Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, 1001 South McAllister Avenue, Tempe, AZ 85287-5701, USA.
Water Res. 2010 Mar;44(5):1419-28. doi: 10.1016/j.watres.2009.11.030. Epub 2009 Nov 20.
This study exploited the concept of the minimum/maximum substrate concentrations (MSC values) for identifying proper start-up conditions and achieving stable and low effluent total ammonium nitrogen (TAN) concentrations in suspended-growth short-cut biological nitrogen removal (SSBNR). Calculations based on the MSC concept indicated that S(Dmax), the TAN concentration above which ammonium-oxidizing bacteria (AOB) are washed out, was around 450mgTAN/L at the given operating conditions of 2mg/L of dissolved oxygen and pH 8, while nitrite-oxidizing bacteria (NOB) should be washed out at around 40mgTAN/L. Therefore, the experimental research was focused on the optimal TAN-concentration range for SSBNR, between 50 and 100mg/L. Experimental results showed that a nitrification reactor with initial TAN concentration above 450mg/L did not give a successful start-up. However, two days of starvation, which decreased the TAN concentration in the reactor to 95mg/L, stabilized the reaction quickly, and stable SSBNR was sustained thereafter with 80mgTAN/L and 98% nitrite accumulation in the reactor. During stable SSBNR, the removal ratio of chemical oxygen demand per nitrite nitrogen (DeltaCOD/DeltaNO(2)-N) for denitrification was 1.94gCOD/gN, which is around 55% of that required for nitrate denitrification. Based on a clone library, Nitrosomonas occupied 14% of the total cells, while the sum of Nitrobacter and Nitrospira was less than the detection cut-off of 2%, confirming the NOB were washed out during SSBNR. A spiking test that doubled the influent ammonium loading caused the TAN concentration in the reactor to reach washout for AOB, which lasted until the loading was reduced. Thus, a loading increase should be controlled carefully such that the system does not exceed the washout range for AOB.
本研究利用最小/最大基质浓度 (MSC 值) 的概念来确定适当的启动条件，并在悬浮生长短程生物脱氮 (SSBNR) 中实现稳定和低出水总铵氮 (TAN) 浓度。基于 MSC 概念的计算表明，在给定的操作条件（2mg/L 溶解氧和 pH 值 8）下，当铵氧化菌 (AOB) 被冲洗出时，S(Dmax) 约为 450mgTAN/L，而亚硝酸盐氧化菌 (NOB) 应在 40mgTAN/L 左右被冲洗出。因此，实验研究集中在 SSBNR 的最佳 TAN 浓度范围内，即在 50mg/L 到 100mg/L 之间。实验结果表明，初始 TAN 浓度高于 450mg/L 的硝化反应器无法成功启动。然而，两天的饥饿期使反应器中的 TAN 浓度降低到 95mg/L，使反应迅速稳定下来，此后反应器中维持稳定的 SSBNR，TAN 浓度为 80mg/L，亚硝酸盐积累率为 98%。在稳定的 SSBNR 期间，反硝化的硝态氮（DeltaCOD/DeltaNO(2)-N）去除率为 1.94gCOD/gN，约为硝酸盐反硝化所需的 55%。基于克隆文库，亚硝化单胞菌占总细胞的 14%，而硝化杆菌和硝化螺菌的总和小于检测截止值 2%，证实了在 SSBNR 期间 NOB 被冲洗出。一个两倍于进水氨氮负荷的冲击试验导致反应器中的 TAN 浓度达到 AOB 的冲洗点，直到负荷降低。因此，应小心控制负荷增加，以确保系统不会超过 AOB 的冲洗范围。
