Effect of temperature on intracellular phosphorus absorption and extra-cellular phosphorus removal in EBPR process

This study investigated the temperature influence on intracellular absorption and extra-cellular phosphorus removal by extra-cellular polymeric substance (EPS) in enhanced biological phosphorus removal (EBPR) process. Three sequencing batch reactors (SBRs) were operated in anaerobic/aerobic sequence at 5.0, 15.0 and 25.0 °C. Phosphorus removed by intracellular absorption was demonstrated as the dominant part (>80%) in total phosphorus removal operated under different temperatures and the highest total phosphorus removal rate of 95% was obtained due to the highest intracellular phosphorus absorption of 18.2 mg P in a typical cycle at 15.0 °C. Phosphorus removed by EPS removal achieved the highest value at 5.0 °C (2.4 mg P/cycle), which resulted in a higher total phosphorus removal rate at 5.0 °C (90%) than that at 25.0 °C (83%). Low temperature was propitious to EPS phosphorus removal, accounting for 13% of total phosphorus removal at 5.0 °C, which could be mainly due to magnesium phosphate precipitation.