Ammonia-Oxidizing Bacteria (AOB): opportunities and applications—a review

Recently, partial nitrification has been adopted widely as a first step of both nitrite shunt and deammonification processes towards efficient and economical nitrogen removal from wastewater. Effective partial nitrification relies on stimulating the first step of nitrification while inhibiting the second step and by consequence accumulating ammonia-oxidizing bacteria (AOB). Successful AOB accumulation depends upon the knowledge of their microbial characteristics and kinetics parameters as well as the main parameters that can selectively inhibits NOBs' growth or allow AOBs to outcompete them. Several bioreactors configurations either in suspended or attached growth have been used towards achieving partial nitrification using different inhibition conditions. This review aims to illustrate an up to date version of the metabolism and factors affecting AOB growth and summarize the current bioreactors configurations in all lab-scale and full-scale applications for AOB. Moreover, successful partial nitrification attempts in the literature in suspended and attached growth systems have been complied. Additionally, the possibility of improving the current applications of AOB and the integration into the operation of existing WWTPs in order to transform into water resources recovery facility has been presented.