Disposal of Arsenic-Laden Adsorptive Media: Economic Analysis for California

Abstract

Due to California’s stringent hazardous waste (HW) classification regulations, high-capacity adsorptive media (AM) used for the removal of arsenic from potable water are likely to be classified as HW if operated to breakthrough. An alternative is to prematurely retire the AM, avoiding generation of HW. The impact of waste classification of spent AM on annual costs for arsenic systems was investigated. For a typical small water system (SWS), the media replacement cost alone was predicted to range from $0.80 to $2.00 per 1,000 L treated, in comparison to the average cost of tap water in the U.S. of $0.53 per 1,000 L treated, highlighting the financial burden for SWS. The costs of media replacement dominated over costs for transport and disposal regardless of whether spent media were designated as HW or non-HW. Media costs and influent arsenic concentration were more significant factors than transport distance or disposal fees. Under typical conditions for SWS, it was found to be cost effective to load the media to exhaustion as long as the arsenic loading at replacement was greater than 560-mg arsenic/kg AM, a situation readily obtained with commercially available high-capacity iron oxide adsorbents.