The MBR process is an advanced technology that consists of a suspended growth biological reactor integrated with an ultrafiltration membrane system, using hollow fiber membranes. The ultrafiltration system replaces the solids separation function of secondary clarifiers and sand filters in a conventional activated sludge system. Ultrafiltration membranes are immersed in an aeration tank, in direct contact with mixed liquor. The permeate pump draws the treated water through the hollow fiber ultrafiltration membranes. Permeate is then directed to disinfection or discharge facilities. Intermittent airflow is introduced to the bottom of the membrane module, producing turbulence that scours the external surface of the hollow fibers. This scouring action transfers rejected solids away from the membrane surface. MBR technology effectively overcomes the problems associated with poor settling characteristics commonly found of sludge in conventional activated sludge processes. MBR technology permits bioreactor operation with considerably higher mixed liquor solids concentrations than conventional activated sludge systems that are limited by sludge settling. The MBR process is typically operated at a mixed liquor suspended solids (MLSS) concentration in the range of 8,000 to 12,000 mg/L. Elevated biomass concentrations allow for highly effective removal of both soluble and particulate biodegradable material in the waste stream. The MBR process combines the unit operations of aeration, secondary clarification and filtration into a single process, producing a high quality effluent, simplifying operation and greatly reducing space requirements. The ultrafiltration membrane removes virtually all suspended solids and biomass, ensuring the highest clarity and quality of final effluent of all technologies used in wastewater treatment. The ultrafiltration membrane is a robust barrier to the passage of all solids in the event of plant upsets. Often, the final effluent from an Ultrafiltration membrane system is of reuse quality, allowing operations to consider the additional opportunity and savings potential to reuse water rather than discharge.