The Olivenhain Municipal Water District (Encinitas, CA) pioneered using ultrafiltration
(UF) membranes for the treatment of drinking water. The Olivenhain Water Treatment Plant
(OWTP), which began operation in 2002, utilizes immersed ultrafiltration (UF) to produce up to 34 mgd of
finished water from the treatment of blends of State Project and Colorado River water, both
characterized by low and consistent levels of total organic carbon (TOC) and turbidity.
In 2006, the District began evaluating an expansion of the OWTP, in response to projected
population growth and increasing water demand. The District also faced the potential
introduction of a new source water, Lake Hodges, into Olivenhain Reservoir. Lake Hodges
water presents a significant change in water quality and new challenges for treatment,
including higher levels of TOC, taste and odor (T&O), iron and manganese, and disinfection
byproduct (DBP) formation. The existing OWTP, which utilizes UF and chloramination
disinfection for treatment, is not equipped to adequately address these water quality
challenges.
The District's objective was to identify the optimum approach for expanding the OWTP,
including addressing water quality changes from Lake Hodges, while continuing to use the
existing UF system. The evaluation considered 26 water treatment alternatives including
membrane pre-treatment, UF, membrane post-treatment, and residuals handling and
disposal, with an emphasis on effective control of organics and taste and odors and on
achieving a sustainable membrane flux and cleaning frequency interval, despite variations
in anticipated source water quality.
Laboratory-scale treatability testing was conducted in support of the evaluation of treatment
approaches to fill specific identified data gaps as part of the decision process. Prior to
testing, a wide range of candidate treatment approaches were evaluated, and ozone and
powdered activated carbon (PAC) were identified as key unit processes for the best
potential approaches to meet the District's treatment goals. The focus of the treatability
testing was on ozone and PAC, and the treatment implications with respect to a number of
specific water quality and cost performance issues. The focused laboratory-scale testing
served as an efficient way to generate key data, understand the effectiveness of potential
treatment approaches, and develop design criteria for potential project implementation. Includes 3 references, table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 810 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 14 |
| Published : | 11/01/2007 |
