AWWA WQTC52832

The arsenic Maximum Contaminant Level (MCL) is likely to be loweredto about 5 ug/L; the Toxicity Characteristic Leaching Procedure (TCLP) limit for residuals might also be reduced. Currently, the 5 mg/L TCLP limit is based on a leachate concentration that is 100 times the drinking water MCL--a proportionate decrease would lower that limit to 0.5 mg/L. The problem will be exacerbated by the fact that increasing coagulant doses to remove arsenic from drinking water will bothincrease the concentration of arsenic in the residual, and generate a greater quantity of that residual. A comprehensive evaluation of treatment options for the removal of arsenic from residuals generated by a wide range of treatment processes was conducted. The work was conducted for the US Environmental Protection Agency, and focused on developing a short list of arsenic removal options and preliminary costs for liquid, semi-liquid, and solid residuals produced by ion exchange, membrane processes (reverse osmosis and nanofiltration), activated alumina, and iron removal processes. Treatment techniques evaluated included precipitation (with and without polymer) using ferric chloride and alum, adsorption using activated alumina and an iron-based media, and ion exchange. Includes reference, figures.