Trends in Micropollutant Biotransformation along a Solids Retention Time Gradient
Trends in Micropollutant Biotransformation along a Solids Retention Time Gradient
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DOI：
10.1021/acs.est.8b02763
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发表时间：
2018-10-16
影响因子：
11.4
通讯作者：
Fenner, Kathrin
中科院分区：
文献类型：
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作者：
Achermann, Stefan;Falas, Per;Fenner, Kathrin
对于许多极性有机微污染物，活性污泥微生物的生物转化是废水处理过程中的主要去除过程。然而，我们目前对废水处理操作如何影响微生物群落及其微污染物生物转化潜力的理解是有限的，使得在处理设施中观察到的生物转化率的变化的主要部分无法解释。在这里，我们提出了42个属于不同的化学类微污染物的生物转化速率常数沿着梯度的固体保留时间（SRT）。在两个实验中，生物量标准化一级速率常数的几何平均值显示，SRT 3和15 d之间分别明显增加160%和87%。然而，个别微污染物显示出各种趋势。氧化生物转化反应的速率常数主要随污泥龄的增加而增加。然而，硝化活动可以被排除为主要驱动因素。对于发生氧化反应以外的物质，即，主要是取代型反应，观察到对SRT的更多样化的依赖性。最值得注意的是，观察到的特征趋势组的物质经历类似类型的初始转化反应，这表明，共同调控的酶或酶系统，催化生物转化反应在这样的群体。这些发现开辟了相关的速率常数与酶丰度的措施，如基因或基因产物，这反过来又应该有助于确定与各自的生物转化反应的酶的机会。
For many polar organic micropollutants, biotransformation by activated sludge microorganisms is a major removal process during wastewater treatment. However, our current understanding of how wastewater treatment operations influence microbial communities and their micropollutant biotransformation potential is limited, leaving major parts of observed variability in biotransformation rates across treatment facilities unexplained. Here, we present biotransformation rate constants for 42 micropollutants belonging to different chemical classes along a gradient of solids retention time (SRT). The geometric mean of biomass-normalized first-order rate constants shows a clear increase between 3 and 15 d SRT by 160% and 87%, respectively, in two experiments. However, individual micropollutants show a variety of trends. Rate constants of oxidative biotransformation reactions mostly increased with SRT. Yet, nitrifying activity could be excluded as primary driver. For substances undergoing other than oxidative reactions, i.e., mostly substitution-type reactions, more diverse dependencies on SRT were observed. Most remarkably, characteristic trends were observed for groups of substances undergoing similar types of initial transformation reaction, suggesting that shared enzymes or enzyme systems that are conjointly regulated catalyze biotransformation reactions within such groups. These findings open up opportunities for correlating rate constants with measures of enzyme abundance such as genes or gene products, which in turn should help to identify enzymes associated with the respective biotransformation reactions.