Membrane bioreactors combine the front-end of traditional wastewater treatment processes with a membrane separation process, like ultrafiltration (UF) or microfiltration (MF), to treat industrial and municipal wastewater. The back-end of a traditional wastewater process normally involves settling tanks and some form of filtration and disinfection. A membrane bioreactor can replace this back-end process, with the membrane separation process performing liquid/solid separation, and filtration of bacteria, parasites, and viruses.
The membrane filter is normally submerged into the untreated wastewater. By creating a slightly negative pressure, the filtrate (filtered water) is drawn through the membrane filter, while solids, bacteria, parasites, viruses, etc. are left in the bioreactor to be digested by bacteria or settle as sludge. Fouling of the membrane filter is reduced or prevented by aeration. Small air bubbles are passed around and between the sheets of the membrane filter, dislodging any accumulated sludge on the upstream side of the filter.
Exceptional effluent quality from a membrane bioreactor is possible, with 99.999% virus removal, turbidity of less than 1 NTU, and biochemical oxygen demand (BOD) of less than 5 mg/L.
Considerations in the design of a membrane bioreactor include: the influent quality, the wastewater flow rate, and the required effluent flow rate.
Please follow the links to view the various types of equipment used in membrane bioreactors.
