亚硝酸盐对EBPR工艺除磷效率的影响

Effects of nitrite on phosphorus removal rate during EBPR process

[目的]比较亚硝酸盐对不同进水碳源驯化的强化生物除磷(EBPR)污泥除磷活性的抑制作用,分析亚硝酸盐影响EBPR污泥除磷效率的机制。[方法]采用厌氧-好氧型序批式生物反应器(SBR),分别以乙酸(SBR-1)和丙酸(SBR-2)为进水碳源驯化EBPR污泥,待反应器达到稳态运行状态后取1个运行周期,定期取样测定混合液中磷酸根和亚硝氮质量浓度的周期变化,比较亚硝酸盐对2种EBPR污泥除磷活性的影响,测定2种EBPR污泥的脱氮活性;通过研究亚硝酸盐对运行周期中聚磷菌胞内聚羟基烷酸(PHA)和糖原合成与分解代谢的影响,分析亚硝酸盐抑制EBPR除磷活性的机制。[结果]以乙酸为进水碳源的SBR-1和以丙酸为进水碳源的SBR-2分别经过8和11 d的驯化期成功实现了稳定的EBPR功能,除磷效率稳定在98%以上;较高浓度的亚硝酸盐对乙酸驯化的EBPR污泥和丙酸驯化的EBPR污泥均可产生抑制作用,其中以丙酸驯化的EBPR污泥对亚硝酸盐更为敏感,在亚硝氮质量浓度大于或等于5 mg·L^(-1)时即会丧失磷的吸收功能;乙酸驯化的EBPR污泥和丙酸驯化的EBPR污泥均有一定的脱氮能力,以乙酸为碳源驯化而成的EBPR污泥其脱氮活性明显高于丙酸驯化而成的EBPR污泥;在亚硝酸盐抑制除磷活性的同时聚磷菌胞内PHA和糖原代谢也受到明显的抑制作用。[结论]与乙酸驯化的EBPR污泥相比,丙酸驯化的EBPR污泥对亚硝酸盐引起的抑制作用更为敏感,以乙酸为进水碳源有利于EBPR工艺的稳定运行。

[Objectives] Objectives of the present study were to compare the inhibitory effects on phosphorus removal efficiency of enhanced biological phosphorus removal（EBPR） process caused by the presence of nitrite and analyze possible mechanisms involved in nitrite-caused inhibitory effects on EBPR sludge.[Methods] Acclimation of EBPR sludge was carried out in anaerobic-aerobic sequencing batch reactors （SBR） by using acetic acid （SBR-1） and propionic acid （SBR-2） as influent carbon source,respectively.Once steady-state was achieved,a cyclic study for both reactors was initiated through periodic sampling and quantification of phosphate and nitrite in the mixed liquor in the presence of nitrite and a comparative study was conducted on the effects of nitrite on the phosphorus removal efficiency between the two EBPR sludges.Denitrifying activity of both sludges was also determined.Meanwhile,the effects of nitrite on the anabolic and catabolic metabolism of intracellular polyhydroxyalkanoate（PHA） and glycogen were investigated with the purpose of analyzing possible mechanisms involved in nitrite-caused inhibitory effects on EBPR process.[Results] In the present study,enhanced biological phosphorus removal was successfully achieved as indicated by phosphorus removal efficiencies higher than 98% in both acetic acid-fed SBR-1 and propionic acid-fed SBR-2 after an acclimation period of 8 and 11 d,respectively.Introducing nitrite to the mixed liquor led to significant inhibitory on phosphorus removal efficiency of both EBPR sludges.EBPR sludge acclimated with propionic acid in SBR-2 was more sensitive to the toxicity of nitrite than that acclimated with acetic acid in SBR-1 and its phosphorus uptake was completely inhibited due to the presence of a nitrite concentration of 5 mg·L^-1.Although both EBPR sludges showed denitrifying activity from nitrite,significantly higher denitrifying activity was observed in the sludge acclimated with acetic acid as the influent carbon source.Inhibitory effects on the anabolic and catabolic metabolism of intracellular PHA and glycogen were observed in the same range of nitrite concentrations that led to significant inhibition on phosphorus removal for both EBPR sludges.[Conclusions] In comparison to the sludge acclimated with acetic acid as carbon source,EBPR sludge acclimated with propionic acid as carbon source was more sensitive to nitrite-caused inhibition,thus use of acetic acid as influent carbon source would facilitate stable operation of EBPR process.