Comparative Study On The Characteristics Of N₂O About Wastewater Treatment Process

Nitrous oxide (N2O) production from wastewater biological nitrogen removal process is the potential source of N2O production, and different wastewater treatment processes have significantly affected N2O production in biological nitrogen removal process. Three wastewater treatment processes (SBR process, A2N process, smulti-level step feed A/O biological filter) were used in this investigation. In the process of nitrification and denitrification, N2O productions and factors have compared in various systems to find the optimal control to reduce N2O productions and the optimal process conditions.The major findings of the one-year research are listed below:(1) Wastewater treatment processes has a major effect of N2O generation, the amount of N2O production in the smulti-level step feed A/O biological filter is the least, A2N process followed, SBR process is the most.This system emitted1.945mg/l,2.105mg/l,4.721mg/l N2O,accounting for removed nitrogen4.56%,6.15%,7.67%, respectively.(2)The dissolved oxygen concentration is considered as a very important parameter of N2O production during nitrification, and the C/N ratio is very significant during denitrification. To reduce the amount of N2O production, it should be reasonable controlled in the most appropriate range of2.0mg/L and C/N ratio of4.0.(3)Microbial community structure is different if sludge has different characteristics of N2O production, smulti-level step feed A/O biological filter feed the micro-environment suitable for a variety of microbial growth and reproduction.The analysis of PCR-DGGE fingerprint showed that the microbial communities of Bio-ceramic in smulti-level step feed A/O biological filter were very abundant in high diversity. In contrast, in A2N process and SBR process the microbial communities of sludge have lack diversity.(4)Different wastewater treatment processes have different microbial communities living micro environments. Analysis of the comparability of the microbial communities using the UPGMA clustering algorithm, it showed that the similarity of the microbial communities between A2N process and SBR process was18%, and the similarity of the microbial communities between smulti-level step feed A/O biological filter and A2N process was14%.Comparison of N2O production and microbial communities in the wastewater treatment process, it provided a favorable theoretical basis and technical support that the optimal process generated the least N2O.Therefore, the choice of low N2O production in smulti-level step feed A/O biological filter have a certain reference value on wastewater treatment and environmental protection.