[Effects of temperature on combined process of ABR and MBR for domestic sewage treatment and analysis of microbial community].

Effects of temperature on the combined process of ABR and MBR ( CAMBR) for domestic sewage treatment were investigated and the changes in the bacterial community structure were analyzed by PCR-DGGE technique. The HRT, recycle ratio 1, recycle ratio 2, pH and DO were 7.5 h, 200% , 50%, 6.5~8.5 and 3 mg.L-1, respectively. The temperature were controlled at three gradients: middle (25°C ±5°C ), low (10°C±5°C) and high (35°C±5°C ). The results showed that the change of temperature had little influence on COD removal, and the CAMBR in stable state showed good performance in COD removal. In addition, the CAMBR achieved good effluent quality in middle or high temperature environment, and the average TN removal efficiency was 70% with an effluent TN of 9 mg L-1, and the average TP removal efficiency was 73% with the effluent TP below 0. 8 mg L-1. For the process operated in low temperature environment, the average TN removal efficiency was only 57% with an effluent TN of 15 mg L-1, and the average TP removal efficiency was decreased to 67% with an effluent TP of 1 mg.L-1. DGGE analysis indicated that throughout the process, the microbial population within the system maintained its diversity in distribution, while the dominant flora was prominent. During the same period, microbial populations in each compartment were similar. However, the structure of microbial community had significant differences between the ABR and the MBR due to the change of microenvironment in each compartment. Thus, the contributions of the ABR and the MBR were intensified, guaranteeing the efficiency of nitrogen and phosphorus removal in the system.