The optimized microbial community composition in the integrated 2-step sludge alkaline fermentation and A2 O system might substantially improve the removal of nutrients (total nitrogen (TN) = 11%, total phosphorous (TP) = 11%), as well as the reduction of the excess sludge (42%) (Gao et al., 2011). Furthermore, signifificant increases were observed in the reduction of the excess sludge and the removal of nutrients in the modifified OSA and sequencing batch reactor processes due to the variations in their microbial community composition (Yang et al., 2016). Nevertheless, it was diffiffifficult to adjust the operating conditions (e.g., temperature, oxidation-reduction potential, sludge retention time etc.) for enhancing the performance of the modifified OSA processes due to the complex removal mechanisms (Semblante et al., 2014).