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In September 2003, the City of Phoenix commissioned the nation's first full-scalearsenic removal facility for potable water. The U.S. Environmental Protection Agency (USEPA) islowering the maximum contaminant level (MCL) for arsenic from 50 parts per billion (ppb) to 10 ppb effective January2006. In response to this change in the standards, the City decided to build a full-scaleArsenic Treatment Facility (ATF) as a demonstration project and identify operationalissues prior to implementing the technology at the City's 15 well sites that have anarsenic concentration greater than 10 ppb.The demonstration facility was built at Well 280 which has a capacity of 2.5 MGDand contains a 1.0 MG reservoir, sodium hypochlorite generator, and booster pump stationfor pressure zone 9. Due to the water quality and ease in operation, the City chose to implement anadsorption process using granular iron media (GIM). GIM is a throw-away media whichafter exhausted may be hauled to a non-hazardous waste landfill. At the pH range ofWell 280, the process requires no chemical addition other than chlorine to disinfect themedia. The process is fairly simple to operate and includes a pre-filter (50 micronmechanical screen), two 14-foot diameter steel contactors with media, rate of flowcontrol valves, equalization basin, spent media drain area, PLC, and several valves andflowmeters. This paper discusses operational issues from this demonstration project that will result in improvements made to the treatment process. Includes figures.

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Edition: Vol. - No. Published: 06/17/2005 Number of Pages: 6File Size: 1 file , 490 KB