Greater attention and ongoing development work is happening in waste Water and particularly in MBRs. Hollow fiber , sheet and tubular are three types of configuration are available in market now a days. The process combines mixed liquor activated sludge, operating at high concentration, with ultrafilter membranes for biomass separation. Initially the process was limited to small wastewater flows where high quality treated effluent is required, due to high capital cost. With the awareness and ever increasing demands for higher effluent quality, MBRs are very much in demand and being applied in larger municipal sewage treatment plants as well as Industrial sectors now.
The system operates on a continuous basis by controlling the rate of permeate flow from the membrane modules. A recirculation pump feeds mixed liquor from the bioreactor to the bottom of each module where air is injected. This, in effect, acts as an airlift pump increasing the velocity that aids scouring inside the membranes. The scouring mixers discharges from the top of each module and is returned to the bioreactor (or the anoxic zone for de-nitrification). Back-flushing with initiated on a time cycle to each bank of modules. This removes any cake formed on the inside of the membrane tubes, thus maintaining flux rates.