盐度抑制下的MUCT处理效能及其微生物种群变化

Salt Effects on Treatment Performance and Microbial Community Structure in MUCT

研究盐度对活性污泥处理系统及其处理效能的影响,对生物处理含盐污水工程的设计与实施具有重要意义.本试验采用MUCT工艺处理含盐生活污水,在淡水以及5、8、10和15g/L等不同NaCl盐度水平下,研究了盐度对生物处理的综合影响.结果表明,相对有机物而言,盐度对营养污染物去除抑制更强烈.当进水盐度超过8g/L后,MUCT总磷去除率从淡水的92%下降到72%,总氮的去除效率从75%下降到62%.当盐度超过15g/L,好氧异养菌数量开始减少,导致有机物去除率的下降.在盐度的抑制下,强化生物除磷系统的特异反应表现为:①当盐度超过8g/L,好氧池内发生了显著的亚硝酸积累(超过80%的积累率).高亚硝酸盐积累刺激了反硝化亚硝酸盐吸磷的发生;②随着盐度的升高,厌氧放磷消耗的有机物量逐渐提高.试验进一步研究了盐度影响下微生物种群结构的变化,为理解盐度影响的本质提供了依据.

It is essential for a full-scale treatment plant processing saline wastewater to understand the effects of salt on an activated sludge system and the performance of pollutant removal. For this purpose, a bench-scale modified university of cape town （MUCT） process was tested to treat real saline sewage with salt concentrations of 5, 8, 10 and 15 g/L. The experimental results indicated that salt in sewage significantly affected nutr/ent removal compared with organic removal. Total phosphorous removal efficiency in MUCT deceased from 92% when treating freshwater to 72% when treating 8 g/L saline wastewater, while total nitrogen removal efficiency decreased from 75% to 62%. Vital number of aerobic heterotrophic bacteria shrunk when salt concentration in wastewater was over 15 g/L, resulting in decreased organic removal efficiency. Obvious nitrite accumulation in the aerobic tank and denitrifying nitrite by polyphosphate accumulating organisms （PAOs） in the anoxic tank occurred in the MUCT treating saline sewage containing over 8 g/L NaCI. Elevated salt level enhanced the carbon requirement for phosphorus release. Population shift in biological community （aerobic-heterotrophic, nitrifying, and denitrifying organisms） in treatment system was observed in response to salinity inhibition, which contributed to an insight into the nature and the magnitude of the salt effects.