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Volume 24 No 6 November/December 1997 Journal Australian Water & Wastewater Association

Editorial Board FR Bishop, Chairman B N Anderson, G Cawston, M R Chapman P Draayers, W J D ulfer, G A H older M Muntisov, P Nadebaum , J D Parker A J Priestley, ] Rissman, EA Swinton

General Editor

CONTENTS

Margaret Metz AWWA Federal Office (see address below)

Features Editor EA (Bob) Swinton 4 Pleasant View Cres, Glen Waverley Vic 3150 Tel/Fax (03) 9560 4752

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From the Federal President .. ... .. .. .. ...... .. .. ... .. .......... ...... .. ...... ................... .. ... 2 From the Executive Director ............................................... ~ ......... .. ............. 4 MY

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OF

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Cuts Threaten Water Safety ......... ...... .. .. ...... .. ............................... ................ 3 P Cullen INDUSTRY

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Profile-Greg Cawston .......... ... ..... ... ........ .. ... ..... ......... .. .......... ....... .. ........ ... .... 7 MMetz WATER When in Rome ... Water Engineering in 97 AD ........ ... ...... .. ...... ........ .. .. ........ 8 R F Goldfinch Ill Aluminium In a Water Supply Part 3: Domestic Tap Waters .... .... .. .. .. .. 11 J Lin, B A Coller [II A Survey of Water Treatment Plants in New South Wales ................... 15 M van Anen , H B Dharmappa WASTEWATER Water Reuse in Spain ........... .. .................................... .. ...... ........ ..... .. .. .. .. .... RT Williams Microbiology Enters the Wastewater Industry in Earnest ....................... T Flapper [I] Heavy Metals Leaching from Biosolids using Sulfur-Oxidising Bacteria .................................................. ... .... ........ .. ..... ... ..... ............... .......... P R Ginige, A Shanableh Gulgong of the No'verflow .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ... .. .. .. .. .. .. . M Laginestra [II On-site Wastewater Treatment: A South Australian Survey ................ NM Kayaalp BUS ,I NESS

19 21

22 27 29

Rewarding Loyalty: The Industry Says Thank You .................................... 33 M Bates [II Water in California: Comparing Private and Public Companies .... .... . 35 B Adamson Water Industry Operator Training .............. .... ....... .......... .. .. .... ......... .......... . 38 J Park ENVIRONMENT Technology Tight On-Site .. ......... ................ ........ ............ .......... .................... 40 C Davis Ill Environmental Regulation of Perth's Groundwater ....... .. .. .... .. ............ 42 B Jenkins DEPARTMENTS From the Bottom of the Well ......... .. ............................................................ .. 4 International Affiliates .. .................. ........... .. ........ ................ ........... ..... .. ...... . 5 New Products ......... .. ....... .. ........ .......... .... .......... .. ... ... .. ..... .. .. ..... .. .. :............... 47 Meetings ........... ....... ..... ........ .. .. .... .... .... ............ ..... .......... ... ... ... ... .. .. .... ........ .. 48 OUR COVER: W etlands are home to our rich diversity of waterfowl. Th ey are sensitive indicators of the quality and quantity of surfa ce and groundwater flo ws. See article on protecting Perth 's gro undwater on p. 42. Photo

courtesy of CSIRO Centre for Groundwater Studies and SA Tourism Commission.


WATER

Pont Du Gard near Nlmes, France, showing the type of masonry construction practised In ancient Rome

Abstract T he year 1997 is the 1900th anniversary of the appointment of Sextu s Julius Fro ntinu s to the position of Wa ter Commissioner to the City of Rome. It seem s appropriate at this time to , pay tribute to this eminent wa ter supply engineer as his con tribu tion to our knowledge of the sub stantial works w hich comprised th e wa ter supply system of the city of Ro m e is outstanding. Following hi s appointme nt, Fro ntinu s investigated th e tec hnical details of R ome's system of aqueducts, tunnels, conduits and service reservoirs that supplied water to the city. H is findings can be fo und in two books, w h ere h e also di scu sses aspects of managem en t that are directly relevant to the supply of wa ter in Australia today, especially in relation to appointing n on-technical people as C hief -Executive O ffi ce rs and th e tre nd towards privatisation of water supply authorities .

Introduction Sextus Julius Frontinu s was born in Sicily in about AD 35 and was educated at the Alexanderan School of M athematics in Alexandria, Egypt. H e was particularly interested in mathematics and physics, especially those of H ero of Alexandria. In 76 AD he was appointed Governor of the Roman colony of Britain , and during the next two years subdued the people of South W ales. As a result of these exploits he was recalled to Rome and prom o ted to the position of General in the Roman army . Frontinu s took part in many other campaigns until in 97 AD he was 8

WATER NOVEMBER/ DECEMBER 1997

appointed C ura tor A quarum or W ater Commissioner of the C ity of R ome. Although Frontinus had a technical educa tion , upon his appointment to the position of Curator A quarum , he was concerned by his lack of knowledge of the city's wa ter supply sys tem and em barked on an extensive study of the system and the legal respon sibilities surro unding it. T hat he did this is our good fo rtune, because we are able to see how the water supply system in 97 AD operated and compare it with our own system today.

Rome's Water Supply System At the time of Fron tin us the R oman Em pire extended fro m Britain to the Persian Gulf and included all the lands surrounding the M editerranean Sea. In 90 AD R ome had a population of 1. 2 million. T his grew to a peak of about 2 m illion during the second centu ry. Following his appointment as W ater Comm issioner, Frontinus prepared a report for the Emperor in w hich he wro te the history of each of the then existing nine aquedu cts, describing by w hom and under w hat conditions each was built. H e recorded the quantity of water each aqueduct delivered to R om e and docume nted details of its length, slope, elevation , source and condition . In about 99 AD he published his reports in De Aquis Urbin R omae-Th e Two Books on the Wa ter Supply to the City ofRome. 1 Following the fall of Rom e in the fifth centu ry the Frontinus manuscript was lost, but in 1897 w hilst on a visit to Italy the inve nto r of the venturi tube, Clemens H erschel (1842-1930), happened to visit the library of the M onastery at Monte Cassino, w here he

di scovered the los t manu script. In addition to being a brilliant engineer, H erschel was also a Latin scholar , so could read the Latin text. H e was also a m ember of the N ew England Water W orks Associatio n (NEWW A) and du ring his visi t to the M onastery H erschel obtained permission to translate and publish the book s w ith explanatory chapters . In 1973 the NEWWA republished H erschel' s tra nslations and commentaries with an introdu ction prepared by two N EWWA members, Russell H Babcock and James J M atera. The opening paragraphs of D e A quis Urbin R om ae are just as relevant to the issues that confro nt today's water supply industry as they were to those responsible fo r the water supply in Rom e. Frontinus recognised the importance of the water supply fo r the health of the R oman community, the security of the city, and the responsibility of the W ater Commissioner as the C hief Executive Offi cer of the water authority. Frontinus's fears were well fo unded becau se w hen the city came under attack by barbarians, one of their first acts was to cut off the city's water supply by toppling over above-ground sections of the aqueducts. The following are quo tations from H erschel's translation of the opening paragraphs of D e A quis Urbin R om ae. ' ... N erva Augustus [the Emperor] .. . has now confe rred ,o n m e the duties of wa ter commissio ner, (or water works superintendent-curator aquarum), duties contributing partly to the convenience, partly to the health, even to the safety of the city, and from olden times exercised by the m ost di stinguish ed citize n s; I


WATER therefore consider it to be the first and most important thing to be do ne, as has always been one of my .fundam ental principles m oth er affairs to learn thoroughly w hat it is that I have undertaken.' 'There is indeed no better foundation for any business; nor can it in any other way be determined w hat is to be done, and w hat omitted ; nor is there for a fa ir-minded m an so debasing a course as to perform the duties of an office entrusted to him according to the instru ctions of assistants, a course, however, w hich must be fo llowed, w henever an inexperience d official takes refu ge in the practical knowledge of his assistants; w hose services though necessary for rendering help sho uld nevertheless be only a sort of hand and tool of the principal in charge ... ' These quotations cause one to reflect on the curre nt practi ce w h ereby commercially oriented people are at times preferred as managers of water supply organisations rather than engmeers .

the aquedu ct was constructed undergro und for security and protec tion against pollution. Its total underground length to the city wall was 17 km. It was then carried on arches for 300 fee t, then went under the city at a depth of 50 feet to end at the Tiber River. Variou s authors give the cross-section of the aqueduct as about 2 .5 feet. wide and 5 feet high. Its elevation was such that only the lowest parts of the south-west of the city could be supplied from it. Nothing of this aquedu ct now remains.

No Flow Control

History of Rome's Water, Sewerage and Drainage For 441 years from the founding of Rome in 754 BC the Romans were content to use water drawn either from the Tiber or from wells or springs . By 312 BC Rome had become a walled city , and with a growing population the need to provide a more adequate water supply had become an urgent matter. In addition to th e need for potable wa ter supply for drinking and domestic purposes , water was required for sewer flu shing, as by this time a system of combined sewers and stormwa ter drains had been developed in the city. Up to that time the sewe rs depended on rainfall for flu shing. Although there was a clear need fo r an improved water supply, the early citizen s of Rome were inten sely opposed to the construction of any large works. They were unprepared to meet the high cost of works, and it was only by great determination that the then Censor, Appius Claudius Crassu s, and C. Plautius were able to undertake construction of the first aq ueduct. According to Frontinus, Appius and Plautius found the spring which they decided to use as the first water source on the es tate of Lucullus on the Praenestine Way 'between the seventh and eighth milestone' from Rome on a cross-road 780 paces to the left, going from Rome . The Roman mile was about 4,850 fee t long, and was subdivided into 1000 'paces.' A pace was a 'do uble step' long. Appiu s nam ed the new aqueduct 'Acqua Appia.' From the intake stru cture on the Lucullus Estate

some distance from the city, and at several places where it crosses valleys, 463 paces on arches, nearer the city, 528 paces on masonry substructure; and on other arches 6,472 paces. In 125 BC Acqua Tepula was constructed on top of one of the lengths of arches of Acqua Marcia. In 33 BC Acqua Julia was built on top of Acqua Tepula. Later two others, Virgo (19 BC) and Absientina (2 BC), were built. T he later stru ctures were built with a core of coarse concrete faced with brick or stone. Because the surface structures of the early aqu educts consisted of good quality stone they were used in later times as a convenient source of building stone and consequently suffered severe damage by quarrying. Little or no thing of these works now remains. T he waters of the Marcia are now used in Rome and the aq ueduct w hich carries the water to the city was built by an English co mpany in 187 0. T hi s aqueduct is called Acqua Pia in honour of Pope Pius IX, or Marcia-pia.

Artist's Impression of an ancient water fountain still fed by Marcia waters

The next aqueduct to be constru cted was completed in 269 BC and named Anio Vetus after the River Anio from w hich it obtained its water. T he intake on the River Anio was located in a mountainous area 43 miles from Rome. Its source was much further from Rome and also much higher. Accordingly, its route included five long loops to reduce eleva tion without increasing grade excessively so that it could enter Rome across a narrow volcanic ridge to the south-east of the city. This aqueduct also served the lower parts of the city. The first two aqueducts were sufficient to supply Rome for the next 129 years w hen the Acqua Marcia was built in 140 BC. This aqueduct tapped a source further away from Rome and at a higher elevation . The water was of better quality and the Acqua Marcia supplied the w hole city by gravity. It was the first of the high- level aqueducts and the last to be built during the republican period of Roman history. It was also the last aqueduct with surface stru ctures built of solid stone blocks. According to Frontinus, Acqua Marcia has a length of 61,710 1/2 paces from the intake to the city; 54,247 1/2 paces of undergro und conduit ; 7, 463 on stru ctures above gro und ; of w hich ,

T h e total length of all eleve n aqueducts was 502 km, of which 422 km were in tunnels and the rest consisting of arches or other surface struc tures. It is estimated that the aqueduct system discharged more th;tn 1 million cubic rn.etres of water into the city every 24 hours. T his high co nsumption results from the fac t that the system was of contin uous flow w ith no means of reducing flow during periods of low demand and also because of the large number of fo untains and public baths to be supplied. Inverted siphons were widely used once the aqueducts entered the city to pass under obstructions. Often these were made of lead in sizes from 1 1/4 inches to 24 inches. Pipe was made of bored stone blocks or of clay cas t in cement. Waters were distributed in the city by a system of tanks and o utlets. T he city reservoir led to three cisterns. One provided wa ter to public baths, the second to private dwellings, with a third of the water and overflow fro m the other two cisterns discharging to a third or central cistern. Water was thus provided to pools and fountains and ultimately for flu shing sewers. Th e wa ter supply fl owed continuously and the many magnificent fo untains in Rome are not only decorative, but an integral part of the water system.

,

Water Quality According to H erschel, the waters of Rome wo uld be co n sidered hard , ranging from 110 to 480 ppm CaCOy The interiors of the aquedu cts are badly encrusted with hardness minerals. The WATER NOVEMBER/ DECEMBER 1997

9


WATER water was tested for quality by the way it cooked vegetables; the presence or absence of sediment in a vessel on standing, or on the sides and bottom on boiling down. Water was examined for taste and odour. If the local inhabitants who used the source were in good health, the water was considered safe. These are the classic beginnings of the modern sanitary survey as a means of evaluating a water supply.

Water Ordinances Frontinus established regulations and penalties for the violation of water department ordinances. His regulation to maintain water free of pollution was: ' No one shall with malice pollute the waters where they issu e publicly. Should anyone pollute them, his fine shall be ten thousand ses tertii ' (equivalent to about $800).' The quantity of water that a person was allowed to draw was controlled by the general ordinance: 'that no one shall draw water without a writing from Caesar, that is , no one shall draw water from a public supply without a licence, and no one shall draw more than has been granted.' Frontinus reported on regulations concerning repair and maintenance of the aqueducts which required that a

clear unoccupied space of 4.6 m shall be maintained ori each side of springs, arches and walls of an aqueduct. This also reflects present day practice.

Conclusion Herschel referred to Froncinus's statem ent ab out the importance of proper maintenance of water works: ' It has seemed to me not superfluous to examine consecutively the lengths of channel of each aqueduct in its several parts and in detail-because the maintenance of the works is the most important part of the duties of this office, wherefore it is necessary that whoever is placed in charge of them should know w hich of them are in need of having money spent on them. But my zeal was not satisfied by a mere personal examination in detail; I also had plans made of the aqueducts, from w hich it may be seen where there are valleys, and how wide they are, and where rivers have been crossed; also w here the conduits laid on hillsides need an extended and continued care for their protection and maintenance. In this way we reap the advantage of having, as it were, the works referred to directly before us, and of being able to study them as though we stood by their side.'

SPECIALISING IN ENVIRONMENTAL SERVICES

References

..,. Solid Waste Management

1. This article has been prepared from De Aquis Urbin Romae--The Two Books on the Water Supply to the City of Rome, by Sextus Julius FrontinusWater Commissioner of the Ciry of Rome AD 97, translated into English, with explanatory chapters by Clemens Herschel, H ydraulic Engineer, and an introduction by Russell H Babcock and James J Matera, published by the New England Water Works Association, Boston, Mass ., USA, 1973.

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10

This refers to the absolute importance of the maintenance function in the administration of water supply systems and the necessity of developing and maintaining full and complete plans of all components of water supply works. It seems to reflect concerns being expressed regarding attitudes which appear to be developing in those water organisations in which in recent times public sector administration has bee n replaced by private company organisations. It ha~ been reported that as a result of privatisation, maintenance of records and other operation and maintenance activities have been reduced in certain organisations to a level which may have serious effects on the adequacy and quality of water supplied to consumers, and hence become a threat to the health of the community. This is a situation which Frontinus would have found unacceptable. Frontinus was acutely aware of the importance of adequate and wholesome water supply for the well-being of the citizens of Rome and that the government is responsible for the health of citizens. Whilst there is a role for the private sector in the provision of water supply, the responsibility for public health must remain with the public sector and not be abrogated by governments. For this reasbn the public sector should continue to provide a controlling and directing involvement in the provision of water supply and sanitation services.

WATER NOVEMBER/DECEMBER 1997

Reginald (Reg) Goldfinch is an Honorary Life Member of the Australian Water and Wastewater Association and was Federal Secretary/ Treasurer from 1971-77. He retired from the position of Assistant Secretary (Environmental and Coastal Engineering) of Australian Construction Services in 1990. Since his retirement he has been involved in various 'water supply proj ec ts in Indonesia, the People's R epublic of China, Somalia and Nigeria. H e has an interest in the archaeological aspects of water supply and sanitation. His address is PO Box 193 Jamison ACT 2614.


m

WATER

IN A WATER SUPPLY PART 3: DOMESTIC TAP WATERS J Lin, B A Coller Abstract A further study of aluminium and iron levels in drinking water supplied from the Sugarloaf Reservoir, M elbourne, is summarised. Parts 1 and 2 of Aluminium in a Water Supply reported the species in the Su~arloaf Reservoir and throughout the Wmneke Water Treatment Plant (Coller and Lin, M ay/June issue of Water, 1997). T he treatment process , which use s aluminium sulfate as coagulant, reduced particulate aluminium from 190 to 5 µg/L and colloidal aluminium from 77 µ/L to 10 µg/L. Soluble species, which totalled 8 µg/L in the raw water, were only marginally increased to 10 µg/L. Part 3 discusses the aluminium levels and species in domestic tap water supplied from this treatment plant and compares them with two other water supplies. Between the treatment plant and the tap there was an increase in average levels of particulate aluminium from 5 to 45 µg/L. The levels of colloidal aluminium remained virtually unaltered at 10 µg/L, but the levels of soluble aluminium, after fluorid ation, and transport through both cement-lined and iron pipes increased from 9 µg/L to ca. 18 µg/L. Po ssible reasons for the increase are discussed. All these values are well below the NHMRC 1987 Guideline of 100 µg/L.

Introduction The Sugarloaf R eservoir is located north-east and 32 kilometres from the centre of Melbourne, Victoria. It stores and sediments water pumped from the Y arra River and the Maroondah Aqueduct, and delivers it during peak demand seasons to the Winneke Water Treatment Plant, where it undergoes conventional treatment using

aluminium sulfate. T he sequence of treatment is coagulation , flocculation, sedimentation , sand filtration, pH correction, chlorination and clearwater storage, followed by fluoridation using sodium silicofluoride about 10 kms downstream. The water then flows into the north-eastern reticulation system , which in other periods of the year is supplied from the upper Yarra reservoir, w hich stores water from M elbourne's pristine catchments, where treatment is simply chlorination and fluoridation. For comparison, a few samples were also taken of water supplied from the small Tynong water treatment plant in Gippsland, which treated water from the Tarago reservoir using aluminium sulfate but where fluoridation (using sodium fluoride) was carried out prior to coagulation and filtration , and also of water supplied from the Cardinia reservoir, which stores water from pristine catchments for an average of four years , so that treatment is only chlorination and fluoridation (using hydrofluorosilicic acid).

Sampling and Analysis Aluminium and other water quality parameters were measured in treated water samples taken from the clearwater storage at Winneke on five separate occasions from September 1993 ·to August 1994. Two samples were taken from upstream and 10 km downstream of the fluoridation plant. Tap water samples from six properties supplied by Winneke were taken from August to December 1993. Pipe distances varied from approximately 3 to 10 km from the fluoridation plant. Tynong samples we re taken from two properties 25 km from the treatment plant and Cardinia samples were taken at Monash University also 25 km from the reservmr.

Sample treatment and analysis methods are detailed in Parts 1 and 2 of Aluminium in a Water Supply (Coller and Lin 1997). To summarise, aluminium speciation was defined by the following procedures: • digestion by 5% HNO 3 to determine total aluminium, then sequentially: • gravity filtration' on 0.45 µ m Millipore filters to determine particulate aluminium • tangential flow filtration (TFF) on 0.003 µm Minitan plates to determine colloidal aluminium • extraction with 8-hydroxyquinoline to determine soluble species, which were then separated by a cation exchange column into inorganic and organic complexes. Aluminium analysis was performed by graphite furnace AAS. It is generally believed that the soluble species are those most likely to be absorbed in the digestive tract of humans , but research is in progress to assess to w hat extent the colloidal species can be absorbed.

Results and Discussion Common Parameters Table 1 summarises the common parameters for the treated water leaving the Winneke Water Treatment Plant and the average values for samples taken from suburban taps. Except for the extra fluoride they are very similar, but two single high pH values may have been caused by new concrete m'<lins. Alumlnlum Species Table 2 and Figure 1 compare the average aluminium levels and species in the raw, treated and tap water. It is clear that total aluminium levels in the tap water were much higher than in the WATER NOVEMBER/ DECEMBER 1997

11


WATER treated water. Particulate aluminium increased from 5 to 45 µ g/L (range 26-55). However, colloidal aluminium was virtually unch ange d at ca.1 0 µ g/L(range 6-17) bu t that portion which passed TFF (smaller than 0.003 µm ), i.e. the monomeric organic alu minium and monomeric inorganic aluminium, doubled from 9 µ g/L to 18 µg/L (range 16-21). Although the total aluminium levels found in all these domestic tap water samples were consistently 2 to 3 times the levels fo und in the treated water that entered the water mains leaving Winneke, they were all well within the World Health Orga nization (WHO) (1993) achieva ble value of 0.1 mg/L (100 µg/L). A similar result was found by Pitchai et al. (1992) in Madras, South India , w here wa ter in the distribution system had increase d in aluminium levels by corn.parison with the natural water resources. Table 3 and Figure 2 summarise the changes in the computed concentrations of the monomeri c inorganic species, based on ionic equilibrium constants. Al(OH) 3 , Al(OH) 4- and Al(OH)/ were all higher in the domestic tap water than in the water leaving Winneke, and the presence of fluorid e registers as AlF 3 and AlF 2- species. Iron levels in the treate d water averaged 7 µg/L but rose to an average of 26 µg/L in tap waters. M anganese levels were low (<6 µg/L) in all samples.

Possible Reasons Seve ral possible ca uses m ay be advanced to explain the finding that aluminium levels in the domestic tap water were two to three times higher than those in the final water leaving the Winneke Water Treatment Plant.

The Fluoridation Process To test the possibility that aluminium could have b een added as an impurity in materials used for fluorida. tion, aluminium levels were m easured before and after fluoridation . It was found that fluoridation led to only a small increase in levels of all aluminium species, including monomeric aluminium and monomeric inorganic aluminium.

For example, the total aluminium level was 40 µg/L before fluoridation and 45 µ g/L after fluoridation, i. e. it had increased by only about 10%. Computed aluminium fluoride species in the tap water account for less than 3 µg/L.

Leaching and Erosion of Concrete Linings of Water Mains The average total aluminium level in the final water leaving Winneke was 26 g/L. In the water entering the fluoridation plant after travelling 10 km downstream of Winneke the level was 40 µ g/L-about one third more aluminium than in the final water. B etween the water leaving the fl uoridation plant (45 µ g/L) and the domestic tap water the total aluminium approximately doubled (average of74 µ g/L, and highest value of 93 µg/L). It was also fo und that aluminium levels increased with distance from the plant. It can therefore be suggested that the mains system or distribution system was the source of aluminium species . Cem ent-lined m am s migh t be leached or eroded to release impurities including both particulate and soluble aluminium compounds. Corrosion of Metal Water Pipes Corrosion might be caused by physical processes such as water motion , by chemical processes due to the presence of oxygen and carbon dioxide or other species in treated water, by electrochemical processes such as those due to the presence of dissimilar metals, or even by bacterial action (Twort et al. 1985 ). All these types of co rrosion could release m etals into treated water. However, the major m etal released by corrosion, Fe , shows an increase of only 20 µ g/L. Since the proportion of aluminium compounds in steel is extrem ely small, this does not seem to be a plausible source of the relatively large increase in soluble aluminium. Leaching and Erosion from Sediments and Films Accumulated in Mains and Pipes Leaching and erosion of sediments and film s accumulated on the wall of pipes and mains is another possible source of increase in aluminium levels

Table 1 Common pa rameters of Winneke water

pH NTU E.C uS/ cm mg/L alkalin ity S0 4 Cl N03 F

12

Filtered

Ta p

7.1 0.1 90

6.7 - 7.0 0.1 97

8 .7 8.4 14.7 0.22 0.035

10.4 8.4 15.6 0.22 0.92

WATER NOVEMBER/ DECEMBER 1997

50

40

particulate colloidal

monomeric

30 ...J

0,

"20 10

Tap

Figure 1 Ave rage alumin ium levels in t he treated water leaving Winneke Water Treatme nt Plant · an " in the domestic tap water supplied by Winneke 12 10 8

'§, :,

41-i

AtHr Al OH Al OH 2 + AIF2(+) AIF3

6

4 2 0 Treated

Tap

Figure 2 Computed levels of monomeric inorgan ic alum in ium species in the treated water leaving Winneke Water Treatment Plant and in the domestic tap water suppl ied by Win neke

during delivery. Erosion of sediment would be consistenf with the considerable increase in particulate aluminium in domestic tap water (Figure 1). Figure 3 is a photograp h of old steel pipes, showing a dense inside layer, caused by the sedimentation of parti culate m aterial in the tap wa ter. Such sedimentation on the wall of pipes could be leached and eroded into the tap water when the water fl ows rapidly under high pressure. X-ray fluorescence (XRF) spec tra from two particles of sediment collected from the walls of the pipes indicate that the sediment consisted largely of aluminium, silicon and iron, which is as expected if clay and rust were the major components. These materials might have entered the wa ter in the pipes as particulate , colloidal or eve n as dissolved materials during its delivery from the unfiltered sources.

Table 2 Aluminium species in water sam ples as Al µg/L Raw water

Winn eke fi ltered

Km downstrea m

Total Comprising Particulate > 0.45 um Colloida l >0.003 um Sol: inorga nic Sol: orga nic

Fluori dation

Domestic supplies Winneke Tynong Cardin ia

10

20

25

25

200

25

40>45

74

140

140

114

5

23

45

96

72

77

10

9

11

26

55

4 4

8 1

13 1

17 1

22 1

23 <1


WATER Aluminium Levels in Other Domestic Tap Waters A total of six domestic tap water sa'mples supplied from T ynong and Cardinia reservoirs from August 1993 to January 1994 w ere also analysed, and averages are reported in Table 3. The total aluminium levels in three samples of the domestic tap w ater supplied by Tynong were 184, 138, 114 µg/L, i.e. about twice that in the domestic ta p waters supplied by Winneke. Levels of colloidal species were 2-3 times Winneke, but soluble species were only slightly higher. It might be suggested that fluo ridation prior to coagulation and filtration 1eads to more inorganic aluminium . species remaining in solu tion through the treatment stages . Aluminium levels in three samples of domestic tap wa ter supplied by Cardinia in Spring 1993 were 107, 125, 189 µg/L. Th e long-term average level leaving the reservoir is 60 µg/L (pers. comm. M elbourne Water). Colloidal species w ere, on one analysis only, over double those determined for Winneke tap wa ter, but soluble species were about the same. The average total aluminium levels in the domestic tap waters supplied by Tynong (145 g/L) and by Cardinia (140 µg/L) were all within the WHO (1993) guideline value of0 .2 mg/L (200 µg/L).

Conclusion: Part 3 The aluminium levels in domestic tap waters supplied by Winneke were grea ter than in the final water leaving Winneke by as much as tv.ro to three times, but the average value, 7 4 µg/L, was still lower than the achievable value of 0.1 mg/L (100 µg/L) and considerably lower than the guideline value of 0.2 mg/L (200 µg/L) for drinking water recommended by WHO (1993) . The increase in the total aluminium levels during delivery from Winneke to the domestic tap water might be due to leaching and erosion of cem ent linings in water main s, the leaching and erosion of the sediments and films of clay and suspended material accumulated on the walls of pipes and less likely to corrosion of m etal pipes. A slight increase in m onomeric Table 3 Computed soluble species

Filtered

µg/ L as Al Fluoridated

Tap

Al(OH)3

6

9

11

Al(OH)4 -

1.3

2

3

Al(OH)2 +

1

1.6

1

AIF/

0

1

1

AIF 3

0

1

2

Figure 3 Cross-sections of pipes used for 35 years. Note the denser dark-orange layer on the pipe walls

inorganic aluminium in the domestic type of raw water, and realising the tap water might have been caused by effect of other ions and organics on the fluoridation. Fluoride forms very stable solubility of aluminium, similar detailed aquo-aluminium-fluoride ions , which analysi s of other treatment plants c uld enhance the solubilisation of throughout Australia seems justified. the colloidal aluminium-organo complexes. However, even though the level Acknowledgments of fluorid e in the water was ca. 900 This research was carried out by µg/L, the computed level of aluminium Jianping Lin as part of his PhD progra m flu oride species was only ca. 3 µg/L, in th e D epartm ent of C hemi stry, which is not enough to account for the Monash University, C layton under the extra solubles. Some research on this supervision of Dr Bruce Coller. m atter would seem to be justified. Further details and a dissertation on aluminium analyses at these low levels Overall Conclusion: Parts 1, 2, 3 and m ethods of filtration to assign The raw water taken from the speciation are available inJianping Lin 's Sugarloaf reservoir, even after long- thesis, Aluminium Speciation in a term sedimentation , contains high W ater Supply, 1995. The thesis also levels of particulate Al, mainly as clay contains the results of analyses on particles, but soluble aluminium was at typical stream , river and lake waters. very Iow levels. As expected , the particThe proj ect was suggested by the ulate aluminium was reduced to National H ealth and M edical R esearch minimal levels by coagulation and filtra- Council. Thanks to M elbourne W ater tion . However, although the coagulant for permission to carry out the study, to used was soluble aluminium sulfate, it Noel Miles at Winneke W ater had minimal effect on the levels of Treatment Plant and to Alex Harrison colloidal and soluble aluminium species, and Robyn R eid at M elbourne Water which remained at ca. 10 µg/L each. Laboratory for assistance with some of Passage through 10 km of cement- the analyses for anions. lined mains increased particulates from 5 to 19 µg/L and total aluminium from References 29 to 40 µg/L. Coller BA and Lin J 1997 (May/Ju ne). Aluminium in a Water Supply. Water. The fluoridation process, using 24(1):18. sodium silico-fluoride, increased total Pitchai R , Subramanian R , Selvapathy P and aluminium by only ca. 10%. Elangovan R, 1992. Aluminiu m Content Subsequent passage through som e of D rinking Water in Madras. Wa ter kilometres of cement-lined mains and Supply. 10(4): 83 . old iron reticulation pipes resulted in T wort AC , Law FM and C rowley FW. 1985 . further increases in total aluminium , W ater Supply, 3rd Ed. Edward Arnold. which was almost all particulate. The Scotland. level of colloidal aluminium species was WHO . 1993 . Guidelines fo r Drinking- water Quality. Vol. 1, R ecomme ndatio n . unchanged at ca. 10 µg/L, but the W orld Health Organization. Geneva. soluble aluminium species had doubled to some 18 µg/L. The results of this research m ay cast Authors Dr Jlanplng Lin specialises in trace doubt on the rationale fo r substituting iron coagulants for aluminium coagu- element analysis. His address is C/lants since the treatment plant using WSL Consultants Pty Ltd, 2-8 H arvey alum had minimal effect on the more Street, Richmond, Victoria 3021. readily assimilated colloidal and soluble Dr Bruce A Coller is Senior Lec turer species, but the subsequ ent pipework in the D epartment of Chemi stry, had a significant effec t, albeit at levels Monash University, Clayton , Victoria only some 10% of WHO guidelines. 31 68 . H e specialises in trace elem ents This research was performed on one analysis. WATER NOVEMBER/ DECEMBER 1997

13


Abstract

Sources of Water

In New South Wales there are about 120 water treatment plants responsible for the supply of safe and palatable drinking water. As the information coq_cerning these plants is limited and scattered, this survey is an attempt to provide an informative database which should prove valuable in the areas of design, upgrading and future planning of water treatment plants. The article discusses water sources, the capacity of treatment plants, the quality of raw and treated water, treatment plant configurations and costs , and sludge management options.

D am storage appears to be the major source of water in New South Wales (see Figure 1). If the combined capacity of all the plants in N ew South W ales is considered, dam storages account for 86% of the raw wa ter supplied . However, when the Sydney metropolitan area plants are excluded, this figure is reduced to 51 % . While the dams contribute the greatest volume, rivers are the most common source of drinking water in New South W ales (see Figure 2) . This result is vastly different from other states such as South Australia an d the Northern T erritory w hich , outside the metropolitan areas, rely mostly on groundwater sources. In the Northern T erritory, for example, 4 7 of the 50 largest communities rely on groundwater for their water supplies (D epartment of Resources and Energy, 1982).

Introduction This survey is a continuation of the work carried out by Fraser (1994). The main obj ectives of the survey were to examine raw water qualities, provide cost analyses of various plant configurations , investigate future design alternatives and identify sludge management options . Of the estimated 120 plants surveyed, 57 including those surveyed by Fraser in 1994 returned the survey forms , with varying levels of detail. However, in some of the data analyses, information from most of the remaining plants is also included. This information was collected mainly from leaflets and brochures published by the N ew South Wales Department of Land and W ater Conservation (DLWC), which manages around 97% of the plants in New South Wales. For confidentiality reasons , the findings are presented in such a manner that individual works and water authorities are not singled out. It should be noted that most of the treatment plants surveyed in this study were constructed between 1980 and 1995.

demand due to population growth. However, further studies are required in order to assess how effectively these excess capacities are being used.

Surface Water Quallty Raw surface water quality generally appears to be of a high level (see Figures 5 and 6) . However, compared to the drinking water guidelines set by the National H ealth and Medical Research Council/Agricultural and Resource M anagem ent Council (NHMRC/ ARMC) (1996), most of the raw water sources require treatment before supply to the community.

Groundwater Quality As most of the population centres in N ew South Wales have access to surface water supplies , only about nine water works use groundwater as their source

Capacity of Treatment Plants The water treatment plants surveyed vary in size from under 1 ML/d to about 250 ML/d. The distribution of the number of water treatment plants with respect to total capacity ranges is given in Figure 3, w hi ch shows that the largest number of plants surveyed lies in the range of 1 to 49 ML/d of capacity, with about 20 out of57 plants surveyed lying in the capacity range of 1 to 9.9 ML/d. This is to be expected , as most of the plants are designed to supply water to the small communities. In order to compare the actual daily production of water w ith the total installed capacity of the plant, percentage use was calculated (see Figure 4) . In most cases the treatment plants opera te at abo ut 20-40% of their total design capacity. The excess capacity may be allocated to meet peak demands in a particular season and to meet future

Iâ&#x20AC;˘ Dam D River (Direct) a Other I Figure 1 Water sources by volume

"'

ii .. l,o

â&#x20AC;˘ L. i 10

Figure 2 Number of water works using different water sources WATER NOVEMBER/DECEMBER 1997

15


WATER colour of less than or equal to 5 TCU, w hich is well below the guideline value of 15 TCU se t by the NHMRC/ ARMC (1996) . The treated water turbidity generally varied between 0.2 and 0.6 NTU. Most plants aimed to achieve a treated water turbidity of 0.5 NTU. Bacteriological quality was not assessed in this study.

(see Figure 2). D espite the few sets of data recorded, trends regarding groundwater quality are evident. These consist of relatively low pH valu es ranging from 6.3-6.9, low colour (5-40 TCU) and turbidity values (12-35 NTU) , yet relatively high valu es of hardness (19-145 mg/Las CaCO 3) and iron (Fe) levels (0.36-6.4 mg/L).

was then analysed against the plant's capacity to id entify the relationship between plant capacity and operating cost. The results are presented in Figure 10, which indicates a trend w here an increase in plant capacity is accompanied by a substantial decrease in the unit cost of production. Especially for plants of greater capacity than 100 ML/d the unit cost of production is about 1/6th of that of 1 ML/d . A regression analysis of the data presented in Figure 10 resulted in the following relationship: oc = 331 Q-04346 R 2 = 0.72 .................................. . (2)

Treated Water Quality Treatment Plant Costs

The treated water quality is compared with the NHMRC/ARMC (1996) guidelines for drinking water. The water quality parameters used for comparison are turbidity, colour, pH , hardness, manganese and iron levels. Treated water colour and turbidity are . plotted in Figures 7 and 8. The results show that there is a general compliance by most of the plants. Only four plants reported values exceeding the guideline levels as follows: • two plants reported turbidity of 1.2 and 7 NTU against the guideline value of1 NTU • one plant reported an iron level of 0.76 mg/L against the guideline value of 0.3 mg/L • one plant reported a manganese level of0 .11 m g/L against the guideline value of0.1 mg/L. Figure 7 shows that the treated water colour generally lies below or equal to 5 TCU . This indicates that most of the plants aim to achi eve a treated water

Capital Costs The analysis of capital costs of the wa ter treatm ent plants yielded the expected results. The regression analysis of the data presented in Figure 9 yields the following relationship:

where OC = operating cos t, $/ML The costs of specific treatment plant configurations were very hard to assess due to the limited amount of information provided. However, some information was gathered co ncerning alternative plant configurations in N ew South Wales, as well as other states in Australia. These are summarised below. Contact filtration was found to have both operational and capital cos ts similar to those of direct filtration. Dissolved air flotation (DAF) systems have larger power requirem ents compared to other system s available. They therefore have large energy bills, resulting in higher operatiqg costs . One treatment plant operating a DAF system along with a dual m edia filtration has a capacity of 10 ML/d . The yearly power

cc = 0.6443Q0.8012 R 2 = 0.81.. ...... .... ........................ (1) w here CC = capital cost, $M Q = design flow rate , ML/d R 2 = correlation coefficient The expo nent in equation (1) indicates the economies of scale available in the water treatment plants. As the exponent is significantly less than 1.0, there is a considerable amount of economy of scale available for water treatment plants. Operational Costs The operating cost data from the plants was supplied in terms of cost per unit of production ($/ML). This data 80 ~

70 ~

r::

60

0

"'!j

50

~

c. 40 J!::-

{!

30

...<.•.

i ~f 20 p

"' >200

100 - 200

19.9

10-

50 · 99

49

10

<1

0 100

0

Total capacity intervals, MUd

0

100

••

100

I-

~ 8

.

2

I-

• •• 10

••

~

z

.

INHMRC/ARMC( l996) guideline

-

-

10

-

;i,

-

I

'6

:e

::,

I-

Figure 5 Tru e colour of raw surface water

WATER NOVEMBER/ DECEMBER 1997

.. •

.

.

• .

•• •

..-.- • .

.

••• • • •

NHMRC/ARMC(l 996)

0.1

Water works

16

.

.

300

400

500

Figure 4 Average da ily production in terms of tota l capac ity of the plant

1000

:)

200

Total capacity of plant, M Ud

Figure 3 Distribution of water treatment plants in terms of t heir capacities (new Sydney Water treatment plants are not included)

-·•

8,

• Water works

Figure 6 Turbidity of raw surface water

--

. •


WATER bill for this plant is about $260,000. With the plant producing around 1440 ML/year, this works out to be $180/ML just for the power alone. For a lagoon sedimentation plant of similar capacity, the overall operating cost was found to be less than $180/ML. Therefore, the operating cost of a DAF system generally appears to be higher than other treatment sys tems such as lagoon sedimentation . The SIROFLOC process has been tried in two full-scale plants , using the 'M ark 1' system. The first 35 ML/d plant (1981) in Western Australia has since been decommissioned, as the raw water can now be treated successfully by conventional coagulation. The second 20 ML/d plant in Tasmania (1983) is still operating successfully on a highly coloured raw water. No information was available on any plants using the improved 'Mark 2' system (Kolarik and Priestly, 1995) . The microfiltration plant surveyed reported that it is too early in the system operation for an accurate estimate of unit operating cost.

Treatment Plant Configurations Until recently conventional water trea tment plants were the most commonly found plants in New South Wales. This is now changing at a fairly rapid rate. Almost all the new plants built over the past ten years have been

Dewatering method

As there are several treatment and disposal options available for managing water treatment plant residuals, the survey also collec ted information concerning the sludge management practices being undertaken at various plants. The three aspects investigated under sludge management practice were sludge dewatering, supernatant disposal and sludge disposal.

No. reported

31

Sludge lagoons Drying beds Centrifuge Conditioning/thickening

4

1 4

either lagoon sedimentation or direct filtration. Also , some of the advanced trea tment technologies such as microfiltration and dissolved air flotation systems have prominently gained a place or two . The performance and economic information from these plants will be useful in assessing these technologies for future use. Lagoon sedimentation plants were first constructed in 1989 by the then Public Works Department (PWD) . There are now 18 plants operating in New South Wales , with a high possibility of more to follow. These plants are being located in small country town areas and are soon very likely to outnumber conventional treatm ent plants operating in similar areas . For areas with larger populations, direct filtration plants have been the primary choice of the Department of Land and Water Conservation (DLWC) for some years now. Sydney Water has also opted for direct filtration instead of conventional plants for its four new treatment plants being constructed at vanou s locations m the Sydney metropolitan area.

I

INHMRC/ARMC(1996) guideline (15 TCU)

12

Sludge Management Options

Table 1 Sludge dewaterin g methods

Sludge Dewatering Plants in both the USA and UK rely on a number of methods to provide the dewatering of sludges. In USA plants tend to co n centrate sludges u sing mechanical m eans of dewatering such as centrifuges, vacuum filters, and filter presses (Cornwell , 1987) . In the UK, about 38% of the plants producing alum sludges are dewatered by using mechanical devices. The remainder undergo a simple settlement treatment in sludge lagoo n s and d rying beds (Warden, 1980). In the current survey, 40 treatment plants gave some information on the dewatering m ethods they adopted. As shown in Table 1, the m ost common method of dewa tering is sludge lagoons. Information supplied by the DLWC also supported this finding-74 of the 106 water treatment plants under its control have sludge lagoons. Four plants stated that no dewatering method was u sed due to their specific disposal

10

10 ::,

.....: (.)

8

i!

6

...2

4

8.

,.

. INHMRC/ARMC(l996)

2

.

•••

..

:

..

:

-

.. ..

..............

:

.

0 .1

..

...

- .

.

-• •••

0

:

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Water works Water works

Figure 7 Treated wate r co lour

Figure 8 Treated water turb idity

.

400

'

350 ...J

~

t

.

300 250

u 200

"' C

~

150

!

100

Capacity, MUd

Figure 9 capac it ies

.."""., .. '

2

R

0.1

=0.7208

• •

.

50 0.1 + - - - - - - + - - - - - - + - - - - - - + - - - - - - - - - < 10 100 0.1 1000

V =33 1x"04346

~

10

100

1000

Capac ity, ML/d

Capita l cost of wate r treatm ent plants for different

Figure 10 Water treatment pla nt operating costs WATER NOVEMBER/DECEMBER 1997

17


WATER methods. Only one plant (capacity 2 ML/d) reported the use of a mechanical device (i. e., the centrifuge) for dewatering. The centrifuge is used in conjunction with sludge lagoons. Sludge is first conditioned with a polyelectrolyte. Of the four plants that reported the use of either sludge conditioning and/or thickening, three used a gravity thickener where a conditioning agent was added. T he remaining plant used only a conditioning agent for the treatment.

Distances were given for both on-site disposal sites as· well as off-site landfill locations. Considering both on-site and off-site disposal options , the average haulage distance was worked out as 6.5 km. Subsequently, any site wi th a haulage distance of 0.5 km or less was classified as an on- site disposal method and the value was dropped from the calc ulation. T he average h aulage distance was then calculated for off-site disposal, which averaged 8.9 km.

Supernatant Disposal T h e reported u se or disposal of supernatant amongst the plants varied quite considerably. The reported uses were as follows: • 13 plants recycled the supernatant back to the start of the treatment process • 11 plants returned the supernatant back to the wa ter source. If the water source is a river, a discharge licence from the Environment Protection Authori ty (EPA) is required • 6 plants discharged into creeks or rivers that were not the source of the water supply. An EPA licence is required for these discharges • 3 plants left the superna tant in the pond co evaporate • 3 plants u sed the superna tant for irrigation • 2 plants discharged the supernatant into the stormwa ter drainage system • 2 plants discharged the supernatant into the sewer system.

Conclusions

Sludge Disposal A total of 41 plants gave information regarding the disposal of the final solid wastes. The various disposal methods reported are as follows: • 14 plants disposed of the sludge at a dedicated landfill • 11 disposed of the dry sludge at a garbage tip • 8 plants had on-site disposal • 3 plants used sludges for land application purposes • 3 plants di scharged the sludge ·directly into the sewer • 2 plants discharged filter backwash direc tly into stormwa ter drainage system s. Some plants did not quote their slu dge disposal method because they have not yet had to empty their sludge pond and they were still examining potential disposal methods. It appears from the above that disposal of sludge to landfill is the most common method being practised in New South Wales. Twenty-five plants have sludges landfilled , either at a designated landfill or at a municipal tip site. Mo st on-site disposal methods also incorporate the use of a landfill. Twenty-eight plants gave approximate haulage distances for transporting their sludge to the final disposal site. 18

WATER NOVEMBER/ DECEMBER 1997

Survey form s were sent out to 120 plants. Fifty-seven plants returned the forms . The results from the su rvey show that surface water is the main source of wa ter in New South Wales. T rea tment of raw water is achieved using various sys tem co nfiguration s. The treated effluent quality from all the plants generally meets the NHMRC/ AMRC (1996) guidelines except for a very few cases. The m ajority of treatm ent plan t operators were satisfi ed with their current system. However, there were four plants chat reported an absence of disinfec tion and requested an immediate upgrading of their plants to include a disinfec tion process. A few plants also commented that they were understaffed due to cost cutting measures. Direct filtration and lagoon sedimentation plants appeared to be the most popular system configurations currently being u sed by Sydney Water and DLWC respectively. Lagoon sedimentation plants are being used for plants with capacities of ::;10 ML/d. On the other hand, direct filtration system s are being adopted for plants with capacities of>l0 ML/d. One significant finding of the survey is that the unit cost of production of a treatment plant reduces drastically with the increase in capacity. The unit cost of production for a 100 ML/d plant was found to be about one sixteenth of that of 1 ML/d. There is therefore a significant advantage in building large plants . This indicates that it may be economical to constru ct a large treatment plant at one place and di stribute the treated water through large transmission mains. However, a detailed economic analysis has to be carried out before selecting the final option. With the D epartment of Land and Water Conservation con structing over 50 sludge lagoons since 1980, the general trend amongst plants is to use sludge lagoons as a dewatering method . The general trend for dealing w ith supernatant is to recycle it back to the start of the treatment process. Some plants which are still disposing of the supernatant listed this as both a long-or

short-term problem w hich the plant needs to deal with.

Acknowledgements The authors wish to thank all the water treatment plant operators and managers w ho took time to complete and return the survey forms. Their efforts are much appreciated. Sincere thanks are also extended to Donald Fraser for carrying out the initial survey of water treatment plants and for the help he provided ,to the first author during his thesis work. Valuable contributions made by M argaret Metz , General Editor, Water, towards editing of this paper are greatly appreciated.

References Co rn well DA, Bishop M and Go uld R (1987). Water Trea tment Plant Waste Ma nag ment, AWW A R esea rch Foundation, Denver, Cola rado. D epartment of R esources and Energy (1982) . Water 2000: A Perspec tive on Australia's Water Resources, Australian Government Publishing Service, Canberra. Frase r DR (1994) . A Survey of Wa ter Treatment Plants in NSW. BE Thesis, University of Wollongong, Wollongong. Kolarik LO and Priestley AJ (1995) . M odern Techniques in Water and Wastewater Treatment. CSIRO , Melbourn e. N HMRC/ARMC (1996) . Australian Drinking Wa ter Guideli.nes. National H ealth and Medical R esearch Co uncil and Agricultural and Resource Management Council of Australia and New Zealand, Ca nberra. Warden JH and Craft DG (1980). Wate1works Sludge : Production and Disposal in the UK, WRC Environmental Protection, London.

Authors M van Anen recently obtained a BE (Environmental Engineering) degree from the University ofWollongong. H e is currently undertaking work experience at the D epartment of Land and Water Conservation and is keen to continue his work in the area of water and wastewater treatment. H e can be contacted on tel. (02) 4226 1053, fax (02) 4221 3238. H B (Dharma) Dharmappa is a lecturer in the D epartment of C ivil , Mining and Environmental Engineering at the University of Wollongong, Northfields Avenue, Wollongong NSW 2522. H e is currently carrying out research in the areas of design and opera tion of water and was tewater treatment processes. His other current research area is on-site waste disposal sys tem s. H e is lea ding a gro up of researchers w ho are developing appropriate waste disposal technology for rural Aboriginal communities. H e can be contacted at the above address or tel. (02) 4221 4492 , fax (02) 4221 3238, email dharma@ uow .edu.au


WASTEWATER In April 1997 I was fo rtunate to attend an international conference in Spain on the Beneficial R euse of W ater and Biosolids. The conference was held in Marbella , M alaga, Spain from 6- 9 April 1997. The C onfe ren ce w as run by the Water Environment Federation (WEF) in conjunction with ADE CAGUA , the Spanish Professional So ciety for Environmental Scientists and Engineers. T h e E uropean Water Pollution C ontrol Association (EWPC A) also supported the conference . The confe ren ce was attended by approximately 300 professionals of · w hom more than 80% w ere from Spain , with most of the remainder from European countries. Australia was well represented for its population with four attendees, while the USA had 15 representatives, m ost of w hom are key players in the wa ter and biosolids reuse field . Arriving at the M alaga airport brought home the difficulties of being in a non- English sp eaking coun try . The attendants at the Info rmation desk spoke broken English and info rmed m e they had never heard of the hotel. They seemed unwilling to provide further assistance and suggested I talk to a taxi driver. (Maybe like ours they all speak a foreign language.) Finally I was rescued by an Italian delegate who recognised me as Englishspeaking and we shared a $75A taxi with a driver displaying a 140 km/hr dea th wish on the winding road to M alaga. Even at this point the taxi driver did not know w here the ho tel was and had to stop to ask directions. The conferen ce w as op en ed by the representative of the W ater Environment Federation, Mr Richard D. Kuchenrither, WEF Past President, and a representative of ADE CAGUA Gamaliel M artinez de Bascaran , w ho is also a member of the WEF Executive C ommittee . T he conference was the first organised by the W ater Environment Federation o utside the United States.

First Outside USA All the keynote speakers were from the USA . T hey were: • Dr James C rook , C hair of the WEF Water R euse C ommittee and Director of W ater R euse at Black and Vea tch , Cambridge. • Mr Peter Machno , C hair of WEF R esiduals and Biosolids C ommittee and Biosolids Program Manager for King County D epartment of Natural R esources, Seattle. • Profe ssor Daniel Okun , M ember of

I N

s

p A I N

RT Williams

WEF T echnical Prac tice C ommittee and Kenan Professor of Environmental Engineering, Unive rsity of North Carolina . The conference was organi sed around three concurrent sessions over three days; one session on water reuse, a parallel session on common issues and the third on bio solids. Seven ty-four pap ers we re presented which were publi sh ed in a se t of pro cedures . R efl ecting my interest in water reuse, I attended ve ry few of the bio solids sess10ns. Approximately 50% of the papers were in Spanish . The standard of transla t i on wa s va ried and conse qu ently one's abili ty to follow the presentations and discussions was mixed. One of the main issues to surface at the conferen ce was the differen ce 111 standards parti cularly between C alifornia and Europe and both with Spain. This was a recurring them e throughout the conference and often the subj ect of much lively debate. Like many countries, Spain ha s a large amount of indirect potable and direct irrigation use. However, a significant portion of its wastewater receives minimal or no treatment. To a larger degree Spain has taken on the ' requirements of the 1991-71 EU

Direc tive w hich requires a National Purification Plan by 2010 . However, the sad story is that the country has not been able to implem ent standards for water reuse. At present the situation has progressed as far as a recommendation for a 'guideline' of 1000 fa ecal coliform/ 100 ml for water reu se. Unfortunately this is not being achieved and many farmers in Spain still use raw sewage or water of a lesser quality to irrigate vegetables. By contra st, C alifornia standards require water qu ality that in terms of pathogen s mee ts drinking w ater standards (less than 2.2 total coliform 100 ml) and specify a trea tment process train that basically gives a virus-and pathogen-free produ ct water. The argument in Spain is that this is too strict and that the farmers would simply observe no standard. To have a reuse market in Spain the water must be cheap and consequently minimal treatment is implied .

Public Health v. Economics There is obviously a difference of view on public health policy. In the USA and Au stralia it has not been government policy to set public health goals simply on economics. The WATER NOVEMBER/DECEMBER 1997

19


WASTEWATER argument put forward by the Spanish delegates was surprising given that the country has been prepared to undertake some major investments as evidenced by a desalination plant for potable water supply. The Spanish delegates were very sensitive to the issue of being able to continu e to export vegetables into northern Europe and the potential impa ct of poor sanitation on the tourism market around the Spanish Mediterranean. There was also the suggestion by a Spanish delegate that the Spanish people have an immunity to waterborne disease as there is little reco rded experience of a problem! In attempting to improve the situation . Spain has good intentions but changes always get bogged down.' A similar discussion also took place in regard to the USA and the WHO Guidelines for water reuse. T he WHO guidelines specify 200 total coliform/ 100ml as this ca n b e achieved by maturation ponds. The USA appears to be moving towards zero coliforms: i.e., the achievement of drinking water quality from a bacteriological point of view. In the USA long-term effec ts of organic and inorganic chemicals in the waste stream are not regarded as an issue as drinking the wa ter wo uld be only occasional and incidental. The view of the Spanish and South American attendees was that the WHO Guidelines were better than none and that the USA Guidelines were too strict.

Direct, Indirect or Dual? The second issue that emerged was the different approaches to water reuse , particularly among those who supported dual system s, indirect reuse, or direct reuse. To a large extent the protagonists for indirect and direct use merged into one group and supported the concept of plann ed sys tems with high levels of treatment usually involving activated carbon and membrane filtration. T hey argued that such systems provided a reliable and safe supply while conserving water resources and redu cing environmental impacts from discharges. Those favouring dual system s argued that the long-term health impacts were not known and that dual systems would provide the sam e benefits in terms of co nserva tion of water reso urces and reduced environmental impacts. The fact that 50-60 cities in the USA are now using dual systems was testimony to the fact that they could be economically competitive with expanding on alternative supplies . Those favo uring indirect or direct reuse pointed to the fact that m uch unplanned indirect reuse was occurring and that controlled reuse was preferable. 20

WATER NOVEMB ER/ DECEM BER 1997

Those favouring dual systems argued that much lower levels of treatment could be provided while making the water safe if incidental ingestion took place as the water would meet drinking water standards by being essentially pathogen-free .

WEF Report Bahman Sheikh presented the Water Reuse Committee R eport of the WEF . The report supports indirect potable because water resources are running out, beca use of increa sed pollution control requirements and the expense of direct non-potable reuse. Four proj ects that attest to the value of indirect water reuse are the Lo s Angeles County Sanitation DistrictW hittier Groundwater Replenishment Proj ect, the Orange County Water District Water Factory 21, the Upper Occoquan R eservoir and the El Paso Fred Harvey Proj ect. The four major research proj ects in the USA on indirec t reuse are the Potomac Estuary Experimental Water Trea tment Plant, D enver Potable Reuse D emonstration Proj ec t, the San Diego Total Recovery Project and the Tampa Water Resourc e Re covery Proj ect. Dr James Crook, the Chair of the WEF Water R euse Committee, gave an overview of water reuse issues . One example was the C ity of Santiago in Brazil w hich has a population of more than 10 million. H ere raw sewage is discharged to a local stream which is used to irrigate vegetables. T he incidence of typhoid is 300/100,000. He discussed the following trends in water reuse: • Urban uses • Dual systems • Indirect potable • UV and 0 3 disinfection • M embrane processes • Risk assessment • R egulation development • Integrated resource planning The needed research areas are: • Pathogen inactivation/removal • Effectiveness of chlorine at different TC's (Time x concentration) • Disinfec tion alternatives • Health assessment of parasites • Refinement of microbiological risk assessment methods • Real time in-line monitoring • Identification of organic constituents • Effectiveness and reliability of m embrane processes.

Biosolids A new European Directive prohibiting discharge at sea and the D irectives for higher levels of sewage treatment will increase the amount ofbiosolids by 50-70% by 2005. In Europe there are

not many routes for the disposal of biosolids. There is a crisis of space in landfill s. By 1998 the ocean disposal of biosolids will be banned. Incineration red uces volume but is cos tly and increases air emissions, particularly CO 2 . I attended ve1y few sessions on the subject of biosolids. In the USA now 55% ofbiosolids are benefi cially reused either on land application or as a fertiliser (10%). A Global Information N etwork (R ef: Maq mo) and a Global Atlas of Wastewater Biosolids (Ref: Matthews) have been produced to assist professionals in building on international experience. Public acceptance of the reuse of biosolids would require the production of a consistent quality product that was aesthetically acceptable and provided nutrient benefits. The current practice of mining phosphate and dumping into the oceans through agricultural runoff and through the sewerage systems is unsustainable. In respect to the reuse ofbiosolids in the USA only 10% are distributed and marketed. T he USA EPA R egulation 503 requires the removal of pathogens. A number of processes provide this including composting, alkaline stabilisation and hea t drying. The public is concerned with how the product looks. Drying lends stability and ease of handling. The horticultural use is small w hen compared with agricultural reuse but biosolids can only m ee t 10% of h orticultural demand. Finally there was the challenge to engineers to rethink the treatment issues. For example in the reuse field engineers have been trained to remove BOD and SS. But most water reuse is not concerned with SS and BOD. T he M exican experience is no treatment and engineers need to think in terms of how water will be used and w hat are the risks rather than in terms of facilities, structures and processes. Steph en M yres, President of the European Water Pollution Control Association , spoke about the future role of the Association, w hich represents 24 European country m embers and 40,000 professionals. The Association has a clo se working relationship with IAWQ bu t sees the role of the Association as being more con cerned with guiding m ember countty policies as opposed to the more technical interest of the IAWQ. H e encouraged professional involvement with the Association as that would be a way of influencing decisions in Brussels.

Author Rod Williams is Senior Project Manager w ith C MPS&F Environm ental Brisbane office.


WASTEWATER

The aim of any IAWQ conference is to transfer recent, relevant, technical information across the world. This was extremely well achieved at the 2nd International Conference on Microorganisms In Activated Sludge And Biofilm Processes held at Berkeley University, San Francisco in July. As a wastewater microbiologist and process specialist, I felt that the sciences were finally entering the wastewa ter sector in a capacity that is both required and warranted. Molecular biology was dominant at the conference, w ith many papers discussing the developing application of molecular probes which tell us 'exactly' which bacterial species we are dealing with. Some people had developed new probes, some new pre-treatment steps, some the applica tion of the probes, whilst others reported on other molecular biology technologies that had bee n applied to activated sludge. The inaugural conference on this topic was held in Paris in 1995 and, although successful in its own right, was somewhat condemned for its lack of microbiological content and participating microbiologists , given the topic name. The driving issue was the intrusion of microbiologists in a sector dominated by the wastewater engineer, who for so many years ha s known everything and performed every scientific, engineering and management role that exists. Organisers of this second conference certainly could not be equally accused, with a great cross-fertilisation of minds resulting from the range of technical platform and poster presentations given. Glen Daigger, recognised wastewater guru , noted that as an engineer he was greatly appreciative of the microbiologists who presented their papers in a manner which educated the unadultera ted of the realms and possibilities of microbiology and particularly congratulated those who successfully

trmslated their findings into process useful information. He was pleased to see scientists solving real issues at a treatment plant level. Most presentations related to municipal wastewater treatment, with few addressing industrial strength wastewater. This is probably due to the fundamental nature of the studies being undertaken into the mi crobiological principles of wastewa ter. In the past, no-one cared why microbiology worked-just that it did. Nowadays, operators need to get more from their capital and operate at lower costs. Effluent criteria are also tighten-

8 '

ing and careful operation of biological reactors is required. The social aspect of the conference was also excellent, with international affiliates and students (representing 20% of delegates) well looked after. It was evident that molecular biology will continu e to be a part of the wastewater industry for a long time yet.

Author Therese Flapper is a PhD student in environmental mi crobiology at UNSW and part-time Environmental Scientist with CH2M HILL.

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WASTEWATER

HEAVY METALS LEACHING FROM BIOSOLIDS USING

SULFUR-OXIDISING BACTERIA PR Ginige, A Shanableh · Abstract Solu bili sa tion by bioleaching of heavy m etals from four types of bio solids is reported . In one se t of experiments, elemental sulfur was added as an extra substrate. After acclimation, oxidation of elemental sulfur to sulfuric acid lowered the pH to below 2 in a few days. The process resulted in the following solubi lisa tion results in the different biosolids: Z n , 21-9 1%: N i, 79-96% : C d , 10-79%: Pb, 50-95% : C u , 17-90%: Cr, 34-67%. The bioleaching results were determined using the conce ntrations of metals in the centrifuged and filtered acidic supernatants. The highest m etals leaching results were achieved from the digested biosolids. The process was less effective for the undigested biosolids. The removal of metals after leaching requires separation of the aqueous phase from the bio solids at the low pH. The heavy m etals can be removed from the aqueous phase using lime precipitation. The dewa tered bio solids require neutralisa tion prior to land applica tion.

Key Words Acidification, biosolids, bioleaching, biological treatment, heavy m etals, sulfur , sulfur-oxidising bacteria

Introduction Beneficial use of bio soli ds as a resource is evolving, but the presence of toxic heavy metals has been identified as a major con straint. H eavy metals entering wastewater trea tment systems may originate from a variety of industries, stree t runoff, infiltration through leaking systems and domestic sources. Even though industrial pre- treatment and source control programs can reduce the m etals co ntent of bio solids, biosolids from purely domestic origin can contain significant levels of metals such as copper and zinc (DEH, 1994). Lake (1988) summarised the impacts of applying m etals-laden biosolids on land as follows: 22

WATER NOVEM BER/ DECEMBER 1997

• phytotoxic effects by which yield and growth are reduced or inhibited • zootoxic effects by direct animal ingestion of biosolids on herbage and soil , and by co nsumption of crops containing high levels of toxic metals and • risk to human health through direct ingestion of soil , surface water and gro undwater contaminated through leaching and runoff, and ingestion of foods containing toxic heavy m etals. Many indu stri al co untries have es tablished reuse guidelines acknowledging the benefits of reusing biosolids as a reso urce. The guidelines for agricultural u se are designed to minimise the potential risk to human health and the environment . Su ch guidelines typically specify contaminants thresholds and limit the rate of biosolids application to land for agricultural use. In addition , the guidelines may specify the maximum allowable concentrations of accumulated metals m soils receiving the biosolids. Rawlinson and Samuel (1996) reviewed and summarised the individual states and national Australian biosolids reuse guidelines. Table 1 gives the reported limits on metals in biosolids intended for unrestricted reuse. The levels of permitted heavy metals

for agricultural use in many European countries and the USA were reported by Mininni and Santori (1987). Agricultural land applica ti on of biosolids is probably the most feasible method for final disposal. Couillard and Mercier (1994) evaluated the economics and environmental impacts of the follow ing seven sludge treatment and disposal options: • digestion, metals leach ing, and agricultural use • landfilling • incinera tion • co-incineration • metals leaching, lime stabilisation , and agricultural use • agricultural use of dewatered sludge • agricultural use of liquid sludge. Of th ese options, the authors assesse d the agri cultural use of bioleached biosolids as producing the least environmental impact. They also concluded that the options including metals leaching co uld be competitive. T he application of biosolids to land requires reducing the contaminants to below the threshold limits specified by the relevant guidelines. T he options available for removing heavy m etals from biosolids include chemical leaching, ion exchange and bioleaching. Chemical solubilisation of metals from

Table 1 Comparison of curre nt Australian biosolids guideline li mits (mg/kg) for heavy meta ls New Sout h Wa les Contam inant Arsen ic Cadmium Chromium Copper Lead Mercury Molybdenum Nickel Selen iu m Zinc

Un res•

Rest b

20 3 100 100 150 1

30 32 600 2000 500 19

South Australia Unres•

20 1

Restb

>2 7 >11

-

-

125 150 0.5

>750 >300 >9

Queensland Restb

Unres•

Restb

20 2 200 140 150 1 .5

75 85 3000 4300 840 57 75 420 100 7500

20 3 400 200 200 1 14 60 3 250

75 85 3000 4300 840 57 75 420 100 7500

-

-

-

-

-

60 5 200

300 90 3500

50

>145

60

Source: Rawlinson and Samuel (1996) •unrestricted use contaminant limits brestricted use contami nant lim its

ARMCANZ

Unres•

-

-

-

200

>1400

300


WASTEWATER biosolids at pH 1 was reported . to be effective (Wozniak and Huang, 1982). However, the high cos t, high acid requirements and associated operational problems make the chemical alternatives unattractive (Tyagi et al. , 1988; Wong and H enry, 1988) . In the laboratory h eavy metals were su ccessfully removed from biosolids using magnetic ion exchangers (Swinton, 1987). The ion exchangers extracted the metals at ca. pH 3 within a relatively short residence time of approximately one hour. The ion exchangers were recovered from the slurry by magnetic drum separators , stripp ed by acid , and recycled. Bioleaching of heavy metals from biosolids is a solubilisation process in which the indigenous Thiobaccilli bacteria in the biosolids are exploited to remove the metals. The process was first investigated by Schonborn and H artmann (1978). Later, Wong and H enry (1984) investigated the process in Canada. Bioleac hing has recently gained increasing attention especially by Canadian researchers Qain and T yagi, 1992; Sreekrishnan et al. , 1993) as an environmentally favourable biosolid s decontamination technology.

Bioleaching Mechanisms Biological m etal solubilisation from wastewater treatment biosolids can be achieved by direct and indirect m echanism s. In the direct m echanism , the predominantly sulfide-oxidising bacteria, T. ferrooxidans, oxidise the sulfide component of m etal sulfides according to R eaction 1. M etal sulfides exist in biosolids subj ected to anaerobic digestion. The oxidation of ferrous iron in the bio solids to ferric iron also co ntributes to solubili sation. This proceeds chemically above pH 5, and is mediated by T. ferrooxidans bacteria below pH 4 according to R eaction 2 (Hutchins et al. , 1986). Ferric iron oxidises metal sulfides to metal sulfates, thus contributing to the solubilisation process as in R eaction 3. MS+20 2

T. rerrooxidans )

2f e2++1.5O +3H SO 2 2 4 FeiSO 4 \ +3H 2 O

M 2++SO~- (l ) T. ferrooxidans )

MS+2Fe 3+ ------1 M 2 ++2Fe2 ++s 0

(2) (3)

In undigested or aerobically digested biosolids, metal sulfides may only exist m small q uantities. Accordingly, elemental sulfur or other appropriate substrate mu st be added. Sulfur is oxidised to sulfuric acid in the presence of T. thiooxidan s and T. ferrooxidans bacteria (Reaction 4). The highly oxidising environment and low pH result in an environment suitable for

Table 2 Characteristics of WWTP biosolids Parameter

Sandgate•

Loganb

Oxley Cree kc

Oxley Creekd

23,200 16,100 6.6

20,700 15,800 6.6 7 1210

21,200

88 740 45 924 288 6

130 550 10 3264 594

16,100 12,100 7.8 840 1781 180 539 10 ,1059

11

43 23 16

Total Solids (mg/L) Volatile Solids (mg/L) pH Ammonia Nitrogen (mg/L) Total Kjeldahl Nitrogen (mg/L) Soluble Phosphorus (mg/L) Total Phosphorus (mg/L) Sulfate in Supernatant (mg/L) Zinc (mg/kg•) Copper (mg/kg•) Lead (mg/kg0 ) Chromium (mg/kg•) Nickel (mg/kg•)

95 1262 41 550 95 5035 783 40 29 20 14

Cadmium (mg/kg•)

10 3

18,100 6.8 28 1854

536 118 174

23

93 17

NSW EPAr (1995)

200 100 150 100 60 3

•secondary trickling filter sludge bsecondary biological nutrient removal sludge csecondary conventional activated sludge dprimary and secondary conventional activated sludge anaerobical ly digested "dry solids basis 1class A biosolids (NSW EPA, 1995)

metals solubilisation (indirect mechanism) . The pH reduction in the biosolids is ac hieve d by two major groups of Thiobacilli (Tyagi and Couillard, 1989) : the less-acidophilic and th e acidophili c. The lessacidophilic Thiobacilli reduces the pH to approximately 4. Thiobacillu s thioparns bacteria has been identified as the major organism am ong the lessacidophilic Thiobacilli in the biosolids (Blais et al. , 1993). Thiobacillu s thiooxidan s and T. ferroox idan s are the dominant acidophilic organisms that m ediate biological acidification below pH 4.

: Cu, 65-87% Cd, 79-82% .

C r, 43%

Ni , 35%

Materials and Methods

Acclimation To achieve acclimation of indigenous sulfur-oxidising bacteria, six 250 mL biosolids samples from each treatment plant were transferred into 500 mL sterilised Erlenmeyer flasks. One per cent su lfur (2.5 g) was added to each of three of the six flasks and the other three were used as control samples. T he samples were placed in a gyratory shaker and mixed at 200 rpm at 28°-30° C inside an incubator. The pH was measured every 24 hours. Initial acidification was indica ted by a pH decrease in the samples to below 2. T he experimental design followed Blais e t al. (1992) .

Four biosolids samples were obtained from three wastewater treatment plants (WWTP s) in Brisbane, Queensland: Sandgate (trickling filter); Loganholme (biological nutrient removal); and Oxley Creek (conventional activated and anaerobically digested sludges. The biosolids samples were collected in 20 L drums, and stored at 4°C before use . The initial characteris ti cs of the biosolids are presented in Table 2. T he O xley Creek digested bio solids co ntained the highes t heavy metals content as the plant is known to receive significant quantities of indu strial discharges. The data in Table 2 also presents the NSW biosolids guidelines for unrestric ted use (NSW EPA, 1995), which indicate that the heavy metals co ntent in the bio solids samples exceeded the NSW guidelines. The required degree of metal removal to produ ce biosolids sui table for unrestricted use would be: Zn, 78-96%

Solublllsation 250 mL fresh biosolids samples were inoculated with 5% of the corresponding acclimated biosolids and one per cent sulfur added. T he samples were mixed in the shaker as described above . D aily samples, 20 mL eac h , were withdrawn from each flask and mixed together into one 60 mL sampl e. The same procedure was used for the control experiments. The samples were prepared for heavy metal analysis as follows : each sample was centrifuged at 18 ,000 rpm for 30 min and the supernatant was filtered , then stored at 4° C in plastic bottles. The concentrations of heavy m etals were measured using Piasma Emission Spectroscopy (ICP). Sample digestion for total m etals was conducted according to Test M ethods for Evaluating Solid Waste, USEPA SW-846 (1986). Sulfate was m easu red according to Standard M ethods (1995).

s o+ 1.5O?+H ?O -

-

T. rhiooxid.111s> T. ferrooxidans

H 2 SO 4 (4)

WATER NOVEMBER/ DECEMBER 1997

23


WASTEWATER 8

100

7000

7

8 ...... Cr

Loganholm e - BNR WWTP

6000

--- z n __,._ Cd --0-pH

80 6

:ii!.

5000

5

4000

=4 Q.

3000

-o- pH (Sulfur) __,._ pH (Control)

3

2000

........ Sulfate (Sulfur)

0

-~.,= .::" 5.,

~

!. ~ ~

:i

2

4

3

5

4 3

20

"'

1000

2 0

6

0

Ti me (days)

2

3

5

4

Time (days)

8

20

7000

7

8

Oxle y Cree k

7

WWTP

6000 15

5

4000

Q.

4

-<>-- pH

3000

(Control)

----- Sulfate (Sulfur) ........ Sulfate (Control)

3

2000

(b)

2

~

!. ~ ~

:i

"'

-~

. .::

...... Cr

"'

- - - zn __,._ Cd

~ i 10

-+- Ni ---- cu -lK-Pb

:E :, 0

"'

5

3

Control (b)

2

1000

2

3

4

0 0

5

Figure 1

pH reduction and sulfate production during in itial biosolids acclimation

Results and Discussion Acidification generally proceeds m two steps: an initial decrease in pH to below 4 by the less-acidophilic Thiobacilli followed by a further pH reduction to below 2 by the acidophilic bacteria. Successive transfers of acclimated acidophilic and less-acidophilic bacteria from samples acidified to a pH at or below 2 into fres h biosolids samples accelerate the pH reduction process. For example, the initial acclimation phase required approximately 5-8 days for the pH to decrease to below 2. The su ccessive transfers reduced the time to 3 days in the undiges ted samples but remained unchanged for the digested sample. The anaerobic digestion process may result in the inactivation or destruction of the aerobic Thiobacilli bacteria involved in solubilisation. M etal solubili sa tion pro ceeds through the oxidation of the externally added sulfur (indirect mechanism) and the oxidation of metal sulfides in the anaerobically digested biosolids sample (direct mechanism) to sulfuric acid. As a result of sulfuric acid production, the concentration of sulfates increased and the pH decreased in the treated samples. The fraction of added sulfur (2.5 g) oxidised to sulfuric acid was in the range of 15-23% (0.38-0.56 g), as WATER NOVEM BER/ DECEMBER 1997

= Q.

4

2

"'4

3

5

Time (days)

Time (days)

24

5

--0-pH

e~ .,

0 0

6

C

5000

6

=

= Q.

0 0

5

40

0

(a)

6

:E :,

...._ Sulfate (Control)

2

7

-lK-Pb

60

.,e

"'

-+- Ni ---- c u

Figure 2 Metal solubil isation during initia l acclimation of Oxley secondary biosolids ·

determined by the quantity of sulfates produced (Table 3). The oxidised amount of sulfur that was required to reduce the pH to approximately 2, was 0 .52 g in Sandgate secondary sludge; 0 .38 g in Loganholme secondary sludge; 0.56 g in O xley Creek seco ndary sludge; and 0.40g in Oxley Creek digested sludge. The pH reduction trends m Loganholme and Oxley Creek secondary biosolids refl ected the production of sulfate in the samples (Figures 1a and 1b). In the samples containing sulfur, the pH decreased from approximately 6.6-6.8 to approximately 2 within 5-6 days. In both the biosolids samples, the rate of sulfate production picked up after two days and

remained relatively high thereafter. In the control samples (Figure 1b), the pH decreased from approximately 6.6-6.8 to 4.7-5.1 with the continued digestion. The solubilisa tion rates of the various m etals in O xley Creek secondary bio solids are presented in Figure 2. Except for Ni , the data in Figure 2a indicates a gradual solubilisation trend during the first t'NO days of acidification . The solubilisation rates for all the m etals were the highest between days 2 to 3, reflecting the rapid pH reduction from approximately 4 to 2. Except for Ni, the solubilisation of metals in the co ntrol samples remained relatively low- below 6% . The solubilisation of Ni increased to 19% . The pH in the

Table 3 pH variation and sulfate production during in itial biosolids acclimation Biosolids

Sandgate• Loganholmeb Oxley Creek< Oxley Creekd

Total Solids (g/ L}

23.2 20.7 21 .2 16.1

pH Initia l

6.6 6.6 6.8 7.8

Fin al Control With Sulfur

4.8 4.7 5.1 5.8

1.4 1.7 1.4 2 .0

Init ial

95 45 10 10

Su lfate (mg/L) Final Control With Su lfur

180 130 213 315

•secondary tri ckling filter sludge bsecondary biological nutrient removal sludge <secondary conventional activated sludge dprima ry and secondary conventiona l activated sludge anaerobically digested

6400 465'0 6950 5110

Oxidised Sulfur(%) With Su lfur

21 15 23 16


WA

s T E WAT

100

~ e,_

-~

-

80

~ e,_

20

-~

60

"' 5., s

~

40

40

.,

:E

=

0

"'

0 Oxley - dig . Oxley - sec. Logan. Wastewater Treatment Plant Biosolids

Sand.

~ e,_ 15

a chromium D Nickcl D Zinc

=

0

-

~ e_, 15

Control (b)

Oxley - dig

â&#x20AC;˘copper DCadmium li/.lLcad

C

-~

"'"

~

10

"?. '.l

10

s

.,

.,

:E

Oxley - sec.

20 Con trol (b)

C

5 "'s

Logan.

Wastewater Treatment Plant B iosolids

20

-

20 0

Sand.

~

80

0

0

¡"ti"'

Sulfur (a)

C

60

"'

JOO

Su lfur (a)

""' ~ 5., s

., ~

E R

:E

=

5

0

"'

5

"' 0

0 Sand.

Logan .

Oxley - sec.

Oxley - dig .

Sand.

Figure 3 Solubilisation of Cr, Ni and Zn in t he biosolids samples

control samples decreased from approximately 6.8 to 5.1 following an increase in day 1 to a pH of approximately 7.7. The highest solubilisation results in the control samples were observed during day 1 even though the pH actually increased. An explanation of this trend is not readily available, although it may be that a fra ction of the m etal sulfides in the anaerobic samples may have dissolved as the environment became aerobic . The retention of the original insoluble me tals after five days of bioleaching was in the following order: Cu > Cd > Zn > Cr > Pb > Ni. The final solubilisation results on day 5 were: Zn , 24% : Cu , 17 % : Cr, 67% :Ni, 96% : Pb, 94% : Cd, 23%. The high Pb solubilisation results were surprising, as Pb is typically reported to form strong attachments to organic matter (Tyagi and Couillard, 1987). A summary of the tra ce metals solubilisation results achieved in the different biosolids is prese nted in Figures 3 and 4. The results indicate that significant m etals solubili sa tion results were achieved in all biosolids samples tested . The solubilisation results in all samples containing sulfur were as follows: Zn , 21-91% : Ni , 79-96%: Cd, 10-79% : Pb , 50-95% : Cu, 17-90% , Cr, 34-67% (Figures 3a and 4a) . In the control samples, the solubilisation results were as follows:

Logan.

Oxley - sec.

Oxley - dig.

Wastewater Treatment Plant B iosolid s

Wastewater Treatment Plant Biosolids

Figure 4 Solubilisation of Cu , Cd and Pb in ttie biosol ids samples

Zn, 0.7-4% : Ni, 13-19% : Cd, 0- 3% : Pb, 0-1.3% : Cu, 0.3-3.5% : Cr, 0-2% (Figures 36 and 46). The results indicated significant bioleaching efficiency differen ces between diges ted and undiges ted biosolids. In thi s case high metals solubilisation efficiencies were achieved in the digested biosolids. The metals solubilisation results obtained for the undigested biosolids samples did not meet the required solubilisation levels. However, the concentrations of Cr, Ni, Zn, Cu and Pb in the anaerobically diges ted biosolids were redu ced to below the NSW recommended contaminants levels for unrestricted use (NSW EPA, 1995). For Cd, the process reduced the concentration to approximately 3.6 mg/kg, which is higher than the recommended level of 3 mg/kg. The above reported metals solubilisation results assume 100% separation of the solubilised metals from the biosolids. However, the available dewatering technology cannot completely separate the liquid from the solids. Using centrifuges, Wong and Henry (1984) were able to dewa ter the bio solids to a total solid content of approximately 20% . This dewatering remove s approximately 92% of the liquid and the solubilised metals. The dewatered biosolids must be neutralised prior to land application. The removal

of metals from the leachate can be achieved by numerous methods. Wong and H enry (1984) reported that more than 95 % of the metals in the leachate were removed by lime precipitation.

Conclusions Bioleaching with added sulfur resulted in significant metals solubilisation from all biosolids samples tested. The solubilisation results in all samples were as follows: Zn , 21-91 % : Ni , 79-96% : Cd, 10-79% : Pb , 50-95% : Cu, 17-90% : Cr, 34-67%. The observed m etals solubilisation efficiencies varied depending on the types of m etal and biosolids. There were significant differences between digested and u ndigeste d biosolids. In this case high metals solubilisation efficiencies were achieved from the digested biosolids. For the digested biosolids , bioleaching of Cu, Zn, Cr, Pb, and Ni at ca pH 2 followed by dewa tering achieve d NSW EPA (1995) guidelines for the use and disposal of biosolids products. For Cd, the process reduced tp.e concentration to approximately 3.6 mg/kg, which is higher than the recommended level of3 mg/kg.

References Blais JF , T yagi RD , Auclair JC (1992) Bioleaching of M etals from Sewage WATER NOVEMBER/ DECEMBER 1997

25


WASTEWATER Sludge by Sulfur-oxidizing bac_teria. journal of Environmental Engineering 118 (5) 690-707 . Blais JF, Tyagi RD , Auclair JC (1993) ¡ Bioleaching of Metals from Sewage Sludge: Microorganisms and Growth Kinetics. Water Research 27 (1) 101-11 0. Co uillard D, Mercier G (1994) An Economic Eval uation of Biological Removal of H eavy Metals from Wastewater Sludge. Water Environment Research 66 (2) 32-39. DEH, Department of Environment and Heritage, Queensland (1994) Environmental Guidelines-Sludge Disposal (Draft). Hutch.icns SR, Davidson MS , Brierley JA, Brierley CL (1986) Micro-organisms in Recla1nations of Metals. Annual R eview o[Microbiology 40 311-336. Jain DK, Tyagi RD (1992) Leaching of heavy metals from anaerobic sewage sludge by sulfu r-oxidising bacteria. Enzyme and Microbial Technology 14 376-383. Lake DL (1988) Sludge Disposal to Land. Hea vy metals in Wastewater and Sludge Treatment processes. Vol II-Treatment and Disposal. Lester J N (ed.), RC Press., Inc. Boca Raton, Florida , USA. 92. Mininni G, Santori M (1987) Problems and Perspectives of Sludge Utilisation in Agriculture. Agriculture. Ecosystems and Environmen t18 291-311. NSW EPA (1995) Environmental Management Guidelin es for the Use and Disposal of Biosolids Products. New South Wales Environmental Protection

26

WATER NOVEMBER/ DECEMBER 1997

Authority. Rawlinson L, SamueL E (1996) Overview of Biosolids Guidelines in Austral.ia . Proc. Australian Water and Wastewater Association. WaterTECH Conference (May 27-28, 1996, Sydney, Australia), 47-53 . Schonborn W , H artmann H (1978) Bac terial sewage leaching of metals for sludge European journal of Applied Microbiology and Biotechnology 5 305-313. Sreekrishnan TR, Tyagi RD, Blais JF , Campbell PGC (1993) Kinetics of heavy metal bioleaching from sewage sludge I Effects of process parameters . Water Research 27 (11 ) 1641-1651. Standard Methods for the Examina tion of Water and Wastewater (1995). 19th edn, American Public Health Association/ American Water Works Association/ Water Environment Fede ration, Washington DC, USA. Swinton EA, Eldridge R J , Becker NS (1987) in 'Sewage and Sewage Treatment' Elsevier, Amsterdam. Test Methods for Evaluating Solid Waste, USEPA SW-846 (1986) . 3rd edn, United States Environmental Protection Agency, Office of Solid Waste and Emergency Response, Washington DC, 20460 . Tyagi RD , Couillard D (1987) Bacterial Leaching of Metals from Diges ted Sewage Sludge. Process Biochem.ist1y 22 (4) 114-117. T yagi RD , Tran FT, Co uillard D (1988) Bacterial Leaching of M etals from D igested Sludge (Bioreactor compari-

son), IAWPRC A sian Conference on Water Pollution Control (2nd Water Pollution Control in Asia), Panswad T, Polprasert C, and Yamamoto K (eds.) Pergamon Press, New York, 231-238. Tyagi RD , Couillard D (1989) Bacterial Leaching of Metals from Sludge. In Encyclopedia of Environmental Control Techn ology, Vo l. 3 : Wa stewater Treatment T echn ology (Edited by PN), Library of C hermisinoff Enviro nmental Pollu tion Control Technology, Gulf Publishing Co., Texas 557-590. Wong L, H enry JG<I (1984) Biological Removal and C hemical R ecovery of Metals from Sludges, Proc. of che 39th Indu strial W aste Conference, Purdue University, Lafaye tte, Indiana 515-520. Wong, LTK, H enry J G (1988) Bacterial Leac hing of H eavy Metals from Anae robically D iges ted sludge Biotrea tment System, Vol.II, Wise DL (ed. ) CRC press, Inc. , Boca Raton, Florida ,125- 169. Wozniak DJ, Huang JYC (1982) Variables Affecting Metal R emoval from Sludge. J ournal Water Pollution Control Federa tion 54 (12) 1574-1580.

Authors P R Glnlge is a PhD R esearch Scholar and Dr Abdullah Shanableh is a Senior Lecturer in the School of C ivil Engineering, Q ueensland University of T echnology, 2 George St, Brisbane QLD 4001


Gulgong STW: Blologlcal Treatment Tank (IDEA process) with mechanlcal surface aeration

Henry Lawson , one of Australia's grea tes t poets, was raised in the New South Wales town of Gulgong in the 1860s and 1870s. Formerly a gold mining town supporting a population of some 20,000, today Gulgong is a quiet little village of 2,000 people. The main features include the historic museum, Prince of Wales Hotel and a brand spanking new sewage treatment works that applies reused efflu ent to fields. Okay, so many of the people passing through the tow n wouldn't go to see the works and probably wou ldn't appreciate it, but it is an important facet of the town just the same. Properly trea ted was tewa ter m conjunction with correctly disposed effluent and sludge is the indicator of a modern, affluent (should that b e effluen t?) socie ty . Australia is indeed fortunate to have the fund s for sewe rage infrastructure, unlike m any of the developing cou ntri es which are struggling to support burgeoning populations let alone provide sanitation and cover other environmental aspects. At least the people who attended AWWA's NSW Branch Annual Regional Conference had an opportu-

nity to view one of the cornerstones of Gulgong life. The conference venue was Mudgee, a town of 8,000 people nestling in picturesque hills and a winegrowing region 280 km from Sydney in the Central West ofNSW and only 20 km from Gulgong. Truly a stunning area. But also a region representative of many other areas in NSW-suffering from the effects of drought and attempting to maintain agricu ltural activities. A region thirsty for water. The conference, which also covered trade waste and indu stry, included a forum to consider reuse-whys and wherefores . A site visit was arranged to look at the Gulgong STW and reuse application, courtesy of Carl Peterson, Water and Sewerage Engineer, Mudgee Council. So why would anyone involved with the water indu stry be interested in Gulgong? Could this be a model for other small country towns? Given that the country is in need of water to support agriculture which provides inland NSW with the bulk of its eco nomy, the answer is a definite 'maybe. ' Water rights, including allocation for the aquatic ecosyste m-

environmental flows, and salinity are important iss ues not only for the support of agriculture, but also for the environment. In addition, landuses and irriga tion need to be appropriately prac tised to avoid potential problems such as rising salinity, vegetative loss with subsequent erosion and debilitation of the waterways. These are, of course, far-reaching issues and need to be covered at all levels-local, regional and global. But let's look at local first ... Gulgong.

'Truly a stunning area. But ... suffering from the effects of drought... A region thirsty for water' Gulgong STW currently provides effiuent to Billy Dunn Park, approximately 10 ha of playing fields in the middle of the town . Work is currently under way to implement agricultural irriga tion next to the STW. The area to be used comprises some 40 ha of the 75 ha property , which was purchased by the council for construction of the WATER NOVEMBER/ DECEMBER 1997

27


WASTEWATER STW and reuse application. on a nutrient balance. Pasture At the time of the site visit, produ ction was the recomthe irriga tion was on the m ended enterprise for the brink of commencem ent. site. The ultra low pressure The average dry weather b oom irriga tor was the flow from the STW is 450 preferred option for m 3/day. The STW comprises: di stributing the effluent. • a biological reactor based The layout of the site was on the intermittently extendcarefully planned-the STW ed aeration process processes were sited on the opposite side of the railway • an efflu en t storage/ca tch line from the mo st vocal pond neighbou:r, and the ponds • sludge holding ponds were sited on areas that were • effluent transfer pumps for relatively unsuitable for transferring the secondary pastures . efflu ent to the disinfection So can re use be applied pond (th e site is ac tually everywhere? No. Certainly divided by a railway line) the NSW EPA encourages . • a m aturation pond (15 days the land applica tion of effludete ntion) for disinfection of ent, but m aintains strict efflu ent guidelines w hich require that • an 85 ML storage dam (a monitoring of the proposed spillway from the maturation irriga tion site be undertaken. pond feeds the dam), w hich T his includes characterisaallows storage of efflu ent tion of the site (slop e, during wet weath er and propensity for flooding), periods oflow evaporation identification of soil charac• an irrigation pumpmg Effluent storage dam showing Irrigation pump suction pipes teri stics and depth to station w hi ch tran sfers the groundwater table. stored efflu ent to the travelsioned an irrigation study , which , there are many issues In addition ling irrigation boom. concluded that with careful manageB efore implem enting the reuse m ent the proposed system was sustain- w hich need to be taken into account sch em e Mudgee Co uncil co mmi s- able in the medium to long term based befo re advoca tion of re u se. T h ese include the existing· state of the local waterway, the quality of the effluent, the maintenance of environmental flows to the creek for ecological reasons and the salinity of the efflu ent. Others are the cost of the scheme and funding arrangements , water rights (diverting flow from the creek may disadvantage downstream users) and proposed crop types. Invest in accurately graded, durable media But then Mudgee Council has been from your complete filter media professionals. through all this, and stands to reap the benefits of reuse as well as avoid pollut6 f/04." tion of the local Wyaldra C reek. Mudgee town STW also applies effluent • Decades of mineral processing experience. to land. But that is another story ... • Media produced to the AWWA 8100-89 Standard. .. . There was movem ent at the • An extensive product range at competitive prices. conference for the word had passed around that the stream of efflu ent had • Manufacturing In accordance with Quality System AS 3902/ISO 9002 flowed away. It had joined the oth er • Packaging alternatives to suit any requirement. wild wet droplets ... (with apologies to • Proficient technical assistance and support. the poet) • Prompt delivery Australia-wide and Overseas.

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Author Mitchell Laginestra is Water's NSW Branch correspondent. H e is CMPS&F Environmental's Senior Proc ess E ngin eer, speciali sing m Wastewater Treatment and Odour Control and is based at the Chatswood ' office, Sydney, NSW. [The A WWA Know Your Poe ts Prize (an AWWA tie) will be awarded to the first person w ho faxes us with the discrepancy in this article. (We didn't want the facts to ge t in the way of a good story! -Eds.)]


WASTEWATER

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Abstract A survey of a number of on-site aerobic wastewater systems in So uth Au stralia has revealed a w ide extent of noncompliance with approval co nditi o n s and relevant co des and guidelines. T his fa ilure to comply with the condition s, codes and guidelines can be attributed to a lack of m aintenance. In so m e instances this was coupled with non-compliance of m anufa cture and/or installation requirements. These outcomes were parallel to those of similar studies in N ew South W ales, Qu een sland and W estern Australia. Given that we ca nnot do away with these systems, better m an age m ent of their design , manufac ture, installation, operation and maintenance is essential. Another outcome of the survey was a fact that should be obvious but was not co nsidered w hen the mo nitoring program started. T hat is the well established fa ct that free residual chlorine cannot always be achieved due to the usually high ammonia co ntent of seco ndary efiluent . However, a free residu al chlo rine requirem ent is in eve ry state's guidelines fo r o n- site aerobic wastewater system s. It is the author's opinion that instead of the free residu al chlo rine, total combined chlorine levels should be considered as the criteria, combined with adequate retention time.

TREATMENT A SOUTH AUSTRALIAN SURVEY NM Kayaalp Introduction On-site aerobic wastewater trea tm ent system s such as aerobic treatment units and sand filters provide secondary treatment . After disinfection , predominantly by chlorination, the eilluent or reclaimed water obtained from these system s is considered suitable for irrigati on of dedica ted areas within the boundaries of the property. Primary treatment is usually provided by a septic tank either separate from or within the aerobic treatment unit. It is estimated that more than 3,000 approvals have been given fo r the installation of on- site aerobic units and sand filters in South Au stralia. M ost of these

installations are household units. T he South Au stralian Commi ssion H ealth (SAH C) Standards, as in other states' standards and guidelines, define the design, constructio n installation , operation and mainte nan ce requireC riteria for m ents. reclaimed water quali ty are: • 20 mg/L of BOD 5 • 30 mg/L of suspended solids (SS) • 0. 5 mg/L of free residual chlorine (Cl) • 10 faecal colifo rms (FC) / 100 mL.

Monitoring Study

In 1996 a m onitoring study of on-site (household) aerobic wastewater trea tment sys tem s was ca rried o ut . The first survey was condu cted during the months of M arch/April and the second during August/September. The surveys covered 38 and 37 sites respectively (35 of them being the sam e sites at both surveys) . Seven sand filter system s in the first survey and five in the second were included. The remaining installations were package aerobic treatm ent system s of three brands that are widely installed in South Au stralia. T he selection criteria for the system s surveyed included: • close proximity to the Adelaide metropolitan area for convenience of sampling • occupation ratio of more than 0.4 (where the occupation ratio was defined WATER NOVEMBER/ DECEMBER 1997

29


WASTEWATER as the number of occupants i11- the dwelling p er the rated equivalent population of the wastewater system installed) • agreement by the occupi ers to participate in the survey. The main objective of the study was to assess the compliance of the on-site aerobic wastewater systems against the approval conditions. The assessment included reclaimed water quality, site conditions and maintenance. Other objectives were to evaluate whether there was a need to change the design requirements of the systems to improve their performance, obtain information that would be useful in future policies and strategies, and assess . septic tank inlet and outlet quality with regard to BOD 5 and SS. The temperature, pH , TDS, free residual and combined chlorine of the efilu ent in the pump-out chambers of the aerobic systems were m easured onsite. Temperature and DO of the aera tion chambers were also measured on-site. Samples were collec ted for analyses of septic tank inlet and outlet BOD and SS, aerobic unit/sand filter efilu ent (from the pump-out chambers) BOD, SS and faecal coliform (FC). Analysis for NH 3 was added during the first stage of sampling. The laboratory analyses were carried out by the Australian Water Quality Centre. Site inspections and interviews with the occupiers/owners of the premises were carried out parallel to the on-site measurements and sampling.

Study Outcomes The maj ority of the systems surveyed did not comply with th e required standards for reclaim.ed water quality, site conditions and maintenance. Septic Tank (Primary Treatment) Results The inlet and ou tlet readings for BOD and SS are summarised in T able 1, w hich clearly indica tes the large variation in the data, especially for the septi c tank inlet. As the sampling techniqu e was improved during the second stage of monitoring , som e extreme readings at the inlet du e to sc um contamination of the samples were eliminated. It is worth noting that the septic tank outlet data for both SS and BOD are w ithin acceptab le/

expected levels, .e xcept for one reading of very high BOD (1360 mg/L), which was sampled only during the second survey. This was at a site with problem s from the source. Reclaimed Water Quality Produced In each survey only two system s, or about 5%, co mplied with the SAHC reclaimed water quality criteria. Thirteen units or 34% in the first survey, and 10 units or 27 % in the second survey complied with the reclaimed water criteria considering the BOD, SS and FC requirem ents but not the free residual chlorine requirement. On the other hand , considering only BOD and SS, 25 units or 66% in the first survey and 19 units or 51% in the second survey were efficient . In other words, the units performed relatively better as secondary system s (BOD and SS removal) than for disinfection. The res ults from warmer m onths (first su rvey) we re slightly better than those fro m colder months. Site Conditions The site inspec tion results also indicated the non-compliance of most of the systems surveyed with the SAHC requirements. These non-compliances included : • lack or minimal stocks of chlorine tablets • chlorine tablets sticking in canisters • inoperative aera tors • broken internal pipe systems in the aerobic units • displaced media • exposed electrical wiring • restricted access to deep pump sumps, especially those with sand filters • irrigation areas near playgrounds or w here vegetables were grown • irrigation of a neighbouring property (vacant land) • irrigation areas within 50 m of creeks • irrigation areas with more than a 1 :5 slope • unburied pipework • holes made in the pipe instead of installing sprayers or drippers • absence of sprayers or drippers • spray drifts • signs at only three sites in the fi rs t survey indicating that reclaimed wa ter is used for irrigation and should not be consumed and at only four in the

second survey • breeding of mosquitoes and other insects • odours. It was also noted that new home owners do not give high priority to establishing and locating irrigation areas in accordance with approval requirements. A 'not-considered' Outcome: Free versus Combined Chlorine One very important outcome was that the free residual chlorine levels required by the guidelines were not achieved for about 95% of the system s monito red . On th e other hand , as indica ted earlier, if the free residual chlorine require ment was not considered , 13 sites or 34% in the first survey, and 10 sites or 27% in the second survey complied with the reclaimed water criteria. It should have been obvious that the high ammonia and Total Kjeldahl Nitrogen (TKN) content of secondary domestic was tewater efflu ent would exert a high chlorine demand, and that the treatment/aeration provided is usually not sufficient for nitrification/ denitrifi cation. This cam e to the author's attention only after th e problem s encountered during the titration for measuring free chlorine levels 111 the first stage of the study. Consideration was then given to NH4 + levels and break point chlorination. In th e first survey, secondary efflu ent samples from 12 sites and in the second survey all the secondary efiluent samples were analysed for NH4 + in addition to the other parameters monitored . When ammonia comes into contact w ith C l 2 combined chlorine compounds, mono chloram.ines, dichloramines and nitrogen trichloride are formed. The ammonia in the secondary efiluent exerts chlorine demand at the theoretical ratio of7.6 C l2 to 1.0 NH3' In addition to ammonia, the organic constituents in wastewater will react with C l 2 and Fe•+ , Mn++ , H 2 S are oxidised. Free residu al chlorine is achieved only after the chlorine demand for oxidation of organic and other constituents and the ammonia demand , known as break point chlorination, is satisfied . Bactericidal effec ts of total combined chlorine are know n to be equal to free chlorine, with extended

Table 1 Resu lts for septic tank BO D and SS Septic tank in let

B0 D5 mg.I L

I

Septic tank outlet

SS mg.I L

B0 D5 mg.I L

SS mg.IL

Ave rage

Maxi mum

Minim um Average Maximum

Mini mu m

Average

Maximum

Mini mum

Average

Maxi mu m Min imum

Survey 1

952

5750

7

2850

22600

19

155

550

8

145

610

18

Survey 2

216

1280

10

162

799

13

207

1360

10

122

488

17

30

WATER NOVEMB ER/ DECE M BE R 1997


WASTEWATER

Sample bottles at the back casing for the air blower. The tank lld Is open

contact time (Metcalf and Eddy, 1991 ). As listed above, one of the main four parameters considered in every state's guidelines for reclaimed water quality is the free residual chlorine content. This is usually required to be >0.5 mg/L. In some guidelines an upper limit of 2 mg/L is also recomm ended. To summarise the effect of ammonia on chlorination of secondary efflu ent, Table 2 compares the results of the SAHC monitoring study with the disinfection and microbiological data from two township WWTPs, Heathfi eld and Hahndorf, w hich receive mainly dome stic sewage. These are both extended aeration systems (SA Wastewater Treatment Plant data , 1995). The data in Table 2 for both the township plants and on-site systems

Inside an on-site aerobic wastewater treatment unit. Note the two chlorine containers on the left

indica te that higher levels of ammonia make it difficult to achieve free Cl residual. Among the on-site sys tems monitored, at the sites that free chlorine levels criteria were actually achieved, NH 3 levels were low-between 0 .14 mg/Land 3.87 mg/L-compared to the average values of 20 and 28 (and a maximum of105) mg/L NH 3 . The data in Table 2 also shows a better correlation betwee n achieving disinfection (i.e. m ee ting FC cri teria) and the presence of total combined chlorine than with the presence of free residual chlorine. It should be noted that for the 'average' on-site unit to achieve free residual Cl, theoretically (20 to 30 NH3) x 7.6 mg/L = 152 to 228 mg/L C l needs to be dissolved in the disinfection

Table 2 Compa ri son of ammonia , free chlorine, combined ch lorine and FC

Ammonia

Heathfield

Hahndorf

Survey 1

Su rvey 2

Range mg/L

1 -29

0.01-34

0.14-63

0.64-105

Median mg/L

-

-

19.1

21.9

Average mg/L

Free Cl

Range mg/L Median mg/L

15

10.8

20

28

<0.1-2.6

0 .1 -5.2

0-5

0 -5

-

-

No. of readings 28 out of 52 30 out of 52 (Criterion: >0 .5 mg/L) complied

Combined

Range mg/L

Cl

Median mg/L

No of readings (Criterion: >0.5 mg/L) complied

FC number Range mg/L (Criterion:

Median mg/L

< 10 per 100 ml)

No of readings complied !l J

0.2- 7.5

0.1-5.5

0

0

3 out of 27

2 out of 30

0-16

0-5

0.17

0 .32

5 out of 52

3 out of 52

18 out of 27

14 out of 30

0 -6

0-10

0-36 000

0-1.3x10 6

-

-

107

440

51 out of 52 49 out of 52 15 out of 27 (38) 13 out of 30 (37)

Note (1) In the first survey 11 out of 38 systems, and in t he second, 7 out of 37 systems had no Cl tablets in the disinfection chambers.

chambers monitored. It seems unlikely that this level of dissolution of chlorine tablets in the disinfection chambers of those system s can be achieved. It is wo rth no ting that at the township WWTPs the chlorine dose applied is usually only 10- 15 mg/L. Free chlorine residual is not considered a criterion, and in m:iny cases, as show n by the data , the presence of combined chlorine was sufficient to achieve low FC levels.

Discussion The outcomes of the monitoring study, similar to those obtained by various studies carried out interstate, were that there was a great extent of failure to comply with reclaimed water quality , site conditions and maintenance requirements . Current guidelines are being revised and updated in several states including an Australian/New Zealand Standard draft on the de sign , construction , maintenance and operation of on-site aerobic wa stewa ter treatment units. The following issu es shou ld be addressed in the new guidelines: • there should be more details on design requirements, e.g. aeration methods , treatment parameters , clarifier surface loading, depth , detention times, separate chlorine contact and pump-out chambers • a total combined chlorine requirement should be considered rather than the current free residual chlorine requirement in the reclaimed water. Further consideration should also be given to detention times • other disinfection methods • more emphasis on site assessment • more emphasis on maintenance WATER NOVEMBER/ DECEMBER 1997

31


WASTEWATER • m ore emphasis on increasing h ome ow n er awareness • testing programs sh ould b e required before approvals are given • more detailed assessm ent procedures taking into account evapotranspiration , climatic and soil condition s • alternative treatment and disp osal system s. Councils should b e en couraged/ supported/ required to h ave a b etter monitoring role during the app roval and installation stages as well as in the maintenan ce and operation of the onsite was tewater systems in their areas . An important issue that n eeds to be addressed is increasing the aw aren ess of home owners/occupiers about their on. site system s and their requirem ents. In addition , policies should b e developed

to deal with the existing (installed) system s that are n ot complying with the curre nt and/or updated standards. In spite of p roblem s related to the constru ction , installation , operation and m aintenance of on-site system s, these system s, w h ether they be conve ntion al, aerobic or n o n- co nve n tio n al, w ill contin ue to h ave a significan t role in was tewater trea tmen t, as there is a continuing shift towards localised trea tm ent w orldw ide (T ch ob anoglous, 1996) . D esign , evaluation , op eration and m aintenan ce requirem ents of onsite aerobic was tewater system s n eed to b e reviewed , together w ith em erging alternative system s. There is a need to h ave a broader p ersp ec tive on on-site was tewa ter sys tem s, b ecau se th ey w ill play an

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Acknowledgements T h e author greatly values the w ork of T ony Farrar and N eville Pash of the SAHC's Environmental Waste Unit, w ho carried o ut the ac tual field w ork. Special thanks are also due to the AWQ C for assistan ce with the on-site analyses procedures, loan of the DPD on-site chlorine determination kit.

References Australian Water Quality Centre (1996) SA Wastewater T reatment Plant Data. Draft Australian/New Zealand Standard DR 96034 (1996) (revision of AS 1547-1990). Department of Health, NSW (1996) R eport on the Survey of Aerated Septic Tank Systems. Department of Natural R esources Queensland (1996) Preliminary Draft for Authorisation Criteria and Procedures fo r Authorisation of Onsite Wastewater Treatment Plants. Devine B, Survey ofOnsite Systems in Perth. Presenta tion at the 2nd National Workshop , Onsite Sewage Treatment Systems, 13-14 March 1997, Sydney. Draft Guidelines Ae rated Septic Tank Systems Environmental Health Officers Manual (1994), Department of Health NSW. Environment Protection Authori ry, Victoria (1996) Draft Guidelines fo r Alternative Wastewater T reatment Sys tems, Best Prac tice Enviro nment Management Series . Hulse M, Survey of Onsite Systems on the Gold Coast. Presentation at the 2nd Na tional Wo rkshop, Onsite Sewage Treatment Systems, 13-14 March 1997, Sydney. Kayaalp NM, South Australian Perspective . Presentation at the 2nd Nati onal Workshop, Onsite Sewage Treatment Systems, 13-14 March 1997, Sydney. Khalife MA and Dharmappa (1996) Aerated Septic Tank Systems: Field Survey of Performance, Water, Australian Water and Wastewater Association, Sydney. South Australian Health Commission (1995) Standards fo r the Construction, Installation and Operation of Septic Tank Systems in South Australia. Supplement A: Aerobic Sand Filters. Supplement B: Aerobic Wastewater T reatment Systems. South Australian Health Commission.

Author

Pemh G/es

Trend View

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WATER NOVEMBER/ DECEMBER 1997

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N Mehlika Kayaalp is a Senior Public H ealth Engineer with the South Australian H ealth Commission . She is B Sc, C ivil Eng . (Ankara/Turkey) ; M.Eng., Sanitary Eng ., (D elft/ the N etherlands); and M. Phil. Environm ental Sci. (Murdoch Uni. /WA). She h as w orked in the engineering and research areas for several public organisations, unive rsities and priva te consultants in Turkey, Sw itzerland , W estern Australia and South Australia .


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Abstract This paper presents a summary of a research report on California's water system which suggests that the practice of governments providing water to consumers should b e reconsidered, since private companies can provide this same function without subsidies or tax exemptions. The report argues that California and other American states should adopt policies that encourage the termination of government provision. These policies would have minimal impact on consumers, the report asserts, since the price of water should be approximately the same for the two types of provider. Moreover, the revenues generated by terminating the public water companies could be used to reduce taxes or to fund other, higher priority government programs. However, the report cautions that the contracts must be well structured.

Introduction Who should supply consumers with water? A study conducted in 1996 by a public-policy research body, the Reason Foundation of USA, compared the performance of private and public water companies in California to gauge the potential benefits of restructuring the industry. The study, Restructuring America's Water Industry: Comparing

BUSINESS

Investor-Own ed and GovernmentOwned Water Systems, examined tax subsidisation, the cost of capital, water charges, operating costs, investment income and capital expenditure. The Californian report is particularly relevant to the current Australian situation , where many government bodies are being considered for privatisation or corporatisation. Especially relevant are public utilities, including water authorities, which many consider should not be handed over to any form of private management. Although California is considering some sort of restructuring, a comparison of the private and public water companies in its current water supply system can offer some interesting and useful insights. This paper examines some of the issues raised in the report.

Importance of Restructuring Increasingly, countries have restructured, or are currently restructuring all or part of their water delivery systems to realise private sector efficiencies. The most notable for their worldwide influence are the United Kingdom and France, w here nearly 100 per cent and 75 per cent of the population respectively are served by private water companies . The British and French companies compete worldwide in a rapidly growing market for the design,

building and operation of water and sewerage systems. Would the United States of America, and California in particular, benefit from similar restructuring? Currently, private water companies serve approximately 15 per cent of the US population and 22 per cent in California. The remaining population receives its water from public water companies, which receive generous tax subsidies at the local, state and federal level and are not subj ect to market pressures such as the threat of acquisition, the interests of shareholders or the risk of bankruptcy. Operating m a highly insulated environment, the public water companies do not have the same incentive systems to promote efficient delivery of services as the private sec tor does. The question of how water should be delivered is at the heart of the controversy over the role of the government with respect to a natural monopoly in a freemarket economy. Arguably, the most efficient delivery of water services in a given geographical area is,accomplished by having a single provider. The question is therefore whether public services with these characteristics can be more efficiently financed and operated by private or public authorities. Many of the theoretical issues relevant to this debate have been WATER NOVEMBER/ DECEMBER 1997

35


BUSINESS pay their costs 9f capital (interest on debt). Further, the public companies have low operating earnings due to their significantly higher operating expenses and depreciation costs. They do not fo cu s on streamlining operations becau se they are guaranteed a constant supply of income from local property taxes and connection fees. They are also exempt from local, sta te and federal taxes and do not have to pay dividends. On the other hand, private companies face high levels of taxes and interest payments and have stockholders who desire a competitive 'The Californian report is extremely useful level of dividends. This requires them when discussing the advantages and to reduce costs disadvantages of corporatisation and whenever po ssible to genera te revenue privatisation in Australia' to meet these expenses. not the publi c industry should be liquiThe US study also found that both dated. This subject has been largely priva te and public companies had ignored for a number of reasons includ- almost identical stream s of operating ing the fear of job loss, reduction of the revenue, so that converting public to income of service providers and consul- private utilities would yield efficiencies tants and the loss of political contribu- in operation ofUS$104 per connection. tions , power and elective positions. It is It can be concluded from the study as if public water companies are adopt- that private-sec tor efficiencies are ing defensive strategies renliniscent of substantial enough to allow private those of the 1980s corporate managers companies to service California's water designed to stop takeovers from occur- customers without increasing water ring and to protect their own jobs. rates, while still paying US $4 1 per The Californian report is extremely co nnection annually in taxes and useful when discussing the advantages freeing up scarce public resources for and disadvantages of corporatisation and alternative investments. privatisation in Au stralia, given the A close exanlination and comparison varying approaches of water reform in of the operations of a represe ntative this country. T he study compared the sample of private and public water operations of the three largest private purveyors in California found that water compan ies in California with that private water companies provided of the large public water company comparable water services to consumers servicing Contra Costa and Alameda at the same price as government wa ter Counties. The figures for the three companies, even though they paid taxes private water utilities used for the and did not receive extra non-operating study-California Water Service income. Government water companies Company, San Jose Water Company received generous tax subsidies that and Southern California Water could be used to fund other governCompany-reflect the state of the ment projects and higher priorities . whole private water market in T he cost of capital was found to be California since toge ther they service higher for public water companies than abo ut 60 per cent of all cu stomers for private water companies. T he served by private companies or approx- private companies were significantly imately 12 per cent of California's total more efficient in terms of revenu e in water customers. their operation of water services than government water companies, which Comparison of Private and received a substantial amount of income Public Water Companies from high levels of cash and investThe most significant result of the m ents. It appeared likely that governCalifornian study is that private compa- ment water companies h ad higher nies rely primarily on operating capital expenditures than priva te water earnings to meet taxes (property and companies. The results of the study suggest that a income) and service the costs of capital (interest on their debt and dividends to restructuring of the US water industry stockholders), w hereas public compa- to take advantage of the beneficial nies rely completely on non-operating effects of private market pressures is in sources of income such as property tax the interests of the general public. The allocation and investment incom e to delivery of comparable wa ter services by

covered in professional and acad~nlic journals, but there have been few empirical studies comparing the performance of the two structures. Methodologically, there are a number of barriers, including the absence of common accounting standards and the subtle effects of subsidisation, that make comparisons using traditional m ethods difficult. Important participants in the public water industry such as employees, investment bankers, lawyers , brokers , accountants, engineers, consultants and elected board members have differing views as to whether or

36

WATER NOVEMBER/ DECEMBER 1997

private companies, even with higher non-operating costs, is possible because the financing and operation of water services by the private sec tor crea te stronger incentive systems for cost reduction and efficient resource allocation. T he study suggests the institutional environment of a private company provides incentives for managers that are in the best interests of the general public. The study demonstrated that the private sector oper tes and finan ces water utilities more efficiently than the public sec tor. It remains unclear whether private companies, given the current regulatory environment, invest a sufficient amount in capital improvements to meet proj ected long-term needs. The re sults of the study suggested that public companies spend more on infrastructure. How much of this difference can be explained in terms of differences in efficiencies between public-sector and private spending? Theoretically, private companies deternline infrastru cture based on demonstrated need , subject to cost-benefit analysis and return-on-investment criteria. While the results of this study have direct implications for the operation and financing of water systems, they do not necessarily meari that California's water assets should be sold. There are a number of models on which restructuring could be ba sed, including the French franchise model, in which private water companies do not own the plant and equipment, but only own the right to operate it for a specified amount of time. T he most appropriate model for restructuring should be a topic for future research .

Regulatory Issues The Californian report illustrates that the private sector could be more efficient if rate-of-return, favoured by the California Public Utilities Commission (CPUC) , were to be replaced with a system of price caps similar to the ones adopted in the United Kingdom and France and beginning to be adopted by US local governments for regulation of the waste indu stry. The bes t evidence of the failure of the current regulatory framework is the inability of the US water industry to compete internationally. The French model is donlinating the world market in the development of new water systems and ~n American presence in the international sphere is virtually non-existent. This juxtaposition has occurred because the United States has developed a totally subsidised public sector alongside a private sector, regulated on a rate-of-return basis, that is dominated by cost-plus type thinking.


BUSINESS The regulatory environment do.es not foster the creation of large, efficient water companies structurally designed to compete in international markets. Aside from eco nomi c regulation , restructuring brings environmental and health regulations to the forefront. In California, environmental regulations on water use already apply to both private and public water companies . The statutory authority is in place for these boards to administer the wa ter industry fully. The question is whether they decide to exercise this authority. British water companies provide both water and sewerage services and these are regulated by the same regulatory authority. In California , even though the regulatory framework for wa ter and sewerage system s has already been consolidated, the two functions are still in mo st cases provided by separate public water and sewerage companies. Now, the state government is prodding public water companies to perform as integrated units. It was similar balkanisation of authority that was one of the motivators of similar changes in the British water system s. Critics of private water companies often argue that, even if they face the same standards as public companies, the profit motive inherent in private ownership gives managers an incentive to cut corners on health regulations. This argument is both theore tically flawed and empirically incorrec t. T heoretically, there is no economic incentive to ignore such regulati ons because the regulatory framework itself allows fo r cost recovery on expenses incurred in complying wi th wa ter standards. Empirically, altho ugh no compre hen sive study has bee n complete d compari ng public and private sector compliance with water quality standards in California, there does not seem to be a difference in water quality standards between the larger private and public water compa. nies. Indee d , the hi storical record indicates that public companies have been less likely to comply with environmental and health standards th an the private sec tor in a wide range of policy areas. Public water companies are more likely to use their political leverage to fight stringent standards on w hatever service they provide. In addition , the regulating agency has a more difficult time in forcing public companies to adopt the costly policies necessary to meet their standards. While the government can tell private companies to cut their dividends or operate with less profit, public companies often demand increased subsidisation, and thus in crease d taxes, to support any improvements. Since it is politically

unpopular to _raise taxes , politicians have been known to seek alternatives to enforceme nt. The United States has the worst of both worlds-a government-controlled regulatory stru cture that has limited regulato ry authori ty over other governm ent agencies. Therefore, if a public policy is not properly pursued by one governmental agency to the satisfaction of ano ther agen cy and the public perceives it is not being well served , the government merely blames the government for its inadequacies.

Public Accessibility

Answers to these ques tions will change over time as environmental, financial and political conditions change. Institutions that were once the most efficient mechanism for solving a parti cular problem often persist , embodying the ideas, power relations and political compromises of the time of their creation. The provision of water services by the numerous qua siautonomous public companies, each with its own engineers, lawyers and governing boards, 1,11ay once have been the bes t solution to the perennial problem of wa ter distribution in California. If they have now become anachronism s, progressive public policy mu st facilitate the creation of a new institutional framework for the provision of water services. The lesson from privatisation worldwide is that a transparent and competitive process for the provision of services

It is importan t that the public perceives that a forum exists fo r input on public policy issues involving water. In California the argument can and will be put forward that elec ted and appointed boards of the public water companies give the public this access. There are alternatives for public access such as 'The lesson from privatisation worldthe CPUC and the wide is that a transparent and competiState Water R esources Control Board. These tive process ... can achieve higher government agencies quality provision at lower cost, but only may be funded by a on the surcharge if the contract is well structured.' consumer's water bill so their ability to regulate and provide for on assets w hich may still be in the public input is not frustrated by the public domain can ac hieve higher general budget constraints of the state quality provision at lower cost, but only government. if the contract is well structured. There are plenty of examples w here the Conclusions co ntract has provided only minor The report on California 's wa ter advantages because the overall structure companies concludes that any discus- of the private contract failed to allow sion abo ut reforming the structure of competitive provision of services across the wa ter industry must include options a state-owned grid. There are a number for the restructuring of the industry of cases w here cu stomers and the using the taxable market for capital and government have paid dearly for private the performance accountabili ty of the sector provision of services sold on priva te sector. contracts to public utilities w hich bury Water marketing has been suggested the extra and typically higher unit costs as a solutio n to the problems of in the total cost structure. California's wa ter, but it will not work so long as there is a strong government- Reference subsidised wa ter industry no t subj ect to R eason Foundation, 1996. Restructuring market pressures . When a subsidised America's Water Industry: Comparing water industry does not have to respond Investor-Owned and GovernmentOwned Water Systems, Policy Study No. to market pressures, there is little 200, 3415 S. Sepulveda Blvd, Suite 400, motivation to allo cate resources Los Angeles, CA 90034. efficiently. Not much attention was given to the importance of public policy in the Author Bronwynn Adamson is a Lecturer report. It is important to ask several questions about any institutional frame- at the D epartment of Commerce at work fo r the delivery of water services: the Au stralian National University, • How does it affect water quality? Canberra. She ha s a Master of • How does it affect environmental Economics degree from Ithe Universi ty . goals? of N ew England, Arm1dale , where • H ow efficient is it in financing water she wo rked in the D epartment of infrastructure for the future? Accounting and Financial Adminis• How effi cient is it in operating water tration and at the Centre for Water system s? Policy and R esearch . She is currently • What is the optimum method to undertaking Ph.D studies in the area of regulate the delivery of water service? privatisation of water authorities. WATER NOVEMBER/DECEMBER 1997

37


ENVIRONMENT pumped out into a reed bed which runs down the side of the house and feeds into the main reed bed.

Drinking Water System The potable wa ter system makes use of specially designed gutters which segrega te rubbish from water and pass over a first-flu sh coll ector, so sedimentladen initial volumes are stored for dumping and only; the later flow is collected in a 10,000 L underground tank. Sydney is very differen t from Adelaide/P erth-even M elbourne! A computer model run by the University of Tech nology in Sydney predicted that, based on the characteristics of the system and the reasonable regularity of Sydney's rainfall, shortfalls of drinking water are likely about two to ten times per year , depending on in-house consumption , and surplu ses are going to be more common than that. The m odelling suggested that co mple te independence would require a 100 cubic metre tank, which is impossible on the site. Although all appliances in the house are low-flow units, nothing exceptional has bee n installed and there is a di shwas her, front..'.loading washing machine and all the other basic appliances . Using recycled effluent for clothes washing presents something of a challenge when the sewage treatment plant is not working optimally, a situation which prevailed w hen I visited the house in May this year. Michael and H eather would like to be able to install a reverse osmosis unit and derive drinking water from the effluent to back up the tank supply.

When Michael Mobb s and H eath er Armstrong renovated th eir inner-west Sydney terra ce house th ey made a commitment to becoming sustainable in terms of water and en ergy. The size of th e house and block (71 square m etres of roof and 130 square metres) made this commitment a significant challenge. I visited th e house in Ma y and found that they seem to have met th e challenge. Aiming to be entirely independent of the Sydney water and sewerage system, H eather and Michael elected to collect all their roof water for drinking and to direct all their stormwater into a reed bed that evapotranspires the water.

Sewerage System Sewerage is via a normal flu shing toilet that joins all the other wastewater from the house and passes through a prototype Dowmus trea tment system. \

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The system consists of three stages of filter and contact media over w hich the sewage flow is flu shed. A mixed flora from bacteria up to worms brea ks down the waste and the purified effluent is sto red in a sump. On demand , a pump extracts water which is passed through a UV disinfection unit before being used for toilet flu shing, garden wateri ng or clothes washing. If the accumulated effluent exceeds the storage capacity, it is simply /'

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The roof of the C hippendale house is all but covered by a total of 18 solar panels and they are linked to the state grid in such a way that surplus energy is sold into the grid during the day, but power is bought in during the night.

UTS Monitoring The performance of the house and its systems is being closely monitored, thanks to the support of Professo r Geoff O 'Loughlin and his tea m at the University of Technology in Sydney. The initial modelling will be compared with ac tual performance in term s of water balances and the qu;ility of drinking water and efflu ent is closely monitored. Early indications are that,

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ENVIRONMENT despite the ve.ry urban setting, roof water quality is very good . Overall, the initial impression of this new project after about five months online is that the ambition to be selfreliant for drinking water, at least for most of the time, is quite realistic. The real environmental benefits of preventing all stormwater discharge from the site, rather than protecting quality and cutting peaks, are not really clear, but the record to date is that only one storm has actually exceeded the system's capacity.

Future Looks Good

Corner of the house showing first-flush dlverter and reed bed for surplus water

The site is very tight in every respect and this places considerable pressure on the sewage treatm ent system , the reed beds, and the family to coexist successfully . Since the D owmu s sewage treatment system is a prototype, its longterm performance has yet to be prove n , but it is admirably simple and has considerable volume, a luxury which most commercially available on- si te treatment systems do not enjoy. Overall, the Mobbs-Armstrong proj ect for a sustainable urban hou se is ambitious but laudable and the experien ces gained will be valuable for everyone w ho has a stake in managing urban systems better.

GUY PARKER AWARD The annual Guy Parker Award for the best paper published in Water between May/ June and March/ April has been awarded to the paper The Pollutec Stormwater Pollution Trap: Field Trials by RA Allison, TH F Wong and TA McMahon, which was published in Volume 23 , No. 6 (November/ December 1996). The paper, which describes the monitoring of an Australian invention which has now entered the global market, was chosen for its originality, relevance and presentation. Th e $500 award commemorates the memory of Guy Parker, who played a major role in forming AWWA in 1962 and made significant contributions to the affairs of the Association as a member, federal president and honorary secretary/ treasurer. Guy Parker was the foundation chairman of the journal committee and was responsible for the planning and development of Water until hi s sudden death in 1981.

BIOBLOCK® Revolutionises Current Treatment Practices ADVANTAGES: • Inert Polyethylene Construction • Guaranteed Long Life of Material • Rapid Biofilm Development • Easily Installed • Large Surface Area/m 3 • Non-Clogging Guarantees Results • Self Supporting and Strong (12 ton/m 2) • Replaces Inferior Media AgentorTradeEnquiries:

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41


ENVIRONMENT

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ENVIRONMENTAL REGULATION OF PERTH'S GROUNDWATER

Abstract The capital city ofWestern Australia, Perth , overlies a significant unconfined groundwater reso urce which is used both for potable supplies and horticultural purposes. The aquifer also supports valuable wetlands. This paper sunrn1arises the impacts of urban development and pollution on the quality and quantity of thi s resource and then outlines the suite of mechanism s, both established and new, w hich are being employed by the Wes tern Australian Department of Environm ental Protection (DEP) to improve the management of the groundwater.

Key Words Groundwater , wetlands, environment protection, waste manage1n ent, landfills

Introduction Perth is uniqu e in Australia in that it overlies a significant gro undwa ter reso urce that is unconfined, of high quality and close to the surface. T he superficial groundwater resource exists because of the occurrence of unconsolidated sup erficial sa nd s that are extremely permeable and porous and enable the storage of large quantities of water. It is the combination of both proximity to the surface and soil type which makes groundwater abstraction economically and strategically valuable to Perth. However, this combination also renders the so urce extremely susceptible to pollution. Most of the rainfall on the coastal plain does not form surface runoff but infiltrates to the superficial aquifer. A fea ture of this aquifer is that it tends to discharge at a slower rate than it 42

WATER NOVEMBER/ DECEMBER 1997

rec harges. This causes a mounding effec t which is particularly evident north and south of Perth at the Gnangara and Jandakot Mounds . (Figure 1) These mounds , some minor mo und s and the deeper confined aquifers provide 70% of Perth's public and private water supply. This includes 45% of the potable public water supply. The variable topography of the coastal plain , the limited surface drainage and groundwater mounding have created numerous wetlands on the Swan Coastal Plain where the groundwater table reaches the surface. These wetlands are the most biologically productive areas of the Swan Coastal Plain and directly or indirectly support most of the wildlife. Even where the +-

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groundwater is just below the surface many trees rely on saturated groundwater to overcome the lack of unsaturated soil moisture. In terms of linking environmental and groundwater protection on the Swan Coastal Plain the issues to be addressed are protecting groundwater and wetland water quality from point and diffuse source contamination, managing water levels so that wetland ecosystems are protected and protecting wetland, vegetation and fauna that are dependent on groundwater.

Point Sources of Groundwater Contamination Point sources of contamination commonly affect the shallow groundwater of the Perth metropolitan region and occur at localised sites of waste production or disposal or at sites of chemical spillage . More than 1,000 sites h ave been identified on the Swan Coastal Plain that are ranked from high to low risk to the environment or population depending on their toxicity, volume, material or location. The main types of contaminated sites were identified as: • industrial waste sources such as metal finishing shops , foundries , drycleaners • chemical-based waste sources such as chemical and pesticide manufacturers , refineries and fu el depots, service stations • landfill sites such as domestic waste disposal and industrial landfill sites • liquid waste disposal ites such as sewage treatment plants , septage • animal-based waste sources such as abattoirs, woolscours, piggeries • food-prod uction waste sources such as starch production, breweries • cen1eteries . The highest risk sites are the indus-


ENVIRONMENT trial and chemical point sources mostly concentrated in zoned indu strial areas, 111 particular, Kwinana , but also .Canning Vale, O'Connor, O sborne Park and W elshpoo l-Kewdale. Also with a high risk rating are tanneri es and woolscours with a major concentration in the Coogee area. Figure 2 shows part of the Perth area and indica tes the range of contaminated sites identified .

Diffuse Source Contamination Diffuse so urces of gro undwater contaminati on are either as a result of a widespread landuse practice, such as the use of agricultural nutrients and pesticides , or of a widespread coll ection of discrete yet indeterminate sources, such as septic tanks in an unscwered area. Urbanisation and agricu ltural activity are the main landu ses produ cing diffu se source contamination. Potential sources of gro undwa te r contamination from urban land use comprise: • effluent and cleaning fluid s from septic tanks • domesti c garden fertiliser applica tion • pesticides appl.ied to buildings for termite protection and to ga rd ens for pest control • uncontrolled disposal of household wastes such as paints and solvents • chemical spills from ve hicles usin g residential stree ts • urban stormwater. Currently, 45 % of Perth's household s have septic tanks and the sa nds w hich und erlie Perth do little to prevent septic effluent from leaching into groundwater . An es timated 25 million cubic metres of effluent is discharged annually into Perth 's sa nds , contributing 2,200 tonnes of nitroge n and 440 tonnes of phosphoru s to the groundwater each yea r. It has been es timated that 5,000 tonnes of fertiliser is applied annually to Perth gardens. Of that, an estimated 250 tonnes of nitrogen and 100 tonnes of pho sphorus infiltrate into the groundwater. There is often a time delay in the impa cts occurring in groundwater quality. A study in Gwelup es timated that the full impact of unsewered urban development wo uld be observed 30 years after the start of urban development and that concentrations of nitrate would exceed 10mg/L (as nitroge n) w hich is the current drinking water standard . For agric ultural landu se, clearin g, grazin g, fertili sing and pest control activities affect underlying groundwater quality. The magnitude of impacts ca n be significant with intensive rural uses such as piggeries, tmf farms and horticulture, but is limited fo r broadscale rural uses.

C lea ring of native vegetation for crops and pastures increases groundwate r recharge as well as the sa lini ty and nitrate conce ntration of recharged wa te r. B eneat h dryland grazm g of leguminous (nitrogen-fixi ng) pas tures , significa n t leaching of nitrate from manure and urine in li vestoc k ha s bee n observed. Application of nitrogeno us fertilisers at rates and Figure 2 The range of contaminated sites identified around Perth times that allow leaching of nitrate has affec ted ground- infertility of the sa ndy soils. Nutrients water qu ality o n th e Swan Coastal migrate along the groundwater flow Plain . Irriga ted rural land has the system or surface drains to discharge highest potential for nutrient leaching areas su ch as wetla nd s. Phosphorus due to the high loading rates fro m concentrations may be attenuated by fertiliser applica tion . Nitrate-N levels absorption onto clay minerals , w hilst of 150 mg/L have bee n measured nitrogen conce ntrations may be ben ea th horticulture fertilised with redu ced by denitrifying bacteria in chi cke n manure applied at approxi- anaerobic conditions. However, many mately 1,000 kN/ ha/a on sandy soil. wetlands in the Perth region have ' H owever, this is an extreme loading becom e eutrop hic. · rate. At lower rates of fertiliser applicaStormwater drainage associated with tion s, attenuati o n by ba cteri ologica l developm ent is commonly discharged dcnitrifica tion ca n reduce the impact on into wetlands in Perth, and presents a groundwater qu ality. threa t to groundwa ter and we tland H orticultural land receives multiple quali ty through the addition of nutripesticid e appli ca ti ons eve ry year. A ents, heavy metals, oil and polycyclic stud y from 130 monitoring bore s aromatics. One example is North Lake detected 28 with organochlorin c levels w here an es timated 80% of the exceeding EPA water quali ty criteria. pho sphorus load originated from fertilisers in stormwater runoff. Wetland Water Quality Nutri ent enri chment and algal blooms have the following adverse W etlands act as gro undwater discharge areas. T hu s the water quali ty consequ ences in wetlands: in we tland s is primarily related to the • water weed growth quality of the water in the surrounding • plagu es of non-biting midges • bird and other wildlife deaths from sup erficial aquifer. Contaminants present in the superficial aquifer are botulism and/or algal toxicity • changes in ecosystem structure and carri ed into a wetland through groundwater inflow. T he mo st co mmon produ ctivity problem in wetland water quality is • loss of amenity through odour genernutrient enri chment (e utrophica tion) ation and shoreline fouling. giving ri se to algal blooms and subsequ ent deoxygenation when the bloom Ecosystems Dependent on collapses. Eutrophication results from Groundwater the leaching and migration of nutrients The lowering of the water table as a through the sa nd y profile as a result of result of groundwater abstraction can modified landu se. have significant effects on phreatophytic The sandy soils have extremely low remnant vege tation. The loss of vegetabinding capacity for many substances, tion then results in a faup.a habitat loss. and particul arl y for nitroge n and There has been some observed vegetaphosphorus. Under pre-development tion loss as a result of a combinati on of bu shland co nditi o ns wetlands would groundwater abs traction and poor have received very low nutrient loads. seasonal rains res ulting in a lesser However, post-development urban and recharge of the aquifers. There have agricultural activiti es apply large quanti- been w idespread tree deaths at the ties of nutrients to overcome the natural Gnangara Mound and localised deaths WATER NOVEMBER/DECEMBER 1997

43


ENVIRONMENT at one production bore on the Jandakot Mound . The vegetation deaths on the Gnangara Mound were first noticed in Whiteman Park in early 1991. These were inves tiga ted by the Water Authority and it was found that the vegetation death was primarily by low soil moisture levels as a res ult of a long period of below-average rainfall. T he extent of tree deaths was further exacerbated in the areas of groundwater abstractions because the trees relied on access to saturated groundwater to overcome the lack of unsaturated soil moisture. When gro undwater levels dropped below the root zone , due to abstraction and low recharge, the trees . died becau se they cou ld no longer obtain sufficient soil moisture under high demand conditions. The localised tree deaths observed in Jandakot in early 1994 were within 100 metres of a production bore and within its drawdown cone. Abstraction from that bore has been stopped and production levels are under review.

Managing Wetland Water Levels Changes in wetland wa ter levels have significant environmental consequences because wetland ecosystems are particularly sensitive to this type of change. Following clearing a rise in water table is expected due to increased recharge and from the disposal of stormwater runoff from impermeable surfaces such as roads and roofs. On the other hand, the abstraction of groundwater for water supply can have a drawdown effect resulting in the lowering of water levels and in some cases the complete drying of wetlands. Water level rises du e to urbanisation depend mainly on housing density, bore extraction rates and the type of sewerage and drainage systems adopted. Typical values range from 0.5-2.0 m. The result has been the destruction of wetland vegetation such as paperbarks and rushes and the introductio n of exo tic weeds. Many wetlands are now deeper and contain water for a longer period than in their natural state before urbanisation. Dead trees in wetlands such as Blue Gum Swamp and Lake Claremont are evidence that these now permanent swamps previously dried or had lower wa ter levels. For Thomson's Lake, artificial drainage is being implemented to manage levels rising due to urbanisation in the catchment. In the Jandakot Groundwater Scheme Stage 2, it was estimated that the area of we tland impact by the abstraction proposal would be about 23 ha , while the area of wetland lost would be about 17 ha. Specific mitigation measures to co unter this were put 44

WATER NOVEMBER/ DECEMBER 1997

forward for Twin Bartram Swamp, Bibra Lake, Thomson's Lake, Branch Street Swamp, Banganup Lake, Yangebup Lake and Kogob up Lakes.

Environmental Protection Mechanisms The Environmental Protection Act defines three main mechanisms for the implementation of environmental protection that can be appli ed to groundwater: • Environmental Protection Policies (Part III of the Act) • Environmental Impact Assessment (Part IV of the Act) • Control of Pollution (Part V of the Act) . For the past two years, the DEP has had the State responsibility for regulating waste management for which it reli es on provisions of both the Environmental Protection Act and the Health Act.

Underlying Principles The DEP strategy is based on the underlying principles of sustainable development and polluti on prevention. The co ncept of sustainable development includes the maintenance of biodiversity. This implies the maintenance of phreatophytic vegetation and wetland ecosystems dependent on groundwater. It includes the maintenance of renewable resources, which implies mainta111111g groundwate r quantity. It also includes the maintenance of bi ogeochemica l processes, wh ich is of particular relevance to linking environmental and groundwater protection in sustaining the natural hydrologic variations for we tlands which is needed to maintain fri nging vegetation. Polluti on prevention impli es maintaining water quality for potential uses and the management of environmental risk. The nature of the overlying landuse is one of the most significant components in managing the risk of groundwater contamination . Sustainable development also implies certain management principles including the precautionary principle, which states that w here there are threats of serio us or irreversible enviro nmental damage, lack of full scientific certainty should not be used as a reason for postponing measures to prevent environmental damage . Adaptive environmental management is another: where there is uncertainty of o utcome, monitoring is required and management action needs to be taken to correct any adverse consequences. Together these imply the need for some conservatism 111 providing environmental protection in relation to groundwater. Where significant uncer-

tainty exists, decisions should not lead to irreversible consequences. Furthermore, monitoring is required of expected outcomes so that contingency plans can be implemented if outcomes vary from what was predicted.

Policies E nvironmental Protection Policies (EPPs) are formulated under Part III of the Environmental Protection Act and are legally binding documents passed by the State Parliamen · They are form ulated by the Environmental Protection Authority for the Minister for the Environment. An EPP has been finalised for the Crown Land area (mainly State Forest) of the Gnangara Mound , and draft EPPs have been formulated for some of the private land at Gnangara and the area of Jandakot Mound set aside for public water supply. Wetlands on the Swan Coastal Plain are also covered by an EPP which provides statuto ry protection for many wetlands with respect to pollution, filling, draining and mining. A successful pro sec ution under the provisions of the EPP has just been completed for placing fill in a protected lake. The Selec t Committee of the Legislative Assembly established to appraise the impact of landuse 011 the environmental resources in the declared gro undwater mounds 111 Perth expressed concerns that there were a number of regulatory instruments in place or proposed to be implemented to protect groundwater mounds and that there were some inconsistencies between them. The committee recomm ended that a w hole-of-government response be developed to coordinate government action. The EPA responded to this by agreeing to initiate a Statewide Environmental Protection Policy for the protection of groundwater which would complement regulatory instrum ents of the other relevant agencies (W estern Au stralia Planning Commission and the Water and Rivers Commission). This EPP would propose broad obj ec tives for groundwater protection which could apply throughout the State where there were important groundwater resources. Separate attachments would be added to deal with specific areas. The EPP would deal with both water quality and water quantity issues and would cover protection of groundwater for ,both human use and ecosystem maintenance. Rather than individual EPPs for areas such as Gnangara and Jandakot, it is envisaged that the State Groundwater EPP will be an umbrella policy for the whole State. Individual areas such as Gnangara and Jandakot will be covered


ENVIRONMENT Swan River. With regard t~ we tland water levels, the 17 .6m - maximum water levet +(1m - 0.3m) = 0.7m proponents were Environmental Impact required to esta16.9m {lowest melaleuca growth) blish water level Assessment 16.6mAH0 criteria based on Environmental impa ct assessment +O.Sm to prevent -1 .0m historic data and downsk>pe movement seasonal has been used to protect groundwater range 15.8m (lowest point cf by placing conditions on the abstraction further groundgrowth) of groundwater to protect wetlands and water modelling by placing conditi ons on potentially to ensure the maintenance of pollu ting activities. Figure 3 Water leve l criteria established for Lake Joonda lup Environmental impact assessment in rmrumum, maxiWestern Australia is carried out under mum and optiPart IV of the Environmental mum water levels and seasonal patterns the State Groundwater EPP. Another recent development is the Protection Act through the in the Lexia wetlands and other conserformal environmental assessment of vation areas. An example of the water Environmental Protection Authority (EPA). The EPA is a five-person , part- level criteria establish ed for Lake planning schemes and scheme amendments. Changes to the planning and time board appoin ted by the State J oondalup is shown in Figure 3. environmental legislation provide for One recent development has been government to provide expert advice on a range of environmental issues. Its role preparation of policies for assessment in the integration of the two statutory in environmental impact assessment is advance of proposals, particularly w here processes: planning sc heme approval that it advises the Minister fo r the there were concerns for cumulative and environmental impact assessment. Environment on the environmental impacts. One example is the protection Other changes to planning legislation fac tors that are relevant to a proposal, of Lake C lifton from rural, residential also allow regional planning schemes w hether the project should proceed, and horticultural development within outside the Perth metropolitan region to be prepared. Regional planning and recommends appropriate environ- its groundwater-fed catchment. schemes for the two fastest growing Lake C lifton is one of the most mental conditions w hich should apply to approved proj ects. T he Minister for signifi cant we tlands in Western areas outside of Perth-the Peel Region the Environment, and not the EPA, Australia and is located about 100 km and Bunbury-are being prepared. makes the fina l decision. The DEP south of Perth. It is internationally Environmental instructions of the issues provides technical services to the EPA important as a waterbird habitat and to be addressed by these schemes are and administers the assessment process because it contains the largest known being developed. 'This includes the example of living stromatolites, linking of environmental and groundon behalf of the EPA and the Minister. In 1986 the EPA assessed the (then) properly called thrombolites, in a lake water protection at this most crucial 111 the southern stage of landuse allocation by the Water Authority of Western Australia's environment regional planning scheme. proposal to abstract groundwater for hemisphere . Much of the water which flows into public water supply purposes from the G nangara Mound. T he relationship the lake comes from a small freshwater Pollution Control Part V of the Environmental be tween we tlan d hydrology and aquifer. This water is particularly abstraction was the main environmental important as it supplies carbonate and Protection Act provides powers to iss ue in that assessment. T he EPA bicarbonate ions necessary for contin- control pollution and for the managerecommended approval of the proposal ued thrombolite growth . These throm- ment and control of all wastes subj ect to the hydrology of important bolites are particularly sensitive to the discharged into or placed in the wetlands being maintained. The criteria amount of freshwater entering the lake environment. Prescribed premises are defined as premises which have a governing the extraction of ground- and its water quality. Much of the land in the groundwater known potential to pollu te. Before water from the Gnangara Mound were can commence, a recently reviewed and a combination of catchment is privately owned. The EPA construc tion water level and species diversity criteria has developed specific environmental prescribed premises requires a works have been defined to limit extraction cri teria to limit the environmental approval, and operation of a prescribed rates to environmenta lly acceptable effects on groundwater quantity and premises requires a pollution control quality due to changes in landuse on licence. In cases where the CEO is satislevels. The EPA also assessed the Water private land in Lake C lifton's ca tch- fied that the occupier of a premise is not Authority's proposal to abstract ground- ment. These criteria have been complying with emission standards or en dorsed by the State planning waste management requirements a wa ter from the Jandakot Mound. Wes tern Australian pollution aba tement notice may be E nvironm ental impact assessment agency-the has been used to control potentially Planning Commission (WAPC)-and served. These are registered against the polluting developments on b oth have been included in an imminent title of the land until revoked by the mounds including service stations, golf Coastal and Lakelands Planning CEO. The provisions of Part V provide courses, horticulture and housing Strategy w hich has been prepared by the W APC to guide development in the some ability to manage contaminated developments. For example, the requirement for a area. With the j oint agreement of the sites. For example, directions under drainage and n utrient management plan EPA and WAPC, development in the Section 73 of the Act have been used was impo sed on the Ellenbrook urban catchment of Lake Clifton can now be recently to require the cleanup of a spill development proposal, which is located controlled in a manner which should of agricultural chemicals from a storage next to and partly on the Gnangara protect Lake Clifton in the long term. It container at Wongan Hills. However, Mound , to counterac t the potential is expected that the EPA's non-binding the Ac t does not specifically address the impact on the mound , the Lexia policies will be translated into statutory problem of managing land after it has wetlands, remnant vegetation and the planning schemes or regulations under become contam..inated and issues such as by regulations under the EPP. Complementa ry planning and water resource regulations will also be promulgated.

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ENVIRONMENT liability and the definition of pollution are unclear. Furthermore, in Perth, the problem of contaminated groundwa ter as a result of land contamination adds a complica tion that has not bee n adequately addressed elsewhere in Au stralia. DEP has released a position paper o n propo sals for the management of contaminated sites. The proposals are based on the benefi cial use concept , wi th different areas of gro undwater being protected to a different level based on th e beneficial u se of t he gro undwater in q uestion . Investigation levels or 'levels of concern' that are used to trigger investigations will be developed based on existing ANZECC cri te. ria , and the polluter pays principle will be enforced wherever possible. A database of contaminated groundwater plumes will be established. This will provide improved access to information on contaminated groundwater and regulatory agencies will then be in a better position to iden tify pote ntial issues of concern and monitor the transport of contaminants and changes in groundwater quality. Importantly, the D EP recognises two aspects of the management of con taminated groundwater. The first is that cleanup criteria, as opposed to investigation criteria, will apply at the point where the gro undwater is having its effect, as opposed to withi n the aq ui fe r. T hus, cleanup criteria will be applied at a wellhead, for example, and then modelled back towards the contaminated area, to estimate the impact of the contaminated groundwater. T h e second aspect that the DEP recognises is that w hen all other approaches have been examined and there is no viable alternative, restricting access to an aquifer is the only available way of managing contaminated groundwater. This approach, which is a 'last resort ,' would only be acceptable where affected groundwater users are compensated and where an acceptable monitoring program over the term of contamination is proposed. For this proposal to be effective , the DEP m ust be empowered to declare areas where groundwater abstrac tion cannot take place or its beneficial uses restricted. Finally the question of liability for contaminated groundwater is perhaps the most prob lematic, give n the movement of groundwater away from the source of contamination . T he DEP believes that the polluter pays principle should apply for co ntaminated groundwa ter-the party w hi ch ca u sed the damage or controls the source of th e groundwater contamination should pay for investigation and/or cleanup . For sites w here groundwa ter is contaminated from a source offsite, cleanup of 46

WATER NOVEMBER/ DECEMBER 1997

contaminated gro undwater wou ld not be the requirement of the site owner or occupi er. Where the polluter cannot be found, the DEP will be able to order an owner or occupier to investigate contaminated gro undwater to determine if th eir site is the source of contamination. If that investigation determines that the source of contamination is offsite, then that is the limi t of th e ob li ga tions of that owner or occupier. The government will then be responsible for ensuring that any further investiga tion, n1011itoring and if necessa ry cleanup of the contaminated aquifer takes place.

Waste Management In view ofW A's reliance on groundwater for water supply purposes , the DEP has focused particular attention on the protec tion of ground water when develo ping policies relevant to the management of landfill s. The Department's policies are set o ut in two policy papers: • C riteria for Landfill Management • Wa ste Acce ptance Criteria for Landfills in W es tern Australia. T hese policy documents desc ribe a classifi ca tion system for landfill s from C lass I (Inert Landfill s) through to Class V (Intractable Landfills) and set broad criteri a for design and opera ti o nal standards for each class of landfill. In addition waste acceptance criteria are se t w hich define w hich types of waste are suitabl e for each class of landfill. More detailed control is achieved by issuing approvals under the Health Act of WA and requiring all landfill sites to operate in accordance with Environmental M anagement Plan s. Under this sys te m , wastes w hi ch are n10re hazardous mu st be directed to landfill s of higher sta ndard where they can be handled in a manner w hi ch ensures that impacts are co ntained wit hin th e environment of the landfill . This ap proach means that the costs of disposal accord with the level of threat associa ted with a parti cular waste type. This is important as hi gh disposal costs can provide significant incentives for ill egal or improper management of wastes. The Criteria for La ndfill Management also set a series of compliance dates for either upgrading or closing landfills if they fai led to meet required standards. As a result of these poli cies, three major unlined landfills which operated on the sensitive coastal sa nd plan have now closed, a furth er landfill will close within 12 months, and within 2-3 years, the tvvo remaining unlined facilities will either close or move to a fully-lined opera tion . T his has been an outstanding outcome for protection of groundwa ter quality.

T he recent repo rt of the Selec t Co mmittee on R ecyling and Waste Management paid particular attention to th e relationship between landfills and groundwater protection on the Swan Coastal Plain. Recommendation No. 1 of the report was that ' No new landfill sites should be establi shed on the coastal sa nd plain beca use of their potential to pollute gro undwater.' T his is consistent with work being undertaken by the DEP in waste management. Approval (thro ugh the environme ntal assessment process) has been granted to one new landfill in the metropolitan area w hich has been sited off the coastal plain. The Government recently decided to license all waste management facilities, incl udi ng landfills under the Environmental Protection Act. This decision will provide a clearer more accountable system for regulating the opera tion of landfills and will facilitate the implementation of the policies outlined above . Some 300 landfill facilities operating around the State have bee n li ce nse d at 30 Ju ne 1997. Licensing of all landfill s wi ll incl ude provisions fo r groundwater protection and 111.onitoring. In formation on landfills and contamin ated sites held by the DEP will be integrated through 1inked geographic information systems with groundwa ter information held by the Water and Rivers Commission.

Concluslon Although there is a suite of mechanisms in place to link environmental and groundwater protection, the DEP is putting in additi onal measures to improve its environmental management ca pabili ty in this area. In addition to the curren t e nviro nmental protec ti on poli cies, environmental assessmen t procedures , polluti o n controls and waste management provisions, the foll owing new developments are occurring: • a statewide gro undwater environmental protection policy with regulations for specifi c areas • establishin g policies fo r assessment for issues such as develop ments in ca tchments • forma l assessment of planning schemes • additional potential control provisions for contaminated sites • no landfills on the Swan Coastal Plain • the licensing of waste ,management facilities.

Author Dr Bryan Jenkins is C hief Executive Officer of the Western Au stralian D epartment of E nvironmental Protection.

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Water Journal November - December 1997  

Water Journal November - December 1997