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 costprojections for three municipalities in Arizona as part of their efforts to gain compliance with thenew 10 µg/L Arsenic maximum contaminant level. RSSCTs were conducted using three to fivecommercially available media on six groundwaters in Arizona. Testing was done following aprotocol developed by Arizona State University. RSSCTs were originally developed to quicklyevaluate the organic removal performance of activated carbon, and similar protocols have beendeveloped for Arsenic removal with metal-oxide sorbents. The results from the RSSCTs allowedcomparison of run lengths (measured in bed volumes (BVs)) from each media before the Arsenicconcentration in treated water was greater than 10 µg/L or a specified target goal. These testssimulate operation of a full-scale Arsenic adsorption treatment system.Due to the rapidly approaching implementation of the Arsenic rule, several municipalities havebeen working to expedite Arsenic treatment system selection and implementation. RSSCTdurations 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 adsorptionmedia for Arsenic removal in specific water matrices. Groundwater tested covered a range ofwater quality parameters. Arsenic concentrations ranged from 11 to 50 µg/L. Field pH rangedfrom 7.5 to 8.6. Silica concentrations ranged from 15.4 to 47.6 mg/L. In some cases Arsenicbreakthrough curves showed notable differences based upon differing water matrices and inother cases media performance was similar.Based upon a fast approaching compliance deadline, bench scale testing using RSSCTs wasspecified by each of three water systems in lieu of pilot testing. RSSCTs were not only utilizedto ensure that the media selected adequately removed Arsenic, but testing was also used toprescreen vendors for bidding purposes and help establish anticipated media change-outfrequencies and associated operation and maintenance cost projections. This paper will benefitwater systems that have struggled to meet compliance by January 2006, with the introduction ofa tool that will aid in making secure decisions on technology selection. RSSCTs may also beused in forthcoming years to test new media on specific water matrices as they become availableon the market. Includes tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2005

Number of Pages:

11

File Size:

1 file , 330 KB