-
随着工农业的迅速发展,氯代烃类有机物作为生产原料和溶剂被人类广泛地应用在工业生产、农药、干洗和医疗等行业[1],造成了一系列环境问题。氯代烃类在环境中随着雨水、径流等渗滤到土壤中[2],被土壤吸附一部分后渗漏到地下含水层,导致地下水污染[3],其中地下水中四氯乙烯、三氯乙烯及四氯化碳等污染尤为普遍[4-6]。本研究中选取一种典型氯代烃PCE作为研究对象,该物质是在常温下易挥发、非易燃的重质非水溶相液体(dense non-aqueous phase liquids,DNAPLs),化学性质稳定,且有很强的生物毒性和潜在的生物累积性,并具有刺激性、致敏性、致突变性、致畸性、致癌性等特性,已被较多国家列为优先控制污染物[7]。一旦PCE通过各种途径进入地下环境,会下渗到地下水深层,严重污染地下水资源,对生态环境和人体健康产生极大的危害[8]。1999年北京市地下水有机污染调查结果表明,北京地区有2处氯代烃污染区域面积超过10 km2,主要污染物为TCE和PCE,最高浓度分别为487.6 μg∙L−1和63.74 μg∙L−1,其中PCE的检出率较高[9]。为了保护生态环境及促进可持续发展,地下水中氯代烃污染问题亟待解决,地下水水质保护和污染修复刻不容缓[10]。
考虑到微生物修复技术具有易于原位修复、处理成本低、无二次污染且可以实现无害化等优点,故进一步研究微生物群落对PCE的降解非常必要[11]。近年来,国内外研究人员对氯代烃的生物降解进行了大量探索和研究[12-19]。在厌氧条件下,氯代烯烃可以作为某些细菌的终端电子受体,通过厌氧微生物作用发生还原脱氯,生成次级产物,最终达到无害化的修复目的,而加入一些有机质进行共代谢可以提高其降解速率[12-14]。有研究[15]发现,将厌氧细菌Y51株和好氧性混合株P. pseudocalcaligenes KF707-D3株综合运用可以将难生物降解的PCE完全分解。实际上,单一的厌氧菌或好氧菌很难彻底快速降解PCE[16]。迄今为止,仅发现Dehalococcoides mccartyi属的菌株能使PCE完全脱氯[17],且该属菌株对碳源要求较高,一般需要醋酸盐作为碳源[18],生长条件较为苛刻。然而,多种常见微生物如脱硫单胞菌,硫磺菌等可以协同合作将PCE还原脱氯[19]。
目前,对微生物修复氯代烃的研究主要集中在单一好氧菌株以及厌氧菌株的运用。因此,有必要研究地下水环境中微生物群落降解氯代烃的特性,从而进一步探索提高氯代烃生物降解速率的可行方法。尽管有很多学者研究某类共代谢基质条件下微生物菌株是否能够成功脱氯,但很少有学者针对微生物群落在不同共代谢基质条件下的脱氯能力开展相关研究[20]。因此,根据现阶段氯代烃修复的研究经验,本研究选取一种典型氯代烃PCE,旨在评估模拟地下水环境下降解菌群的共代谢脱氯能力。本研究采用振荡培养法[21]来筛选并鉴定出PCE优势降解菌群,对环境因素开展实验并对其进行了条件优化,探索了不同共代谢基质条件下PCE降解的规律,建立了反应动力学模型,比较了不同共代谢基质条件下微生物的脱氯能力。
共代谢基质强化微生物修复四氯乙烯污染地下水
Co-substrates enhanced bioremediation of groundwater contaminated by tetrachloroethylene
-
摘要: 针对微生物修复地下水中四氯乙烯 (tetrachloroethylene,PCE) 周期长的问题,通过添加共代谢基质强化微生物修复技术以提高修复速率。以某污水处理厂的厌氧活性污泥为菌种来源,采用振荡培养法进行PCE高效降解菌群的驯化和筛选,对微生物降解PCE的温度、初始pH和PCE初始浓度3种影响因素进行了条件优化;使用甲醇、乙醇、葡萄糖、酵母浸膏以及乳酸钠作为共代谢基质,研究了不同共代谢基质条件下微生物群落对PCE的降解规律,并建立了反应动力学模型。结果表明:在种水平上,梭状芽孢杆菌Clostridium sp. FCB45是优势菌种;PCE初始浓度为1 mg∙L−1,pH在中性,温度为30 ℃,共代谢基质为酵母浸膏时,微生物群落的降解效果最好,PCE降解率可高达96.75%,降解速率常数最高可达0.327 d−1;添加共代谢基质强化的微生物降解过程全部符合一级反应动力学模型。添加共代谢基质的微生物实验结果表明,添加共代谢基质可以有效缩短微生物修复周期,对污染地下水的原位生物修复具有一定的参考价值。Abstract: Aiming at the long remediation timeframe associated with bioremediation of tetrachloroethylene (PCE)-contaminated groundwater, the addition of co-substrates has been explored to improve the biodegradation rate and reduce the remediation duration. In this study, an acclimated microbial consortium for PCE biodegradation was enriched by the shaking cultivation method with a microbial source from anaerobic sludge collected from a wastewater treatment plant. PCE degradation efficiency was determined and the impacts of different environmental factors such as temperature, initial pH and initial concentration of tetrachloroethylene were optimized. In addition, the enhanced biodegradation efficiencies of PCE using different co-substrates, including methanol, ethanol, glucose, yeast extract and sodium lactate, were investigated, and the corresponding biodegradation kinetic models were also developed. Experimental results showed that Clostridium sp. FCB45 played a significant role in PCE biodegradation. The best PCE biodegradation effect occurred with the efficiency up to 96.75% at PCE initial concentration of 1 mg∙L−1, neutral pH, 30 ℃, and co-substrate of yeast extract, and the highest biodegradation rate constant was 0.327 d−1. The enhanced biodegradation using different co-substrates can all be described by the first-order reaction kinetics. It was concluded that the addition of co-substrates can effectively shorten the remediation timeframe, which provides a theoretical and experimental basis for in situ enhanced bioremediation of PCE-contaminated groundwater.
-
Key words:
- tetrachloroethylene (PCE) /
- bioremediation /
- co-substrates /
- contaminated groundwater
-
表 1 不同共代谢基质对应的PCE的反应动力学模型方程及相关参数
Table 1. Reaction kinetics equations and parameters of PCE degradation using different co-substrates
共代谢基质 动力学模型 R2 反应速率常数k/d−1 半衰期t1/2/d 甲醇 $ c = 1.39{{\rm{e}}^{ - \frac{t}{{7.02}}}} - 0.682$ 0.972 0.142 1.665 乙醇 $ c = 4.38{{\rm{e}}^{ - \frac{t}{{27.23}}}} - 3.67$ 0.928 0.037 2.296 葡萄糖 $ c = 1.62{{\rm{e}}^{ - \frac{t}{{6.875}}}} - 0.792$ 0.963 0.145 2.095 酵母浸膏 $ c = 1.11{{\rm{e}}^{ - \frac{t}{{3.055}}}} - 0.223$ 0.988 0.327 1.571 乳酸钠 $ c = 1.895{{\rm{e}}^{ - \frac{t}{{8.906}}}} - 1.106$ 0.955 0.112 2.161 无共代谢基质 $ c = 1.746{{\rm{e}}^{ - \frac{t}{{10.155}}}} - 1.061$ 0.884 0.098 2.409 -
[1] VOGEL M, NIJENHUIS I, LLOYD J, et al. Combined chemical and microbiological degradation of tetrachloroethene during the application of carbo-iron at a contaminated field site[J]. Science of the Total Environment, 2018, 628-629: 1027-1036. doi: 10.1016/j.scitotenv.2018.01.310 [2] 曹红. 污染场地有机污染物迁移转化规律及其含水层系统天然净化能力研究[D]. 济南: 山东科技大学, 2010. [3] 马长文. 地下水中四氯乙烯迁移归宿与修复技术研究[D]. 上海: 上海交通大学, 2007. [4] SATO C, YAO J. Simultaneous and sequential photosonolysis of TCE and PCE[J]. Journal of Environmental Engineering-Asce, 2006, 132(1): 32-41. doi: 10.1061/(ASCE)0733-9372(2006)132:1(32) [5] 方生, 陈秀玲. 地下水开发引起的环境问题与治理[J]. 南水北调与水利科技, 2001, 23(1): 8-11. [6] 吕倩, 魏洁云. 中国地下水污染现状及治理[J]. 生态经济, 2016, 32(10): 10-13. doi: 10.3969/j.issn.1671-4407.2016.10.003 [7] LUO Y S, HSIEH N H, SOLDATOW V Y, et al. Comparative analysis of metabolism of trichloroethylene and tetrachloroethylene among mouse tissues and strains[J]. Toxicology, 2018, 409: 33-43. doi: 10.1016/j.tox.2018.07.012 [8] MAHALINGAIAH S, WINTER M R, ASCHENGRAU A. Association of prenatal and early life exposure to tetrachloroethylene (PCE) with polycystic ovary syndrome and other reproductive disorders in the cape cod health study: A retrospective cohort study[J]. Reproductive Toxicology, 2016, 65: 87-94. doi: 10.1016/j.reprotox.2016.07.005 [9] 杨钦明. 四氯乙烯污染地下水的厌氧-好氧型生物反应格栅修复技术研究[D]. 天津: 天津大学, 2017. [10] 周友亚, 颜增光, 周光辉, 等. 制定场地土壤风险评价筛选值中关注污染物的预筛选方法[J]. 环境工程技术学报, 2011, 1(3): 264-269. doi: 10.3969/j.issn.1674-991X.2011.03.044 [11] WU M, LUO Q, LIU S, et al. Screening ornamental plants to identify potential Cd hyperaccumulators for bioremediation[J]. Ecotoxicology and Environmental Safety, 2018, 162: 35-41. doi: 10.1016/j.ecoenv.2018.06.049 [12] DAVID M M, CECILLON S, WARNE B M, et al. Microbial ecology of chlorinated solvent biodegradation[J]. Environmental Microbiology, 2015, 17(12): 4835-4850. doi: 10.1111/1462-2920.12413 [13] 宋震宇, 杨伟, 王文茜, 等. 氯代烃污染地下水修复技术研究进展[J]. 环境科学与管理, 2014, 39(4): 95-99. doi: 10.3969/j.issn.1673-1212.2014.04.024 [14] CHANG C H, YANG H Y, HUNG J M, et al. Simulation of combined anaerobic/aerobic bioremediation of tetrachloroethylene in groundwater by a column system[J]. International Biodeterioration & Biodegradation, 2017, 117: 150-157. [15] 米生权, 魏涛. 四氯乙烯污染现状及处理方法的研究进展[J]. 海峡预防医学杂志, 2006, 12(3): 21-23. doi: 10.3969/j.issn.1007-2705.2006.03.007 [16] 马长文, 仵彦卿, 孙承兴. 受氯代烃类污染的地下水环境修复研究进展[J]. 环境保护科学, 2007, 33(3): 23-25. doi: 10.3969/j.issn.1004-6216.2007.03.008 [17] LEE J, LEE T K. Development and characterization of PCE-to-ethene dechlorinating microcosms with contaminated river sediment[J]. Journal of Microbiology and Biotechnology, 2016, 26(1): 120-129. doi: 10.4014/jmb.1510.10026 [18] DING C, ALVAREZ C L, HE J. Growth of Dehalococcoides mccartyi species in an autotrophic consortium producing limited acetate[J]. Biodegradation, 2018, 29(5): 487-498. doi: 10.1007/s10532-018-9846-9 [19] MATTURRO B, FRASCADORE E, ROSSETTI S. High-throughput sequencing revealed novel Dehalococcoidia in dechlorinating microbial enrichments from PCB-contaminated marine sediments[J]. FEMS Microbiology Ecology, 2017, 93(11): 134. [20] 李烨. 不同厌氧环境中四氯乙烯生物降解研究[D]. 北京: 中国地质大学, 2006. [21] GULLOTTA F, DI M A, COLETTA M, et al. Co metabolism, sensing, and signaling[J]. Biofactors, 2012, 38(1): 1-13. doi: 10.1002/biof.v38.1 [22] 史敬华. 不同基质共代谢降解地下水中四氯乙烯的研究[D]. 北京: 中国地质大学, 2006. [23] HATZINGER P B, STREGER S H, BEGLEY J F. Enhancing aerobic biodegradation of 1,2-dibromoethane in groundwater using ethane or propane and inorganic nutrients[J]. Journal of Contaminant Hydrology, 2015, 172: 61-70. doi: 10.1016/j.jconhyd.2014.11.006 [24] 范平, 宋天顺, 覃彪, 等. 不同驯化方式对以苯酚为基质的微生物燃料电池产电性能的影响[J]. 环境工程学报, 2012, 6(11): 3867-3872. [25] 袁芳. 2,4-二硝基甲苯的微生物共代谢降解研究[D]. 南京: 南京理工大学, 2012. [26] 夏至. 纳米钯/铁/PVDF-g-(聚)丙烯酸催化还原剂制备及其脱氯性能研究[D]. 哈尔滨: 哈尔滨工业大学, 2013. [27] LI C, TANG L, PENG J, et al. Determination of trichloroethylene and tetrachloroethylene in Li river sediments by headspace gas chromatography[J]. The Administration and Technique of Environmental Monitoring, 2017, 29(5): 44-46. [28] SCHLOSS P D, WESTCOTT S L, RVABIN T, et al. Introducing mothur: Open-source, platform-independent, community-supported software for describing and comparing microbial communities[J]. Applied and Environmental Microbiology, 2009, 75(23): 7537-7541. doi: 10.1128/AEM.01541-09 [29] MAO Y P, XIA Y, ZHANG T. Characterization of Thauera-dominated hydrogen-oxidizing autotrophic denitrifying microbial communities by using high-throughput sequencing[J]. Bioresource Technology, 2013, 128: 703-710. doi: 10.1016/j.biortech.2012.10.106 [30] LOFFLER F E, SUN Q, LI J, et al. 16S rRNA gene-based detection of tetrachloroethene-dechlorinating Desulfuromonas and Dehalococcoides species[J]. Applied and Environmental Microbiology, 2000, 66(4): 1369-1374. doi: 10.1128/AEM.66.4.1369-1374.2000 [31] 晁红军, 宋修鹏, 孙继华, 等. 甲基营养菌的研究进展[J]. 微生物学通报, 2009, 36(11): 1727-1737. [32] CHAIGNAUD P, MAUCOURT B, WEIMAN M, et al. Genomic and transcriptomic analysis of growth-supporting dehalogenation of chlorinated methanes in Methylobacterium[J]. Frontiers in Microbiology, 2017, 8(9): 1600. [33] KITTICHOTIRAT W, GOOD N M, HALL R, et al. Genome sequence of Methyloversatilis universalis FAM5(T), a methylotrophic representative of the order Rhodocyclales[J]. Journal of Bacteriology, 2011, 193(17): 4541-4542. doi: 10.1128/JB.05331-11 [34] ZEMB O, LEE M, LOW A, et al. Reactive iron barriers: A niche enabling microbial dehalorespiration of 1,2-dichloroethane[J]. Applied Microbiology and Biotechnology, 2010, 88(1): 319-325. doi: 10.1007/s00253-010-2740-y [35] GROSTERN A, EDWARDS E A. A 1,1,1-trichloroethane-degrading anaerobic mixed microbial culture enhances biotransformation of mixtures of chlorinated ethenes and ethanes[J]. Applied and Environmental Microbiology, 2006, 72(12): 7849-7856. doi: 10.1128/AEM.01269-06 [36] ZHANG H, ZIV-EL M, RITTMANN B E, et al. Effect of dechlorination and sulfate reduction on the microbial community structure in denitrifying membrane-biofilm reactors[J]. Environmental Science & Technology, 2010, 44(13): 5159-5164. [37] TONG H, CHEN M, LI F, et al. Changes in the microbial community during repeated anaerobic microbial dechlorination of pentachlorophenol[J]. Biodegradation, 2017, 28(2/3): 219-230. [38] PRUDEN A, SUIDAN M T, VENOSA A D, et al. Biodegradation of methyl tert-butyl ether under various substrate conditions[J]. Environmental Science & Technology, 2001, 35(21): 4235-4241. [39] YANG G, CHEN M, ZHOU S, et al. Sinorhodobacter ferrireducens gen. nov., sp nov., a non-phototrophic iron-reducing bacterium closely related to phototrophic Rhodobacter species[J]. Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology, 2013, 104(5): 715-724. doi: 10.1007/s10482-013-9979-0 [40] NUNOURA T, HIRAI M, MIYAZAKI M, et al. Isolation and characterization of a thermophilic, obligately anaerobic and heterotrophic marine Chloroflexi bacterium from a Chloroflexi-dominated microbial community associated with a Japanese shallow hydrothermal system, and proposal for Thermomarinilinea lacunofontalis gen. nov., sp nov[J]. Microbes and Environments, 2013, 28(2): 228-235. doi: 10.1264/jsme2.ME12193 [41] ZHANG Y, HU M, LI P, et al. Trichloroethylene removal and bacterial variations in the up-flow anaerobic sludge blanket reactor in response to temperature shifts[J]. Applied Microbiology and Biotechnology, 2015, 99(14): 6091-6102. doi: 10.1007/s00253-015-6480-x [42] SHARMA P, SCHIEWER S. Assessment of crude oil biodegradation in arctic seashore sediments: Effects of temperature, salinity, and crude oil concentration[J]. Environmental Science and Pollution Research, 2016, 23(15): 14881-14888. doi: 10.1007/s11356-016-6601-9 [43] 隋淑梅, 尹志刚, 姜利国, 等. 考虑地下水温度的土壤吸附氨氮动力学行为研究[J]. 水资源与水工程学报, 2016, 27(3): 217-220. [44] 黄景锐. 西安市浅层地温场分布特征及其变化分析[D]. 西安: 长安大学, 2013. [45] 李志红. 银川平原浅层地温场和水化学特征及其影响因素研究[D]. 北京: 中国地质大学, 2014. [46] 周群英, 王士芬. 环境工程微生物学[M]. 北京: 高等教育出版社, 2008. [47] 陶亚奇, 蒋卓睿, 陈雪. 类Fenton试剂处理苯酚废水的影响因素及动力学研究[J]. 南京农业大学学报, 2012, 35(4): 126-129. [48] 宁静. 乙醇条件下简单节杆菌细胞性质的变化及其对物质跨细胞运输的影响[D]. 天津: 天津科技大学, 2013. [49] 朱敏. 乙醇胁迫对乳酸杆菌代谢活力及膜结构的影响[D]. 石河子: 石河子大学, 2015. [50] LEGARTH J H O F. Antibacterial composition or antibacterial ingredient useful for treating, alleviating and/or preventing growth of gram-positive bacteria including Clostridium bacteria or Streptococcus bacteria, comprises a seaweed material: WO2017186927-A1[P]. 2017-11-02.