AWWA WQTC62547

Rapid Small Scale Column Tests (RSSCTs) were used as a timely means to quickly verify Arsenic technology selection for a specific water matrix and to develop associated cost projections for three municipalities in Arizona as part of their efforts to gain compliance with the new 10 µg/L Arsenic maximum contaminant level. RSSCTs were conducted using three to five commercially available media on six groundwaters in Arizona. Testing was done following a protocol developed by Arizona State University. RSSCTs were originally developed to quickly evaluate the organic removal performance of activated carbon, and similar protocols have been developed for Arsenic removal with metal-oxide sorbents. The results from the RSSCTs allowed comparison of run lengths (measured in bed volumes (BVs)) from each media before the Arsenic concentration in treated water was greater than 10 µg/L or a specified target goal. These tests simulate operation of a full-scale Arsenic adsorption treatment system. Due to the rapidly approaching implementation of the Arsenic rule, several municipalities have been working to expedite Arsenic treatment system selection and implementation. RSSCT durations range from 2 to 8 weeks rather than 6-months to 12-months required for pilot testing. RSSCTs were used at different groundwater wells to confirm the effectiveness of adsorption media for Arsenic removal in specific water matrices. Groundwater tested covered a range of water quality parameters. Arsenic concentrations ranged from 11 to 50 µg/L. Field pH ranged from 7.5 to 8.6. Silica concentrations ranged from 15.4 to 47.6 mg/L. In some cases Arsenic breakthrough curves showed notable differences based upon differing water matrices and in other cases media performance was similar. Based upon a fast approaching compliance deadline, bench scale testing using RSSCTs was specified by each of three water systems in lieu of pilot testing. RSSCTs were not only utilized to ensure that the media selected adequately removed Arsenic, but testing was also used to prescreen vendors for bidding purposes and help establish anticipated media change-out frequencies and associated operation and maintenance cost projections. This paper will benefit water systems that have struggled to meet compliance by January 2006, with the introduction of a tool that will aid in making secure decisions on technology selection. RSSCTs may also be used in forthcoming years to test new media on specific water matrices as they become available on the market. Includes tables, figures.