Membrane bioreactor with reduced air scour requirements

In a sewage treatment system and process, a method for increasing efficiency in an intensified process including membrane separators in which water is removed from mixed liquor, wherein superoxygenation and air scour are employed, comprising:

• supersaturating influent wastewater or mixed liquor with oxygen in an oxygenation zone prior to biological treatment, so that the wastewater or mixed liquor is oxygenated beyond normal saturation content of water at atmospheric conditions, to an oxygen content of at least 15 parts per million, and at sufficient flow rate of the wastewater or mixed liquor through the oxygenation zone to allow for an oxygen uptake rate beyond 150 mg/l/hr thereby intensifying the process,
• introducing the oxygen-supersaturated wastewater or mixed liquor into a biological process zone requiring oxygen, thereby causing part of the oxygen in the mixed liquor to be taken up to support the biological process, and
• directing the mixed liquor to membrane separators in an MBR zone to remove water, whereby the dissolved oxygen can meet most of process oxygen demand, while causing some of the oxygen in the mixed liquor to evolve from solution in the MBR zone as relatively large bubbles which form and rise to the membrane separators with sufficient velocity to cause air scour of the membrane separators in the MBR zone.