Study on Correlation between Impact-Resistance Performance and Microbial Characteristics by MPSR and SBR under Transient Organic Load Shock

Abstract

The single-cycle transient high-concentration organic load shock test was conducted on the micropressure swirl reactor (MPSR) and sequencing batch reactor (SBR) to assess their capability to different levels of transient organic load shock (OLS), including pollutant removal, sludge characteristics, and microbial characteristics. The results indicated that the impact-resistance of biological treatment systems was related to reactor structure and microbial community distribution. When subjected to transient chemical oxygen demand (COD) load of 0.81, 1.28, and 1.70 g/(L·day), respectively, both reactors exhibited effective organic removal capabilities. Compared with MPSR, within a certain shock range, nitrification in the SBR was less affected by shock and had a higher effect on nitrogen and phosphorus removal. However, when shock load reached 1.70 gCOD/(L·day), the denitrification was sufficient in the MPSR, and microorganisms continued to secrete polysaccharides (PS), which was beneficial for adsorbing pollutants and resisting impacts. Under steady-state conditions, the SBR exhibited excellent nitrification with a relative abundance of 60.7% for nitrifying functional groups such as Thiothrix. Compared with the SBR, the MPSR displayed a higher microbial community diversity, with a variety of phosphorus-removing bacteria and denitrifying bacteria genera occupying aerobic and anoxic partitions within the same space, which was profitable for effective denitrification and phosphorus removal under high OLS. Besides, the enrichment of Flavobacterium and Zoogloea sp. at high concentrations significantly enhanced the MPSR’s resistance to OLS. This study provides a theoretical basis for effective measures by different processes in response to organic load shocks.