Pub Date : 2025-02-08DOI: 10.1016/j.wasman.2025.01.036
Donghui Li , Shuyao Feng , Chao He , Lijuan Men , Jiangshuo Li , Jiafeng Zhang , Yefeng Zhou
Traditional hydrometallurgical recycling methods present challenges including complex processes, significant metal loss, and high costs. To address these issues, this work introduces a facile and efficient recycling method for spent ternary cathode materials, which combines acid leaching and oxidation as well as ammonia leaching. Firstly, careful control of the phosphoric acid concentration and sodium persulfate dosage allows for the selective leaching of Li and Ni in the process of acid leaching and oxidation, and thus their leaching efficiencies can reach as high as 99.3 % and 97.2 % respectively. Meanwhile, Co and Mn can be separated in the form of Co3O4 and MnO2 remaining in the waste residues. Secondly, based on the stability difference of complexes formed by cobalt and manganese with ammonia, Co can be selectively leached from waste residue through ammonia leaching, with the leaching efficiency reaching 93.2 %, while Mn is separated via reacting with CO32− in the solution to form MnCO3. Moreover, the mechanisms of selectively leaching Li and Ni during acid leaching and oxidation processes are revealed using characterization techniques such as XRD, ICP, SEM-EDS, and thermodynamic analysis. Finally, economic analysis shows that the benefits of this approach in terms of battery reuse are considerable, and there are clear advantages in terms of process simplification and operational safety. Compared to traditional hydrometallurgical recovery methods, which typically involve sequential separation after metal leaching, the proposed method achieves simultaneous leaching and separation of metals, thereby simplifying the recovery process and reducing metal losses.
{"title":"A facile and efficient recovery method of valuable metals from spent lithium-ion batteries via simultaneous leaching and separation strategy","authors":"Donghui Li , Shuyao Feng , Chao He , Lijuan Men , Jiangshuo Li , Jiafeng Zhang , Yefeng Zhou","doi":"10.1016/j.wasman.2025.01.036","DOIUrl":"10.1016/j.wasman.2025.01.036","url":null,"abstract":"<div><div>Traditional hydrometallurgical recycling methods present challenges including complex processes, significant metal loss, and high costs. To address these issues, this work introduces a facile and efficient recycling method for spent ternary cathode materials, which combines acid leaching and oxidation as well as ammonia leaching. Firstly, careful control of the phosphoric acid concentration and sodium persulfate dosage allows for the selective leaching of Li and Ni in the process of acid leaching and oxidation, and thus their leaching efficiencies can reach as high as 99.3 % and 97.2 % respectively. Meanwhile, Co and Mn can be separated in the form of Co<sub>3</sub>O<sub>4</sub> and MnO<sub>2</sub> remaining in the waste residues. Secondly, based on the stability difference of complexes formed by cobalt and manganese with ammonia, Co can be selectively leached from waste residue through ammonia leaching, with the leaching efficiency reaching 93.2 %, while Mn is separated via reacting with CO<sub>3</sub><sup>2−</sup> in the solution to form MnCO<sub>3</sub>. Moreover, the mechanisms of selectively leaching Li and Ni during acid leaching and oxidation processes are revealed using characterization techniques such as XRD, ICP, SEM-EDS, and thermodynamic analysis. Finally, economic analysis shows that the benefits of this approach in terms of battery reuse are considerable, and there are clear advantages in terms of process simplification and operational safety. Compared to traditional hydrometallurgical recovery methods, which typically involve sequential separation after metal leaching, the proposed method achieves simultaneous leaching and separation of metals, thereby simplifying the recovery process and reducing metal losses.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"195 ","pages":"Pages 220-230"},"PeriodicalIF":7.1,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143369649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-08DOI: 10.1016/j.wasman.2025.02.007
Aleksandra Wdowczyk , Justyna Koc-Jurczyk , Łukasz Jurczyk , Agata Szymańska–Pulikowska , Bernard Gałka
The problem of leachate generated at municipal landfills, and the challenges of its logistics and disposal, are forcing the search for new, environmentally friendly methods of treatment, especially when it can be applied in situ. The method that combines constructed wetland system with conventional activated sludge process, hereinafter referred to as Vegetation-Activated Sludge Process (V-ASP), may be an interesting alternative, but still require research and comprehensive evaluation. Therefore, this study aimed to verify the effectiveness of V-ASP in the treatment of landfill leachate, the impact of two different fillings (biochar and zeolite) and hydraulic retention time (HRT) on the final removal of selected pollutants and the stability of the treatment process. The experiment was conducted for 138 days on a laboratory-scale V-ASP system layout as sequential batch reactors operating in a 24-hour cycle. The removal efficacy of N-NH4+, regardless of the substrate and the HRT that varied from 3 to 14 days, remained at around 99 %. Longer HRT favoured higher total nitrogen (TN) reduction in all examined variants, with the highest achieved at 14 days, and average TN removal ranging from 38 to 54 %. Also, the chemical oxygen demand removal efficacy increased along with HRT, while phosphorus removal efficacy remained low in all examined systems throughout the experiment. The proposed technological system fits into new trends in environmental engineering, combining technical, pro-environmental solutions and enabling potential reductions in material and energy costs.
{"title":"Removal of selected pollutants from landfill leachate in the vegetation-activated sludge process","authors":"Aleksandra Wdowczyk , Justyna Koc-Jurczyk , Łukasz Jurczyk , Agata Szymańska–Pulikowska , Bernard Gałka","doi":"10.1016/j.wasman.2025.02.007","DOIUrl":"10.1016/j.wasman.2025.02.007","url":null,"abstract":"<div><div>The problem of leachate generated at municipal landfills, and the challenges of its logistics and disposal, are forcing the search for new, environmentally friendly methods of treatment, especially when it can be applied <em>in situ</em>. The method that combines constructed wetland system with conventional activated sludge process, hereinafter referred to as Vegetation-Activated Sludge Process (V-ASP), may be an interesting alternative, but still require research and comprehensive evaluation. Therefore, this study aimed to verify the effectiveness of V-ASP in the treatment of landfill leachate, the impact of two different fillings (biochar and zeolite) and hydraulic retention time (HRT) on the final removal of selected pollutants and the stability of the treatment process. The experiment was conducted for 138 days on a laboratory-scale V-ASP system layout as sequential batch reactors operating in a 24-hour cycle. The removal efficacy of N-NH<sub>4</sub><sup>+</sup>, regardless of the substrate and the HRT that varied from 3 to 14 days, remained at around 99 %. Longer HRT favoured higher total nitrogen (TN) reduction in all examined variants, with the highest achieved at 14 days, and average TN removal ranging from 38 to 54 %. Also, the chemical oxygen demand removal efficacy increased along with HRT, while phosphorus removal efficacy remained low in all examined systems throughout the experiment. The proposed technological system fits into new trends in environmental engineering, combining technical, pro-environmental solutions and enabling potential reductions in material and energy costs.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"195 ","pages":"Pages 209-219"},"PeriodicalIF":7.1,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143348828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-08DOI: 10.1016/j.wasman.2025.02.005
Shuai Li , Rui Qu , Erfeng Hu , Zuohua Liu , Qingang Xiong , Jianglong Yu , Yongfu Zeng , Moshan Li
The efficient co-utilization of biomass and waste plastics is a key method to address the widely concerned environmental problem and replace traditional energy. Co-pyrolysis behaviors and synergistic effects of furfural residues (FR) and polyethylene (PE) were studied by TG and artificial neural network (ANN). The FWO and KAS method were employed to analyze the kinetics and thermodynamics. The average activation energies calculated by FWO and KAS methods were 269.17 kJ/mol and 276.77 kJ/mol, respectively. The ANN achieved the minimum validation error at 79 iterations, and its best performance was at the 73rd iteration, with a minimum MSE of 0.0073503. Co-pyrolysis experiments were conducted in a fast heating reactor with different temperatures and ratios. Product distributions were analyzed using GC–MS, simulated distillation, and Pearson correlation coefficient analysis. As the co-pyrolysis temperature increased from 500 to 800 °C, the bio-oil yield initially rose from 19.20 % to a peak of 21.97 % at 600 °C, then declined to 12.48 %. Co-pyrolysis promoted hydrocarbon production while reducing oxygenate compounds in the bio-oil. Pearson correlation analysis revealed that bio-oil yield exhibited a positive correlation with water and char yields at different temperatures and ratios, while showing an inverse correlation with wax yield. This research contributes to advancing our understanding of co-pyrolysis characteristics of FR and PE, with implications for optimizing bio-oil production and facilitating sustainable waste utilization strategies.
{"title":"Co-pyrolysis kinetics and enhanced synergy for furfural residues and polyethylene using artificial neural network and fast heating","authors":"Shuai Li , Rui Qu , Erfeng Hu , Zuohua Liu , Qingang Xiong , Jianglong Yu , Yongfu Zeng , Moshan Li","doi":"10.1016/j.wasman.2025.02.005","DOIUrl":"10.1016/j.wasman.2025.02.005","url":null,"abstract":"<div><div>The efficient co-utilization of biomass and waste plastics is a key method to address the widely concerned environmental problem and replace traditional energy. Co-pyrolysis behaviors and synergistic effects of furfural residues (FR) and polyethylene (PE) were studied by TG and artificial neural network (ANN). The FWO and KAS method were employed to analyze the kinetics and thermodynamics. The average activation energies calculated by FWO and KAS methods were 269.17 kJ/mol and 276.77 kJ/mol, respectively. The ANN achieved the minimum validation error at 79 iterations, and its best performance was at the 73rd iteration, with a minimum MSE of 0.0073503. Co-pyrolysis experiments were conducted in a fast heating reactor with different temperatures and ratios. Product distributions were analyzed using GC–MS, simulated distillation, and Pearson correlation coefficient analysis. As the co-pyrolysis temperature increased from 500 to 800 °C, the bio-oil yield initially rose from 19.20 % to a peak of 21.97 % at 600 °C, then declined to 12.48 %. Co-pyrolysis promoted hydrocarbon production while reducing oxygenate compounds in the bio-oil. Pearson correlation analysis revealed that bio-oil yield exhibited a positive correlation with water and char yields at different temperatures and ratios, while showing an inverse correlation with wax yield. This research contributes to advancing our understanding of co-pyrolysis characteristics of FR and PE, with implications for optimizing bio-oil production and facilitating sustainable waste utilization strategies.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"195 ","pages":"Pages 177-188"},"PeriodicalIF":7.1,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-08DOI: 10.1016/j.wasman.2025.02.012
Jicheng Hui , Jiangong Lin , Shujun Zhu , Zhaoyang Li , Xiaoyu Zhang , Xiaoyang Cao , Jianguo Zhu , Qinggang Lyu
The improper disposal of coal gasification fly ash (CGFA) and coal gangue (CG) is highly susceptible to environmental pollution. Preheating combustion is a proven technology for the efficient combustion of solid fuels. On the basis of this technology and combining the complementary physical properties of CGFA and CG, the synergistic combustion of these two typical solid wastes is expected to occur. In this study, the preheating modification and co-combustion characteristics of CGFA and CG with different blending ratios were investigated. The evolution of the physicochemical structure of the activated char was analyzed via a particle size analyzer, scanning electron microscope, N2 adsorption–desorption and Raman spectroscopy. The results indicated that stable operation of the preheated combustion system could be achieved when the blending ratio of CG was 25 %-50 %. The apparent structure of the blended fuel can be improved by CGFA, while the specific surface area and chemical reactivity of the resulting char can be increased significantly. The highest activity of the preheated char was achieved at a blending ratio of 25 % (R = 25 %). In addition, there was a synergistic effect between the fixed carbon in CGFA and the volatiles in CG during co-combustion. The combustion efficiency of the blended fuel was improved at blending ratios of 25 % to 50 %. With the comprehensive evaluation of preheating modification and co-combustion characteristics, the optimal blending ratio of CG was R = 25 %. In this case, the NO and N2O emissions were 121 mg/cm3 (@6% O2) and 14 mg/cm3 (@6% O2), respectively.
{"title":"Co-combustion characteristics of coal gasification fly ash and coal gangue preheated by circulating fluidized bed","authors":"Jicheng Hui , Jiangong Lin , Shujun Zhu , Zhaoyang Li , Xiaoyu Zhang , Xiaoyang Cao , Jianguo Zhu , Qinggang Lyu","doi":"10.1016/j.wasman.2025.02.012","DOIUrl":"10.1016/j.wasman.2025.02.012","url":null,"abstract":"<div><div>The improper disposal of coal gasification fly ash (CGFA) and coal gangue (CG) is highly susceptible to environmental pollution. Preheating combustion is a proven technology for the efficient combustion of solid fuels. On the basis of this technology and combining the complementary physical properties of CGFA and CG, the synergistic combustion of these two typical solid wastes is expected to occur. In this study, the preheating modification and co-combustion characteristics of CGFA and CG with different blending ratios were investigated. The evolution of the physicochemical structure of the activated char was analyzed via a particle size analyzer, scanning electron microscope, N<sub>2</sub> adsorption–desorption and Raman spectroscopy. The results indicated that stable operation of the preheated combustion system could be achieved when the blending ratio of CG was 25 %-50 %. The apparent structure of the blended fuel can be improved by CGFA, while the specific surface area and chemical reactivity of the resulting char can be increased significantly. The highest activity of the preheated char was achieved at a blending ratio of 25 % (<em>R</em> = 25 %). In addition, there was a synergistic effect between the fixed carbon in CGFA and the volatiles in CG during co-combustion. The combustion efficiency of the blended fuel was improved at blending ratios of 25 % to 50 %. With the comprehensive evaluation of preheating modification and co-combustion characteristics, the optimal blending ratio of CG was <em>R</em> = 25 %. In this case, the NO and N<sub>2</sub>O emissions were 121 mg/cm<sup>3</sup> (@6% O<sub>2</sub>) and 14 mg/cm<sup>3</sup> (@6% O<sub>2</sub>), respectively.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"195 ","pages":"Pages 200-208"},"PeriodicalIF":7.1,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143348827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-07DOI: 10.1016/j.wasman.2025.02.002
Jun Ma , Ming Ma , Jiangshan Li , Qirui Yang , Yong Wan , Kai Zhao , Yi Zhang , Lei Liu , Xunchang Fei
Microplastics (MPs), an emerging pollutant, have garnered global attention as significant environmental concerns. Landfills are the major sources of MPs. However, research on the distribution and characteristics of MPs in leachate and underneath soil of informal landfills remains limited. This study investigated the abundance, polymer type, size, and morphology of MPs in 6 leachate samples and 18 underneath soil samples at different depths from two informal landfills. The ranges of MPs abundance in leachate and underneath soil from landfills were 4,010–33,213 items/Land 592–870 to 47,819 items/kg, related to the landfilled waste composition. MPs size between 20 and 100 µm accounted for the highest proportion (70 %). The fragmentation coefficient α in the underneath soil was higher than that in the leachate, indicating smaller MPs were more likely to migrate into underneath soil after filtration. The fibrous MPs proportion was below 22 %, while the fragmented MPs was more than 78 %. Large fibrous MPs were detected in the underneath soil in landfill A. Polyethylene Terephthalate (PET), Polyurethane (PU) and Polystyrene (PS) were the predominant MPs polymers types in leachate and underneath soil. Polypropylene (PP) was primarily concentrated in the upper and middle underneath soil layers, and Polyurethane (PU) was predominantly in the middle and lower layers. Principal component analysis (PCA) results indicated that geographical factors significantly influenced the distribution and characteristics of MPs. This study revealed the distribution of MPs in leachate and underneath soil at different depths, providing a valuable reference for the risk assessment of MPs pollution.
{"title":"Distribution and characteristics of Microplastics in leachate and underneath soil of two informal landfills","authors":"Jun Ma , Ming Ma , Jiangshan Li , Qirui Yang , Yong Wan , Kai Zhao , Yi Zhang , Lei Liu , Xunchang Fei","doi":"10.1016/j.wasman.2025.02.002","DOIUrl":"10.1016/j.wasman.2025.02.002","url":null,"abstract":"<div><div>Microplastics (MPs), an emerging pollutant, have garnered global attention as significant environmental concerns. Landfills are the major sources of MPs. However, research on the distribution and characteristics of MPs in leachate and underneath soil of informal landfills remains limited. This study investigated the abundance, polymer type, size, and morphology of MPs in 6 leachate samples and 18 underneath soil samples at different depths from two informal landfills. The ranges of MPs abundance in leachate and underneath soil from landfills were 4,010–33,213 items/Land 592–870 to 47,819 items/kg, related to the landfilled waste composition. MPs size between 20 and 100 µm accounted for the highest proportion (70 %). The fragmentation coefficient α in the underneath soil was higher than that in the leachate, indicating smaller MPs were more likely to migrate into underneath soil after filtration. The fibrous MPs proportion was below 22 %, while the fragmented MPs was more than 78 %. Large fibrous MPs were detected in the underneath soil in landfill A. Polyethylene Terephthalate (PET), Polyurethane (PU) and Polystyrene (PS) were the predominant MPs polymers types in leachate and underneath soil. Polypropylene (PP) was primarily concentrated in the upper and middle underneath soil layers, and Polyurethane (PU) was predominantly in the middle and lower layers. Principal component analysis (PCA) results indicated that geographical factors significantly influenced the distribution and characteristics of MPs. This study revealed the distribution of MPs in leachate and underneath soil at different depths, providing a valuable reference for the risk assessment of MPs pollution.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"195 ","pages":"Pages 155-166"},"PeriodicalIF":7.1,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143337955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-07DOI: 10.1016/j.wasman.2025.02.001
Shanshan E. , Boyang Xu , Bo Niu , Zhenming Xu
Spent disposable Zn-Mn and Zn-C batteries are important resources for recycling. Acid leaching is the crucial step in the hydrometallurgy process for recycling Zn and Mn from these spent Zn-based batteries. However, to obtain the optimal leaching efficiency, the uncontrollable components in waste feed and various leaching parameters cause numerous replicated optimal experiments, increasing the recovery cost and environmental risks. To solve the issues, we employed machine learning (ML) techniques to construct models to predict Zn and Mn leaching from spent disposable batteries without optimizing experiments. Among four ML algorithms tested, the extreme gradient boosting demonstrated superior predictive performance, achieving an R2 of 0.85–0.98 across the training, test, and verification datasets. An analysis of feature importance indicated that the particle size, waste composition, acid concentration, temperature, and time affected the metal leaching most. This study also revealed the interaction effects of the waste properties and leaching process on the metal leaching. Furthermore, we created a user-friendly graphical user interface (GUI) that enables quick acquisition of metal leaching results, requiring only the measurement of waste particle size and component. Finally, experimental verification confirmed the practicability of the GUI. This study achieves intelligent metal leaching from spent batteries and overcomes the high recovery cost and environmental risks associated with traditional experimental optimizing methods.
{"title":"Intelligent leaching of Zn and Mn from spent disposable batteries to avoid traditional optimizing experiments","authors":"Shanshan E. , Boyang Xu , Bo Niu , Zhenming Xu","doi":"10.1016/j.wasman.2025.02.001","DOIUrl":"10.1016/j.wasman.2025.02.001","url":null,"abstract":"<div><div>Spent disposable Zn-Mn and Zn-C batteries are important resources for recycling. Acid leaching is the crucial step in the hydrometallurgy process for recycling Zn and Mn from these spent Zn-based batteries. However, to obtain the optimal leaching efficiency, the uncontrollable components in waste feed and various leaching parameters cause numerous replicated optimal experiments, increasing the recovery cost and environmental risks. To solve the issues, we employed machine learning (ML) techniques to construct models to predict Zn and Mn leaching from spent disposable batteries without optimizing experiments. Among four ML algorithms tested, the extreme gradient boosting demonstrated superior predictive performance, achieving an R<sup>2</sup> of 0.85–0.98 across the training, test, and verification datasets. An analysis of feature importance indicated that the particle size, waste composition, acid concentration, temperature, and time affected the metal leaching most. This study also revealed the interaction effects of the waste properties and leaching process on the metal leaching. Furthermore, we created a user-friendly graphical user interface (GUI) that enables quick acquisition of metal leaching results, requiring only the measurement of waste particle size and component. Finally, experimental verification confirmed the practicability of the GUI. This study achieves intelligent metal leaching from spent batteries and overcomes the high recovery cost and environmental risks associated with traditional experimental optimizing methods.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"195 ","pages":"Pages 145-154"},"PeriodicalIF":7.1,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143337954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-06DOI: 10.1016/j.wasman.2025.01.032
Jacopo De Tommaso , Federico Galli , Tien Dat Nguyen , Yanfa Zhuang , Jean-Luc Dubois , Gregory S. Patience
Artificial marble, a composite material consisting of 40 % (g g−1) Poly Methyl Methacrylate (PMMA) and 60 % (g g−1) aluminium hydroxide , combines the durability and aesthetics of real marble with the lightweight and moldability of plastic. It is the most sought-after synthetic stone in the world, with a production volume of over 1 million t in 2021. However, due to a high level of cross-linking, mechanical recycling of the composite is impossible, while chemical recycling is achievable, yet unprofitable. The only economically viable recycling solution is to retain the value of both the organic and inorganic fraction of the composite. We investigated the pyrolysis and hydrolysis of post-consumer end-of-life artificial marble to identify possible valorization routes, examining the effects of temperature, water content, catalyst presence, and heating style. Temperature directly accelerates thermolysis, and indirectly hydrolysis. The water inherently present in drives initial hydrolysis, and temperature expedites inorganic fraction dehydration, increasing local water partial pressure near polymer ester sites. Above 350 °C, PMMAeq depolymerizes faster than it hydrolyzes, balancing the effects of temperature on water dehydration with the depletion of available ester sites for hydrolysis. Contrary to intuition, PMMA does not depolymerize to its monomer MMA and then hydrolyze its acid (methacrylic acid); instead, PMMA partially hydrolyzes to poly methacrylic acid (PMAA) while also depolymerizing to MMA. PMAA then dehydrates and degrades, releasing CO and CO2. The optimal method involves a heating ramp that first releases water at 300 °C, minimizing hydrolysis, and then favors MMA production at 400 °C, achieving a 66 % (g g−1) MMA yield. Regardless of the operative conditions, the inorganic fraction transforms from to a -alumina precursor, boehmite. Additionally, the remaining polymer in the residue, about 9 % (g g−1), has the required heat capacity for an energy-self sufficient calcination to -alumina. This dual-phase process not only maximizes MMA recovery but also retains the value of the inorganic fraction, providing a sustainable and economically viable recycling method for artificial marble.
{"title":"Waste artificial marble pyrolysis and hydrolysis","authors":"Jacopo De Tommaso , Federico Galli , Tien Dat Nguyen , Yanfa Zhuang , Jean-Luc Dubois , Gregory S. Patience","doi":"10.1016/j.wasman.2025.01.032","DOIUrl":"10.1016/j.wasman.2025.01.032","url":null,"abstract":"<div><div>Artificial marble, a composite material consisting of 40 % (g g<sup>−1</sup>) Poly Methyl Methacrylate (PMMA) and 60 % (g g<sup>−1</sup>) aluminium hydroxide <span><math><mrow><mtext>Al(OH)3</mtext></mrow></math></span>, combines the durability and aesthetics of real marble with the lightweight and moldability of plastic. It is the most sought-after synthetic stone in the world, with a production volume of over 1 million t in 2021. However, due to a high level of cross-linking, mechanical recycling of the composite is impossible, while chemical recycling is achievable, yet unprofitable. The only economically viable recycling solution is to retain the value of both the organic and inorganic fraction of the composite. We investigated the pyrolysis and hydrolysis of post-consumer end-of-life artificial marble to identify possible valorization routes, examining the effects of temperature, water content, catalyst presence, and heating style. Temperature directly accelerates thermolysis, and indirectly hydrolysis. The water inherently present in <span><math><mrow><mtext>Al(OH)3</mtext></mrow></math></span> drives initial hydrolysis, and temperature expedites inorganic fraction dehydration, increasing local water partial pressure near polymer ester sites. Above 350<!--> <!-->°C, PMMAeq depolymerizes faster than it hydrolyzes, balancing the effects of temperature on water dehydration with the depletion of available ester sites for hydrolysis. Contrary to intuition, PMMA does not depolymerize to its monomer MMA and then hydrolyze its acid (methacrylic acid); instead, PMMA partially hydrolyzes to poly methacrylic acid (PMAA) while also depolymerizing to MMA. PMAA then dehydrates and degrades, releasing CO and CO<sub>2</sub>. The optimal method involves a heating ramp that first releases water at 300<!--> <!-->°C, minimizing hydrolysis, and then favors MMA production at 400<!--> <!-->°C, achieving a 66 % (g g<sup>−1</sup>) MMA yield. Regardless of the operative conditions, the inorganic fraction transforms from <span><math><mrow><mtext>Al(OH)3</mtext></mrow></math></span> to a <span><math><mi>γ</mi></math></span>-alumina precursor, boehmite. Additionally, the remaining polymer in the residue, about 9 % (g g<sup>−1</sup>), has the required heat capacity for an energy-self sufficient calcination to <span><math><mi>γ</mi></math></span>-alumina. This dual-phase process not only maximizes MMA recovery but also retains the value of the inorganic fraction, providing a sustainable and economically viable recycling method for artificial marble.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"195 ","pages":"Pages 129-144"},"PeriodicalIF":7.1,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143337953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-06DOI: 10.1016/j.wasman.2025.01.039
Binaya Sapkota, Agamutu Pariatamby
Although healthcare waste management (HCWM) legislations prevail in Association of Southeast Asian Nations (ASEAN), there appears a prominent gap in standalone pharmaceutical waste management (PWM) legislation making harmonization of PWM challenging in the region. This review is aimed to comprehensively overview the PWM-related legislations in ASEAN, comprising of 10 economically rising countries in Southeast Asia. The relevant regulatory documents, that were promulgated till August 31, 2024 and that were in English or officially translated in English, were extracted from PubMed/Medline, Scopus, Science Direct, Google Scholar, and respective country’s government websites. The documents were considered suitable based on their relevance, accessibility, and timeliness. The policy analysis revealed that all Member States in ASEAN lack specific legislations on PWM, and are managing pharmaceutical waste (PW) within the umbrella legislation of HCWM or biomedical waste management. The review discussed implications of joint ASEAN legislations, relevant guiding principles of waste management, and international guidelines relevant to PWM such as Basel Convention, Stockholm Convention, and the status of their endorsement in ASEAN. Some ASEAN countries such as Indonesia, Malaysia, Philippines, Singapore, Thailand and Vietnam have established infrastructures and regulatory setup for HCWM but still lack specific PWM legislations. ASEAN can foster harmonized legislative frameworks, facilities and technologies in PWM, raising public awareness and active participation to mitigate PW problem. The hard laws such as Acts, regulations, and ordinances are definitely aimed for PWM in ASEAN, but at least harmonized soft laws in the form of guidelines are imperative to harmonize PWM practice.
{"title":"Pharmaceutical waste management legislations: Where do ASEAN countries stand in harmonization? A review of regulatory documents","authors":"Binaya Sapkota, Agamutu Pariatamby","doi":"10.1016/j.wasman.2025.01.039","DOIUrl":"10.1016/j.wasman.2025.01.039","url":null,"abstract":"<div><div>Although healthcare waste management (HCWM) legislations prevail in Association of Southeast Asian Nations (ASEAN), there appears a prominent gap in standalone pharmaceutical waste management (PWM) legislation making harmonization of PWM challenging in the region. This review is aimed to comprehensively overview the PWM-related legislations in ASEAN, comprising of 10 economically rising countries in Southeast Asia. The relevant regulatory documents, that were promulgated till August 31, 2024 and that were in English or officially translated in English, were extracted from PubMed/Medline, Scopus, Science Direct, Google Scholar, and respective country’s government websites. The documents were considered suitable based on their relevance, accessibility, and timeliness. The policy analysis revealed that all Member States in ASEAN lack specific legislations on PWM, and are managing pharmaceutical waste (PW) within the umbrella legislation of HCWM or biomedical waste management. The review discussed implications of joint ASEAN legislations, relevant guiding principles of waste management, and international guidelines relevant to PWM such as Basel Convention, Stockholm Convention, and the status of their endorsement in ASEAN. Some ASEAN countries such as Indonesia, Malaysia, Philippines, Singapore, Thailand and Vietnam have established infrastructures and regulatory setup for HCWM but still lack specific PWM legislations. ASEAN can foster harmonized legislative frameworks, facilities and technologies in PWM, raising public awareness and active participation to mitigate PW problem. The hard laws such as Acts, regulations, and ordinances are definitely aimed for PWM in ASEAN, but at least harmonized soft laws in the form of guidelines are imperative to harmonize PWM practice.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"195 ","pages":""},"PeriodicalIF":7.1,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-04DOI: 10.1016/j.wasman.2025.01.026
Hongyong Fan , Olusegun K. Abass , Chaoxiang Liu , Chenghao Li , Yingjie Sun , Huawei Wang , Wushan Chen
Regulation of labile fraction of excreted manure represents a promising advance for environmental pollution mitigation. However, investigation of the properties of various pollutant fractions within manure and potential influence of dietary nutrient fractions on the release of labile manure remains unclear. Feeding trials involving pigs at three distinct growth stages fed by diets with nine different energy levels were conducted and the characteristics of labile manure generated under various treatments based on nutrient profiles were analyzed. The impact of dietary nutrient fractions on variables such as labile manure pollutants, pig performance, manure weight and dominant microorganisms were evaluated via theoretical modeling and correlation analysis. The results indicated that critical dietary nutrient factors such as dietary C fraction, protein N-materials and dietary P fraction varied respectively with pig growth stages. The labile manure composition and proportion were influenced by dietary C/N/P fractions and indigestible components, through regulation of the structure of the gut microbiota and the relative abundance of gut microbes. This study finds that initiating dietary regulatory measures could effectively control the release of labile manure and reduce its proportion in the overall manure and thus, provides a novel approach to achieve manure source pollution control, ensure environmental-friendly diet formula and mitigate manure-related environmental pollution.
{"title":"Impact of C/N/P dietary nutrient on manure characteristics: Pollutant fractions and microbial community","authors":"Hongyong Fan , Olusegun K. Abass , Chaoxiang Liu , Chenghao Li , Yingjie Sun , Huawei Wang , Wushan Chen","doi":"10.1016/j.wasman.2025.01.026","DOIUrl":"10.1016/j.wasman.2025.01.026","url":null,"abstract":"<div><div>Regulation of labile fraction of excreted manure represents a promising advance for environmental pollution mitigation. However, investigation of the properties of various pollutant fractions within manure and potential influence of dietary nutrient fractions on the release of labile manure remains unclear. Feeding trials involving pigs at three distinct growth stages fed by diets with nine different energy levels were conducted and the characteristics of labile manure generated under various treatments based on nutrient profiles were analyzed. The impact of dietary nutrient fractions on variables such as labile manure pollutants, pig performance, manure weight and dominant microorganisms were evaluated via theoretical modeling and correlation analysis. The results indicated that critical dietary nutrient factors such as dietary C fraction, protein N-materials and dietary P fraction varied respectively with pig growth stages. The labile manure composition and proportion were influenced by dietary C/N/P fractions and indigestible components, through regulation of the structure of the gut microbiota and the relative abundance of gut microbes. This study finds that initiating dietary regulatory measures could effectively control the release of labile manure and reduce its proportion in the overall manure and thus, provides a novel approach to achieve manure source pollution control, ensure environmental-friendly diet formula and mitigate manure-related environmental pollution.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"194 ","pages":"Pages 401-413"},"PeriodicalIF":7.1,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143150336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-03DOI: 10.1016/j.wasman.2025.01.041
Mrunal S. Bokade, Surender Singh, Devendra Narain Singh
We read with great interest the paper by Xie et al. (2024) that describes the methodology for recycling and reusing microplastics, MPs, by utilizing it into the geopolymer, GP, matrix made from fly ash, FA, and ground granulated blast furnace slag, GGBFS. The GP was created by activating the FA and GGBFS (7:3 ratio) using 16 M NaOH. Herein the MPs of various sizes (viz. 50, 150, and 500 µm) and varying percentages (viz. 2.5, 5, 7.5, and 10) were encapsulated in the GP matrix and further, they were cured at 40 and 80 ˚C for 24 h and later at ambient temperatures. Several experiments were performed to investigate the physical (viz. bulk density, fluidity, thermal resistance), mechanical (viz. compressive strength, flexural strength), mineralogical, and microstructural properties of synthesized GP. Furthermore, these samples were exposed to elevated temperatures viz. 200, 400, and 600 ˚C to investigate the effect of MPs on the thermal resistance of GP matrix. Although, Xie et al. (2024) have presented some intriguing findings, however there are serious issues concerning the proposed ideology and subsequently, its justification, which the authors would like to highlight through this discussion.
{"title":"Discussion on “Potential improvement in the mechanical performance and thermal resistance of geopolymer with appropriate microplastic incorporation: A sustainable solution for recycling and reusing microplastics”","authors":"Mrunal S. Bokade, Surender Singh, Devendra Narain Singh","doi":"10.1016/j.wasman.2025.01.041","DOIUrl":"10.1016/j.wasman.2025.01.041","url":null,"abstract":"<div><div>We read with great interest the paper by <span><span>Xie et al. (2024)</span></span> that describes the methodology for recycling and reusing microplastics, <em>MP</em>s, by utilizing it into the geopolymer, <em>GP</em>, matrix made from fly ash, <em>FA</em>, and ground granulated blast furnace slag, <em>GGBFS</em>. The <em>GP</em> was created by activating the <em>FA</em> and <em>GGBFS</em> (7:3 ratio) using 16 M NaOH. Herein the <em>MPs</em> of various sizes (viz. 50, 150, and 500 µm) and varying percentages (viz. 2.5, 5, 7.5, and 10) were encapsulated in the <em>GP</em> matrix and further, they were cured at 40 and 80 <sup>˚</sup>C for 24 h and later at ambient temperatures. Several experiments were performed to investigate the physical (viz. bulk density, fluidity, thermal resistance), mechanical (viz. compressive strength, flexural strength), mineralogical, and microstructural properties of synthesized <em>GP</em>. Furthermore, these samples were exposed to elevated temperatures viz. 200, 400, and 600 <sup>˚</sup>C to investigate the effect of <em>MP</em>s on the thermal resistance of <em>GP</em> matrix. Although, <span><span>Xie et al. (2024)</span></span> have presented some intriguing findings, however there are serious issues concerning the proposed ideology and subsequently, its justification, which the authors would like to highlight through this discussion.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"195 ","pages":"Pages 104-106"},"PeriodicalIF":7.1,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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