Role of Membrane Biofilm in Psychrophilic Anaerobic Membrane Bioreactor for Domestic Wastewater Treatment

摘要

Anaerobic membrane bioreactors (AnMBRs) combine anaerobic biological treatment andmembrane separation in a single process and have been identified as a possible approach toincrease the sustainability of domestic wastewater treatment. Results from bench-scaleAnMBR treatment of domestic wastewater at psychrophilic temperatures indicate thepotential to meet U.S. EPA’s standards for secondary treatment with this technology.Observations during AnMBR operation indicate that the membrane biofilm provides asubstantial part of the overall COD removal accomplished and that a trade-off exists betweenthis COD removal and membrane fouling. A preliminary experiment indicated that thebiofilm removes mainly soluble COD and that the mechanism of soluble COD removal isprimarily biological. Biological activity in the biofilm produces additional methane and thiscombined with pressure gradients from membrane operation may increase methane solubility,limiting direct biogas recovery. This experiment also suggested that hydrogenotrophicmethanogens may have increased activity in the biofilm relative to aceticlastic methanogens.This was affirmed through pyrosequencing of 16S ribosomal RNA genes in DNA extractedfrom AnMBR biofilm samples.