Pressure has been increased on authorities for efficient waste water treatment with environmental consideration due to rapid growth and urbanisation (EU, 2010). Various physical, mechanical, biological and chemical methods of water treatment have been used to remove suspended solids, organic matter and dissolved pollutants or toxins. Membrane bioreactor (MBR) has been regarded as one of the processes in the treatment of waste liquids.
Membrane bioreactor is a combination of biological treatment process and membrane filtration. Membrane is a thin material with a narrow range of pore size and high surface porosity that resist the transfer of different constituents of a fluid (Visvanathan and Aim, 2000). The membrane filters suspended solids and is an alternative for conventional filtration and sand filtration in the treatment of industrial wastewater and municipal sewage (EU, 2010).
Membrane filtration processes are classified according to the membrane pore sizes: microfiltration (0.1 to 10 microns), ultrafiltration (0.003 to 0.1 microns), nanofiltration (0.001 microns) and reverse osmosis (0.0001 microns) (EU, 2010).
Membrane bioreactor has a number of advantages like good effluent quality with high hygienic standards, high possible biomass concentration, reduced reactor volume and footprint and reduced net sludge production (Kraume, 2012). MBR can provide advanced level of nutrient removal (Fitzgerald, 2008).
Research is on-going to limit drawbacks associated with MBR. High investment costs of membrane modules, high operating costs associated with energy consumption and membrane integrity are limitations of MBR (Kraume, 2012).
European Union (2010) Membrane technologies for water applications Highlights from a selection of European research projects [Online] Available athttp://ec.europa.eu/research/environment/pdf/membrane-technologies.pdf [Accessed on 27 August 2012].
Fitzgerald, K.S. (2008) Membrane bioreactors. [Online] Available at http://www.tsgwater.com/pdf/MBR%20Synopsis.pdf [Accessed on 27 August2012]
Kraume, M. (2012) Membrane Bioreactors. [Online] Available at http://www.zer0-m.org [Accessed on 27 August 2012].
Visvanathan, C. and Aim, B.R.(2000) Membrane Bioreactor Applications in Wastewater Treatment [Online] Available at http://www.faculty.ait.ac.th/visu/pdfs/Activities/Participation/RMBEE.pdf [Accessed on 27 August 2012].