混合碳源浓度对单级好氧生物脱氮除磷的影响

Effect of mixed carbon source concentration on biological nitrogen and phosphorus removal in oxic/extended-idle process

以乙酸钠和丙酸钠1:2混合作为碳源,进水COD浓度分别为200,400,600,800mg/L,研究混合碳源浓度对单级好氧生物脱氮除磷的影响,并通过比较微生物体内储能物质的变化,探讨混合碳源浓度对生物脱氮除磷性能影响的机理.结果表明,当进水磷和氨氮浓度分别为12,30mg/L时,随着进水COD由200增加至800mg/L,磷去除率由39.9%提升至86.4%(氮去除率从13.5%提升至96.4%).进水COD为400mg/L时单位挥发性悬浮固体(VSS)的磷和氮去除量达到最高[分别为(4.31±0.08)和(6.15±0.22)mg/g].当进水COD由200增加至400mg/L时生物除磷活性增强,而COD继续增加会使污泥沉降性能变差,脱氮除磷生物活性降低.好氧吸磷和同步硝化反硝化主要由微生物体内储能物质多β羟基烷酸盐(PHA)驱动,当进水COD为400mg/L时单位VSS消耗的PHA最多.混合碳源浓度通过影响碳源的好氧代谢,使微生物体内储能物质的积累/转化量不同,进而影响系统的脱氮除磷性能.

To study the effect of mixed carbon source concentration on nitrogen （N） and phosphorus （P） removal in the oxic/extended-idle process, four sequencing batch reactors were operated using sodium acetate and sodium propionate with 1：2 hybrid configured influent COD concentrations of 200, 400, 600 and 800mg/L respectively. The variations of intracellular polymers and the metabolic mechanism were investigated. The experimental results showed that with influent P and N concentrations of 12 and 30mg/L respectively, P and total nitrogen （TN） removal efficiencies were respectively promoted from 39.9% and 54.5% to 86.4% and 98.0% with the increase of influent COD from 200 to 800mg/L. The highest N, P removal per unit VSS [（4.314-0.08） and （6.15^-0.22）mg/g] were both detected under influent COD of 400mg/L. P accumulating activity was enhanced when COD rose from 200 to 400mg/L, but the further increase of influent COD would result in deterioration of sludge settling, leading to a compromised biological N and P removal activity. Both aerobic phosphorus uptake and simultaneous nitrification and denitrification were driven by poly-β-hydoxyalkanoate （PHA）, and the largest amount of PHA consumption per unit VSS was observed under influent COD of 400mg/L. The mixed carbon source concentration influenced microbial aerobic metabolism, which resulted in the difference of the accumulation/conversion of intracellular polymers, and thus influenced N and P removal performance.