Factors affecting biological removal of phosphorus

A pilot plant study on biological removal of phosphorus was conducted over fifteen months to obtain optimum operational conditions and evaluate process performance. The pilot plant was composed of an anaerobic zone followed by an aerobic zone, and had a capacity of treating 100 m3 municipal wastewater per day. In the anaerobic zone, BOD loading rates and BOD to MLSS ratios were found to be important factors. In the aerobic zone, on the other hand, the hydraulic retention time had a significant influence on the phosphorus removal efficiency. For successful removal of phosphorus, a shorter hydraulic retention time in the aerobic zone along with appropriate parameters in the anaerobic zone (BOD loading rate ≦ 2 kg-BOD/kg-MLSS day, BOD to MLSS ratio ≦ 0.1 kg-BOD/kg-MLSS) are essential.