Orange County Water District (OCWD) began operation of Water Factory 21 in Fountain
Valley, California in 1976, which uses a three stage pretreatment process ahead of reverse osmosis (RO)
to reclaim secondary effluent from the Orange County Sanitation District. Now that
Water Factory 21 is nearing the end of its useful life, OCWD is planning the
Groundwater Replenishment (GWR) System as its replacement. The GWR System will
use microfiltration (MF) as pretreatment to RO followed by Ultraviolet (UV) Irradiation.
As part of the project, OCWD has been testing thin film composite RO membranes to
qualify them for the GWR System, which will have a RO capacity of 70 mgd.
Additionally, OCWD has tested low fouling membranes to determine if they would offer
additional benefits to the project.
West Basin Municipal Water District (WBMWD), similar to OCWD, has been in the
forefront of reclamation having installed a conventional pretreatment system including
lime clarification, recarbonation and filtration ahead of RO in 1995 for supplementing the
seawater intrusion barrier. Subsequent to that, WBMWD was the first agency to install
full-scale MF and RO facilities for treating secondary wastewater effluent for injection
into the seawater intrusion barrier at the West Basin Water Recycling Plant in El
Segundo, CA in July 1997. Since that time, WBMWD has continued to expand their
water reclamation and recycling facilities and have installed three additional MF/RO
systems with a combined capacity of approximately 25 mgd. Since the installation of
the existing MF/RO systems, WBMWD has continued to perform additional RO
membrane pilot tests to determine the operating parameters and characteristics of the
membranes. WBMWD is continually looking for the next membranes that will offer
lower operating costs with better salt rejection.
Both agencies recently conducted independent studies to determine if the latest RO
membranes to hit the market, which claimed to be low fouling or fouling resistant
membranes, actually achieved better operating characteristics and lower operating
pressures than previous thin film composite membranes. In 2001-2002, OCWD tested
three low fouling membranes on microfiltered secondary effluent from Orange County
Sanitation District. In 2001-2002, WBMWD under a research grant, operated two
different low fouling membranes in parallel for a period of seven months; and compared
the performance of these membranes with regular thin film composite membranes on
full-scale MF/RO facilities.
This paper focuses on OCWD and WBMWD and why both agencies continue to pilot
test RO membranes before and after their projects are completed. The paper
addresses the results of the testing from both agencies, which have shown that the low
fouling membranes did not operate at lower operating pressure than the previous
membranes. Additionally, the paper focuses on the differences in the fouling
characteristics of RO membranes for two different wastewater sources. Includes 2 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 430 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 18 |
| Published : | 03/05/2003 |
