Discrepant membrane fouling of partial nitrification and anammox membrane bioreactor operated at the same nitrogen loading rate. (August 2016) - Niu, Zhao
Graphical abstract: Highlights: Anammox–MBR has a more serious membrane fouling than PN–MBR. It caused by different microbial products of nitrifiers and anammox bacteria. Anammox bacteria metabolites are more hydrophobic than that of nitrifiers. Hydrophobic PVDF membrane absorbs more hydrophobic anammox bacteria than nitrifiers. Abstract: In this study, two times more serious membrane fouling was found in anammox membrane bioreactor, compared to partial nitrification membrane bioreactor (PN–MBR) operated at the same nitrogen loading rate. By protein, polysaccharide, amino acids and functional groups analysis, it was found that the discrepancy in membrane fouling was virtually due to the difference in microbial products of nitrifiers and anammox bacteria. Protein and polysaccharide were main foulants on membrane surface; meanwhile theirs content and ratio in the EPS, supernatant and membrane surface were significantly different in PN–MBR and anammox–MBR. The anammox metabolism products contained much more hydrophobic organics, hydrophobic amino acids, and hydrophobic functional groups than nitrifiers. A mass of anammox bacteria as well as hydrophobic metabolism products deposited on the hydrophobic membrane surface and formed serious fouling. In further, hydrophilic modification is more urgently needed to mitigate membrane fouling when running anammox–MBR, than PN–MBR.