Biofouling on microfiltration membranes in MBRs: Role of membrane type and microbial community

Cross-flow filtration experiments were performed using three model biofoulants with increasing complexity: a monospecies assay using Pseudomonas aeruginosa or Escherichia coli, a duospecies assay using both microorganisms, and finally a multispecies assay using activated sludge spiked with P. aeruginosa. Three different microfiltration membranes were tested: polyvinyldifluoride, polyethylene and polysulfone. The biofouling was characterized in terms of cell density, community composition and relative permeability decrease caused by the different biofoulants. The data show that a good biofilm pioneer, like P. aeruginosa, was able to bind to any kind of membrane. However, when activated sludge spiked with P. aeruginosa was used, an enhanced biofouling behavior by the activated sludge members was found on the polyvinyldifluoride membrane. This paper highlights the importance of the kind of species, the microbial interactions and the community composition during the biofouling development.