Technologies and Costs for Removal of Arsenic From Drinking Water
Technologies and Costs for Removal of Arsenic From Drinking Water
Technologies and Costs for Removal of Arsenic From Drinking Water
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L<strong>and</strong>fill disposal requires that residuals be in a solid <strong>for</strong>m <strong>and</strong> contain no free liquids(typically determined by the Paint Filter Liquids Test, SW-846, Method 9095). Sanitary l<strong>and</strong>filldisposal also requires that sludges meet specific criteria that determine if a waste is hazardous. 40CFR 261 establishes four characteristics <strong>of</strong> hazardous waste: flammability, corrosivity, reactivity <strong>and</strong>toxicity. A waste meeting even one <strong>of</strong> these criteria is considered hazardous. For drinking watertreatment residuals containing arsenic, toxicity is the primary characteristic <strong>of</strong> concern.EPA has established an analytical method, the Toxicity Characteristic Leaching Procedure(TCLP), to measure the toxicity <strong>of</strong> a waste. The current toxicity characteristic (TC) regulatory level<strong>for</strong> arsenic is 5 mg/L, which is 100 times the interim primary drinking water maximum contaminantlimit (MCL) <strong>of</strong> 50 Fg/L. The TC regulatory levels <strong>for</strong> other inorganic contaminants were also basedon 100 times their interim primary drinking water MCL. The MCLs <strong>for</strong> many <strong>of</strong> these inorganiccontaminants have been revised since 1990 whereas the TC levels have not changed. Thus, loweringthe arsenic MCL does not mean that the TC regulatory level will be lowered. A separate rulemakingwould be required <strong>for</strong> the reduction <strong>of</strong> the TC level.Many water treatment facilities currently dispose <strong>of</strong> their waste residuals in commercial orpublic l<strong>and</strong>fills (DPRA, 1993a). In some parts <strong>of</strong> the country, decreasing l<strong>and</strong>fill availability, risingcosts, <strong>and</strong> increasing regulations are making l<strong>and</strong>fill disposal more expensive. As a result, thebenefits <strong>of</strong> mon<strong>of</strong>ills are being discussed within the industry. <strong>Costs</strong> associated with development <strong>of</strong>mon<strong>of</strong>ills are generally less than those associated with the development <strong>of</strong> a sanitary l<strong>and</strong>fill (DPRA,1993a). Mon<strong>of</strong>ills control the type <strong>of</strong> waste that they accept more strictly <strong>and</strong> also limit potentialfuture liabilities. However, it is unlikely that mon<strong>of</strong>ills will be utilized <strong>for</strong> arsenic treatmentresiduals.4.3.5 Hazardous Waste L<strong>and</strong>fill Disposal<strong>Water</strong> treatment residuals containing arsenic which fail the TCLP test <strong>for</strong> toxicity must bedisposed <strong>of</strong> in a designated <strong>and</strong> licensed hazardous waste l<strong>and</strong>fill. Hazardous waste l<strong>and</strong>fills areregulated by the federal government under authority <strong>of</strong> RCRA or by individual states who havereceived authorization under RCRA. Hazardous waste l<strong>and</strong>fills are required to be permitted inaccordance with 40 CFR 270 which specifies l<strong>and</strong>fill construction <strong>and</strong> operation criteria, <strong>and</strong> aredesigned to isolate hazardous contaminants from the environment.The primary limitation affecting the disposal <strong>of</strong> arsenic-containing residuals in a hazardouswaste l<strong>and</strong>fill is the presence <strong>of</strong> free liquids. If any water treatment sludge contains free liquids,4-10
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