碳源类型对反硝化除磷过程中N_2O产生的影响机制

以反硝化除磷过程中N2O的减量化为目的,分别以乙酸、乙酸和丙酸的混合物、丙酸为碳源,研究了碳源类型对系统中N2O产生的影响。结果表明:以乙酸为碳源时反硝化除磷过程中N2O的产生量最多,以乙酸和丙酸混合物为碳源时N2O产量次之,以丙酸为碳源时N2O产量最少。使用乙酸、乙酸与丙酸混合物和丙酸为碳源时,N2O产生量占总氮(TN)去除的比例分别为8.67%、1.48%和0.72%。不同碳源导致了系统反硝化进程的不同:以丙酸为碳源时,硝酸盐与亚硝酸盐还原速率比值最低,系统中几乎没有亚硝酸盐的积累;同时,在混合酸和丙酸系统中,聚3-羟基戊酸盐(poly-hydroxyvalerate,PHV)成为聚羟基烷酸酯(poly-β-hydroxyalkanoates,PHA)的主要成分,PHV量的增加导致N2O产量减少。因此,以丙酸作为反硝化除磷系统的外加碳源对N2O的减量化有明显优势,但该过程中系统对氮和磷的去除效果还需要进一步优化。

The mechanism of effect on N2O production of carbon source types in denitrifying phosphorus removal process

In order to reduce the N₂O production in denitrifying phosphorus removal process,the acetate, the mixture of acetate and propionate, and the propionate were used as carbon sources to study their effects on N₂O production in reaction systems. The results showed that in denitrifying phosphorus removal process, the production of N₂O was the most with acetate as carbon source, the second with the mixture of acetate and propionate as carbon source, and the lest with the propionate as carbon source. When use the acetate, the mixture of acetate and propionate, and the propionate as carbon sources, the ratio of N₂O production to the total nitrogen(TN)removal were 8.67%, 1.48% and 0.72% respectively. Different carbon sources resulted in different denitrification process. The ratio of nitrate reduction to nitrite reduction(N1/N2)in propionate system was the lowest, which indicated that there were a few of nitrite accumulated with the propionate as carbon source. At the same time, PHV was the main composition in total PHA in the mixed acid and propionate system. The increasing content of PHV declined the N₂O production. In conclusion, using propionate as carbon source in denitrifying phosphorus removal systems had a significant advantage to reduce the production of N₂O, while the effect of this process on removal of nitrogen and phosphorus still needed to be further optimized.