Biodegradation of Emerging Organic Micropollutants in Nonconventional Biological Wastewater Treatment: A Critical Review

Biodegradation is the predominant removal mechanism for emerging organic micropollutants (EOMs) in wastewater and a promising approach to fully degrade these compounds during wastewater treatment (WWT). This review aims to deliver an up-to-date scientific and technical overview of EOM biological removal during WWTs with a focus on nonconventional biological treatment to include: hybrid activated sludge and membrane bioreactor systems; immobilized, packed-bed, and granular systems; and electro-biochemical treatment. Individual microorganisms that have proven effective in degradation of EOMs commonly found in municipal wastewaters (pesticides, industrial chemicals, disinfectants, and some pharmaceuticals) are included, and elucidated metabolic pathways involved are discussed. Factors that influence biological removal of EOMs in complex wastewater matrices during nonconventional WWTs are assessed based on 25 studies, which provide data on the removal of 151 EOMs and 398 different treatment conditions. Furthermore, in silico tools are discussed, highlighting how they could be used as time-saving approaches to further EOM biodegradation research. Links among these sets of studies are used to identify trends and limitations, to propose future cutting edge research directions to improve biological EOM removal during WWT. Overall, bioremediation has the hallmark of an effective means for removal of EOMs, provided that a well-directed and systemic approach is found to study and implement these complex mechanisms in existing or new WWTs.