亚硝酸盐占比对反硝化及N_(2)O释放的影响

Effect of the proportion of nitrite on denitrification and N_(2)O release

针对反硝化过程中N_(2)O大量释放这一问题,研究了不同NO_(2)^(-)-N占比对反硝化脱氮过程及N_(2)O释放的影响。在保证初始氮素浓度总和为100 mg·L^(−1)的条件下,改变NO_(2)^(-)-N所占比例进行批次实验,分别考察了反应器的脱氮速率及氮素指标变化。结果表明,随着初始NO_(2)^(-)-N占比的升高,反硝化脱氮效率升高。其中,NO_(2)^(-)-N浓度随时间基本呈先升高后降低的趋势。初始NO_(2)^(-)-N占比越高,NO3--N降解速率越快,NO_(2)^(-)-N积累也越多。随着NO_(2)^(-)-N占比的升高,N_(2)O的积累速率、积累最高值和转化率均逐渐增大,最高分别为18.828 mg·(g·h)^(-1)、22.123 mg·L^(−1)和24.05%。随着初始NO_(2)^(-)-N占比的升高,游离亚硝酸(free nitrous acid,FNA)浓度也随之升高,从而导致N_(2)O产生大量积累。

Aiming at the problem of large amount of N_(2)O release during sewage treatment,the effects of different NO_(2)^(-)-N ratios on the denitrification process and N_(2)O release were studied.At the total nitrogen concentration of 100 mg·L^(−1),the change of NO_(2)^(-)-N proportion was performed to conduct batch experiment.The reactor denitrification rate and nitrogen index variations were studied.The results show that the denitrification efficiency increased with the increase of the initial NO_(2)^(-)-N ratio,in which the NO_(2)^(-)-N concentration basically increased first and then decreased.The higher the initial NO_(2)^(-)-N ratio,the faster the degradation rate of NO3--N and the more NO_(2)^(-)-N accumulation.With the increase of the initial NO_(2)^(-)-N ratio,the accumulation rate,maximum accumulation value and conversion rate of N_(2)O both gradually increased.The highest values were18.828 mg·(g·h)^(-1),22.123 mg·L^(−1)and 24.05%,respectively.As the initial NO_(2)^(-)-N ratio increased,the concentration of free nitrous acid(FNA)increased,resulting in more N_(2)O accumulation.FNA concentration may be the cause of the large N_(2)O accumulation.