A submerged membrane assembly including a membrane having a first surface, a second surface, and a vertical axis, and which is permeable between the surfaces by molecules of less than a predetermined size. A first fluid compartment in fluid communication with the first membrane surface and that contains at a first column height a first fluid having a first specific gravity, a second fluid compartment in fluid communication with the second membrane surface and that contains at a second column height a second fluid having a second specific gravity, and means for changing the second specific gravity. The second column height being selected relative to the first column height to produce a selected pressure differential across the membrane along the vertical axis at the first specific gravity and the changed second specific gravity.

In a vertical shaft bioreactor, improved devices and methods are provided for enhanced secondary and/or tertiary treatment of wastewater, including residential, municipal and industrial wastewater. The devices and methods of the invention are useful for enhanced secondary wastewater treatment, including BOD and TSS removal. Tertiary treatment can alternately or additionally be achieved in the bioreactor with nitrification of ammonia, with nitrification and denitrification, and with nitrification, denitrification, and chemical phosphorus removal. A vertical shaft bioreactor is also provided which achieves thermophilic aerobic digestion and pasteurization of sewage sludges, optionally to produce class A biosolids.

In a vertical shaft bioreactor, improved devices and methods are provided for enhanced secondary and/or tertiary treatment of wastewater, including residential, municipal and industrial wastewater. The devices and methods of the invention are useful for enhanced secondary wastewater treatment, including BOD and TSS removal. Tertiary treatment can alternately or additionally be achieved in the bioreactor with nitrification of ammonia, with nitrification and denitrification, and with nitrification, denitrification, and chemical phosphorus removal. A vertical shaft bioreactor is also provided which achieves thermophilic aerobic digestion and pasteurization of sewage sludges, optionally to produce class A biosolids.