Membrane bioreactor technology (MBR) is a relatively new wastewater treatment technology, based on a combination of membrane separation and biodegradation; it uses membrane separation to keep large biosolids and useful microorganism inside the reaction tank. It allows achieving higher concentration of activated sludge, improving solids retention time (SRT). With this arrangement the hydraulic retention time (HRT) and SRT can be set separately keeping slow-growing microorganisms in the reactor continually. MBR also enhances the biochemical efficiency, resistance to shock loads, water quality variations and improves stability of the whole process. Smaller equipment size and fully automated control are also important benefits of this technology. MBR is currently one of the most promising wastewater treatment technologies widely researched and applied in Japan, France, US and Canada and other countries.
High and stable effluent quality, low effluent TSS concentration;
Small footprint. MBR can be operated at a higher volumetric loading rates, resulting in a shorter HRTs and longer SRTs. Moreover, membrane filtration can replace the secondary clarifier, also reducing the system size;
Low sludge production. Longer SRTs and high activated sludge concentration in the reactor, allows achieving better biodegradation rate with a lower biomass production;
Nutrients removal. Adding the anaerobic zones to MBR can be used to enhance ammonium, total nitrogen, and phosphorous removal rates. In this case membrane also provides long SRTs, required for nutrient removal;
Better SRT and HRT control. Using membrane for activated sludge straining allows achieving independent HRTs and SRTs, simplifying the operation;
Aeration tank. The aeration can be used to enhance the degradation rate of the organic matter and sludge growth rate, increasing the biosolids concentration. High activated sludge concentration (up to 20,000 mg/L of MLSS) along with membrane retention ensures stable operation and resistance to shock-loadings;
Large contact area. MBR configuration helps to provide uniform distribution of biosolids throughout the reactor, preventing the formation of large flocs and increasing the contact area and biodegradation efficiency of the system;
Integration and automatic control. Due to its low footprint, MBR is much easier to integrate into the existing system or combine with other treatment methods. Its reliability and stability are important for full automatization and control.