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<br />DESALINATION <br /> <br />Desalination removes salt and other dissolved <br />minerals from water and is one method to reclaim <br />water lor other uses. Desalination plants have <br />treated brackish groundwater, irrigation runoff, <br />sea water and domestic wastewater for decades <br />in California. <br /> <br /> <br />Reverse osmosis is one <br />(~f rhe most advanced - <br />and most expensive- <br />water treatme1ll options <br />available. <br /> <br /> <br />Source: Orange <br />(ountyWaterDistrict <br /> <br />11 <br /> <br />In the mid-1980s, facilities that desalt sea water I <br />for industrial use went on-line and during the <br />1987-1992 drought, desalination was expanded I <br />out of necessity. Desalination, however, is energy <br />intensive and generally more expensive than <br />other water supply options. It generally costs <br />between $900 an acre-foot to $2000 an acre-foot <br />to desalt seawater and $400-$800 to desalt <br />brackish groundwater or other saline water <br />supplies, thus significantly limiting its use. <br /> <br /> <br />There are two desalination processes that use <br />semi-permeable membranes to separate salt and <br />other dissolved minerals from water. One method <br />is reverse osmosis, which forces pressurized <br />saline water through a semi-permeable mem- <br />brane that inhibits the passage of dissolved solids, <br />including salt. The other, electro-dialysis, uses a <br />combination of electrical charges and membranes <br />to extract the salt and separate the treated water <br />into a fresh pool and a brine pool. <br /> <br />The first community in the state to desatt sea <br />water as a drinking water supplement was the <br />city of Avalon on Santa Catalina Island. Two other <br />coastal desalination plants were constructed for <br />municipal use in Santa Barbara and Morro Bay. <br />Water from Santa Barbara's desalination plant <br />costs $2,000 an acre-foot and was used for a <br />couple of months in 1991 and 1992. The plant <br />has a capacity of 7,500 acre-feet a year and <br />produced a total of 420 acre-feet to make up for <br />the shortage of surface supplies during the <br />drought. Currently, the plant is being maintained <br />on long-term stand-by and will be put back <br />on-line if the need arises. <br /> <br />SIZE COMPARISON <br /> <br />If a water molecule ... then a virus <br />were the size of a would be the size <br />tennis ball... of a tractor trailer... <br /> <br />,.J ef.. <br /> <br />... and a bacterium <br />would be the size <br />of Luxor in Las <br /> <br /> <br />vega4 <br />