A mainstream anammox fixed-film membrane bioreactor with novel sandwich-structured carriers for fast start-up, effective sludge retention and membrane fouling mitigation

Novel sandwich-structured carriers were developed for fast immobilizing anammox sludge, with which a fixed film membrane bioreactor was further established for treating municipal wastewater. Results showed that fast start-up of the fixed-film reactor with anammox bacteria could be achieved without lag phase, indicated by the respective nitrogen removal efficiency and rate of 70.58 +/- 0.66% and 0.12 g N/(L.d). Meanwhile, low membrane fouling 0.0017 bar/hour was also observed. The activity of anammox sludge fixed in the novel carriers gradually stabilized at the level of 6.59 mg N/(g VSS.h), while Candidatus Kuenenia as the dominant anammox bacteria were enriched from the initial abundance of 15.16% to 39.12% after a long-term operation. Consequently, it was demonstrated that the sandwich-structured carriers developed in this study could offer a promising alternative for fast immobilization and start-up of mainstream anammox process.

Automated summary

Novel sandwich-structured carriers were developed for fast immobilization of anammox sludge, establishing a fixed film membrane bioreactor for municipal wastewater treatment. Results showed rapid start-up of the reactor without lag phase, with high nitrogen removal efficiency and low membrane fouling. The activity of anammox sludge stabilized in the carriers, enriching Candidatus Kuenenia as the dominant anammox bacteria for promising alternative in mainstream anammox process.