A novel membrane bioreactor based on membrane distillation

This paper describes a novel wastewater treatment process known as the membrane distillation bioreactor (MDBR). The MDBR process integrates a wastewater bioreactor, such as activated sludge, with membrane distillation (MD). The ability of MD to transfer only volatiles means that very high quality treated water is obtainable, with TOC levels below 1 ppm and negligible salts. A unique feature is that the MDBR allows for the organic retention times to be much greater than the hydraulic retention time. The MDBR uses thermophilic bacteria at about 50°C to treat wastewater. Stable fluxes in the range 2–5 L/m2 h have been sustained over extended periods. A typical experiment is described using a submerged membrane module. The MDBR has the potential to achieve in one step the reclamation obtained by the combined MBR + RO process. For viable operation it would be necessary to use low grade (waste) heat and water cooling. The potential benefits and applications of the MDBR are discussed.