Application of deep-sea psychrotolerant bacteria in wastewater treatment by aerobic dynamic membrane bioreactors at low temperature

• DMBR inoculated with psychrotroplis bacteria operated well at low temperature.
• Shorter start-up time and better performance were observed for the augmented DMBR.
• Bioaugmentation could enhance the ability of dehydrogenase activity.
• FISH analysis further confirms the presence and activity of two strains at 5 °C.

Wastewater treatment by biological processes was greatly hindered at low temperature. To improve the performance, screened deep-sea psychrotolerant strains were inoculated into an aerobic dynamic membrane bioreactor (ADMBR). The effect of bioaugmentation on reactor start-up, wastewater treatment performance, dynamic membrane formation, and membrane fouling under different temperature conditions was studied. Compared to the control reactor, the bioaugmented reactor showed a shorter start-up period, and better wastewater treatment performance at ≤15 °C for a sudden decrease, and ≤7 °C for a gradual decrease in temperature. Dehydrogenase activity in the bioaugmented reactor was enhanced at low temperature. Severe membrane fouling was not observed with bioaugmentation and the nonwoven fabric module we used was convenient to clean with tap water. Insoluble extracellular polymeric substances, especially insoluble protein were found to be responsible for membrane fouling. Fluorescence in situ hybridization (FISH) analysis displayed the dominance of two inoculated strains at the low temperature of 5 °C. This study gave evidence that bioaugmentation with psychrotolerant strains was a feasible strategy to shorten the start-up time and to improve the wastewater treatment for ADMBR at low temperature.