Literature Review on Membrane Biofouling Occurring in MBR and Its Related Technologies for Greywater or Wastewater Treatment

Abstract

This review provides an overview of membrane biofouling of the present MBR and its advanced related technologies to treat greywater and wastewater for solving the global water reuse problem. MBR is a competitive technology for wastewater treatment. HMBR, MBMBR, OMBR have shown a better membrane performance and fouling resistance than MBR. Most of the studies considered
in this review were discussing factors causing membrane fouling and the fouling mechanism. In MBR and its related technologies, key microbial species in wastewater biological treatment are different from each other. There are several kinds of bacteria that could adhere to membrane surface to induce severe membrane fouling while treating domestic water such as greywater and blackwater. However, the ones causing membrane fouling are all related to filamentous species, which could cause negative effects on membrane fouling. The biomass growth in HMBR and MBMBR is both suspended and attached, while the biomass in MBR and OMBR are just suspended. Autotrophic-heterotrophic bacteria ratio and anaerobic-aerobic ratio are key parameters for microbial community and contaminants removal. Different microbial species prefer to remove different contaminants. They are affected not only by influent source but also by some environmental parameters. Nowadays, the reason for membrane fouling focuses on extracellular polymeric substances (EPS) and soluble microbial products (SMP), mostly excreting by microorganism in MBR system. EPS/SMP could help bioflocs attachment on the membrane
surface in the first stage fouling and cause the accumulation on membrane surfaces and within the pore structure for cake formation and pore blocking respectively, which are the dominant fouling modes. To control EPS, it’s a good way to control factors influencing biomass growth rate and biomass performance, such as sludge loading rate, HRT and organic loading rate, and control filamentous bacteria overgrowth. To control SMP, it can be achieved by adjustment of operation parameters (SRT, HRT, DO concentration, temperature, aeration) and addition of adsorbents or coagulants. Membrane fouling, which still remains a major problem for all membrane bioreactors, still needs further discussion.

Keywords: membrane fouling, MBR and its related technologies, wastewater treatment, microbial community, EPS/SMP