8 - Nutrients removal in membrane bioreactors for wastewater treatment

Abstract

The increasingly stringent requirements regarding effluent quality call for more efficient activated sludge processes especially in terms of the effective and efficient removal of nitrogen (N) and phosphorus (P). Membrane bioreactor (MBR) treatment involves the combination of membrane filtration with a biological degradation process using activated sludge and shows much better effluent quality compared with activated sludge processes for wastewater treatment owing to its higher concentration of mixed liquor suspended solids (MLSS), longer sludge retention time (SRT), and hydraulic retention time (HRT). This chapter presents an overview of basic principles of biological removal of nutrients (N and P), current status and recent developments of nutrients removal in MBRs for wastewater treatment. Firstly, the nitrification and denitrification processes for the N removal were briefly reviewed followed by the P removal process, especially the enhanced biological P removal (EBPR) process with phosphorus-accumulating organisms (PAOs). Secondly, the bacteria particularly at the genus level responsible for the N and P removal were systematically identified. Finally, the effect of chemical dosing, MBR configuration, addition of supporting media, and the integrated process with MBR on the removal of nutrients (N and P) in MBRs for wastewater treatment were systematically reviewed and compared, and meanwhile the ongoing challenges and opportunities were addressed.