Novel multiple coagulant from Bayer red mud for oily sewage treatment

摘要

Multiple coagulants for the treatment of wastewater were prepared. To obtain the optimum synthetic conditions of coagulants, response surface methodology was used to establish the relationship between parameters and the treatment efficiency. In addition, parameters affecting the coagulation–flocculation process, such as the dosage of attapulgite (ATP), the dosage of poly-dimethyl-diallyl-ammonium chloride (PDMDAAC), and the reaction temperature, were investigated. The optimized parameters to prepare multiple coagulant were determined as the dosage of ATP and PDMDAAC being 4 and 2%, respectively, and the reaction temperature being 60°C. The coagulation performance for oily sewage showed that the optimum dosage of coagulant for the maximum treatment was 100 mg/L and the sedimentation time was 30 min at 60°C. In the coagulation–flocculation process, the COD of the oily water decreased from 534 to 246 mg/L and its turbidity decreased from 124 to 2.0 NTU.