城市污水管网中不同生化作用的基质流向

为研究城市污水管网中有机污染物在生物代谢反应过程中的利用机制,通过运行以实际管网沉积物为底物和以人工配置沉积物为底物的不同模拟条件下的污水管网中试系统,对比分析了管网中污水与沉积物之间COD、甲烷、硝态氮和硫酸根的迁移转化特性.结果表明,污水在模拟管网中流动一周期内,污水中COD的总变化量为170.58 mg·L~(-1),其中,由沉积作用导致COD的变化量为101.53 mg·L~(-1),由生化作用导致COD的变化量为69.05 mg·L~(-1).同时,在微生物的代谢作用下,管网甲烷产量为7.39 mg·L~(-1);污水中硝态氮减少量为0.33 mg·L~(-1);硫酸根减少量为21.35 mg·L~(-1),依据公式推算,在污水管网运行过程中,发酵产甲烷过程消耗的COD为32.51 mg·L~(-1);反硝化作用消耗的COD为8.04 mg·L~(-1);硫酸盐还原菌还原硫酸盐消耗的COD为6.41 mg·L~(-1).由此可知,沉积作用导致的COD变化量占COD总变化量的65.38%;生化作用导致的COD变化量占COD总变化量的34.62%,而发酵产甲烷、反硝化作用和硫酸盐还原菌还原硫酸盐这三项生化代谢作用消耗的COD共占生化作用降解COD的68.01%,该结果表明,沉积作用是污水管网中有机污染物去除的主要方式,而发酵产甲烷、反硝化作用和硫酸盐还原菌还原硫酸根是管网中生化作用去除有机污染物的重要过程.

Substrate Flow by Different Biochemical Activities in the Urban Sewage Network

In order to investigate the consumption mechanism of organic contaminants in different biological metabolism pathways within an urban sewage network, a pilot-scale system using two kinds of sediments (urban sewage sediment and artificial sediment) was constructed. The pilot system was operated to study the migration and transformation characteristics of COD, methane, nitrate, and sulfate between sediment and sewage. Results showed that the variation of COD in sewage was 170.58 mg·L^-1, with change of COD by deposition and bioreaction of 101.53 mg·L^-1 and 69.05 mg·L^-1, respectively. Due to biological metabolism, the generation of methane in sewers was of 7.39 mg·L^-1; the decrease of nitrate and sulfate in sewage was 0.33 mg·L^-1 and 21.35 mg·L^-1, respectively. Based on our calculations, the consuming concentration of COD was 32.51 mg·L^-1for methane generation, 8.04 mg·L^-1 for denitrification, and 6.41 mg·L^-1for sulfate degradation by sulfate reducing bacteria. The decrease in COD by deposition was responsible for 65.38% of total variation of COD in sewage. The decrease in COD by bioreaction was responsible for 34.62% of total variation in COD. Meanwhile, total variation values of COD for methane generation, denitrification, and sulfate degradation were responsible for 68.01% of COD variation by bioreaction. Deposition was therefore the main pathway for removal of organic contaminants from the sewer system; biochemical activities of methane generation, denitrification, and sulfate degradation also played important roles.