亚硝酸盐对聚磷菌反硝化除磷代谢及N2O产生的影响

以乙酸钠/丙酸交替为碳源的强化生物除磷(enhance biological phosphorus removal, EBPR)系统为研究对象,母反应器内种泥在厌氧/好氧的运行条件下已培养340 d,聚磷菌富集纯度达到92%±3%,考察了不同浓度亚硝酸盐氮(44.64、70.3、94.33、112.36 mg NO₂^--N·L^-1)为电子受体对聚磷菌缺氧吸磷代谢的影响。结果表明,从未经缺氧驯化的高纯度聚磷菌也可以进行反硝化除磷代谢。在缺氧反应过程中NO₂^--N还原速率、PO₄^3--P吸收速率、PHA降解速率随着亚硝酸浓度升高呈下降趋势,但是在初始亚硝酸盐氮浓度最高为112.36 mg NO₂^--N·L^-1条件下,代谢并未停止,此时亚硝酸盐还原速率与磷酸盐吸收速率仍可以分别达到2.61 mg NO₂^--N·(g MLSS)^-1·h^-1和3.0 mg PO₄^3--P·(g MLSS)^-1·h^-1。聚磷菌在以细胞内PHA作为碳源以NO₂^--N作为电子受体反硝化除磷代谢过程中,由于初始亚硝酸盐的抑制作用使NO₂^--N还原速率大于N₂O还原速率,从而产生大量的N₂O积累。初始投加NO₂^--N浓度为44.64、70.3、94.33、112.36 mg NO₂^--N·L^-1时,产生的N₂O占TN的比例分别为63.5%、49.0%、30.2%、24.0%。在底物充足的条件下,代谢中积累的N₂O可以通过延长缺氧搅拌时间,使其转化为N₂。

Effect of nitrite on denitrifying phosphorous removal metabolism and N2O production by PAOs

The impact of nitrite (44.64, 70.3, 94.33, 112.36 mg NO₂^--N·L^-1) on denitrifying phosphorus removal metabolism was investigated by using 92%±3% polyphosphate accumulation organisms domesticated in acetate/propionic acid for 340 d.The results showed that denitrifying phosphorus removal metabolism also occurred when nitrite was used as electron acceptor at first, and the metabolism was inhibited when the concentration of nitrite increased.Nitrite reduction rate, phosphorus uptake rate and PHA degradation rate all reduced with initial nitrite increasing, and the complete inhibition concentration was higher than 112.36 mg NO₂^--N·L^-1.Nitrite reduction rate and phosphorus uptake rate were 2.61 mg NO₂^--N·(g MLSS) ^-1·h^-1 and 3.0 mg PO₄^3--P·(g MLSS) ^-1·h^-1 at initial 112.36 mg NO₂^--N·L^-1.N₂O was produced in the denitrifying phosphorus removal process.Initial nitrite stimulated nitrite reduction to exceed N₂O reduction rate, resulting in greater quantities of N₂O production.The proportion of N₂O-N/TN were 63.5%, 49.0%, 30.2%, 24.0% respectively corresponding to initial concentration of 44.64, 70.3, 94.33, 112.36mg NO₂^--N·L^-1.The accumulation of N₂O could be transformed to N₂ in order to improve denitrification when the system had enough substrate and extended anoxic mixing time.