Pintar Katarina D M, Slawson Robin M
NSERC Industrial Research Chair in Water Treatment, Department of Civil Engineering, University of Waterloo, 200 University Avenue West, Ont., Canada N2L 3G1.
Water Res. 2003 Apr;37(8):1805-17. doi: 10.1016/S0043-1354(02)00538-9.
The establishment of ammonia-oxidizing bacteria (AOB), a group of autotrophic microorganisms responsible for nitrification in chloraminated distribution systems, was studied in a bench-scale distribution system. The potential significance of temperature and disinfectant residual associated with chloramination in full-scale drinking water distribution systems was assessed. Biofilm development was primarily monitored using AOB abundance and nitrite concentrations. The bench-scale system was initially operated under typical North American summer (22 degrees C) and fall (12 degrees C) temperatures, representing optimal and less optimal growth ranges for these microorganisms. Additional experimentation investigated AOB establishment at a suboptimal winter distribution system temperature of 6 degrees C. The effect of chloramine residual on AOB establishment was studied at higher (0.2-0.6mg/L) and lower (0.05-0.1mg/L) ranges, using a 3:1 (w/w) chlorine:ammonia dosing ratio. Conditions were selected to represent those typically found in a North American distribution system, in areas of low flow and longer retention times, respectively. Finally, the effect of a free chlorine residual on an established nitrifying biofilm was briefly examined. Results clearly indicate that AOB development occurs at all examined temperatures, as well as at selected monochloramine residuals. The maintenance of a disinfectant residual was difficult at times, but was more inhibitory to the nitrifying biofilm than the lower temperature. It can be concluded from the data that nitrification may not be adequately inhibited during the winter months, which may result in more advanced stages of nitrification the following season. Free chlorination can be effective in controlling AOB activity in the short term, but may not prevent reestablishment of a nitrifying biofilm upon return to chloramination.
在一个实验室规模的配水系统中，对氨氧化细菌（AOB）的建立进行了研究。氨氧化细菌是一类自养微生物，负责含氯胺配水系统中的硝化作用。评估了与全尺寸饮用水配水系统中氯胺化相关的温度和消毒剂残留的潜在意义。主要通过AOB丰度和亚硝酸盐浓度来监测生物膜的形成。该实验室规模的系统最初在典型的北美夏季（22摄氏度）和秋季（12摄氏度）温度下运行，分别代表这些微生物的最佳和次佳生长范围。额外的实验研究了在6摄氏度的次优冬季配水系统温度下AOB的建立情况。使用3:1（重量/重量）的氯：氨投加比例，研究了较高（0.2 - 0.6mg/L）和较低（0.05 - 0.1mg/L）范围内氯胺残留对AOB建立的影响。选择这些条件分别代表北美配水系统中低流量和较长停留时间区域通常存在的情况。最后，简要研究了游离氯残留对已建立的硝化生物膜的影响。结果清楚地表明，在所有检测温度以及选定的一氯胺残留水平下，AOB都能生长。有时维持消毒剂残留很困难，但与较低温度相比，其对硝化生物膜的抑制作用更强。从数据可以得出结论，在冬季月份硝化作用可能无法得到充分抑制，这可能导致下一季硝化作用进入更高级阶段。自由氯化在短期内可以有效控制AOB活性，但在恢复氯胺化后可能无法防止硝化生物膜的重新建立。
