KONGHai-xia,LINLi,LüYong-tao,et al.Factors Influencing Nitrous Oxide Enrichment during Nitrite Denitrification under Acidic Conditions[J].China Water & Wastewater,2024,40(23):57-63.
酸性条件下NO2-型反硝化富集N2O的影响因素
- Title:
- Factors Influencing Nitrous Oxide Enrichment during Nitrite Denitrification under Acidic Conditions
- 摘要:
- N2O是潜在的可再生能源，反硝化过程中N2O的富集可为其能源回收提供依据。接种反硝化污泥后，通过降低进水pH至5.0，7.17%的NO2-转化为N2O。在此基础上，利用批式试验分析了酸性条件（pH为5.0~7.0）和NO2-浓度（10~90 mg/L）对反硝化及N2O释放的影响。结果表明，随着pH的降低及游离亚硝酸（FNA）浓度的升高，N2O净产生率均呈先升后降的趋势，当pH为5.8且NO2-浓度为50 mg/L时（FNA为0.84 mg/L），N2O转化率达到最大值42.56%。利用微电极进一步研究发现，在pH为5.5~7.0条件下，N2O的还原速率随pH的降低及FNA浓度的升高呈降低趋势，且当存在FNA时，降低的幅度增大。综上，酸性条件和FNA均能抑制N2O还原酶的活性，且后者是主要抑制剂。因此，过低的pH及过高的FNA浓度抑制了N2O的产生，导致其净产率下降。
- Abstract:
- Nitrous oxide (N2O) represents a promising renewable energy source, and the accumulation of N2O during the denitrification process can serve as a foundation for its energy recovery. Following the inoculation of the denitrifying sludge, 7.17% of nitrite was transformed into N2O by reducing the influent pH to 5.0. Building upon this foundation, the impacts of acidic conditions (pH 5.0-7.0) and nitrite concentration (10-90 mg/L) on denitrification and N2O emissions were systematically evaluated through batch experiments. As pH decreased and free nitrous acid (FNA) increased, the net production rate of N2O initially rose before subsequently declining. At a pH of 5.8 and a nitrite concentration of 50 mg/L (with FNA at 0.84 mg/L), the N2O conversion rate peaked at 42.56%. Subsequent investigations utilizing microelectrodes revealed that the reduction rate of N2O diminished as the decrease of pH and the increase of FNA concentration within the range of pH 5.5 to 7.0, and a more pronounced decrease observed in the presence of FNA. In summary, both acidic conditions and FNA served as inhibitors of N2O reductase activity, with the latter identified as the primary inhibitor. Consequently, excessively low pH and elevated FNA concentration impeded the production of N2O, leading to a reduction in its net production rate.
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