MBR Membrane Bioreactor

Membrane Bioreactor is an emerging technology that combines membrane technology with biochemical reactions in wastewater treatment, also known as the membrane separation activated sludge process. It is a water treatment technology in which membrane filtration replaces the secondary clarifier and sand filter in traditional biochemical treatment technology. It first appeared in the 20th century 70 年s and is currently widely applied worldwide. Compared with traditional biological wastewater treatment technologies, MBR has the following main characteristics: 1. Excellent effluent quality Due to the efficient retention by the membrane, the concentration of Suspended Solids / SS in the effluent is essentially zero; it retains free bacteria and some refractory macromolecular particulate matter, and the biological phase in the bioreactor is rich, such as the enrichment of nitrifying bacteria with longer generation times, while protozoa and metazoa can also grow; the membrane effluent is not affected by factors such as sludge bulking in the bioreactor. Therefore, the effluent quality of MBR is high and can meet the water quality requirements for Reclaimed Water Reuse. 2. Low excess sludge production For the traditional Activated Sludge process, an excessively long sludge age will lead to an increase in Suspended Solids / SS in the effluent, whereas in MBR, due to the retention effect of the membrane, long sludge age operation does not affect effluent quality. The reduction in excess sludge production can lower sludge treatment costs and simplify wastewater treatment process operations, and its advantages are particularly prominent for small wastewater treatment plants and decentralized wastewater treatment facilities. 3. Compact equipment and small footprint Due to the high sludge concentration in the bioreactor, the volumetric loading rate can be greatly increased, and because membrane modules replace the secondary clarifier and filtration equipment, the footprint of the Membrane Bioreactor can be greatly reduced compared with conventional biological treatment processes. Membrane Bioreactors are divided into submerged and external types according to the membrane usage conditions. In the submerged type, the membrane is directly immersed in the biochemical reaction tank, and clean water is drawn directly from the membrane elements, while in the external type, a pump is used to circulate the water from the biological reaction tank through the membrane module for cross-flow filtration to obtain clean permeate. At present, most Membrane Bioreactors in operation worldwide are of the submerged type.