Wantawin C, Juateea J, Noophan P L, Munakata-Marr J
Department of Environmental Engineering, Faculty of Engineering, King Mongkut's University of Technology, Thonburi, Bangkok 10140, Thailand.
Water Sci Technol. 2008;58(10):1889-94. doi: 10.2166/wst.2008.527.
Conventional nitrification-denitrification treatment is a common way to treat nitrogen in wastewater, but this process is costly for low COD/N wastewaters due to the addition of air and external carbon-source. However, ammonia may alternatively be converted to dinitrogen gas by autotrophic bacteria utilizing aerobically autotrophically produced nitrite as an electron acceptor under anoxic conditions. Lab-scale sequencing batch biofilm reactors (SBBRs) inoculated with normal nitrifying sludge were employed to study the potential of an oxygen-limited autotrophic nitrification-denitrification process initiated with typical nitrifying sludge for treating a synthetic ammonia wastewater devoid of organic carbon in one step. The ring-laced fibrous carrier (length 0.32 m, surface area 3.4 m2/m) was fixed vertically in a 3 L reactor. Two different air supply modes were applied:continuous aeration to control dissolved oxygen at 1.5 mg/L and intermittent aeration. High nitrogen removals of more than 50% were obtained in both SBBRs. At an ammonia loading of 0.882 gm N/m2-day [hydraulic retention time (HRT) of 24 hr], the SBBR continuously aerated to 1.5 mg DO/L had slightly higher nitrogen removal (64%) than the intermittently alternated SBBR (55%). The main form of residual nitrogen in the effluent was ammonia, at concentrations of 25 mg/L and 37 mg N/L in continuous and intermittent aeration SBBRs, respectively. Ammonia was completely consumed when ammonia loading was reduced to 0.441 gm N/m2-day [HRT extended to 48 hr]. The competitive use of nitrite by aerobic nitrite oxidizing bacteria (ANOB) with anaerobic ammonia-oxidizing bacteria (anammox bacteria) during the expanded aeration period under low remaining ammonia concentration resulted in higher nitrate production and lower nitrogen loss in the continuous aeration SBBR than in the intermittent aeration SBBR. The nitrogen removal efficiencies in SBBRs with continuous and alternating aerated were 80% and 86% respectively. Specific microorganisms in the biofilm were characterized using fluorescence in situ hybridization. Aerobic ammonia-oxidizing bacteria (AAOB) occurred side by side with putative anammox bacteria (cells hybridizing with probe AMX820) throughout the biofilm, though ANOB were rarely detected.
传统的硝化-反硝化处理是处理废水中氮的常用方法，但由于需要曝气和添加外部碳源，该过程对于低化学需氧量/氮（COD/N）的废水成本较高。然而，在缺氧条件下，自养细菌可以利用好氧自养产生的亚硝酸盐作为电子受体，将氨转化为氮气。本研究采用接种普通硝化污泥的实验室规模序批式生物膜反应器（SBBR），研究以典型硝化污泥启动的限氧自养硝化-反硝化工艺一步处理无有机碳合成氨废水的潜力。将环状纤维载体（长度0.32 m，表面积3.4 m2/m）垂直固定在3 L反应器中。采用两种不同的曝气方式：连续曝气以控制溶解氧为1.5 mg/L和间歇曝气。两个SBBR的氮去除率均超过50%。在氨负荷为0.882 g N/m2·天[水力停留时间（HRT）为24小时]时，连续曝气至1.5 mg DO/L的SBBR的氮去除率（64%）略高于间歇曝气的SBBR（55%）。出水残余氮的主要形式是氨，连续曝气和间歇曝气SBBR中的氨浓度分别为25 mg/L和37 mg N/L。当氨负荷降至0.441 g N/m2·天[HRT延长至48小时]时，氨被完全消耗。在低剩余氨浓度下的曝气扩展期，好氧亚硝酸盐氧化细菌（ANOB）与厌氧氨氧化细菌（厌氧氨氧化菌）对亚硝酸盐的竞争性利用导致连续曝气SBBR中的硝酸盐产量更高，氮损失更低。连续曝气和交替曝气SBBR的氮去除效率分别为80%和86%。利用荧光原位杂交技术对生物膜中的特定微生物进行了表征。在整个生物膜中，好氧氨氧化细菌（AAOB）与假定的厌氧氨氧化菌（与探针AMX820杂交的细胞）并存，尽管很少检测到ANOB。
