membrane biological reactors (mbr) and their applications for water reuse

the term 'membrane bioreactor' expresses a combination of activated sludge and membrane separation processes. the need to processes like sedimentation and disinfection used in common methods is eliminated through mbr systems in a way that membranes are placed into or out of an aeration tank and the vacuumed wastewater created by the suction pump is pulled up from inside the membranes and leaves the mixed liquid suspended solids (mlss) inside the aeration tank. mbr allows biological processes to work in a long srt (20 to 100 days generally) and therefore concentration of the mlss can increase even higher than 10000 mg/l. 93-99% removal of bod, cod and 85-97% nitrification performance has been proved by different experiments. membrane filtration removes biological pollutants, particulate materials and colloid dilution, turbidity, microorganisms, suspension impurities and elements such as iron and manganese. concerning the advantages of this system, smaller required space due to the omission of sedimentation tank, extra disposable sludge production reduction about 60-75 percent, constant effluent quality and its independence from influent can be mentioned. membrane fouling and its periodic replacement are the main disadvantages of this system. membrane bioreactor technology can be used as a technology to treat different types of wastewater and to produce effluent with a good and suitable quality for reusing.