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Carlsbad Municipal Water District (CMWD) is planning to build the new Carlsbad Water Recycling Facility (CWRF) as part of a comprehensive regional program to increase water reuse efficiencies and enhance local reliability. The new 4 million gallon per day (mgd) CWRF will be adjacent to the Encina Water Pollution Control Facility (EWPCF). The new CWRF will take secondary effluent from the EWPCF and produce recycled water meeting Title 22 of the California Administrative Code for unrestricted nonpotable reuse. This paper presents key highlights from the preliminary design investigation and describes the recommended project. The recommended treatment plan is the parallel use of the DynaSand continuous backwash granular media filter system with either the US Filter/Memcor or Pall MF system, or the Zenon UF system. MF/UF will be followed by reverse osmosis (RO). Based on an influent TDS concentration of 1,400 mg/L, approximately 1.4 mgd of MF/UF and RO treatment will be required to provide blended water with a maximum TDS concentration of 1,000 mg/L. The evaluation of disinfection alternatives consistently resulted in sodium hypochlorite as the overall highest ranking disinfection alternative. However, as design transmittance levels were increased from 55 percent to 70 percent, a value likely to be achieved at the new CWRF, the life cycle cost for low-pressure/high-intensity UV was lower than that for sodium hypochlorite. As such, low-pressure/high-intensity UV should also be considered during final design. Includes tables, figure.

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Edition: Vol. - No. Published: 01/01/2002 Number of Pages: 20File Size: 1 file , 470 KB