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Fu J, Zhang S, Ji L, Xu X, Jiao W, Chen T, Li X, Zhan M. State of the art in self-sustaining smoldering for remediation of contaminated soil and disposal of organic waste. JOURNAL OF HAZARDOUS MATERIALS 2024; 474:134667. [PMID: 38820755 DOI: 10.1016/j.jhazmat.2024.134667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 05/15/2024] [Accepted: 05/19/2024] [Indexed: 06/02/2024]
Abstract
Smoldering combustion applications in energy and environmental fields have attracted increasing research attention in recent years. Smoldering has demonstrated considerable green advantages, such as having a low carbon footprint and being sustainable, for remediation of organic-contaminated soil and disposal of high-moisture, low-calorific value, slurry-type organic waste due to its self-sustaining reaction characteristic. This review aims to analyze and summarize studies on smoldering applications to refine the critical components of applied smoldering systems, key reaction characteristics, and corresponding influencing conditions that affect their effectiveness. Furthermore, the common characteristics and influencing factors of different smoldering application scenarios are compared to provide a comprehensive reference for commercial applications. Thus, this paper specifically includes an overview of the impact of inert porous media, combustible material, and oxidants in applied smoldering systems; a review of the research status of the three key reaction characteristics, including peak temperature, smoldering front propagation velocity, and self-sustainability; a summary of typical influencing factors, disposal material characteristics, and control conditions in the two mainstream application directions, which are remediation of contaminated soil and disposal of organic waste; and a comparative analysis of the common modes of applied smoldering beyond the lab scale. As a technically effective and energy-efficient emerging technology, the prospects of smoldering as a robust treatment process in environmental pollution cleanup are presented.
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Affiliation(s)
- Jianying Fu
- State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, Zhejiang Province, China
| | - Shengdong Zhang
- College of Energy Environment and Safety Engineering, China Jiliang University, Hangzhou 310018, Zhejiang Province, China
| | - Longjie Ji
- Beijing Construction Engineering Group Environmental Remediation Co.Ltd., 100015, Beijing, China
| | - Xu Xu
- College of Energy Environment and Safety Engineering, China Jiliang University, Hangzhou 310018, Zhejiang Province, China
| | - Wentao Jiao
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Haidian District, 100085 Beijing, China.
| | - Tong Chen
- State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, Zhejiang Province, China
| | - Xiaodong Li
- State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, Zhejiang Province, China
| | - Mingxiu Zhan
- College of Energy Environment and Safety Engineering, China Jiliang University, Hangzhou 310018, Zhejiang Province, China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Haidian District, 100085 Beijing, China.
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Fournie T, Rashwan TL, Switzer C, Gerhard JI. Smouldering to treat PFAS in sewage sludge. WASTE MANAGEMENT (NEW YORK, N.Y.) 2023; 164:219-227. [PMID: 37084670 DOI: 10.1016/j.wasman.2023.04.008] [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: 10/30/2022] [Revised: 03/10/2023] [Accepted: 04/04/2023] [Indexed: 05/03/2023]
Abstract
Wastewater treatment plants are accumulation points for per- and polyfluoroalkyl substances (PFAS), and are threfore important facilities for PFAS treatment. This study explored using smouldering combustion to treat PFAS in sewage sludge. Base case experiments at the laboratory scale (LAB) used dried sludge mixed with sand. High moisture content (MC) LAB tests, 75% MC sludge by mass, explored impacts of MC on treatment and supplemented with granular activated carbon (GAC) to achieve sufficient temperatures for thermal destruction of PFAS. Additional LAB tests explored using calcium oxide (CaO) to support fluorine mineralization. Further tests performed at an oil-drum scale (DRUM) assessed scale on PFAS removal. Pre-treatment sludge and post-treatment ash samples from all tests were analyzed for 12 PFAS (2C-8C). Additional emissions samples were collected from all LAB tests and analyzed for 12 PFAS and hydrogen fluoride. Smouldering removed all monitored PFAS from DRUM tests, and 4-8 carbon chain length PFAS from LAB tests. For base case tests, PFOS and PFOA were completely removed from sludge; however, high contents in the emissions (79-94% of total PFAS by mass) showed volatilization without degradation. Smouldering high MC sludge at ∼ 900 °C (30 g GAC/kg sand) improved PFAS degradation compared to treatment below 800 °C (<20 g GAC/kg sand). Addition of CaO before smouldering reduced PFAS content in emissions by 97-99% by mass; with minimal PFAS retained in the ash and minimal hydrofluoric acid (HF) production, as the fluorine from the PFAS was likely mineralized in the ash. Co-smouldering with CaO had dual benefits of removing PFAS while minimizing other hazardous emission by-products.
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Affiliation(s)
- T Fournie
- Department of Civil and Environmental Engineering, Western University, N6A 5B9 London, ON, Canada.
| | - T L Rashwan
- Department of Civil and Environmental Engineering, Western University, N6A 5B9 London, ON, Canada; School of Engineering & Innovation, The Open University, Milton Keynes MK7 6AA, UK(1).
| | - C Switzer
- Department of Civil and Environmental Engineering, University of Strathclyde, G1 1XJ Glasgow, UK.
| | - J I Gerhard
- Department of Civil and Environmental Engineering, Western University, N6A 5B9 London, ON, Canada
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