AWWA MTC69656

The Coastal Water Project is the seawater desalination project currently underway by California American Water (CAW), and the project is in the midst of permitting and conducting a pilot study to obtain the necessary information to support the future design, commissioning, and operation of the full-scale desalination plant. Pilot testing is being conducted on Moss Landing Power Plant (MLPP) property during an approximate twelve-month period which began in 2008. The testing utilizes once-through cooling water from the MLPP cooling water system, which is pumped from Moss Landing Harbor. The projected full-scale desalination facility will utilize the same water source. Results presented in this paper detail the findings of the pilot study pertaining to the pretreatment evaluations. This project is unique among seawater desalination previously or currently conducted in California and the United States as this study combines many facets of treating seawater that had to date only been tested separately. Those facets are: treatment of cooling return water and the effects on pretreatment requirements; evaluation of strictly ultrafiltration (UF) membranes; evaluation of three different UF manufacturers; and, the combination of coagulation/flocculation on the UF and seawater reverse osmosis (SWRO) membrane performance. Includes table, figures.