Pub Date : 2025-09-24DOI: 10.1016/j.clet.2025.101082
Reza Shahin , Maxim A. Dulebenets
Recent studies on Vehicle Routing Problems (VRP) have substantially expanded to incorporate environmental considerations into transportation planning. Traditionally, the predominant objectives in transportation optimization revolved around reducing costs, time, or distance. However, with the increasing significance of sustainability and the management of environmental costs, logistics service providers and retailers have shifted their attention to greening their operations. In light of this, the Pollution-Routing Problem (PRP) has emerged to harmonize economic and environmental facets of transportation efforts. Despite the extensive research on the problem, there exists a notable absence of systematic reviews. As such, this review article sheds light on the evolution of the problem literature from its introduction in 2011 to 2024, reviewing 75 papers. In this study, the research on the PRP is categorized based on the taxonomy, objective function, and methodologies applied throughout the years. Finally, we pinpoint several areas of potential exploration that will serve as a blueprint for future research directions.
{"title":"From cost-centering to sustainability: A review of Pollution Routing Problems","authors":"Reza Shahin , Maxim A. Dulebenets","doi":"10.1016/j.clet.2025.101082","DOIUrl":"10.1016/j.clet.2025.101082","url":null,"abstract":"<div><div>Recent studies on Vehicle Routing Problems (VRP) have substantially expanded to incorporate environmental considerations into transportation planning. Traditionally, the predominant objectives in transportation optimization revolved around reducing costs, time, or distance. However, with the increasing significance of sustainability and the management of environmental costs, logistics service providers and retailers have shifted their attention to greening their operations. In light of this, the Pollution-Routing Problem (PRP) has emerged to harmonize economic and environmental facets of transportation efforts. Despite the extensive research on the problem, there exists a notable absence of systematic reviews. As such, this review article sheds light on the evolution of the problem literature from its introduction in 2011 to 2024, reviewing 75 papers. In this study, the research on the PRP is categorized based on the taxonomy, objective function, and methodologies applied throughout the years. Finally, we pinpoint several areas of potential exploration that will serve as a blueprint for future research directions.</div></div>","PeriodicalId":34618,"journal":{"name":"Cleaner Engineering and Technology","volume":"29 ","pages":"Article 101082"},"PeriodicalIF":6.5,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159171","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}
The construction boom of the 21st century has heightened demand for natural aggregates, leading to significant environmental degradation worldwide. On the contrary, there is a substantial generation of industrial waste and by-products like ceramic tile waste and stone dust, which are merely disposed of and stored in landfills. While both materials have the potential to be viable alternatives to natural aggregate in concrete production, their combined effects on concrete remain unexplored. This study aims to predict and optimize concrete properties incorporating stone dust (SD) and ceramic tile aggregate (CTA) as partial replacements for natural fine and coarse aggregates, respectively. Regression models were developed using response surface methodology (RSM) to assess the physical (fresh density and slump), mechanical (compressive strength, splitting tensile strength and bond strength) and durability (water absorption and carbonation depth) properties of concrete, with volumetric percentages of SD and CTA as independent variables. The analysis of variance (ANOVA) for all the desired responses indicated that the developed regression models were statistically significant in predicting the concrete properties. Based on multi-objective optimization, optimal replacement proportions of SD and CTA for enhanced concrete properties were obtained to be 30 % and 30.867 %, respectively. Hence, our findings highlight the insights of utilizing CTA and SD as viable substitutes for natural aggregate, offering a practical pathway to sustainable concrete production.
{"title":"Optimizing properties of concrete containing stone dust and ceramic tile: a response surface methodology approach","authors":"Ayesha Ferdous Mita, Miftahul Jannat Labiba, Sayeeda Rafia Maliha, Mohaiminul Haque, Sourav Ray","doi":"10.1016/j.clet.2025.101083","DOIUrl":"10.1016/j.clet.2025.101083","url":null,"abstract":"<div><div>The construction boom of the 21st century has heightened demand for natural aggregates, leading to significant environmental degradation worldwide. On the contrary, there is a substantial generation of industrial waste and by-products like ceramic tile waste and stone dust, which are merely disposed of and stored in landfills. While both materials have the potential to be viable alternatives to natural aggregate in concrete production, their combined effects on concrete remain unexplored. This study aims to predict and optimize concrete properties incorporating stone dust (SD) and ceramic tile aggregate (CTA) as partial replacements for natural fine and coarse aggregates, respectively. Regression models were developed using response surface methodology (RSM) to assess the physical (fresh density and slump), mechanical (compressive strength, splitting tensile strength and bond strength) and durability (water absorption and carbonation depth) properties of concrete, with volumetric percentages of SD and CTA as independent variables. The analysis of variance (ANOVA) for all the desired responses indicated that the developed regression models were statistically significant in predicting the concrete properties. Based on multi-objective optimization, optimal replacement proportions of SD and CTA for enhanced concrete properties were obtained to be 30 % and 30.867 %, respectively. Hence, our findings highlight the insights of utilizing CTA and SD as viable substitutes for natural aggregate, offering a practical pathway to sustainable concrete production.</div></div>","PeriodicalId":34618,"journal":{"name":"Cleaner Engineering and Technology","volume":"29 ","pages":"Article 101083"},"PeriodicalIF":6.5,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417115","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 : 2025-09-18DOI: 10.1016/j.clet.2025.101081
Fardis Nakhaei , Lana Alagha , Gary Wyss
This study investigated historical copper sulfide tailings as an unconventional source of tellurium (Te), gold (Au), and silver (Ag). Advanced analytical studies were conducted to determine the geochemical and mineralogical properties of the tailing samples. The results showed that tetradymite (Bi2Te2S) was the predominant Te-bearing mineral, while hessite (Ag2Te) was a minor Te carrier, both notably occurring within fine-grained (<8 μm) inclusions in pyrite. Gold was present as native Au, electrum (Au-Ag), and within complex silver tellurides hosted primarily in chalcopyrite and pyrite. Froth flotation studies showed that the 180 to 38 μm size range was the optimum feed size that yielded recoveries of 59 %, 37 %, and 27 % for Te, Au, and Ag, respectively. These findings suggested that froth flotation is a feasible method for concentrating Te-Au-Ag-bearing phases. Given the strong association between Te, Au, Ag, and Cu, the co-extraction of these metals should significantly enhance the economic viability of tailings’ processing.
本研究调查了历史上的硫化铜尾矿作为碲（Te）、金（Au）和银（Ag）的非常规来源。进行了深入的分析研究，确定了尾矿样品的地球化学和矿物学性质。结果表明：四长石（Bi2Te2S）是主要的含Te矿物，而半铁（Ag2Te）是次要的Te载体，两者均出现在黄铁矿的细粒（<8 μm）包裹体中。金以天然金、银（Au- ag）和主要赋存于黄铜矿和黄铁矿中的复杂碲化银的形式存在。泡沫浮选研究表明，180 ~ 38 μm为最佳给矿粒度，Te、Au和Ag的回收率分别为59%、37%和27%。研究结果表明，泡沫浮选是一种可行的富集含te - au - ag相的方法。考虑到Te、Au、Ag和Cu之间的强关联，这些金属的共萃取将显著提高尾矿处理的经济可行性。
{"title":"Unlocking the potential of copper sulfide tailings as a secondary source for tellurium and precious metals: a comprehensive characterization study","authors":"Fardis Nakhaei , Lana Alagha , Gary Wyss","doi":"10.1016/j.clet.2025.101081","DOIUrl":"10.1016/j.clet.2025.101081","url":null,"abstract":"<div><div>This study investigated historical copper sulfide tailings as an unconventional source of tellurium (Te), gold (Au), and silver (Ag). Advanced analytical studies were conducted to determine the geochemical and mineralogical properties of the tailing samples. The results showed that tetradymite (Bi2Te2S) was the predominant Te-bearing mineral, while hessite (Ag<sub>2</sub>Te) was a minor Te carrier, both notably occurring within fine-grained (<8 μm) inclusions in pyrite. Gold was present as native Au, electrum (Au-Ag), and within complex silver tellurides hosted primarily in chalcopyrite and pyrite. Froth flotation studies showed that the 180 to 38 μm size range was the optimum feed size that yielded recoveries of 59 %, 37 %, and 27 % for Te, Au, and Ag, respectively. These findings suggested that froth flotation is a feasible method for concentrating Te-Au-Ag-bearing phases. Given the strong association between Te, Au, Ag, and Cu, the co-extraction of these metals should significantly enhance the economic viability of tailings’ processing.</div></div>","PeriodicalId":34618,"journal":{"name":"Cleaner Engineering and Technology","volume":"29 ","pages":"Article 101081"},"PeriodicalIF":6.5,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145119768","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 : 2025-09-13DOI: 10.1016/j.clet.2025.101078
Asmaa A. Esmael, Naser S. Alselahi, Nayef Z. Al-Mutairi
The use of low-quality heavy fuel oil in Kuwait's thermal power plants has resulted in considerable operating inefficiencies and increased emissions of sulfur oxides (SOx), nitrogen oxides (NOx), and unburned carbon. These problems elevate maintenance costs, diminish boiler efficiency, and exacerbate environmental deterioration. This research assesses the efficacy of a water-in-oil emulsifier and a magnesium-based neutralizer in improving combustion performance and reducing emissions. Field studies were conducted in partnership with the Ministry of Electricity and Water (MEW) from 2016 to 2018 at four major power plants, with performance metrics assessed before and after treatment. The analysis included unburned carbon in fly ash, nitrogen oxides (NOx) concentrations, ash pH, free mineral acidity, and the dew point temperature of sulfuric acid.
The findings indicated that the additional treatment decreased unburned carbon by around 40 % and NOx by as much as 80 %, while concurrently reducing surplus air demands and enhancing heat exchange efficiency. Estimated fuel cost reductions ranged from 51.4 to 77.0 million USD yearly, depending upon operational circumstances. The use of additives decreased boiler fouling and corrosion, hence prolonging equipment life and reducing maintenance requirements. This research demonstrates that the application of fuel-oil additives represents a financially viable and environmentally beneficial strategy for Kuwait's thermal power industry, offering a practical pathway toward cleaner and more sustainable energy production.
{"title":"Sustainable power generation in Kuwait: Reducing pollutants and costs through innovative additive technology","authors":"Asmaa A. Esmael, Naser S. Alselahi, Nayef Z. Al-Mutairi","doi":"10.1016/j.clet.2025.101078","DOIUrl":"10.1016/j.clet.2025.101078","url":null,"abstract":"<div><div>The use of low-quality heavy fuel oil in Kuwait's thermal power plants has resulted in considerable operating inefficiencies and increased emissions of sulfur oxides (SO<sub>x</sub>), nitrogen oxides (NO<sub>x</sub>), and unburned carbon. These problems elevate maintenance costs, diminish boiler efficiency, and exacerbate environmental deterioration. This research assesses the efficacy of a water-in-oil emulsifier and a magnesium-based neutralizer in improving combustion performance and reducing emissions. Field studies were conducted in partnership with the Ministry of Electricity and Water (MEW) from 2016 to 2018 at four major power plants, with performance metrics assessed before and after treatment. The analysis included unburned carbon in fly ash, nitrogen oxides (NO<sub>x</sub>) concentrations, ash pH, free mineral acidity, and the dew point temperature of sulfuric acid.</div><div>The findings indicated that the additional treatment decreased unburned carbon by around 40 % and NO<sub>x</sub> by as much as 80 %, while concurrently reducing surplus air demands and enhancing heat exchange efficiency. Estimated fuel cost reductions ranged from 51.4 to 77.0 million USD yearly, depending upon operational circumstances. The use of additives decreased boiler fouling and corrosion, hence prolonging equipment life and reducing maintenance requirements. This research demonstrates that the application of fuel-oil additives represents a financially viable and environmentally beneficial strategy for Kuwait's thermal power industry, offering a practical pathway toward cleaner and more sustainable energy production.</div></div>","PeriodicalId":34618,"journal":{"name":"Cleaner Engineering and Technology","volume":"29 ","pages":"Article 101078"},"PeriodicalIF":6.5,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269620","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 : 2025-09-13DOI: 10.1016/j.clet.2025.101079
K. Srithar, R. Venkatesan, S. Ram Bala Ganesh, S. Leo Arockiasamy
The main aim of this study is to improve the COP of the Cold Storage system by integrating it with a HDH desalination system which produces water as a by-product. So, a conventional Cold Storage system is integrated to a novel HDH desalination system equipped with a mixed flow heat exchanger and their performance is evaluated experimentally. Water-cooled de-superheater and the mixed flow heat exchanger have been connected to the existing Cold Storage unit via refrigerant pipelines. A novel mixed flow heat exchanger with two types of air turbulators namely V – baffles and rectangular baffles were used to recover the waste heat. They have been tested experimentally to increase the heat transfer and condensation in the dehumidifier section. Air and water flow rates are varied from 682 kg/h to 2059 kg/h and from 617 kg/h to 1112 kg/h respectively. The cold storage unit is tested with five different loads of 220 W, 440 W, 660 W, 880 W and 1100 W. When air and water mass flow rates are 2059 kg/h and 617 kg/h respectively, V - baffles produced a maximum COP of 4.76 which is an increase of 18.69 % from conventional unit for a load of 220 W. At an air flow rate of 682 kg/s, the highest humidifier efficiency of 91.6 %, and maximum gain output ratio of 0.367 and recovery ratio of 0.077 are obtained.
{"title":"The Implementation of Humidification-Dehumidification Desalination system for COP enhancement in cold storage unit","authors":"K. Srithar, R. Venkatesan, S. Ram Bala Ganesh, S. Leo Arockiasamy","doi":"10.1016/j.clet.2025.101079","DOIUrl":"10.1016/j.clet.2025.101079","url":null,"abstract":"<div><div>The main aim of this study is to improve the COP of the Cold Storage system by integrating it with a HDH desalination system which produces water as a by-product. So, a conventional Cold Storage system is integrated to a novel HDH desalination system equipped with a mixed flow heat exchanger and their performance is evaluated experimentally. Water-cooled de-superheater and the mixed flow heat exchanger have been connected to the existing Cold Storage unit via refrigerant pipelines. A novel mixed flow heat exchanger with two types of air turbulators namely V – baffles and rectangular baffles were used to recover the waste heat. They have been tested experimentally to increase the heat transfer and condensation in the dehumidifier section. Air and water flow rates are varied from 682 kg/h to 2059 kg/h and from 617 kg/h to 1112 kg/h respectively. The cold storage unit is tested with five different loads of 220 W, 440 W, 660 W, 880 W and 1100 W. When air and water mass flow rates are 2059 kg/h and 617 kg/h respectively, V - baffles produced a maximum COP of 4.76 which is an increase of 18.69 % from conventional unit for a load of 220 W. At an air flow rate of 682 kg/s, the highest humidifier efficiency of 91.6 %, and maximum gain output ratio of 0.367 and recovery ratio of 0.077 are obtained.</div></div>","PeriodicalId":34618,"journal":{"name":"Cleaner Engineering and Technology","volume":"29 ","pages":"Article 101079"},"PeriodicalIF":6.5,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098081","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}
The present research assessed the performance of natural rubber latex (NRL) modified bottom ash (BA)-based geopolymer stabilized recycled concrete aggregate (RCA) as a sustainable pavement base material. Effects of NRL content (0.1, 0.2 %, and 0.3 % by weight of aggregate) and alkaline activator ratios (NaOH:Na2SiO3, G/N = 1:1, 1:1., and 1:2) in strength development and microstructure of the stabilized mixtures were evaluated. Unconfined compressive strength (UCS) tests were carried out at 7 and 28 days of curing, and the results were correlated with microstructural analyses using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The findings revealed that the mixture containing 0.1 % NRL and a G/N ratio of 1:1 exhibited the highest UCS values of 4.0 MPa and 5.17 MPa at 7 and 28 days respectively, surpassing the minimum strength requirement for pavement subbase materials. The microstructural analyses confirmed the constitution of a dense and homogeneous geopolymer matrix, with NRL films acting as bridging structures that enhanced the bonding between RCA particles and the matrix. Higher ratios of G/N led to a silica-rich gel that hindered further geopolymerization and strength gain. Meanwhile, a higher ratio of NRL resulted in the formation of thicker NRL films that interfered with the geopolymerization process, resulting in a subsequent strength reduction. The study demonstrates the potential of NRL-modified BA-based geopolymer stabilized RCA as an environmentally friendly and high-performance alternative to conventional cement-stabilized pavement base materials.
{"title":"Performance of natural rubber latex modified bottom ash-based geopolymer stabilized recycled concrete aggregate as a pavement base material","authors":"Chokchai Traiyasut , Menglim Hoy , Suksun Horpibulsuk , Apichat Suddeepong , Apinun Buritatum , Teerasak Yaowarat , Artit Udomchai , Arul Arulrajah , Avirut Chinkulkijniwat , Punvalai Choenklang","doi":"10.1016/j.clet.2025.101080","DOIUrl":"10.1016/j.clet.2025.101080","url":null,"abstract":"<div><div>The present research assessed the performance of natural rubber latex (NRL) modified bottom ash (BA)-based geopolymer stabilized recycled concrete aggregate (RCA) as a sustainable pavement base material. Effects of NRL content (0.1, 0.2 %, and 0.3 % by weight of aggregate) and alkaline activator ratios (NaOH:Na<sub>2</sub>SiO<sub>3</sub>, G/N = 1:1, 1:1., and 1:2) in strength development and microstructure of the stabilized mixtures were evaluated. Unconfined compressive strength (UCS) tests were carried out at 7 and 28 days of curing, and the results were correlated with microstructural analyses using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The findings revealed that the mixture containing 0.1 % NRL and a G/N ratio of 1:1 exhibited the highest UCS values of 4.0 MPa and 5.17 MPa at 7 and 28 days respectively, surpassing the minimum strength requirement for pavement subbase materials. The microstructural analyses confirmed the constitution of a dense and homogeneous geopolymer matrix, with NRL films acting as bridging structures that enhanced the bonding between RCA particles and the matrix. Higher ratios of G/N led to a silica-rich gel that hindered further geopolymerization and strength gain. Meanwhile, a higher ratio of NRL resulted in the formation of thicker NRL films that interfered with the geopolymerization process, resulting in a subsequent strength reduction. The study demonstrates the potential of NRL-modified BA-based geopolymer stabilized RCA as an environmentally friendly and high-performance alternative to conventional cement-stabilized pavement base materials.</div></div>","PeriodicalId":34618,"journal":{"name":"Cleaner Engineering and Technology","volume":"29 ","pages":"Article 101080"},"PeriodicalIF":6.5,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098082","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 : 2025-09-13DOI: 10.1016/j.clet.2025.101074
Harn Wei Kua, Anqi Shi , Vignesh Kajandran, Charlene, Tiam Weng Mark Lam, Abhimanyu Goel, De Hui Alwin Wong, Peak Kee Lim, Layla Harris Kasee, Xi Wen Ong, Ghasan Fahem Huseien, Alexander Lin
This study investigates the effects of partial substitution of Ordinary Portland Cement with different proportions of non-calcined marine clay and different grades (by particle size) of Ground Limestone to formulate 3D-printable concrete. Non-calcined clay was used because of its lower energy requirement than calcined clay. The rheology of the mixes was evaluated by extrudability, tack, Large Amplitude Oscillatory shear, and Logarithmic Stress Ramp tests. Their mechanical performance was evaluated with respect to compressive, splitting, shear, and three-point bending (flexural) strengths. Results show that adding only about 1 % of oven-dried (low temperature) marine clay and 19 % of limestone improve cohesion and build-up of static yield strength while ensuring extrudability. This study hopes to pave the way for more studies on using non-calcined marine clay as a more sustainable option for construction 3D printing.
{"title":"Toward sustainable construction 3D printing: limestone and non-calcined recycled marine clay as partial cement replacement","authors":"Harn Wei Kua, Anqi Shi , Vignesh Kajandran, Charlene, Tiam Weng Mark Lam, Abhimanyu Goel, De Hui Alwin Wong, Peak Kee Lim, Layla Harris Kasee, Xi Wen Ong, Ghasan Fahem Huseien, Alexander Lin","doi":"10.1016/j.clet.2025.101074","DOIUrl":"10.1016/j.clet.2025.101074","url":null,"abstract":"<div><div>This study investigates the effects of partial substitution of Ordinary Portland Cement with different proportions of non-calcined marine clay and different grades (by particle size) of Ground Limestone to formulate 3D-printable concrete. Non-calcined clay was used because of its lower energy requirement than calcined clay. The rheology of the mixes was evaluated by extrudability, tack, Large Amplitude Oscillatory shear, and Logarithmic Stress Ramp tests. Their mechanical performance was evaluated with respect to compressive, splitting, shear, and three-point bending (flexural) strengths. Results show that adding only about 1 % of oven-dried (low temperature) marine clay and 19 % of limestone improve cohesion and build-up of static yield strength while ensuring extrudability. This study hopes to pave the way for more studies on using non-calcined marine clay as a more sustainable option for construction 3D printing.</div></div>","PeriodicalId":34618,"journal":{"name":"Cleaner Engineering and Technology","volume":"29 ","pages":"Article 101074"},"PeriodicalIF":6.5,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269617","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}
The increasing discharge of nutrient-rich industrial effluents poses a significant environmental challenge, necessitating efficient and sustainable wastewater treatment strategies. This study developed a living hydrogel-based biofilter incorporating co-immobilized Chlorella sp. and Bacillus subtilis TISTR 1415 to enhance nutrient recovery from secondary industrial effluent from vegetable oil factories. Hydrogels were formulated using guar gum and carrageenan, crosslinked with potassium chloride (KCl), and evaluated for their stability and microbial immobilization efficiency. Among the tested formulations, the hydrogel with 0.3 M KCl exhibited optimal properties, including moderate swelling capacity (∼1,005 % or ∼10 gwater/gdry hydrogel), reduced solubility (∼40 %), and enhanced mechanical stability and crosslinking density, leading to improved porosity and microbial retention. These physicochemical properties facilitated efficient nutrient diffusion and sustained cell viability within the hydrogel matrix. The synthetic co-culture biofilter with a 3:1 ratio of Chlorella sp. to B. subtilis significantly enhanced nutrient removal efficiencies compared to monocultures, achieving 98.68 % ammonium (NH4+), 53.45 % phosphate (PO43−), and 68.60 % COD removal over 7-day trials. The synergistic interaction between microalgae and bacteria facilitated improved nutrient uptake, organic matter degradation, and enhanced effluent treatment performance. Furthermore, pH and dissolved oxygen levels were significantly influenced by microbial activity, with microalgae contributing to oxygen production and pH elevation, while bacteria aided organic matter breakdown. The living hydrogel-based biofilter presents a promising alternative to conventional wastewater treatment methods by harnessing the synergistic interactions between biological processes and hydrogel immobilization technology. This approach enhances effluent quality and contributes to innovative solutions for environmental protection and nutrient recovery.
富含营养物质的工业废水排放的增加对环境构成了重大挑战，因此需要有效和可持续的废水处理战略。以小球藻和枯草芽孢杆菌TISTR 1415为载体，开发了一种活性水凝胶生物过滤器，以提高植物油厂二级工业废水的养分回收率。以瓜尔胶和卡拉胶为原料，与氯化钾交联制备水凝胶，并对其稳定性和微生物固定化效率进行了评价。在测试的配方中，含有0.3 M KCl的水凝胶表现出最佳的性能，包括适度的膨胀能力（~ 1005%或~ 10 gwater/gdry水凝胶），降低溶解度（~ 40%），增强机械稳定性和交联密度，从而改善孔隙度和微生物保留率。这些物理化学性质促进了营养物质在水凝胶基质内的有效扩散和维持细胞活力。与单一培养相比，小球藻与枯草芽孢杆菌比例为3:1的合成共培养生物过滤器显著提高了营养物去除效率，在7天的试验中，铵（NH4+）去除率达到98.68%，磷酸盐（PO43−）去除率达到53.45%，COD去除率达到68.60%。微藻和细菌之间的协同作用促进了养分吸收、有机物降解和污水处理性能的提高。此外，pH和溶解氧水平受微生物活动的显著影响，微藻有助于产氧和pH升高，而细菌有助于有机物分解。水凝胶生物过滤器利用生物过程和水凝胶固定化技术之间的协同作用，为传统的废水处理方法提供了一种有前途的替代方案。这种方法提高了污水的质量，并为环境保护和养分回收提供了创新的解决方案。
{"title":"Bio-hydrogel formulation for co-immobilization of microalgae and bacteria in living biofilters for nutrient recovery from secondary industrial effluents","authors":"Chalampol Janpum , Jagroop Pandhal , Nuttapon Pombubpa , Tanakit Komkhum , Chonnikarn Sirichan , Piyakorn Srichuen , Pichaya In-na","doi":"10.1016/j.clet.2025.101075","DOIUrl":"10.1016/j.clet.2025.101075","url":null,"abstract":"<div><div>The increasing discharge of nutrient-rich industrial effluents poses a significant environmental challenge, necessitating efficient and sustainable wastewater treatment strategies. This study developed a living hydrogel-based biofilter incorporating co-immobilized <em>Chlorella</em> sp. and <em>Bacillus subtilis</em> TISTR 1415 to enhance nutrient recovery from secondary industrial effluent from vegetable oil factories. Hydrogels were formulated using guar gum and carrageenan, crosslinked with potassium chloride (KCl), and evaluated for their stability and microbial immobilization efficiency. Among the tested formulations, the hydrogel with 0.3 M KCl exhibited optimal properties, including moderate swelling capacity (∼1,005 % or ∼10 g<sub>water</sub>/g<sub>dry hydrogel</sub>), reduced solubility (∼40 %), and enhanced mechanical stability and crosslinking density, leading to improved porosity and microbial retention. These physicochemical properties facilitated efficient nutrient diffusion and sustained cell viability within the hydrogel matrix. The synthetic co-culture biofilter with a 3:1 ratio of <em>Chlorella</em> sp. to <em>B. subtilis</em> significantly enhanced nutrient removal efficiencies compared to monocultures, achieving 98.68 % ammonium (NH<sub>4</sub><sup>+</sup>), 53.45 % phosphate (PO<sub>4</sub><sup>3−</sup>), and 68.60 % COD removal over 7-day trials. The synergistic interaction between microalgae and bacteria facilitated improved nutrient uptake, organic matter degradation, and enhanced effluent treatment performance. Furthermore, pH and dissolved oxygen levels were significantly influenced by microbial activity, with microalgae contributing to oxygen production and pH elevation, while bacteria aided organic matter breakdown. The living hydrogel-based biofilter presents a promising alternative to conventional wastewater treatment methods by harnessing the synergistic interactions between biological processes and hydrogel immobilization technology. This approach enhances effluent quality and contributes to innovative solutions for environmental protection and nutrient recovery.</div></div>","PeriodicalId":34618,"journal":{"name":"Cleaner Engineering and Technology","volume":"29 ","pages":"Article 101075"},"PeriodicalIF":6.5,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060739","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 : 2025-09-08DOI: 10.1016/j.clet.2025.101076
Daniel O.F. Silva , Valdir M. Pereira , Antônio C.V. Coelho , Sérgio C. Angulo
Concrete slurry waste (CSW) is a by-product generated from returned concrete and the mixer truck washing process, accounting for approximately 3–5% of total concrete production. Although various strategies for recycling CSW have been developed, large-scale recovery of its anhydrous cement fraction, such implemented in the present study, has not been previously reported. Moreover, prior studies have focused almost exclusively on the use of low-reactivity CSW as a supplementary cementitious material (SCM). In this study, a filtering and rapid drying procedure was applied to CSW upon its return to the ready-mixed concrete plant (RMCP). The influence of the recovery time and type of concrete waste on the preservation of the anhydrous cement fraction was evaluated. The recovered material was subsequently used to partially replace Portland cement in cementitious paste formulations. The samples were characterized using analytical methods, such X-ray fluorescence, HCl leaching assay, thermogravimetric analysis, isothermal calorimetry, and quantitative X-ray diffraction (QXRD). The results demonstrated that the anhydrous cement content in CSW was significant, approximately 30% by mass, due to the efficiency of the filtering and rapid drying process. Furthermore, the time exposure to water had no notable effect on the preserved anhydrous cement fraction. Three CSW samples were selected and incorporated into cement pastes, replacing 35 %–75% (by mass) of Portland cement. The resulting pastes exhibited mechanical strength values comparable to, or statistically equivalent to, those of the reference paste made with 100 % Portland cement. The recovery methodology has potential for the development of zero-waste ready-mix concrete plants, and the low emission concrete formulation proposed in this study enabled a reduction of up to 55% in specific CO2 emissions. This approach could reduce Portland cement consumption by approximately 15% (by mass) in ready-mix operations, contributing significantly to sustainability in the concrete industry.
{"title":"High recovery of anhydrous cement in dried concrete slurry waste for use as supplementary cementitious material in low-CO2 concretes","authors":"Daniel O.F. Silva , Valdir M. Pereira , Antônio C.V. Coelho , Sérgio C. Angulo","doi":"10.1016/j.clet.2025.101076","DOIUrl":"10.1016/j.clet.2025.101076","url":null,"abstract":"<div><div>Concrete slurry waste (CSW) is a by-product generated from returned concrete and the mixer truck washing process, accounting for approximately 3–5% of total concrete production. Although various strategies for recycling CSW have been developed, large-scale recovery of its anhydrous cement fraction, such implemented in the present study, has not been previously reported. Moreover, prior studies have focused almost exclusively on the use of low-reactivity CSW as a supplementary cementitious material (SCM). In this study, a filtering and rapid drying procedure was applied to CSW upon its return to the ready-mixed concrete plant (RMCP). The influence of the recovery time and type of concrete waste on the preservation of the anhydrous cement fraction was evaluated. The recovered material was subsequently used to partially replace Portland cement in cementitious paste formulations. The samples were characterized using analytical methods, such X-ray fluorescence, HCl leaching assay, thermogravimetric analysis, isothermal calorimetry, and quantitative X-ray diffraction (QXRD). The results demonstrated that the anhydrous cement content in CSW was significant, approximately 30% by mass, due to the efficiency of the filtering and rapid drying process. Furthermore, the time exposure to water had no notable effect on the preserved anhydrous cement fraction. Three CSW samples were selected and incorporated into cement pastes, replacing 35 %–75% (by mass) of Portland cement. The resulting pastes exhibited mechanical strength values comparable to, or statistically equivalent to, those of the reference paste made with 100 % Portland cement. The recovery methodology has potential for the development of zero-waste ready-mix concrete plants, and the low emission concrete formulation proposed in this study enabled a reduction of up to 55% in specific CO<sub>2</sub> emissions. This approach could reduce Portland cement consumption by approximately 15% (by mass) in ready-mix operations, contributing significantly to sustainability in the concrete industry.</div></div>","PeriodicalId":34618,"journal":{"name":"Cleaner Engineering and Technology","volume":"29 ","pages":"Article 101076"},"PeriodicalIF":6.5,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159100","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 : 2025-09-01DOI: 10.1016/j.clet.2025.101063
Nishtha Talwar , Oscar Huerta , Daniela Millán , Paulina Pavez , Mauricio Isaacs , Nicholas M. Holden
Green chemistry promotes the design and application of chemical products and processes that reduce or preferably eliminate the use and generation of hazardous substances. The objective of this research was to evaluate the environmental performance of two methods of producing nanocellulose at the laboratory scale: (i) a conventional sulphuric acid hydrolysis that has been upscaled for industrial use (TRL 8–9); and (ii) the novel approach using the ternary eutectic mixture ChCl: pTSA: PA molar ratio (1:1:1.35) that is currently at TRL 2. The purpose of developing the new approach was to find a better alternative to the conventional process from an environmental perspective. To validate this, life cycle assessment was used to compare conventional vs novel methods with the functional unit of 1 g nanocellulose produced. The system boundary was from cradle to laboratory gate. The results were interpreted to select the best method for laboratory use and to identify design issues to address during upscaling of the novel method. For both methods, conventional and novel, the impact categories selected were climate change (kgCO2 eq), Acidification (kg SO2 eq), Ecotox Air (CTUe) and Eutrophication (kg N eq). To produce 1 g of nanocellulose with sulphuric acid caused a climate impact of between 68 kg CO2 eq (90 % yield) to 105 kg CO2 eq (57 % yield). Produced using DES the climate impact ranged from 85 kg CO2 eq.(90 % yield) to 132 kg CO2 (57 % yield). The results indicated that the novel method created greater impacts over the whole life cycle. Unless significant changes are made during upscaling, the novel method will not make a positive contribution to sustainable, circular bioeconomy. The method does have potential to be improved to reduce impact, including using decarbonised energy, a renewable, bio-based feedstock for the cellulose and choline chloride to improve the overall efficiency of using deep eutectic solvent (DES) at pilot scale. The low TRL life cycle assessment offered insights not possible if only the laboratory stage of the analysis had been considered.
{"title":"Evaluating the environmental impacts of nanocellulose production using conventional and novel approach at laboratory scale","authors":"Nishtha Talwar , Oscar Huerta , Daniela Millán , Paulina Pavez , Mauricio Isaacs , Nicholas M. Holden","doi":"10.1016/j.clet.2025.101063","DOIUrl":"10.1016/j.clet.2025.101063","url":null,"abstract":"<div><div>Green chemistry promotes the design and application of chemical products and processes that reduce or preferably eliminate the use and generation of hazardous substances. The objective of this research was to evaluate the environmental performance of two methods of producing nanocellulose at the laboratory scale: (i) a conventional sulphuric acid hydrolysis that has been upscaled for industrial use (TRL 8–9); and (ii) the novel approach using the ternary eutectic mixture ChCl: pTSA: PA molar ratio (1:1:1.35) that is currently at TRL 2. The purpose of developing the new approach was to find a better alternative to the conventional process from an environmental perspective. To validate this, life cycle assessment was used to compare conventional vs novel methods with the functional unit of 1 g nanocellulose produced. The system boundary was from cradle to laboratory gate. The results were interpreted to select the best method for laboratory use and to identify design issues to address during upscaling of the novel method. For both methods, conventional and novel, the impact categories selected were climate change (kgCO2 eq), Acidification (kg SO2 eq), Ecotox Air (CTUe) and Eutrophication (kg N eq). To produce 1 g of nanocellulose with sulphuric acid caused a climate impact of between 68 kg CO2 eq (90 % yield) to 105 kg CO2 eq (57 % yield). Produced using DES the climate impact ranged from 85 kg CO2 eq.(90 % yield) to 132 kg CO2 (57 % yield). The results indicated that the novel method created greater impacts over the whole life cycle. Unless significant changes are made during upscaling, the novel method will not make a positive contribution to sustainable, circular bioeconomy. The method does have potential to be improved to reduce impact, including using decarbonised energy, a renewable, bio-based feedstock for the cellulose and choline chloride to improve the overall efficiency of using deep eutectic solvent (DES) at pilot scale. The low TRL life cycle assessment offered insights not possible if only the laboratory stage of the analysis had been considered.</div></div>","PeriodicalId":34618,"journal":{"name":"Cleaner Engineering and Technology","volume":"28 ","pages":"Article 101063"},"PeriodicalIF":6.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145019214","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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