EFFECT OF PYROLYSIS TIME ON PAHS CONTENT AND TOXICITY IN SLUDGE-BASED BIOCHAR
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摘要: 污泥基生物炭作为土壤改良剂,为污泥提供了一种可持续的资源化利用技术。但由于其中可能含有多环芳烃(PAHs)、重金属等污染物,具有潜在的环境风险,如何制备环境友好的生物炭成为后续利用的先决条件。设置热解温度为500℃,升温速率为10℃/min时,采用4种不同热解时间(1~4 h)制备污泥基生物炭,通过提取测试发现热解后PAHs均明显小于原污泥中的含量;各组分含量及PAHs总量均随着热解时间的增加先增大后减小。2 h的热解时间利于原污泥中有机质充分反应生成新的PAHs,因此PAHs总量达到最大值,超过农用限制;但由于未检出毒性最强的BaP及DahA,其毒性当量(TEQs)反而最低。1 h热解时间虽PAHs总量未超过农用标准,但TEQs最大,超过国际生物炭协会规定的阈值。综合PAHs含量和TEQs的限值,热解时间3,4 h制备的污泥基生物炭更具安全性。从节约能源的角度出发,建议选用3 h作为污泥基生物炭的热解时间。Abstract: Sludge-based biochar obtained from pyrolyzing sludge under anaerobic conditions can be used as soil amendment to improve contaminated soil. However, the possible pollutants, such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals have potential environmental risks. The preparing of the environment-friendly biochar has become a prerequisite for subsequent utilization. In this research, four kinds of sludge-based biochar samples were respectively prepared at the different pyrolysis time (1~4 hours) under 500℃. It was found that the PAHs content in sludge-based biochar was significantly less than that in the raw sludge. The concentration of 4 kinds of PAHs (2~5 rings of PAHs) in the 4 kinds of sludge-based biochar increased firstly and then decreased with the pyrolysis duration increasing and reached the maximum in 2 hours, however the concentration of Σ16PAHs exceeded the agricultural limit. It showed that the duration of 2 hours was conducive to the full reaction of the organic matters in the original sludge to form new PAHs, and it also provided sufficient reaction time for the condensation of low-ring aromatic hydrocarbons to high-ring aromatic hydrocarbons. Since the most toxic BaP and DahA were not detected in the biochar during 2 hours, its corresponding toxic equivalents (TEQs) were also the lowest. Although the concentration in 1 hour did not exceed the agricultural standard in China, the TEQs was the highest, exceeding the threshold specified by the International Biochar Association. Considering the PAHs content and TEQs limit, the sludge based biochar prepared by pyrolysis time of 3 hours and 4 hours was much safer. From the perspective of energy conservation, 3 hours pyrolysis time were recommended.
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Key words:
- sludge-based biochar /
- PAHs /
- pyrolysis time /
- toxicity
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[1] 莫测辉,蔡全英,吴启堂,等. 我国一些城市污泥中多环芳烃(PAHs)的研究[J].环境科学学报,2001,21(5):613-618. [2] SONG X D, XUE X Y, CHEN D Z, et al. Application of biochar from sewage sludge to plant cultivation:influence of pyrolysis temperature and biochar-to-soil ratio on yield and heavy metal accumulation[J]. Chemosphere, 2014, 109(8):213-220. [3] MENDEZ A, GOMEZ A, PAZ-FERREIRO J, et al. Effects of sewage sludge biochar on plant metal availability after application to a Mediterranean soil[J]. Chemosphere, 2012, 89(11):1354-1359. [4] MAGDALENA, STEFANIUK, PATRYK, et al. Addition of biochar to sewage sludge decreases freely dissolved PAHs content and toxicity of sewage sludge-amended soil[J]. Environmental Pollution, 2016, 218(11):242-251. [5] SAJJAD HAZRATI, MOHSEN FARAHBAKHSH, ARTEMI CERDÀ, et al. Functionalization of ultrasound enhanced sewage sludge-derived biochar:physicochemical improvement and its effects on soil enzyme activities and heavy metals availability[J]. Chemosphere, 2021,269:128767. [6] CHANG Y C, XIAO X F, HUANG H J, et al. Transformation characteristics of polycyclic aromatic hydrocarbons during hydrothermal liquefaction of sewage sludge[J]. The Journal of Supercritical Fluids, 2020,170(8):105158. [7] WANG H, XU J, SHENG L. Preparation of ceramsite from municipal sludge and its application in water treatment:A review[J]. Journal of Environmental Management, 2021,287(6):112374. [8] XING J, XU G R, LI G B. Comparison of pyrolysis process, various fractions and potential soil applications between sewage sludge-based biochars and lignocellulose-based biochars[J]. Ecotoxicology and Environmental Safety, 2021, 208:111756. [9] FIGUEIREDO C, REIS A, ARAUJO A, et al. Assessing the potential of sewage sludge-derived biochar as a novel phosphorus fertilizer:influence of extractant solutions and pyrolysis temperatures[J]. Waste Management, 2021, 124(1/2):144-153. [10] 刁韩杰,张进,王敏艳,等. 高温热解对污泥炭特性及其重金属形态变化的影响[J].环境工程,2019,37(3):29-34. [11] LENG L J, YUAN X Z, HUANG H J, et al. The migration and transformation behavior of heavy metals during the liquefaction process of sewage sludge[J]. Bioresource Technology, 2014, 167:144-150. [12] YANG Y Q, CUI M H, REN Y G, et al. Towards understanding the mechanism of heavy metals immobilization in biochar derived from co-pyrolysis of sawdust and sewage sludge[J]. Bulletin of Environmental Contamination and Toxicology, 2020, 104(4):489-496. [13] WANG X D, CHANG W C, LI Z W, et al. Co-pyrolysis of sewage sludge and organic fractions of municipal solid waste:synergistic effects on biochar properties and the environmental risk of heavy metals[J]. Journal of Hazardous Materials, 2021, 412:125200. [14] 逯朝锋. 污泥快速热解特性及技术经济性评价[D]. 武汉:华中科技大学, 2016. [15] 黄蓉,刘立恒,何东薇,等. 热解条件对硫酸钙/污泥基生物炭中Pb,Ni形态分布及生态风险的影响[J].环境污染与防治,2020,42(7):849-853. [16] TSAI P J, SHIEH H Y, LEE W J, et al. Health-risk assessment for workers exposed to polycyclic aromatic hydrocarbons (PAHs) in a carbon black manufacturing industry[J]. Science of the Total Environment, 2001, 278(1/2/3):137-150. [17] 戴前进. 污泥热处置过程中二噁英和多环芳烃的排放特性研究[D].杭州:浙江大学,2015. [18] 刘丽,范世锁,张锡涛,等. 城市污泥和水稻秸秆生物炭中多环芳烃的含量及毒性评价[J]. 生态环境学报, 2020, 29(9):166-174. [19] ZIELINSKA A, OLESZCZUK P. The conversion of sewage sludge into biochar reduces polycyclic aromatic hydrocarbon content and ecotoxicity but increases trace metal content[J]. Biomass & Bioenergy, 2015, 75(4):235-244. [20] CHEN X Y, YANG L, MYNENI S, et al. Leaching of polycyclic aromatic hydrocarbons (PAHs) from sewage sludge-derived biochar[J]. Chemical Engineering Journal, 2019,373:840-845. [21] HALE S E, LEHMANN J, RUTHERFORD D, et al. Quantifying the Total and Bioavailable Polycyclic Aromatic Hydrocarbons and Dioxins in Biochars[J]. Environmental Science & Technology, 2012, 46(5):2830-2838. [22] 姜秀艳. 污泥基生物炭制备表征及土壤改良应用研究[D].哈尔滨:哈尔滨工业大学,2014. [23] 王重庆,王晖,江小燕,等.生物炭吸附重金属离子的研究进展[J].化工进展,2019,38(1):692-706. [24] XU Q Y, TANG S Q, WANG J C, et al. Pyrolysis kinetics of sewage sludge and its biochar characteristics[J]. Process Safety and Environmental Protection, 2018,115:49-56. [25] 戴中民. 生物炭对酸化土壤的改良效应与生物化学机理研究[D]. 杭州:浙江大学, 2017. [26] 刘宁. 生物炭的理化性质及其在农业中应用的基础研究[D]. 沈阳:沈阳农业大学, 2014. [27] 环境保护部.土壤和沉积物多环芳烃的测定高效液相色谱法:HJ 784-2016[S]:北京:中国环境科学出版社,2016. [28] 罗飞,宋静,陈梦舫. 油菜饼粕生物炭制备过程中多环芳烃的生成、分配及毒性特征[J].农业环境科学学报,2016, 35(11):2210-2215. [29] 江娟.污泥基生物炭农用的多环芳烃环境行为与温室气体排放影响的研究[D]. 福州:福建师范大学, 2018. [30] NISBET I C T, LAGOY P K. Toxic equivalency factors (TEFs) for polycyclic aromatic hydrocarbons (PAHs)[J]. Regulatory Toxicology & Pharmacology Rtp,1992,16(3):290-300. [31] 肖凯丽. 不同热解温度小麦秸秆生物炭对土壤中多环芳烃环境行为的影响[D].天津:天津大学,2018. [32] 陈梅,王芳, 张德俐. 生物碳结构性质对氨氮的吸附特性的影响[J]. 环境科学, 2019, 40(12):5421-5429. [33] 刘宁. 生物炭的理化性质及其在农业中应用的基础研究[D]. 沈阳:沈阳农业大学, 2014. [34] 袁帅,赵立欣,孟海波,等. 生物炭主要类型、理化性质及其研究展望[J]. 植物营养与肥料学报, 2016, 22(5):1402-1407. [35] 周宏仓,金保升,仲兆平,等. 燃煤流化床多环芳烃的研究现状[J].锅炉技术,2003(5):22-26. [36] International Biochar Initiative. IBI Biochar Certification Program Manual Requirements and Procedures for IBI biochar Certification[G]. 2015. [37] 国家市场监督管理总局.农用污泥污染物控制标准:GB 4284-2018[S]:北京:中国标准出版社,2018:1-5.
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