GEMMA-Group of Environmental Engineering and Microbiology, Department of Hydraulic, Maritime and Environmental Engineering, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona, Spain.
Water Res. 2013 Jan 1;47(1):315-25. doi: 10.1016/j.watres.2012.10.005. Epub 2012 Oct 23.
This study aimed at assessing the influence of primary treatment (hydrolytic upflow sludge blanket (HUSB) reactor vs. conventional settling) and operational strategy (alternation of saturated/unsaturated phases vs. permanently saturated) on the removal of various emerging organic contaminants (i.e. ibuprofen, diclofenac, acetaminophen, tonalide, oxybenzone, bisphenol A) in horizontal subsurface flow constructed wetlands. For that purpose, a continuous injection experiment was carried out in an experimental treatment plant for 26 days. The plant had 3 treatment lines: a control line (settler-wetland permanently saturated), a batch line (settler-wetland operated with saturate/unsaturated phases) and an anaerobic line (HUSB reactor-wetland permanently saturated). In each line, wetlands had a surface area of 2.95 m(2), a water depth of 25 cm and a granular medium D(60) = 7.3 mm, and were planted with common reed. During the study period the wetlands were operated at a hydraulic and organic load of 25 mm/d and about 4.7 g BOD/m(2)d, respectively. The injection experiment delivered very robust results that show how the occurrence of higher redox potentials within the wetland bed promotes the elimination of conventional quality parameters as well as emerging microcontaminants. Overall, removal efficiencies were always greater for the batch line than for the control and anaerobic lines, and to this respect statistically significantly differences were found for ibuprofen, diclofenac, oxybenzone and bisphenol A. As an example, ibuprofen, whose major removal mechanism has been reported to be biodegradation under aerobic conditions, showed a higher removal in the batch line (85%) than in the control (63%) and anaerobic (52%) lines. Bisphenol A showed also a great dependence on the redox status of the wetlands, finding an 89% removal rate for the batch line, as opposed to the control and anaerobic lines (79 and 65%, respectively). Furthermore, diclofenac showed a greater removal under a higher redox status (70, 48 and 32% in the batch, control and anaerobic lines). Average removal efficiencies of acetaminophen, oxybenzone and tonalide were almost >90% for the 3 treatment lines. The results of this study indicate that the efficiency of horizontal flow constructed wetland systems can be improved by using a batch operation strategy. Furthermore, we tentatively identified 4-hydroxy-diclofenac and carboxy-bisphenol A as intermediate degradation products. The higher abundance of the latter under the batch operation strategy reinforced biodegradation as a relevant bisphenol A removal pathway under higher redox conditions.
本研究旨在评估初级处理（水解上流污泥床（HUSB）反应器与传统沉淀）和操作策略（饱和/不饱和阶段交替与永久饱和）对水平潜流人工湿地中各种新兴有机污染物（即布洛芬、双氯芬酸、对乙酰氨基酚、邻苯二甲酸酯、氧苯酮、双酚 A）去除的影响。为此，在一个实验性处理厂中进行了为期 26 天的连续注入实验。该工厂有 3 条处理线：一条对照线（沉淀湿地永久饱和）、一条间歇线（沉淀湿地采用饱和/不饱和阶段操作）和一条厌氧线（HUSB 反应器-湿地永久饱和）。在每条线上，湿地的表面积为 2.95 m(2)，水深为 25 cm，颗粒介质 D(60)为 7.3 mm，并种植了普通芦苇。在研究期间，湿地的水力和有机负荷分别为 25 mm/d 和约 4.7 g BOD/m(2)d。注入实验产生了非常可靠的结果，表明湿地床内更高的氧化还原电位如何促进常规质量参数以及新兴微污染物的消除。总体而言，间歇线的去除效率始终高于对照线和厌氧线，在这方面，布洛芬、双氯芬酸、氧苯酮和双酚 A 的去除效率存在统计学上的显著差异。例如，布洛芬的主要去除机制据报道是在好氧条件下的生物降解，其在间歇线（85%）的去除率高于对照线（63%）和厌氧线（52%）。双酚 A 也显示出对湿地氧化还原状态的强烈依赖性，在间歇线中发现 89%的去除率，而在对照线和厌氧线中分别为 79%和 65%。此外，双氯芬酸在更高的氧化还原状态下有更大的去除（间歇线、对照线和厌氧线分别为 70%、48%和 32%）。3 条处理线对乙酰氨基酚、氧苯酮和邻苯二甲酸酯的平均去除效率均接近 90%。本研究结果表明，通过采用间歇操作策略，可以提高水平流人工湿地系统的效率。此外，我们初步确定了 4-羟基-双氯芬酸和羧基双酚 A 作为中间降解产物。在间歇操作策略下，后者的丰度更高，这强化了在更高氧化还原条件下生物降解作为双酚 A 去除途径的重要性。
