Pub Date : 2025-06-19DOI: 10.1007/s42768-025-00239-0
Juan Qiu, Xuanhao Guo, Guanjie Wang, Minghui Tang, Yaqi Peng, Shengyong Lu, Jianhua Yan
The removal of polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) and dust from municipal solid waste incineration flue gas within a single device can improve operational efficiency and reduce costs. In this study, a catalytic filter was developed using ultrasonic immersion and polytetrafluoroethylene (PTFE) membrane fixation, combining a blank PTFE and VOx/TiO2 catalyst. Chlorobenzene (CB) and furan were selected as model molecules for PCDD/Fs. A series of VOx/TiO2 catalysts were synthesized through a mechanochemical method, with different types and ratios of components tested. Among these catalysts, the VWMoTi catalyst demonstrated the highest CB removal efficiency (RE), reaching over 85% at temperatures below 200 °C. The VWMoTi catalyst was impregnated into a PTFE filter for the catalytic combustion of CB and furan. The process parameters, including the catalyst loading and catalyst particle size, were analyzed. The physicochemical properties of the catalytic filter were extensively characterized. The catalytic activity of CB, furan, and dust removal performance of the catalytic filters was investigated. At 240 °C, the RE values of CB and furan were 70.82% and 100%, respectively, whereas the RE of dust reached 99.99%.
{"title":"Novel development of VWMoTi@PTFE catalytic filter for simultaneous elimination of chlorobenzene and furan at low temperatures","authors":"Juan Qiu, Xuanhao Guo, Guanjie Wang, Minghui Tang, Yaqi Peng, Shengyong Lu, Jianhua Yan","doi":"10.1007/s42768-025-00239-0","DOIUrl":"10.1007/s42768-025-00239-0","url":null,"abstract":"<div><p>The removal of polychlorinated dibenzo-<i>p</i>-dioxins and dibenzo-furans (PCDD/Fs) and dust from municipal solid waste incineration flue gas within a single device can improve operational efficiency and reduce costs. In this study, a catalytic filter was developed using ultrasonic immersion and polytetrafluoroethylene (PTFE) membrane fixation, combining a blank PTFE and VO<sub><i>x</i></sub>/TiO<sub>2</sub> catalyst. Chlorobenzene (CB) and furan were selected as model molecules for PCDD/Fs. A series of VO<sub><i>x</i></sub>/TiO<sub>2</sub> catalysts were synthesized through a mechanochemical method, with different types and ratios of components tested. Among these catalysts, the VWMoTi catalyst demonstrated the highest CB removal efficiency (RE), reaching over 85% at temperatures below 200 °C. The VWMoTi catalyst was impregnated into a PTFE filter for the catalytic combustion of CB and furan. The process parameters, including the catalyst loading and catalyst particle size, were analyzed. The physicochemical properties of the catalytic filter were extensively characterized. The catalytic activity of CB, furan, and dust removal performance of the catalytic filters was investigated. At 240 °C, the RE values of CB and furan were 70.82% and 100%, respectively, whereas the RE of dust reached 99.99%.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"7 3","pages":"371 - 379"},"PeriodicalIF":0.0,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145078905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-04DOI: 10.1007/s42768-025-00226-5
Babusi Balopi, Mahluli Moyo, Joshua Gorimbo, Xinying Liu
In order to promote the use of biomass as an alternative to fossil fuels, this review aims to survey the literature to identify technologies used to generate electricity from biomass. The main biomass conversion technologies, including combustion, biomass gasification, biomass pyrolysis, co-firing biomass with coal, anaerobic digestion and biomass fermentation, have been successfully used to generate electricity from different types of biomass. As opposed to fossil fuels, using biomass to generate electricity has a lower carbon footprint, which is eco-friendly over fossil fuels. This review introduces mature biomass-to-electricity technologies, compares the maturity of those technologies, identifies challenges that impede the use of the technologies to decentralise electricity supply from national grids, and then provides future perspectives and concluding remarks on the biomass-to-electricity conversion technologies with the potential to eliminate the shortage of electricity in remote settlements. The identified challenges that hinder the implementation of biomass-to-electricity technologies are low biomass collection efficiency, utilization of biomass which competes with low-cost fossil fuels, competition for land used for food production, and poor implementation of policies to encourage implementation of biomass-to-electricity technologies. In addition, the financial challenges can be significant as investment costs to establish advanced technologies for biomass energy systems can be relatively high, and ongoing expenses for regular maintenance and monitoring are also substantial to ensure optimal performance to mitigate environmental issues.
{"title":"Biomass-to-electricity conversion technologies: a review","authors":"Babusi Balopi, Mahluli Moyo, Joshua Gorimbo, Xinying Liu","doi":"10.1007/s42768-025-00226-5","DOIUrl":"10.1007/s42768-025-00226-5","url":null,"abstract":"<div><p>In order to promote the use of biomass as an alternative to fossil fuels, this review aims to survey the literature to identify technologies used to generate electricity from biomass. The main biomass conversion technologies, including combustion, biomass gasification, biomass pyrolysis, co-firing biomass with coal, anaerobic digestion and biomass fermentation, have been successfully used to generate electricity from different types of biomass. As opposed to fossil fuels, using biomass to generate electricity has a lower carbon footprint, which is eco-friendly over fossil fuels. This review introduces mature biomass-to-electricity technologies, compares the maturity of those technologies, identifies challenges that impede the use of the technologies to decentralise electricity supply from national grids, and then provides future perspectives and concluding remarks on the biomass-to-electricity conversion technologies with the potential to eliminate the shortage of electricity in remote settlements. The identified challenges that hinder the implementation of biomass-to-electricity technologies are low biomass collection efficiency, utilization of biomass which competes with low-cost fossil fuels, competition for land used for food production, and poor implementation of policies to encourage implementation of biomass-to-electricity technologies. In addition, the financial challenges can be significant as investment costs to establish advanced technologies for biomass energy systems can be relatively high, and ongoing expenses for regular maintenance and monitoring are also substantial to ensure optimal performance to mitigate environmental issues.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"7 2","pages":"323 - 351"},"PeriodicalIF":0.0,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s42768-025-00226-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145161675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-23DOI: 10.1007/s42768-025-00232-7
Cheng Chen, Yang Xu, Fei Wang
With increasing amounts of sewage sludge (SS) every year, the treatment of sewage SS and sewage sludge ash (SSA) has become an urgent and inevitable issue worldwide. The use of these wastes in building bricks seems to be an alternative solution. The main oxides in SS and SSA are the same as those in clay, such as SiO2 (10.00%–45.00%), CaO (5.00%–15.00%), Al2O3 (10.00%–15.00%) and Fe2O3 (5.00%–15.00%), indicating that these wastes have potential for building bricks. By investigating the various uses of SS, an increase of up to 20.00% in utilization can be achieved. A high incineration temperature enhances the stable performance of SSA, increasing the amount of SSA added to bricks. Moreover, mixing agricultural and industrial wastes, which contain low moisture contents or high silica contents, can improve the thermal insulation performance or mechanical strength of bricks. The performance of additive directionally modified bricks has expanded the use of bricks. The solidification of heavy metals by SS avoids secondary pollution of the environment. Finally, the above innovative studies provide suggestions for future high-value production.
{"title":"Sewage sludge and incineration ash mixed with different materials for manufacturing bricks: a review","authors":"Cheng Chen, Yang Xu, Fei Wang","doi":"10.1007/s42768-025-00232-7","DOIUrl":"10.1007/s42768-025-00232-7","url":null,"abstract":"<div><p>With increasing amounts of sewage sludge (SS) every year, the treatment of sewage SS and sewage sludge ash (SSA) has become an urgent and inevitable issue worldwide. The use of these wastes in building bricks seems to be an alternative solution. The main oxides in SS and SSA are the same as those in clay, such as SiO<sub>2</sub> (10.00%–45.00%), CaO (5.00%–15.00%), Al<sub>2</sub>O<sub>3</sub> (10.00%–15.00%) and Fe<sub>2</sub>O<sub>3</sub> (5.00%–15.00%), indicating that these wastes have potential for building bricks. By investigating the various uses of SS, an increase of up to 20.00% in utilization can be achieved. A high incineration temperature enhances the stable performance of SSA, increasing the amount of SSA added to bricks. Moreover, mixing agricultural and industrial wastes, which contain low moisture contents or high silica contents, can improve the thermal insulation performance or mechanical strength of bricks. The performance of additive directionally modified bricks has expanded the use of bricks. The solidification of heavy metals by SS avoids secondary pollution of the environment. Finally, the above innovative studies provide suggestions for future high-value production.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"7 2","pages":"287 - 301"},"PeriodicalIF":0.0,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145168200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-23DOI: 10.1007/s42768-025-00230-9
Daien Yang, Zhiyuan Zhang, Fushen Zhang
Ecological concrete (EC) has received special attention recently, but its application has been largely limited by the high alkalinity caused by cement. In this study, a novel low alkalinity cementitious material (cementitious material developed from subway tunnel muck, S-CM) was developed from subway tunnel muck (STM). STM was activated by ball milling and the optimal time was 2 h. It was found that the solubilities of Si and Al of STM were enhanced by 1.74 and 2.36 times after mechanical activation. The leaching kinetics of Si and Al could be well described by Avrami model. The activated STM was a reactant in the cementitious system, and the higher Si and Al solubilities led to better gel generation. S-CM-2h exhibited a denser structure with lower porosity (34.88%), higher density (1.67 g/mL) and fewer macropores. The compressive strength of S-CM saw a notable increase from 4.06 to 10.14 MPa as a result of the denser microstructure and enhanced gel generation. Further study indicated that S-CM had much better environmental compatibility than sulphoaluminate cement in EC preparation. EC developed from S-CM had a 13.8% lower alkalinity, better root growth and a 47.5% higher dry weight of plants than EC developed from cement. This study provides a new approach for high value-added recycling of STM.
{"title":"The recycling of subway tunnel muck: a low alkalinity cementitious material for ecological concrete preparation","authors":"Daien Yang, Zhiyuan Zhang, Fushen Zhang","doi":"10.1007/s42768-025-00230-9","DOIUrl":"10.1007/s42768-025-00230-9","url":null,"abstract":"<div><p>Ecological concrete (EC) has received special attention recently, but its application has been largely limited by the high alkalinity caused by cement. In this study, a novel low alkalinity cementitious material (cementitious material developed from subway tunnel muck, S-CM) was developed from subway tunnel muck (STM). STM was activated by ball milling and the optimal time was 2 h. It was found that the solubilities of Si and Al of STM were enhanced by 1.74 and 2.36 times after mechanical activation. The leaching kinetics of Si and Al could be well described by Avrami model. The activated STM was a reactant in the cementitious system, and the higher Si and Al solubilities led to better gel generation. S-CM-2h exhibited a denser structure with lower porosity (34.88%), higher density (1.67 g/mL) and fewer macropores. The compressive strength of S-CM saw a notable increase from 4.06 to 10.14 MPa as a result of the denser microstructure and enhanced gel generation. Further study indicated that S-CM had much better environmental compatibility than sulphoaluminate cement in EC preparation. EC developed from S-CM had a 13.8% lower alkalinity, better root growth and a 47.5% higher dry weight of plants than EC developed from cement. This study provides a new approach for high value-added recycling of STM.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"7 2","pages":"243 - 257"},"PeriodicalIF":0.0,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145168201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-21DOI: 10.1007/s42768-025-00233-6
Yanjun Hu, Zhenxing Luo, Long Jiao, Caimeng Yu, Jian Li, Qianqian Guo, Jian Song
The spread of pine nematode disease caused by epidemic wood poses a great challenge to the environment, and there is an urgent need to develop effective processing methods; however, Ca/Fe-rich sludge ash can improve the pyrolysis properties of biomass. Therefore, this paper focuses on the pyrolysis mechanism of epidemic wood with the addition of Ca/Fe-rich sludge ash. The presence of Ca-rich sludge ash was found to extend the pyrolytic temperature window of epidemic wood, intensify the cracking of its volatile constituents, and extend its reaction duration. At the same time, the Ca-rich sludge reduces the pyrolysis activation energy to 152.39 kJ/mol. The Fe-rich sludge ash demonstrated the capacity to lower the energy barriers during the initial phase of pyrolysis. Concurrently, the Ca-rich sludge ash accelerated the dehydration reaction of the epidemic wood, leading to 21.02% and 30.69% increases in the contents of acids and ketones in the pyrolytic oil, respectively. The Fe-rich sludge ash contributed to a notable 14.52% increase in aromatic compounds in the oil and a 19.14% decrease in alcoholic compounds. Additionally, the Ca-rich sludge ash accelerated the decomposition of lipid organic matter at elevated temperatures, enriching the pyrolytic char with more unsaturated bonds. This research lays a theoretical foundation for the safe and efficacious thermal decomposition of epidemic wood, thereby enhancing its utilization within the forestry industry.
{"title":"The catalytic activity of Ca/Fe-rich incineration ash in the pyrolysis of epidemic wood","authors":"Yanjun Hu, Zhenxing Luo, Long Jiao, Caimeng Yu, Jian Li, Qianqian Guo, Jian Song","doi":"10.1007/s42768-025-00233-6","DOIUrl":"10.1007/s42768-025-00233-6","url":null,"abstract":"<div><p>The spread of pine nematode disease caused by epidemic wood poses a great challenge to the environment, and there is an urgent need to develop effective processing methods; however, Ca/Fe-rich sludge ash can improve the pyrolysis properties of biomass. Therefore, this paper focuses on the pyrolysis mechanism of epidemic wood with the addition of Ca/Fe-rich sludge ash. The presence of Ca-rich sludge ash was found to extend the pyrolytic temperature window of epidemic wood, intensify the cracking of its volatile constituents, and extend its reaction duration. At the same time, the Ca-rich sludge reduces the pyrolysis activation energy to 152.39 kJ/mol. The Fe-rich sludge ash demonstrated the capacity to lower the energy barriers during the initial phase of pyrolysis. Concurrently, the Ca-rich sludge ash accelerated the dehydration reaction of the epidemic wood, leading to 21.02% and 30.69% increases in the contents of acids and ketones in the pyrolytic oil, respectively. The Fe-rich sludge ash contributed to a notable 14.52% increase in aromatic compounds in the oil and a 19.14% decrease in alcoholic compounds. Additionally, the Ca-rich sludge ash accelerated the decomposition of lipid organic matter at elevated temperatures, enriching the pyrolytic char with more unsaturated bonds. This research lays a theoretical foundation for the safe and efficacious thermal decomposition of epidemic wood, thereby enhancing its utilization within the forestry industry.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"7 2","pages":"259 - 272"},"PeriodicalIF":0.0,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145168012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-09DOI: 10.1007/s42768-025-00228-3
Kai Qi Tan, Wen Da Oh, Mohd Azmier Ahmad, Siew Chun Low
The increased public health awareness in the post corona virus disease 2019 era and the usage of healthcare and cleanroom facilities have contributed to the escalation of the global face mask waste disposal. This study investigates the catalytic pyrolysis of face mask waste into hydrocarbon-rich gases, which holds significant value as prospective carbonaceous nanomaterial (CNM) precursors. The pyrolysis condition was fixed at 500 °C with a heating rate of 20 °C/min. The catalyst, Ni/ZSM-5 was produced from different metal impregnation strategies with various metal precursors namely nickel (Ni), magnesium (Mg), and calcium (Ca). Unlike conventional pyrolysis which focuses on liquid yield, the innovative multi-zone pyrolysis reactor with Ni/ZSM-5 produced an impressive gas yield of 47.0% (mass fraction), of which 79.1% was hydrocarbon gas that could be useful for promising CNM production. The crystallinity of Ni/ZSM-5 and the composition of gas product were largely maintained even after regeneration. Individual and mixed polymer kinetics studies were done using the model-free Ozawa–Flynn–Wall (OFW) method to obtained the activation energy, which was reduced by 9.4% when the Ni/ZSM-5 catalyst was introduced. These results indicate that the viability of Ni/ZSM-5 in reducing the reaction activation energy while concurrently improving the gas yield and quality for potential CNM production. This study improves the optimization of catalytic pyrolysis processes for producing high-quality non-condensable hydrocarbon gas, particularly in sustainable material synthesis.
{"title":"Sustainable catalytic upcycling of medical face mask wastes into hydrocarbon-rich gases for potential carbonaceous nanomaterial production","authors":"Kai Qi Tan, Wen Da Oh, Mohd Azmier Ahmad, Siew Chun Low","doi":"10.1007/s42768-025-00228-3","DOIUrl":"10.1007/s42768-025-00228-3","url":null,"abstract":"<div><p>The increased public health awareness in the post corona virus disease 2019 era and the usage of healthcare and cleanroom facilities have contributed to the escalation of the global face mask waste disposal. This study investigates the catalytic pyrolysis of face mask waste into hydrocarbon-rich gases, which holds significant value as prospective carbonaceous nanomaterial (CNM) precursors. The pyrolysis condition was fixed at 500 °C with a heating rate of 20 °C/min. The catalyst, Ni/ZSM-5 was produced from different metal impregnation strategies with various metal precursors namely nickel (Ni), magnesium (Mg), and calcium (Ca). Unlike conventional pyrolysis which focuses on liquid yield, the innovative multi-zone pyrolysis reactor with Ni/ZSM-5 produced an impressive gas yield of 47.0% (mass fraction), of which 79.1% was hydrocarbon gas that could be useful for promising CNM production. The crystallinity of Ni/ZSM-5 and the composition of gas product were largely maintained even after regeneration. Individual and mixed polymer kinetics studies were done using the model-free Ozawa–Flynn–Wall (OFW) method to obtained the activation energy, which was reduced by 9.4% when the Ni/ZSM-5 catalyst was introduced. These results indicate that the viability of Ni/ZSM-5 in reducing the reaction activation energy while concurrently improving the gas yield and quality for potential CNM production. This study improves the optimization of catalytic pyrolysis processes for producing high-quality non-condensable hydrocarbon gas, particularly in sustainable material synthesis.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"7 2","pages":"199 - 215"},"PeriodicalIF":0.0,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145163763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-08DOI: 10.1007/s42768-025-00225-6
Yingying Han, Cheng Zhang, Xia Li, Jiangshan Li, Le Fang
China's extensive sludge production has necessitated the development of advanced pyrolysis modification techniques, particularly those involving alkaline metals such as CaO and KOH. Previous studies have shown that CaO effectively captures phosphorus, whereas KOH promotes organic cracking. This study investigated dual-alkali-driven sludge pyrolysis processes for the production of biochar with stabilized heavy metals and enriched phosphorus contents. To elucidate the mechanisms underlying the pyrolysis process, advanced analytical techniques, including thermogravimetric analysis-Fourier transform infrared-gas chromatography–mass spectrometry (TG-FTIR-GC–MS), were employed to analyze the gas emissions from the CaO/KOH-modified sludge. Furthermore, infrared spectroscopy and X-ray diffraction phase analysis were used to characterize the resulting biochar. The results demonstrate that the influence of alkali metals on biochar composition and structure is closely related to the content of Lewis acids and bases in the sludge, and the reaction paths of CaO/KOH with typical functional groups (such as –COOH, –C–N and-C–OH) are given. For instance, CaO facilitates nitrogen volatilization, reducing its content by 17%–38%, whereas KOH retains nitrogen, increasing its content by 17%. The synergistic application of CaO and KOH significantly enhances the apatite phosphorus (AP) and total phosphorus (TP) ratio from 24%–35% to 87%–88%, and the AP to non-apatite inorganic phosphorus (NAIP) ratio from 0.32–0.54 to 5.74–43.77, thereby enabling the tuning of soil phosphorus availability and slow-release properties. Additionally, while CaO promotes phosphorus accumulation and assists in the sequestration of heavy metals, particularly Cr and Zn, KOH activates certain metals in the slag, potentially reducing their retention in the biochar.
{"title":"Mechanism and product analysis of sludge pyrolysis driven by double alkali synergy","authors":"Yingying Han, Cheng Zhang, Xia Li, Jiangshan Li, Le Fang","doi":"10.1007/s42768-025-00225-6","DOIUrl":"10.1007/s42768-025-00225-6","url":null,"abstract":"<div><p>China's extensive sludge production has necessitated the development of advanced pyrolysis modification techniques, particularly those involving alkaline metals such as CaO and KOH. Previous studies have shown that CaO effectively captures phosphorus, whereas KOH promotes organic cracking. This study investigated dual-alkali-driven sludge pyrolysis processes for the production of biochar with stabilized heavy metals and enriched phosphorus contents. To elucidate the mechanisms underlying the pyrolysis process, advanced analytical techniques, including thermogravimetric analysis-Fourier transform infrared-gas chromatography–mass spectrometry (TG-FTIR-GC–MS), were employed to analyze the gas emissions from the CaO/KOH-modified sludge. Furthermore, infrared spectroscopy and X-ray diffraction phase analysis were used to characterize the resulting biochar. The results demonstrate that the influence of alkali metals on biochar composition and structure is closely related to the content of Lewis acids and bases in the sludge, and the reaction paths of CaO/KOH with typical functional groups (such as –COOH, –C–N and-C–OH) are given. For instance, CaO facilitates nitrogen volatilization, reducing its content by 17%–38%, whereas KOH retains nitrogen, increasing its content by 17%. The synergistic application of CaO and KOH significantly enhances the apatite phosphorus (AP) and total phosphorus (TP) ratio from 24%–35% to 87%–88%, and the AP to non-apatite inorganic phosphorus (NAIP) ratio from 0.32–0.54 to 5.74–43.77, thereby enabling the tuning of soil phosphorus availability and slow-release properties. Additionally, while CaO promotes phosphorus accumulation and assists in the sequestration of heavy metals, particularly Cr and Zn, KOH activates certain metals in the slag, potentially reducing their retention in the biochar.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"7 2","pages":"185 - 197"},"PeriodicalIF":0.0,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145163383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Oil palm fronds (OPF) are a potential solid fuel source, similar to empty palm fruit bunches (EFB), yet high potassium (K) content can cause fouling and deposition in boiler systems. To mitigate these issues, an acidic torrefaction liquid pretreatment was applied to reduce OPF potassium level, and co-torrefaction with waste cooking oil (WCO) was employed to enhance the resulting biochar’s higher heating value (HHV). X-ray fluorescence (XRF) analysis indicated that acidic pretreatment lowered potassium content from 35.48% to 20.91%, a reduction of approximately 41%, thereby significantly diminishing K-induced fouling risk. Through systematic variation of pretreatment temperature (30–50 °C), duration (45–75 min), WOPF-to-WCO ratio (1:0–3:1, mass/mass), and co-torrefaction temperature (200–300 °C), optimal conditions were identified at 50 °C for 75 min, an WOPF-to-WCO ratio of 1:1, and co-torrefaction at 250 °C. Under these parameters, WCO contributed additional hydrocarbons, increasing fixed carbon content and reducing oxygen level, thereby improving the fuel stability and HHV. The biochar exhibited a mass yield of 60.95%, an energy yield of 87.43%, and a HHV of 31.97 MJ/kg, surpassing the performance of untreated OPF biochar. By simultaneously reducing potassium content and enriching carbon and hydrogen fractions, this optimized biochar exhibits enhanced combustion properties, positioning it as a sustainable alternative to coal with higher energy density and lower operational risk in combustion systems.
{"title":"High-efficiency biochar production from oil palm fronds using acidic pretreatment and co-torrefaction with waste cooking oil","authors":"Anisa Mutamima, Sunarno Sunarno, Indra Purnama, Nurfatihayati Nurfatihayati, Akmal Novendri, Rinalsi Anesta, Rozanna Sri Irianty","doi":"10.1007/s42768-025-00229-2","DOIUrl":"10.1007/s42768-025-00229-2","url":null,"abstract":"<div><p>Oil palm fronds (OPF) are a potential solid fuel source, similar to empty palm fruit bunches (EFB), yet high potassium (K) content can cause fouling and deposition in boiler systems. To mitigate these issues, an acidic torrefaction liquid pretreatment was applied to reduce OPF potassium level, and co-torrefaction with waste cooking oil (WCO) was employed to enhance the resulting biochar’s higher heating value (HHV). X-ray fluorescence (XRF) analysis indicated that acidic pretreatment lowered potassium content from 35.48% to 20.91%, a reduction of approximately 41%, thereby significantly diminishing K-induced fouling risk. Through systematic variation of pretreatment temperature (30–50 °C), duration (45–75 min), WOPF-to-WCO ratio (1:0–3:1, mass/mass), and co-torrefaction temperature (200–300 °C), optimal conditions were identified at 50 °C for 75 min, an WOPF-to-WCO ratio of 1:1, and co-torrefaction at 250 °C. Under these parameters, WCO contributed additional hydrocarbons, increasing fixed carbon content and reducing oxygen level, thereby improving the fuel stability and HHV. The biochar exhibited a mass yield of 60.95%, an energy yield of 87.43%, and a HHV of 31.97 MJ/kg, surpassing the performance of untreated OPF biochar. By simultaneously reducing potassium content and enriching carbon and hydrogen fractions, this optimized biochar exhibits enhanced combustion properties, positioning it as a sustainable alternative to coal with higher energy density and lower operational risk in combustion systems.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"7 2","pages":"229 - 242"},"PeriodicalIF":0.0,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s42768-025-00229-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145163083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-05DOI: 10.1007/s42768-025-00223-8
Chenglong Lu, Xuan Yu, Guohao Yang, Qianqian Guo, Long Jiao, Jinxiang Lin, Kai Deng, Yanjun Hu
Improper handling of heavy metal-containing solid waste poses significant environmental risks. However, developing an effective heavy metal elimination method is still a challenge. Our study introduces a novel method of staggered chlorination roasting. The volatilization and removal effects of two chlorinating agents, NH₄Cl and CaCl₂, on typical key heavy metals, Zn and Cu, were investigated. Compared with the use of a single chlorinating agent, this method, which uses NH₄Cl for low-temperature decomposition and CaCl₂ for high-temperature reactions, significantly extends the chlorination reaction time, overtly enhancing the chlorination volatilization effect. This study elucidated the influence of the chlorinating agent content, temperature, and time on the elimination of heavy metal oxides. The results demonstrated that when the two chlorinating agents were added at a ratio of 2:3, roasting at 1100 °C for 60 min resulted in the highest volatilization rates of Zn (99.9%) and Cu (98.7%). Thermodynamic equilibrium and equilibrium phase composition calculations were conducted to explore the effects of the chlorinating agents and mineral components (SiO₂, Al₂O₃, Fe₂O₃, and CaO) on chlorination roasting. In the staggered chlorination mode, the chlorine-containing gases generated effectively mitigate the influence of mineral components, thereby suppressing interactions between oxidized heavy metals and mineral constituents. This suppression enhances the chlorination and volatilization of heavy metals. This study proposes a novel staggered chlorination roasting method based on composite chlorinating agents, offering a new approach for the collaborative and efficient removal of multiple heavy metals from solid waste.
{"title":"Mechanistic insights into the chlorination volatilization of oxidized heavy metals via novel staggered chlorination roasting","authors":"Chenglong Lu, Xuan Yu, Guohao Yang, Qianqian Guo, Long Jiao, Jinxiang Lin, Kai Deng, Yanjun Hu","doi":"10.1007/s42768-025-00223-8","DOIUrl":"10.1007/s42768-025-00223-8","url":null,"abstract":"<div><p>Improper handling of heavy metal-containing solid waste poses significant environmental risks. However, developing an effective heavy metal elimination method is still a challenge. Our study introduces a novel method of staggered chlorination roasting. The volatilization and removal effects of two chlorinating agents, NH₄Cl and CaCl₂, on typical key heavy metals, Zn and Cu, were investigated. Compared with the use of a single chlorinating agent, this method, which uses NH₄Cl for low-temperature decomposition and CaCl₂ for high-temperature reactions, significantly extends the chlorination reaction time, overtly enhancing the chlorination volatilization effect. This study elucidated the influence of the chlorinating agent content, temperature, and time on the elimination of heavy metal oxides. The results demonstrated that when the two chlorinating agents were added at a ratio of 2:3, roasting at 1100 °C for 60 min resulted in the highest volatilization rates of Zn (99.9%) and Cu (98.7%). Thermodynamic equilibrium and equilibrium phase composition calculations were conducted to explore the effects of the chlorinating agents and mineral components (SiO₂, Al₂O₃, Fe₂O₃, and CaO) on chlorination roasting. In the staggered chlorination mode, the chlorine-containing gases generated effectively mitigate the influence of mineral components, thereby suppressing interactions between oxidized heavy metals and mineral constituents. This suppression enhances the chlorination and volatilization of heavy metals. This study proposes a novel staggered chlorination roasting method based on composite chlorinating agents, offering a new approach for the collaborative and efficient removal of multiple heavy metals from solid waste.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"7 2","pages":"151 - 163"},"PeriodicalIF":0.0,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145162608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-04DOI: 10.1007/s42768-025-00227-4
Dongxu Zhang, Huizhong Han, Jianguo Zhu
China possesses abundant reserves of high-alkali coal, however, its combustion presents challenges such as slagging and fouling. Achieving efficient and clean combustion of high-alkali coal remains a significant technical challenge. This study utilizes novel circulating fluidized bed (CFB) preheating combustion technology to investigate the effects of varying air equivalence ratios on the preheating, combustion, and NOx emission characteristics of high-alkali coal in a kW-level hot-state experimental platform. Results indicate that the preheater intensifies the fragmentation of high-alkali coal particles, decreasing the median particle size (d50) from 710.9 μm in high-alkali coal to 17.1 μm in preheated char. At an air equivalence ratio of 0.35, the calorific value of the preheated coal gas reaches a peak of 2.46 MJ/Nm3. Across various air equivalence ratios, the NH3 concentration in the preheated coal gas consistently exceed those of HCN. With the air equivalence ratio increases, the release rates of C, N, and S from the high-alkali coal also rise, while the CO/CO2 ratio of the preheated coal gas remains below 1.0. And the S release rate is lower than that of C and N. During the combustion of preheated fuel in the combustion chamber, the temperature distribution remains uniform, with NOx emissions ranging from 200 to 230 mg/m3. The minimum conversion ratio of coal N to NOx in this system is 10.8%. This investigation might support the development and application of high-alkali coal combustion technology.
{"title":"Preheating and combustion characteristics of high-alkali coal with a novel circulating fluidized bed route","authors":"Dongxu Zhang, Huizhong Han, Jianguo Zhu","doi":"10.1007/s42768-025-00227-4","DOIUrl":"10.1007/s42768-025-00227-4","url":null,"abstract":"<div><p>China possesses abundant reserves of high-alkali coal, however, its combustion presents challenges such as slagging and fouling. Achieving efficient and clean combustion of high-alkali coal remains a significant technical challenge. This study utilizes novel circulating fluidized bed (CFB) preheating combustion technology to investigate the effects of varying air equivalence ratios on the preheating, combustion, and NO<sub><i>x</i></sub> emission characteristics of high-alkali coal in a kW-level hot-state experimental platform. Results indicate that the preheater intensifies the fragmentation of high-alkali coal particles, decreasing the median particle size (d<sub>50</sub>) from 710.9 μm in high-alkali coal to 17.1 μm in preheated char. At an air equivalence ratio of 0.35, the calorific value of the preheated coal gas reaches a peak of 2.46 MJ/Nm<sup>3</sup>. Across various air equivalence ratios, the NH<sub>3</sub> concentration in the preheated coal gas consistently exceed those of HCN. With the air equivalence ratio increases, the release rates of C, N, and S from the high-alkali coal also rise, while the CO/CO<sub>2</sub> ratio of the preheated coal gas remains below 1.0. And the S release rate is lower than that of C and N. During the combustion of preheated fuel in the combustion chamber, the temperature distribution remains uniform, with NO<sub><i>x</i></sub> emissions ranging from 200 to 230 mg/m<sup>3</sup>. The minimum conversion ratio of coal N to NO<sub><i>x</i></sub> in this system is 10.8%. This investigation might support the development and application of high-alkali coal combustion technology.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":807,"journal":{"name":"Waste Disposal & Sustainable Energy","volume":"7 2","pages":"217 - 228"},"PeriodicalIF":0.0,"publicationDate":"2025-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145161943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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