Anaerobic membrane bioreactors for wastewater treatment: feasibility and potential applications

Biomass retention is a necessary feature for the successful application of anaerobic digestion for wastewater treatment. Biofilms and granule formation are the traditional way to achieve such retention, enabling reactor operation at high biomass concentrations, and therefore at high organic loading rates. Membrane filtration represents an alternative way to achieve biomass retention. In membrane bioreactors, complete biomass retention can be achieved, irrespective of cells capacity to form biofilms or granules. Membrane bioreactor systems represent then a promising technology for those conditions where biomass aggregation cannot be ensured, or when an effluent completely free of suspended solids is of interest. In the present thesis the feasibility of anaerobic membrane bioreactors (AnMBR) is described, under a wide range of conditions and reactor configurations