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~<,;;..; " ~",' '.7 ~. '-, ";; ,...--_..~. . ~} "'.. ,:",.",:":" EXECUTIVE SUMMARY This report presents the results of Task 3 of Bureau of Reclamation Contract 4-~-81-03600 which evaluated water treatment process optIons applicable to the use of Palo Verde Irrigation Outfall Drain as a water supply for a W hypothetical coel-flred power plant located In the Mojave Desert between ~ Blythe. California and Las Vegas. Nevada. The TaSk 3 study was performed conjunctIon with a field test of Ion exchange softening technology conduct at the Etiwanda Generating Station near San Bernardino. California. Deta"'-l from the field test program were used to support the design and cost evalua- tions of Ion exchange softening technology In the study. The comparison of water treatment process options was based on a two-unIt coal-fIred powerplant with 600 megawetts of total net generating capacity. The reference powerplent assumed Cal Itornla regulatory criteria. and Included the use of wet limestone scrubbers for sulfur dioxIde control and zero dis- charge of liquId wastes. The Palo Verde Irrigation Outfall Drain water supply was chosen because of the avallab Illty of a comp I ete water qua I lty data base. an adequate quantity for a 600 megawatt powerplant and because the water quality was suitable for evaluation of Ion exchange softening technology for cooling water makeup treatment. Five water treatment process options. were developed for technical end economic comparisons. These options Included: Ion exchange softening of cooling tower makeup, sldestream caustic/soda softening of the circulating water system. vapor com- pression evaporators for wastewater concentration and reuse. and evaporation ponds for flnel wastewater disposal II Sldestream lime/soda softening of the circulating water system, vapor compression evaporators for wastewater concentretlon and reuse. and evaporation ponds for final wastewater disposal III No makeup or sldestream treatment of cooling water, no evaporators for wastewater concentration and reuse. and evaporations ponds only tor wastewater disposal IV No makeup or sldestream treatment of cooling water. vapor compres- sion evaporators for wastewater concentration and reuse. and evaporation ponds for final wastewater disposal V Makeup lime/SOda softenIng for cooling water 1Teatment. vapor com- pressIon eveporators for wastewater concentration and reuse, end evaporation ponds for tlnal wastewater disposal Date from the Etlwande Field Test Program were used to supplement the design of the Ion exchange softenIng system. The Etlwanda field test results showed that Ion exchange softening, using cooling tower blowdown for regeneration. was technically vIable for both fluidized bed upflaw regeneration and for rapid downflow regenerctlon. The process design tor Option I used the more conservative upflow confIguration. v