Fouling potential and membrane fouling determination during the treatment of sewage and stabilized leachate using a pilot scale submerged MBR

The fouling potential of membrane bioreactor biomass developed from sewage and mature landfill leachate feedwaters was assessed using a pilot scale Membrane Bioreactor (MBR) operating polymeric and ceramic air-lift sidestream multi-channel membranes. The plant was operated under identical conditions of sludge retention time, system hydrodynamics and parity of F/M ratios. Biomass samples were extracted and fractionated (fixed and bound material; carbohydrate and protein extracts) and chemically and physically analyzed, along with the feedewaters. Both ceramic and polymeric membranes were tested and the critical flux determined according to the classical flux-step analysis. Although permeability (K) of both materials reduced with increasing flux (J) the ceramic material had a higher resistance to fouling, demonstrating a higher K (by a factor of 1.2 and 3.2 for sewage and leachate respectively at J of 30 L.m−2.h−1) and lower dP/dt (by more than an order of magnitude at the same J) than the polymeric membrane. Evidence suggests that the high fouling propensity of the leachate biomass arises from the feedwater itself, rather than the products derived from the biomass, and that colloidal and/or soluble TOC represents the principal foulant.