Page 1


water

ISSN 0310-0367

Volume 17, No. 1, February 1990

Official Journal AU STRALIAN WATER AND WASTEWATER ASSOCIATION

CONTENTS My Point of View ......... .. .. . . . ... . .. . Association News

3

President's Report . . . . . ..... . ...... . . . It Seems to Me ... .. . . ..... . .. ... .. ... .... . .

6 6 12 12

IAWPRC News .. . ....... . .... . ....... .. . Industry News . . .. . . . . . . . . . . . .. . . .. .. . . . Seminar Reports Victorian Water Quality Seminar . . . . . . . . . . . . . . Sewage Sludge Treatment . . . . . . . . . . . . . . . . .

Book Review ........ . ...... . ...... . . .. . Conference Calendar ................ . . . . Technical Note: Why is some of our water so coloured? .... ... ... . .... . .. . .. .. . .. .

36 36

Plant, Products and Equipment

40

38

13 15

Features A Dynamic Water Resource Management Strategy for South Australia G. F. McIntosh . . . . . . . . . . . . . . . . . . . . . . . . . . Tracing Toxic Di scharges by Biofilm Analysis: Survey ·of Adelaide Sewers D. P Oliver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asset Replacement: Can We Get It Right? R. D. S. Clark . . . . . . . . . . . . . . . . . . . . . . . . . . Ion Chromatography - A Technique fo r the Analysis of Inorganic Ions in Environmental Samples T. A. Bowser and 8. J. Wildman . . . . . . . . . . . . . . Effect of Changing from Chlorination to Chloramination on Microbiological Quality D. A. Cuncliffe, P E. Christy, 8. Robinson and R. P Walters . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mechanical Mixers: An Alternative Destratification Technique. Myponga Reservoir, South Australia P J. Suter and G. Kilmore ........

FEDERAL SECRETARIAT P.O. Box 460, Chatswood NSW 2057 Facsimile (02) 410 9652 Telephone (02) 413 1288 Ottice Manager - Margaret Bates

BRANCH SECRETARIES Canberra, A.C.T. M. Sharpin, G .H. & D., P.O. Box 780, Canberra 2601 (062) 498 522

FEDERAL PRESIDENT Timothy Smyth, GHD Group Director, Telephone (02) 690 7070

EXECUTIVE DIRECTOR Peter Hughes, Telephone (02) 41 0 9654

FEDERAL SECRETARY Greg Cawston, Telephone (042) 29 0236

New South Wales Mr David Hope, P.O. Box 460, Chatswood 2057 (02) 269 5212

Victoria J. Park, Water Training Centre, P.O. Box 409, Werribee, 3030. (03) 741 5844

FEDERAL TREASURER John Molloy Telephone (03) 615 5991

Queensland D. Mackay, P.O. Box 412, West End 41 01. (07) 840 4844

16 19 22 1

25

28

OUR COVER Happy Valley Water Filtration Plant showing Stage 1 (completed November 1989) and Stage 2 proceeding with a completion date of June 1991 anticipated.

32

South Aust ralia R. Townsend , State Water Laboratories, E. & W.S. Private Mail Bag , Salisbury, 5108. (08) 259 0244 Western Australia A. Gale, Bi'nnie & Part P/L, P.O. Box 709, Garden Olfice Park, Herdsman, 6017 (09) 242 4677

Tasmania A. B. Denne, P.O. Box 78A, Hobart 7001 (002) 30 5562 Northern Te rritory D. Hardiment, GPO Box 250 Darwin, N.T. 0801 (089) 41 0 144

EDITORIAL CORRESPONDENCE E. A. Swinton,

4 Pleasant View Crea., Glen Waverley 3150 Office (03) 560 4752 Home (03) 560 9306

Fex C/· 543 6613 (Advise per phone)

ADVERTISING Ann Sykes, Applta, 191 Royal Parade, Parkville 3052 (03) 347 2377 Fex (03) 348 1206

PRODUCTION EDITOR J. Grainger, Applta, 191 Royal Parade, Parkville 3052 (03) 347 2377 Fax (03) 348 1206

WATER February, 1990


A Dynamic Water Resource Management Strategy for South Australia by G. F. McINIDSH ABSTRACT The South Australian Government has adopted a carefully considered strategy to guide water resource planning and management activities and priorities into the longer term. The Strategy encompasses the concepts of community consultation, integration of land and water resource management, establishment of a business-like approach to water management, taking account of the social and environmental effects of water use and evaluation of monitoring and research needs. To be successful the Strategy must be implemented in a flexible manner in order to accommodate regional and / or local circumstances and be periodically reviewed to retain socio/ political relevance. Community involvement in this process will be essential.

INTRODUCTION The development of South Australia's water resources has, from an early stage, been a responsibility of the State Government exercised through the Engineering and Water Supply Department. This has been paralleled by an involvement in railway and road construction and the survey and allocation of land. However, in the development of the State's water resources many climatic constraints have had to be overcome. Locally available water resources were frequently found to be inadequate to service any but relatively small-scale development. As a result, the supply of water by pipeline from distant sources gradually became a way of life in many parts of the State. This form of water resource development is evident in the extensive pipeline systems constructed to convey River Murray water to metropolitan Adelaide and communities from the Mid-North to the South-East of the State. Extensive pipelines independent of the River Murray were also constructed on Eyre Peninsula (Figure 1). However, in some cases development has caused deterioration of the quality of available water resources and increasing water demands in some areas have created competition for limited resources. , E3

0 km

E3

E3

E3

E-3

50

'

100

Pipe lin es

:;:::t!:,_

Ground wat er Basi n

~-

0

Reservo ir

Gordon McIntosh is the Supervising Planning Engineer of the Strategic Planning Section, Engineering and Water Supply Department, Adelaide, South Australia. Previously he has worked with various organisations involved in water resources including nine years with the Commonwealth Bureau of Meteorology in Brisbane engaged in the design and operation of flood forecasting systems. G.F. McIntosh

These factors, together with economic constraints and community expectations for greater consideration to be given to environmental and other factors, have combined to usher in a new era in water resources management in recent years. Great emphasis is now being placed upon careful management of the State's water resources to ensure that the surface and groundwater resources are used for the greatest benefit to the community. The introduction of the Water Resources Act (1976) provided the legislative power to manage the water resources of the State, including their development, use, conservation, and quality. Provisions were made in this Act for involving the public in the planning and management process. The Act created a Water Resources Council to advise the Minister on the assessment, management and protection of the State's ',',;ater resources. Water Resources Advisory Committees were established for each region and resource proclaimed for specific groundwater or surface water management. Wide-ranging powers were afforded to allow for the consideration of all matters relateq to water resources, and an Appeal Tribunal was created to enable appeals to be heard against administrative decisions under the Act. Three watercourses and twelve groundwater regions have been proclaimed.

DEVEWPMENT OF A STRATEGY A conscious decision was taken in 1982 for the development of a Strategy which should incorporate: • a regional approach to issue identification and alternative means of resolution. Water resource management reviews were progressively undertaken for each of the 5 operational country regions of the Engineering and Water Supply Department over a 4 year period. (EWSD 83 / 38, 1984; 84/ 3, 1985; 85/2, 1986; 87 / 4, 1987 and 86/ 32, 1988); • a statewide perspective of water availability and use and historical development of water resource management. (EWSD 86/ 34, 1987; and 86/ 35, 1987); • acceptance of the reality that data and other information will be incomplete but must be accepted as the best available.

Great Australian Bfght

Spencer

Gull

ULEY-WANILLA ULEY SOUTH

LINCOLN 'C'

LINCOLN 'B' Fig. 1 -

Reticulated Water Supply System -

16 WATER February, 1990

Ey~e Pensinsula

• a maximum time period of 30 years for projections into the future; • involvement of the community through input from relevant water resource advisory committees and local authorities (Eyre Peninsula) in preparing regional reviews and the public at large in providing comment on resultant proposals before being given a statewide perspective and incorporated into the Strategy; • current public and private perceptions (but be capable of absorbing changes in either or both in future); • provision for sensitive implementation which recognises that there are different means to an end and that these vary throughout the State. It soon became apparent that current water use on a broad statewide basis only accounts for about 20% of the water available


on a sustainable basis. This is graphically presented in relation to major water resources in Figure 2. However, in general, the resources already developed represent those of best quality and greatest eas~ of harvesting although some are being subjected to pollution pressures from land use and waste disposal practices. The future development potential of the remaining water is dependent on location, quality and degree of competing environmental use. A review of 21 alternative water development options for South Australia was carried out (EWSD 89/4, 1989). 0

denotes 10.0 GL/year availability

major resource use

Ill

evaporation

SURFACE WATER El LAKE TORRENS

·a

MT LOFTY RANGES

GROUNDWATER EUCLA AND OFFICER BASINS

GREAT ARTESIAN BASIN

II

EYRE PENINSULA

MURRAY BASIN

PIRIE TORRENS BASIN

YOR.KE PENINSULA

in managing assets with a $9 billion replacement value; 4. increased account to be taken of the social and environmental impacts of water resource management to promote the needs of the natural environment and of social justice in decision making processes; 5. improved monitoring of, and research into, factors related to water resource management to facilitate future timely reactions to emerging issues. Proposals To implement the Strategy, the following broad actions are proposed , subject to extensive community consultation: 1. Increase the availability of water resources management information to the community; encourage water resources advisory committees to be the focus of community consultation in their areas; and establish closer contacts with interested groups throughout South Australia. 2. Manage interdependent ground and surface water resources as single units taking into account management objectives of other natural resources and a level of water demand which can be sustained in the long term. 3. Extend arrangements to enable the transfer of authorised irrigation and industrial licences in proclaimed regions subject to Government-approved management plans and transfer conditions, thereby allowing market forces and commercial decisions by users to directly influence the attainment of the best use of the water; and extend a publicly-reasoned pricing structure which reflects the value of water and which provides increased incentives for efficient water use and waste disposal. 4. In conjunction with other government agencies, determine the relationship between water resources management and the social and natural environment and develop techniques for their meaningful integration into the decision-making process. 5. In conjunction with other government agencies establish and maintain a comprehensive water resources related information monitoring network and ensure regular review of information in order to determine trends and actions hecessary to address implications.

OTWAY BASIN

I

ST VINCENT BASIN

Fig. 2 -

ii

MT LOFTY / FLINDERS RANGES

Utilisation of major water resources.

In essence, it was confirmed that for the foreseeable future, South Australians generally will continue to have access to reliable water supplies but careful management will be required now and in the longer term if this situation is to be maintained and future development potential maximised.

THE STRATEGY A strategy to provide direction for future water management in South Australia was released by the Minister of Water Resources, the Hon Ms Susan Lenehan, on Wednesday 25 October 1989 (EWSD 83/86, 1989) entitled "Water South Australia - Managing the Resource in the Next Century". The fundamental principles underlying this endeavour revolve around community involvement, open government and deregulation. An outline of the issues, proposals and priorities follow. The issues There is a need for: 1. increased communication with the community on matters related to water resource management in order to establish the needs of the community and to ensure its timely involvement in the resolution of issues;

2. integrated land and water management to ensure that due consideration is given to the sustainability of all natural resources; 3. water used for urban, industrial, irrigation, and rural applications to be regarded as a commodity subject to commercial market forces. This will introduce a business-like approach to the allocation and use of water, and the control of pollution. It will also force a recognition of the substantial effort and cost involved

Priorities 1 Priorities for future actions will be determined by the importance of the resource, the consequences of failure to take action and the importance of each action for the resource. Each action is interdependent and should not be viewed in isolation. However, within each group of actions there is a hierarchy with some actions dependent on the completion of others. The most important resources requiring management attention in South Australia are the River Murray, the Mount Lofty Ranges streams, the Otway Basin groundwater and the Great Artesian Basin. In addition a host of smaller resources are over-used or reaching sustainable yield. Other critical issues are the environmental impacts of wastewater management, particularly the effects of disposal of effluents on receiving waters, the management of toxic and trade wastes, and importantly, the management, operation and renewal of the massive assets of the Department. In fact, many specific actions either emanating from investigations contributing to the Strategy or which had attained their own independent momentum in recent times, are currently being undertaken as a matter of priority. Such current or recent initiatives include incorporating the powers to control diffuse sources of pollution within a revision of the Water Resources Act, investigations into the potential for minimising the current harmful and wasteful effects of urban stormwater disposal, (EWSD 85/ 16, 1989) and the development of a strategy for the treatment and disposal of sewage to the marine environment (EWSD August 1989). Having established the initial momentum, identified the issues, formulated corresponding proposals, and taken public comment into account, the Department will be in a strong position to manage the planning, development and utilisation of the State's water resources in the next decade and into the 21st century.

MAINTAINING THE MOMENTUM It is essential that the strong position now attained not be allowed to diminish and that the Strategy be promoted as a catalyst for WATER February, 1990

17


maintaining momentum. This will be achieved initially by undertaking workshops involving the community at large, water resources advisory committees (Figure 3) and the governing councils of organisations which have a stake in water resource management ie with interests in irrigation, environmental protection, rural water supplies, state development, recreation and sport. The specific function of these workshops will be to establish the Strategy's credibility, gauge reactions, determine relative priorities and lay the ground rules for future involvement during the implementation and review phases. This wider involvement will be particularly useful in the assessment of value judgements (social impacts) relative to the particular requirements of local areas.

This achievement is but the first stage in a continuing cyclic process in which the Strategy must be mai'k:eted, implemented, regularly reviewed and updated as a dynamic working interface (perspective, relevance ahd priority) between the community, the Water Resources Council, the Engineering and Water Supply Department and the Government. The success of this endeavour will depend on a wide acceptance of the new directions embodied in the strategy and the goodwill of both the public and private sectors in working together to address the issues. Within days of the public release of Water South Australia: Managing the Resource into the Next Century (EWS 83/36, 1989), there appeared a number of articles in the local press which clearly reflected a deeper insight concerning the management of South Australia's water resources. One article addressed the potentially unpalatable aspect of water pricing but placed this neatly into perspective by discussing how the present system could be changed, the enormous cost of asset replacement and the potential benefits of water conservation. A concluding paragraph stating, 'no wonder the department wants us to conserve water' has provided the community with an independent and well reasoned background to a series of related issues which had become confused in recent times. Such articles can only help educate the community on the wider issues involved and elevate the level of debate and eventual participation.

ACKNOWLEDGEMENTS PROCLAIMEO REGION/ WATERCOURSE

WATER RESOURCE ADVISORY COMMITTEE

TATIARA

River Murr ay

Ri ver Murray

NARACOORTE

Northern Adelalde Pla i ns Li tt le Para River Boli var Outfall Channel

Northern Adelai de Plains

RANGES

Angas - Bremer

Angas - Bremer

Padthaway Tat1ara

Upper Soun, Eas t

The author wishes to thank Messrs A. Ockenden and B. Van der Wei who both assisted in large measure in the formulation of the Strategy and associated documents and Messrs P.A.Norman, Director Technical Services and D.J.Alexander, Chief Executive Officer Engineering and Water Supply Department for their direct involvement and support during the approval phase.

PADTHAWAT

COMAUM-CAROLINE

REFERENCES

Naracoorte Ranges Mallee

Mallee

Noor a Cur di murk a

Arid Area s

Comaum - Ca rollne

l ower South East

Southern Basins Musgra ve

Eyr e Region

Barossa

Nort h Para

Fig. 3 -

Proclaimed Region Denotes Proc laimed Watercourse

0km

100

c;:s;;J

* 200

Proclaimed Watercourses and Regions

Subsequently it will be necessary to: • continue to educate the general community with background information on general and specific issues (newspaper, newsletter, brochure, radio); • as the situation arise, evaluate options and formulate management proposals in conjunction with local representative groups; • debate the options and proposals in public; • refine the proposals, where appropriate for presentation to government along with an estimate of cost and benefits and an assessment of both environmental and social impact. In circumstances where mature management plans have been developed and are in operation, it is envisaged that the administration of these plans could gradually become the responsibility of local organisations operating within guidelines approved by the Government and with the assistance of technical advice as required. Within the Engineering and Water Supply Department itself it is essential that the Strategy be embraced as a reference against which all water resource planning and management activities are justified and thus provide for a commonality of purpose and a consistency of endeavour. The Strategy provides a basis for evaluating progress of management initiatives and for incorporating changes. Such changes, resulting from five yearly (maximum) reviews involving community consultation will ensure the continuity of a process with updated relevance to the current and evolving socio/political climate.

CONCLUSIONS I For the first time, a strategy has now been developed to guide the management of ground and surface waters of the State in order to ensure that they are used for the greatest benefit to the community. 18

WATER February, 1990

The following reports of the S.A. Engineering and Water Supply Department are referred to in the paper. EWSD 83/ 86 (1989). Water South Australia - Managing the Resource into the Next Century. EWSD 89/ 4 (1989). South Australia Water Futures - 21 Options for the 21st Century. EWSD 89/ 16 (1989). Urban Stormwater, a Resf'urce for Adelaide. EWSD August (1989). Strategy for Mitigation ofMarine Pollution in South Australia. EWSD 86/ 52 (1988). Northern Region Water Resources Management Review (Unpublished). EWSD 86/ 34 (1987). Water Resources Development 1836-1986. EWSD 86/ 35 (1987). Water Resources Inventory. EWSD 87/ 4 (1987). River Murray Water Resources Management Review. EWSD 85/2 (1986) . Metropolitan Region Water Resources Management Review (Unpublished). EWSD 84/ 3 (1985). South East Region Water Resources Management Review. EWSD 83 / 38 (1984) . Eyre_Region Water Resources Management Review.

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Tracing Toxic Discharges by Biofilm Analysis: Survey of Adelaide Sewers by D. P. OLIVER ABSTRACT Metals are discharged in wastewater from industries such as electroplaters, galvanisers and leather tanners. This is of major concern because of the inability of biological sewage treatment plants to treat surges of heavy metals, which in some cases has resulted in failure of the treatment plant. The current method of identifying industries that discharge metalladen sewage is time-consuming and often unreliable. This study sought to determine the effectiveness of sewer biofilm (slime) analysis as an alternative technique. The preliminary study reported in this paper showed large differences in metal concentration in sewer biofilm depending on the location of the sewer and the . wastewater discharged into the sewer. The kinetics of metal uptake by biofilm are currently being investigated in the laboratory.

INTRODUCTION The discharge of metal-laden effluent is cause for concern because of the toxicity of heavy metals to man and to the environment. Metallic contaminants in sewage are not normally amenable to biological treatment (Metzner, 1977) and overloading biological treatment plants with heavy metals has been observed to have toxic effects on the bacteria (Jarrel et al., 1987; Lester, 1983). This may result in ineffective treatment of normal sanitary wastes. The metals in the study may become concentrated, rendering the sludge unsuitable for agricultural purposes (Metzner, 1977). Protection of sewage treatment plants and of the aquatic environment has prompted most states and territories in Australia to legislate for permissible limits of metals in effluents. However, enforcing such legislation is not easy. Identifying industries which discharge effluent containing metals above the permissible standards currently depends on the collection of grab samples of sewage. Wastewater streams are not constant in quantity nor quality over time, and are poorly represented by single grab samples. In order to detect the point source(s) of contamination it is necessary to monitor continuously. However, conventional monitoring systems, such as sampling at hourly intervals over a twenty-four hour period, are both time-consuming and expensive. Consequently, an alternative technique was sought for identifying point sources of illegal discharges. Sludge polymers have been shown to exhibit an affinity for metals (Rudd et al., 1984) and studies in Germany utilised sewer biofilm (slime) analysis as a potential technique for tracing toxic discharges (Gutekunst and Hahn, 1985). These early findings were investigated further in this survey of metal concentration in sewer slime from different sites in the Adelaide metropolitan area.

BIOFILM PROPERTIES Marshall (1976) described a biofilm as an assemblage of bacterial cells that is both enclosed by and attached to a wetted surface by means of an extracellular, fibrous, polysaccharide-containing matrix. The matrix is composed primarily of polysaccharides, proteins, RNA and DNA (Pavioni, 1972) and the functions of most extracellular polysaccharides are related to the two properties common to the majority of polysaccharides: • they are hydrophilic (Wilkinson, 1958); • the majority of polymer surfaces consist mainly of anionic functional groups (Eighmy et al., 1983; Pavioni, 1972).

It has been suggested that extracellular polysaccharides provide the organisms within the biofilm protection against phagocytosis, amoeba attack, bacteriophage and desiccation. They may also assist in nutrient and ion uptake and aid in dispersal.

Danielle Oliver is a graduate from the University of Tasmania (B Agr Sci (Hons), 1986). She was a Scientific Officer with the Australian Centre for Water Treatment and Water Quality Research, and is currently employed as an Experimental Scientist at the CSIRO Division of Soils, Adelaide.

D. Oliver

Bacterial polymers have been found to exhibit anion-like adsorption behaviour (Pavioni, 1972). A review by Brown and Lester (1979) stated that activated sludge floes and extracellular polymers were able to remove iron, copper, chromium and zinc most efficiently from wastewater while nickel, manganese, cadmium and magnesium were removed less efficiently. Observations that the extracellular slime produced by organisms greatly improved the metal adsorption capacity of sludge organisms (Brown and Lester, 1982; Rudd et al., 1984) led to the development of this investigation.

SITE SELECTION Sampling sites were chosen to represent tht; following categories. Residential: Sewers which serviced no heavy industry. These sites served as controls and allowed the establishment of base levels for metal concentration in slime.

Periodic Dischargers: Sewers adjacent to industries which periodically discharged metal-laden effluent, either to industrial processes or due to irregularly serviced pre-treatment plants. Continuous Dischargers: Sewers adjacent to industries suspected of continuously discharging metal-laden effluent. Originally two residential sites, two periodic and two continuous dischargers were chosen but sampling at one site in each of the latter two categories had to be discontinued due to insufficient slime at these sites. The two residential sampling sites were in the Adelaide suburbs of Blair Athol and Burnside.

PROCEDURES Metal Contamination

Metal contamination from glassware and implements is a hazard for heavy metal analysis. For this reason no metal instruments were used and great care was taken in glassware preparation. All samples (raw, wet and dried) were handled using a plastic kitchen scraper and collected into polystyrene specimen containers. In the laboratory, samples were transfered to 100 mL beakers using the plastic handle of a spatula or a plastic spoon. All glassware used for metal analyses was soaked in Deconex 24(R), a phosphate-free laboratory cleaner, for at least thirty minutes. After soaking, the glassware was washed in the dishwasher using Deconex 25 Organacid (R), a phosphate-free neutralisation agent. Following this, all glassware was rinsed once with doubledistilled water (DDW) and then allowed to soak overnight in DDW before draining. Slime Sampling

Slime samples were collected fortnightly over a six week period between November and December 1988. The sewers were entered following safety requirements for entering a confined sewerage WATER February, 1990

19


system (EWSD, 1978) and to facilitate sampling, the flow of sewage was temporarily stopped using a motorised plunger. Five slime samples (approximately S-10 g) per site were collected into individual polystyrene containers and stored at 4 ° C until required. Analytical Methods Wet samples were homogenised using an Analite (R) homogeniser with a Teflon grinding attachment. A subsample (approx. 2-4g) of each slime sample was transferred to a beaker from the collection containers, oven-dried at 105 °C overnight and the dry weight calculated. Following the comparison of the two drying techniques oven-drying was preferred to freeze-drying for the following reasons:

• Significant metal loss had been reported from freeze-dried biological material (Harris et al., 1983). • It was more practical because of the large number of samples which could be processed in the oven <:ompared with the freeze-dryer. • The technique would have wider use as ovens are standard equipment in most laboratories. · After oven-drying 4 mL cone. HCI (Univar AR Grade) and 5 ·mL cone. HNO 3 (Aristar) were added to each beaker, which was then placed on a hot plate and allowed to gently reflux for 15 minutes. After the organic matter had been digested 1.0 mL cone. HCIO 4 (Univar AR Grade) was added directly to the solution. After digesting for a further hour, the solutions were allowed to cool and filtered into 100 mL volumetric flasks through Whatman No.541 filter paper. Portions of the thoroughly mixed solutions were used for metal determination. Aluminium, chromium, iron, manganese, zinc and high nickel concentrations were determined by inductively coupled plasma (Labtest Model V-25), while cadmium, lead, silver and low concentrations of nickel were analysed by flameless atomic absorption spectrometry (Varian SpectrAA-40). The results were evaluated using the Model 2 F-test of the twoway analysis of variance (Sokal and Rohlf, 1969) using the Macmillam ASYST Statistical Package on an IBM XT computer.

45

a.& Residentia l

40

,!!I

O

E lectroplater

6,

Tannery

RESULTS A large amount of data was collected but only results for those metals which showed highly significant (P <0.01) site differences are given.

Sewer slimes were collected fortnightly over a six week period, in order to determine whether metal content in slime varied with collection date. Significant differences (P < 0.01) in metal concentration in slime were observed for different sites. As expected, chromium in slimes collected adjacent to the tannery was found in significantly higher concentrations than in slimes from the other sites (Figure 1). Similarly, aluminium concentrations in slimes from the electroplater were significantly greater than in slimes from the other three sites (Figure 2). The metals found in high concentrations in the slime from both residential sites were aluminium, copper, and iron (Table 1). Although Burnside and Blair Athol were both non-industrial sites, the mean concentrations of aluminium and copper in slime collected at Burnside were approximately double those from Blair Athol.

DISCUSSION Effect of Collection Time

Biofilms are complex heterotrophic communities of bacteria, fungi, protozoans and other invertebrates, and are continually growing and sloughing-off due to shear stress. Consequently, it was thought that metal concentration in slime may vary over time. For example, slime collected just prior to sloughing (ie at maximum thickness) may have had a much higher metal content than slime collected just after sloughing (ie at minimum thickness). The two way analysis of variance results showed that for all metals analysed, the metal concentration in slime, based on fortnightly samples, did not significantly change. This conclusion however, must be viewed as preliminary because slime samples were only collected on three dates, and the effect of frequency of sampling may have been masked if the build-up/ sloughing cycle was shorter than the sampling cycle. Consequently, further investigations into sewer slime growth are required. The high iron content in Burnside slime, collected on 8.11.88, (marked * in Table 1) was most likely due to flecks of rust falling

35

i--

30

--

0

c 0 ;

§.

E l ectroplater

t:,

Tan nery

30

l!!

C 0

~

Cl

1: 20

!E

GI

u C 0

20

QI

u

0

C 0

E

0

:I

E

10

:I

·2

·e

~

0

:I

10

ci: 0

i

i

8/11/88

22/11/88

• 6/12/88

Date Fig. 1 - Chromium concentration in sewer biofilm from four sites: two sites in residential areas, one adjacent to an electroplater and one adjacent to a tannery. 20

Re sidential

0

i:.':'

01

E

·ee

• A

WATER February, 1990

:::--~ 8/11/88

22/11/88

6/12/88

Date

Fig. 2 - Aluminium concentration in sewer biofilm from four sites: two sites in residential areas, once adjacent to an electroplater and one adjacent to a tannery.


into the sewer during sampling. This highlights the necessity for care during sampling when dealing with heavy metals. Variations in Abundance of Slime

Although four industrial sites were originally selected for biofilm monitoring, two sites could not be sampled because there was insufficient slime. The reduction in slime may have been due to polJutants in discharges from adjacent industries causing the biofilm to slough or hindering regrowth of biofilm. Fortunately, a similar problem did not occur at either the electroplater or the tannery sites. One possible explanation for the sufficient slime at the electroplater site may be that this industry was surrounded by numerous residential dwellings. The higher organic loading at this site, contrasted to that at the discontinued sampling sites, probably assisted in the rapid regrowth of the slime on the sewer pipes adjacent to this industry. Consequently, the frequency at which sampling can be conducted, when this technique is employed, will be determined to a large extent by the rate of slime re-growth. This appears to be influenced by the proximity of the industry to residential dwellings or other sources of organic waste.

This observation may be explained by: The saturation of binding sites on the slime by chromium, thus preventing other metals being adsorbed. 2. The selective uptake of certain metals by the polymer, or by the slime microbial population. 1.

The Electroplater

The high aluminium concentration in slime from the electroplating site (Figure 2) was expected due to their industrial processes. Slime samples from the electroplater had the highest concentrations of lead, iron, copper and cadmium, although the latter was still a relatively low concentration compared to the other metals (the mean cadmium concentration over the three sampling dates was 42 µ.g ig dry weight of 'slime). The electroplater was surrounded by residential dweIJings which would provide a greater organic loading in the effluent passing this site compared with that at the tannery. Consequently, a more diverse and dynamic biofilm community could be present at the electroplating site. Also, residential effluent would be a sou~ce of a_wider spectrum of metals, and a continual supply of orgamc debns that would be available for complexing metals.

Metal Content from Different Sites

This survey identified large differences in metal content in slime between sites; this was particularly obvious for slime collected adjacent to industries known to employ certain metals in their industrial processes. Silver concentrations in slime were low at aIJ four sites over the sampling period, ranging from 2 to 30 µg i g dry weight of slime. This would be expected since silver is an expensive metal and losses would be avoided. Manganese was found in similar low concentrations (90 to 250 µg ig dry weight of slime) in slime from all sites. The Tannery

The high chromium concentration in tannery effluent was the reason for the highly significant (P < 0.01) site effect for chromium (Figure 1). The only other metals found in high concentrations in slime from this site were manganese (120 µgi g dry weight of slime) and iron (2,500 µgig dry weight of slime) which were in similar concentrations to those in slimes from the other sites studied. A grab sample of effluent from the tannery was taken in 1989 (Table 2). The metal that occurred in the highest concentrations was chromium, while iron and aluminium were next but in concentrations considerably lower than for chromium. In contrast the slime collected adjacent to the tannery had the lowest aluminium concentration of all slimes sampled. The manganese concentration in this slime was higher than the aluminium concentration, even though the reverse was found in the grab effluent. Table 1 Al, Cu, Fe in Slimes Sites:

I. Residential: Burnside, Blair Athol 2. Industrial: Tannery, Electroplater Metal Concentration (ug/ g dry wt of slime) Aluminium Copper

Iron

Collection date (1988)

22. 11

6.12

2976 *30040

8024

8264

22.11

6.12

8.11

22.11

5102

4800

3950

2234

2562

1676

1494

1816

477

498

517

5672

5086

3050

258

971

2006

II

16

13

2020

2036

4840

25380 31080 24320

2596

2376

2274

11260 10364

7800

Blair Athol Tannery Electroplater

8.11

8.11

SITE: Burnside

6.12

• This consid erably higher iron concent ration was suspected to be due to flecks of rust being knocked into sewer during the removal of the manhole cover.

Table 2 Metal concentration (mgl L) in grab sample of effluent from the tannery, collected on 1 March 1989. The grab sample was collected from the same site from which slime samples were taken in 1988. Al

Ca

Cr

Cu

1.62

192.6

211.4

0.14

Fe 7.59

Mg 185.1

Mn 0.35

Na

6491

Zn 0.81

Residential Sites

The main difference between the two residential sites was that predominantly household effluent entered the sewer in Blair Athol, whereas many light industries, eg service stations, food outlets, hairdressers, laundries, etc. discharged effluent into the sewer upstream from the Burnside sampling site. Klein et al. (1974) identified light industries, commonly found in residential areas, as significant contributors to metal contamination of effluents, which may explain the differences in metal ·concentration in slime between the two residential sites. Possible sources of metals found at the two residential sites in this survey are corrosion of plumbing materials and discharge of household chemicals. ' Just after World War II cast iron pipes were used for underfloor waste transfer in Adelaide in both residential and industrial establishments, while earthenware niping was used for external plumbing. Cast iron for piping was superseded by copper in the early 1950s, but the use of copper piping for waste transfer was discontinued due to increased cost. However, copper piping is still used for internal wastewater transport within multi-storey buildings. Currently, alJ water is transported within residences through copper piping and PVC piping is used extensively for both interior and exterior wastewater transfer. In older houses zinc galvanised pipes were also used for internal water transport. (R. Backshall, pers. comm.). Corrosion of piping may be a possible source of iron, zinc and copper, while zinc, tin, lead and cadmium may leach from PVC piping. These metals are used as stabilisers and additives_in the manufacture of synthetic rubber and PVC (Forstner and Whittman, 1983). Enzyme detergents have been found to contain trace amounts of iron, manganese, chromium, cobalt, zinc, strontium and barium (Angino et al, 1974). Furthermore, many organic compounds contain metal additives. For example gasoline contains tetraethyl lead; heavy duty oil contains lead; and lubricating oil is usually supplemented with molybdenum sulfide. These compounds may be added, albeit irregularly, to wastewater from residential dwellings and thus contribute to heavy metal contamination. Petrol was found on the sewer platform at Burnside on the last sampling date. However, no corresponding increase in lead concentration in the slime was detected. Aluminium and copper occurred in high concentrations in slime collected from residential sites. The mean concentration of aluminium at Burnside was approximately double that at Blair Athol. A possible reason for this may be differences in water supply between the two sites. The water supply to Burnside is unfiltered while the supply to Blair Athol is filtered. The untreated water supply to Burnside has

Continued on page 39 WATER February, 1990

21


Asset Replacement: Can We Get It Right? by R. D. S. CLARK

ABSTRACT The urban environment is one of the principal systems whereby we interact with the biosphere. Since, at the basic level, water is one of the most pervasive and vital elements of the biosphere, the management of water for city dwellers must be a high priority area to commence investigations of ways to improve our environmental interactions. The cost bulge in the replacement schedule for water and sewerage assets expected in the early part of the next century will coincide with the opportunity to provide a fundamental review of the performance of the existing systems against revised criteria. The processes involved in the development and acceptance of the criteria will be less painful for those organisations which adopt more open and receptive management styles. It is hypothesised that the development of more efficient and sustainable water systems will come about in conjunction with the adoption of more particularised and personalised technologies, within an organisational structure which provides greater autonomy to the managers of the various system components and the strengthening of the independence and influence of the regulatory agencies.

THE PROBLEM The provision of water supply and sewerage services in South Australia is, in general, based on large scale, high throughput systems relying on a relatively small number of water sources and waste disposal sinks. These are linked together via the customer network through extensive conveyance systems. The systems represent a major engineering achievement, bringing very high standards of service to a high proportion of the population. However, in South Australia, as in most other States, many elements of the systems are approaching the end of their economic life and will have to be rehabilitated or replaced. If all the physical assets used in the provision of the water services had to be replaced, it has been estimated that the cost would be of the order of A$9000 million. Projections made, show that amounts varying between approximately A$80 to A$160 million (1989) per year will have to be found over the 25 year period from about the year 2000 to cover the costs of the accelerated levels of asset replacement during that period (SA.Govt, 1987). The initial projections were based on a one-for-one replacement assumption, under which the solution to the problem was perceived to be financial in character, requiring the establishment of improved accounting methods, funding arrangements, pricing policies and the preparation of replacement and funding schedules. Scope obviously exists, however, for technical innovation-to extend the life of the assets and to seek savings in re-design of the systems and their components. Thus, whilst the problem is still recognised as one of the largest facing the Engineering and Water Supply Department, the magnitude of the financial burden has still to be fully defined. This paper seeks to expand on this area of technical innovation and argues that more attention should be paid to this aspect, for reasons which are explained. If replacement criteria are chosen which are appropriate to updated economic, social and environmental knowledge and expectations, and emerging technologies are used in appropriately innovative ways by managers provided with incentive to seek them out, it is hypothesised that water and sewerage services could be provided in a significantly different form, and possibly at a much lesser cost than would be the case if the technological changes were not made.

ENVIRONMENTAL PRESSURES FOR CHANGE In 1983 the General Assembly of the United Nations set up the World Commission on Environment and Development to examine 22

WATER February, 1990

Richard Clark is a Principal Engineer in the Engineering and Water Supply Department of the South Australian Government. He has over 25 years experience in water resource assessment, analysis and planning in government, university and private enterprises and has worked in two developed and two developing countries.

R. D. S. Clark

the state of the world environment and to formulate a global strategy to direct future development. The report of the Commission contained in the book 'Our Common Future' (Brundtland,1987) has been well received and has become the catalyst for the development of many parallel national programs. The basis of these programs is the recognition that the present global levels of energy and resource use and of waste discharge are not sustainable. A corollary of the main thesis is that, assuming that greater global equity is strategically and morally desirable, the over-riding imperative of global change can only be achieved if the developed nations (which constitute one fifth of the world's population but are responsible for four fifths of its eq.ergy and resource consumption and waste production) make the greatest changes in their life styles. Global change therefore involves all of us, in both our private and professional lives. The major imperative identified by the Commission is that all nations must start to recognise and include the cost of actual or potential social and environmental damage in their development planning processs, so that future development can be sustained. How sustainability should be defined or achieved is a matter of ongoing debate, however, few would now deny the need for change. Consequences of any move in this direction must be a rise in the costs of raw materials and energy and the corresponding development of new capital- and energy-saving technologies. The optimistic view is that, provided the criteria for change are adequately identified and compatible programmes carried out, the opportunity may exist for those organisations which can adapt most quickly to the challenge, to secure themselves an advantageous position in what may become a rapidly expanding market for new methods. The timeframes usually quoted for the changes to take place are of the order of a few decades only. This is of significance, since it is well within the gestation period and expected life-span of the water supply and sewerage assets which will need to be replaced during the accelerated replacement period. From the perspective of the water industry, environmental awareness (and hence the development and application of appropriate regulations) is relatively high in the areas affecting the inputs to the water systems, but low in the areas impacted either directly or indirectly by the systems.

CONSTRAINTS TO CHANGE IN THE WATER INDUSTRY Within private industry, adaption to the environmental challenges will come via the preferences of customers for more environmentallysound products placed before them by speculative entrepreneurs, and via more stringent 'environmentally compatible' government regulations. Examples of this are already with us.


The parallel for similar mechanisms for change in the water industry is, however, seriously compromised by the monopoly position of the water authorities and the blurring of their business and regulatory roles. · · This is not to say that the water industry is not able to change. In fact the need for the water industry to adapt to many significantly changed circumstances is well recognised by its leaders and many programmes of change have been initiated from within. However, any popular external pressures for major change in the environmental area may be perceived as 'anti-engineering' and 'anti-commercial' and thus may be resisted as being too threatening to the industry's traditions and established operations. A tantalising but possibly risky means of ensuring a separation of the business and regulatory roles could lie in privatisation. Recent trends world-wide are increasingly recognising that the 'true' role of government lies in its regulatory role. Many of the customer service roles of a water authority could, and possibly should be undertaken as private enterprises, provided that satisfactory solutions could be found for two interrelated problem areas. That is, if: • appropriate technologies could be found to reduce the need for a monopoly structure, so that privatisation would not merely replace a public monopoly by a private one, and • an appropriate mechanism could be established to develop the regulations under which the 'new' private/competitive providers of the water services could be established and operated, with all due safeguards for public health and well-being. This problem, of course, has received much attention recently in the United Kingdom. It is believed, however, that as defined in the two part form above, little attention has been given to the solution of the technological component as being of equal strategic importance to the solution of the larger problem of providing a more accountable and responsive framework for the provision of water services.

THE INAPPROPRIATE TECHNOWGY FACTOR In pursuing the thesis that a brighter water future may come about in parallel with the introduction of new technologies, it can be queried whether some of the old technologies were ever really appropriate. There are three facets to be considered here. The first is the inappropriateness of certain technologies in general. Schumacher (197 5) has argued that the economies of scale which are reaped by some sectors and/ or generations of society, are often only achieved at the expense of others, and/or of the present or future environment. All undertakings relying on economies of scale should therefore be critically reviewed in terms of their equity and sustainability. Moreover, the technology used and the form of the organisation using it are mutually dependent. Hence, the growth of large, interlinked and complex water systems has been both a cause and a result of the parallel growth of large monolithic organisations to operate them. The inevitable establishment of government funded and operated monopolies, resulting from these monolithic tenden.cies, has resulted, directly or indirectly, in institutionalised inefficiencies. Some of these are beginning to emerge as the water industry starts to put itself on a commercial footing, but it is suggested that many of the environmental and societal costs are still to be revealed. The second consideration is the importation of technologies into Australia which are not suited to the local environment. Australia has been particularly vulnerable to this on account of its cultural links to countries with vastly different climate, water and soils systems and there is an ongoing need to identify and translate these differences into locally appropriate engineering products. The third consideration is the need to review the assets in the light of updated knowledge about the impacts that the services exert on public health and well-being and their efficiency of operation under situations where the quality of the water sources is deteriorating. In this area the most outstanding factor is the recent recognition of the high cost of increased levels of salinity on society. Only cursory attention was originally given to the design of the water systems to enable them to be operated to minimise the impacts of poor water quality.

The water treatment works and operation~! facilities which have been subsequently developed are essentially 'add-ons' to pre-existing systems. The danger exists that these new, large and expensive subcomponents will add to the momentum of a system whose overall performance has not been critically assessed against changing longterm requirements.

MECHANISMS AND PROCESSES OF CHANGE Like most water authorities in Australia the EWS Department has already started major reforms (EWSD, 1987). Included in these is the adoption of a more commercial approach to its undertakings, in order to increase economic efficiency and partly offset the effects of reductions in treasury allocations. Evans (in Blandy and Walsh, 1989) has proposed a greater degree of autonomy and commercial accountability for managers of sub-components of the system as a means of accelerating the move towards greater economic efficiency. Such an organisational disaggregation and commercial emphasis might also be a key to the more rapid achievement of smaller, more responsive, sociable and efficient systems. These characteristics are usually those also associated with sustainable systems and would be compatible with: • the promotion of strategies for greater system flexibility, innovation and personal choice for consumers, including improved mechanisms for definition of standards of service. • the promotion of user-group shareholding in units of the system which can be operated and maintained by competitive tender. • the incorporation of multi-purpose uses of existing or replaced assets as a means of reducing unit costs by inclusion of a wider range of beneficiaries. Attempts to achieve greater economic efficiency by introducing commercialisation will, however, merely heighten the need for a wiser, stronger and more vital regulatory body to identify and protect other values of the larger society, which have no representation in the immediate 'market place' represented by these commercial units. Such actual or potential conflicts are described by Synnott (1989). ' Because of the widespread acceptance of the monopoly position of the water authorities, there is an understandable underestimation of both the importance and difficulty of the establishment of effective regulatory bodies, capable of developing the criteria under which, amongst other water management concerns, the asset replacement of the major water systems should take place. Both the establishment of the regulatory bodies and the maintenance of their effectiveness will be an ongoing task, requiring input from persons with qualification and experience in the definition and design of sustainable futures. The existing South Australian Water Resources Council does not have this responsibility. It is suggested that both the establishment and the operation of· the regulatory bodies, under which the all-important criteria for improved sustainability would be developed, should comply with the main requirements for: • independence from the providers of the water services in the establishment of the environmental and social impact criteria and the assessment of compliance to the regulations set up. • the development of processes for the exchange of information between the regulatory body, the service providers, and the areas of public interest and concern. • the integration of the purposes and effects of water management regulations with those of other environmental and social goals, whilst still maintaining the necessary levels of specialisation. • a greater degree of democracy in the appointments to the regulatory bodies.

TARGET AREAS FOR PERFORMANCE REVIEW AND CHANGE It is not difficult to identify areas of likely inefficiency in the South Australian systems which involve the use of technologies which are inappropriate for some or all of the reasons given earlier. Familiarity with any comparable water systems in Australia would undoubtedly reveal similar instances. For example: WATER February, 1990

23


• Systems analyses aimed at minimising overall costs are already showing the benefit of operating the existing systems in a significantly different manner, on the bas_is of water quality.(Crawley and Dandy, 1989). The extension of the analyses to investigate alternative system design has obvious implications. • Surface water storage and transmission via long pipelines often incur inherent quantity and quality inefficiencies, which could probably be reduced by better utilisation and innovative management of the local surface and groundwater hydrology in the location of the demand. An example of this is given in the next section. • One hundred percent of all reticulated water is treated to a drinking standard at a cost of A$30 million/year. Seventy five percent of this water is used for irrigation or toilet flushing, for which purposes the treatment standard is unnecessary. Ironically, a significant growth in the sales of bottled water and home watertreatment units has been a feature during this same period of increased expenditure on the public water treatment programs. • The demand for water services generally increases slowly and yet large scale technologies have been employed for system augmentation which require them to be designed and constructed many years in advance of the bulk of the expected requirement. The present water supply system in South Australia has been oversized for the past 30 years and is likely to remain so for the next 20 years. • Mains sizes and pressures are governed by peak demand rates. The introduction of on-site storage and/or differential day/ night water use meters and pricing structures could significantly reduce the peak demands. Decisions made in the past were mostly based on the best information to hand and under a very different social climate. The important thing is to recognise the need and opportunity to change in the light of our new knowledge and circumstances and to strengthen the mechanisms that will enable the changes to occur, and to keep on changing in the future, as appropriate. Certain heartening changes have already started to take place. For example, the recent concern for reducing the impact of sewage and urban stormwater discharges on the marine environment in South Australia could have large implications on both the water supply and sewerage systems.(EWSD, 1989). Firstly, if effluent from sewage treatment plants is to be used for the more extensive growing of crops, as has been suggested, the whole rationale of continuing with large scale treatment works situated near the sea comes into question. The whole system now becomes one of recycling. Why not recycle on a smaller scale and avoid the large pumping costs, sewer replacement costs and saline groundwater 'pollution' of the sewage resource being handled? Second, if urban stormwater is to be managed to improved quality standards before discharge to the sea, its potential value for other purposes automatically rises. An investigation has recently identified the economic feasibility of using stormwater to recharge groundwater beneath Adelaide. The envisaged system incorporates a we_tland scheme which provides additional multi-purposes of marine pollution reduction, flood mitigation, passive recreation, ecological diversification and amenity enhancement.(Fisher and Clark, 1989). The utilisation of local resources in this manner has the potential to reduce the need for capital intensive, single purpose facilities. A whole range of small or medium scale technologies already exist which have the potential to provide individual or community scale water service systems. These have generally been disparaged by the water authorities, even in the face of popular demand. It is probable that the pressures for change will require that these, or modifications, be re-investigated with respect to their sustainability. Such systems enable direct or indirect competition to take place with respect to their manufacture and maintenance and provide greater potential for user choice. In order to commence the process of exploration of the concept of sustainability in relation to the provision of urban water services, the Engineering and Water Supply Department is in the process of formulating a series of inter-Departmental investigations in a developing area adjacent to Adelaide. These will include: 24

WATER February, 1990

• the increased re-use of effluent from the Bolivar sewage treatment works. • the incorporation of wetlands in multipurpose schemes including the recharge of groundwater for irrigation supplies. • the redesign of urban stormwater systems for improved water quality. • the review and testing of alternative low energy water conservation systems. A high level of public participation will be sought in these investigations.

SUMMARY AND CONCLUSION The urban environment is one of the principal systems whereby we interact with the biosphere. Since, at the basic level, water is one of the most pervasive and vital elements of the biosphere, the management of water for city dwellers must be a high priority area to commence investigations of ways to improve our environmental interactions. Built form and lifestyles are strongly interlinked. Since both have inertial qualities, they tend to perpetuate each other. Changing one or both of these can only be accomplished as a community activity. Since the services provided by the public utilities are also highly interdependent, any restructuring to achieve a more sustainable urban future can only be undertaken as a government-led, interagency activity. The Engineering and Water Supply Department in South Australia is undergoing major reforms. Pressures for change are likely to increase and these are likely to have significant, but as yet largely unrecognised, impacts on the way future water system assets are deployed and operated.

REFERENCES Brundtland G.H . (1987) (Chairman, U.N. World Commission on Environment and Development), Our common future, Oxford Universjty Press. Blandy R. and W. Walsh, (editors) (1989). Budgetary stress: The South Australian experience. Allen and Unwin, 1989. Crawley P.D. and G.C. Dandy, (1989). Optimum reservoir operating policies including salinity considerations. Hydrology and Water Resources Symposium, Christchurch NZ. EWSD, (Dec. 1987). The role and management cff an Australian Water Authority into the 1990's - New directions, Engineering and Water Supply Department, Adelaide. EWSD (Aug. 1989). Strategy for Mitigation of Marine Pollution in South Australia, Engineering and Water Supply Department, Adelaide. Fisher A.G. and R.D.S. Clark, (Apr. 1989). Urban storrnwater - A resource for Adelaide, EWSD, Adelaide. S.A. Government (Apr. 1987). 51st Report of the Public Accounts Committee, Adelaide. Schumacher E.F. (1975). Small is beautiful: &onomics as if people mattered, Harper and Rowe, New York, 1975. Synnott M., (Dec. 1989). Market mechanisms and the resolution of conflict in water management. Paper to symposium on Resolution of conflict in Australian water management, CRES, ANU, Canberra, Dec. 6-8, 1989.

INDUSTRIAL WASTE GRANTS, 1990 These research projects are funded and administered by the Melbourne Board of Works. The 1990 waste research projects will deal with recycling of industrial effluents associated with the photographic and paper bleaching industries, the safe disposal or reuse of solvents from solvent waste effluents, and reuse of industrial wastewater. The grants for 1990 are: • $19 497 to Swinburne Institute of Technology Centre for Applied Colloid Science to research into the removal and recycling of anionic contaminants and their reuse in sulfer and nitrogen. • $24 300 to Camp Scott Furphy Pty Ltd and Mike Lyons and Associates whose project will look at the minimisation of volatile organic emissions and effluents by a solvent extractions system. • $22 440 to Binnie and Partners Pty Ltd whose project will investigate the potential for reuse of wastewater in Melbourne. Further details are available from Greg Axford, Melbourne Board of Works, telephone 615 5861.


Ion Chromatography - A Technique ft>r the Analysis of Inorganic Ions in Environmental Samples by T. A. BOWSER and B. J. WILDMAN ABSTRACT This paper briefly reviews the technique of ion chromatography for the analysis of inorganic ions in environmental samples. Three major choices are presented for dealing with matrix interference problems in environmental samples when analysing anions using ion chromatography. Analysis of cations and transition metals is also mentioned.

INTRODUCTION Traditionally, the analysis of inorganic anions in samples of environmental origin has been performed using a variety of wet chemical and spectroscopic techniques. Although of great utility, .many of these techniques are subject to matrix interferences and, commonly, only one anion at a time is analysed. The use of ion chromatography for surveillance monitoring of ppb-ppm levels of anions is now a recognised technique. (Jandik and Cassidy, 1989), particularly for the routine determination of chloride, fluoride, bromide, nitrate, nitrite, phosphate and sulphate in water. (Shipgun et al, 1988). It has effectively replaced conventional colorimetric, electrometric or titrimetric methods, and is included in the 16th Edition of the AmWWA "Standard Methods for for the Examination of Waters and Wastewaters"l. Ion chromatography is a separation technique: analytes of interest are separated from each other and from most interfering substances before quantitation, so that the major anions can ,be analysed sequentially in one run. The sample is injected into the ion chromatograph and carried through an ion exchange separation column by the eluent. A precision pump maintains constant flow rate. Within the column, ionic species exhibit varying degrees of attraction to the separation column packing and migrate through the column at different rates. This separates the sample into discrete ionic components. After separation, the ions are carried by the eluent into a detector which responds to the amount of each component and this response is recorded in the form of a chromatogram. The chromatogram identifies each component by retention time and quantitation is based on the magnitude of the response.

ANALYSING ENVIRONMENTAL SAMPLES There are three basic approaches to dealing with the matrix interferences that sometimes occur when analyzing aqueous environmental samples by ion chromatography.

Timothy Bowser works as the Jon Chromatography specialist for Waters Australia Pty Ltd. Following graduation from the Capricornia Institute of Advanced Education in 1979, he worked for Queensland Alumina Ltd, then G/axo Australia as a research chemist and later became laboratory manager for G/axo Australia (Primary Division). Mr Bowser joined Waters in 1987. T. Bowser

Bill I Wildman works as a methods development chemist in the Ion Chromatography Group at Waters Chromatography Division of Millipore, Milford, Mass. US.A. He submitted data to the Environmental Protection Agency for acceptance of single column ion chromatography for the analysis of nitrite and nitrate in drinking water. He received his Master's degree in Inorganic Chemistry from the University of Vermont.

Figure 2 demonstrates the sensitivity of the method for nitrite and nitrate.

Change of eluent Most separations are performed using an eluent of borate/ gluconate (Schmuckler et al, 1986) whi~h can accommodate samples with a pH between 5 and 9. Outside this pH range, perturbations can occur in the baseline that may interfere with quantitation. (Erkelens et al, 1987). In an effort to extend the useful operating range of this eluent, modifications of the ratios of borate and gluconate were made by McClory and Warren (1989). This eluent allows the analysis of samples with pH between 2 and 12. Figure 3 shows the results from a reagent water sample which was acidified with sulfuric acid to pH2. The top chromatogram (Figure 3A) was obtained using the standard borate/gluconate eluent. Note the

1. Change the detection technique to one that is more selective for

the analytes of interest.

A

ppm

4

1. 2. 3. 4. 5.

2. Alter the separation technique by a change in eluent or even a change of the separation column. 3. Treat the sample before analysis to remove interferences.

Carbonate Chloride Nitrite-N Nitrate-N Sulfate

2.3 0.1 7.5 12.8

Change of detection technique The most common detection mode is measurement of the changes in ion conductivity of the eluate. However, in certain cases, measurement of UV absorbance can be used, particularly for nitrite, nitrate and bromide. An example is demonstrated in Figure 1. The sample was the effluent from a silicon chip manufacturing facility, and the primary analytes of interest were nitrite-N and nitrate-N. Figure IA shows the result from the use of a conductivity detector. The high concentration of cations in the sample resulted in considerable perturbations in the early part of the chromatogram, and masking of the nitrite and nitrate peaks. Changing the detection system to UV absorbance at 214nm resulted in Figure lB. In 1989, the utility of this method has been recognised by the U.S. EPA. The Federal Register will list it as B-1001 "Best Method for the determination of Nitrate in Water using Single Column Ion Chromatography".

4

B v---------'

L_ 25 Minutes

Fig. 1 - A: Conductivity detection of an effluent waste water sample, and B: Reduced baseline interferences using UV detection at 214nm. Column: IC Pakâ&#x201E;˘ A HC Eluent: Standard Borate/ Gluconate WATER February, 1990

25


negative perturbation in the baseline, referred to as a system peak. Use of the modified borate/gluconate eluent eliminated the system peak (Figure 3B).

Pretreatment Many approaches have been used to pretreat samples before analysis. Frequently environmental samples contain organic substances in addition to analyte anions. These organics do not for the most part interfere directly with anion analysis, however they may bind to the "backbone" of the separator column and occlude ion exchange sites. Samples containing such organics are pretreated with solid phase extraction (SPE) cartridges, typically containing hydrophobic material such as octadecylsilane-bonded silica (Cl8). Other potential interferences present in environmental samples are high levels of alkali and alkaline earth metals such as sodium, calcium and magnesium, in addition to extremes of pH in the case of effluent wastewaters. Approaches to deal with these interferences are more difficult. One cannot easily add an inorganic acid, e.g. HCl, to an alkaline sample in order to reduce pH, since the added counter-ion, chloride, may be an interferent. Commonly, strong ·cation exchange resins in the acid form have been used in these cases;

however, the resins must be scrupulously rinsed with high purity water before use in order to prevent possible anionic contamination. Loss of ions or contamination from the sample preparation devices led to a search for alternative means of sample pretreatment. Cox et al (1989) have demonstrated the use of hollow fibres for sample pretreatment in ion chromatography. The Millitrap™ H + Membrane Cartridge is a hand-held device that contains a nonporous cationic membrane to pretreat samples with high pH, high levels of alkali and/or alkaline earth metals, and samples with elevated carbonate levels, without loss or gain of the analyte anion concentrations. Samples are introduced to the device via a Luerlok syringe. The low dead volume of the cartridge, about 250µL , requires the use of less than lmL of sample. The effect of the cartridge for pretreatment of a drinking water sample is shown in Figure 4. The sample contained high amounts of cations in addition to carbonate and when injected direct into the ion chromatograph, resulted in Figure 4A. Pretreatment removed the cations and carbonate peaks and restored the baseline (Figure 4B). Many enviromental samples contain a wide concentration of ions. Commonly, Australian water samples show low levels of nitrite, 6

3 4

3

1 Chloride 2 Nitrite-N 3 Nitrate-N

A Before

32 ppb 68 ppb

5

2 r-

0

d 11 Minutes 4

0

10

5 Time (min)

6

4. Chloride

B

5. Nitrate 6. Sulfate Atter

Fig. 2 - EPA Method B1001 Analysis of Nitrite, Bromide and Nitrate with UV Detection Column: IC Pak™ A 3

Eluent: KOH 2

1. Cation peak 2. Organic acid

3. Carbonate

5

11 Minutes

A

Fig. 4 - Chromatograms of drinking water sample, A: before, and B: after, treatment with the MillitrapTM H' membrane cartridge.

~ 0

Column: IC Pak™ A HR Detection: Conductivity

0 N

1. Fluoride 2. Chloride 3.

2

B

Nitrate

4. Phosphate 5. Sulphate

Standard Borate/G luconate 1 . System peak 2. Sulfate

~

8 N

Modified Borate/Gluconate

Fig. 3 -

A: Low pH system peak using standard borate/gluconate, and B: The elimination of the system peak using modified borate/gluconate. Column: IC Pak™ A Detection: Conductivity

26

WATER February, 1990

20 Minutes

Fig. 5 - Environmental Water Sample, containing high levels of Chloride. Phosphate 4ppm

Nitrate: 2ppm

Column: IC PakTM A HC Detection: Conductivity


fluoride and phosphate in the presence of high levels of chloride. These types of samples are best analysed using a column which is capable of efficiently separating relatively high concentrations of analytes, while maintaining short run times and good retention stability. The Waters IC Pak A HC (High Capacity) can be used to analyse such samples. An example is given in Figure 5.

metals are selectively derivatised with 4- (2,Pyridylazo) re-sorcinol · (PAR) to form a UV absorbing complex (Figure 7.) Monovalent cations, divalent cations and anions do not react with PAR and are therefore removed as interferences. Cu Pb Zn Ni Co Cd Fe Mn

~0

ANALYSIS OF CATIONS

u

100

Since the first ion chromatograph was commercially introduced in 1975, ion exchange separation has been continually improved. Today mono and divalent cations, including transition metals, can be separated and measured in almost all sample matrices. Figure 6 demonstrates the separation of monovalent and divalent cations. The separation column contains cation exchange resin of low capacity. The eluent is a dilute solution of a mineral acid (nitric acid) or an ethylenediammonium salt. The sensitivity of this method is excellent with detection limits in the low ppb region. Transition metals are routinely monitored in waste water discharge and hazardous wastes. The separation uses a reverse phase column dynamically coated with octanesulphonic acid to yield an efficient variable capacity cation exchange column. After separation, the E ::,

mV

80

1 ppm 1 ppm 1 ppm 2 ppm 5 ppm 2 ppm 1 ppm 1 ppm

60 40

20

\

\ 5

0

10

15

Minutes

Fig. 7 -

Transition Metals Analysis

Column: uBondapak C18 Eluent: S0mM Tartaric Acid 2mM Sodium Octanesulfonate pH3.4 Detector: M440 546nm PAR Derivatization Post Column

·1: 0

CONCLUSION

E E

E E ::, ::,

<{

'g £ (f)

::J

5

0

E ::,

Working Standard Lithium 1 ppm Sodium 5 ppm 10 ppm Ammonium Potassi um 10 ppm

'ill

~

15

10 Time (min)

E ::, ·~ C

0,

""

::;:

E

::,

Q

u"'

'1

E

::,

C\J

·~

d

Working Standard Magnesium 2 ppm Calcium 4 ppm Strontium 6 ppm Barium 16 ppm

CD

0

5

Time (mi n)

Fig. 6 -

10

14

Analysis of monovalent and divalent cations. Column: IC Pak™ C Detection: Conductivity

BOOK REVIEW WATER VICTORIA; A RESOURCE HANDBOOK Department of Water Resources Victorian Govt. Printing Office, RRP $34.95. This superbly-produced 312 page reference book covers the location, quantity, quality and use of the water resources of the State. It will be followed during 1990 by "An Environmental Handbook" and "The Next 100 Years". It has been prepared to enable resource managers to take a Statewide view of the limited resources, and to plan for efficient water use. It is also designed to educate Victorians in the need to conserve water and

There are three major choices for Ion Chromatography in dealing with matrix interference problems in environmental samples. The first is to alter the mode of detection. A detector which is specific for an analyte may mask the presence of interferences, for example, the analysis of nitrite and nitrate by ultraviolet rather than by conductivity detection. Another is to change the eluent or analytical column. A modification of the borate/gluconate eluent was presented. The third is to use sample preparation devices. The Millitrap™ device was introduced. The Millitrap™ will neutralize high pH samples and reduce or remove cationic or carbonate interferences without affecting anion levels. Ion Chromatography has additional capabilities for the analysis' of cations, including transition metals in most sample types.

REFERE~CES AmWWA "Standard Methods for the Examination of Water and Wastewater", 16th Edition. Cox, J.A., Dabek-Alotorowska, E., Saari, R., Tunaka, N. (1989) Jon exchange treatment of complicated samples prior to ion chromatographic analysis Analyst 113: p.1401-1404. Erkelens, C., Billiet, H.A.H., De Galan, L., De Leer, E .B. (1987). Origin of system peaks in single-colum n ion chromatography of inorganic anions using high pH borate-gluconate buffers and conductivity detection J Chromatogr. 404: p.67-72. Jandik, P. and Cassidy, R.M., Editors (1989). Advances in Ion Chromatography Vol I. (Century International, Franklin Mass.). McClory, J. and Warren, D. (1989). Modification of borate gluconate eluent for analysis of anions of ground water Advances in Ion Chromatography, op.cit. p.261-268 . Schmuckler, G., Jagoe, A.L., Girard, J.E., Buell, P.E. (1986). Gluconate-borate eluent for anion chromatography: nature of the complex and comparison with other eluents. J Chromatogr. 3S6: p.413-422. Shipgun, 0., and Zolotov, Y.A. (1988). lon Chromatography in Water Analysis(John Wiley & Sons, New York N.Y.)

manage it properly, and as such has been distributed to every secondary and tertiary educational institution in the State. Section I. Statewide Review. Chapter 1. The Resource: Reviews climate and geography, and the surface and groundwater quantity, quality and variability. Chapter 2. Historical Background: The development of the legal and administrative systems for control of the water resources and wastewater disposal over the 150 years of European settlement. Chapter 3. Financial and Economic Framework: Revenue and expenditure, subsidies, tariffs, allocations, groundwater permits. Chapter 4. The Major Systems: The operation of the ten systems from the Melbourne Board through to the WimmeraMa)lee Stock and Domestic Supply.

Chapter 5. Water Use. Current uses for irrigation, urban and industrial, rural stock and domestic purposes, and future development, (in light of the fact that annual use is already about half of the theoretical potential resource). Chapter 6. The Way Forward: Towards more efficient use and resource management. Includes discussion on salinisation control and agricultural policies. Section II. River Basin Summaries. 220 pages describing each of the 39 AWRCdesignated basins: geography, hydrology, groundwater, history and land use, water use, major storages, water quality, water and wastewater services, land use control for catchment protection. Section Ill. Appendices: Chronology, glossary, geologic time-scale, bibliography. WATER February, 1990 27


Effect of Changing from Chlorination to Choloramination on Microbiological Quality by D. A. CUNCLIFFE, P. E. CHRISTY, B. ROBINSON and R. P. WALTERS ABSTRACT Chlorination has been replaced by chloramination for a number of South Australian water supplies. The effect of the change on a range of pathogenic, indicator and nuisance micro-organisms was investigated. The results show that the use of chloramination improved the microbiological quality of water supplies. The frequency of isolation of Naegleria spp., Naegleria fowleri, total coliforms, Escherichia coli, Aeromonas spp, standard plate count organisms, heterotrophic iron bacteria and fungi were all reduced when chloramination was used. The improvements reflect the relative stability of chloramines in distribution systems.

A ll the authors work at the State Water Laboratory, Engineering and Water Supply Department David Cunliffe graduated B.Sc. (Hons, Microbiology)fromAdelaidein 1972, and completed his Ph.D. at Flinders in 1976. He was a Senior Research Officer at Flinders before joining the Microbiology Section in 1980.

INTRODUCTION The ideal disinfectant for water supplies is one which would rapidly inactivate micro-organisms in source waters and persist to provide protection against recontamination or regrowth within distribution systems. Chloramination is the only disinfection .process, currently in use, that fulfils the second requirement for long distribution systems. However, laboratory experiments have shown that chlorarnines require relatively long contact times to inactivate micro-organisms (Hoff and Geldreich, 1981; Wolfe et al. 1984). Despite this disadvantage, chloramination has been effectively used to inactivate coliform bacteria and reduce numbers of standard plate count organisms in water supplies (Brodtmann and Russo, 1979; Norman et al. 1980; Shull, 1981; Mitcham et al. 1983). In South Australia, chloramination was first introduced in March 1983 to control the growth of Naegleriafowleri, the causative agent of primary amoebic meningo-encephalitis (Carter, 1970), in a rural water supply. This first trial was successful and chloramination has since been introduced for a number of supplies either to control the growth of N. fowleri or to improve the bacteriological quality of the supply. In general these supplies incorporate long pipelines as part of their distribution systems. After disinfection, water can be detained in some of these systems for over 28 days before supply to consumers. Prior to the introduction of chloramination each of the supplies was treated by chlorination. This paper summarises the microbiological impact of the change to chloramination for a number of water supplies, including its effect on the presence of N. fowleri and the traditional indicators of microbiological quality; total coliforms, Escherichia coli and standard plate counts. In addition the effect of the change on the presence of Aeromonas spp., heterotrophic iron bacteria and fungi was also examined. Aeromonas spp. are ubiquitous free-living inhabitants of fresh water and have been isolated from both chlorinated (Burke et al. 1984b; Millership and Chattopadhyay, 1985; Kooij, 1988) and unchlorinated water (Burke et al. 1984a). Each of the three species of motile aeromonads have been associated with enteric infections (Champsaur et al. 1982; Gracey et al. 1982; Agger et al. 1985; Altwegg, 1985; Burke et al. 1987). Iron bacteria are non-pathogenic nuisance organisms which, however, can cause fouling and discolouration of water supplies (Olson and Nagy, 1984; APHA, 1985). Fungi have been isolated from water distribution systems and include allergenic, pathogenic and toxigenic species (Olson and Nagy, 1984; Rosenzweig et al. 1986).

MATERIALS AND METHODS Water Samples

All samples were collected by the procedure described¡ in the World Health Organization 'Guidelines for Drinking Water Quality' (1984). Chlorine and Monochloramine Concentrations

Total chlorine residuals were used as a measure of the monochloramine concentration in water. Free and total chlorine residuals were determined, in the field, by titration with ferrous ammonium 28

WATER February, 1990

D. Cunliffe

Peter Christy graduated B.Sc (Hons, Zoology)fromMonash in 1972, worked at the University of Adelaide, and joined the Protozoology Section in 1981.

P. Christy

Bret Robinson has an M.Sc, Zoology from Adelaide and is Senior Protozoologist, concerned with the ecology and control of eg Naegleria, Acanthamoeba, Giardia and Cryptosporidium.

Bret Robinson

Reg Walters heads the Microbiological Section. After graduating B.Sc (Applied Microbiology) from Queensland, he has had 20 years experience in the examination and disinfection of water supplies and, the ecology of enteroviruses, Legionella and iron bacteria.

Reg Walters sulphate with N,N-diethyl-p-phenylenediamine as a colorimetric indicator (APHA, 1985). Microbiological Analyses

Analyses for amoebae were performed as previously described by Esterman et al. (1987). Total coliforms and E. coli were enumerated using membrane filtration techniques developed from those described in Standard Methods (APHA, 1985). Analysis for total coliforms was performed using resuscitation on lauryl tryptose broth followed by incubation on M-Endo LES agar. Confirmation was performed by testing for the ability to produce gas from lactose in 24-48h at 35°C in EC broth (Difeo). Analysis for E. coli was performed using a modified form of the M-FC agar of Geldreich et al. (1985). In the modified agar, called DFC, the rosolic acid has been omitted, as recommended by Presswood and Strong (1978) and the aniline blue dye


has been replaced with 0.2 g/L phenol red. After filtration membranes are incubated on DFC for 4h at 30°C and then 18h at 44.5 °C. Circular yellow colonies are regarded as presumptive E. coli. Confirmation was performed by testing for the ability to produce gas from lactose in 24h at 44.5 ° C in EC broth (Difeo) and indole from tryptophan in 24h at 44.5 ° C in tryptone water (Oxoid). Analyses for Aeromonas spp. were performed as described by Cunliffe and Adcock (1989). Standard plate count organisms were enumerated by the pour plate method using plate count agar (APHA, 1985). Two plates were poured for each sample; one was incubated at 20°C for 72h while the other was incubated at 35°C for 24h. Heterotrophic iron bacteria were enumerated by the spread plate method using ferric ammonium citrate medium (APHA, 1985). The plates were incubated at 30°C for 7d. Fungi were enumerated by a membrane filtration method. After filtration membranes were incubated on Rose Bengal Agar (Oxoid) for 5 days at 20°C. The Rose Bengal Agar was supplemented with kanamycin sulphate (105 i.u. per litre).

RESULTS Since 1983, chlorination has been replaced by chloramination for a number of South Australian water supplies. Characteristics of the supplies included in this assessment are summarised in Table 1. The physical quality of the water ranged from turbid unfiltered water from the River Murray to highly coloured water from natural catchments and then to filtered water of low turbidity and colour. In general the data included in this report were from samples collected within the 18 months before and after the introduction of chloramination for each system. Naegleria fowleri has been detected in a limited number of South Australian water supplies. Between 1983 and 1984, chloramination was introduced for three of the supplies listed in Table 1 to control N. f owleri. Results show that the change to chloramination increased the median disinfectant residual and reduced the frequency of isolation of N. f owleri and Naegleria spp., in general, in all three supplies (Tobie 2). Naegleria fowleri was only detected in one sample collected after the introduction of chloramination. The frequency of isolation of total free-living amoebae was reduced in two of the three systems but they were still detected in over 500Jo of all samples. In addition to the control of N. Jowleri, chloramination was introduced in several supplies in attempts to improve the overall microbiological quality of the reticulated water. Results of analyses for bacteria and fungi in samples collected from the water supplies listed in Tobie 1 are summarised in Table 3. The introduction of chlorarnination led to an increase in the median disinfectant residual from 0.2 mg/L to 2.6 mg/L and to concommitant reductions in the frequency of isolation of each of the organisms examined. The smallest reductions were observed for the standard plate counts (20°C and 35°C) and fungi. After the introduction of chloramination 400Jo of samples contained at least one of these types of Table 1 Physical characteristics of chloraminated water supplies. Distribution System

Starting Date for Chloramination Water Supply

Tailem Bend-Keith

March 1983

Yorke Peninsula

November 1983

JamestownPeterborough

October 1984

Myponga

July 1987t September 1987 September 1988 July 1989

Morgan-Whyalla Warren Strathalbyn-Milang

• Median results

t

Chloramination ceased in February 1988

River Murray water, unfiltered Prior to September 1986, unfiltered water from a number of sources Prior to September 1986, unfiltered wate r from the River Murray Unfiltered natural catchment Filtered since September 1986 Unfiltered natural catchment A mixture of natural catchment and River Murray water, unfiltered

organisms (Table 3). The median counls for each, however, were reduced. More detailed analysis of the results presented in Tub le 3 shows that the numbers of these organisms were lower when chloramination was used to disinfect the supplies (Figure 1). Only 3.5% of samples from chloraminated supplies contained more than 100 fungi per 100 mL; lOOJo contained more than 100 standard plate count organisms (20°C) per mL and 50Jo contained more than 100 standard plate count organisms (35 °C) per mL. In comparison 300Jo of samples from chlorinated supplies contained more than 100 fungi per 100 mL; 470Jo contained more than 100 standard plate count organisms (20°C) per mL and 220Jo contained more than 100 standard plate count organisms (35°C) per mL.

DISCUSSION The replacement of chlorination by chloramination for the disinfection of some South Australian water supplies resulted in improvements in microbiological quality. The frequency of isolation of Naegleria spp., N. fowleri, total coliforms, E.coli, standard plate count organisms, Aeromonas spp., heterotrophic iron bacteria and fungi were all reduced after the introduction of chloramination. In the three systems in which chloramination was introduced to control the pathogenic N. fowleri, only one sample out of a total of 580 samples tested, after the change from chlorination, contained this amoeba. However, other free-living amoeba were detected in over 500Jo of samples collected after the introduction of chloramination. These amoebae can colonize sediments and it is speculated that this provides a constant source of the organisms detected in the water column. The high frequency of isolation probably reflects the one weakness of chloramination, its relatively slow rate of inactivation of micro-organisms. The National Health and Medical Research Council "Guidelines for Drinking Water Quality in Australia" (1987) state that 950Jo of Table 2 Amoeba results before and after the introduction of chloramination. Median

Free or total

Distribution System

FREQUENCY OF,DETECTION OF AMOEBAE Free living Naegleria spp,

Amoebae

Number of chlorine* Positive Samples Samples mg / L No. %

N. fowleri

Positive Samples Positive Samples No. % No. %

CHWRINATION Tuilem BendKeith

116

<0.1

88

75.9

28

24.1

27

23.3

Yorke Peninsula

499

0.1

207

41.5

29

5.8

12

2.4

JamestownPeterborough

86

<0.1

63

73.3

15

17.4

1.2

0.7

CHLORAMINATION Tuilem BendKeith

140

0.2

98

70.0

2

1.4

Yorke Peninsula

369

2.6

182

49.3

14

3.8

0

0

JamestownPeterborough

71

2.1

34

47.9

1.4

0

0

• Total chlorine residual used as a measurement of chloramine residual

Colour HU*

Turbidity NTU*

17

53.5

6

32.0

Table 3 Bacteriological and fungal results before and after the introduction of chloramination*

Disinfectant

5

65.0

59

4.1

3

0.5

63

9.0

10

41.0

Coliforms Free or total Total E. coli Chlorine / JOOml 1100ml

Standard Plate

Het. Iron spp. Bacteria Fungi 1100ml / ml / JOOm l Aero-

monas

Counts

20'C / ml

3S'C / ml

CHWRINE No. of samples No.Positive % Positive Maximum Minimum Median

6215

< 0.1 0.2

6215 986 15 .9 210 0 0

6215 2835 2835 332 2187 1896 5.3 77.1 66.9 210 100,000+ 100,000+ 0 0 0 0 360 21

250 215 216 157 94 182 62.8 43 .7 84.3 92,000 62,000 410,000 0 0 0 0 27 8

5106

5106

5106 22 0.4 16 0 0

1776 722 40.7

329 305 311 36 47 198 10.9 15.4 63 .7 670 81,000 18,000 0 0 0 2 0 0

5.0

CHLORAMINES No.of Samples No. Positive % Positive Maximum Minimum Median

88 6.2 0.1 2.1

1.7 60 0 0

1776 1051 59.2

10,000+ 10,000+ 0 3

0 0

• Summary of results for samples collected from all water supplies listed in Table I

WATER February, 1990 29


particular have been the subject of increasing attention and the Netherlands health authorities have establish!d guideline values for these bacteria (Kooij, 1988).

Chloramine a

b

C

50

"'

The improvements in microbiological quality achieved by the use of chloramination almost certainly reflects the stability of chloramines in the distribution systems. The maintenance of residual disinfectant throughout water supply systems is difficult when using chlorine. Initial disinfection is effective but there is little protection against recontamination or regrowth of micro-organisms within the distribution system.

40

a." E

.jJ

30

0

"'" c" u"

~

20

ACKNOWLEDGEMENTS This investigation was supported in part by a grant from the Urban Water Research Association of Australia.

10

0

0

1-10

11100

101 - 100 110 00

0

1-10

11-

REFERENCES

100

Number of Organisms

Chlorine 40

d

e

"'

" "

}

30

(/)

0

"'"

20

~ C

";;;u

10

a..

0

1-10

11100

101 - 10011000

Number of Organisms

Figure 1 - Frequency distribution of numbers of standard plate count organisms and fungi in samples collected from water supplies when treated with either chlorine or chloramines. (a) and (d) standard plate counts (20°C)/mL; (b) and (e) standard plate counts (35°C)/mL; (c) and (f) fungi/IOOmL.

samples should not contain any coliform bacteria per 100 mL of water and that no sample should contain any faecal coliforms per 100 mL. Further, while no guidelines were included for standard plate counts, it is suggested that numbers of these organisms (grown at 37°C) would not be expected to exceed 100 per mL in a well maintained system. Overall, when disinfected by chloramination, the water supplies listed in Tobie 1 conformed to the guideline for total coliforms while 99.60"/o of samples were free of E. coli (used as a measure of faecal coliforms) and 95.00Jocontained less than 100 standard plate count organisms (35°C) per mL. When chlorine was used as the disinfectant only 84.1 OJo of samples were free from coliform bacteria, 94.7% from Ecoli and 78.2% contained less than 100 standard plate count organisms (35°C) per mL. The reduced presence of the non-indicator organisms, Aeromonas spp., fungi and heterotrophic iron bacteria when supplies were chloraminated was also significant. They have been identified as common inhabitants of water distribution systems and include a mixture of pathogenic and nuisance organisms (Olson and Nagy, 1984; Rosenzweig et al. 1986; Kooij, 1988). Aeromonas spp. in

30

WATER February, 1990

Agger, W.A., McCormick, J.D. and Gurwith, M.J. (1985). CLinical and microbiological features of Aeromonas hydrophila associated diarrhea. Journal of Clinical Microbiology, 21, 904-913. Altwegg, M. (1985). Aeromonas caviae: An enteric pathogen. Infection, 13, 228-230. APHA (1985). 'Standard Methods for the Examination of Water and Wastewater', 16th Edition (American Public Health Association, Washington, D.C.) Brodtmann, N:V. and Russo, P.J. (1979). The use of chloramine for reduction of trihalomethanes and disinfection of drinking water. Journal of the American Water Works Association, 71, 40- 42. Burke, V., Robinson, J., Gracey, M., Petersen, D., Meyer, N. and Haley, V. (1984a). Isolation of Aeromonas spp. from an unchlorinated domestic water supply. Applied and Environmental Microbiology, 48, 367-370. Burke, V., Robinson, J., Gracey, M., Petersen, D. and Partridge, K. (1984b). Isolation of Aeromonas hydrophila from a metropolitan water supply: seasonal correlation with clinical isolates. Applied and Environmental Microbiology, 48, 361-366. Burke, V., Robinson, J. and Gracey M, (1987). Enterotoxins of Aeromonas species. Experentia, 43, 368-369. Carter, R.F. (1970). Description of a Naegleria isolated from two cases of primary amebic encephalitis, and of the experimental pathological changes induced by it. Journal of Pathology, 100, 217-244. Champsaur, H ., Andremont, A., Mathieu, D., Rottman, E. and Auzepy, P. (1982). Cholera-like illness due to Aeromonas sobria. Journal of Infectious Diseases, 145, 248-254. Cunliffe, D.A. and Adcock, P. (1989). Isolation of Aeromonas spp. from water using anaerobic incubation. Applied and Environmental Microbiology, 55, 2138-2140. Esterman, A., Calder, I., Cameron, S., Roder, D., Walters, R., Christy, P. and Robinson, B. (1987). Determinants of the microbiological characteristics of spa pools in South ' Australia. Water Research, 21, 1231-1235. Geldreich, E.E., Clark, H .F., Huff, C.B. and Best, LC. (1985). Fecal-coLiform-organism medium for the membrane filtration technique. Journal of the American Water Works Association, 56, 208-214. Gracey, M., Burke, V. and Robinson, J. (1982). Aeromonas-associated gastroenteritis. Lancet, ii, 1304-1306. t Hoff, J.C. and Geldreich, E.E. (1981). Comparison of the biocidal efficiency of alternative disinfectants. Journal of the American Water Works Association, 73, 40-44. Kooij, D:V.D. (1988). Properties of aeromonads and their occurrence and hygienic significance in drinking water. Zentralbla/1 fur Bakteriologie Mikrobiologie und Hygiene, B, 187, 1-17. Millership, J.E. and Chattopadhyay B. (1985). Aeromonas hydrophila in chlorinated water supplies. Journal of Hospital Infection, 6, 75-80. Mitcham, R.P., Shelley, M:W. and Wheadon, C.M. (1983). Free chlorine versus ammonia-chlorine: disinfection, trihalomethane formation and zooplankton removal. Journal of the American Water Works Association, 75, 196-198. National Health and Medical Research Council (1987). 'Guidelines for Drinking Water Quality in Australia' (Australian Government Publishing Service, Canberra). Norman, T.S., Harms, L.L. and Looyenga, R:W. 1980. The use of chloramines to prevent trihalomethane formation. Journal of the American Water Works Association, 72, 176-180. Olson, B.H. and Nagy, L.A. (1984). Microbiology of potable water. Advances in Applied Microbiology, 30, 73-132. Presswood, W.G. and Strong, D.K. (1978). Modification of M-FC medium by eliminating rosolic acid . Applied and Environmental Microbiology, 36, 90-94. Rosenzweig, W.D., Minnigh, H. and Pipes, W.O. (1986). Fungi in potable water distribution systems. Journal of the American Water Works Association, 78, 53-55. Shull, K.E. (1981). Experience with chloramines as primary disinfectants. Journal of the American Water Works Association, 73, 101-104. Wolfe, R.L., Ward, N.R. and Olson, B.H. (1984). Inorganic chloramines as drinking water disinfectants: a review. Journal of the American Water Works Association, 76, 74-88. World Health Organization (1984). 'Guidelines for Drinking Water Quality' (World Health Organization, Geneva).


Mechanical Mixers: An Alternative Destratification Technique. Myponga Reservoir, South Australia by P. J. SUTER and G. KILMORE ABSTRACT Myponga Reservoir which supplies the southern-most suburbs of Adelaide with unfiltered water has a history of taste and odour problems due to growth of cyanobacteria. A compressed air destratification facility has operated since 1980/81 to control phantom midge (Chaoborus sp.) but has not effectively destratified the reservoir, nor controlled the algal growth. During the summer of 1988/ 89 trials using submersible mixers were undertaken as an alternative method to destratify Myponga Reservoir. During the trial period, October 1988 to May 1989, the chemical, physical and biological characteristics were monitored to evaluate the effectiveness of the mixer facility. The mixers were as effective but more efficient than the continuously operated aerator. The mixers used less power than required by a compressed air system adequate to destratify Myponga Reservoir, and provided a greater operational flexibility.

INTRODUCTION Artificial destratification has been used for phytoplankton control method in South Australian reservoirs since 1977. In 1980 an aerator was introduced into Myponga Reservoir to control Phantom Midge (Chaoborus). This facility overcame the Chaoborus problem (Suter, 1987) but did not totally destratify the reservoir and therefore had little effect on the taste and odour problems associated with high phytoplankton growth. The temporary aerator facility consisted of three joined lengths of soaker gardenhoses with numerous small perforations. A compressor of 50 L/s capacity was attached by a non-perforated hose and the diffuser was lowered to a depth of 23m. It was operated from November 1980 and each summer thereafter until March 1988. It was effective in controlling Chaoborus but in the 1986/ 87 summer the compressor failed for long periods allowing Chaoborus to again enter the distribution system. In addition potential problems associated with cyanobacteria prompted an investigation into the installation of a more effective destratification facility. To provide an adequate aeration facility at Myponga Reservoir required a lOOkW compressor which could deliver a free air flow of 115 L/ s. Due to the lack of available space for compressor housing, inadequacies of the available power supply, the scenic attraction and¡tourist usage of the area, the potential noise problems associated with an air compressor, and difficultie of placement because of potential interference with the main road across the dam wall, an alternative to aeration was considered. Consultants considered that both aeration and mechanical mixing were feasible and provided the necessary data for both. The logistic restraints influenced the decision to investigate the use of submersible mixers mounted on the dam wall. In March 1988 three Flygt mixers were installed and operated for a warranty trial period from late March to July 1988. This trial commenced when the reservoir was isothermal and the effect of the mixers could not be assessed. However it did indicate that the mixers required protection from corrosion. The mixers were again operated from 28 September 1988 until May 1989. Effects on the physical, chemical and biological quality of Myponga Reservoir are discussed.

STUDY AREA Myponga Reservoir is situated 54 km south of Adelaide on the Myponga River. The reservoir supplies unfiltered water to the southern suburbs of Adelaide and to some country centres on the Fleurieu Peninsula. Reservoir characteristics are given in Table l, and sampling locations and mixer placements are shown in Figure 1. 32

WATER February, 1990

Phillip Suter is a biologist at the South Australian State Water Laboratory, Engineering and Water Supply Department. He obtained his Bachelor of Science (Honours) degree from the University of Adelaide. He was employed by the Museum of Victoria before taking up his present position with the Biology Section at the State Water Laboratory in 1981. P. Suter

Geoffrey Ki/more graduated with an Honours degree in Civil Engineering from the University of Technology, Loughborough, UK. in 1971. After working for State Government, Local Government and Consulting Engineers, he joined the Engineering and Water Supply Department in 1976 and has specialised in the water treatment field. His present position is Senior Water Treatment Engineer. G. Kilmore

MYPONGA RESERVOIR

MIXER PLACEMENT

G) ..Sampling

Locations

The Mixers and their Operation

Three submersible mixers were mounted on separate guide rails on the wall of the reservoir. They° were placed as follows; Position 1: 30m south of the outlet tower Position 2: 15m south of the outlet tower Position 3:

15m north of the outlet tower. TABLE 1. Myponga Reservoir Characteristics.

Capacity above Low Water Level Catchment Area Surface Area at Full Supply Level (FSL) Perimeter Length at FSL Length of Reservoir Maximum Depth Maximum Supply Depth Mean Depth Depth of Offtake Valves below FSL

26800 124 280 20.3 5.8 43 33 .2 9.6

ML km ha km km m m

m

4

9.75 m

3 2,1

16.46 m 33.2 m


Each mixer system consisted of: • a "FLYGT" 4430 mixer with a 3.1 KW motor and mixer blades of 2.5 m diameter. • a guide rail to 30 m below FSL for the two .southern mixers and 25 m for the northern mixer. • a davit arm with winch to raise and lower the mixer. • a mounting frame which enabled the mixers to be orientated from 30° to 90° from the vertical. Flygt assisted the Department in re-designing the mounting frames and guiderails to provide the facilities required to deploy the mixers. The installation enabled rapid changing of position of each mixer, and the orientation of each could also be altered as required.

From the temperature profiles the thermal stability of the reservoir was calculated. The stability is defined as the minimum theoretical energy required to mix a reservoir from an initially stratified to an isothermal state (Davis, 1980). Thermal stability can be calculated using the following formulae: n

Potential Energy of Mixed System (PEM) = g E

Pim

I

Vi hi

n

Potential Energy of Stratified System (PES) = g E Pis Vi hi I

where Pim and Pi s are mean water densities of each lm layer of water from the mixed and stratified cases respectively (Kg/ m 3) Vi is the volume of each layer lm deep (m 3) hi is the height from the bed of the reservoir to the centroid of each lm layer (m) g is the acceleration due to gravity (ms - 2) n is the total number of layers. Stability = PEM - PES (J)

RESULTS

Fig. 1 - Flygt 4430 Mixer during installation

On 28 September 1988 one mixer was put into service at Position 2 at a depth of 18m below FSL and angled at 60 ° to the vertical. The other two mixers were put into service on 28 October 1988 with the mixers at Position 1 at 18m depth and Position 2 at 10m, both angled at 45 °. On 24 November 1988 all mixers were lowered with mixers 1 and 2 at 25m and 3 at 18m below FSL. All mixers were angled at 45°. Following an increase in the cell numbers of Anabaena sp 3 in the water column, the mixers were raised on 16 December 1988 to increase the surface turbulence. Mixers 1 and 2 were raised to 10 m and 3 to 16m below FSL. Mixer 2 was angled at 60 ° to the vertical to increase turbulence. The mixers were left at this level until mid March when mixers 1 and 2 were about Sm from the surface due to the fall in reservoir level. On 17 March the mixers were lowered so that mixer 1 was positioned at 15m, 2 at 10m and 3 at 21m below FSL. They operated at this depth until the end of May. The operational changes are summarised in Table 2. Table 2 Summary of operational changes of mixer position and orientation Date

28/ 9/ 88

28/ 10/ 88

24/ 11 / 88

16/ 12/88

!Orn 60°

23m 45°

18.5m60 °

18m 45°

23m 45°

16m 45 ° !Om 600

5m

!Orn 60°

!Om 45°

!Om 45 °

!Om 45°

Mixer I 2 3

For most determinands there was little difference between the concentrations/values from location 1 and 4 from equivalent depths. Therefore only results from location 1 are presented unless location 4 is specifically mentioned. Isotherms from July 1988 to May 1989 are given in Figure 2. In late August 1988 surface heating raised the surface temperature from 12 to 16°C. One mixer was installed on 28 September and the isopleths were depressed. Surface heating was again evident in October, but when all three mixers were installed on 28 October a strong thermocline formed around 22m below the surface. This was 4m below the deepest mixer. On 24 November the mixers were lowered, and the epilimnion depth increased with the thermocline depressed to 26/27m. Some surface heating was evident in December,• but this was rapidly dissipated into the water column. To offset this heating and to LEGEND

-

E=3

E f-

I

0

"

1 mixer

3 mixers

3 mixers lo wered

10

S2 w I

20

w (')

:::>

30

<( (')

J

A

s

0 1988

N

J

D DATE

F

M

A

198 9

17/ 3/ 89

15m 45° 60°

Mixer depths are relative to the water surface

SAMPLING PROGRAM Samples were taken from location 1 near the offtake tower, and during the operation of the mixers additional samples were taken from location 4 in the main body of the reservoir, some 750m from the dam wall. Water samples were taken from a Sm integrated surface column (IC), and from depths of 10m, 20m and 30m using a Van Dorn sampler. Nutrients (Total Kjeldahl Nitrogen, Oxidised Nitrogen, Ammonia, Total Phosphorus and Soluble Phosphorus) and heavy metals (Total and Soluble Iron and Manganese) were measured weekly while colour, turbidity, algal biomass (chlorophyll-a) and phytoplankton numbers were measured twice per week from each depth at each location. Tumperature and dissolved oxygen profiles were taken twice per week at each location at lm intervals using a Yellow Springs Instrument Model 51B.

increase the surface turbulence the mixers were raised on 16 December with the deepest mixer at 16m below the surface. The thermocline was maintained between 20m and 25m depth until the reservoir became isothermal in April 1989. During February and March a near-record hot spell of 11 days with temperatures exceeding 36°C for 9 of the 11 days was experienced. The surface temperature of Myponga Reservoir increased less than 1°C as the thermal energy was distributed rapidly into the water column, as indicated by the depression of the 20°C isotherm. Dissolved oxygen concentration followed a similar pattern to that shown by the temperature data. During the mixer trial period oxygen depletion was evident below the thermocline, with concentrations less than lmg/ L below 25m depth from January to mid March 1989. Figure 3 shows the thermal stability of Myponga Reservoir from July 1988 to May 1989. During the period of mixer operation the thermal stability was lower than previously recorded during the summer. WATER February, 1990 33


450

a

b

The chlorophyll-a concentration at location 1 IC is shown in Figure 4. During the mixer trial period the chlorophyll-a concentrations at 10m depth were similar to the IC samples, but usually slightly lower at 20m. At 30m chlorophyll-a did not exceed 3µg/L until the reservoir was mixed in April. A log plot of total cell numbers is given in Fig. 5. Numbers rarely exceeded 10000 cells/mL and were usually between 1000 and 10000 for the trial period. During the mixer trial period cell numbers were similar at the IC, 10m and 20m samples but were almost an order of magnitude lower at 30m depth until the reservoir mixed in April, when numbers were similar at all depths. Anabaena was the major problem genus requiring copper sulphate treatment on three occasions during the study (Fig. 6). There appeared to be no reduction in numbers due to the mixer operation. The mixers did not appear to change the abundance of any other genus with the possible exception of Attheya which was not recorded after November 1988.

e

d

C

LEGEND 1 mixer in ( 28 / 9 / 88 )

a

400

C

3 mixers in 128 / 10/ 881 mixers lowered lo ma,< , dept h ( 24 /11/ 88 )

d

mixers raised ( 161 12/881

e

mixers lo wered ( 17/ 3 / 89 )

b

350

=;

:a

300

>-

t= cc! en

250

<(

IU)

_, <( :a

200

w

150

er: I

I-

100 22

50

a

0

s

A

J

0

D

N

J

M

F

DATE

:::;

c - mixers lowered to max. depth 124/1118 8 ) d • mixers raised 116/ 12/ 88>

16

e - mixers lowered 11713/ 891 CuSO4 treatment

0) E

e

d

C

b • 3 mixers in 128 / 10/ 88)

18

A

b

LEG END a : 1 mixer in ( 28 / 9 / 88)

20

,j, •

14

<(

When only one mixer was operating in September the thermal stability was reduced from 260MJ to lOOMJ in 12 days. The one mixer was insufficient to maintain low stability as the temperature increased. With three mixers in place in October the thermal stability fell from 310MJ to 200MJ in 7 days after a lag phase of 5 days. Stability fell to 70MJ some 23 days after the peak of 310MJ. As soon as the mixers were lowered in November the stability increased to a peak of 285MJ in late December as the surface waters heated. After the mixers were raised in mid-December the stability fell after some 5-6 days lag, and was maintained below 160MJ until overturn at the end of March. During the near-record hot spell in late February - early March there was an increase in the stability, but not to the same extent as observed during hot spells in previous years. The thermal stability at location 1 was usually lower than at location 4 in the centre of the reservoir. The pattern of change was similar, but the effect of the mixers at location 4 was usually observed about a week later than at location 1. Colour and turbidity were not affected by the mixers, and remained much the same as in previous years. During the operation of the mixers concentrations of nutrients and heavy metals were low, and similar at the surface, 10m and 20m depths, but were elevated at 30m during the period of low dissolved oxygen concentration in the hypolimnion (Table 3). This is due to the release of nutrients and heavy metals from the sediment. At turnover the concentrations were elevated throughout the water column. The highest concentrations recorded at the surface, 10m and 20m depths were at turnover.

-'

12

>I a..

10

er:

8

-'

0

0 -' I

(.)

6 4 2 0 J

A

s

0

Chemical results from monitoring of mixer operation in Myponga Reservoir July 1988 to May 1989. p

Fe

NH,

TKN

Sol

Tot

Sol

Tot

Sol

Tot

mg/ I

mg/ I

mg/ I

mg/ I

mg/ I

mg/ I

mg/ I

mg/ I

mg/ I

J

i

CuSO 4 treatment

MIXERS OPERAT IN G

-g

100000

<I)

10000

0

z -' -'

(.)

100

-'

10

I-

0

I-

t

1000

w

<(

t

t 11

J

A

S

0

N

D

DATE

J

F

M

1989

., LEGEND

CuSO 4 treatment

MIXERS OPER ATIN G

Loe. 1: IC Minimum Maximum

.04 <.005 .33 .036

.82 < .005 1.25 .038

0.40 .10

.34 .69

.44 < .005 .110 .89

.006 .130

.05 <.005

.12 < .005 .041 1.45

.033 .110

.35 .71

.43 < .005 .110 .75

.010 .120

Loe 1 !Om Minimum Maximum

.29

.048

Loe. I 20m Minimum Maximum

.08 .31

.052

.75 < .005 1.51 .041

.033 .160

.34 .70

.41 < .005 1.73 .100

.011 .140

<.01 .41

.006 .440

.77 1.25

.050 .270

.40 1.09

.60 < .005 2.03 .970

.019 1.040

.005

Loe 1 30m Minimum Maximum

31 to 35 samples for each determinand

34

WATER February, 1990

.015 .090

A

M

F

LEGEND

,l, ..

Mn

NO,

D

DATE

1988

Table 3 -

N

1988

DATE

1989

A

M


DISCUSSION Aeration is the most common destratification technique used in Australia to overcome a number of water supply problems, such as offensive taste and odours, dirty water, discoloured clothes, slime deposits in pipes, and to control phantom midge (Chaoborus) and cyanobacteria growths (Brown, 1986). In South Australia aerators have been operating in Barossa, Warren, Little Para, Kangaroo Creek, Happy Valley, Myponga, and Hindmarsh Valley Reservoirs. The Barossa and Kangaroo Creek Reservoir facilities were temporary and operated for only one season. All these facilities have increased the epilimnion volume, but total destratification has not always been achieved. During periods of high air temperatures and still conditions, surface heating and reduced mixing depth result at all reservoirs. In Myponga Reservoir the compressed air facility was expensive to operate, often suffered breakdowns, and was not effective in maintaining a deep mixing depth. Regular blooms of cyanobacteria each summer resulted in the need for copper sulphate treatment to ensure the potability of the water supply. In the 1988/89 summer three mechanical mixers were used to destratify Myponga Reservoir. This was the first use of mechanical mixers to destratify a reservoir in Australia, and a reservoir of this size in the world. Mechanical techniques have been used for hypolimnetic aeration in North America and Europe, but the use of mixers to destratify a reservoir is restricted to one in Illinois. Raman and Arbuckle (1989) reported total destratification of Lake Eureka (Illinois) using mechanical mixers, but this lake with a capacity of7ML and a depth of 5.5m was considerably smaller than Myponga Reservoir. Therefore comparison of results is limited. The aeration and mechanical mixers did not fully destratify Myponga Reservoir, but unlike the aeration f!lcility, the mixers did maintain a deep mixing depth throughout the trial period with only one exception in December 1988. The inability of the mixers to fully destratify the reservoir, and the period of shallow mixing depth were probably due the timing of the start of the mixers and the empirical nature of mixer placement and orientation. It is likely that the mixer operation can be optimised and automated using a direct link with a thermistor chain. When the mixers were first installed at a maximum depth of 18m thermal stratification become established at approximately 20m. After the mixers were lowered to the full depth of 23m (1 and 2) and !Om (3) on 24 November the thermocline was lowered to 26127m, suggesting that had at least one mixer been set at 23m stratification may not have been established. With all the mixers at maximum depth there was insufficient turbulence at the surface to rapidly mix the warm surface water being heated by solar inputs throughout the epilimnion, a condition which also exists with aeration techniques. This resulted in the surface heating in December 1988. When all mixers were raised the depth of the thermocline was maintained between 20 and 25m depth, some Sm below the deepest mixer, and the turbulence created by the shallower mixers effectively transfered heat rapidly into the epilimnion. This was noticeable in February/March 1989 when Adelaide experienced a near-record hot spell. Oxygen levels closely followed the thermal structure with the hypolimnion oxygen concentrations below 2mg/I. The concentrations of Iron, Manganese, Ammonia, Total Phosphorus and Soluble Phosphorus were high at 30m depth due to release from the sediments. The Nitrate concentration was also higher, but this was probably due to the ammonia oxidising during sampling, and therefore the NH 3 concentrations were probably higher than recorded. Concentrations above 20m depth were not elevated, and remained similar at all depths throughout the study. Phytoplankton biomass, (chlorophyll-a) was low throughout the trial period when the reservoir was strongly stratified all summer but with a deep thermocline at approximately 20-25m depth. Reynolds and Walsby (1975) noted that Anabaena and Microcystis were confined to lakes where the ratio of mixing depth (Zm) to euphotic zone (Zeu) was 0.3-2. In lakes where the ratio was greater than 0.8-2.5 Oscillatoria was the likely dominant genus. In Myponga Reservoir the euphotic zone is rarely greater than 2m and during operation of the mixers when Anabaena was dominant, the Zm:Zeu usually exceeded 5-10. Steinberg and Hartmann (1988) considered that a mixing depth greater than 15m would exclude the cyanobacteria, and intermittent mixing due to artificial destrati-

fication with changes on a scale of a few days would also exclude this group. In Myponga Reservoir this does not appear to be the case, with Anabaena capable of growth when mixing depth exceeded 20m. The mixing depth measured at locations 1 and 4 indicated a mixing zone of 20-25m. However, this may not truly represent the mixing depth over the whole reservoir. In the shallow bays and edges of the reservoir the mixing depth is limited by the reservoir bottom. Approximately 50% of the area of Myponga Reservoir is shallower than 6m. This corresponds to a mixing depth to euphotic depth ratio of 3:1 or less. Therefore the maximum mixing depth measured in the deep body of the reservoir does not truly represent the overall mixing characteristics. Anabaena may be growing successfully in the shallower areas, and inoculating the main body of the reservoir by wind action or the mixing process. Once in the deeper water Anabaena growth may be light-limited due to deep mixing, but the cell numbers are maintained from the shallow zones. The cell counts and chlorophyll concentrations indicate effective mixing in the deep water, with chlorophyll concentrations similar from the surface to 20m. The cell numbers of Anabaena remained low, but copper sulphate treatment was recommended at cell numbers less than 1000 cells/mL to ensure no taste and odour problems were experienced in supply. The one occasion while the mixers were operating that chlorophyll-a concentration exceeded lOÂľg/L, in December 1988, was probably caused by the lowering of the mixers thereby reducing the surface turbulence. Surface heating produced a lens of warm water at the surface, in which Anabaena numbers increased rapidly. The mixers may have acted to concentrate the Anabaena filaments into this lens by pumping those filaments at depth up to a point where their buoyancy could override the mixing effect. At the time of copper sulphate treatment the chlorophyll-a concentration was 12Âľg/L, and cell numbers exceeded 2000/ mL.

CONCLUSIONS The mechanical mixers which were used to destratify Myponga reservoir in 1988/89 were successful in stopping surface heating and dispersed the heat energy rapidly into the epilimnion. The mixers as operated were not successful in totally delitratifying the reservoir, but they were effective in reducing the phytoplankton biomass although unable to eliminate the cyanobacteria. The bathymetry of the reservoir may be vital for the effectiveness of destratification in eliminating the cyanobacteria. '\Vhere significant areas of the storage are shallow and near the limits of light penetration conditions may be suitable for cyanobacterial growth. The shallow bays may act as sources of contamination into the reservoir body as a whole. The mixers produced similar epilimnion depths to the aerators but were also able to maintain effective mixing at the surface; a deeper mixing depth, and reduced phytoplankton biomass. Without full meteorological data it is difficult to calculate the relative efficiencies of each destratification system. Energy input by each facility can be calculated using electrical units, and on this basis alone the mixers consumed a total of 9.3 kW compared with 100 kW for a compressor. Therefore the cost of operating these mixers was significantly less than a compressor providing equivalent mixing characteristics. In addition the operation of the mixer system was more flexible than an aeration facility because each unit could be rapidly raised or lowered to provide turbulence at the depth required. These advantages make such mixer installations worthy of consideration as a cost-effective alternative to the traditionally used compressed air facilities.

ACKNOWLEDGEMENTS We wish to thank Flygt (Australia) and Prenco Equipment Pty Ltd for their co-operation in these trials.

REFERENCES Brown, I.K. (1986). Review of the application of aeration/ destratification techniques in Australian surface water storages. Dept. Local Govt., Queensland 55pp. Davis, J.M. (1980). Destratification of reservoirs - A design approach for perforatedpipe compressed-air systems. Water Services, 84(1014): 497-504. Raman, R.K. and Arbuckle, B.R. (1989). Long term destratification in an Illinois lake. J.A.W.W.A., : 66-71. Reynolds, C.S. and Walsby, A.E. (1975). Water Blooms. Biol. Rev. Cambridge Philosophical Soc., 50: 437-481. Steinberg, CW. and Hartmann, H.G. (1988). Planktonic bloom- forming cyanobacteria and eutrophication of lakes and rivers. Freshwat. Biol., 20: 279-287 . Suter, P.J. (1987). Phantom midge (Chaoborus sp) in Myponga reservoir and water supply distribution system: The effect of aeration. Tech . Pap. A.W.W.A 12th Fed. Conv. , Adelaide. 193-201.

WATER February, 1990

35


TECHNICAL NOfE

Why is some of our water so coloured? P. NELSON, E. COISARIS and J.M OADES Australian Centre for Water Treatment and Water Quality Research

ABSTRACT Work examining a pair of catchments in the Mt Lofty Ranges, South Australia, has shown that soil properties have a major influence on the amount of dissolved organic carbon (DOC) in streams. The ability of the soils to retain organic matter, coupled with the flow path of water through the soils, can largely account for differences between DOC levels in different streams. The higher the clay content in the soil, the greater the retention of DOC. One . of the implications of these findings is that land use controls designed to improve water quality may not necessarily reduce DOC levels.

INTRODUCTION When water is supplied to domestic users, one of the major aims of treatment is disinfection. However, the presence of dissolved organic carbon (also known as colour, dissolved organic matter, humic material, gilvin, gelbstoff, etc.) and turbidity (or particulate matter) make disinfection difficult. Dissolved organic carbon (DOC) and turbidity are also undesirable in their own right. DOC and turbidity, along with salinity, are all natural water quality problems which may be altered to varying extents by man. Turbidity for example is usually considered to be a man-induced problem caused by the erosion of cultivated lands, although it is clear that in many parts of Australia, high levels of turbidity are a natural phenomenon. In the same way naturally high salt concentrations in many streams and rivers are being increased by agricultural land management practices. Much less is known about the sources of DOC.

SOURCES OF DOC Coloured water is commonly thought to be associated with maninduced water quality problems such as nutrient pollution, but highly coloured waters also emanate from areas of natural bushland, a particular case being the mountain waters of Tasmania. In other cases swampy areas are often assumed to be the source of origin even though they may be small or even non-existent in the catchments. In the Mt. Lofty Ranges catchment areas in South Australia (which supply approximately 600Jo of Adelaide's water supply), Hine and Bursill (1987) found that stream DOC values covered a wide range (2 to 26 mg/I), and that neither land use nor any other causative factor could explain the variation. Although point sources such as dairies and septic tanks are known to produce high effluent DOC concentrations, non-point sources were thought to be of greater importance. It was therefore decided that the nature and sources of DOC should be investigated in more detail. In an AWRAC funded project, two small catchments (Lawless, 3.0 km 2 and Retreat Valley, 1.3 km 2) both with no point sources of DOC, were chosen, described and instrumented for stream sampling. Grab sampling in 1987 had established that although the catchments had similar land use (grazing of improved pastures), and climate (800 mm rainfall) the concentrations of DOC were considerably different. After 1.5 years of sampling, the mean flow event DOC concentrations were 20 mg/I in Lawless and 8 mg/I in Retreat Valley. Lawless catchment is mostly flat, with a mean slope of approximately 30Jo, while Retreat Valley is steep with a mean slope of approximately 200Jo. It was proposed that this difference in slope, through its effect on residence time of water in the soil, and coupled with the presence of swamp areas in Lawless, would explain the difference in DOC levels. However, associated with the difference in topography is a geological difference which is reflected in the soils. In Retreat Valley the soils are loam over red clay developed 38

WATER February, 1990

Paul Nelson

M. Oades

E. Cotsaris

Paul Nelson - B.Agr.Sci. with Honours in Soil Science from University of Adelaide, 1986, is currently employed as Research Officer in the Department Soil Science, Waite Agricultural Research Institute. Evangelo Cotsaris, BSc.(Hons), A.RA.CL is employed as a scientific officer at the State Water Laboratory, Bolivar, South Australia. Professor Malcolm Oades is Professor of Soil Science at the Waite Agricultural Research Institute.

on shale, while in Lawless the soils are loamy sand over yellow clay, developed on sandy Tertiary sediments. The colour of the clay B horizon, and the presence of a bleached A2 horizon in the Lawless soils, indicates that they are poorly drained, and that the low permeability of the B horizon restricts downward flow. Therefore, water draining through Lawless cattthment tends to flow through the A horizons into the streams. The differences in stream DOC levels are closely matched by differences in the amount of water soluble carbon in the soils of the catchments, and the water solubility of the soil carbon is in turn negatively correlated with the clay content of the soils. A model of DOC accession in the two catchments is shown in Figure 1. When DOC data from throughout the Mt. Lofty Ranges was examined, it was found that the clay content of soils in catchments could account for a large proportion RETREAT VALLEY

red clay

low permeability

yellow clay

low permeability

Fig. 1 -

Model of DOC accession


of the variation in DOC despite the many other factors which would be involved. It is envisaged that these findings will be widely applicable throughout Australia. Furthermore, soil clay content can be predicted reasonably well from geology. The relationship between stream DOC levels and soil clay content is discussed in more detail in a manuscript which is currently under preparation (Nelson et al., submitted). Although a lot is known about interactions between organic matter and other soil components such as clay (Greenland, 1970; Oades, 1989), and the importance of soils as a source of DOC (Thurman, 1985), this information has generally not been brought together so as to use soil properties to explain variability in water quality. In the case of DOC, it appears that all of the factors governing the retention of organic matter by soils, combined with the factors governing the flow path of water through the soil, are relevant to the quality of water leaving the catchment.

IMPLICATIONS One of the implications for management is that, while in many cases land use and management controls can be used to improve water quality, these sort of controls will not solve the expensive water

D. P. Oliver Continued from page 21 a higher turbidity made up partly of aluminium silicates, which may explain the higher aluminium concentration in Burnside slime. At Burnside the mean copper concentration was approximately two and a half times that at Blair Athol, and almost equivalent to the concentration in slime from the electroplater. The significantly higher copper concentration in Burnside slime may result from the internal plumbing of multi-storey buildings, ie. apartment buildings, which are significantly more abundant at Burnside than at Blair Athol.

CONCLUSIONS This preliminary survey demonstrated that there are very large differences in metal concentrations in slime from different sites. However, biofilm analysis will require further refinement before it can be used as a successful technique for identifying point sources of contamination. Further research is required on the mode of metal uptake by biofilm and factors that may affect uptake. The other factor limiting the usefulness of this technique is the availability of adequate amounts of slime for analysis. Sudden changes in wastewater parameters, such as pH, temperature, chemical composition, volume and velocity of discharge, etc. may cause the biofilm to slough from the sides of the sewer pipe. Thus for the technique to be applied further research would be needed into the conditions that cause biofilm to slough.

ACKNOWLEDGMENTS The author wishes to thank the staff at the EWS State Water Laboratory, Adelaide, and in particular Mr Phil Hine, for his supervision and Messrs John Vanzo and Roger Kennedy for their assistance with the analytical techniques. Also thanks are expressed to Mr Richard Staziak for providing details of survey sites and to EWS personnel who assisted with the field collections. The financial

treatment problems caused by allochthonous, non-point source DOC. No amount of tree-planting, riparian buffer zones, removal of stock or agriculture will help in cases where the soil itself has low adsorption capacity for DOC. Would it be feasible to treat catchment soils to increase their ability to retain organic carbon, or should we continue to solve the problem in our treatment plants? The answers will only be found by continuing to use a multidisclipinary approach to researching and developing solutions to the problems.

REFERENCES Greenland, D.J. (1970). Sorption of Organic Compounds by Clay and Soils. Monograph 37. (Soc. Chem Ind.). Hine, P.T. and Bursill, D.B. (1987). Seasonal trends of natural organics in South Australian waters and their effects on water trea tment. AWRC Research Project 84/ 167, Final Report. Nelson, P.N., Cotsaris, E., Oades, J.M. , Bursill , D.B. and Allen , C . (1990). The influence of soil clay content on dissolved organic matter in stream waters. Aust. J. Freshwater Res. (submitted). Oades, J.M. (1989). An introduction to organic matter in mineral soils. In Dixon, J.B. and Weed, S.B. (eds) Minerals in Soil Environments 2nd Edn. (Soil Science Society of America:Madison). Thurman, E.M. (1985). Organic Geochemistry of Natura l Waters. (Martinus Nijhoft/ Dr.W.Junk Publishers: Dordrecht).

support of the Urban Water Research Association of Australia (UWRAA) is gratefully acknowledged.

REFERENCES Angina, E.E., Magnuson, L.M., Waugh, T.C., et al. (1974). Arsenic in detergents possible danger and pollution hazard. Science 168:389-390. Brown, M.J. and Lester, J.N. (1982). Role of bacterial extracellular polymers in metal uptake in pure bacterial culture and activated sludge. II Effect of mean cell retention time. Water Res. 16: 1549-1560. Eighmy, IT., Maratea, D. and Bishop, P.L., (1983). Electron microscopic examination of wastewater biofilm formation and structural components. Appl.EnvironM icro. Biol. 45 (6): 1921-1931. EWSD, (1978). Safety precautions in sewerage maintenance, Sewerage Division, EWS Dept., EWS 543/ 63. Forstner, U. and Whittman, GJW. (1983). Metal Pollution in the Aquatic Environment, pp.30-48, Springer-Verlag, Heidelberg. Gutekunst, B. and Hahn, H.H. (1985). Heavy metal content in sewer slime - a possibility to detect heavy metal containing discharges into the sewer system. Vom Wasser 65: 127-137. Harris, J.E., Fabris, G.J., Statham P.J. et al ..,1919. Biogeochemistry of selected heavy metals in Western Port, Victoria and use of invertebrates as indicators with emphasis on Mytilus edulis planulatus. Aust.Mar.Freshwater Res. 30: 159-178. Jarrel, K.F. and Sauliner, K.F. (1987). Inhibition of methanogenesis in pure cultures of NH,3, fatty acids and heavy metals, and protection against heavy metal toxicity by sewage sludge. Can.Jour.Microbiol. 33: 551- 554. Klein, L.A., Lang, M., Nash, N. et al. (1974). Sources of metals in New York City wastewater. J. Water Poll.Control Fed. 46(12), 2653-2662. Lester, J.N. (1983). Significance and behaviour of heavy metals in waste water treatment processes I. Sewage treatment and effluent discharge. Sci.Total Environ. 30: I. Lion, L.W. , Schuler, M.L., Hsieh, K.M. and Ghiorse, W.C. (1988). Trace metal interactions with microbial biofilms in natural and engineered systems. CRC Crit. Rev. Environ. Control 17(4): 273-306. Marshall, K.C. (1976). Interfaces in Microbiology, Harvard University Press Cambridge. Metzner, AY. (1977). Removing soluble metals from waste water. Water and Sewage Works 124: 98-101. Pavioni, J.L. (1972). Bacterial exocellular polymers and biological flocculation. J. Water Poll. Control Fed.: 414-431. Rudd, T., Sterritt, R.M . and Lester, J.N. (1984). Complexation of heavy metals by extracellular polymers in the activated sludge process. J. Water Poll. Control Fed. 56(12): 1260-1268. Sokal, R.R. and Rohlf, F.J. (1969). Biometry: the principles and practices of statistics in biological research, pp.198-202; 309-320. W.H. Freeman and Co., San Francisco. Wehr, J.D., Empain, A., Mouvet, C. et al. (1983). Methods for processing aquatic mosses used as monitors for heavy metals. Water Res. 17: 985-992. Wilkinson, J.F. (1958). The extracellular polysaccharides of bacteria. Bacteriol.Rev. 22: 46-71.

BNR-1 BIOLOGICAL NUTRIENT REMOVAL FIRST AUSTRALIAN CONFERENCE 9-12 July Bendigo C.A.E., Vic Information: W.G.C. Raper, CSIRO Private Bag 10, Clayton, 3168 Tel: (03) 542 2244.

INTERNATIONAL SYMPOSIUM ON DEVELOPMENT OF SMALL SCALE WATER RESOURCES IN RURAL AREAS 21-25 May 1990 Khon Kaen, Thailand

Co-organisers: • Carl Duisberg Gesellschaft. • Dept Local Admin , Min of Interior. • Faculty of Engineering , Khon Kaen University. Secretariat (for Registration Forms): SITRA Co Ltd , Bangkok Tel: 662 246 9291 Fax: 662 246 9294

WATER February, 1990

39

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Water Journal February 1990  

Water Journal February 1990