期刊
SCIENCE OF THE TOTAL ENVIRONMENT
卷 864, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.scitotenv.2022.161084
关键词
Process simulation; Comammox; Nitrospira; Nitrobacter; Two-step nitrification
This study developed an activated sludge model to account for competition between nitrite oxidizing bacteria and comammox bacteria. Experimental data was used for model calibration and validation, and the newly developed model accurately predicted the relative abundance of comammox bacteria and nitrifiers to heterotrophs ratio. The study contributes to a better understanding of autotrophic nitrogen removal processes with nitrite as an intermediate product.
The second step of nitrification can be mediated by nitrite oxidizing bacteria (NOB), i.e. Nitrospira and Nitrobacter, with different characteristics in terms of the r/K theory. In this study, an activated sludge model was developed to account for competition between two groups of canonical NOB and comammox bacteria. Heterotrophic denitrification on soluble microbial products was also incorporated into the model. Four 5-week washout trials were carried out at dissolved oxygen-limited conditions for different temperatures (12 degrees C vs. 20 degrees C) and main substrates (NH4+-N vs. NO2--N). Due to the aggressive reduction of solids retention time (from 4 to 1 d), the biomass concentrations were continuously de-creased and stabilized after two weeks at a level below 400 mg/L. The collected experimental data (N species, biomass concentrations, and microbiological analyses) were used for model calibration and validation. In addition to the standard predictions (N species and biomass), the newly developed model also accurately predicted two microbiological indica-tors, including the relative abundance of comammox bacteria as well as nitrifiers to heterotrophs ratio. Sankey diagrams revealed that the relative contributions of specific microbial groups to N conversion pathways were significantly shifted during the trial. The contribution of comammox did not exceed 5 % in the experiments with both NH4+-N and NO2--N substrates. This study contributes to a better understanding of the novel autotrophic N removal processes (e.g. deammonification) with nitrite as a central intermediate product.
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