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}
Pub Date : 2025-02-02DOI: 10.1016/j.wasman.2025.01.038
Chengjie Xue , Yifu Peng , Zhanqiang Fang , Peichun Lu , Junyao Yang
Biomass has been utilized in the carbothermal reduction method to reduce iron cations, thereby synthesizing nano zero-valent iron (nZVI). The effect of the biomass components on the regulation of the performance of prepared nZVI is not clear and the mechanism of action remains to be explored. Biomass components such as cellulose, hemicellulose, lignin, and amylum were used to prepare carbon-loaded nano zero-valent iron. It was demonstrated that increasing the cellulose content of the mixture led to higher Fe0 content by 2–6 times and a greater activation efficiency of peroxydisulfate (PDS) by 2–5 times. nZVI prepared by carbothermal reduction using bagasse (Fe0/CB) removed 99.8 % of metronidazole in 60 min. The bagasse’s cellulose content was found to be 59.5 % and the results demonstrated that the composites prepared with the cellulose content exceeded 60 % had unusual properties. The pyrolysis process of the mixtures showed that cellulose promotes the production of nZVI by generating more reducing gases (e.g. CO, CH4). Furthermore, the efficiency of activated PDS in removing metronidazole was confirmed, with cellulose-prepared nZVI (c-Fe0/C) proving to be the most effective activator. Its removal rate was 1.3 times higher than that of Fe0/CB. Physical characterization and mechanistic investigations demonstrated that c-Fe0/C has the same active sites as Fe0/CB and produces the same type and amount of reactive oxygen species. These demonstrates that cellulose is a critical component in the preparation of nZVI during carbothermal reduction. This study provides guidelines for preparing carbothermal reduced nZVI and establishes a theoretical basis for its engineering application.
{"title":"Performance of nano zero-valent iron activated peroxydisulfates prepared by carbothermal reduction using various bagasse components","authors":"Chengjie Xue , Yifu Peng , Zhanqiang Fang , Peichun Lu , Junyao Yang","doi":"10.1016/j.wasman.2025.01.038","DOIUrl":"10.1016/j.wasman.2025.01.038","url":null,"abstract":"<div><div>Biomass has been utilized in the carbothermal reduction method to reduce iron cations, thereby synthesizing nano zero-valent iron (nZVI). The effect of the biomass components on the regulation of the performance of prepared nZVI is not clear and the mechanism of action remains to be explored. Biomass components such as cellulose, hemicellulose, lignin, and amylum were used to prepare carbon-loaded nano zero-valent iron. It was demonstrated that increasing the cellulose content of the mixture led to higher Fe<sup>0</sup> content by 2–6 times and a greater activation efficiency of peroxydisulfate (PDS) by 2–5 times. nZVI prepared by carbothermal reduction using bagasse (Fe<sup>0</sup>/CB) removed 99.8 % of metronidazole in 60 min. The bagasse’s cellulose content was found to be 59.5 % and the results demonstrated that the composites prepared with the cellulose content exceeded 60 % had unusual properties. The pyrolysis process of the mixtures showed that cellulose promotes the production of nZVI by generating more reducing gases (e.g. CO, CH<sub>4</sub>). Furthermore, the efficiency of activated PDS in removing metronidazole was confirmed, with cellulose-prepared nZVI (c-Fe<sup>0</sup>/C) proving to be the most effective activator. Its removal rate was 1.3 times higher than that of Fe<sup>0</sup>/CB. Physical characterization and mechanistic investigations demonstrated that c-Fe<sup>0</sup>/C has the same active sites as Fe<sup>0</sup>/CB and produces the same type and amount of reactive oxygen species. These demonstrates that cellulose is a critical component in the preparation of nZVI during carbothermal reduction. This study provides guidelines for preparing carbothermal reduced nZVI and establishes a theoretical basis for its engineering application.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"195 ","pages":"Pages 92-103"},"PeriodicalIF":7.1,"publicationDate":"2025-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143123775","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 : 2025-02-01DOI: 10.1016/j.wasman.2024.11.039
Ana García-Rández , Luciano Orden , Evan A.N. Marks , Javier Andreu-Rodríguez , Samuel Franco-Luesma , Encarnación Martínez-Sabater , José Antonio Saéz-Tovar , María Dolores Pérez-Murcia , Enrique Agulló , María Ángeles Bustamante , Maite Cháfer , Raúl Moral
Olive mill wastes (OMW) management by composting allows to obtain valuable fertilizing products, but also implies significant fluxes of greenhouse gases (GHG). For a proper OMW composting, high C- and N co-substrates are necessary, but little is known concerning their effect on GHG emissions in OMW-industrial scale composting. In this study, different co-composting agents (cattle manure (CM), poultry manure (PM), sheep manure (SM) and pig slurry solid fraction (PSSF) as N sources and olive leaves (OLW) and urban pruning residues (UPR) as bulking agents and C sources) were used for OMW composting at industrial scale. Physico-chemical and chemical properties in the composting samples, and GHG (CO2, CH4 and N2O) fluxes were monitored in 12 industrial-scale windrows. GHG emissions were firstly influenced by N source, with the highest accumulated global warming potential (GWP) associated with PM (512 kg CO2eq pile-1), since PM composts were associated with the greatest N2O (0.33 kg pile-1) and CH4 emissions (15.67 kg pile-1). Meanwhile, PSSF was associated with the highest CO2 emissions (1113 kg pile-1). UPR as a bulking agent facilitated 10 % greater mineralization of the biomass than OLW, however this C-source was not associated with higher GHG emissions. The results showed that while mineralization dynamics may be impacted by C sources, GHG emissions were mainly conditioned by the characteristics of nutrient-heavy feedstocks (PM and SM). Moreover, manures as nitrogen-laden co-substrates had widely differing effects on total GWP, and that of individual gases, but further research is necessary to understand the mechanisms explaining such differences.
通过堆肥管理橄榄厂废物(OMW)可以获得有价值的肥料产品,但也意味着大量的温室气体(GHG)通量。高碳、高氮共基质对于合理的OMW堆肥是必要的,但它们对OMW工业规模堆肥中温室气体排放的影响知之甚少。本研究采用牛粪(CM)、禽粪(PM)、羊粪(SM)和猪浆固体组分(PSSF)作为N源,橄榄叶(OLW)和城市修剪残渣(UPR)作为膨化剂和C源,在工业规模上进行了OMW堆肥。在12个工业尺度窗口中监测了堆肥样品的物理化学和化学性质以及温室气体(CO2, CH4和N2O)通量。温室气体排放首先受到N源的影响,累积全球变暖潜势(GWP)与PM相关(512 kg CO2eq pile-1)最高,因为PM堆肥与最大的N2O (0.33 kg pile-1)和CH4 (15.67 kg pile-1)相关。同时,PSSF与最高的CO2排放量(1113 kg桩-1)相关。UPR作为膨胀剂比OLW促进了10%的生物质矿化,但这种碳源与更高的温室气体排放无关。结果表明,矿化动态受碳源影响,而温室气体排放主要受重养分原料(PM和SM)的影响。此外,作为含氮共基质的肥料对总GWP和单个气体的影响差异很大,但需要进一步研究以了解解释这种差异的机制。
{"title":"Monitoring of greenhouse gas emissions and compost quality during olive mill waste co-composting at industrial scale: The effect of N and C sources","authors":"Ana García-Rández , Luciano Orden , Evan A.N. Marks , Javier Andreu-Rodríguez , Samuel Franco-Luesma , Encarnación Martínez-Sabater , José Antonio Saéz-Tovar , María Dolores Pérez-Murcia , Enrique Agulló , María Ángeles Bustamante , Maite Cháfer , Raúl Moral","doi":"10.1016/j.wasman.2024.11.039","DOIUrl":"10.1016/j.wasman.2024.11.039","url":null,"abstract":"<div><div>Olive mill wastes (OMW) management by composting allows to obtain valuable fertilizing products, but also implies significant fluxes of greenhouse gases (GHG). For a proper OMW composting, high C- and N co-substrates are necessary, but little is known concerning their effect on GHG emissions in OMW-industrial scale composting. In this study, different co-composting agents (cattle manure (CM), poultry manure (PM), sheep manure (SM) and pig slurry solid fraction (PSSF) as N sources and olive leaves (OLW) and urban pruning residues (UPR) as bulking agents and C sources) were used for OMW composting at industrial scale. Physico-chemical and chemical properties in the composting samples, and GHG (CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O) fluxes were monitored in 12 industrial-scale windrows. GHG emissions were firstly influenced by N source, with the highest accumulated global warming potential (GWP) associated with PM (512 kg CO<sub>2</sub>eq pile<sup>-1</sup>), since PM composts were associated with the greatest N<sub>2</sub>O (0.33 kg pile<sup>-1</sup>) and CH<sub>4</sub> emissions (15.67 kg pile<sup>-1</sup>). Meanwhile, PSSF was associated with the highest CO<sub>2</sub> emissions (1113 kg pile<sup>-1</sup>). UPR as a bulking agent facilitated 10 % greater mineralization of the biomass than OLW, however this C-source was not associated with higher GHG emissions. The results showed that while mineralization dynamics may be impacted by C sources, GHG emissions were mainly conditioned by the characteristics of nutrient-heavy feedstocks (PM and SM). Moreover, manures as nitrogen-laden co-substrates had widely differing effects on total GWP, and that of individual gases, but further research is necessary to understand the mechanisms explaining such differences.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"193 ","pages":"Pages 33-43"},"PeriodicalIF":7.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142787328","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 : 2025-02-01DOI: 10.1016/j.wasman.2024.12.003
Stavros A. Theofanidis , Evangelos Delikonstantis , Vasileia-Loukia Yfanti , Vladimir V. Galvita , Angeliki A. Lemonidou , Kevin Van Geem
In contemporary times, global plastic waste production has doubled in comparison to two decades ago, with only 9% effectively recycled. The polymer industry is undergoing a transition to address the disparity between plastic production and end-of-life waste management. Chemical recycling offers a solution by converting plastic waste into its constituent building blocks, or monomers, which can be utilized in the production of new, high-quality plastics. This concise review provides an overview of conventional chemical recycling technologies employing heated reactors, before delving into ongoing efforts towards electrifying the chemical recycling process. A conceptual framework for a fully electrified value chain aimed at achieving plastics circularity is outlined and analyzed. Additionally, attention is given to the challenges posed by industry inertia towards adopting electrified technologies, as well as performance issues stemming from the intermittent nature of renewable energy sources and the availability of long-duration renewable electricity storage options.
{"title":"An electricity-powered future for mixed plastic waste chemical recycling","authors":"Stavros A. Theofanidis , Evangelos Delikonstantis , Vasileia-Loukia Yfanti , Vladimir V. Galvita , Angeliki A. Lemonidou , Kevin Van Geem","doi":"10.1016/j.wasman.2024.12.003","DOIUrl":"10.1016/j.wasman.2024.12.003","url":null,"abstract":"<div><div>In contemporary times, global plastic waste production has doubled in comparison to two decades ago, with only 9% effectively recycled. The polymer industry is undergoing a transition to address the disparity between plastic production and end-of-life waste management. Chemical recycling offers a solution by converting plastic waste into its constituent building blocks, or monomers, which can be utilized in the production of new, high-quality plastics. This concise review provides an overview of conventional chemical recycling technologies employing heated reactors, before delving into ongoing efforts towards electrifying the chemical recycling process. A conceptual framework for a fully electrified value chain aimed at achieving plastics circularity is outlined and analyzed. Additionally, attention is given to the challenges posed by industry inertia towards adopting electrified technologies, as well as performance issues stemming from the intermittent nature of renewable energy sources and the availability of long-duration renewable electricity storage options.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"193 ","pages":"Pages 155-170"},"PeriodicalIF":7.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142814477","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 : 2025-02-01DOI: 10.1016/j.wasman.2024.12.012
Maohui Wang , Zhanfu Yong
The world’s three leading tire manufacturers have proposed specific timelines for using recycled materials. For instance, Michelin targets an increase in the proportion of sustainable materials in tires to 40 % by 2030 and aims to produce 100 % of its tires from bio-based, renewable, or recyclable materials as of 2050. In such a context, this study introduced wet mixing technology to apply recycled rubber (RR) in highly wear-resistant tire tread compounds. This technique leverages the rubber’s inherent crosslink density to enhance the mechanical performance of final products. The results indicated that wet mixing effectively addressed the high viscosity issue of RR. In the traditional dry mixing method, physical blending typically results in large particle sizes and suboptimal performance. In contrast, wet mixing reduced the rubber’s hysteresis loss by 75 % and improved its rebound performance by 35.6 % at 23 °C, 60 °C, and 100 °C compared to traditional dry mixing. DIN volume abrasion was also reduced by 23.3 %. Remarkably, Akron abrasion nearly doubled its effect. Additionally, wet mixing regulated aggregate structure and formed a densely packed honeycomb-like structure within RR. Incorporating RR using wet mixing demonstrates noticeable advantages in carbon black/natural rubber/RR composite materials. This approach also presents a viable path to sustainable development in the rubber manufacturing industry.
{"title":"Enhancing the sustainability of rubber materials: Dual benefits of wet mixing technology and recycled rubber’s honeycomb reinforcement structure","authors":"Maohui Wang , Zhanfu Yong","doi":"10.1016/j.wasman.2024.12.012","DOIUrl":"10.1016/j.wasman.2024.12.012","url":null,"abstract":"<div><div>The world’s three leading tire manufacturers have proposed specific timelines for using recycled materials. For instance, Michelin targets an increase in the proportion of sustainable materials in tires to 40 % by 2030 and aims to produce 100 % of its tires from bio-based, renewable, or recyclable materials as of 2050. In such a context, this study introduced wet mixing technology to apply recycled rubber (RR) in highly wear-resistant tire tread compounds. This technique leverages the rubber’s inherent crosslink density to enhance the mechanical performance of final products. The results indicated that wet mixing effectively addressed the high viscosity issue of RR. In the traditional dry mixing method, physical blending typically results in large particle sizes and suboptimal performance. In contrast, wet mixing reduced the rubber’s hysteresis loss by 75 % and improved its rebound performance by 35.6 % at 23 °C, 60 °C, and 100 °C compared to traditional dry mixing. DIN volume abrasion was also reduced by 23.3 %. Remarkably, Akron abrasion nearly doubled its effect. Additionally, wet mixing regulated aggregate structure and formed a densely packed honeycomb-like structure within RR. Incorporating RR using wet mixing demonstrates noticeable advantages in carbon black/natural rubber/RR composite materials. This approach also presents a viable path to sustainable development in the rubber manufacturing industry.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"193 ","pages":"Pages 190-198"},"PeriodicalIF":7.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142822215","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 : 2025-02-01DOI: 10.1016/j.wasman.2024.12.002
Joshua T. Grassel , Adolfo R. Escobedo , Rajesh Buch
The primary goals of this paper are to facilitate data-driven decision making in solid waste management (SWM) and to support the transition towards a circular economy, by providing estimates of the composition and quantity of waste. To that end, it introduces a novel two-phase strategy for predicting municipal solid waste (MSW). The first phase predicts the waste composition, the second phase predicts the total quantity, and the two predictions are combined to give a comprehensive waste estimate. This novel approach overcomes limitations of existing methods that rely on material-specific quantity data, facilitating the prediction of dozens of waste material streams; existing methods typically classify MSW into no more than 10 categories, and often reduce it to a single aggregate total. To implement this strategy, the proposed study utilizes publicly available data encompassing demographic, economic, and spatial predictors, in conjunction with waste sampling reports. In addition, it develops a Least Absolute Shrinkage and Selection Operator (LASSO) regression model to estimate the MSW composition across 43 comprehensive material categories. The LASSO model is designed to predict MSW composition distinctly from quantity. The model’s capability is demonstrated through case studies, showcasing its potential to provide detailed waste estimates at the U.S. county level.
{"title":"Predicting the composition of solid waste at the county scale","authors":"Joshua T. Grassel , Adolfo R. Escobedo , Rajesh Buch","doi":"10.1016/j.wasman.2024.12.002","DOIUrl":"10.1016/j.wasman.2024.12.002","url":null,"abstract":"<div><div>The primary goals of this paper are to facilitate data-driven decision making in solid waste management (SWM) and to support the transition towards a circular economy, by providing estimates of the composition and quantity of waste. To that end, it introduces a novel two-phase strategy for predicting municipal solid waste (MSW). The first phase predicts the waste composition, the second phase predicts the total quantity, and the two predictions are combined to give a comprehensive waste estimate. This novel approach overcomes limitations of existing methods that rely on material-specific quantity data, facilitating the prediction of dozens of waste material streams; existing methods typically classify MSW into no more than 10 categories, and often reduce it to a single aggregate total. To implement this strategy, the proposed study utilizes publicly available data encompassing demographic, economic, and spatial predictors, in conjunction with waste sampling reports. In addition, it develops a Least Absolute Shrinkage and Selection Operator (LASSO) regression model to estimate the MSW composition across 43 comprehensive material categories. The LASSO model is designed to predict MSW composition distinctly from quantity. The model’s capability is demonstrated through case studies, showcasing its potential to provide detailed waste estimates at the U.S. county level.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"193 ","pages":"Pages 293-306"},"PeriodicalIF":7.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142855337","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 : 2025-02-01DOI: 10.1016/j.wasman.2024.12.013
A.S. Varling, V. Chrysochoidis, V. Bisinella, B. Valverde-Pérez, T.H. Christensen
The liquid fraction of digestate (LFD) from anaerobic digestion of food waste contains high nitrogen concentrations, and in some countries, the LFD is treated as wastewater. We modelled alternative LFD treatments, including pretreatment with the partial nitritation Anammox (PNA) process. The PNA effluent is discharged to the sewers to undergo further treatment by conventional nitrification and (post- or pre-) denitrification. Life-cycle inventories were developed for the LFD treatment alternatives, including N2O emissions and electricity consumption estimates. The climate change (CC) impact was estimated using life cycle assessment in three different energy systems ranging from fossil-based to fully renewable. In the fossil energy system, pretreatment with PNA was attractive, while in the more renewable energy systems, the PNA process did not improve the CC account due to high N2O emissions. Pre-denitrification is the most attractive LFD treatment technology in a fully renewable energy system. Linking the LFD treatment to the anaerobic digestion of food waste showed that LFD treatment is a significant contributor to the overall CC account. As we move towards less fossil-based electricity, the anaerobic digestion of food waste constitutes a CC load of 350–450 kg CO2-eq/tonne biowaste, of which up to a third can be attributed to the LFD treatment. The N2O emissions are the main contributor, constituting up to 50 % in a fossil-based energy system and even higher in a renewable energy system. We conclude that the LFD treatment must be addressed in assessing anaerobic digestion when the LFD is discharged to the sewer. Our study also points to the need to find alternative ways of managing the LFD.
{"title":"Climate change impacts of biological treatment of liquid digestate from the anaerobic digestion of food waste","authors":"A.S. Varling, V. Chrysochoidis, V. Bisinella, B. Valverde-Pérez, T.H. Christensen","doi":"10.1016/j.wasman.2024.12.013","DOIUrl":"10.1016/j.wasman.2024.12.013","url":null,"abstract":"<div><div>The liquid fraction of digestate (LFD) from anaerobic digestion of food waste contains high nitrogen concentrations, and in some countries, the LFD is treated as wastewater. We modelled alternative LFD treatments, including pretreatment with the partial nitritation Anammox (PNA) process. The PNA effluent is discharged to the sewers to undergo further treatment by conventional nitrification and (post- or pre-) denitrification. Life-cycle inventories were developed for the LFD treatment alternatives, including N<sub>2</sub>O emissions and electricity consumption estimates. The climate change (CC) impact was estimated using life cycle assessment in three different energy systems ranging from fossil-based to fully renewable. In the fossil energy system, pretreatment with PNA was attractive, while in the more renewable energy systems, the PNA process did not improve the CC account due to high N<sub>2</sub>O emissions. Pre-denitrification is the most attractive LFD treatment technology in a fully renewable energy system. Linking the LFD treatment to the anaerobic digestion of food waste showed that LFD treatment is a significant contributor to the overall CC account. As we move towards less fossil-based electricity, the anaerobic digestion of food waste constitutes a CC load of 350–450 kg CO<sub>2</sub>-eq/tonne biowaste, of which up to a third can be attributed to the LFD treatment. The N<sub>2</sub>O emissions are the main contributor, constituting up to 50 % in a fossil-based energy system and even higher in a renewable energy system. We conclude that the LFD treatment must be addressed in assessing anaerobic digestion when the LFD is discharged to the sewer. Our study also points to the need to find alternative ways of managing the LFD.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"193 ","pages":"Pages 339-349"},"PeriodicalIF":7.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142865561","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 : 2025-02-01DOI: 10.1016/j.wasman.2024.12.020
Jonathan Cohen, Jorge Gil, Leonardo Rosado
Managing the diverse waste fractions generated by households presents a significant environmental and logistical challenge. One widely adopted solution is waste sorting at the source, where residents are required to separate their waste into designated containers. The success of this strategy depends on the extent of adoption and the behaviour of residents. Waste separation is a complex activity influenced by various interrelated factors. While the Theory of Planned Behaviour (TPB) has been effectively applied to characterise waste-sorting behaviour, it primarily focuses on internal psychological mechanisms, often overlooking environmental factors such as the placement of waste bins or the condition of sorting stations—critical elements for spatial planning. To bridge this gap, this study presents an agent-based model (ABM) that simulates residential waste sorting in urban scenarios, incorporating TPB for the agents’ behavioural architecture (residents). Three features distinguish this ABM from previous efforts: (i) Agents in the model are residents and not aggregated households, allowing for a one-to-one integration with TPB; (ii) the ABM bridges the gap between individual waste sorting behaviour extracted by TPB and outcomes quantifiable through waste sorting metrics; and (iii) the ABM is spatially explicit, enabling the exploration of various urban scenarios.
The ABM was applied to two urban areas with differing population densities, demonstrating that changes in bin placement impacts sorting behaviour, and proximity to recyclable waste bins influences the correct sorting of residual waste. This study illustrates how modelling the interaction between the urban environment and waste sorting behaviour can reveal the impact of individual residents’ actions on overall waste sorting performance.
{"title":"Exploring urban scenarios of individual residential waste sorting using a spatially explicit agent-based model","authors":"Jonathan Cohen, Jorge Gil, Leonardo Rosado","doi":"10.1016/j.wasman.2024.12.020","DOIUrl":"10.1016/j.wasman.2024.12.020","url":null,"abstract":"<div><div>Managing the diverse waste fractions generated by households presents a significant environmental and logistical challenge. One widely adopted solution is waste sorting at the source, where residents are required to separate their waste into designated containers. The success of this strategy depends on the extent of adoption and the behaviour of residents. Waste separation is a complex activity influenced by various interrelated factors. While the Theory of Planned Behaviour (TPB) has been effectively applied to characterise waste-sorting behaviour, it primarily focuses on internal psychological mechanisms, often overlooking environmental factors such as the placement of waste bins or the condition of sorting stations—critical elements for spatial planning. To bridge this gap, this study presents an agent-based model (ABM) that simulates residential waste sorting in urban scenarios, incorporating TPB for the agents’ behavioural architecture (residents). Three features distinguish this ABM from previous efforts: (i) Agents in the model are residents and not aggregated households, allowing for a one-to-one integration with TPB; (ii) the ABM bridges the gap between individual waste sorting behaviour extracted by TPB and outcomes quantifiable through waste sorting metrics; and (iii) the ABM is spatially explicit, enabling the exploration of various urban scenarios.</div><div>The ABM was applied to two urban areas with differing population densities, demonstrating that changes in bin placement impacts sorting behaviour, and proximity to recyclable waste bins influences the correct sorting of residual waste. This study illustrates how modelling the interaction between the urban environment and waste sorting behaviour can reveal the impact of individual residents’ actions on overall waste sorting performance.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"193 ","pages":"Pages 350-362"},"PeriodicalIF":7.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142865566","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}
Monitoring campaigns to collect and characterize urban park litter have been carried out in Italy annually from 2018 to 2023. A total of 274 urban parks in 108 cities (with 745 inhabitants to 2.7 million) were monitored. The citizen science approach was applied, and each campaign involved yearly an average of 416 volunteers coordinated by Legambiente. An adaptation of the sampling protocol proposed by the Marine Strategy Framework Directive (MSFD) Technical Group on Marine Litter (2008/56/CE) was applied. In total 161,293 (mean value 26,882.2 ± 4,743.4) items were collected within 42,300 m2 (density 3.82 items/m2). Cigarette butts are the most widespread waste: 36.3 % ± 5.5 % and up to 25 butts/m2 were found. Significant amounts of metal (16.2 %), glass/ceramics (13.0 %) and paper/cardboard (10.7 %) were found. Despite the COVID emergency having ended in 2021, during the 2022 monitoring campaign face masks only represent 0.2 % of the total waste items. No correlation was found between the amount of waste and the number of inhabitants or the geographical position of the city. The population density was poorly correlated with the quantity of waste collected while a slight correlation was evidenced by the presence of plastic bottles which seem to have decreased in recent years. Using the FTIR Spectroscopy 19 different polymers were identified. The most common were cellulose acetate (cigarette butts) polyethylene and polypropylene. Following the application of recent SUP regulations, polylactic acid and starch blended biopolymers were found (till 0.3 %). Finally, the presence of highly degraded polymers was observed.
{"title":"Characterization of urban park litter pollution","authors":"Loris Pietrelli , Stefania Di Vito , Elisabetta Lacolla , Antonella Piozzi , Elisa Scocchera","doi":"10.1016/j.wasman.2024.11.047","DOIUrl":"10.1016/j.wasman.2024.11.047","url":null,"abstract":"<div><div>Monitoring campaigns to collect and characterize urban park litter have been carried out in Italy annually from 2018 to 2023. A total of 274 urban parks in 108 cities (with 745 inhabitants to 2.7 million) were monitored. The citizen science approach was applied, and each campaign involved yearly an average of 416 volunteers coordinated by Legambiente. An adaptation of the sampling protocol proposed by the Marine Strategy Framework Directive (MSFD) Technical Group on Marine Litter (2008/56/CE) was applied. In total 161,293 (mean value 26,882.2 ± 4,743.4) items were collected within 42,300 m<sup>2</sup> (density 3.82 items/m<sup>2</sup>). Cigarette butts are the most widespread waste: 36.3 % ± 5.5 % and up to 25 butts/m<sup>2</sup> were found. Significant amounts of metal (16.2 %), glass/ceramics (13.0 %) and paper/cardboard (10.7 %) were found. Despite the COVID emergency having ended in 2021, during the 2022 monitoring campaign face masks only represent 0.2 % of the total waste items. No correlation was found between the amount of waste and the number of inhabitants or the geographical position of the city. The population density was poorly correlated with the quantity of waste collected while a slight correlation was evidenced by the presence of plastic bottles which seem to have decreased in recent years. Using the FTIR Spectroscopy 19 different polymers were identified. The most common were cellulose acetate (cigarette butts) polyethylene and polypropylene. Following the application of recent SUP regulations, polylactic acid and starch blended biopolymers were found (till 0.3 %). Finally, the presence of highly degraded polymers was observed.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"193 ","pages":"Pages 95-104"},"PeriodicalIF":7.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142792439","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 : 2025-02-01DOI: 10.1016/j.wasman.2024.12.039
Qing Yue, Jia Wen, Yichen Zhou, Yuling Zheng
With the exponential growth of global photovoltaic (PV) installed capacity, the quantity of discarded PV modules continues to rise. This study innovatively explored the sustainable recovery and utilization of raw materials from discarded solar panels, focusing on the transformation of recycled silicon into microporous silica nanoparticles (MSN). Low toxic organic solvent ethyl acetate (EA) was for the first time utilized to reduce the viscosity of ethylene–vinyl acetate (EVA) and facilitated its removal. A simple combination of nitric acid (HNO3) and sodium hydroxide (NaOH) at low temperatures (225 min HNO3 etching at room temperature followed by 40 min NaOH etching at 70 °C) completely removed the deep blue anti-reflective coating SiNx and successfully removed metallic impurities such as silver (Ag), aluminum (Al). Removal efficiencies for Ag and Al electrodes both reached 99 %, with recovery rates of 92 % and 99 % for Ag and Al, respectively. The recycled Ag and Si had a purity of 99 % and 93.2 %, respectively. The recycled pure Si was then dissolved in a NaOH solution to prepare a sodium silicate (Na2SiO3) solution. Under acidic conditions, the non-ionic surfactant Triton X-100 and cationic surfactant cetyltrimethylammonium bromide (CTAB) were used to transform the Na2SiO3 solution to the MSN. The specific surface area of the MSN measured by BET was 855.30 m2/g, with a pore size of 1.85 nm and a pore volume of 0.3963 cm3/g. This study highlights the innovative utilization of recovered silicon to fabricate advanced microporous materials, paving the way for high-value applications and promoting a sustainable photovoltaic industry.
{"title":"Resource utilization of waste solar photovoltaic panels for preparation of microporous silicon nanoparticles","authors":"Qing Yue, Jia Wen, Yichen Zhou, Yuling Zheng","doi":"10.1016/j.wasman.2024.12.039","DOIUrl":"10.1016/j.wasman.2024.12.039","url":null,"abstract":"<div><div>With the exponential growth of global photovoltaic (PV) installed capacity, the quantity of discarded PV modules continues to rise. This study innovatively explored the sustainable recovery and utilization of raw materials from discarded solar panels, focusing on the transformation of recycled silicon into microporous silica nanoparticles (MSN). Low toxic organic solvent ethyl acetate (EA) was for the first time utilized to reduce the viscosity of ethylene–vinyl acetate (EVA) and facilitated its removal. A simple combination of nitric acid (HNO<sub>3</sub>) and sodium hydroxide (NaOH) at low temperatures (225 min HNO<sub>3</sub> etching at room temperature followed by 40 min NaOH etching at 70 °C) completely removed the deep blue anti-reflective coating SiN<sub>x</sub> and successfully removed metallic impurities such as silver (Ag), aluminum (Al). Removal efficiencies for Ag and Al electrodes both reached 99 %, with recovery rates of 92 % and 99 % for Ag and Al, respectively. The recycled Ag and Si had a purity of 99 % and 93.2 %, respectively. The recycled pure Si was then dissolved in a NaOH solution to prepare a sodium silicate (Na<sub>2</sub>SiO<sub>3</sub>) solution. Under acidic conditions, the non-ionic surfactant Triton X-100 and cationic surfactant cetyltrimethylammonium bromide (CTAB) were used to transform the Na<sub>2</sub>SiO<sub>3</sub> solution to the MSN. The specific surface area of the MSN measured by BET was 855.30 m<sup>2</sup>/g, with a pore size of 1.85 nm and a pore volume of 0.3963 cm<sup>3</sup>/g. This study highlights the innovative utilization of recovered silicon to fabricate advanced microporous materials, paving the way for high-value applications and promoting a sustainable photovoltaic industry.</div></div>","PeriodicalId":23969,"journal":{"name":"Waste management","volume":"193 ","pages":"Pages 495-505"},"PeriodicalIF":7.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142910940","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}