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Peltola P, Ruottu L, Larkimo M, Laasonen A, Myöhänen K. A novel dual circulating fluidized bed technology for thermal treatment of municipal sewage sludge with recovery of nutrients and energy. WASTE MANAGEMENT (NEW YORK, N.Y.) 2023; 155:329-337. [PMID: 36413885 DOI: 10.1016/j.wasman.2022.11.017] [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: 06/23/2022] [Revised: 10/24/2022] [Accepted: 11/12/2022] [Indexed: 06/16/2023]
Abstract
Sewage sludge (SS), a by-product of the wastewater treatment process, should be viewed not as waste, but as a potential resource for renewable energy and nutrient recovery. However, SS contains various toxic and harmful pollutants, e.g., pathogens, pharmaceutical residues, and microplastics. Through organic recycling and reuse of SS on land, these contaminants may leak into the environment, creating potential hazards to the ecosystem and human health. To tackle this issue, an advanced SS treatment technique within circular economy principles was proposed. In this process, mechanically dewatered SS with 20-25 % total solids is first dried at 110 °C in a circulating fluidized bed dryer and then combusted at 850 °C in a circulating fluidized bed reactor. Consequently, all the unwanted organic compounds are eliminated, and the ash - relatively high in nutrients and sufficiently low in heavy metals - can be further processed into fertilizers and used in forestry or farming. Moreover, the process is self-sufficient in terms of energy, enabling standalone operation without supplementary fuels, and providing excess heat that can be utilized, e.g., as district heat. This paper describes the process in detail and reviews experiences and lessons learned from the commissioning and trial operation of a newly erected 1.5 MWth sludge combustion plant with a throughput of 10 000 t/a. The operational performance of the plant has been verified based on continuous processing of dewatered SS, and the main operating parameters were consistent with design values. Therefore, the scale-up of this technique was considered both feasible and successful.
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Affiliation(s)
- Petteri Peltola
- Endev Ltd., Kluuvikatu 7, FI-00100 Helsinki, Finland; LUT University, P.O. Box 20, FI-53581, Finland.
| | - Lauri Ruottu
- Endev Ltd., Kluuvikatu 7, FI-00100 Helsinki, Finland
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Zheng X, Ying Z, Feng Y, Wang B, Dou B. CaO-assisted hydrothermal treatment combined with incineration of sewage sludge: Focusing on phosphorus (P) fractions, P-bioavailability, and heavy metals behaviors. CHEMOSPHERE 2022; 308:136391. [PMID: 36096311 DOI: 10.1016/j.chemosphere.2022.136391] [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: 06/10/2022] [Revised: 08/23/2022] [Accepted: 09/06/2022] [Indexed: 06/15/2023]
Abstract
Dewatering of sewage sludge (SS) was the prerequisite for saving its drying energy and sustaining its stable combustion. Hydrothermal treatment (HT) has been a promising technology for improving SS dewaterability with high energy efficiency. However, the knowledge of phosphorus (P) transformation and heavy metals (HMs) behaviors in the combined HT and incineration process was still lack. P fractions, P-bioavailability, HMs speciation, and their environmental risk in the ash samples from this combination process were evaluated and compared with those from the co-incineration of SS and CaO. The combination process was superior to the latter one in the light of P and HMs. CaO preferred to enhance the transformation of non-apatite inorganic phosphorus (NAIP) to apatite phosphorus (AP) initially with enriched P and increased P-bioavailability in the resultant ash samples. The combination process further reduced the values of risk assessment code and individual contamination factor with the increment of the stable F4 fraction in HMs. Significant reduction of potential ecological risk was observed with the lowest global risk index of 43.76 in the combination process. Optimum CaO addition of 6% was proposed in terms of P and HMs. The work here can provide theoretical references for the potential utilization of P from SS to mitigate the foreseeable shortage of P rocks.
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Affiliation(s)
- Xiaoyuan Zheng
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China; Shanghai Key Laboratory of Heat Transfer and Multiphase Flow in Power Engineering, Shanghai, 200093, China
| | - Zhi Ying
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - Yuheng Feng
- Thermal and Environment Engineering Institute, School of Mechanical Engineering, Tongji University, Shanghai, 200092, China.
| | - Bo Wang
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - Binlin Dou
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
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Nimita Jebaranjitham J, Selvan Christyraj JD, Prasannan A, Rajagopalan K, Chelladurai KS, Gnanaraja JKJS. Current scenario of solid waste management techniques and challenges in Covid-19 - A review. Heliyon 2022; 8:e09855. [PMID: 35800245 PMCID: PMC9249431 DOI: 10.1016/j.heliyon.2022.e09855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 03/15/2022] [Accepted: 06/28/2022] [Indexed: 12/09/2022] Open
Abstract
Annually, world generates 2.01 billion tonnes of solid wastes and it is expected to generate 2.2 billion tonnes of solid waste by 2025. Globally double the amount of waste generation was anticipated by 2050, hence an urgent action is required for this intricate problem in adopting better management techniques and recycling strategies. Unfortunately, poor management of wastes causes vulnerable effects to the society in terms of health. Waste management is the key infrastructure to be developed in society, but so far it is not recognized as much in many developing countries. Significant innovations and improvements are made in the last few decades globally, but still 2 to 3 billion people around the world lack access to waste collection services. The aim of this present study is to give an overview of different types of waste techniques that are effectively followed by different countries and the action plans need to follow. This review focuses on the global current scenario of waste generation, and its management methods with relevant literatures providing the upgrades in the phases of waste management services like collection and transport, various techniques adopted for waste management, policies and legislation, countries investment in waste management process and the impact of solid waste management during Covid-19. Collectively we conclude that Asian countries need to allot more fund for handling solid waste. Also with the available waste management technique, it is not possible to achieve zero waste. Therefore, more new techniques are needed to be adapted.
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Liu Q, Huang Q, Zhao Y, Liu Y, Wang Q, Khan MA, Che X, Li X, Bai Y, Su X, Lin L, Zhao Y, Chen Y, Wang J. Dissolved organic matter (DOM) was detected in MSWI plant: An investigation of DOM and potential toxic elements variation in the bottom ash and fly ash. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 828:154339. [PMID: 35257758 DOI: 10.1016/j.scitotenv.2022.154339] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 02/22/2022] [Accepted: 03/02/2022] [Indexed: 06/14/2023]
Abstract
The content of dissolved organic matter (DOM) and potentially toxic elements (PTEs) were investigated in the bottom ash (BA) and fly ash (FA) of different sections of the municipal solid waste incineration (MSWI) plant. BA and FA were collected from the dry (BA1-BA2), burn (BA3-BA4), and burn-out (BA5) sections of the grate incinerator; FA was collected after denitration (DNFA), and from the deacidification tower (FA1) and bag-type dust remover (FA2), respectively. The DOM concentration in BA was higher than that in FA, the highest concentration was in BA3 (556.18 mg/kg), while the lowest concentration was in DNFA (17.53 mg/kg). DOM in BA was mainly composed of protein-like, fulvic-like, tryptophan-like, and humic-like substances, of which humic-like substances accounted for more than 40%. DOM in FA consisted of tryptophan-like and humic-like substances, of which humic-like substances accounted for more than 80%. DOM still existed in BA which may be related to the incomplete combustion, and the influence of microbes, while DOM was increased in FA1, which might be due to the addition of lime slurry. PTEs were analyzed by the Tessier extraction method, Fe-Mn hydroxide-bound fraction of PTEs increased in FA1 in which DOM concentration (137.22 mg/kg) was 7.83 times that in DNFA. The increase of DOM may lead to a higher risk of PTEs in FA. FTIR results indicated that DOM can bond to PTEs in BA and FA. The contents of humus-like substances in DOM were positively correlated with the effective fraction of As, Cu, Pb, Cr, and Cd. This paper investigated the risk of DOM existing in BA and FA in MSWI plant, which can provide a new perspective on how to deal with BA and FA, and reduce their environmental risks.
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Affiliation(s)
- Quan Liu
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Haikou 570228, China; College of Ecology and Environment, Hainan University, Haikou, Hainan 570228, China; Center for Eco-Environmental Restoration Engineering of Hainan Province, Haikou 570228, China; State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China; Key Laboratory for Environmental Toxicology of Haikou, Hainan University, Haikou, Hainan 570228, China
| | - Qing Huang
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Haikou 570228, China; College of Ecology and Environment, Hainan University, Haikou, Hainan 570228, China; Center for Eco-Environmental Restoration Engineering of Hainan Province, Haikou 570228, China; State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China; Key Laboratory for Environmental Toxicology of Haikou, Hainan University, Haikou, Hainan 570228, China.
| | - Youcai Zhao
- The State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| | - Yin Liu
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Haikou 570228, China; College of Ecology and Environment, Hainan University, Haikou, Hainan 570228, China; Center for Eco-Environmental Restoration Engineering of Hainan Province, Haikou 570228, China; State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China; Key Laboratory for Environmental Toxicology of Haikou, Hainan University, Haikou, Hainan 570228, China
| | - Qingqing Wang
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Haikou 570228, China; College of Ecology and Environment, Hainan University, Haikou, Hainan 570228, China; Center for Eco-Environmental Restoration Engineering of Hainan Province, Haikou 570228, China; State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China; Key Laboratory for Environmental Toxicology of Haikou, Hainan University, Haikou, Hainan 570228, China
| | - Muhammad Amjad Khan
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Haikou 570228, China; College of Ecology and Environment, Hainan University, Haikou, Hainan 570228, China; Center for Eco-Environmental Restoration Engineering of Hainan Province, Haikou 570228, China; State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China; Key Laboratory for Environmental Toxicology of Haikou, Hainan University, Haikou, Hainan 570228, China
| | - Xuyang Che
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Haikou 570228, China; College of Ecology and Environment, Hainan University, Haikou, Hainan 570228, China; Center for Eco-Environmental Restoration Engineering of Hainan Province, Haikou 570228, China; State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China
| | - Xiaohui Li
- Hainan Inspection and Detection Center for Modern Agriculture, Haikou, Hainan 570100, China
| | - Yang Bai
- College of Ecology and Environment, Hainan University, Haikou, Hainan 570228, China; College of Management and Economics, Tianjin University, Tianjin 300072, China
| | - Xuesong Su
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Haikou 570228, China; College of Ecology and Environment, Hainan University, Haikou, Hainan 570228, China; Center for Eco-Environmental Restoration Engineering of Hainan Province, Haikou 570228, China; State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China; Key Laboratory for Environmental Toxicology of Haikou, Hainan University, Haikou, Hainan 570228, China
| | - Linyi Lin
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Haikou 570228, China; College of Ecology and Environment, Hainan University, Haikou, Hainan 570228, China; Center for Eco-Environmental Restoration Engineering of Hainan Province, Haikou 570228, China; State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China; Key Laboratory for Environmental Toxicology of Haikou, Hainan University, Haikou, Hainan 570228, China
| | - Yang Zhao
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Haikou 570228, China; College of Ecology and Environment, Hainan University, Haikou, Hainan 570228, China; Center for Eco-Environmental Restoration Engineering of Hainan Province, Haikou 570228, China; State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China; Key Laboratory for Environmental Toxicology of Haikou, Hainan University, Haikou, Hainan 570228, China
| | - Ying Chen
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Haikou 570228, China; College of Ecology and Environment, Hainan University, Haikou, Hainan 570228, China; Center for Eco-Environmental Restoration Engineering of Hainan Province, Haikou 570228, China; State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China; Key Laboratory for Environmental Toxicology of Haikou, Hainan University, Haikou, Hainan 570228, China
| | - Junfeng Wang
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Haikou 570228, China; College of Ecology and Environment, Hainan University, Haikou, Hainan 570228, China; Center for Eco-Environmental Restoration Engineering of Hainan Province, Haikou 570228, China; State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China
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Chang H, Zhao Y, Zhao S, Damgaard A, Christensen TH. Review of inventory data for the thermal treatment of sewage sludge. WASTE MANAGEMENT (NEW YORK, N.Y.) 2022; 146:106-118. [PMID: 35588648 DOI: 10.1016/j.wasman.2022.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 04/22/2022] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Abstract
The thermal treatment of sewage sludge has gained much interest in recent years, as exemplified by the 269 papers found in the scientific literature for the period 2010-2021. We identified 140 datasets in 57 papers presenting inventory data related to mass flows, energy and emissions for the incineration, gasification and pyrolysis of sewage sludge. Sewage sludge incineration (excess oxygen, 850-950 ℃) is an established technology; however, data on flue gas cleaning and air emissions are scarce. The recovery of energy is close to the amount of energy used for incinerating dried sludge (0.2 kWh/kg TS), while dewatered sludge incineration uses more energy (1-2 kWh/kg TS) than what can be recovered. Sewage sludge gasification (limited oxygen, 650-950 ℃) is an experimental technology with four outputs (kg/kg sludge TS): char 0.43, tar 0.02, fly ash 0.06 and syngas 0.53. The data vary significantly in this regard, suggesting than many factors affect the performance of the gasification process. Sewage sludge pyrolysis (no oxygen, 400-800 ℃) is an experimental technology with five outputs (kg/kg sludge TS): char 0.53, tar 0.21, water < 0.05, fly ash set to zero and syngas 0.21. The values are somewhat different for digested sludge. Energy consumption for the pyrolysis of sewage sludge cannot be estimated from the literature. The current literature provides useful data on the main flows of thermal technologies, although large variations are in evidence. However, data are limited on energy consumption and recovery in general, and they are scarce on direct emissions to the air from incineration.
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Affiliation(s)
- Huimin Chang
- School of Environment, Beijing Normal University, Beijing 100875, China
| | - Yan Zhao
- School of Environment, Beijing Normal University, Beijing 100875, China.
| | - Silan Zhao
- School of Environment, Beijing Normal University, Beijing 100875, China
| | - Anders Damgaard
- Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby 2800, Denmark
| | - Thomas H Christensen
- Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby 2800, Denmark
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Boniardi G, Turolla A, Fiameni L, Gelmi E, Bontempi E, Canziani R. Phosphorus recovery from a pilot-scale grate furnace: influencing factors beyond wet chemical leaching conditions. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2022; 85:2525-2538. [PMID: 35576251 DOI: 10.2166/wst.2022.132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Phosphorus is a non-renewable resource going to be exhausted in the future. Sewage sludge ash is a promising secondary raw material due to its high phosphorus content. In this work, the distribution of 19 elements in bottom and cyclone ashes from pilot-scale grate furnace have been monitored to determine the suitability for the phosphorus acid extraction. Moreover, the influence of some parameters beyond wet chemical leaching conditions were investigated. Experimental results showed that bottom ash presented lower contamination in comparison to cyclone ash and low co-dissolution of heavy metals (especially Cr, Pb and Ni), while high phosphorus extraction efficiencies (76-86%) were achieved. High Al content in the bottom ash (9.4%) negatively affected the phosphorus extraction efficiency as well as loss on ignition, while the particle size reduction was necessary for ensuring a suitable contact surface. The typology of precipitating agents did not strongly affect the phosphorus precipitation, while pH was the key parameter. At pH 3.5-5, phosphorus precipitation efficiencies higher than 90% were achieved, with a mean phosphorus content in the recovered material equal to 16-17%, comparable to commercial fertilizers. Instead, the co-precipitation of Fe and Al had a detrimental effect on the recovered material, indicating the need for additional treatments.
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Affiliation(s)
- G Boniardi
- Department of Civil and Environmental Engineering (DICA), Politecnico di Milano, Piazza Leonardo da Vinci 21, 20133, Milano, Italy E-mail:
| | - A Turolla
- Department of Civil and Environmental Engineering (DICA), Politecnico di Milano, Piazza Leonardo da Vinci 21, 20133, Milano, Italy E-mail:
| | - L Fiameni
- INSTM and University of Brescia, Via Branze 38, 25123, Brescia, Italy
| | - E Gelmi
- Department of Civil and Environmental Engineering (DICA), Politecnico di Milano, Piazza Leonardo da Vinci 21, 20133, Milano, Italy E-mail:
| | - E Bontempi
- INSTM and University of Brescia, Via Branze 38, 25123, Brescia, Italy
| | - R Canziani
- Department of Civil and Environmental Engineering (DICA), Politecnico di Milano, Piazza Leonardo da Vinci 21, 20133, Milano, Italy E-mail:
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Cheng Y, Asaoka Y, Hachiya Y, Moriuchi N, Shiota K, Oshita K, Takaoka M. Mercury emission profile for the torrefaction of sewage sludge at a full-scale plant and application of polymer sorbent. JOURNAL OF HAZARDOUS MATERIALS 2022; 423:127186. [PMID: 34844339 DOI: 10.1016/j.jhazmat.2021.127186] [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: 06/13/2021] [Revised: 08/19/2021] [Accepted: 09/07/2021] [Indexed: 06/13/2023]
Abstract
We evaluated mercury (Hg) behavior in a full-scale sewage sludge torrefaction plant with a capacity of 150 wet tons/day, which operates under a nitrogen atmosphere at a temperature range of 250-350 °C. Thermodynamic calculations and monitoring results show that elemental Hg (Hg0) was the dominant species in both the pyrolysis gas during the torrefaction stage and in the flue gas from downstream air pollution control devices. A wet scrubber (WS) effectively removed oxidized Hg from the flue gas and moved Hg to wastewater, and an electrostatic precipitator (ESP) removed significant particulate-bound Hg but showed a limited capacity for overall Hg removal. Hg bound to total suspended solids had a much higher concentration than that of dissolved Hg in wastewater. Total suspended solid removal from wastewater is therefore recommended to reduce Hg discharge. Existing air pollution control devices, which consist of a cyclone, WS, and ESP, are not sufficient for Hg removal due to the poor Hg0 removal performance of the WS and ESP; a further Hg0 removal unit is necessary. A commercial packed tower with sorbent polymer catalyst composite material was effective in removing Hg (83.3%) during sludge torrefaction.
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Affiliation(s)
- Yingchao Cheng
- Department of Environmental Engineering, Ce School of Engineering, Kyoto University, Katsura, Nisikyo-ku, Kyoto 615-8540, Japan; Global Resource Sustainability Research Section, Material Cycles Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506, Japan
| | - Yuki Asaoka
- Tsukishima Kikai Co., Ltd. Solution, Technology Department, 3-5-1, Harumi, Chuo-ku, Tokyo 104-0053, Japan
| | - Yoshiyuki Hachiya
- Tsukishima Kikai Co., Ltd. Solution, Technology Department, 3-5-1, Harumi, Chuo-ku, Tokyo 104-0053, Japan
| | - Naoki Moriuchi
- W. L. Gore & Associates, G.K.-14 F, W Building, 1-8-15 Konan, Minato-ku, Tokyo 108-0075, Japan
| | - Kenji Shiota
- Department of Environmental Engineering, Ce School of Engineering, Kyoto University, Katsura, Nisikyo-ku, Kyoto 615-8540, Japan
| | - Kazuyuki Oshita
- Department of Environmental Engineering, Ce School of Engineering, Kyoto University, Katsura, Nisikyo-ku, Kyoto 615-8540, Japan
| | - Masaki Takaoka
- Department of Environmental Engineering, Ce School of Engineering, Kyoto University, Katsura, Nisikyo-ku, Kyoto 615-8540, Japan.
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Influence of Temperature on Characteristics of Particulate Matter and Ecological Risk Assessment of Heavy Metals during Sewage Sludge Pyrolysis. MATERIALS 2021; 14:ma14195838. [PMID: 34640235 PMCID: PMC8510102 DOI: 10.3390/ma14195838] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 09/28/2021] [Accepted: 09/29/2021] [Indexed: 11/22/2022]
Abstract
The formation process of Particulate Matter (PM) during sludge pyrolysis at different temperatures (300–700 °C) and the ecological risks of heavy metals were studied. The results showed that the particulate matter is mainly condensed on the quartz film in a carbon-based organic matter when the pyrolysis temperature was between 200–500 °C in a volatilization process. Inorganic particles was found in the particulate matter when the temperature was raised to 500–700 °C in a decomposition stage. Heavy metals were enriched in particulate matter with increase in pyrolysis temperature. When the temperature reached 700 °C, the concentration of Pb and Cd in the particulate matter significantly increased. The ecological risk assessment showed that heavy metals in the sewage sludge had considerable ecological toxicity. When the pyrolysis temperature reached 700 °C, the ecological toxicity of those heavy metals enriched in the particulate matter decreased considerably.
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Zhang Z, Ju R, Zhou H, Chen H. Migration characteristics of heavy metals during sludge pyrolysis. WASTE MANAGEMENT (NEW YORK, N.Y.) 2021; 120:25-32. [PMID: 33279824 DOI: 10.1016/j.wasman.2020.11.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 10/06/2020] [Accepted: 11/18/2020] [Indexed: 06/12/2023]
Abstract
A comprehensive study was conducted to investigate the pyrolysis characteristics of municipal sludge, and the activation energy of sludge pyrolysis was determined using the Model-free method. The detailed migration characteristics of heavy metals in the pyrolysis products were also investigated at different pyrolysis temperatures (250-850 °C). The results demonstrate that sludge pyrolysis is a multi-step process; the activation energy of pyrolysis increased with the pyrolysis conversion rate, and the average activation energy was calculated as 79.59 kJ mol-1. As the pyrolysis temperature increased, the char yield decreased, the tar yield increased then decreased, and the gas yield increased. At 850 °C, the thermal volatilities of heavy metals followed the sequence Cu < Cr < Ni < Mn < Pb < As < Zn < Cd = Hg. In addition, Cu, Cr, and Ni were seldom involved in migration during pyrolysis while As, Cd, and Hg readily migrated even at low pyrolysis temperatures. The results provide a theoretical basis for sludge pyrolysis technologies and heavy metals migration control.
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Affiliation(s)
- Zhiyuan Zhang
- School of Energy and Architectural Environment Engineering, Henan University of Urban Construction, Pingdingshan 467036, China.
| | - Rui Ju
- School of Energy and Architectural Environment Engineering, Henan University of Urban Construction, Pingdingshan 467036, China.
| | - Hengtao Zhou
- School of Energy and Architectural Environment Engineering, Henan University of Urban Construction, Pingdingshan 467036, China.
| | - Hongwei Chen
- Key Laboratory of Condition Monitoring and Control for Power Plant Equipment, Ministry of Education, North China Electric Power University, Baoding 071003, China
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Directions and Challenges in the Management of Municipal Sewage Sludge in Poland in the Context of the Circular Economy. SUSTAINABILITY 2020. [DOI: 10.3390/su12093686] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Landfilling was the main method of sewage sludge disposal in Poland for decades. After Poland’s accession to the European Union (EU), many investments have been made into providing better access to tap water as well as to collect and treat municipal sewage. However, sewage sludge treatment has not been treated as an integral part of the implementation of wastewater management obligations. Stricter European Union regulations regarding the management of municipal sewage sludge (MSS) pose new challenges for Poland. The aim of this study was to analyze changes in the direction of the final management of municipal sewage sludge in Poland based on the analysis of strategic documents, regulations, literature, and available statistical data. The aim of the analysis was to search for directions to modify how sewage sludge is managed, given the approach promoted by the circular economy concept. The results prove that investments in wastewater treatment plants according to the EU sewage directive are not applied to the development of infrastructure that would enable the disposal of sewage sludge, which, for many years, has been stored (landfilling) or used directly in agriculture and ground reclamation. The introduction of stricter regulations in the area of sewage sludge usage and better wastewater treatment have increased the level of difficulties concerning sewage sludge management. Poland faces the challenge of defining sewage sludge management directions. The circular economy concept offers an approach that can be the basis for the creation of a new sewage sludge management strategy for Poland. The concept allows the combined goals of sewage sludge disposal and of energy and nutrients recovery to be achieved.
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