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This paper evaluated a new material, water treatment residual solids (WTRSs), as anarsenic adsorbent through batch adsorption and column experiments. By reusing WTRSswithin the water industry, the water industry will reduce the overall consumption ofchemicals used for treatment, and reduce the amount of waste generated from treatmentprocesses. This work examined arsenic adsorption on four types of WTRSs, and compared thisperformance to arsenic adsorption with a proven adsorbent, granular ferric hydroxide(GFH). WTRSs were collected from four water treatment plants in the United States andCanada (Plant 1 to Plant 4). The treatment plants were carefully selected in order toobtain residuals with diverse compositions. WTRSs were received at DalhousieUniversity as a wet residual (typically 10-30 % solids) and were oven dried at 105 C andair dried in a desiccator. Plant 1 used ferric sulphate as a coagulant, Plant 2 used lime as asoftening product, and the other two plants used alum coagulants. Among the alumplants, Plant 3 was a river source with a raw water alkalinity of 150-200 mg/L whereasPlant 4 was a lake source with an alkalinity of less than 5 mg/L. Thus this researchcompared the impact of coagulant type on arsenic removal, using the results of the batchand column experiments and an analysis of the residual solid chemistry.Adsorption experiments were conducted in three phases:Phase 1 used batch adsorption experiments with As-spiked deionized water todetermine adsorption isotherms for WTRSs and GFH;Phase 2 used column adsorption experiments with synthetic water using an alum andferric residual; and,Phase 3 used column adsorption experiments with two groundwaters from Nova Scotiausing an alum and ferric residual. Includes 11 references.

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Edition: Vol. - No. Published: 11/01/2006 Number of Pages: 6File Size: 1 file , 340 KB