ABSTRACT
Membrane bioreactor (MBR) combines biological treatment and membrane separation to produce a very high-quality effluent with extremely low suspended solids concentrations. However, this does not mean that high-quality effluent is always produced stably. High-quality effluent is difficult to produce if optimal conditions for microorganism function are not maintained. This is because the treatment of wastewater pollutants (e.g., organic and particulate biodegradable matters, inorganic nutrients, and nonsettleable colloids) is dependent on the activity of microorganisms in bioreactors in MBR plants. Moreover, the characteristics of microbiological floc (e.g., size and the content of filamentous microorganisms) are influenced by the bioreactor operational conditions, and they affect the fouling properties of the membranes. Proper operation of bioreactors in MBR plants is thus essential to achieve the objective of wastewater treatment. A comprehensive understanding of biological wastewater treatment will provide the fundamentals for designing and operating optimal bioreactors in MBR plants.
