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DANIEL C. M. CRABBE due to evaporation and to fertilizers dissolving into the water. The land in lower regions can even be- come swampy. California's solution is to construct a master drain which is known as the San Joaquin Drain, Upon completion in 1970, this canal will stretch almost 250 miles from Bakersfield to San Francisco Bay. Many farmers have already sunk drain pipes under their fields to carry this water away. The creation of this tremendous drainage canal will solve the problems of salt buildup and satu- rated farm land. However, the disposition of this waste water is another problem. Besides the drain water being unusable due to the high salt content, the large nutrient loading will create an algae growth in San Francisco Bay. Consequently, the designers of this project are faced with either pumping the 590 )uillion gallons of waste water per day over the mountain into the Pacific Ocean or removing the nutrient from the water. Many methods are presently being investigated to make this drain water acceptable for dispo- sal in San Francisco Bay. A biological process seems likely to be adopted initially; but with the great need for additional fresh water in the valleys, desalination of this waste stream by reverse osmosis may be the most economical solution. , (SLIDE 13) Test results presented here show feed water containing around 6000 ppm of total dissolved solids being reduced to 400 ppm. The only pretreatment of this feed water was acidification to lower the pH, which has been found to improve the rejection capabilities of our membrane barrier, Besides the reduction of the nitrate ion in this test we have since discovered that a significant boron reduction can be obtained if the alkalinity of the feed water is raised to a pH of 10. At this point, the boron is ionized and rejected by the membrane. A second area of waste water reclamation field testing is presently being done at the Ventura, California Sanitation Department Sewage Treatment Plant. Ventura, located approximately 60 miles north of Los Angeles, was selected as a test site because of the interest shown by city officials in wat- er reclamation and reuse, and the advanced methods of sewage treatment employed at this plant. Ventura is rapidly outgrowing the available water and that which they are presently using con- tains an amount of dissolved material greater than that recommended by the United States Public Health Service. Ventura's growth rate is presently decreasing and the need to obtain more and better water to attract new industry is apparent. Waste water reclamation with reverse osmosis would create not only a new source of water, but a better water supply to attract these industries. (SLIDE 14) In late August, a Du Pont 4" permeator and pilot plant were installed at Ventura along with a feed tank, rapid sand filter and other pretreatment equipment. The main purpose of this test is to de- termine the minimum pretreatment requirements and establish operating conditions for long-term test- ing. . (SLIDE 15) In our initial test, sewage effluent was taken directly from a high rate trickling filter, treated with a chemical coagulant and passed through a sand filter. The water was then passed through an activated carbon column and two small cartridge filters into a feed tank where sulfuric acid was added. to lower the pH for improved separation performance. (SLIDE 16) An analysis of the water after permeation shows that a product water containing less than 300 parts per million of total dissolved solids was produced, again, well below the Public Health Service re- commendations for drinking water. The water produced by the reverse osmosis unit was not only clear in appearance compared to the feed water, but, according to some personnel at this location, tasted better than the present muni- cipal water supply. -13-