Arsenic removal from high-arsenic water by enhanced coagulation with ferric ions and coarse calcite

• Published in: Water research (Oxford) Vol. 40; no. 2; pp. 364 - 372
• Main Authors: Song, S., Lopez-Valdivieso, A., Hernandez-Campos, D.J., Peng, C., Monroy-Fernandez, M.G., Razo-Soto, I.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2006; Elsevier Science
• Subjects: Applied sciences; Arsenic - chemistry; Arsenic - isolation & purification; Arsenic removal; calcite; Calcium Carbonate - chemistry; Coagulation; Coarse calcite; colloidal properties; Colloidal stability; Exact sciences and technology; extraction; Ferric sulfate; Filtration; Industrial wastewaters; iron; Iron - chemistry; mine spoil; Mining; Pollution; wastewater treatment; Wastewaters; Water Pollutants - isolation & purification; water pollution; Water Purification - methods; Water treatment and pollution; Mexico; Central America; America; Arsenic removal; Coarse calcite; Ferric sulfate; Colloidal stability; Coagulation; Filtration; Arsenic; Calcite; Membrane separation; Microfiltration; Iron III; Coagulation Arsenic removal Coarse calcite Ferric sulfate Colloidal stability; Industrial waste water; Flocculation; Calcium carbonate; Physicochemical purification; Waste water purification; Acid mine drainage; Performance; Mining industry
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2005.09.046

Arsenic removal from high-arsenic water in a mine drainage system has been studied through an enhanced coagulation process with ferric ions and coarse calcite (38–74
μm) in this work. The experimental results have shown that arsenic-borne coagulates produced by coagulation with ferric ions alone were very fine, so micro-filtration (membrane as filter medium) was needed to remove the coagulates from water. In the presence of coarse calcite, small arsenic-borne coagulates coated on coarse calcite surfaces, leading the settling rate of the coagulates to considerably increase. The enhanced coagulation followed by conventional filtration (filter paper as filter medium) achieved a very high arsenic removal (over 99%) from high-arsenic water (5
mg/l arsenic concentration), producing a cleaned water with the residual arsenic concentration of 13
μg/l. It has been found that the mechanism by which coarse calcite enhanced the coagulation of high-arsenic water might be due to attractive electrical double layer interaction between small arsenic-borne coagulates and calcite particles, which leads to non-existence of a potential energy barrier between the heterogeneous particles.