Treatment of high arsenic content wastewater by a combined physical-chemical process

The performance of a novel combined process, consisting of pre-oxidation, co-precipitation, adsorption and coagulation was investigated for treatment of high arsenic content industrial wastewater. KMnO4 was used to oxidize As(III) to As(V) firstly, meanwhile the total arsenic concentration reduced about 9%. Then lime and ferrous co-precipitation was performed and the arsenic concentration decreased dramatically from 423 mg/L to 6.8 mg/L. Subsequent ferric and manganese binary oxide (FMBO) adsorption and polyaluminum chloride (PACI) coagulation process as a final treatment removed over 99.88% of the residual arsenic. About 5000 m(3) of industrial wastewater, with average arsenic concentration of 465 mg/L, was safe treated and disposed by a combined pilot-scale system. The average effluent concentration of the system was 0.008 mg/L which meet the discharge limit of 0.05 mg/L, and the total removal efficiency was 99.998%. The pilot-scale results indicated that the combined process would be advantageous and practical in treating of high arsenic content wastewater, especially in treating emergency accident of arsenic pollution. (C) 2010 Elsevier B.V. All rights reserved.