Review on the state of science on membrane bioreactors for municipal wastewater treatment.

Over the past two decades the field of application for membrane bioreactors has broadened towards the municipal wastewater treatment sector. The Global Water Research Coalition (GWRC) determined MBR technology to be of priority for collaborative research and decided to conduct a project with the aim to determine the current state of the science in the field of MBR for municipal wastewater treatment and to develop a phased research strategy represented by priority research projects, like a State of the Science report with regard to MBR technology. This paper describes the state of the science with regard to MBR technology for municipal wastewater treatment by 2007, derived by literature review on recent publications, database analysis and international questionnaires. The research efforts from the past seven years can be characterised by the following prioritised list: (1) membrane fouling, (2) effluent quality, (3) energy consumption (aeration) and (4) cost considerations. The research needs for the near future as identified with the questionnaire are comparable to the main topics of research as identified in the literature review: membrane fouling is still the main problem requiring thorough attention from scientists; effluent quality is a main driver for the application of the technology. There remain some important questions however, with regard to the removal of EDC and micro pollutants. Much of the research activities on MBR are repeated more than once by research groups world-wide. This is only partially caused by a lack of knowledge exchange between researchers. However, lacking information exchange between Europe and the USA on MBR research is identified as a potential bottleneck. Another point of attention is the fast that research results can not easily be translated to other (more practical) situations, since much of the research is carried out at pilot scale.