Kinetic estimation of low excess sludge and extracellular polymeric substance accumulation in a vertical submerged membrane bioreactor (VSMBR)

The main objective of this study was to investigate reasons of mitigated membrane fouling based on a mathematical prediction of daily excess sludge (DES) and extracellular polymeric substance (EPS) accumulation in a laboratory-scale vertical submerged membrane bioreactor (VSMBR) fed with glucose. Yield coefficient, growth rate, and decay rate of autotrophic and heterotrophic micro-organisms were estimated by measuring oxygen uptake rate (OUR). From kinetic estimation, it was concluded that the DES from the VSMBR was only 4% of the total DES produced by the activated sludge process (ASP). This resulted from the lower yield biomass and the higher decay of heterotrophic biomass in the VSMBR. In part of the experiment, transmembrane pressure (TMP) was affected by a rapid increase in EPS concentration. Later, a second rapid increase of TMP was observed although EPS concentration was stable indicating that the second increase of TMP was caused by interfiber clogging other than EPS accumulation.