NO_2^--N和盐度对反硝化除磷及N_2O释放的影响

Effects of nitrite and salinity on efficiency of denitrification phosphorus removal system and nitrous oxide emissions

以驯化好的反硝化除磷污泥为研究对象,通过批式实验考察了NO_2^--N和NaCl浓度对反硝化除磷率及N_2O释放的影响。当进水亚硝酸盐的浓度由15 mg·L^(-1)升高至25和40 mg·L^(-1)时,除磷率由68.81%±0.5%降至66.25%±1%和62.88%±0.8%,TN的去除率由90.6%±0.7%降至74.55%±1.5%和51.65%±2%,N_2O释放量分别为4.82、13.83和17.06 mg。当NaCl质量分数为0%、0.5%、1%和2%时,TN的去除率由74.55%±1%降至68%±2%、64.2%±1%和54.3%±2.5%,除磷率由66.37%±1.5%降至61.29%±1%、50.47%±2%和36.7%±0.5%,N_2O-N转化率为41.1%±2%、41.4%±2.5%、48.94%±0.6%和51.03%±2%。因此,NO_2^--N和NaCl质量分数的升高均会降低脱氮除磷效率,但增加了N_2O释放量;兼顾脱氮除磷效率前提下,NO_2^--N为25 mg·L^(-1)、NaCl质量分数为1%是N_2O释放量增加的优化条件。

The effects of nitrite and salinity on denitrifying phosphorus removal and nitrous oxide emissions were investigated by batch experiments. When the nitrite concentration increased from 15 to 25 and 40 mg·L^-1, the phosphorus removal efficiency decreased from 68.81% ± 0.5% to 66.25% ± 1% and 62.88% ± 0.8%, and the total nitrogen removal efficiency decreased from 90.6% ± 0.7% to 74.55% ± 1.5% and 51.65% ± 2%. However, the nitrous oxide emissions increased from 8.82 to 13.83 and 17.06 mg, respectively. With the increase of salinity concentration from 0% to 0.5%, 1% and 2%, the total nitrogen removal efficiency decreased from 74.55% ± 1% to 68% ± 2%, 64.2% ± 1% and 54.3% ± 2.5%, and the phosphorus removal rates decreased from 66.37% ± 1.5% to 61.29% ± 1%, 50.47% ± 2% and 36.7% ± 0.5%. Correspondingly, 41.1% ± 1.5%, 41.4% ± 2.5%, 48.94% ± 0.6% and 51.03% ± 2% of the total nitrogen was converted to nitrous oxide, respectively. In summary, the removal efficiency of nitrogen and phosphorus decreased simultaneously with the increase of the nitrite and salinity concentration, while the nitrous oxide emissions increased. Therefore, the optimum condition was when the nitrite and Na Cl concentration were 25 mg·L^-1 and 1%,which was better for both the nitrous oxide accumulation and the nitrogen and phosphate removal.