Swiss Centre for Applied Ecotoxicology, CH-8600 Dübendorf, CH-1015 Lausanne, Switzerland.
Swiss Centre for Applied Ecotoxicology, CH-8600 Dübendorf, CH-1015 Lausanne, Switzerland.
Water Res. 2022 Apr 1;212:118084. doi: 10.1016/j.watres.2022.118084. Epub 2022 Jan 17.
Micropollutants present in the effluent of wastewater treatment plants (WWTPs) after biological treatment are largely eliminated by effective advanced technologies such as ozonation. Discharge of contaminants into freshwater ecosystems can thus be minimized, while simultaneously protecting drinking water resources. However, ozonation can lead to reactive and potentially toxic transformation products. To remove these, the Swiss Federal Office for the Environment recommends additional "post-treatment" of ozonated WWTP effluent using sand filtration, but other treatments may be similarly effective. In this study, 48 h composite wastewater samples were collected before and after full-scale ozonation, and after post-treatments (full-scale sand filtration, pilot-scale fresh and pre-loaded granular activated carbon, and fixed and moving beds). Ecotoxicological tests were performed to quantify the changes in water quality following different treatment steps. These included standard in vitro bioassays for the detection of endocrine, genotoxic and mutagenic effects, as well as toxicity to green algae and bacteria, and flow-through in vivo bioassays using oligochaetes and early life stages of rainbow trout. Results show that ozonation reduced a number of ecotoxicological effects of biologically treated wastewater by 66 - 93%: It improved growth and photosynthesis of green algae, decreased toxicity to luminescent bacteria, reduced concentrations of hormonally active contaminants and significantly changed expression of biomarker genes in rainbow trout liver. Bioassay results showed that ozonation did not produce problematic levels of reaction products overall. Small increases in toxicity observed in a few samples were reduced or eliminated by post-treatments. However, only relatively fresh granular activated carbon (analyzed at 13,000 - 20,000 bed volumes) significantly reduced effects additionally (by up to 66%) compared to ozonation alone. Inhibition of algal photosynthesis, rainbow trout liver histopathology and biomarker gene expression proved to be sufficiently sensitive endpoints to detect the change in water quality achieved by post-treatment.
经生物处理后的废水处理厂（WWTP）废水中存在的微量污染物，可通过臭氧化等有效先进技术基本去除。因此，可以最大限度地减少污染物排放到淡水生态系统中，同时保护饮用水资源。然而，臭氧化会导致反应性和潜在毒性的转化产物。为了去除这些物质，瑞士联邦环境局建议对臭氧化的 WWTP 废水进行额外的“后处理”，使用砂滤，但其他处理方法可能同样有效。在这项研究中，在全规模臭氧化前后以及后处理（全规模砂滤、中试新鲜和预加载颗粒活性炭以及固定和移动床）后，收集了 48 小时的复合废水样品。进行了生态毒理学测试，以量化不同处理步骤后水质的变化。这些测试包括用于检测内分泌、遗传毒性和致突变性影响的标准体外生物测定，以及使用寡毛类动物和虹鳟鱼早期生命阶段的流动体内生物测定，用于检测藻类和细菌的毒性。结果表明，臭氧化将生物处理废水的许多生态毒性作用降低了 66-93%：它改善了绿藻的生长和光合作用，降低了对发光细菌的毒性，减少了激素活性污染物的浓度，并显著改变了虹鳟鱼肝脏中的生物标志物基因的表达。生物测定结果表明，臭氧化总体上不会产生有问题的反应产物水平。在少数几个样本中观察到的毒性增加在经过后处理后减少或消除。然而，只有相对新鲜的颗粒活性炭（在 13,000-20,000 床体积时进行分析）与单独臭氧化相比，还能显著降低（高达 66%）其他影响。藻类光合作用抑制、虹鳟鱼肝组织病理学和生物标志物基因表达被证明是足够敏感的终点，可以检测到后处理所达到的水质变化。
