Evaluation of phosphorus removal from wastewater by chemical precipitation agent - A case study of Jingzhou City Moat

Phosphorus removal from wastewater is of extraordinary importance. In the present research, ferric chloride, calcium hydroxide, calcium chloride and ferric sulfate were selected to develop the best precipitation for phosphorus removal from the heavy polluted wastewater in Jingzhou City Moat. Orthogonal experiment of three elements and three levels was also conducted to investigate the optimum removal conditions. The laboratory results showed that, taking into account of removal efficiency and effluent pH, ferric chloride which achieved a removal rate of up to 97% and an available effluent pH of 7 was considered to be the optimal precipitation. Results of orthogonal experiment showed that, different from the contact time, the dosage and pH of aqueous solution were the key factors affecting removal efficiency of ferric chloride. Further investigation was carried out upon combined treatment experiment, as the ratio of ferric chloride to aluminum sulfate was three, the removal efficiency was achieved o be 98%. Results of this study indicated that it was a low-cost, high-efficiency and effective way to remove the excess phosphorus using ferric chloride. And the advantages of combined treatment promised a potential and worthy of study way to phosphorus removal in the future. © 2011 IEEE.