Bioaugmentation as a useful strategy for performance enhancement in biological wastewater treatment undergoing different stresses: Application and mechanisms

The operation of biological processes may face the challenges of system instability and performance deterioration under different stresses, including transient shock of toxic matters/substrates in wastewater and cold temperatures. Bioaugmentation (BA) has been considered as a useful strategy playing an excellent role for performance enhancement and recovery in biosystems under various stresses due to the improvement of detrimental conditions, retention and adaptation of BA consortium, reactivation, and quorum-sensing effect. However, BA faces the potential risk of functional failure, even negative effects on biosystems. Measures should be used to resolve this risk, such as balancing the relationship between BA functional consortium and indigenous organisms, substrate, physical and chemical conditions, and so on. The application and mechanisms of BA, as an effective tool widely used in different stress scenarios, are detailed and discussed. Especially, the key point of successful application of BA is quantifying when and how BA is effectively implemented. Therefore, in-depth research on the BA time, BA dosage, BA interval with their relationship in different biosystems was suggested in the future.