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Xu G, Yang X, Yu F, Mei J, Liu M, Li M, Zhu T, Fang B. Impact of several sludge dewatering conditioners on municipal sludge pyrolysis properties, kinetics, by-products, and environmental risk assessment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 951:175653. [PMID: 39181267 DOI: 10.1016/j.scitotenv.2024.175653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2024] [Revised: 08/03/2024] [Accepted: 08/18/2024] [Indexed: 08/27/2024]
Abstract
The pyrolysis characteristics of four different types of conditioned sludge were ascertained, and PAM, CaO, K2FeO4, and K2FeO4-CaO-PAM (KCP) conditioners were employed as sludge dewatering conditioners. The sludge pyrolysis reaction's activation energy (E) dropped with the addition of four conditioners. CaO, PAM, KCP, and K2FeO4 were the sequences of E needed for the pyrolysis of four different types of conditioned sludge. The addition of K2FeO4, CaO, and KCP resulted in an increase in the yields of H2 and CO. Except for the K2FeO4 conditioning sludge carbon, the pyrolytic carbon of the other three groups of samples showed an increase in S contents, while the pyrolytic carbon of the four groups of samples treated with conditioners clearly showed lower C and N contents compared to the raw sludge carbon. Protein-N made up the majority of N in sludge pyrolytic carbon. After adding conditioner, the level of organic sulfur decreased. Organic sulfur could then be broken down by K2FeO4 and CaO. The four conditioners efficiently mitigated the ecological and environmental risks posed by heavy metals. Alkynes were the most abundant result in pyrolytic volatiles of sludge pyrolysis; the other products included acids, alcohols, lipids, furans, ketones, phenols, hydrocarbons, N-components, and so on. All samples' acids, alcohols, and ketones from pyrolysis were decreased once the conditioner was added. The acid reduction rate reached 66.7 %, and the alkynes clearly increased during the KCP conditioned sludge's pyrolysis. The sulfur level of the bio-oil was decreased by all four conditioners. Everything mentioned above indicated that the KCP aided in the subsequent pyrolysis of the sludge, leading to the production of an advantageous pyrolysis bio-oil.
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Affiliation(s)
- Guiying Xu
- College of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China.
| | - Xiaoxuan Yang
- College of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Feihong Yu
- College of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Jiangnan Mei
- College of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Mingming Liu
- College of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Mingsong Li
- College of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Teng Zhu
- College of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Baizeng Fang
- Department of Chemical & Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC V6P 1Z3, Canada
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Cheng S, Chen L, Wang S, Yao K, Tian H. Insights into the Synergistic Effect and Inhibition Mechanism of Composite Conditioner on Sulfur-Containing Gases during Sewage Sludge Pyrolysis. Molecules 2024; 29:4110. [PMID: 39274958 PMCID: PMC11396920 DOI: 10.3390/molecules29174110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2024] [Revised: 08/26/2024] [Accepted: 08/26/2024] [Indexed: 09/16/2024] Open
Abstract
Sewage sludge odorous gas release is a key barrier to resource utilization, and conditioners can mitigate the release of sulfur-containing gases. The gas release characteristics and sulfur compound distribution in pyrolysis products under both single and composite conditioning strategies of CaO, Fe2O3, and FeCl3 were investigated. This study focused on the inhibition mechanisms of these conditioners on sulfur-containing gas emissions and compared the theoretical and experimental sulfur content in the products to evaluate the potential synergistic effects of the composite conditioners. The findings indicated that at 650 °C, CaO, Fe2O3, and FeCl3 inhibited H2S release by 35.8%, 23.2%, and 9.1%, respectively. Notably, the composite of CaO with FeCl3 at temperatures ranging from 350 to 450 °C and the combination of Fe2O3 with FeCl3 at 650 °C were found to exert synergistic suppression on H2S emissions. The strongly alkaline CaO inhibited the metathesis reaction between HCl, a decomposition product of FeCl3, and the sulfur-containing compounds within the sewage sludge, thereby exerting a synergistic suppression on the emission of H2S. Conversely, at temperatures exceeding 550 °C, the formation of Ca-Fe compounds, such as FeCa2O4, appeared to diminish the sulfur-fixing capacity of the conditioners, resulting in increased H2S emissions. For instance, the combination of CaO and FeCl3 at 450 °C was found to synergistically reduce H2S emissions by 56.3%, while the combination of CaO and Fe2O3 at 650 °C synergistically enhances the release of H2S by 23.6%. The insights gained from this study are instrumental in optimizing the pyrolysis of sewage sludge, aiming to minimize its environmental footprint and enhance the efficiency of resource recovery.
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Affiliation(s)
- Shan Cheng
- School of Energy and Power Engineering, Changsha University of Science and Technology, Changsha 410114, China
| | - Lianghui Chen
- School of Energy and Power Engineering, Changsha University of Science and Technology, Changsha 410114, China
| | - Shaoshuo Wang
- School of Energy and Power Engineering, Changsha University of Science and Technology, Changsha 410114, China
| | - Kehui Yao
- School of Energy and Power Engineering, Changsha University of Science and Technology, Changsha 410114, China
| | - Hong Tian
- School of Energy and Power Engineering, Changsha University of Science and Technology, Changsha 410114, China
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Hou J, Hong C, Ling W, Hu J, Feng W, Xing Y, Wang Y, Zhao C, Feng L. Research progress in improving sludge dewaterability: sludge characteristics, chemical conditioning and influencing factors. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 351:119863. [PMID: 38141343 DOI: 10.1016/j.jenvman.2023.119863] [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: 09/11/2023] [Revised: 11/29/2023] [Accepted: 12/12/2023] [Indexed: 12/25/2023]
Abstract
Sludge from wastewater treatment processes with high water content and large volume has become an inevitable issue in environmental management. Due to the challenging dewatering properties of sludge, current mechanical dewatering methods are no longer sufficient to meet the escalating water content standards of sludge. This paper summarizes the characteristics of various sludge and raises reasons for the their dewaterability differences. Affected by extracellular polymeric substances, biological sludge is hydrophilic and negatively charged, which limits the dewatering degree. The rheological properties, flocs, ionic composition, and solid phase concentration of the sludge also influence the dewatering to some extent. For these factors, the chemical conditioning measures with simple operation and excellent effect improve its dewaterability, which mainly include flocculation/coagulation, acid/alkali treatment, advanced oxidation, surfactant treatment and combined treatment. There is a growing necessity to explore the development of new chemical conditioning agents, even though traditional agents continue to remain widely used. However, the development of these new agents should prioritize finding a balance between various factors such as efficiency, effectiveness, ease of operation, environmental safety, and cost-effectiveness. Electrochemical dewatering enhances solid-liquid separation, and its coupling with chemical conditioning is also an excellent means to further reduce water content. In addition, the improvement of press filter is an effective way, which is influenced by pressure, processing time, sludge cake thickness and pore structure, filter media etc. In general, it is essential to develop new conditioning agents and enhance mechanical filtration press technology based on a thorough understanding of various sludge properties. Concurrently, an in-depth study of the principles of mechanical pressure filtration will contribute to establishing a theoretical foundation for effective deep sludge dewatering and propel further advancements in this field.
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Affiliation(s)
- Jiachen Hou
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Chen Hong
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Wei Ling
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Jiashuo Hu
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Weibo Feng
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Yi Xing
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing, 100083, China
| | - Yijie Wang
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Chengwang Zhao
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Lihui Feng
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
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Wang Z, Huang J, Wang J, Hu Z, Xu M, Qiao Y. Co-hydrothermal carbonization of sludge and food waste for hydrochar valorization: Effect of mutual interaction on sulfur transformation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 905:167318. [PMID: 37742985 DOI: 10.1016/j.scitotenv.2023.167318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 09/02/2023] [Accepted: 09/21/2023] [Indexed: 09/26/2023]
Abstract
Co-hydrothermal carbonization of sludge and food waste is a promising method for hydrochar valorization. The sulfur content and form of hydrochar are the key parameters that determine its further utilization. However, the effect of the chemical composition of food waste on sulfur redistribution remains unknown. Herein, the sulfur transformation behavior during the co-hydrothermal carbonization of sludge and model compounds (cellulose, starch, xylan, and palmitic acid) of food waste was investigated, with focus on the detailed reaction pathways from inorganic-S/organic-S media in aqueous to hydrochar. The added model compounds, particularly the starch and xylan, increased the sulfur retention ratio from 41.0 to 44.7- 49.2 % in hydrochar. Among them, starch and xylan can react with aliphatic-S in aqueous via cyclization and oxidization to form the thiophene-S/aromatic-S and sulfone-S and can react with SO42--S to form sulfone-S via sulfonate reaction. These formed organic-S can polymerize with hydrolyzed intermediates (i.e., 5 hydroxymethyl-furfural, glucose, and xylose) from model compounds to transform into hydrochar. Cellulose enhanced the formation of sulfone-S in hydrochar via the reactions between the water-insoluble partial hydrolysate and SO42- in the aqueous. Additionally, palmitic acid hydrolysate provided an acidic environment that facilitated the polymerization of thiophene-S/aromatic-S from aqueous to hydrochar. Generally, the chemical composition of food waste largely affects the redistribution behavior of sulfur during co-hydrothermal carbonization, and this occurs primarily due to the differences in the hydrolysate and degree of hydrolysis for various model compounds. The results can provide guidance for preparing sludge-based hydrochar possessing different sulfur content and species, that can be used as clean fuel or carbon material.
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Affiliation(s)
- Zhenqi Wang
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Jingchun Huang
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China.
| | - Junwen Wang
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zhen Hu
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Minghou Xu
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yu Qiao
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China
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Dong Y, Wang F, Ye Z, He F, Qin L, Lv G. Acid gas emission and ash fusion characteristics of multi-component leather solid waste incineration in bubbling fluidized bed. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 335:122249. [PMID: 37487872 DOI: 10.1016/j.envpol.2023.122249] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 06/15/2023] [Accepted: 07/21/2023] [Indexed: 07/26/2023]
Abstract
The tanning sludge (TS) and other tanning solid wastes are produced in significant quantities by the leather industry. To evaluate the combustion properties, acid gaseous pollutant conversion, and ash management, co-firing of TS with various wastes was investigated in a bubbling fluidized bed. TG-FTIR test indicated that tanning solid wastes had superior combustion properties and include more gaseous pollutants than TS. The leather mixed solid waste (LMSW) formed by mixing had better fuel characteristics than TS. The conversion rates of SO2 and HCl of LMSW incineration were 67% and 40%, respectively. The co-combustion of TS and solid wastes reduces the conversion rate of acid gas. Increasing the proportion of high-inorganic chlorine raw material could further reduce the conversion rate and increase the ash fusion temperature appropriately. Because ash and slag were primarily composed of Ca and Fe elements, the addition of calcium carbonate (CaCO3) can increase ash melting point while reducing acid gas emissions. When CaCO3 was added at a calcium to sulfur (Ca/S) ratio of 2, the acid gas emission was reduced by more than 80% and the softening temperature was raised by 90 °C. When Ca/S is greater than 2, the economics of adding CaCO3 decreased.
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Affiliation(s)
- Yuhang Dong
- State Key Laboratory of Clean Energy Utilization, Institute of Thermal Power Engineering of Zhejiang University, Hangzhou, 310027, Zhejiang, China
| | - Fei Wang
- State Key Laboratory of Clean Energy Utilization, Institute of Thermal Power Engineering of Zhejiang University, Hangzhou, 310027, Zhejiang, China.
| | - Zhirong Ye
- State Key Laboratory of Clean Energy Utilization, Institute of Thermal Power Engineering of Zhejiang University, Hangzhou, 310027, Zhejiang, China
| | - Fengyu He
- State Key Laboratory of Clean Energy Utilization, Institute of Thermal Power Engineering of Zhejiang University, Hangzhou, 310027, Zhejiang, China
| | - Lishan Qin
- State Key Laboratory of Clean Energy Utilization, Institute of Thermal Power Engineering of Zhejiang University, Hangzhou, 310027, Zhejiang, China
| | - Guojun Lv
- State Key Laboratory of Clean Energy Utilization, Institute of Thermal Power Engineering of Zhejiang University, Hangzhou, 310027, Zhejiang, China
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Lu M, Xue Y, Zhao H, Zhang X, Wang T. Effect of electromagnetic induction drying on the drying-incineration process of dyeing sludge: focus on migration and conversion of sulfur. WASTE MANAGEMENT (NEW YORK, N.Y.) 2023; 171:522-531. [PMID: 37806160 DOI: 10.1016/j.wasman.2023.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 09/15/2023] [Accepted: 10/03/2023] [Indexed: 10/10/2023]
Abstract
Secondary sulfur pollution in dyeing sludge (DS) during drying and incineration is a major environmental problem necessitating in-situ control. To robustly immobilise sulfur during drying-incineration, the authors introduce an electromagnetic induction (EMI) drying method and reveal the corresponding migration and conversion of sulfur in DS. The EMI-drying efficiency reached 10.69%/min, five times that of thermal drying. EMI drying increases the relative sulfoxide ratio from that of thermal drying. In a sludge-sulfur model, the proposed treatment promoted the oxidation and decomposition of organic sulfur without noticeably affecting the inorganic sulfur. The selective oxidation process during EMI drying promotes sulfur stabilisation in dried DS, decreasing the performance and stability of DS combustion. The sulfur-containing pollutants released during the incineration of DS mainly contain H2S, followed by CH3SH and SO2. EMI drying increases the outputs of SO2 and CH3SH but decreases the outputs H2S and total sulfur compared with the outputs of thermal drying. Under the sulfur-model conditions, EMI promoted the conversion of inorganic sulfur to sulfur-containing gases (especially H2S) during incineration. In contrast, the sulfur stabilised by partial oxidation of organic sulfur in the EMI-dried DS was not easily converted to gaseous sulfur during subsequent combustion. Overall, EMI inhibits the release of sulfur during the combined drying-incineration process of DS.
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Affiliation(s)
- Mengxin Lu
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
| | - Yongjie Xue
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
| | - Hui Zhao
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
| | - Xiaoshan Zhang
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
| | - Teng Wang
- School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, China; Engineering Research Centre for Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan Textile University, Wuhan 430073, China.
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Zhang Q, Chen Y, Xue Y, Chen S, Liu J, Mei M, Li J, Ren L, Wang T. Study on the effect of biomass on sulfur release behavior from dyeing sludge incineration: Focusing on in-situ sulfur fixation mechanism based on model compounds. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 875:162544. [PMID: 36871733 DOI: 10.1016/j.scitotenv.2023.162544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/21/2023] [Accepted: 02/25/2023] [Indexed: 06/18/2023]
Abstract
Although incineration is a recommended disposal strategy for dyeing sludge (DS), sulfurous gases problem is severe. Wood sawdust (WS) and rice husk (RH) are eco-friendly and CO2-neutral additives to relieve sulfur emission from DS incineration. However, the interaction between organic sulfur and biomass is uninterpreted. This study explores the effect of WS and RH on the combustion behavior and sulfur evolution from organic sulfur model compound combustion via thermogravimetry (TG) with mass spectrometry (MS). Results indicated that the sulfone and mercaptan combustion activities in DS were more drastic than in other forms. WS and RH additives generally deteriorated the combustibility and burnout performance of model compounds. The combustion of mercaptan and sulfone in DS contributed to most gaseous sulfur pollutants, where CH3SH and SO2 were the predominant forms. WS and RH minimized the sulfur release from mercaptan and sulfone incineration, whose in-situ retention ratios reached 20.14 % and 40.57 %. The retention mechanism to sulfur could be divided into: (1) Diffusion stage: the closed structure of biomass residue restrained sulfurous gases from escaping. (2) Chemical reaction stage: multiple sulfation occurred and inhibited sulfur release. Ca/K sulfate and compound sulfates were predisposed and thermostable sulfur-fixing products for the mercaptan-WS and sulfone-RH co-combustion systems.
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Affiliation(s)
- Qinyuan Zhang
- School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, China
| | - Yuchi Chen
- Center for Water and Ecology School of Environment, Tsinghua University, 100084 Beijing, China
| | - Yongjie Xue
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China
| | - Si Chen
- School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, China; Engineering Research Centre for Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan Textile University, Wuhan 430073, China
| | - Jingxin Liu
- School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, China; Engineering Research Centre for Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan Textile University, Wuhan 430073, China
| | - Meng Mei
- School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, China; Engineering Research Centre for Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan Textile University, Wuhan 430073, China
| | - Jinping Li
- School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, China; Engineering Research Centre for Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan Textile University, Wuhan 430073, China
| | - Lu Ren
- School of Civil Engineering, Suzhou University of Science and Technology, 215009 Suzhou, China
| | - Teng Wang
- School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, China; Engineering Research Centre for Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan Textile University, Wuhan 430073, China.
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