Amongst various types of in-situ sl

Amongst various types of in-situ sludge reduction technologies in-corporating uncoupled metabolism of bacteria, the oxic-settling-anae-robic (OSA) processes have been considered as the most viable option todecrease the production of the excess sludge in biological wastewatertreatment processes. This is due to the efficient reduction of the excesssludge without any additional physiochemical treatments, high level ofoperational flexibility, significant improvement of sedimentation cap-ability, and the convenience of reconstruction in the OSA processes(Guo et al., 2013). On the other hand, despite the efficient reduction ofthe excess sludge production in the OSA processes, their effluents stillcontained considerable amount of nutrients, which cannot satisfy theregulations for rising effluent qualities (Coma et al., 2013).