Impact of water characteristics on the bioenergy recovery from sewage treatment by anaerobic membrane bioreactor via a comprehensive study on the response of microbial community and methanogenic activity

Effect of wastewater characteristics on bioenergy recovery in sewage treatment by anaerobic membrane bioreactor (AnMBR) was investigated. Based on COD removal, sludge concentration change and COD mass balance, nonionic surfactant or operation at 20–25 °C had no effect on the energy recovery with COD conversion of 72–79%. The anaerobic microbes can cope with the characteristic by releasing more SMP/EPS or changing its community structure. Compared with Control (6.99 × 10⁷ kJ/d, HRT 12 h), with suspended solid or operation at 15 °C and 10 °C, the captured energy was only 5.90 × 10⁷ kJ/d, 6.0 × 10⁷ kJ/d and 3.10 × 10⁷ kJ/d, respectively while the energy in dissolved methane was 1.08 × 10⁷ kJ/d, 0.98 × 10⁷ kJ/d and 1.26 × 10⁷ kJ/d. Hence, the recovery efficiency was decreased by 15.6%, 14.2% and 55.7%. The recovery also decreased by 26% (5.17 × 10⁷ kJ/d) in the presence of anionic surfactant. The toxicity of anionic surfactant to the anaerobic microbes and lower growth rate of microorganism at psychrophilic temperatures were responsible to the decrease of bioenergy recovery efficiency. SS accumulation will finally increase the loading rate of sludge and decrease the bioenergy recovery from the long-term view.