The Influence of temperature on bioflocculation and settling of activated sludge and their flocculation mechanisms involved.

摘要

Effects of temperature (conventional (25°C) vs. mesophilic (35°C) vs. thermophilic (55°C)) on activated sludge properties (production and composition of EPS and interaction potential) and weir roles in bioflocculation and settling were studied using well-controlled sequencing batch ractors fed with a synthetic wastewater comprised of glucose and inorganic nutrients. The results show that thermophilic sludge had a poorer bioflocculation ability and settleability than that of conventional and mesophilic sludge. Analysis of extracellular polymeric substances (EPS) indicates that thermophilic sludge had a higher level of loosely bound EPS (LB-EPS) content than that of conventional and mesophilic sludge. The LB-EPS content of thermophilic sludge was ten times more than TB-EPS content of it, which coincided with higher supernatant turbidity. Therefore, the worse bioflocculation and settling ability of thermophilic sludge could be explained from the perspective of LB-EPS. Calculating the interaction energy of three kinds of sludge, the interaction barrier of thermophilic sludge disappeared which meant the attractive potential was dominant in the system.