Membrane Bio Reactor (MBR): It defines a combination of an activated sludge process and WW separation by means of membranes. The MBR process was introduced in the late 60s, as soon as commercial scale ultra-filtration (UF) and micro filtration (MF) membranes were available. The flat sheet membranes used in this process were polymeric and featured pore sizes ranging from 0.003 to 0.01 μm.

The submerged configuration relies on coarse bubble aeration to produce mixing and limit fouling. In submerged configurations, aeration is considered as one of the major parameter on process performances both hydraulic and biological. Aeration maintains solids in suspension, scours the membrane surface and provides oxygen to the biomass, leading to a better biodegradability and cell synthesis. This led to a further development of MBR system.

The popularity of MBR technology lies in following advantages (over conventional processes):

• Most important aspect of MBR technology is production of very high quality effluent consistently.
• Compliance with International stringent discharge norms.
• Complete independent control of HRT (Hydraulic Retention Time) and SRT (Sludge Retention Time), which allow more complete reduction of COD, and improved stability of processes such as nitrification.
• Reduced Sludge Production
• Process intensification through high Biomass concentration with MLSS (Mixed Liquor Suspended Solids) over 8000 – 10000 ppm.
• Ability to treat high strength wastewater.
• Lower footprint than Conventional Activated Sludge Process, since Clarifier/Filters are eliminated.
• Reduction in Post disinfection requirements.

Due to above advantages & recent technical innovations and significant cost reductions the applicability of MBR technology in municipal wastewater treatment has sharply increased in Europe, America, Middle East & China. MBR system is now widely used in industrial applications equally. Large MBR systems are normally built with Hollow Fibre or Tubular membranes & smaller installations prefer Flat Sheet membranes.

MBR applications:

• Residential development projects
• Commercial projects
• Mining camps and other remote installations
• Emergency response
• Military installations
• Sports facilities
• Recreation parks
• Schools
• Shopping centres
• Office parks

KEY BENEFITS:

• Compactness and small footprint of the plant
• Simple management of the plant, as a result of high degree of automation (low dependence on human factor
• Small quantity of excess sludge and therewith connected costs
• Constant effluent quality, regardless of the influent
• Operation costs are lower than in classical biological plant
• Complete bacteria removal
• Possibility of reuse of treated wastewater for irrigation purposes or as process water
• No odours emission or noise
• Fast construction, because of relatively small size of the plant
• Reduced quantity of chemicals needed for phosphorus reduction
• Reduces even slowly degradable BPK5
• No risk of biomass loss
• Flexibility on maximal and minimal inflows, within the given parameters
• No need for permanent crew