Feasibility of Achieving Efficient Nitrite Accumulation in Moving Bed Biofilm Reactor: The Influencing Factors, Microbial Structures, and Biofilm Characteristics

Moving bed biofilm reactor (MBBR) is considered as a promising technology for wastewater treatment owing to the high biomass retention and low cost. In this study, performance of using MBBR partial denitrification (PD) was investigated. Denitrifying successfully formed after 40 days with nitrite reduction rate 40.83 mg VSS/g carriers 51.52 N/(gVSS·h), respectively. Morphology analysis by scanning electron microscope (SEM) showed that surface dominant cocci, filamentous bacteria, extracellular polymeric substances (EPS). Investigation about influencing factors PD found optimal COD/NO3−-N pH efficient production (nitrate ratio: 96.49%) 3 9, Moreover, Saccharimonadales proved be functional microbes in constructed systems different influent conditions because its relative abundance exhibited good correlation accumulation. By analyzing characteristics under conditions, observed mainly occur range 300–700 μm inside biofilm, where most dissolved oxygen consumed. This study confirmed feasibility superior PD-MBBR system.