不同电子受体反硝化过程中C/N对N2O产量的影响

试验采用SBR反应器，分别考察了不同C/N条件下，以硝酸盐和亚硝酸盐为电子受体的反硝化过程中N₂O产生情况.投加乙醇作为反硝化碳源，以硝酸盐为电子受体时调节C/N分别为0、 1.2、 2.4、 3.5、 5.0和20，以亚硝酸盐为电子受体时调节C/N分别为0、 1.8、 2.4、 3.0、 4.3、 5.2、 6.6和20.6.结果发现，以亚硝酸盐为电子受体时，最佳C/N为3.0，此时N₂O产生量为0.044 mg·L^－１；以硝酸盐为电子受体时，最佳C/N为5.0，此时N₂O产生量为0.135 mg·L^－１，是以亚硝酸盐为电子受体时的3倍.电子受体类型不同时，N₂O产生量的变化趋势类似：在碳源严重不足时，反硝化率和N₂O产生量均很低；碳源相对不足时N₂O产生量增加；C/N过大时，虽然反硝化速率很快，但N₂O产量也急剧增大.可见，与全程硝化反硝化工艺相比，短程硝化反硝化工艺可节省40%碳源，且控制C/N=3，其反硝化过程产生的N₂O远少于全程反硝化.

Effect of C/N Ratio on Nitrous Oxide Production During Denitrification with Different Electron Acceptors

The experiment investigated the nitrous oxide production under different C/N ratios during denitrification, taking nitrate and nitrite as electron acceptor respectively. Ethanol was selected as carbon source. The C/N ratios were 0, 1.2, 2.4, 3.5, 5.0 and 20 when nitrate was taken as electron acceptor and C/N ratios 0, 1.8, 2.4, 3.0, 4.3, 5.2, 6.6, 20.6 when electron acceptor was nitrite. The results indicated that: the optimum C/N ratio was 3.0 taking nitrite as electron acceptor and the N_2O production was 0.044 mg·L~(-1) ;the optimum C/N ratio was 5.0 taking nitrate as electron acceptor and the N_2O production was 0.135 mg-L~(-1) which was 3 times higher than that of nitrite as electron acceptor. Though the electron acceptor changed, the trend of N_2O production was similar: when carbon source was badly insufficient, the production of N_2O and denitrification rate were both quite small; the N_2O production increased with the increasing of the quantity of carbon source; when the carbon source was excessive, the N_2O production sharply raised. Consequently, compared to complete nitrification and denitrification, short-cut nitrification and denitrification could save 40% carbon source. Moreover, controlling C/N = 3 could reduce the production of N_2O in short-cut nitrification.