Characterization on the metabolism in a sequencing membrane batch reactor with deteriorated enhanced biological phosphorus removal activity

Abstract

An enhanced biological phosphorus removal (EBPR) system was developed in a laboratory-scale sequencing membrane batch reactor (SMBR) and with acetate as the sole carbon source. Glycogen-accumulating organisms (GAOs) were observed to be predominant within the populations when EBPR activity deteriorated. The dominant GAOs observed in Stage I and Stage II were non-motile discrete coccobacilli and small cocci packed in clusters, respectively. In Stage I, the sludge was found to take up all of the substrates (acetate, pyruvate, glucose, propionate and lactate) provided under anaerobic, anoxic or aerobic conditions. In Stage II, the sludge could take up the supplied substrates except for glucose and aspartic acid and the uptake rate of acetate was not affected by acetate concentration, but highly dependent on pH in the reactor. It was suspected that glycogen was degraded via the Embden-Meyerhoff-Parnas pathway in Stage I and the Entner-Doudoroff pathway in Stage II to provide energy for anaerobic PHA synthesis.