Keithley Asher E, Gomez-Alvarez Vicente, Williams Daniel, Ryu Hodon, Lytle Darren A
U.S. Environmental Protection Agency, ORD, CESER, WID, Cincinnati, OH 45268, United States.
J Water Process Eng. 2023 Dec;56:1-11. doi: 10.1016/j.jwpe.2023.104360.
The biological treatment process consisting of an aerated contactor and filter is effective for groundwaters containing elevated ammonia and other reduced contaminants, including iron, manganese, arsenic, and methane. Depth profiles characterizing microbial activity across aerated contactors are lacking. A 1-year pilot study comparing gravel- and ceramic-packed contactors was conducted, and media depth profile samples were collected at the conclusion of the study. Media and water samples also were collected from pilot-scale aerated contactors at 4 other water systems. Water quality, media surface metals concentrations, and a suite of biofilm parameters were analyzed. Media surface metals concentrations were greatest at the influent end. ATP concentrations, extracellular polymeric substances, and extracellular enzyme activities tended to be similar across depth. Bacteria and functional genes involved in contaminant oxidation co-occurred and tended to decrease across depth, but were not correlated to the media metals concentration. Microbial community composition changed with depth, and the diversity either decreased or remained similar. The microbial activity profiles through aerated contactors differed from what is typically reported for groundwater biofilters, suggesting that the different reactor flow and dissolved oxygen profiles impacted the microbial community.
由曝气接触器和过滤器组成的生物处理工艺对于含有高浓度氨及其他还原性污染物（包括铁、锰、砷和甲烷）的地下水有效。目前缺乏描述曝气接触器中微生物活性的深度剖面。开展了一项为期1年的中试研究，比较了填充砾石和陶瓷的接触器，并在研究结束时采集了介质深度剖面样本。还从其他4个水系统的中试规模曝气接触器中采集了介质和水样。分析了水质、介质表面金属浓度以及一系列生物膜参数。介质表面金属浓度在进水端最高。ATP浓度、胞外聚合物和胞外酶活性在整个深度上往往相似。参与污染物氧化的细菌和功能基因同时出现，且往往随深度降低，但与介质金属浓度无关。微生物群落组成随深度变化，多样性要么降低，要么保持相似。曝气接触器中的微生物活性剖面与地下水生物滤池的典型报道不同，这表明不同的反应器水流和溶解氧剖面影响了微生物群落。
