Department of Civil Engineering, University of Idaho, PO Box 441022, Moscow, ID 83844-1022, USA.
Water Res. 2011 Nov 15;45(18):6119-30. doi: 10.1016/j.watres.2011.09.006. Epub 2011 Sep 14.
The objective of this research was to advance a fundamental understanding of a unique post-anoxic denitrification process for achieving biological nutrient removal (BNR), with an emphasis on elucidating the impacts of surface oxygen transfer (SOT), variable process loadings, and bioreactor operational conditions on nitrogen and phosphorus removal. Two sequencing batch reactors (SBRs) were operated in an anaerobic/aerobic/anoxic mode for over 250 days and fed real municipal wastewater. One SBR was operated with a headspace open to the atmosphere, while the other had a covered liquid surface to prevent surface oxygen transfer. Process performance was assessed for mixed volatile fatty acid (VFA) and acetate-dominated substrate, as well as daily/seasonal variance in influent phosphorus and ammonia loadings. Results demonstrated that post-anoxic BNR can achieve near-complete (>99%) inorganic nitrogen and phosphorus removal, with soluble effluent concentrations less than 1.0 mgN L(-1) and 0.14 mgP L(-1). Observed specific denitrification rates were in excess of typical endogenous values and exhibited a linear dependence on the glycogen concentration in the biomass. Preventing SOT improved nitrogen removal but had little impact on phosphorus removal under normal loading conditions. However, during periods of low influent ammonia, the covered reactor maintained phosphorus removal performance and showed a greater relative abundance of polyphosphate accumulating organisms (PAOs) as evidenced by quantitative real-time PCR (qPCR). While GAOs were detected in both reactors under all operational conditions, BNR performance was not adversely impacted. Finally, secondary phosphorus release during the post-anoxic period was minimal and only occurred if nitrate/nitrite were depleted post-anoxically.
本研究旨在深入了解一种独特的缺氧后反硝化工艺，以实现生物营养素去除（BNR），重点阐明表面氧转移（SOT）、可变工艺负荷和生物反应器操作条件对氮和磷去除的影响。两个序批式反应器（SBR）在厌氧/好氧/缺氧模式下运行超过 250 天，并以实际城市废水为处理对象。一个 SBR 的顶部空间与大气相通，而另一个则采用覆盖液面的方式防止表面氧转移。评估了混合挥发性脂肪酸（VFA）和乙酸盐为主的基质以及进水磷和氨负荷的日/季节变化对工艺性能的影响。结果表明，缺氧后反硝化可以实现近完全（>99%）的无机氮和磷去除，出水可溶性浓度小于 1.0 mgN L(-1) 和 0.14 mgP L(-1)。观察到的特定反硝化速率超过典型的内源性值，并与生物量中的糖原浓度呈线性关系。在正常负荷条件下，防止 SOT 可以提高氮去除率，但对磷去除影响不大。然而，在进水氨浓度较低的时期，覆盖式反应器保持了磷去除性能，并通过定量实时 PCR（qPCR）显示出更多的聚磷菌（PAOs）相对丰度。在所有操作条件下，两个反应器中均检测到 GAOs，但 BNR 性能未受到不利影响。最后，缺氧后阶段的二次磷释放量很小，只有在缺氧后硝态氮/亚硝态氮耗尽时才会发生。
