Pilot study on treatment and near zero discharge of gallium arsenide wafer processing wastewater

In the process of gallium arsenide wafer, a large number of toxic and harmful organic wastewater with arsenic was produced. In this paper, the process of “arsenic removal pretreatment+biochemical treatment+advanced treatment” was used to achieve the standard treatment of gallium arsenide wafer processing wastewater and near-zero discharge. The arsenic removal was achieved by the pretreatment process of “two-stage coagulation+ion exchange resin”. The arsenic removal rate reached more than (99.998±0.003)%, and the arsenic content in the effluent reached the discharge standard. Biochemical treatment adopted the process of “O3 oxidation+hydrolytic acidification+biological contact oxidation”, the COD removal rate was (95.7±0.3)%, and the effluent could meet local emission standards. The advanced treatment adopted “ultrafiltration+two-stage reverse osmosis+triple-effect evaporation and crystallization” to realize the reuse of wastewater and resource recovery. By calculation, the cost of treating arsenic-containing organic wastewater was about 36.11 yuan/m3. This pilot study verified the feasibility of resource recovery and near-zero discharge of gallium arsenide wafer processing wastewater, and provided reliable and effective technical support for the standard discharge, resource recovery and utilization of arsenic-containing wastewater in the industry.