Study on the treatment of acidic arsenic-containing industrial wastewater in nonferrous smelting.

Based on experimental investigations, a two-stage route is proposed for treatment of acid wastewater with high (860 mg/l) arsenic content from a nonferrous metal smelter. The first stage is flocculation with the flocculant PNS and the addition of phosphate as an oxidising agent in which As3+ is oxidised to As5+ and arsenic and heavy metals are removed. The second stage is removal of sulphate and fluoride ion by neutralisation with a mixed alkaline solution to form insoluble fluoride and gypsum. Process variables were optimised using results of laboratory tests. The gypsum is suitable for cement manufacture and the effluent meets relevant Chinese standards for discharge.
Based on experimental investigations, a two-stage route is proposed for treatment of acid wastewater with high (860 mg/l) arsenic content from a nonferrous metal smelter. The first stage is flocculation with the flocculant PNS and the addition of phosphate as an oxidising agent in which As3+ is oxidised to As5+ and arsenic and heavy metals are removed. The second stage is removal of sulphate and fluoride ion by neutralisation with a mixed alkaline solution to form insoluble fluoride and gypsum. Process variables were optimised using results of laboratory tests. The gypsum is suitable for cement manufacture and the effluent meets relevant Chinese standards for discharge.