Abstract
Membrane bioreactors (MBRs) are promising treatment techniques, especially for wastewater, including dense suspension and high salinity. However, membrane fouling is still a critical problem for continuous application. The hydrophilicity of a membrane has so far been considered as one of the important factors contributing to the fouling phenomena. In general, a hydrophobic membrane has a higher development on the fouling than hydrophobic one, however, there is no conclusion in this matter because many contradictory results have also been reported. In addition, there have been only a few studies to reveal the influence of the only membrane hydrophilicity on fouling development in an MBR for a long operation period. In this study, therefore the influence of the only surface hydrophilicity of the membrane on fouling development was investigated using a lab-scale MBR with polytetrafluoroethylene (PTFE) flat-sheet membranes to confirm the influence of membrane hydrophilicity on the fouling development. No remarkable difference in the change of trans-membrane pressure was observed between hydrophilic and hydrophobic PTFE membranes, indicating that the hydrophilicity of the membrane has little influence on the fouling phenomena. The relationship between hydrophilicity and pore fouling resistance were slightly suggested; however, the dominant factor in membrane fouling was cake layer resistance. It was indicated that the adsorption of protein-like compounds, which were present in the suspension liquid, inside the membrane contributed to the pore fouling resistance from the results of extracellular polymeric substances measurement and three-dimensional excitation-emission matrix analysis.
