Removal of phosphorus and nickel from an automobile wastewater by coagulation/flocculation combined with magnetite

Abstract

The method of coagulation/flocculation combined with magnetite powder was used to remove total phosphorus (TP) and nickel from an automobile wastewater. In the method, magnetite powder, poly-aluminum chloride (PAC) and cationic polyacrylamide (PAM) were added into the wastewater. Through a factorial design evaluation, the dosage of PAC was considered as the main factor influencing the TP removal. With a PAC dosage of 0.5 g/L and initial wastewater pH of 10.03, TP removal efficiency reached 96.6% using the method of coagulation/flocculation. When initial pH of the wastewater was adjusted to 10.03, nickel removal efficiency reached 98.0%. Therefore, coagulation/flocculation in relatively high pH (10.03) could effectively remove phosphorus and nickel synchronously. The sludge settling velocity reduced greatly in the beginning of settlement and reached zero after 17 min with magnetite dosage of 2 g/L. The dosage of magnetite powder could enhance the solid-liquid separation in the coagulation/flocculation method. © 2013. The authors.