Aerobic and anaerobic biodegradation of polyethylene glycols using sludge microbes

The aerobic and anaerobic biodegradation of polyethylene glycols (PEGs) in a model wastewater was investigated employing sludge microbes from Xiamen Terylene plant. The effect of molecular weight (MW) on the aerobic/anaerobic biodegradation of PEGs was assessed by performing shake flasks/sealed flasks experiments, respectively, using organic model wastewater containing PEG 600, 6000 and 20,000. In aerobic biodegradation, although there were differences between the degradation processes, the three kinds of PEG were all degraded by about 80% in 5 days, regardless of the wide diversity of MW. In anaerobic biodegradation, about 50% degradation of PEG 600 in 9 days, 40% degradation of PEG 6000 in 10 days and 80% degradation of PEG 20,000 in 6 days were obtained. The effect of nutrition on anaerobic degradation was also investigated. The biodegradation rate of PEG 6000 increased sequentially in the organic, inorganic and enriched organic media. The latter two were similar to each other. In the enriched organic media PEG 6000 was degraded by 50% in 10 days and 70% in 14 days, while in the organic media the degradation rate was 23% in 10 days and 50% in 14 days. It was notable that the anaerobic microbes could use PEG 6000 as sole carbon source, and PEG MW up to 20,000 was efficiently biodegraded in this study, either in aerobic or anaerobic way.