-
印染纺织行业排放的废水是我国排放量最大的工业废水之一,其组分复杂且水质变化大,含有大量的染料、表面活性剂及其他难降解的有机污染物[1]。废水中近85%的有机污染物经过各种处理工艺后被去除,但排水中仍含有各种降解及代谢产物和难降解污染物,虽然含量低但仍具有致癌、致畸和致突变作用,这对天然接收水体造成了严重的不利影响[2]。其中溶解性有机物(dissolved organic matter, DOM) 作为印染外排废水中污染物最主要的存在形式,其具体成分及含量会直接影响到出水水质,由于DOM不易被完全降解及矿化,常规的有机物指标如化学需氧量,总有机碳等只能反映印染外排废水中有机物的总量,不能反映DOM具体组分构成及含量,难以掌握其对接收水体的环境危害。
三维荧光光谱(excitation-emission maps, EEMs)作为一种可定性定量研究 DOM 的光谱指纹分析技术,可方便快捷地揭示DOM所含的类蛋白(类色氨酸,类酪氨酸等)和类腐殖质(类胡敏酸,类富里酸等)荧光团的组成信息[3]。常用荧光指数(fluorescence index, FI),腐殖化指数(humification index, HIX),自生源指数(biological index, BIX)来分别判断DOM腐殖质的来源[4],估计DOM的腐殖化程度及衡量水体中生物活动对DOM的贡献[5]。EEM光谱通常是由若干相互叠加的荧光团组成,导致部分峰无法识别或者指认不准确。Stedmon[6]率先提出利用三维荧光结合平行因子分析(PARAFAC)技术将DOM三维荧光光谱分为单个荧光团或一组具有独特激发和发射光谱的相似荧光团。但平行因子只能得到单独荧光组分及该组分对应的最大荧光强度,而无法定量分析该荧光组分区域的总荧光强度。荧光区域积分(fluorescence regional integration,FRI)[7]作为另一种荧光光谱解析方法,可对具体区域的荧光强度定量表征,在一定程度上克服了以上不足。通过PARAFAC及FRI的方法,可以准确识别出EEM中荧光峰的个数,位置和具体区域荧光强度等相关信息。
目前的研究主要集中于天然陆地水环境DOM和受污染水体DOM等[4-6, 8-9],有关印染外排废水DOM的光学特性研究还不多见。本研究结合三维荧光光谱和平行因子分析,辅以荧光区域积分法,分析对比经过不同处理工艺后的印染外排废水DOM的荧光特征,丰富关于印染外排废水中DOM的调查资料,为其特征研究提供依据,为优化印染废水处理厂的运行和监控管理提供技术参考。
印染外排废水中溶解性有机质的荧光特性
Fluorescence characteristics of dissolved organic matter in textile-dyeing effluents
-
摘要: 通过三维荧光(EEM)光谱技术,结合平行因子分析(PARAFAC)及荧光区域积分法(FRI),对我国珠三角的五家印染废水处理厂外排废水的溶解性有机质(DOM)进行定性及定量表征。五组水样DOM的EEM光谱中类蛋白荧光峰最为明显,结合荧光指数(FI),自生源指标(BIX)及腐殖化指标(HIX),发现DOM的腐殖质主要来源于微生物的活动。基于PARAFAC的结果发现印染外排废水DOM的构成组分可分为类蛋白荧光组分C1(Em/Ex=320/275 nm)和C2(Em/Ex=350/225,275 nm),及类腐殖质荧光组分C3(Em/Ex=460/250,300 nm)。不同组分之间的显著相关性表明他们具有同源或同结构相似性,其中C2与C3之间相关性最高(r=0.7949),其次是C1与C2(r=0.7936),而C1与C3之间相关性不显著(P>0.05)。结合FRI,发现外排废水中DOM的有机物构成以溶解性微生物代谢产物和芳香性蛋白类为主,类腐殖质的含量相对较低。三维荧光光谱结合平行因子分析和荧光区域积分法,能有效监测及分析外排废水中低浓度有机物的具体信息,可以作为一种有效的水质监测手段。Abstract: Based on parallel factor analysis (PARAFAC) and fluorescence regional integration (FRI), excitation emission matrix (EEM) spectroscopy was used to qualitatively and quantitatively characterize dissolved organic matter (DOM) in textile-dyeing effluents. The protein-like fluorescence peaks in the EEM spectroscopy of DOM were more obvious. Combining the fluorescence index (FI), biological index (BIX) and the humification index (HIX), it was found that the source of DOM was mainly microbial activity. Based on the results of PARAFAC, it was found that DOM can be divided into protein-like components C1 (Em/Ex=320/275 nm) and C2 (Em/Ex=350/225, 275 nm), and humic-like fluorescent component C3 (Em/Ex=460/250, 300 nm). Significant correlations between different components indicated that they were homologous or homostructured. The correlation between C2 and C3 was the highest (r=0.7949), followed by C1 and C2 (r=0.7936), while the correlation between C1 and C3 was not significant (P>0.05). Combined with FRI, it was found that the organic matter composition of DOM was mainly composed of soluble microbial metabolites and aromatic proteins, the content of humic substances was relatively low. The EEM spectrum combined with PARAFAC and FRI could effectively monitor and analyze the specific information of low-concentration organic matter in the effluents. It could be used as an effective technical means for water quality monitoring of the treatment plant.
-
表 1 印染外排废水DOM的基本光学性质
Table 1. Several fluorescence parameters of DOM from TDE
荧光强度(QSU) FI BIX HIX TDP1 8.890 1.562 0.963 0.680 TDP2 39.068 2.251 0.741 3.205 TDP3 22.600 1.987 0.894 0.618 TDP4 44.294 2.190 1.243 1.061 TDP5 53.407 2.318 0.709 4.033 表 2 印染外排废水DOM荧光组分特征
Table 2. Fluorescence components of DOM from TDE
表 3 印染外排废水DOM的荧光区域积分标准体积(Φi,n,×105 au·nm2)
Table 3. Regional fluorescence volume integral of DOM
Region Ⅰ Region Ⅱ Region Ⅲ Region Ⅳ Region Ⅴ Region Ⅵ Φi,n TDP1 3.957 7.595 8.155 7.811 4.375 2.130 34.023 TDP2 13.216 26.248 61.307 50.916 47.392 14.335 213.413 TDP3 11.015 32.619 27.542 24.860 14.970 4.407 115.412 TDP4 13.123 25.081 59.148 49.386 46.493 14.062 207.293 TDP5 17.440 49.196 86.070 80.351 90.052 31.745 354.854 -
[1] LIANG J, NING X A, KONG M, et al. Elimination and ecotoxicity evaluation of phthalic acid esters from textile-dyeing wastewater [J]. Environ Pollut, 2017, 231(Pt 1): 115-122. [2] ASGHAR A, RAMAN A A A, DAUD W M A W. Advanced oxidation processes for in-situ production of hydrogen peroxide/hydroxyl radical for textile wastewater treatment: A review [J]. Journal of Cleaner Production, 2015, 87: 826-838. doi: 10.1016/j.jclepro.2014.09.010 [3] LI W T, CAO M J, YOUNG T, et al. Application of UV absorbance and fluorescence indicators to assess the formation of biodegradable dissolved organic carbon and bromate during ozonation [J]. Water Research, 2017, 111: 154-162. doi: 10.1016/j.watres.2017.01.009 [4] BIRDWELL J E, ENGEL A S. Characterization of dissolved organic matter in cave and spring waters using UV–Vis absorbance and fluorescence spectroscopy [J]. Organic Geochemistry, 2010, 41(3): 270-280. [5] HUGUET A, VACHER L, SAUBUSSE S, et al. New insights into the size distribution of fluorescent dissolved organic matter in estuarine waters [J]. Organic Geochemistry, 2010, 41(6): 595-610. doi: 10.1016/j.orggeochem.2010.02.006 [6] STEDMON C A, MARKAGER S J L, OCEANOGRAPHY. Resolving the variability in dissolved organic matter fluorescence in a temperate estuary and its catchment using PARAFAC analysis[J]. Limnology & Oceanography, 2005,50(2): 686-697. [7] HE X S, XI B D, WEI Z M, et al. Fluorescence excitation-emission matrix spectroscopy with regional integration analysis for characterizing composition and transformation of dissolved organic matter in landfill leachates [J]. J Hazard Mater, 2011, 190(1-3): 293-299. doi: 10.1016/j.jhazmat.2011.03.047 [8] 李秋材, 张莉, 王圣瑞, 等. 光照对湖泊上覆水DON影响机制及环境学意义 [J]. 环境化学, 2017, 36(3): 521-531. LI Q C, ZHANG Li, WANG S R, et al. Influence of light on DON characteristics in overlying water and its environmental implication [J]. Environmental Chemistry, 2017, 36(3): 521-531(in Chinese).
[9] 肖隆庚, 陈文松, 陈国丰, 等. 中国南海CDOM三维荧光光谱特征研究 [J]. 环境科学学报, 2014, 34(1): 160-167. XIAO L G, CHEN W S, CHEN G F, et al. Fluorescence excitation-emission matrix spectroscopy of chromophoric dissolved organic matter in the South China Sea [J]. Acta Scientiae Circumstantiae, 2014, 34(1): 160-167(in Chinese).
[10] LEE M H, OSBURN C L, SHIN K H, et al. New insight into the applicability of spectroscopic indices for dissolved organic matter (DOM) source discrimination in aquatic systems affected by biogeochemical processes [J]. Water Research, 2018, 147: 164-176. doi: 10.1016/j.watres.2018.09.048 [11] CHEN W, WESTERHOFF P, LEENHEER J A, et al. Fluorescence excitation-emission matrix regional integration to quantify spectra for dissolved organic matter [J]. Environ Sci Technol, 2003, 37(24): 5701-5710. [12] 隋志男, 郅二铨, 姚杰, 等. 三维荧光光谱区域积分法解析辽河七星湿地水体DOM组成及来源 [J]. 环境工程技术学报, 2015, 5(02): 114-120. SUI Z N, ZHI E Q, YAO J, et al. Characterization of DOM composition and origin using three-dimensional fluorescence spectroscopy coupled with region integration method in Qixing Wetland [J]. Journal of Environmental Engineering Technology, 2015, 5(02): 114-120(in Chinese).
[13] 何伟, 白泽琳, 李一龙, 等. 溶解性有机质特性分析与来源解析的研究进展 [J]. 环境科学学报, 2016, 36(2): 359-372. HE W, BAI Z L, LI Y L, et al. Advances in the characteristics analysis and source identification of the dissolved organic matter [J]. Acta Scientiae Circumstantiae, 2016, 36(2): 359-372(in Chinese).
[14] MCKNIGHT D M, BOYER E W, WESTERHOFF P K, et al. Spectrofluorometric characterization of dissolved organic matter for indication of precursor organic material and aromaticity [J]. Limnol Oceanogr, 2001, 46(1): 38-48. [15] HUGUET A, VACHER L, RELEXANS S, et al. Properties of fluorescent dissolved organic matter in the Gironde Estuary [J]. Organic Geochemistry, 2009, 40(6): 706-719. doi: 10.1016/j.orggeochem.2009.03.002 [16] ZHANG Y, ZHANG E, YIN Y, et al. Characteristics and sources of chromophoric dissolved organic matter in lakes of the Yungui Plateau, China, differing in trophic state and altitude [J]. Limnol Oceanogr, 2010, 55(6): 2645-2659. [17] HUR J, LEE T H, LEE B M. Estimating the removal efficiency of refractory dissolved organic matter in wastewater treatment plants using a fluorescence technique [J]. Environ Technol, 2011, 33(15/16): 1843-1850. [18] LI W T, XU Z X, LI A M, et al. HPLC/HPSEC-FLD with multi-excitation/emission scan for EEM interpretation and dissolved organic matter analysis [J]. Water Research, 2013, 47(3): 1246-1256. [19] ISHII S K, BOYER T H. Behavior of reoccurring PARAFAC components in fluorescent dissolved organic matter in natural and engineered systems: a critical review [J]. Environ Sci Technol, 2012, 46(4): 2006-2017. [20] MURPHY K R, HAMBLY A, SINGH S, et al. Organic matter fluorescence in municipal water recycling schemes: toward a unified PARAFAC model [J]. Environ Sci Technol, 2011, 45(7): 2909-2916. doi: 10.1021/es103015e [21] 贺润升, 徐荣华, 韦朝海. 焦化废水生物出水溶解性有机物特性光谱表征 [J]. 环境化学, 2015, 34(1): 129-136. HE R S, XU R H, WEI C H, et al. Spectral characterization of dissolved organic matter in bio-treated effluent of coking wastewater [J]. Environmental Chemistry, 2015, 34(1): 129-136(in Chinese).
[22] 姚璐璐, 涂响, 于会彬, 等. 三维荧光区域积分评估城市污水中溶解性有机物去除 [J]. 环境工程学报, 2013, 7(2): 411-416. YAO L L, Tu X, YU H B, et al. Evaluation of dissolved organic matter removal in municipal wastewater based on fluorescence regional integration [J]. Chinese Journal of Environmental Engineering, 2013, 7(2): 411-416(in Chinese).
[23] 韩宇超, 郭卫东. 九龙江河口有色溶解有机物的三维荧光光谱特征 [J]. 环境科学学报, 2009, 29(3): 641-647. doi: 10.3321/j.issn:0253-2468.2009.03.027 HAN Y C, GUO W D. The fluorescence excitation emission matrix spectroscopy of chromophoric dissolved organic matter in the Jiulong River Estuary [J]. Acta Scientiae Circumstantiae, 2009, 29(3): 641-647(in Chinese). doi: 10.3321/j.issn:0253-2468.2009.03.027
[24] 郑璐, 许光明, 陈俊, 等. 污水厂深度处理过程中有机物三维荧光光谱的平行因子分析研究 [J]. 环境科学与管理, 2015, 40(10): 89-91. doi: 10.3969/j.issn.1673-1212.2015.10.021 ZHENG L, XU G M, CHEN J, et al. Organic matter removal based on 3D fluorescence spectroscopy and parafac analysis during wastewater advanced treatment process [J]. Environmental Science and Management, 2015, 40(10): 89-91(in Chinese). doi: 10.3969/j.issn.1673-1212.2015.10.021
[25] 王士峰, 吴静, 程澄, 等. 某印染废水的水质指纹特征 [J]. 光谱学与光谱分析, 2015, 35(12): 3440-3443. WANG S F, WU J, CHENG C, et al. Aqueous fingerprint of printing and dyeing wastewater [J]. Spectroscopy and Spectral Analysis, 2015, 35(12): 3440-3443(in Chinese).
[26] 何磊, 王志伟, 吴志超. 餐饮废水MBR处理过程中DOM的三维荧光光谱分析 [J]. 中国环境科学, 2011, 31(2): 225-232. HE L, WANG Z W, WU Z C. Excitation-emission matrix fluorescence spectra analysis of dissolved organic matter in MBR used for restaurant wastewater treatment [J]. China Environmental Science, 2011, 31(2): 225-232(in Chinese).
[27] BAGHOTH S A, SHARMA S K, AMY G L. Tracking natural organic matter (NOM) in a drinking water treatment plant using fluorescence excitation–emission matrices and PARAFAC[J]. Water Research, 2011, 45(2): 800-809. [28] WANG Z P, ZHANG T. Characterization of soluble microbial products (SMP) under stressful conditions [J]. Water Research, 2010, 44(18): 5499-5509.