重庆市垃圾处理厂和污水处理厂中典型环境内分泌干扰物的排放特征

石运刚1,刘嘉烈1,唐娜1,马艳2,庄僖2,*,李洁1,郑晶2

1.重庆市固体废物管理中心,重庆 400020

2.生态环境部华南环境科学研究所,国家环境保护环境污染健康风险评价重点实验室,广州510655

摘要:为了研究重庆市典型污染源中酚类环境雌激素(phenolic environmental estrogens,PEEs)和邻苯二甲酸酯(phthalic acid esters,PAEs)的排放特征,评估其对长江水域环境的潜在风险,选取了重庆市人口或工业分布密集、污水排放量大的3家垃圾处理厂和16家污水处理厂作为研究对象,检测了进水和出水中3种PEEs和16种PAEs的浓度,并采用风险商(risk quotient,RQ)法和各物质的雌二醇(estradiol,E2)当量(estradiol equivalent quantity,EEQ)分别评估了出水中主要PEEs和PAEs的生态风险水平和雌激素活性效应。结果表明,在进出水中均检测到3种PEEs和11种PAEs,其中垃圾渗滤液中PEEs(11.07~278.41 μg·L-1)和PAEs(25.83~97.17 μg·L-1)的总浓度最高,工业污水处理厂的进水最低(分别为0.04~13.97 μg·L-1和0.14~4.69 μg·L-1),出水中PEEs和PAEs的浓度相当(分别为0.05~8.96 μg·L-1和1.37~4.19 μg·L-1)。各污染源对辛基酚(4-tert-octylphenol,4-t-OP)和邻苯二甲酸二壬酯(dinonyl phthalate,DNP)的平均去除率达到88%和95%;其中,膜分离技术去除效果最好,活性污泥和氧化沟技术去除率较低。出水中生态风险和雌激素活性最高的化合物均为壬基酚(4-nonylphenol,4-NP),表明4-NP对水环境中的生物存在一定的潜在风险。

关键词:酚类环境雌激素;邻苯二甲酸酯;垃圾处理厂;污水处理厂;排放特征

环境内分泌干扰物(endocrine disrupting compounds,EDCs)对人类健康和水生动物的健康都有重大威胁,因此EDCs的广泛存在引起了人们的高度关注[1-2]。其中,壬基酚(4-NP)、辛基酚(4-t-OP)和双酚A(bisphenol A,BPA)在水环境中具有相似的结构特征和环境行为,被归为酚类环境雌激素(PEEs)[3]。PEEs广泛应用于纺织印花、造纸、颜料合成、石油加工、塑料制造等轻工业和制造业,在个人护理产品和药品中也能检出,因此PEEs在生活中无处不在[4]。邻苯二甲酸酯(PAEs)作为一类人工合成的EDCs,被广泛用于提高塑料的柔韧性,在各种环境中,如大气、水体和土壤样品中均能检测到PAEs的污染[5-6]。研究表明,PEEs和PAEs会引起各种健康问题,包括生殖毒性、出生缺陷、肿瘤的形成、激素水平的改变以及代谢紊乱等[7-8]

PAEs属于半挥发性有机化合物,且不与塑料产品键合,因此,在塑料的生产和使用过程中都可能有PAEs释放进入周围环境[9]。大多数PEEs的复合物在污水处理前或处理过程中,可以通过微生物过程迅速裂解为游离态的PEEs[10]。虽然污水处理厂污水中有机物含量明显降低,但是在最终的出水中仍然广泛检测到PEEs[11-12]和PAEs[13-14],表明污水处理厂的排水可能是环境中这些污染物的来源。另外,垃圾渗滤液是一种含高浓度酚类、PAEs类有机污染物的废水,其中PAEs被列为垃圾渗滤液中的优先污染物[15]。随着城市地区的发展和工业的发展,国内PEEs和PAEs的使用量逐渐增加,其随着生活污水或工业废水排放,对周边水环境的安全构成了潜在威胁。

目前关于PEEs和PAEs在水环境中的赋存和分布研究较多,然而针对这些污染物的来源和排放等相关研究较少。Gao等[16]研究发现,哈尔滨的污水处理厂进水中PAEs的检出率为42%~100%,邻苯二甲酸二(2-乙基)己酯(bis(2-ethylhexyl)phthalate,DEHP)和邻苯二甲酸二丁酯(di-n-butyl phthalate,DnBP)浓度分别高达30.99 μg·L-1和24.46 μg·L-1,污水处理厂对部分PAEs的去除效果有限,意味着污水处理厂排放的废水对其下游的水质有很大影响。重庆市作为中国西部地区唯一的直辖市,人口稠密,经济社会的高速发展为长江水域环境带来风险。最近针对重庆市水环境中PAEs和PEEs污染现状的研究表明,水体中DnBP、邻苯二甲酸二异丁酯(diisobutyl phthalate,DiBP)和DEHP均存在一定程度的潜在生态风险[17],PEEs的主要污染物为4-t-OP、4-NP和BPA,平水期及蓄水期均有雌激素总活性高于1 ng·L-1的点位,提示具有高雌激素活性风险[18]。因此,研究重庆市典型污染源中PEEs和PAEs的排放特征具有重要意义。本研究选取了重庆市的3家垃圾处理厂(waste treatment plants,WTPs)和16家污水处理厂(包括5家生活污水处理厂(domestic sewage treatment plants,DSTPs)、6家工业污水处理厂(industrial sewage treatment plants,ISTPs)和5家混合污水处理厂(mixed sewage treatment plants,MSTPs))作为研究对象,检测了进水和出水中3种PEEs和16种PAEs的浓度,并计算了出水中主要PEEs和PAEs的生态风险水平和雌激素活性效应,以评估其对环境的潜在危害。研究结果为了解重庆市污水处理厂和垃圾处理厂排放PEEs和PAEs的控制与管理提供数据基础。

1 材料与方法(Materials and methods)

1.1 试剂与耗材

3种PEEs标准品和内标(BPA-d16)纯度均>98%,购自美国Supeloco公司和美国剑桥同位素公司(CIL),16种PAEs标准溶液(纯度>95%)和内标DMP-d4和DnOP-d4购自美国AccuStandard公司(表1),甲醇、二氯甲烷和丙酮均为色谱纯,购自上海安谱实验科技股份有限公司。衍生化试剂(BSFFA-TMCS,99∶1)购自日本梯希爱公司,主要耗材有142 mm GF/F、70 mm GF/F滤膜(英国沃特曼公司),HLB固相萃取柱(6 mL,500 mg)(美国Waters公司),0.22 μm有机相针式滤膜(上海安谱实验科技股份有限公司)。

表1 3种环境雌激素(EEs)和16种邻苯二甲酸酯类(PAEs)目标化合物信息
Table 1 General information of three environmental estrogens (EEs) and sixteen phthalate esters (PAEs)

化合物Compounds缩写AbbreviationsCAS号CAS No.PNEC/(μg·L-1)EEF/(×10-5 ng·L-1)方法检出限/(μg·L-1)Method detection limit/(μg·L-1)辛基酚 4-tert-octylphenol4-t-OP140-66-90.122a93 c0.0002壬基酚 4-nonylphenol4-NP104-40-51.12a63c0.0003双酚A Bisphenol ABPA80-05-071.5a11c0.0002邻苯二甲酸二甲酯 Dimethyl phthalateDMP131-11-3960 b0.1 d0.24邻苯二甲酸二乙酯 Diethyl phthalateDEP84-66-273 b0.05 d0.45邻苯二甲酸二异丁酯 Diisobutyl phthalateDiBP84-69-55.4 b0.1 d0.14邻苯二甲酸二丁酯 Di-n-butyl phthalateDnBP84-74-27.0 b0.01 d0.24邻苯二甲酸二(2-乙基)己酯 Bis(2-ethylhexyl)phthalateDEHP117-81-70.72 b2.5 d0.38邻苯二甲酸丁苄酯 Butyl benzyl phthalateBBzP85-68-70.29邻苯二甲酸二正辛酯 Di-n-octyl phthalateDnOP117-84-00.53邻苯二甲酸二甲氧乙酯Bis(2-methoxyethyl) phthalateDMEP117-82-80.17邻苯二甲酸二-4-甲基-2-戊基酯Bis(4-methyl-2-pentyl) phthalateDMPP84-63-90.12邻苯二甲酸双-2-乙氧基乙酯Bis(2-ethoxyethyl) phthalateDEEP605-54-90.16邻苯二甲酸二戊酯 Dipentyl phthalateDPeP131-18-00.34邻苯二甲酸二己酯 Dihexyl phthalateDnHP84-75-30.33邻苯二甲酸二(2-丁氧基)乙酯Bis(2-n-butoxyethyl)phthalateDBEP117-83-90.15邻苯二甲酸二环己酯 Dicyclohexyl phthalateDCHP84-61-70.33邻苯二甲酸二苯酯 Diphenyl phthalateDPhP84-62-80.68邻苯二甲酸二壬酯 Dinonyl phthalateDNP84-76-40.24

注:PNEC表示预测无效应浓度,EEF表示雌二醇当量因子;a此数据来自文献[17],b此数据来自文献[18],c此数据来自文献[19],d此数据来自文献[19]。
Note:PNEC stands for predicted no effect concentration;EEF stands for estradiol equivalent factor;a data from reference [17];b data from reference [18],c data from reference [19];d data from reference [19].

1.2 样品的采集与保存

在筛选生活污水处理厂和垃圾处理厂时,考虑了采样位点的服务人口和服务区域,根据重庆市2018年统计年鉴[20],在生活污水处理量达5 000万t以上的区县(江北区、南岸区和巴南区等),以及城镇居民达100万人以上的区县(江津区、合川区和涪陵区等)中筛选人口密集、生活垃圾或生活污水处理量大的集中式污水和垃圾处理设施。在筛选工业污水处理厂时,优先考虑了工业企业分布密集和工业污水排放量大的大型工业园区污水处理厂。最终选择了19个采样位点(图1),其中垃圾处理厂的W1是垃圾焚烧厂,W2和W3为垃圾填埋场,W1的渗滤液样品为垃圾焚烧前的渗沥液。于2019年7月采集这些企业污水处理设施的进水和出水样品,其中生活污水(domestic sewage,DS)和工业污水(industrial sewage,IS)经全规模污水处理厂处理,每个点位分别采集处理前废水500 mL和处理后废水1 000 mL各一份,垃圾处理厂的垃圾渗滤液经企业污水处理站处理,所有出水直接排入附近水环境中,每个点位分别采集处理前渗滤液50 mL和处理后废水1 000 mL各一份。水样用棕色玻璃瓶盛装,样品的长距离运输过程中均低温保存,在24 h内进行处理。各位点信息如表2所示,垃圾处理厂的渗滤液处理均采用了反渗透(reverse osmosis,RO)膜处理技术,污水处理厂普遍采用氧化沟(oxidation ditch,OD)、活性污泥法(activated sludge,AS)及厌氧-缺氧-好氧(anaerobic anoxic oxic,A2/O)的生物脱氮除磷工艺。

表2 本研究中垃圾处理厂(WTPs)和污水处理厂(STPs)的基本信息
Table 2 Information of waste treatment plants (WTPs) and sewage treatment plants (STPs) surveyed in this study

位点类型Sites type所在区县Locations位点编号Sites code渗滤液/污水年处理量Annual treatment capacity of leachate/sewage渗滤液/污水处理工艺Leachate/sewage treatment process废水排入河流Waste water disposal垃圾处理厂Waste incineration plant江津区 Jiangjin DistrictW138 218 m3RO长江 Yangtze River合川区 Hechuan DistrictW239 146 m3RO涪江 Fu River巴南区 Banan DistrictW366 000 m3RO长江 Yangtze River生活污水处理厂Domestic sewage treatment plant江津区 Jiangjing DistrictD14 000 ktOD长江 Yangtze River巴南区 Banan DistrictD230 290 ktAS长江 Yangtze River南岸区 Nanan DistrictD3311 960 ktA2/O长江 Yangtze River江北区 Jiangbei DistrictD4166 830 ktA2/O长江 Yangtze River涪陵区 Fuling DistrictD5620 ktA2/O长江 Yangtze River工业污水处理厂Industrial sewage treatment plant永川区 Yongchuan DistrictI16 400 ktAS永川河 Yongchuan River九龙坡区 Jiulongpo DistrictI21 030 ktA2/O长江 Yangtze River大渡口区 Dadukou DistrictI3340 ktAS长江 Yangtze River大渡口区 Dadukou DistrictI4350 ktAS长江 Yangtze River长寿区 Changshou DistrictI57 070 ktOD长江 Yangtze River涪陵区 Fuling DistrictI6180 ktOD长江 Yangtze River混合污水处理厂Mixed sewage treatment plant江津区Jiangjin DistrictM1生活(DS):660 ktDomestic sewage (DS): 660 kt工业(IS):8 280 kt Industrial sewage (IS): 8 280 ktAS长江Yangtze River江北区Jiangbei DistrictM2生活(DS):13 ktDomestic sewage (DS): 13 kt工业(IS):690 ktIndustrial sewage (IS): 690 ktAS长江Yangtze River两江新区Liangjiang DistrictM3生活(DS):920 ktDomestic sewage (DS): 920 kt工业(IS):8 280 ktIndustrial sewage (IS): 8 280 ktA2/O嘉陵江Jialing River渝北区Yubei DistrictM4生活(DS):14 520 ktDomestic sewage (DS): 14 520 kt工业(IS):6 220 ktIndustrial sewage (IS): 6 220 ktA2/O嘉陵江Jialing River涪陵区Fuling DistrictM5生活(DS):3 000 ktDomestic sewage (DS): 3 000 kt工业(IS):3 610 ktIndustrial sewage (IS): 3 610 ktOD长江Yangtze River

注:RO表示反渗透;OD表示氧化沟;AS表示活性污泥法;A2/O表示厌氧-缺氧-好氧。
Note:RO stands for reverse osmosis;OD stands for oxidation ditch;AS stands for activated sludge;A2/O stands for anaerobic-anoxic-oxic.

图1 采样位点分布图
Fig. 1 Location map of sampling sites in Chongqing City

1.3 样品前处理

水样经玻璃纤维滤膜过滤后备用。滤膜剪碎后置于50 mL特氟龙管中,加入10 mL的V(甲醇)∶V(二氯甲烷)=1∶1萃取液后超声20 min,取上清液至鸡心瓶中,重复2次,混合的上清液经旋转蒸发至1 mL后加入纯水50 mL混匀,和水样一起采用HLB固相萃取小柱萃取和净化。HLB小柱预先分别用10 mL甲醇、10 mL二氯甲烷和10 mL超纯水活化处理,控制样品以5 mL·min-1的流速经过萃取小柱,整个过程始终保持液面高于小柱填料上端,用10 mL纯净水冲洗HLB柱,真空干燥30 min后,用2 mL甲醇洗脱HLB小柱3次,再用2 mL二氯甲烷洗脱3次,洗脱液接至具塞玻璃离心管,用缓慢的氮气吹至近干,样品重新溶解于1 mL丙酮中,过0.22 μm滤膜后贮存于棕色进样瓶中,-20 ℃保存。样品中PEEs分析采用衍生化的方式增强其在仪器中的响应值[21],具体步骤为样品在上机前取100 μL样品氮吹至近干,加入100 μL BSTFA-TMCS于60 ℃水浴中反应60 min后进行。

1.4 仪器分析

使用Agilent 7890气相色谱仪和Agilent 5975C质谱仪,HP-5MS毛细管柱(30 m×0.25 mm×0.25 μm),内标法和多点校正曲线对目标化合物进行定量分析。以氦气为载气,流速1 mL·min-1,进样口温度260 ℃,传输线温度为150 ℃,离子源温度为230 ℃。选择离子扫描(SIM)模式,不分流进样,进样量为1 μL。其中测定PAEs的升温程序为:起始温度70 ℃,以15 ℃·min-1升至300 ℃,保持2 min。测定PEEs的升温程序为:起始温度70 ℃,保持1 min,以25 ℃·min-1升至190 ℃,以15 ℃·min-1升至300 ℃,保持4 min。

1.5 质量控制与质量保证

为保证实验数据的可靠性和准确性,采用内标法对本研究的目标化合物(表1)进行测定,标准曲线范围为5~1 000 μg· L-1,其线性相关系数(r2)>0.99。实验过程设置了流程空白样、溶剂空白样、样品平行样和基质加标样进行质量控制,平行样品相对标准偏差(relative standard deviation,RSD)<20%。方法检出限(method detection limit,MDL)定义为空白样品中目标化合物的均值加上3倍标准偏差;当目标物在空白样品中没有检出时,则以10倍信噪比计算。PEEs的基质加标回收率为70%~110%,方法检测限为0.21~0.34 ng·L-1,PAEs的基质加标回收率为78%~123%,方法检测限为0.12~0.68 μg·L-1

1.6 生态风险评估

参考欧盟化学物质风险评价技术指导文件(technical guidance document,TGD),对污染物生态风险的表征采用风险商(risk quotient,RQ)法,其计算为污染物的实测环境浓度(the measured environmental concentration,MEC)与表征该物质危害程度的预测无效应浓度(predicted no effect concentration,PNEC)之间的比值,即RQ=MEC/PNEC[22]。RQ>1表示该污染物对水环境中的生物存在潜在风险,其值越大潜在风险越高;RQ<1表明污染物的生态风险相对较低。

1.7 雌激素活性评估

采用各物质的雌二醇当量(estradiol equivalent quantity,EEQ)作为雌激素活性效应表征各物质对水生生物的内分泌干扰作用,计算方法为EEQ=EEF/MEC。式中:EEQ为各物质的雌二醇当量;MEC为各物质的环境暴露浓度测定值(ng·L-1);EEF为各物质的雌二醇当量因子(estradiol equivalent factor,ng·L-1)。

TGD将引起雌激素内分泌干扰效应的EEQ标准定为1 ng·L-1,即水环境中EEQ>1 ng·L-1的物质即被认为可能通过破坏生物体的正常激素功能,对河流中的鱼类等水生生物产生影响[23]。也有研究根据RQ值评估各位点出水的潜在雌激素风险,即各位点的EEQ值与雌二醇(estradiol,E2)的PNEC值的比值[24],而E2在水中的PNEC值为1.0 ng·L-1

2 结果与讨论(Results and discussion)

2.1 污水/废水处理厂进/出水PEEs和PAEs浓度水平

表3概述了在污水样品中各种目标化合物的测量浓度。在进水样本中检测到所有PEEs和13种PAEs。BPA的检测浓度最高,为272.97 μg·L-1。在出水样本中检测到所有PEEs和11种PAEs化合物,4-NP的检测浓度最高,为6.47 μg·L-1。进/出水样品中4-t-OP、4-NP、BPA、邻苯二甲酸二甲酯(dimethyl phthalate,DMP)、邻苯二甲酸二乙酯(diethyl phthalate,DEP)、DiBP、DEHP和DnBP的检出率均>50%,表明这些污染物普遍存在于各类污水中。美国环境保护局(US EPA)优先控制的6种PAEs (DMP、DEP、邻苯二甲酸二丁酯(di-n-butyl phthalate,DnBP)、邻苯二甲酸丁苄酯(butyl benzyl phthalate,BBzP)、DEHP、邻苯二甲酸二正辛酯(di-n-octyl phthalate,DnOP))在污水样品中除了DnOP其他PAEs均有检出[25]

表3 污水处理厂和垃圾处理厂污水中PEEs和PAEs浓度值
Table 3 The concentrations of PEEs and PAEs in influent and effluent samples in STPs and WTPs

化合物Compounds进水Influent (n=19)出水Effluent (n=19)平均值/(μg·L-1)Mean/(μg·L-1)中位数/(μg·L-1)Median/(μg·L-1)范围/(μg·L-1)Range/(μg·L-1)检出率/%Detection rate/%平均值/(μg·L-1)Mean/(μg·L-1)中位数/(μg·L-1)Median/(μg·L-1)范围/(μg·L-1)Range/(μg·L-1)检出率/%Detection rate/%4-t-OP2.430.210.02~33.21000.010.01nd~0.0568.44-NP6.453.000.01~29.71001.280.48nd~6.4789.5BPA24.51.18nd~27384.20.630.18nd~4.5394.7∑3i=1PEEs33.49.070.04~278-1.931.120.05~8.96-DMP2.050.690.14~20.41000.500.280.12~2.76100DEP1.541.07nd~5.5494.70.250.230.12~0.50100DiBP4.010.86nd~45.894.70.750.670.37~1.30100DEHP2.600.27nd~24.794.70.280.240.08~0.63100DnBP1.401.11nd~3.9389.50.710.730.38~1.04100BBzP0.050.01nd~0.3752.60.09ndnd~1.7115.8DEEP0.12ndnd~0.8926.30.09ndnd~1.0510.5DMEP0.01ndnd~0.155.26---0DMPP0.02ndnd~0.1321.10.01ndnd~0.145.26DNP0.070.02nd~0.4152.60.01ndnd~0.2310.5DPhP0.003ndnd~0.065.260.004ndnd~0.685.26DPeP0.01ndnd~0.0926.3---0DBEP0.01ndnd~0.1910.50.01ndnd~0.165.26∑13i=1PAEs11.94.220.14~97.2-2.702.301.37~4.19-

注:nd表示未检出;-表示无数据。
Note:nd is not detected;- means not available.

我国《城镇污水处理厂污染物排放标准》(GB18918—2002)中DnBP和DnOP浓度限值均为0.1 mg·L-1,本研究出水样品浓度远远低于排放限值。进一步参考各国的水质标准,如我国《地表水环境质量标准》(GB 3838—2002)中规定了BPA、DEP、DnBP和DEHP的限值分别为10、300、3和8 μg·L-1,加拿大地表水水质标准中也规定了DnBP和DEHP的最高限值为19 μg·L-1和16 μg·L-1[26],英国地表水环境质量标准规定了4-NP、DMP和DEHP的最高限值为2、20和1.3 μg·L-1[27],美国的水质基准中4-NP的规定限值为28 μg·L-1[28]。本研究出水样品的检出浓度除了4-NP超出了英国地表水环境质量标准,其他均无超标,考虑到污水排入水环境中的稀释作用,本研究出水样品的检出浓度均低于标准限值。Gao等[29]总结了近10年以来国内外污水处理厂中PAEs的浓度水平,发现中国各地的污水处理厂污水中PAEs的含量没有显著差异,而且与欧洲、美国、加拿大和澳大利亚等地区的研究结果相似,其报告值一般低于100 μg·L-1,除了芬兰和荷兰,其污水中PAEs的含量超过100 μg·L-1

图2显示了4种污染源进出水中PEEs和PAEs的浓度变化,流域的浓度数据来自笔者课题组于2018年7月采集的重庆市长江流域地表水样品,其中长江段采自入境断面朱沱至国控断面苏家共8个采样点,嘉陵江段采自入境断面金子至国控断面大溪沟共4个采样点[17-21],为本研究中污水/废水处理厂排水的受纳水体。由图2可知,对于污染源进水,垃圾渗滤液中PEEs和PAEs的总浓度最高(分别为11.07~278.41 μg·L-1和25.83~97.17 μg·L-1),其次为涉生活污水处理的点位进水,工业污水处理厂的进水最低(分别为0.04~13.97 μg·L-1和0.14~4.69 μg·L-1)。DEHP是生活垃圾中最常见的PAEs类污染物,而DnBP和DEP是个人护理产品中最常用的PAEs类污染物[30],结合本研究结果推测,生活源是PEEs和PAEs的重要污染来源之一。

图2 垃圾处理厂、污水处理厂和流域样品中PEEs和PAEs的总浓度水平
注:WTPs表示垃圾处理厂;DSTPs表示生活污水处理厂;ISTPs表示工业污水处理厂;MSTPs表示混合污水处理厂。
Fig.2 Total concentration of PEEs and PAEs in the WTPs,STPs and river samples
Note:WTPs stands for waste treatment plants;DSTPs stands for domestic sewage treatment plants;ISTPs stands for industrial sewage treatment plants;MSTPs stands for mixed sewage treatment plants.

对于污染源出水,4种污染源出水中PEEs和PAEs的浓度相当,与流域地表水的检出浓度相比,污染源的PEEs总浓度(分别为0.05~8.96 μg·L-1)稍高于流域地表水(长江段和嘉陵江段分别为0.05~4.70 μg·L-1和0.18~2.15 μg·L-1)。流域地表水的PAEs总浓度(长江段和嘉陵江段分别为10.29~81.83 μg·L-1和6.18~17.84 μg·L-1)则是显著高于污染源(平均值为1.37~4.19 μg·L-1)。课题组前期研究结果显示,重庆市流域水体中PAEs的浓度与黄河中下游水体和长江武汉段等水体的结果相当,在重庆市入境断面朱沱和金子PAEs的浓度分别为10.29 μg·L-1和17.52 μg·L-1,可见流域水体中PAEs的本底值较高[17]。PAEs具有较高的疏水性,其随着生产使用释放进入水体后倾向于被水中的悬浮有机质吸附,进而在沉积物中富集[31]。因此,即使污染源中PAEs浓度较低,但随着污水的持续性排放,PAEs在沉积物长期储存,也会导致其再次悬浮释放。

对进水中检出率>50%的EDCs化合物进行Spearman相关性分析(表4),进水中4-NP、4-t-OP和DEP之间的含量分别存在显著的相关性,DiBP除了与BPA、DnBP之间的含量显著相关以外,同时与4-t-OP、DMP、DEP和DEHP的含量也显著相关。结果显示,不同的PEEs和PAEs之间的含量显著相关,表明污水中这些EDCs的来源高度相关。对不同类型来源的进水中检出率>50%的EDCs化合物进行差异性分析,只有DEP和DnBP这2种污染物浓度具有显著性差异,即垃圾渗滤液中DEP浓度显著高于工业污水(P<0.01),DBP浓度显著高于工业污水(P<0.01)和混合污水(P<0.05),生活污水中DEP浓度显著高于工业污水(P<0.05)。Qi等[32]对1996年以来我国垃圾渗滤液中常见污染物的研究进行了综述,发现垃圾渗滤液中污染物浓度一般比污水处理厂的进水高出几个数量级,且不同垃圾渗滤液中污染物浓度范围差异很大,如BPA含量可从低于检测限到高达4 500 mg·L-1,与本研究结果相符。

表4 进水中不同内分泌干扰物(EDCs)(检出率>50%)之间的相关性
Table 4 Spearman’s correlation data between endocrine disrupting compounds (EDCs) (detection rate>50%) in influent samples

4-t-OP4-NPBPADMPDEPDiBPDEHPDnBPBBzP4-t-OPr1P4-NPr0.768**1P0.000BPAr0.3940.3991P0.0950.091DMPr0.3040.2840.3731P0.2070.2380.116DEPr0.472*0.504*0.3810.465*1P0.0410.0280.1070.045DiBPr0.463*0.4440.647**0.644**0.711**1P0.0460.0570.0030.0030.001DEHPr0.2740.1790.3340.623**0.675**0.691**1P0.2570.4640.1620.0040.0020.001DnBPr0.1750.1510.536*0.4370.4050.613**0.3861P0.4750.5370.0180.0610.0850.0050.102BBzPr-0.364-0.464*-0.1210.0450.0560.0200.2970.0531P0.1260.0460.6220.8560.8210.9340.2170.830

注:*显著性水平为0.05,**显著性水平为0.01。
Note:*correlation is significant at the 0.05 level;**correlation is significant at the 0.01 level.

2.2 污水/废水处理厂进/出水PEEs和PAEs组成特征变化

由图2可知,各类污染源的处理设施对PEEs和PAEs均有一定的去除效果,其中4-t-OP和DNP的平均去除率达到88%和95%。本研究进一步探究了不同污水处理工艺对PEEs和PAEs的去除效果,如图3所示,垃圾渗滤液的处理均采用了膜分离技术,除了对DnBP的平均去除率为69%以外,对其余PEEs和PAEs的平均去除率均达到80%以上,是去除效果最好的一种污水处理工艺。A2/O法对DEHP和DMP的平均去除率较低,分别为3.8%和25.4%,活性污泥和氧化沟技术对PEEs和PAEs的去除最低,除了BBzP和DNP,其他污染物均出现出水浓度高于进水浓度的情况。PAEs可以在不同条件下被微生物降解[33],但是长链PAEs的生物降解是一个耗时很长的过程[34],因此以生物降解方式对PAEs类污染物的去除效率可能较其他污水处理工艺低,Wu等[35]研究指出,偶尔的负去除值可能是由于PAEs的前体进一步降解引起的。针对负去除率的现象,还需进一步分析污水处理全过程及各种污染物载体中目标物的含量。以往研究表明,由于传统污水处理装置并没有专门设计去除这些ECDs,其去除率较低[36],如传统活性污泥法不能去除大部分有毒有机污染物[37-38]。而目前污水处理装置采用了先进的处理技术,如膜生物反应器(membrane bio-reactor,MBR)[39]、活性炭吸附[40]或其他新型吸附剂[41]技术等,可以去除污水中的大部分有机污染物,与本研究结果相符。

污染物在污水处理过程中的生物降解受到污泥的解吸和微生物活动的影响,最终的浓度取决于这2个过程之间的平衡[42-43]。PAEs的去除率较低可能原因是它们疏水性相对较高,在污泥上的吸附趋势相对较高而减少了生物降解的作用。BBzP和DNP去除率较其余PAEs高,可能是其相对图3中其余5种PAEs的检出率较低,检出浓度低1~2个数量级,更容易去除。大多数雌激素复合物在污水处理前或处理过程中会通过微生物过程裂解为游离单体[10],如未处理污水的或处理过程中的4-NP可能是其前体壬基酚聚氧乙烯醚(nonylphenol polyethylene glycol ether,NPEOs)通过微生物分解产生的[44]

图3 不同污水处理工艺对PEEs和PAEs的去除效果
Fig. 3 Removal efficiencies of various treatment processes for PEEs and PAEs

2.3 生态风险水平和雌激素活性效应评估

对出水中检出率>50%的8种EDCs化合物,通过RQ值和EEQ值分别评估了4种污染源出水的潜在生态风险水平和雌激素活性效应。如图4所示,出水中生态风险和雌激素活性最高的化合物均为4-NP,垃圾处理厂W1、生活污水处理厂D1和D4以及工业污水处理厂I3的出水中4-NP的RQ值和EEQ值均超过1.0,表明这些位点出水中的4-NP对水环境中的生物存在潜在风险,可能会破坏生物体的正常激素功能。DMP和DEP在4种污染源出水中的RQ值和EEQ值较低,表明其对水环境中生物的影响较小。然而废水排入流域后发生的稀释效应将会导致污染物浓度的减少,本研究只能推测这些污水中的污染物的浓度是否足够高,从而对这些污水受纳河流中的水生生物产生影响,若评估污水释放到水环境中所造成的实际风险,需进一步研究这些污染物稀释后浓度是否会对水生生物造成危险。根据目前的研究结果,4-NP是各种污染源出水中生态风险商和雌激素活性的主要贡献污染物,其可作为污染源排放监测的关键EDCs类污染物,用于污染物排放治理和潜在风险预测。

图4 各采样位点出水中PEEs和PAEs的生态风险商值(RQ)和雌激素活性水平(EEQ)
注:WTPs表示垃圾处理厂;DSTPs表示生活污水处理厂;ISTPs表示工业污水处理厂;MSTPs表示混合污水处理厂。
Fig.4 Risk quotient (RQ) and estradiol equivalents (EEQ) contributed by PEEs and PAEs in effluent of different sample sites
Note:WTPs stands for waste treatment plants;DSTPs stands for domestic sewage treatment plants;ISTPs stands for industrial sewage treatment plants;MSTPs stands for mixed sewage treatment plants.

综上所述,本研究表明:

(1) 在垃圾处理厂和各类污水处理厂的进出水中共检测到3种PEEs和13种PAEs,其中垃圾渗滤液中PEEs和PAEs的总浓度最高,分别为11.07~278.41 μg·L-1和25.83~97.17 μg·L-1,工业污水处理厂的进水最低,分别为0.04~13.97 μg·L-1和0.14~4.69 μg·L-1,各类排放源的出水中PEEs和PAEs的浓度相当,分别为0.05~8.96 μg·L-1和1.37~4.19 μg·L-1,与国内其他地区的研究结果相当。

(2) 进水中不同的PEEs和PAEs之间的含量显著相关,表明污水中这些EDCs的来源高度相关。各污染源对4-t-OP和DNP的平均去除率达到88%和95%,膜分离技术去除效果最好,活性污泥和氧化沟技术去除率较低。

(3) 4-NP是各种污染源出水中生态风险商和雌激素活性的主要贡献污染物,表明其对水环境中的生物存在一定的潜在风险。

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Emission Characteristics of Typical Environmental Estrogens from Waste Treatment Plants and Sewage Treatment Plants in Chongqing

Shi Yungang1,Liu Jialie1,Tang Na1,Ma Yan2,Zhuang Xi2,*,Li Jie1,Zheng Jing2

1.Chongqing Solid Waste Management Center,Chongqing 400020,China

2.State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment,South China Institute of Environmental Sciences,Ministry of Ecology and Environment,Guangzhou 510655,China

Abstract:To investigate the emission characteristics of phenolic environmental estrogens (PEEs) and phthalic acid esters (PAEs) from sewage treatment plants (STPs) and waste treatment plants (WTPs) in Chongqing,and to assess their potential risks to the Yangtze River Basin,the concentrations of 3 PEEs and 16 PAEs in influent and effluent of 3 WTPs and 16 STPs in Chongqing were analyzed,and the ecological risk levels and estrogenic effects in effluent were assessed as well.3 PEEs and 11 PAEs were detected in the influent and effluent.Highest concentrations of PEEs and PAEs were detected in landfill leachate,with total concentrations ranging from 11.07~278.41 μg·L-1 and 25.83~97.17 μg·L-1,respectively;while the lowest was detected in influent of industrial sewage treatment plants,with total concentrations ranging from 0.04~13.97 μg·L-1 and 0.14~4.69 μg·L-1,respectively.Similar concentrations for PEEs and PAEs were found in the effluent,ranging from 0.05~8.96 μg·L-1 and 1.37~4.19 μg·L-1,respectively.The average removal rates of 4-tert-octylphenol (4-t-OP) and dinonyl phthalate (DNP) were up to 88% and 95%,respectively.Membrane separation technology were more effective in removing estrogens from waste,while activated sludge and oxidation ditch had lower removal efficiency.Nonylphenol (4-NP) showed the highest ecological risk and estrogenic activity in the effluents,indicating a potential risk to organisms in aquatic environment.

Keywords:phenolic environmental estrogens;phthalic acid esters;sewage treatment plants;waste treatment plants;emission characteristics

收稿日期2021-03-22

录用日期:2021-05-16

文章编号:1673-5897(2022)3-189-12

中图分类号:X171.5

文献标识码:A

Received 22 March 2021

accepted 16 May 2021

基金项目重庆市长江流域化学品环境风险管理技术支撑体系研究(2019-112)

第一作者石运刚(1978—),男,学士,研究方向为化学品风险防控,E-mail:sygonline@sina.com

*通讯作者(Corresponding author),E-mail:zhuangxi@scies.org

DOI:10.7524/AJE.1673-5897.20210322001

石运刚,刘嘉烈,唐娜,等.重庆市垃圾处理厂和污水处理厂中典型环境内分泌干扰物的排放特征[J].生态毒理学报,2022,17(3):189-200

Shi Y G,Liu J L,Tang N,et al.Emission characteristics of typical environmental estrogens from waste treatment plants and sewage treatment plants in Chongqing [J].Asian Journal of Ecotoxicology,2022,17(3):189-200 (in Chinese)

通讯作者简介:庄僖(1988—),男,学士,工程师,主要研究方向为环境科学。