Eastern Municipal Water District (EMWD) has evaluated candidate technologies for treatment and recovery of
the reject (waste) stream from the ultrafiltration (UF) system at the Perris Water Filtration Plant (PWFP). The
treated water from the reject recovery system will either be combined with reclaimed water or recycled to the
head of the PWFP and processed into potable water. The treated reject flow should have characteristics that are
similar to or better than raw water quality to minimize adverse impacts on UF system operation when the treated
reject water is recycled back to the PWFP (i.e., turbidity <2 NTU and TOC<3 mg/L). Based on project objectives
and constraints, three treatment technologies were short-listed from a total of seven applicable technologies
using non-monetary criteria and a quantitative scoring technique. The short-listed technologies (membrane
filtration, inclined plate settling and ballasted flocculation) were further evaluated via multi-attribute analysis
which identified pressurized membrane filtration as the best option. Ballasted flocculation received a higher
benefit-to-cost ranking than plate settling, however the potential for sand and polymer carryover was deemed to
represent a serious risk to the PWFP UF operation by the membrane supplier, negatively impacting their
membrane warranty. Consequently, ballasted flocculation was eliminated as an implementable reject treatment
alternative. To confirm the benefit of membrane filtration over plate settling, a bench testing was conducted such
that final technology selection was based on empirical data, rather than assumptions. This paper describes the
reject recovery treatment alternative selection and summarizes bench-testing findings. Includes tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 820 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 15 |
| Published : | 11/01/2009 |
