Chapter 10: Anaerobic Fluidized Bed Membrane Bioreactors for the Treatment of Domestic Wastewater

The anaerobic fluidized bed membrane bioreactor (AFMBR) is a new energy-neutral methanogenic biological treatment system that combines an anaerobic fluidized bed reactor (AFBR) and internal membranes. It is unique in that the fluidized granular particles, while serving as a surface for active biofilm attachment, rub against membrane surfaces, resulting in a reduction in fouling with low energy expenditure. Fluidized particles denser than water permit good mass transfer, and allow for the maintenance of a large biological population, even at the short hydraulic retention time as required for dilute wastewater treatment. Membranes prevent the escape of volatile suspended solids so they can be biodegraded adequately and removed separately for subsequent disposal. The AFMBR can be used alone for wastewater treatment or as the second reactor in a staged treatment system. Laboratory and pilot studies with domestic wastewater with a staged AFBR–AFMBR system, both containing granular activated carbon particles and operated at total HRT near 6 h and temperatures down to 8 °C, have demonstrated high organic removal efficiency, low waste biosolids production (0.05 kg·kg-COD⁻¹), microcontaminant removal efficiencies better than conventional aerobic activated sludge treatment, and a very small footprint. Further research on best approaches for dissolved methane capture and nutrient removal and recovery are ongoing.