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 (PACl) coagulation process as a final treatment removed over 99.88% of the residual arsenic. About 5000 m3 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.