Biological phosphate and nitrogen removal in a biofilm sequencing batch reactor

The possibility of joining biological phosphorus and nitrogen removal in a biofilm sequencing batch reactor was studied using an operation strategy with four reaction phases: Anaerobic/Aerobic/Anoxic/Aerobic. A 1,000 liter pilot scale reactor, filled with Pall-Rings as biofilm support was fed with municipal wastewater. After operating the system for 615 days, optimal operation conditions were establish to obtain highest removal rates with a well established microbial community. Adequate cycle and phase duration were established and organic loading values were obtained for different treatment purposes. The system worked successfully obtaining removals of COD, phosphates and ammonia nitrogen of 89 ± 1%, 75 ± 15%, and 87 ± 10%, respectively. The high removal efficiencies of P and N were obtained thanks to the establishing relationship between nitrifying bacteria and phosphate accumulating bacteria.