Treatment of praziquantel wastewater using the integrated process of coagulation and gas membrane absorption

Praziquantel is an anti-schistosoma drug, its wastewater contains numerous cyanide and other colloid pollutant. A novel integrated treatment process was proposed in this study, i.e., using coagulation to eliminate colloid pollutant and using gas membrane absorption (GMA) to remove cyanide. The optimization of coagulation condition, determination of cyanide removal rate, elimination of membrane fouling, and overall evaluation of the integrated process for the treatment of praziquantel wastewater were investigated in this study. Good results were achieved: turbidity reduced from 700 NTU to 10–40 NTU, 92% COD was removed, cyanide concentration dropped from 3500 mg/L to below 0.5 mg/L, recovery rate of cyanide reached to 98%, and operation cost could be entirely compensated from the gain of recovered cyanide. The results demonstrate that the novel integrated process offers a number of advantages over alkaline chlorination method in the treatment of praziquantel wastewater: cyanide can be reused rather than destroyed, no secondary pollutants are produced, the operation cost is low and the equipment etching is avoided.