AWWA MTC69786

Eastern Municipal Water District (EMWD) has evaluated candidate technologies for treatment and recovery ofthe reject (waste) stream from the ultrafiltration (UF) system at the Perris Water Filtration Plant (PWFP). Thetreated water from the reject recovery system will either be combined with reclaimed water or recycled to thehead of the PWFP and processed into potable water. The treated reject flow should have characteristics that aresimilar to or better than raw water quality to minimize adverse impacts on UF system operation when the treatedreject water is recycled back to the PWFP (i.e., turbidity <2 NTU and TOC<3 mg/L). Based on project objectivesand constraints, three treatment technologies were short-listed from a total of seven applicable technologiesusing non-monetary criteria and a quantitative scoring technique. The short-listed technologies (membranefiltration, inclined plate settling and ballasted flocculation) were further evaluated via multi-attribute analysiswhich identified pressurized membrane filtration as the best option. Ballasted flocculation received a higherbenefit-to-cost ranking than plate settling, however the potential for sand and polymer carryover was deemed torepresent a serious risk to the PWFP UF operation by the membrane supplier, negatively impacting theirmembrane warranty. Consequently, ballasted flocculation was eliminated as an implementable reject treatmentalternative. To confirm the benefit of membrane filtration over plate settling, a bench testing was conducted suchthat final technology selection was based on empirical data, rather than assumptions. This paper describes thereject recovery treatment alternative selection and summarizes bench-testing findings. Includes tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2009

Number of Pages:

15

File Size:

1 file , 820 KB