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Duan Y, Liu X, Ma X, Hong W, Lv G, Jiang X. Comparison and mechanism analysis of MgO, CaO, and Portland cement for immobilization of heavy metals in MSWI fly ash. WASTE MANAGEMENT (NEW YORK, N.Y.) 2024; 187:285-295. [PMID: 39083851 DOI: 10.1016/j.wasman.2024.07.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 07/01/2024] [Accepted: 07/23/2024] [Indexed: 08/02/2024]
Abstract
The significant production of municipal solid waste incineration fly ash (MSWI FA) underscores the importance of developing efficient solidification materials. This study employed MgO and CaO for immobilizing MSWI FA (with a 70% fly ash incorporation), and the immobilization effect was compared with that of Portland cement (PC). Experimental findings revealed that MgO exhibited the most effective stabilization for heavy metals (Cd, Cu, Pb, and Zn) compared to CaO and PC. XRD, FTIR, TG, and SEM analysis indicated that the principal hydration products in MSWI FA binders solidified with MgO, CaO, and PC were Mg(OH)2, CaCO3, and C-S-H gel, respectively. Mg(OH)2 efficiently immobilized heavy metals through chemical complexation and surface adsorption mechanisms. The MgO-treated MSWI FA demonstrated the highest residual fractions and the lowest easily leachable fractions. Moreover, the leaching characteristics of heavy metals were significantly influenced by the pH level, so MgO-treated MSWI FA with a leachate pH of 9.18 achieved the precipitation and stabilization of most heavy metals. In summary, this study provided an effective material selection for MSWI FA immobilization and presented a novel strategy for MSWI FA management.
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Affiliation(s)
- Yin Duan
- State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China; Zhejiang University Qingshanhu Energy Research Center, Linan, Hangzhou 311305, China
| | - Xiaobo Liu
- State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China; Zhejiang University Qingshanhu Energy Research Center, Linan, Hangzhou 311305, China
| | - Xiaojun Ma
- Zhejiang Environmental Protection Group Co., Ltd., Zhejiang Development Building, No. 18, Wensan Road, Xihu District, Hangzhou 310012, China
| | - Wenjuan Hong
- State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China; Zhejiang University Qingshanhu Energy Research Center, Linan, Hangzhou 311305, China
| | - Guojun Lv
- State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China; Zhejiang University Qingshanhu Energy Research Center, Linan, Hangzhou 311305, China; Key Laboratory of Clean Energy and Carbon Neutrality of Zhejiang Province, Jiaxing Research Institute, Zhejiang University, 1300 Dongshengxilu Road, Jiaxing 314031, China
| | - Xuguang Jiang
- State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China; Zhejiang University Qingshanhu Energy Research Center, Linan, Hangzhou 311305, China; Key Laboratory of Clean Energy and Carbon Neutrality of Zhejiang Province, Jiaxing Research Institute, Zhejiang University, 1300 Dongshengxilu Road, Jiaxing 314031, China.
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Ma Q, Lei J, He J, Chen Z, Li W. Epoxy resin for solidification/stabilization of soil contaminated with copper (II): Leaching, mechanical, and microstructural characterization. ENVIRONMENTAL RESEARCH 2024; 240:117512. [PMID: 37914008 DOI: 10.1016/j.envres.2023.117512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 10/20/2023] [Accepted: 10/24/2023] [Indexed: 11/03/2023]
Abstract
Among different types of heavy metal-contaminated soil, copper (Cu)-contaminated soil is very serious, and the Cu concentration in it is usually very high. It is common to solidify/stabilize Cu-contaminated soil using alkaline cementitious material. However, the remediated Cu-contaminated soil fails to meet the requirements of environmental safety and load-bearing capacity. This dilemma in the remediation of Cu-contaminated soil hinders the effective utilization of land resources. In this study, epoxy resin (EP) was utilized to solidify/stabilize Cu-contaminated soil due to its stable and rapid curing performance and excellent resistance to acid, alkali, and salt erosion. The mechanical properties, environmental effects, and curing mechanism of EP-cured Cu-contaminated soil were investigated. The results showed that the application of EP significantly enhanced the unconfined compressive strength (UCS), cohesion and internal friction angle of Cu-contaminated soil. All specimens met the UCS criterion specified by the United States Environmental Protection Agency (USPEA), namely no less than 0.35 MPa, which indicated that those EP-cured Cu-contaminated soil were qualified for practical engineering applications. According to the toxicity characteristic leaching procedure (TCLP), the application of EP enhanced the stability of Cu in Cu-contaminated soil. The leaching index of Cu ranged from 11 to 14. A high leaching index showed that the S/S treatment was safe and effective and the remediated Cu-contaminated soil satisfied the environmental requirement for heavy metals. This study confirmed the feasibility of utilizing EP in the solidification/stabilization (S/S) technology to convert high-concentration Cu-contaminated soil into secure and stable engineering materials. The remediation of Cu-contaminated soil by EP lays a solid foundation for the safe treatment and reuse of heavy metal-contaminated land resources.
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Affiliation(s)
- Qiang Ma
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, China; Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes, Hubei University of Technology, Wuhan, 430068, China.
| | - Jingjie Lei
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, China; Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes, Hubei University of Technology, Wuhan, 430068, China.
| | - Jun He
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, China; Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes, Hubei University of Technology, Wuhan, 430068, China.
| | - Zhi Chen
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, China; Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes, Hubei University of Technology, Wuhan, 430068, China.
| | - Wentao Li
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, China; Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes, Hubei University of Technology, Wuhan, 430068, China.
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Li W, Qin J, Yi Y. Treating Pb-contaminated clay slurry by three curing agents. CHEMOSPHERE 2022; 303:135011. [PMID: 35609664 DOI: 10.1016/j.chemosphere.2022.135011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 05/03/2022] [Accepted: 05/16/2022] [Indexed: 06/15/2023]
Abstract
Each year, extensive dredged clay slurries containing heavy metals need to be treated before being reused; in such contaminated slurries, lead (Pb) is frequently identified. Quicklime (CaO)-activated ground granulated blast-furnace slag (GGBS), magnesium (MgO)-activated GGBS, and ordinary Portland cement (OPC) are usually used to remediate the lead (Pb)-contaminated soil; nevertheless, using these curing agents (or binders), particularly CaO-GGBS and MgO-GGBS, to treat Pb-contaminated slurry with high water content is rarely reported. Moreover, inconsistent results were obtained from previous studies in terms of the mechanical and leaching performance of Pb-contaminated soils with the three binders. Based on the above-mentioned reasons, this study used CaO-GGBS, MgO-GGBS, and OPC to treat the Pb-contaminated clay slurry, and compared the effectiveness of the three binders in improving the mechanical and leaching properties of the slurry. Laboratory tests were performed to examine the leaching, strength, mineralogical, and micro-structural performance of treated clay slurries. The results showed that GGBS-based binders were more effective than OPC in improving the strength and Pb leachability of contaminated slurries. When suitable ratios between activators (CaO and MgO) and GGBS were used, a similar or even higher UCS was produced by CaO-GGBS than MgO-GGBS. Similar leachate pH and Pb leachability could be achieved between CaO-GGBS- and MgO-GGBS-treated contaminated clay slurries. Therefore, it is not rigorous to state that MgO-GGBS is better in improving the strength and leachability of Pb-contaminated soils than CaO-GGBS only by comparing the two GGBS-binders based on the same activator/GGBS ratio, as reported in some previous studies. The leachability of Pb was affected by the pH, but the addition of GGBS facilitated the decrease of Pb leachability in slurries. The XRD result showed the formation of CSH and Pb(OH)2, which facilitated the reduction of Pb leachability.
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Affiliation(s)
- Wentao Li
- School of Civil Engineering, Architecture and Environment, Hubei University of Technology, 430068, China; School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore; Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes, Hubei University of Technology, 430068, China
| | - Junde Qin
- School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore; Nanyang Environment & Water Research Institute, Nanyang Technological University, 639798, Singapore
| | - Yaolin Yi
- School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore.
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The Effects of Portland and Sulphoaluminate Cements Solidification/Stabilization on Semi-Dynamic Leaching of Heavy Metal from Contaminated Sediment. SUSTAINABILITY 2022. [DOI: 10.3390/su14095681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cement-based solidification/stabilization technology is widely applied in the treatment of heavy metals in river sediment because it is an effective treatment, with the advantages of saving time and being economically and environmentally friendly. In this study, the heavy metal polluted sediment in Shanghai Fuxing Island Canal was used as the raw material, the cement solidified form was prepared by adding 10% Portland cement or sulphoaluminate cement, and semi-dynamic leaching tests were carried out on the solidified forms. In this study, we compare two types of cements as metal conditioners and curing agents aiming to determine the more economical and effective way to utilize river sediments. The results showed that the compressive strength of Portland cement solidified form (PSF) increased with an increase in curing time, which could reach 0.75 MPa after 28 days and met the requirements of general subgrade engineering. The compressive strength of sulphoaluminate cement solidified form (SSF) reached 0.35 MPa after curing for 1 day, however, it decreased later. The semi-dynamic leaching test results showed that the mobility of Cu and Cd in the cement solidified form was low, and the migration mechanism of heavy metals was mainly diffusion. The mobility of heavy metals in the PSF was lower than in the SSF, thus, the PSF had a better solidification effect and was more suitable for treating heavy metal-contaminated sediment.
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Wang M, Liu Y, Qi B, Al-Tabbaa A, Wang W. Assessing the influence of pore structure formation on heavy metal immobilization through image-based CFD. CHEMOSPHERE 2021; 275:129997. [PMID: 33662733 DOI: 10.1016/j.chemosphere.2021.129997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 02/04/2021] [Accepted: 02/13/2021] [Indexed: 06/12/2023]
Abstract
Porous media are widely adopted as immobilization sorbents in environmental engineering. The microscale difference in pore structure formation causes significant deflection in a vast landscape. Computational fluid dynamics (CFD) offers a comparative approach to evaluate the individual influence from pore structure formation with strictly controlled surface and volume properties. This paper presents a comprehensive comparison between the performance of cylindrical media and spherical-media in heavy metal immobilization. Digital testing was performed to measure the surface area, specific surface area, density and porosity. Image-based input technique was developed to reconstruct the cylindrical media. It was found that although the surface area, specific surface area and porosity were the same, the spherical media still had an accelerated immobilization rate. Results further showed that the spherical media in floatation arrangement had an immobilization rate of 16% higher than the cylindrical media with the same surface properties. Non-floatation arrangement of the spherical media caused a reduction in immobilization capacity up to 32.8% lower than the cylindrical media. The cylindrical media demonstrated an advantage of being structurally stable under high porosity, the latter of which resulted in an increased immobilization capacity compared with the spherical-media. The results suggest that the cylindrical bio-microstructure is desirable for heavy metal immobilization in a non-flotational environment. The computational approach provides a digital solution to evaluate the immobilization in 3D architected media. The proposed testing methods are feasible for both experimentally obtained images and structures from algorithm-generation.
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Affiliation(s)
- Mingzhi Wang
- School of Civil Engineering, Harbin Institute of Technology, Harbin, 150090, China; Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education, Harbin Institute of Technology, Harbin, 150090, China; Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology, Harbin Institute of Technology, Harbin, 150090, China.
| | - Yushi Liu
- School of Civil Engineering, Harbin Institute of Technology, Harbin, 150090, China; Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education, Harbin Institute of Technology, Harbin, 150090, China; Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology, Harbin Institute of Technology, Harbin, 150090, China
| | - Beimeng Qi
- College of Quality & Safety Engineering, China Jiliang University, Hangzhou, 310018, China.
| | - Abir Al-Tabbaa
- Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK
| | - Wei Wang
- School of Civil Engineering, Harbin Institute of Technology, Harbin, 150090, China; Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education, Harbin Institute of Technology, Harbin, 150090, China; Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology, Harbin Institute of Technology, Harbin, 150090, China
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Mahedi M, Cetin B, Dayioglu AY. Effect of cement incorporation on the leaching characteristics of elements from fly ash and slag treated soils. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2020; 253:109720. [PMID: 31654932 DOI: 10.1016/j.jenvman.2019.109720] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Revised: 10/04/2019] [Accepted: 10/14/2019] [Indexed: 06/10/2023]
Abstract
Inclusion of cement in fly ash and slag mixed soils could potentially alter the leaching behavior of elements. This study investigated the leaching characteristics of calcium (Ca), magnesium (Mg), sulfur (S), manganese (Mn), barium (Ba) and chromium (Cr) from cement activated soil-fly ash, soil-slag mixtures and soil, fly ash, steel slag and cement alone. Batch water leach tests, acid neutralization capacity and pH-dependent leach tests were performed. Test results indicated that, effluent concentrations of Ca and Ba increased, while Mg concentrations decreased with cement additions. No consistent trend was observed between S concentrations and cement content. The leaching of Cr and Mn remained unaffected by cement incorporation. Results of this study showed that the solution pH had the greatest influence on the leaching behaviors of the elements. Ca, Mg, S and Mn followed cationic leaching patterns, whereas Ba showed both cationic and amphoteric leaching patterns. The highest concentrations of Cr were observed at extreme acidic conditions, followed by a concentration plateau at the pH range of 5.5-10, and subsequent decrease and increase in concentrations at pH of 11.5 and 13, respectively. Geochemical modeling results suggested that except for Cr, the leaching mechanisms of the elements were controlled by their sulfate and (hydr)oxide minerals. The leaching of Cr was possibly controlled by BaCrO4 and CaCrO4. It was observed that the presence of carbonate minerals did not play a significant role on the leaching mechanisms of the elements, when cement was used as an activator.
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Affiliation(s)
- Masrur Mahedi
- Department of Civil, Construction and Environmental Engineering, 813 Bissell Road, Town Engineering Building, Iowa State University, Ames, IA, 50011, USA.
| | - Bora Cetin
- Department of Civil and Environmental Engineering, 428 S. Shaw Lane, Michigan State University, East Lansing, MI, 48824, USA.
| | - Asli Y Dayioglu
- Department of Civil Engineering, 259 School of Civil Engineering, Istanbul Technical University, Istanbul, 34467, Turkey.
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Wang F, Shen Z, Liu R, Zhang Y, Xu J, Al-Tabbaa A. GMCs stabilized/solidified Pb/Zn contaminated soil under different curing temperature: Physical and microstructural properties. CHEMOSPHERE 2020; 239:124738. [PMID: 31494316 DOI: 10.1016/j.chemosphere.2019.124738] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 08/29/2019] [Accepted: 08/30/2019] [Indexed: 06/10/2023]
Abstract
Stabilization/Solidification (S/S) has been widely used in soil remediation to both improve physical properties and immobilize extensive contaminants. GGBS (granulated ground blast furnace slag)-MgO-CaO (GMCs) was used to treat Pb/Zn contaminated soil. The physical and microstructural characteristics of stabilized/solidified contaminated soil were investigated in this study. Microstructural analysis showed that the main hydration products of GMC treated contaminated soil were C-S-H and hydrotalcite like gels (Ht), which dominated the physical strength of S/S soil. The unconfined compressive strength (UCS) and the leachability of GMC treated contaminated soil were improved with the increase in GMC proportion (5%-15%), curing time (7 days and 28 days) and temperature (5 °C, 21 °C and 45 °C) due to the enhanced hydration. The compressive strengths of the majority mixes met the US EPA criterion (0.35 MPa). The strength of S/S soils was less affected by the increase of curing temperature after a longer curing period (28 days). According to the XRD and SEM results, both Pb and Zn in S/S contaminated soil could be immobilized by the precipitation and the adsorption on the surface of calcium silicate hydrate (C-S-H). Zn can also be incorporated into the structure of C-S-H and Ht. The addition of Pb/Zn decreased the physical strength in the order of: Pb(5000 mg/kg)>Pb(10000 mg/kg)>Zn/Pb(5000 mg/kg)>Pb(20000 mg/kg).
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Affiliation(s)
- Fei Wang
- Institute of Geotechnical Engineering, School of Transportation, Southeast University, Nanjing, 210096, China.
| | - Zhengtao Shen
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, T6G 2E3, Canada.
| | - Rongqin Liu
- Institute of Geotechnical Engineering, School of Transportation, Southeast University, Nanjing, 210096, China.
| | - Yunhui Zhang
- Institute of Geotechnical Engineering, School of Transportation, Southeast University, Nanjing, 210096, China; Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ, UK.
| | - Jian Xu
- Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing, 210042, PR China.
| | - Abir Al-Tabbaa
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ, UK.
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Wang F, Zhang Y, Shen Z, Pan H, Xu J, Al-Tabbaa A. GMCs stabilized/solidified Pb/Zn contaminated soil under different curing temperature: leachability and durability. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:26963-26971. [PMID: 31309424 DOI: 10.1007/s11356-019-05894-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 07/01/2019] [Indexed: 06/10/2023]
Abstract
In this study, the impact of the curing temperature on leaching behaviour and durability of GGBS-MgO-CaO (GMC)-stabilized/GMC-solidified Pb/Zn-contaminated clay soils was investigated. Toxicity characteristic leaching procedure (TCLP) test, wetting-drying cycles, freeze-thaw cycles and unconfined compression strength (UCS) test were carried out. The influence of curing temperature, binder dosage and curing time on the performance of these samples was investigated. The results show that the leachability and the durability of all samples were improved by increasing curing temperature, curing time and binder dosage. GMCs are more functional in immobilizing Pb compared with Zn, especially in immobilizing high Pb-contaminated soils. The mass loss and Pb/Zn leachability of all samples increased, while their strength decreased after cyclic wetting-drying and cyclic freeze-thaw. Furthermore, curing at 21 °C and 45 °C, the freeze-thaw resistance of 10% GMC-treated soil (GMC10) was found better than that of 10% Portland cement-treated soil (PC10). After 10 cycles of wetting-drying, GMC10 is more chemically stable than PC10.
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Affiliation(s)
- Fei Wang
- Institute of Geotechnical Engineering, School of Transportation, Southeast University, Nanjing, 210096, China.
| | - Yunhui Zhang
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ, UK
| | - Zhengtao Shen
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, T6G 2E3, Canada
| | - Hao Pan
- Institute of Geotechnical Engineering, School of Transportation, Southeast University, Nanjing, 210096, China
| | - Jian Xu
- Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing, 210042, People's Republic of China.
| | - Abir Al-Tabbaa
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ, UK
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