两种典型PPCPs在潜流人工湿地中的季节性去除效果及降解产物

Seasonal Removal Efficiency and Degradation Products of Two Typical PPCPs in Subsurface Flow Constructed Wetlands

药物及个人护理品(PPCPs)在地表水中的污染问题已引起了广泛关注,人工湿地(constructed wetlands,CWs)在PPCPs去除中具有突出优势,然而关于不同类型PPCPs在CWs去除中的相互作用研究得还较少.本研究选取两种常用且相对分子质量接近的典型PPCPs——广谱抗菌剂三氯生(TCS)和非甾体抗炎药物双氯芬酸(DCF)作为目标污染物,分析其在潜流人工湿地中的去除行为,并探讨不同季节和不同进水条件(TCS、DCF单独投加和二者复合投加)对两种污染物去除效果的影响.人工湿地系统的主要参数如下:上行流式潜流人工湿地,水力负荷为0.20 m·d^(-1),水力停留时间为3 d,进水方式采用连续流进水.PPCPs初始进水浓度为TCS 80μg·L^(-1)和DCF 25μg·L^(-1).结果表明,TCS和DCF在夏季平均去除率(分别为91.72%和85.86%)均显著高于冬季(分别为52.88%和32.47%).独立样本t检验证实,不同进水条件(TCS、DCF两者单独投加和二者复合投加)下,TCS和DCF的去除效果无显著差异.同时,TCS和DCF的降解产物在不同进水系统中没有差异,其中TCS在不同系统中均未检测到代表性降解产物,DCF在不同系统中主要降解产物均为3,5-二氯苯甲酸和间二氯苯,两种典型PPCPs在微量(μg·L^(-1))层级上无显著拮抗、竞争等相互作用.

The pollution of surface waters by pharmaceuticals and personal care products(PPCPs)has aroused widespread concern.Constructed wetlands(CWs)have outstanding advantages in the removal of PPCPs;however,few studies have focused on the interaction of different types of PPCPs in CWs.In this study,two typical PPCPs[broad-spectrum antimicrobial agents triclosan(TCS)and non-steroidal anti-inflammatory drug diclofenac(DCF)]were selected as target pollutants and their removal behavior in subsurface flow CWs was analyzed.The effects of different seasons and influent conditions(i.e.,single and combined addition of TCS and DCF)on removal efficiency was also examined.The main parameters of the CW system were as follows:the up-flow subsurface CW had a hydraulic load of 0.20 m·d^(-1)and a hydraulic residence time of 3 d with a continuous flow inlet.The initial influent concentration of PPCPs was 80 g·L^(-1)for TCS and 25 g·L^(-1)for DCF.The results showed that the average removal efficiencies for TCS and DCF in summer(91.72%and 85.86%,respectively)were significantly higher than in winter(52.88%and 32.47%,respectively).Independent sample t-tests confirmed that there was no significant difference in the removal efficiency of TCS and DCF under the different influent conditions(single and combined addition).The degradation products of TCS and DCF were also no different between the influent systems,and the representative degradation products of TCS were not detected in all systems.The main degradation products of DCF in the different systems were 3,5-dichlorobenzoic acid and m-dichlorobenzene.The two studied PPCPs showed no significant antagonism and competition effects at trace levels.