Effect of hydraulic retention time and aeration time on the performance and microbial diversity in an upflow aerobic/anoxic sequential bioreactor

This study investigated the microbial diversity in a laboratory-scale upflow aerobic/anoxic sequential bioreactor (UAASB) with an alternate aeration. A bacteriological study was carried out, as a cultural-based technique, detecting dominant bacteria in the aerobic/anoxic conditions. Central composite design and response surface methodology were applied to investigate the effects of two operating parameters, namely hydraulic retention time (HRT) and aeration time (AT), on the performance of the UAASB. The HRT range of 12-36h, and the AT range of 40-60min/constant time of anaerobic conditions (1h), were examined on the diversity and capability of system. Results of biological investigation showed that HRT and AT have significant effects on bacterial population and diversity, which also is function of organic loading value.