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Drapanauskaitė D, Barčauskaitė K, Bunevičienė K, Urbonavičius M, Varnagiris Š, Baltrusaitis J. Recovery of nutrients from biofuel ash via organic acid-facilitated solid-liquid extraction. CHEMOSPHERE 2024; 363:142945. [PMID: 39059641 DOI: 10.1016/j.chemosphere.2024.142945] [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: 03/26/2024] [Revised: 07/03/2024] [Accepted: 07/24/2024] [Indexed: 07/28/2024]
Abstract
Solid-liquid extraction was investigated to obtain selected major plant nutrients (P, K, Ca, Mg) from biofuel ash using weak organic acids like salicylic acid, citric acid, and oxalic acid as sacrificial leaching agents. In this study, three organic acids were compared to determine the most effective leaching agent for maximizing the P, K, Ca, and Mg extraction from biofuel ash. The findings indicated that 0.1 M citric acid was the most efficient for plant nutrient recovery, with 81.9% of P recovered after 30 min, 82.4% of Ca, 76.8% of Mg, and 47.3% of K. after 120 min. The highest amount of K, with 59.3% was recovered after 180 min of extraction with 0.1 M oxalic acid. However, recovery of P-80.7% was lower, and much lower recovery of Ca-2.3%, and Mg-68.6% after 180 min of extraction with 0.1 M oxalic acid. The leachates were not contaminated with heavy metals, just 0.47 mg/L of Zn, 7.67 mg/L of Al, and 1.99 mg/L of Fe were detected after 180 min of extraction with 0.1 M oxalic acid. The formation of calcium oxalates after extraction with 0.1 M oxalic acid was seen by SEM-EDS. The findings indicated that to achieve the highest recovery of all beneficial nutrients (P, K, Ca, Mg) different extraction times and different extraction agents are required.
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Affiliation(s)
- Donata Drapanauskaitė
- Lithuanian Research Centre for Agriculture and Forestry, Instituto al.1, LT-58344, Akademija, Kedainiai District, Lithuania.
| | - Karolina Barčauskaitė
- Lithuanian Research Centre for Agriculture and Forestry, Instituto al.1, LT-58344, Akademija, Kedainiai District, Lithuania
| | - Kristina Bunevičienė
- Lithuanian Research Centre for Agriculture and Forestry, Instituto al.1, LT-58344, Akademija, Kedainiai District, Lithuania
| | - Marius Urbonavičius
- Center for Hydrogen Energy Technologies, Lithuanian Energy Institute, 3 Breslaujos, 44403 Kaunas, Lithuania
| | - Šarūnas Varnagiris
- Center for Hydrogen Energy Technologies, Lithuanian Energy Institute, 3 Breslaujos, 44403 Kaunas, Lithuania
| | - Jonas Baltrusaitis
- Department of Chemical and Biomolecular Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA, 18015, USA
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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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3
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Suter EK, Rutto HL, Seodigeng TS, Kiambi SL, Omwoyo WN. Recycled pulp and paper sludge, potential source of cellulose: feasibility assessment and characterization. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2024; 58:1061-1071. [PMID: 38287653 DOI: 10.1080/10934529.2024.2309857] [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: 08/27/2023] [Accepted: 01/17/2024] [Indexed: 01/31/2024]
Abstract
The pulp and paper industry stands out as an example of a technology based on a renewable resource, cellulose. The sludge, however, poses major environmental and public health problems. To effectively manage the sludge wastes, it is critical to fully evaluate its composition, possible environmental impacts, and the total amount of exploitable renewable resources. The study established the pH of the sludge to be 7.32 ± 0.98, an electrical conductivity (1.84 mS/cm), nitrogen concentration (2.65 ± 0.21%), and total organic matter (41.23 ± 3.11%). The cellulosic content was established to be 74.07 ± 2.71% which contributes to 53.07 ± 1.23% water holding capacity (WHC). The most abundant elements were C and O, followed by Cl, Si, Al, and Mg, with lower concentrations of S, Si, K, and iron. The polycyclic aromatic compounds (PAHs) levels ranged from 0.29 to 322.56 ng.g-1 with 1-methyl pyrene posting the highest concentration (322.56 ng.g-1. XRD peaks at 17.10°, 23.86°, 30.14°, and 36.57°, which imply the existence of CaCO3. SEM indicated that the sludge was majorly comprised of fibers materials with average particle sizes of 280 micrometers. TGA/DTG analysis showed that the sludge had the greatest cellulose and hemicellulose (64.7 wt. %).
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Affiliation(s)
- E K Suter
- Department of Chemical Engineering and Metallurgy, Clean Technology and Applied Materials Research Group, Vaal University of Technology, Vanderbijlpark, South Africa
| | - H L Rutto
- Department of Chemical Engineering and Metallurgy, Clean Technology and Applied Materials Research Group, Vaal University of Technology, Vanderbijlpark, South Africa
| | - T S Seodigeng
- Department of Chemical Engineering and Metallurgy, Clean Technology and Applied Materials Research Group, Vaal University of Technology, Vanderbijlpark, South Africa
| | - S L Kiambi
- Department of Chemical Engineering and Metallurgy, Clean Technology and Applied Materials Research Group, Vaal University of Technology, Vanderbijlpark, South Africa
| | - W N Omwoyo
- Biotechnology and Chemistry Department, Vaal University of Technology, Vanderbijlpark, South Africa
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Sun Y, Wang Z, Chen J, Fang Y, Wang L, Pan W, Zou B, Qian G, Xu Y. Phosphorus recovery from incinerated sewage sludge ash using electrodialysis coupled with plant extractant enhancement technology. WASTE MANAGEMENT (NEW YORK, N.Y.) 2023; 164:57-65. [PMID: 37031513 DOI: 10.1016/j.wasman.2023.04.001] [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: 11/24/2022] [Revised: 03/30/2023] [Accepted: 04/01/2023] [Indexed: 06/19/2023]
Abstract
Phosphorus (P) is an integral mineral nutrient for the growth of plants and animals. As the increasing population worldwide, the demand for P resources keeps increasing. Therefore, it is necessary to recover P from secondary resources. Unlike conventional P recovery processes, this work focused on the recovery of P from incinerated sewage sludge ash (ISSA) using electrodialysis as the main technology coupled with plant extractants. In this study, Amaranthus and hydrolyzed polymaleic anhydride (HPMA) were used as P extractants, investigating the effects of HPMA concentration and pH of the compound agent on the migration of P and heavy metals from ISSA. The results showed that the concentration of HPMA and pH of the compound agent had a significant influence on the mobility of P and heavy metals. Meanwhile, the impacts of eggshell additions and voltage on the recovery efficiency of P was also studied by using waste eggshells as calcium sources. We found that when eggshells were added at 10 g/L and the voltage was 10 V, the recovery efficiency of P reached 96.05%. Moreover, XRD patterns revealed that the mineral phase of recovered P-containing products was predominantly hydroxyapatite, which had good environmental benefits. Generally, the favorable results have been achieved in the recovery efficiency of P and has practical implications for P recovery from ISSA.
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Affiliation(s)
- Ying Sun
- School of Environmental and Chemical Engineering, Shanghai University, No. 99, Shangda Road, Shanghai 200444, China
| | - Zexu Wang
- School of Environmental and Chemical Engineering, Shanghai University, No. 99, Shangda Road, Shanghai 200444, China
| | - Jingyan Chen
- School of Environmental and Chemical Engineering, Shanghai University, No. 99, Shangda Road, Shanghai 200444, China
| | - Yangfan Fang
- School of Environmental and Chemical Engineering, Shanghai University, No. 99, Shangda Road, Shanghai 200444, China
| | - Lihua Wang
- School of Environmental and Chemical Engineering, Shanghai University, No. 99, Shangda Road, Shanghai 200444, China
| | - Wei Pan
- School of Environmental and Chemical Engineering, Shanghai University, No. 99, Shangda Road, Shanghai 200444, China
| | - Boyuan Zou
- School of Environmental and Chemical Engineering, Shanghai University, No. 99, Shangda Road, Shanghai 200444, China
| | - Guangren Qian
- School of Environmental and Chemical Engineering, Shanghai University, No. 99, Shangda Road, Shanghai 200444, China.
| | - Yunfeng Xu
- School of Environmental and Chemical Engineering, Shanghai University, No. 99, Shangda Road, Shanghai 200444, China.
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5
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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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Li J, Si M, Dong Z, Huang J, Zhao Q, Li Y, Tian S. Remediation of Cr(VI)-contaminated soil using self-sustaining smoldering. CHEMOSPHERE 2023; 334:138936. [PMID: 37182711 DOI: 10.1016/j.chemosphere.2023.138936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 05/08/2023] [Accepted: 05/12/2023] [Indexed: 05/16/2023]
Abstract
Self-sustaining smoldering is an emerging technology for nonaqueous-phase liquid remediation; however, it is rarely applied for Cr(VI)-contaminated soil treatment. In this study, self-sustaining smoldering using rice straw (RS) as a surrogate fuel was applied to remediate Cr(VI)-contaminated soil for the first time. Thirteen one-dimensional vertical smoldering experiments were conducted to investigate the effectiveness of the smoldering method and the effects of key experimental parameters on smoldering remediation performance. Smoldering was observed to be self-sustaining within the range of RS particle size from <0.16 to 2.00-4.00 mm, airflow from 0.2 to 1 m3/h, and Cr(VI)-impacted soil/RS ratios from 2:1 to 6:1. The Cr(VI)-contaminated soil was effectively remediated, which was confirmed by lowered Cr(VI) contents in the treated samples (decreased by 52.22-86.57%) and the elevated fraction of Cr oxidizable and residual form (increased by 1.14-3.30 and 2.97-4.00 times, respectively), compared to the control. The reducing gases (CO and CxHy) generated during the smoldering played a crucial role in the remediation process. The contents of available P and K in the remediated soil containing the remaining biochar and ash increased, thus improving soil reusability. Hence, this study shows that smoldering with RS as supplemental fuel is a promising Cr(VI)-contaminated soil management technique without supplying substantial external energy.
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Affiliation(s)
- Jie Li
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Meiyan Si
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Zejing Dong
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Jianhong Huang
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China.
| | - Qun Zhao
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Yingjie Li
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Senlin Tian
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China.
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Agrawal R, Bhagia S, Satlewal A, Ragauskas AJ. Urban mining from biomass, brine, sewage sludge, phosphogypsum and e-waste for reducing the environmental pollution: Current status of availability, potential, and technologies with a focus on LCA and TEA. ENVIRONMENTAL RESEARCH 2023; 224:115523. [PMID: 36805896 DOI: 10.1016/j.envres.2023.115523] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 02/06/2023] [Accepted: 02/17/2023] [Indexed: 06/18/2023]
Abstract
Rapid industrialization, improved standards of living, growing economies and ever-increasing population has led to the unprecedented exploitation of the finite and non-renewable resources of minerals in past years. It was observed that out of 100 BMT of raw materials processed annually only 10% is recycled back. This has resulted in a strenuous burden on natural or primary resources of minerals (such as ores) having limited availability. Moreover, severe environmental concerns have been raised by the huge piles of waste generated at landfill sites. To resolve these issues, 'Urban Mining' from waste or secondary resources in a Circular Economy' concept is the only sustainable solution. The objective of this review is to critically examine the availability, elemental composition, and the market potential of the selected secondary resources such as lignocellulosic/algal biomass, desalination water, sewage sludge, phosphogypsum, and e-waste for minerals sequestration. This review showed that, secondary resources have potential to partially replace the minerals required in different sectors such as macro and microelements in agriculture, rare earth elements (REEs) in electrical and electronics industry, metals in manufacturing sector and precious elements such as gold and platinum in ornamental industry. Further, inputs from the selected life cycle analysis (LCA) & techno economic analysis (TEA) were discussed which showed that although, urban mining has a potential to reduce the greenhouse gaseous (GHG) emissions in a sustainable manner however, process improvements through innovative, novel and cost-effective pathways are essentially required for its large-scale deployment at industrial scale in future.
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Affiliation(s)
- Ruchi Agrawal
- TERI-Deakin Nanobiotechnology Centre, Sustainable Agriculture Division, TERI Gram, The Energy and Resources Institute, Gwal Pahari, Gurugram, Haryana, 122103, India.
| | - Samarthya Bhagia
- Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37831, USA.
| | - Alok Satlewal
- Department of Bioenergy, DBT-IOC Centre for Advanced Bioenergy Research, Research and Development Centre, Indian Oil Corporation Ltd, Faridabad, Haryana, 121007, India.
| | - Arthur J Ragauskas
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, 1512 Middle Dr, Knoxville, TN, 37996, USA; Center for Renewable Carbon, Department of Forestry, Wildlife and Fisheries, The University of Tennessee Institution of Agriculture, 2506 Jacob Dr, Knoxville, TN, 37996, USA; Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37831, USA.
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Lan Y, Gai S, Cheng K, Li J, Yang F. Lanthanum carbonate hydroxide/magnetite nanoparticles functionalized porous biochar for phosphate adsorption and recovery: Advanced capacity and mechanisms study. ENVIRONMENTAL RESEARCH 2022; 214:113783. [PMID: 35810808 DOI: 10.1016/j.envres.2022.113783] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 06/06/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
As the increase of global industrial activities, phosphate from industrial wastes such as sewage sludge has become one of the limiting factors for water eutrophication. Herein, lanthanum carbonate hydroxide (La(CO3)OH)/magnetite (Fe3O4) nanoparticles functionalized porous biochar (La/Fe-NBC) with high phosphate adsorption properties is synthesized through molten salt pyrolysis-coprecipitation-hydrothermal multi-step regulation, and further reveal the related processes and mechanisms. La(CO3)OH functions as active sites for phosphate adsorption, Fe3O4 imparts magnetic properties to the composite substance, also porous biochar (NBC) acts as the carrier to prevent the agglomeration of La(CO3)OH and Fe3O4 nanoparticles. The adsorption process of La/Fe-NBC for phosphate fits to the Pseudo-Second Order and Langmuir model, with the theoretical maximum adsorption capacity up to 99.46 mg P/g. And La/Fe-NBC possesses excellent magnetic field (14.50 emu/g), stability, and selectivity, which enables for efficient multiple recovery and reuse. Mechanistic studies have shown that ligand exchange (inner-sphere complexation) between phosphate and carbonate/hydroxyl groups of La(CO3)OH, and electrostatic attraction play the dominant roles during adsorption process, although susceptible to the solution pH. While co-precipitation is not influenced of pH conditions but with limited contribution to phosphate adsorption. This study may facilitate to optimize the synthesis design of phosphate multi-functional composites for low-carbon and sustainable treatment of industrial phosphate-containing wastes.
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Affiliation(s)
- Yibo Lan
- School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin 150030, China; Joint Laboratory of Northeast Agricultural University and Max Planck Institute of Colloids and Interfaces (NEAU-MPICI), Harbin 150030, China
| | - Shuang Gai
- School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin 150030, China; Joint Laboratory of Northeast Agricultural University and Max Planck Institute of Colloids and Interfaces (NEAU-MPICI), Harbin 150030, China
| | - Kui Cheng
- College of Engineering, Northeast Agricultural University, Harbin 150030, China; Joint Laboratory of Northeast Agricultural University and Max Planck Institute of Colloids and Interfaces (NEAU-MPICI), Harbin 150030, China.
| | - Jiangshan Li
- State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Fan Yang
- School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin 150030, China; Joint Laboratory of Northeast Agricultural University and Max Planck Institute of Colloids and Interfaces (NEAU-MPICI), Harbin 150030, China.
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9
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Fournie T, Rashwan TL, Switzer C, Grant GP, Gerhard JI. Exploring PCDD/Fs and potentially toxic elements in sewage sludge during smouldering treatment. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 317:115384. [PMID: 35751238 DOI: 10.1016/j.jenvman.2022.115384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 05/17/2022] [Accepted: 05/20/2022] [Indexed: 06/15/2023]
Abstract
Potentially toxic elements (PTEs), persistent organic pollutants, and emerging contaminants make sewage sludge management challenging. There is significant interest in thermal treatment technologies that can destroy these compounds. The most common thermal treatment, incineration, poses risks due to formation and/or release of hazardous substances in process emissions such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and PTEs. Smouldering has been introduced recently as a potential treatment for managing sewage sludge. Smouldering systems present several advantages over traditional incinerators; however, there are still uncertainties regarding process by-products. This key question was investigated in three laboratory-scale tests (0.08 m radius) and five oil drum-scale tests (0.3 m radius) that were evaluated for PCDD/Fs and PTEs in the mixture before and after treatment as well as in process emissions. Volatile organic compounds (VOCs) were also measured. These experiments represent a broad spectrum of conditions to evaluate process emissions, from robust self-sustaining to extinction of smouldering. Robust smouldering had negligible PCDD/Fs in process emissions. Weak smouldering had low levels of PCDD/Fs (emissions factor: 3.3 ± 0.3 μg TEQ/Mg dried sludge destroyed), levels less than uncontrolled emissions from commercial incinerators. Overall, smouldering acted as a sink for PCDD/Fs, as only 0-3% of the PCDD/Fs originally present in the sludge were released in the emissions, and >99% of the remainder were destroyed with <1% remaining in post-treatment ash. No evidence was found to support de novo synthesis or precursor reactions forming new PCDD/Fs. In addition, 94-100% of all the PTEs analyzed were retained in the post-smouldered material. These results indicate that only minimal emissions treatment for PTEs, PCDD/Fs, and VOCs may be necessary for future sewage sludge smouldering systems. These low emissions risks combined with its unique ability to handle high moisture content waste, indicate that smouldering has significant potential as a valuable waste management technique.
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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; Department of Civil Engineering, Lassonde School of Engineering, York University, Toronto, Ontario, M3J 1P3, Canada
| | - C Switzer
- Department of Civil and Environmental Engineering, University of Strathclyde, G1 1XQ, Glasgow, UK
| | - G P Grant
- Savron, 1243 Islington Ave, Suite 1201, M8X 1Y9, Toronto, ON, Canada
| | - J I Gerhard
- Department of Civil and Environmental Engineering, Western University, N6A 5B9, London, ON, Canada.
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