Simultaneous nitrogen and phosphorus removal by immobilized bacterial particles of denitrifying phosphorus accumulating microorganisms and its application

Abstract

Enterobacter cloacae G, a novel denitrifying phosphorus-accumulating bacterial strain, was isolated from anaerobic sludge tank of a wastewater treatment plant used for pig farms. It was discovered that a pH of 7, a temperature of 30°C, an initial phosphorus concentration of 8 mg/L, and a C/N ratio of 10 were the strain's ideal growth conditions. To ensure the stability of strain G in wastewater treatment, strain G was immobilized by 5 % polyvinyl alcohol, 2 % sodium alginate, and 0.6 g of biochar and crosslinked for 9 h in 4 % calcium chloride saturated boric acid solution via an orthogonal test. After the immobilized microspheres were introduced into the sequencing batch reactor (SBR), the nitrate and phosphate removal rates achieved were 89.36 % and 65.53 %, respectively, with a hydraulic retention time (HRT) of 8 hours, a pH of 7.5, and a C/N ratio of 4.5. The immobilized microspheres containing strain G demonstrated potential for the treatment of nitrogen-rich and phosphorus-rich wastewater.