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Following nine months of Phase I demonstration testing of the non-biological application ofmicrofiltration (MF) on primary effluent as part of the Integrated Membrane AnaerobicStabilization (IMANS) treatment concept, Phase II of the project was continued at the OrangeCounty Sanitation District (OCSD) starting in October 2002. Phase I work had shown that theMF was capable of treating primary effluent economically in a non-biological treatment step fordirect ocean discharge. Quality of the discharge effluent from OCSD'S two large treatmentplants, each with a capacity of around 150 mgd, along with management of peak flows, are themajor concerns for the District. While OCSD has two ocean outfalls to discharge treatedwastewater, the shorter of the two is currently only permitted for emergency discharges becauseit discharges closer to the shoreline and would require a significantly higher quality effluent.Regular use of the "short" ocean outfall could save the District millions of dollars by delayingthe need to build another deep-water outfall. To meet the needs for higher quality effluent, nonbiologicalmicrofiltration of primary effluent is one alternative that the District is considering.Phase I of the demonstration work was performed from January to September 2002. The projectwas extended into a second phase following the success of Phase I testing.As during Phase I, excellent water quality was observed with 3 to 4-log removals for total andfecal coliforms and about 2-log removal for coliphage virus achieved during the first six monthsof testing done in Phase II. Some of the operating parameters for the plant were modified tooptimize performance following increasing suspended solids loads on the membranes. Thesechanges, including experiments with lower fluxes and more frequent backwashes, were alsomade to account for inefficient chemical cleaning of membranes resulting from problems withthe cleaning solution heating equipment. However, no signs of irreversible membrane foulingwere observed in this period.Phase II of the demonstration testing continued from October 2002 through January 2004.Results obtained from October 2002 through March 2003 are discussed in this paper. Based onthese results, it is concluded that MF technology still remains more cost efficient and producesbetter quality effluent than secondary treatment followed by disinfection. Includes 2 references, figures.

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Edition: Vol. - No. Published: 06/17/2004 Number of Pages: 11File Size: 1 file , 440 KB