Migration, transformation and risk assessment of heavy metals in municipal sludge treated by thermal hydrolysis

doi:10.16085/j.issn.1000-6613.2021-0921

Abstract

Abstract:

The effects of different temperatures (120—200℃) and treatment times (15—90min) on the migration transformation and environmental risks of heavy metals (Cr, Mn, Ni, Cu, Cd and Pb) in sludge were investigated by analyzing the changes of heavy metal content and morphology during sludge thermal hydrolysis treatment, and the correlation between physicochemical parameters (VS, soluble protein, polysaccharide, SCOD, alkalinity, ammonia-N, and pH) and changes of heavy metal bioavailability was analyzed. The results showed that the sludge was effectively cracked by thermal hydrolysis, and some of the heavy metals were released into liquid phase, but most of them remained in solid phase. The contents of Cr and Mn in the solid phase increased at higher treatment temperatures (≥180℃) compared to those in the original sludge, while the contents of other heavy metals decreased. Most of the heavy metals (except Pb) in weak acid extracted fraction in sludge showed a decreasing trend with increasing temperature and prolonged time after thermal hydrolysis treatment, while Cr, Ni, Cu, Cd and Pb in residue fraction increased significantly after treatment. The contents of bioavailable heavy metals were strongly correlated to indicators such as ammonia-N, SCOD, soluble protein, and VS. The ecological risk of individual heavy metal was closely related to its migration and transformation, and the risk index of total potential ecological risk of heavy metals in sludge was significantly reduced after thermal hydrolysis treatment.

Key words: sludge, thermal hydrolysis, heavy metals, environmental risk

摘要：

通过分析污泥热水解处理过程中重金属含量与形态的变化，考察不同温度（120~200℃）和不同处理时间（15~90min）对污泥中重金属（Cr、Mn、Ni、Cu、Cd、Pb）迁移转化和环境风险的影响，并对污泥热水解过程中理化参数[挥发性固体（VS）、溶解性蛋白质、多糖、溶解性化学需氧量（SCOD）、碱度、NH₄⁺-N和pH]与重金属生物可利用性变化的相关性进行了分析。结果表明，热水解处理后污泥得到有效破解，部分重金属释放进入液相，但大部分重金属仍残留在固相中。固相中Cr和Mn含量在处理温度较高时（≥180℃）较原泥升高，其他重金属含量均低于原泥。热水解处理后大部分重金属（除Pb外）弱酸提取态占比随处理温度升高和处理时间延长呈下降趋势，且处理后污泥中Cr、Ni、Cu、Cd和Pb残渣态占比明显上升。具有生物有效性重金属含量与污泥NH $4 +$ -N、SCOD、溶解性蛋白质、VS等指标变化有较强相关性。单个重金属生态风险变化与重金属迁移转化密切相关，污泥重金属总潜在生态风险RI在热水解处理后显著降低。

关键词: 污泥, 热水解, 重金属, 环境风险

CLC Number:

X705

FU Jie, QIU Chunsheng, WANG Chenchen, ZHENG Jinxin, LIU Nannan, WANG Dong, WANG Shaopo, SUN Liping. Migration, transformation and risk assessment of heavy metals in municipal sludge treated by thermal hydrolysis[J]. Chemical Industry and Engineering Progress, 2022, 41(4): 2216-2225.

付杰, 邱春生, 王晨晨, 郑金鑫, 刘楠楠, 王栋, 王少坡, 孙力平. 污泥热水解处理过程重金属的迁移转化与风险评价[J]. 化工进展, 2022, 41(4): 2216-2225.

Figures/Tables 11

理化指标	值
TS/g·L^-1	21.73±0.21
VS/g·L^-1	11.92±0.21
pH	7.75±0.01
TCOD/mg·L^-1	17078.56±55.55
SCOD/mg·L^-1	125.52±17.23
NH $4 +$ -N/mg·L^-1	19.11±4.34
溶解性蛋白质/mg·L^-1	32.603±1.48
溶解性多糖/mg·L^-1	12.38±1.64

理化指标	值
TS/g·L^-1	21.73±0.21
VS/g·L^-1	11.92±0.21
pH	7.75±0.01
TCOD/mg·L^-1	17078.56±55.55
SCOD/mg·L^-1	125.52±17.23
NH $4 +$ -N/mg·L^-1	19.11±4.34
溶解性蛋白质/mg·L^-1	32.603±1.48
溶解性多糖/mg·L^-1	12.38±1.64

C_f	重金属污染风险	E_r	潜在生态风险	RI	污泥污染风险
C_f<1	无	E_r<40	低	RI<150	低
1<C_f<3	低	40<E_r<80	中等	150<RI<300	中等
3<C_f<6	中等	80<E_r<160	较高	300<RI<600	较高
6<C_f<9	较高	160<E_r<320	高	RI>600	高
C_f>9	高	E_r>320	极高

**—P<0.01；*—P<0.05

References 35

1	戴晓虎. 城镇污水处理厂污泥稳定化处理的必要性和迫切性的思考[J]. 给水排水, 2017, 53(12): 1-5.
	DAI X H. The necessity and urgency of sludge stabilization treatment in municipal sewage treatment plant[J]. Water & Wastewater Engineering, 2017, 53(12): 1-5.
2	LIU X X, WANG Y W, GUI C M, et al. Chemical forms and risk assessment of heavy metals in sludge-biochar produced by microwave-induced low temperature pyrolysis[J]. RSC Advances, 2016, 6(104): 101960-101967.
3	XU Y, ZHANG C S, ZHAO M H, et al. Comparison of bioleaching and electrokinetic remediation processes for removal of heavy metals from wastewater treatment sludge[J]. Chemosphere, 2017, 168: 1152-1157.
4	ZHEN G Y, LU X Q, KATO H, et al. Overview of pretreatment strategies for enhancing sewage sludge disintegration and subsequent anaerobic digestion: current advances, full-scale application and future perspectives[J]. Renewable and Sustainable Energy Reviews, 2017, 69: 559-577.
5	YUAN X Z, HUANG H J, ZENG G M, et al. Total concentrations and chemical speciation of heavy metals in liquefaction residues of sewage sludge[J]. Bioresource Technology, 2011, 102(5): 4104-4110.
6	解道雷, 孔慈明, 徐龙乾, 等. 城市污泥中重金属存在形态、去除及稳定化研究进展[J]. 化工进展, 2018, 37(1): 330-342.
	XIE D L, KONG C M, XU L Q, et al. Developments of the speciation, removal and stabilization of heavy metals in municipal sludge[J]. Chemical Industry and Engineering Progress, 2018, 37(1): 330-342.
7	郑金鑫, 邱春生, 王晨晨, 等. Fenton处理对污泥脱水性、重金属形态及生物淋滤效率影响[J]. 化工进展, 2020, 39(2): 805-811.
	ZHENG J X, QIU C S, WANG C C, et al. Effects of Fenton treatment on sewage sludge dewaterability, heavy metal speciation and leaching efficiency[J]. Chemical Industry and Engineering Progress, 2020, 39(2): 805-811.
8	LIN K, KUO J H, LIN C L, et al. Sequential extraction for heavy metal distribution of bottom ash from fluidized bed co-combusted phosphorus-rich sludge under the agglomeration/defluidization process[J]. Waste Management & Research, 2020, 38(2): 122-133.
9	RAURET G, LÓPEZ-SÁNCHEZ J F, SAHUQUILLO A, et al. Improvement of the BCR three step sequential extraction procedure prior to the certification of new sediment and soil reference materials[J]. Journal of Environmental Monitoring, 1999, 1(1): 57-61.
10	ZHANG J, TIAN Y, ZHANG J, et al. Distribution and risk assessment of heavy metals in sewage sludge after ozonation[J]. Environmental Science and Pollution Research, 2017, 24(6): 5118-5125.
11	陈思思, 杨殿海, 庞维海, 等. 我国剩余污泥厌氧转化的主要影响因素及影响机制研究进展[J]. 化工进展, 2020, 39(4): 1511-1520.
	CHEN S S, YANG D H, PANG W H, et al. Main influencing factors and mechanisms of anaerobic transformation of excess sludge in China[J]. Chemical Industry and Engineering Progress, 2020, 39(4): 1511-1520.
12	卓杨, 韩芸, 程瑶, 等. 高含固污泥水热预处理中碳、氮、磷、硫转化规律[J]. 环境科学, 2015, 36(3): 1006-1012.
	ZHUO Y, HAN Y, CHEN Y, et al. Transformation characteristics of carbon, nitrogen, phosphorus and sulfur during thermal hydrolysis pretreatment of sludge with high solid content[J]. Environmental Science, 2015, 36(3): 1006-1012.
13	ZHENG J X, QIU C S, WANG C C, et al. Influence of thermal hydrolysis treatment on chemical speciation and bioleaching behavior of heavy metals in the sewage sludge[J]. Water Science and Technology, 2021, 83(2): 372-380.
14	孙雪萍, 王安亭, 李新豪, 等. 热水解法处理污泥过程中重金属的迁移规律[J]. 中国给水排水, 2010, 26(17): 66-68, 72.
	SUN X P, WANG A T, LI X H, et al. Migration of heavy metals in sludge treatment by thermal hydrolysis process[J]. China Water & Wastewater, 2010, 26(17): 66-68, 72.
15	王兴栋, 林景江, 李智伟, 等. 水热处理时间对污泥中氮磷钾及重金属迁移的影响[J]. 环境科学, 2016, 37(3): 1048-1054.
	WANG X D, LIN J J, LI Z W, et al. Effects of hydrothermal treatment time on the transformations of N, P, K and heavy metals in sewage sludge[J]. Environmental Science, 2016, 37(3): 1048-1054.
16	WU H M, LI M, ZHANG L, et al. Research on the stability of heavy metals (Cu, Zn) in excess sludge with the pretreatment of thermal hydrolysis[J]. Water Science and Technology, 2016, 73(4): 890-898.
17	国家环境保护总局《水和废水监测分析方法》编委会. 水和废水监测分析方法[M]. 4版. 北京: 中国环境科学出版社, 2002.
	State Environmental Protection Administration Determination methods for examination of water and wastewater Editorial Board. Determination methods for examination of water and wastewater[M]. 4th ed. Beijing: China Environmental Science Press, 2002.
18	FR/OLUND B, GRIEBE T, NIELSEN P H. Enzymatic activity in the activated-sludge floc matrix[J]. Applied Microbiology and Biotechnology, 1995, 43(4): 755-761.
19	DUBOIS M, GILLES K A, HAMILTON J K, et al. Colorimetric method for determination of sugars and related substances[J]. Analytical Chemistry, 1956, 28(3): 350-356.
20	MARCHIORETTO M M, BRUNING H, RULKENS W. Heavy metals precipitation in sewage sludge[J]. Separation Science and Technology, 2005, 40(16): 3393-3405.
21	HAKANSON L. An ecological risk index for aquatic pollution control—A sedimentological approach[J]. Water Research, 1980, 14(8): 975-1001.
22	HUANG H J, YUAN X Z, ZENG G M, et al. Quantitative evaluation of heavy metals’ pollution hazards in liquefaction residues of sewage sludge[J]. Bioresource Technology, 2011, 102(22): 10346-10351.
23	ZHANG Q, ZHANG L, SANG W J, et al. Chemical speciation of heavy metals in excess sludge treatment by thermal hydrolysis and anaerobic digestion process[J]. Desalination and Water Treatment, 2016, 57(27): 12770-12776.
24	乔玮, 王伟, 黎攀, 等. 城市污水污泥微波热水解特性研究[J]. 环境科学, 2008, 29(1): 152-157.
	QIAO W, WANG W, LI P, et al. Sewage sludge microwave thermal hydrolysis process[J]. Environment Science, 2008, 29(1): 152-157.
25	JEONG S Y, CHANG S W, NGO H H, et al. Influence of thermal hydrolysis pretreatment on physicochemical properties and anaerobic biodegradability of waste activated sludge with different solids content[J]. Waste Management, 2019, 85: 214-221.
26	ZHANG D, FENG Y M, HUANG H B, et al. Recalcitrant dissolved organic nitrogen formation in thermal hydrolysis pretreatment of municipal sludge[J]. Environment International, 2020, 138: 105629.
27	YOSHIDA T, ANTAL M J. Sewage sludge carbonization for terra preta applications[J]. Energy & Fuels, 2009, 23(11): 5454-5459.
28	WEI L L, LI J J, XUE M, et al. Adsorption behaviors of Cu²⁺, Zn²⁺ and Cd²⁺ onto proteins, humic acid, and polysaccharides extracted from sludge EPS: sorption properties and mechanisms[J]. Bioresource Technology, 2019, 291: 121868.
29	于贺, 邱春生, 王晨晨, 等. Fenton预处理对城市污泥重金属形态及生物淋滤溶出影响[J]. 环境工程学报, 2019, 13(3): 725-731.
	YU H, QIU C S, WANG C C, et al. Influence of Fenton pretreatment on heavy metal speciation and bioleaching efficiency in municipal sludge[J]. Chinese Journal of Environmental Engineering, 2019, 13(3): 725-731.
30	WOO S, YUM S, JUNG J H, et al. Heavy metal-induced differential gene expression of metallothionein in Javanese medaka, Oryzias javanicus [J]. Marine Biotechnology, 2006, 8(6): 654-662.
31	ADAM V, PETRLOVA J, POTESIL D, et al. Study of metallothionein modified electrode surface behavior in the presence of heavy metal ions-biosensor[J]. Electroanalysis, 2005, 17(18): 1649-1657.
32	RUDD T, STERRITT R M, LESTER J N. Complexation of heavy metals by extracellular polymers in the activated sludge process [J]. Journal (Water Pollution Control Federation), 1984, 56(12): 1260-1268.
33	甘莉, 刘贺琴, 王清萍, 等. 氧化亚铁硫杆菌生物浸出污泥中的重金属离子[J]. 中国环境科学, 2014, 34(10): 2617-2623.
	GAN L, LIU H Q, WANG Q P, et al. Bioleaching of heavy metals in sewage sludge using Acidithiobacillus ferrooxidans [J]. China Environmental Science, 2014, 34(10): 2617-2623.
34	朱萍, 李晓晨, 马海涛, 等. 污泥中重金属形态分布与可浸出性的相关性研究[J]. 河海大学学报(自然科学版), 2007, 35(2): 121-124.
	ZHU P, LI X C, MA H T, et al. Correlation between chemical forms and leachability of heavy metals in sludge samples[J]. Journal of Hohai University(Natural Sciences), 2007, 35(2): 121-124.
35	ZHENG X R, LIU Y Q, HUANG J M, et al. The influence of variables on the bioavailability of heavy metals during the anaerobic digestion of swine manure[J]. Ecotoxicology and Environmental Safety, 2020, 195: 110457.

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