WATER
m embrane processing tanks, allowing the backpu lse to be gravity fed. Th e purge is eithe r fed to an inde pend e nt ind ustrial water supply reservo ir o r discharged to the Bay. This sys te 111 allows chemi cal cleaning to be red uced to approx i111 ately 4 tim es pe r year. The prima ry m e 111bran e cleaner is c hlorine. C lean ing can be don e in an e 111 pty or a full tank. Empty tank cleanin g offers t he be n efits of usin g full strength clean ing sol ution and generating a lower volu 111e of waste .
System Integrity Membrane in tegrity is verified daily with an au tomated air pressure decay test, an d compro mised fi bers can be observed b y the strea m of bubbles and easily re paired in th e fi eld. Pa rticle cou n te rs co ntin uo usly m onitor the fi ltered water to ensu re integrity o f the syste m at all tim es . ZeeWeed® lm 111ersed Membran es have bee n o perating at th e Colli ngwood site sin ce 1997 in the temporary UF water fi ltration ta nks. Th ese me m branes w e re transported to the perma nent faci lity in 1998 w ith no 111ajor start- u p or op e rating p roblem s to date .
Table 1: Typica l ZeeWeed® Syst em Results Feed Water
Turbidity Color
TOC Fe Mn Giardia Cysts Cryptosporidium Oocysts Virus
100-5 00 NTU 5-200 Pt/Co units 3-30 mg/L > 10 000 µg > 5 000 µg
Treated Wate r
<0.1 NTU < 5 Pt/Co units
*
50-90% removal * < 100 µg < 50 µg > 9 log removal > 9 log removal >2 log removal
* Color and TOC removal is dependent on raw water quality
Conclusion As potable water regulations continue to increase and fres h water sources are furth e r c om p ro m ise d , m e 111bran e tech nologies will be increasingly em ployed by muni cipaliti es co overcom e th ese challenges. O livenha in M unicipal Water District in San Diego have rece ntl y chosen a ZeeWeed® [111111ersed M embran es fo r their new ·107 ML/d drinking water plant, after com parative evaluation b y the US Bureau of R.ecla111ation and a 12 1110 11th trial on site . This proj ect represen ts the largest ultrafiltration con tract awarded in North Ame1ica. A new Zee W eccl® syste 111
will also be built o n N ew Zealand's Waikato R iver to service the city of Auckland. T he plant will initially suppl y -1-5 ML/d w ith future expa nsion to over triple its o riginal size
Authors Mike Stadnyckyj is in C orporate D evelopm e nt for ZENON En viron m en t Inc, Toro n to, O n tario, C anada. Em ail : m stad n yc @ ze n o n e nv. co m. David Oakley is Environmen tal Sa les M anager for !<...oils- R oyce Au st ra lia Ltd w h ich ope rates a li cenc ing agreem e nt with Z E NON E n v iron m e ntal I n c . for Australasia and the P acific.
Engineering Services State Water Projects Queensland Department of Natural Resources
Tel: 07 3224 8311 Fax: 07 3224 8922
A-ovidino award 'Mnnino 'M:rter infrastructure enoineerino and desian. construdioo manaaerrent. survevino and aeotechnical investiaatioo