The Groundwater Replenishment (GWR) System is a joint venture between the Orange
County Water District (OCWD) and the Orange County Sanitation District that will
eventually treat close to 100 million gallons per day (mgd) of municipal effluent using
microfiltration (MF), reverse osmosis (RO), and advanced oxidation (ultraviolet treatment
with hydrogen peroxide). The GWR System will provide 70-mgd of RO permeate for
groundwater recharge and maintenance of an intrusion barrier to protect the local
groundwater basin from seawater infiltration.
OCWD operated Phase 1 of the GWR System between April 2004 and July 2006. Phase
1 included reusing a portion of Water Factory-21 (WF-21), a thirty-year old treatment
facility that consisted of lime clarification and conventional filtration followed by RO. The
existing pipelines, basins, pumps and RO system were reused while a 6.5-mgd MF
system was installed and served as the new pretreatment process for the existing 5-mgd
RO system. The RO trains were upgraded to thin-film composite membranes. Advanced
oxidation was added downstream of the RO process for additional disinfection and
destruction of emerging contaminants. In the summer of 2006, the remaining WF-21
facilities used in Phase 1 were decommissioned. The GWR System will consist of
twenty-eight MF units of 3-mgd capacity each and fifteen RO trains of 5-mgd capacity
each, for a total RO production capacity of 70-mgd.
The interim Phase 1 facility served as a testing ground that allowed the water
productions staff to not only optimize its operations and conduct valuable training but to
improve upon the design of the larger 70-mgd GWR System. Staff identified,
documented, and corrected multiple issues associated with the MF and RO systems. In
conjunction with the MF manufacturer, a number of issues were resolved, including
substandard filtrate quality brought about by membrane integrity, module o-ring
deterioration and hydraulic loading of the filtrate header piping. Improved MF system
performance was immediately evident in the downstream RO performance. The RO
system benefited from decreased feed pressures that translated into direct cost-savings
associated with reduced energy consumption.
A variety of cleaning strategies were tested using the 5-mgd RO and included the use of
generic and proprietary chemicals. OCWD personnel optimized cleaning procedures
and identified the most efficient and cost-effective method for consistently cleaning the
membranes. A new methodology of procuring RO antiscalants (including optimization of
sulfuric acid usage) was also employed. Pilot-scale testing of antiscalant performance
and full-scale application of the lowest cost product resulted in substantial cost-savings. This paper documents the optimizations and improvements made possible by operating
the interim Phase 1 facility during construction of the GWR System. In addition, this
paper outlines projected savings anticipated for each of the findings. Includes tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.3 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 20 |
| Published : | 03/01/2007 |
