Influence of carbon and alternating oxic-anoxic model on sludge bulking and pollutant removal effect

Abstract

KEYWORD: SBR; Alternating oxic-anoxic; Sludge bulking; Sodium acetate; Pollutant removal ABSTRACT: The influence of carbon and alternating oxic-anoxic model on sludge bulking and chemical oxygen demand (COD), ammonia nitrogen and total nitrogen removal effect are investigated under alternating oxic-anoxic model in sequencing batch reactor (SBR). The experiment performed for 23 days and 30 days instage 1 and 2 separately. The results showed that the average removal rate of ammonia nitrogen,total nitrogen and COD were 97.8%,68.1% and 55.1% in stage 1. The average removal rate of total nitrogen improved to 90.4% in stage 2 mainly due to that the addition of carbon source and more electron accepter, more nitrate and nitrite were reduced to nitrogen, The removal of COD reached 82.5% due to the addition of sodium acetate and the increasement of organic loading, at last the effluent met the national level A standard. The MLSS maintained steadily around 3000mg/L in stage 1 and 2, the SVI improved slowly and reached 180 ml/g at the end during stage 2, the inflow water got high concentration of small molecular compounds by addition of sodium acetate which was favor of increasement of filamentous bacterium, the SVI was affected by the amount of filamentous bacterium.