Sustainability

2024

Jump to: 2023, 2022, 2021, 2020

17 pages, 1301 KiB

Open AccessArticle

The Testing Results of ACORGA, LIX Extractants and CR60 Crud Mitigation Reagent Influence during SX-EW Copper Extraction

by Tatyana Chepushtanova, Meiyrbek Yessirkegenov, Yelena Bochevskaya, Ainash Sharipova, Omirserik Baigenzhenov, Yerik Merkibayev and Aliya Altmyshbayeva

Sustainability 2024, 16(17), 7815; https://doi.org/10.3390/su16177815 - 8 Sep 2024

Viewed by 986

Abstract

Research analysis reveals factors influencing third-phase crud formation and composition during metal extraction, including solution composition, solid suspensions, organic compounds, colloidal compounds (e.g., silicic acid), and extractant purity. Compositional analysis of copper-containing sulfuric acid solutions (1.25 g/dm³ copper) identifies principal sulfate-forming components. [...] Read more.

Research analysis reveals factors influencing third-phase crud formation and composition during metal extraction, including solution composition, solid suspensions, organic compounds, colloidal compounds (e.g., silicic acid), and extractant purity. Compositional analysis of copper-containing sulfuric acid solutions (1.25 g/dm³ copper) identifies principal sulfate-forming components. Copper extraction was studied using extractants LIX 984N, ACORGA M5774, and M5640 at different ratios of the organic phase to the aqueous O:A (from 1:2 to 1:10). Suppressive impact of 10 vol.% CR60 additive on third-phase crud formation during copper extraction with LIX 984N, ACORGA M5774, and M5640 is analyzed, with ACORGA M5774 being the most effective. Physicochemical analysis characterizes CR60’s active substance as poly(sodium 4-styrenesulfonate) with steel-suppression properties, and its structural formula is determined. Optimal copper extraction conditions establish ACORGA M5640’s 24% efficiency, followed by ACORGA M5774 at 15%. CR60 reduces crud formation, with 5 cm³ of ACORGA CR60 added to sulfuric acid solution reducing interfacial crud formation by 2–3 times. Optimal extraction parameters include 1:2 O:A ratio, 20 ± 5 °C temperature, 5 cm³ CR60 additive, 5 min process duration, and 1-day settling time. ACORGA M5774 (10 vol.% in kerosene) is recommended as an extractant, with 2–3 stages of countercurrent extraction. Full article

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16 pages, 3816 KiB

Open AccessArticle

Combined Potential of Quarry Waste Fines and Eggshells for the Hydrothermal Synthesis of Tobermorite at Varying Cement Content

by Shem Saldia, Hernando Bacosa, Maria Cristina Vegafria, Joshua Zoleta, Naoki Hiroyoshi, Ernesto Empig, Christian Calleno, Wilyneth Cantong, Ephraim Ibarra, Maricar Aguilos and Ruben Amparado, Jr.

Sustainability 2024, 16(6), 2401; https://doi.org/10.3390/su16062401 - 14 Mar 2024

Viewed by 2010

Abstract

Quarry waste fines and eggshells are unavoidable wastes which relentlessly contribute to environmental loads and pollution. Although many studies have suggested various methods for recycling, these wastes remain underutilized due to some technical constraints. In addition, no study has yet explored the possibility [...] Read more.

Quarry waste fines and eggshells are unavoidable wastes which relentlessly contribute to environmental loads and pollution. Although many studies have suggested various methods for recycling, these wastes remain underutilized due to some technical constraints. In addition, no study has yet explored the possibility of combining quarry waste fines (QWF) and eggshell powder (ESP) for tobermorite synthesis. Tobermorite is the main component which primarily provides strength to autoclaved aerated concrete products. With this in mind, this study seeks to evaluate the potential of QWF-ESP mix at 10%, 15%, and 20% amounts of cement, respectively. The XRF, XRD, and TGA–DTA techniques were used to characterize the waste materials, while physical and mechanical property tests and XRD analysis were performed on the autoclaved samples. It was found that QWF contains 53.77% SiO₂ and ESP contains 97.8% CaO which are key components for tobermorite synthesis. This study also revealed that the mixture with only 10% cement has the highest compressive strength among the QWF-ESP samples. Furthermore, the formation of tobermorite in the samples was confirmed through XRD analysis. Hence, the hydrothermal curing of QWF-ESP can be further developed to produce functional tobermorite-bearing materials. Full article

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2023

Jump to: 2024, 2022, 2021, 2020

13 pages, 17644 KiB

Open AccessArticle

Comparison of the Properties of Coal Gasification Fly Ash and Pulverized Coal Fly Ash as Supplementary Cementitious Materials

by Feng Luo and Yujie Jin

Sustainability 2023, 15(20), 14960; https://doi.org/10.3390/su152014960 - 17 Oct 2023

Cited by 3 | Viewed by 1266

Abstract

Using industrial waste as part of the raw material to produce cement-based materials is considered to be a sustainable cement and concrete materials production method. Coal gasification fly ash (hereafter CGFA) is a solid waste produced during the coal gasification process. Similar to [...] Read more.

Using industrial waste as part of the raw material to produce cement-based materials is considered to be a sustainable cement and concrete materials production method. Coal gasification fly ash (hereafter CGFA) is a solid waste produced during the coal gasification process. Similar to pulverized coal fly ash (hereafter PCFA), it is also a kind of fly ash discharged from combustion coal furnaces. With the development of coal gasification technology, more and more CGFA needs to be treated. Based on the successful experience of PCFA as a supplementary cementitious material in cement-based materials, CGFA is used as a supplementary cementitious material in this paper. A comparison of the performance of two coal-based fly ashes as a supplementary cementitious material (hereafter SCM) was conducted. The effects of two fly ashes on the fluidity and strength of cement mortar were discussed, and the mechanism was analyzed from the mineral composition and morphology of hydration products. At the same time, the properties of CGFA and ultrafine CGFA (UFCGFA) as an SCM were compared. The results show that CGFA has more negative effects on the fluidity of cement mortar than PCFA. But it has a greater contribution to the strength of cement mortar than PCFA. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results show that the active components of CGFA participate in the hydration reaction faster, showing a stronger pozzolanic reactivity than PCFA. Ultrafine treatment of CGFA not only improves the pozzolanic activity but also reduces the negative effect on the fluidity of cement mortar. The contribution of UFCGFA to the fluidity and strength of cement mortar can be greatly improved. Full article

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26 pages, 6540 KiB

Open AccessArticle

Assessment and Characterization of Duck Feathers as Potential Source of Biopolymers from an Upcycling Perspective

by Sandra Alvarez, Nidal Del Valle Raydan, Isabelle Svahn, Etienne Gontier, Klaus Rischka, Bertrand Charrier and Eduardo Robles

Sustainability 2023, 15(19), 14201; https://doi.org/10.3390/su151914201 - 26 Sep 2023

Cited by 4 | Viewed by 2914

Abstract

A comprehensive characterization of the physical and chemical properties of whole duck feathers from French mulard species, including their various categories and fractions (barbs, rachis, and calamus), was conducted to explore potential ways for utilizing this waste product. This analysis aimed to identify [...] Read more.

A comprehensive characterization of the physical and chemical properties of whole duck feathers from French mulard species, including their various categories and fractions (barbs, rachis, and calamus), was conducted to explore potential ways for utilizing this waste product. This analysis aimed to identify opportunities for valorizing these feathers and unlocking their untapped potential. Hence, the duck feathers were thoroughly characterized by a proximate analysis to determine their composition and theoretical heating value. Additionally, feathers underwent other analyses as Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) analysis, solvent behavior and chemical durability assessment, hydrophobicity testing, Fourier Transform Infrared (FT-IR) spectroscopy, Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). The analyses revealed duck feather composition, molecular weight, stability in different environments, hydrophobicity, functional groups present, thermal behavior, crystallinity, and structural arrangement. Upon analysis, it was determined that duck feathers contain pure fiber keratin and possess characteristics that make them suitable for the production of high-value keratin-based products, including cosmetics, activated carbon for purification, materials for waterproofing, lightweight construction, and textile innovations, underscoring their potential to support sustainable and eco-friendly initiatives across various sectors. Full article

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19 pages, 2162 KiB

Open AccessArticle

Utilization of Food Waste for the Development of Composite Bread

by Shuchi Upadhyay, Rajeev Tiwari, Sanjay Kumar, Shradhha Manish Gupta, Vinod Kumar, Indra Rautela, Deepika Kohli, Bhupendra S. Rawat and Ravinder Kaushik

Sustainability 2023, 15(17), 13079; https://doi.org/10.3390/su151713079 - 30 Aug 2023

Cited by 4 | Viewed by 2184

Abstract

The development of highly nutritious bakery products with optimum utilization of food waste is a major challenge for the food industry. The optimum utilization of food waste for the sustainable development goal of the country is important for the growth of the nation. [...] Read more.

The development of highly nutritious bakery products with optimum utilization of food waste is a major challenge for the food industry. The optimum utilization of food waste for the sustainable development goal of the country is important for the growth of the nation. The aim of the present work is to prepare value-added composite flour-mixed bread from waste fruit and vegetables. The composite flour was prepared in four formulations of peel and pomace with wheat flour (PPWF), as PPWF1, PPWF2, PPWF3, and PPWF4. Composite flour was blended with a mix of vegetable and fruit pomace powders and whole wheat flour. Indian gooseberry pomace powder, apple pomace powder, bottle gourd peel powder, and potato peel powder were used with whole wheat flour to make pomace and whole wheat flour compositions such as PPWF1, PPWF2, PPWF3, and PPWF4. Out of these four flours, PPWF3 contained a good amount of fiber 8.16%, crude protein 3.18%, total phenolic content 14.48%, moisture 9.5%, vitamin C 13.64 mg/100 g, and total phenolic compound 14.48 (mg/GAE/g), which are maximum and acceptable range values as compared to the other three composite flours and the control group flour. PPWF3 is used as a partial replacement ratio for wheat flour due to its high phenolic content, vitamin C content, and richness in fibers. This composite flour is used to make bread dough, and two samples, G1 and G2, are made, out of which G2 offers better nutritional, functional, and sensory evaluations in comparison with refined wheat bread, which is taken as a control group. Thus, such utilization of food waste in bread making can generate value from waste and improve the nutritional attributes of bread, which may improve an individual’s health. Full article

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27 pages, 2800 KiB

Open AccessArticle

A Decision Framework for Designing Sustainable Wastewater-Based Resource Recovery Schemes

by Nancy Diaz-Elsayed, Jiayi Hua, Nader Rezaei and Qiong Zhang

Sustainability 2023, 15(4), 3839; https://doi.org/10.3390/su15043839 - 20 Feb 2023

Viewed by 1762

Abstract

The availability of sufficient water supply is a challenge many municipalities have faced in recent decades and a challenge that is expected to intensify with time. While several choices remain for selecting alternatives to freshwater sources, water reclamation offers an opportunity for sustainable [...] Read more.

The availability of sufficient water supply is a challenge many municipalities have faced in recent decades and a challenge that is expected to intensify with time. While several choices remain for selecting alternatives to freshwater sources, water reclamation offers an opportunity for sustainable resource recovery. Nonetheless, tradeoffs exist in the selection of the most sustainable technology for recovering resources from wastewater when long-term impacts are taken into consideration. This article investigates the factors influencing the environmental and economic impacts of resource recovery technologies through the analysis of life cycle environmental and economic impact case studies. Key characteristics were extracted from life cycle assessment and life cycle cost case studies to evaluate the factors influencing the sustainability of the resource recovery systems. The specific design parameters include the type of resources to be recovered, technology utilized, scale of implementation, location, and end users. The design of sustainable resource recovery systems was found to be largely driven by scale, location (e.g., as it pertains to the energy mix and water quality restrictions), and the scope of the system considered. From this analysis, a decision framework for resource recovery-oriented wastewater management was developed and then applied to an existing case study to demonstrate its usability. Full article

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2022

Jump to: 2024, 2023, 2021, 2020

18 pages, 3613 KiB

Open AccessArticle

Recovery of Sugar and Nutrients from Algae and Colocasia esculenta (Taro) Leaves Using Chemical Hydrolysis

by Swati Dahiya, Raja Chowdhury, Pradeep Kumar, Sanjoy Ghosh and Asha Srinivasan

Sustainability 2022, 14(24), 16383; https://doi.org/10.3390/su142416383 - 7 Dec 2022

Cited by 1 | Viewed by 2077

Abstract

Algal biomass and Colocasia esculenta (Taro) leaves are available as waste biomass all over India. These biomasses can be used as renewable and sustainable resources for sugars and nutrients. Recovered nutrients and sugars can be used as cheap raw materials for biofuels and [...] Read more.

Algal biomass and Colocasia esculenta (Taro) leaves are available as waste biomass all over India. These biomasses can be used as renewable and sustainable resources for sugars and nutrients. Recovered nutrients and sugars can be used as cheap raw materials for biofuels and biomaterials production. The hydrolysis of dried algal biomass and Colocasia esculenta (Taro) leaves were investigated using 1%, 2%, and 5% solutions of ferric-chloride, nitric acid, and acetic acid for the reaction times of 30 and 60 min at 121 °C and 103.4 kPa (15 psi). 1% and 2% H₂SO₄ treatments were used as the reference. The solid: liquid ratio was kept at 1:10 for all the experiments. For algal biomass, a 5% acetic acid treatment for 60 min was found to be optimum with a total carbohydrate release of 44.2 mg/g biomass (solubilized monomers-0.82 mg/g of biomass) and N and P solubilization of 1.8 mg total nitrogen/g biomass and 7 mg total phosphorus/g biomass. Moreover, for Colocasia esculenta (Taro) leaves, the maximum carbohydrate yield of 95 mg/g biomass (solubilized monomers-43.6 mg/g of biomass) and nutrient solubilization of 5.02 mg total nitrogen/g biomass was obtained with 5% ferric chloride treatment for 60 min. The results obtained showed that various hydrolyzing agents used in this study acted differently on different types of biomasses. Acetic acid worked best in hydrolyzing the algal biomass, and for the hydrolysis of Taro leaves, ferric chloride and nitric acid were effective. Statistical analysis showed that the chemical concentration was one of the prime factors for releasing P from algal biomass. For carbohydrate release from Taro leaves, either time or concentration, or both, were the prime factors that affected the carbohydrate release. Full article

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18 pages, 1287 KiB

Open AccessArticle

The Evolution of the Construction Waste Recycling System and the Willingness to Use Recycled Products in China

by Yixin Wang, Huiqin Li, Lanlan Xue and Wenjuan Gou

Sustainability 2022, 14(19), 12541; https://doi.org/10.3390/su141912541 - 1 Oct 2022

Cited by 10 | Viewed by 1925

Abstract

This paper establishes a recycling system for construction waste and simulates the operation of its four links using the theory and method of system dynamics. In addition, based on the technology acceptance model and the theory of planned behavior, a research model on [...] Read more.

This paper establishes a recycling system for construction waste and simulates the operation of its four links using the theory and method of system dynamics. In addition, based on the technology acceptance model and the theory of planned behavior, a research model on the willingness of purchasers to use recycled products of construction waste is established, and the factors influencing willingness to use recycled products are analyzed using structural equations. Results show that the operation trend of the building waste recycling subsystem and information feedback subsystem is relatively poor. Purchasers’ perceived ease of use of recycled products correlates positively with their perceived usefulness, and attitude toward use correlates positively with behavioral intention, which promotes willingness to use. The attitudes toward use, behavioral intention, and intention to use are all negatively correlated with purchasers’ perceived risk of recycled products, with the negative correlation being stronger for behavioral intention and attitude toward use. The results of this study provide a theoretical foundation for promoting the process of recycling construction waste. Full article

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11 pages, 738 KiB

Open AccessArticle

Features of Metallic Ion Distribution in Non-Traditional Water Agricultural Applications in Sandy Loam in an Arid Area

by Liang Pei

Sustainability 2022, 14(17), 11080; https://doi.org/10.3390/su141711080 - 5 Sep 2022

Cited by 1 | Viewed by 1402

Abstract

Sandy loam is the main soil in the arid area of North China, which leads to serious water shortage. Therefore, the utilization of non-traditional water is necessary. However, there are many metal mining areas in the northern arid area. The mining process of [...] Read more.

Sandy loam is the main soil in the arid area of North China, which leads to serious water shortage. Therefore, the utilization of non-traditional water is necessary. However, there are many metal mining areas in the northern arid area. The mining process of these metal mines causes the pollution of surrounding water sources. It is important to study the distribution of pollutants in the process of unconventional water utilization around metal mines. In view of the above problems, a field test area was established near a mining area in a northern province to carry out research on non-traditional agricultural water applications. The influence of non-traditional agricultural water on pollutant distribution in balsam pear and sandy loam irrigation areas around a loam metal mine was analyzed. By discussing the influence of non-traditional water output after secondary treatment on the content and distribution characteristics of heavy metals in balsam pear in the sandy loam irrigation area around the metal mine, the distribution rules of heavy metals in the soil crop system under different non-traditional hydroponics conditions in the sandy loam irrigation area around the metal mine were analyzed. The results show that under different non-traditional agricultural water consumption conditions, there is no significant difference in terms of the content of heavy metals in the sandy loam irrigation area around the metal mine. The non-traditional water used for short-term agricultural application does not cause pollution of the loam environment and crops, nor does it cause heavy metal accumulation in the sandy loam irrigation area around the metal mine. The input and output have a minimal impact on the balance of heavy metals in the sandy loam irrigation area around the metal mine. The presented research results provide a scientific basis for agricultural utilization of non-traditional water around mining areas in arid areas. Full article

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2021

Jump to: 2024, 2023, 2022, 2020

13 pages, 1903 KiB

Open AccessArticle

Ultrasonic or Microwave Cascade Treatment of Medicinal Plant Waste

by Vasile Staicu, Cristina Luntraru, Ioan Calinescu, Ciprian Gabriel Chisega-Negrila, Mircea Vinatoru, Miruna Neagu, Adina Ionuta Gavrila and Ioana Popa

Sustainability 2021, 13(22), 12849; https://doi.org/10.3390/su132212849 - 20 Nov 2021

Cited by 2 | Viewed by 2064

Abstract

In this study, we present a strategy for valorizing lignocellulosic wastes (licorice root and willow bark) that result from industrial extraction of active principles using water as green solvent and aqueous NaOH solution. The wastes were submitted to severe ultrasound (US) and microwave [...] Read more.

In this study, we present a strategy for valorizing lignocellulosic wastes (licorice root and willow bark) that result from industrial extraction of active principles using water as green solvent and aqueous NaOH solution. The wastes were submitted to severe ultrasound (US) and microwave (MW) treatments. The aim of these treatments was to extract the remaining active principles (using water as a solvent) or to prepare them for cellulose enzymatic hydrolysis to hexoses (performed in an NaOH aqueous solution). The content of glycyrrhizic acid and salicin derivatives in licorice root and willow bark wastes, respectively, were determined. The best results for licorice root were achieved by applying the US treatment for 5 min at 25 °C (26.6 mg glycyrrhizic acid/gDM); while, for willow bark, the best results were achieved by applying the MW treatment for 30 min at 120 °C (19.48 mg salicin/gDM). A degradation study of the targeted compounds was also performed and showed good stability of glycyrrhizic acid and salicin derivatives under US and MW treatments. The soluble lignin concentration prior to enzymatic hydrolysis, as well as the saccharide concentration of the hydrolyzed solution, were determined. As compared with the MW treatment, the US treatment resulted in saccharides concentrations that were 5% and 160% higher for licorice root and willow bark, respectively. Full article

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16 pages, 3119 KiB

Open AccessArticle

Evaluation of Heavy Metal Tolerance Level of the Antarctic Bacterial Community in Biodegradation of Waste Canola Oil

by Khadijah Nabilah Mohd Zahri, Claudio Gomez-Fuentes, Suriana Sabri, Azham Zulkharnain, Khalilah Abdul Khalil, Sooa Lim and Siti Aqlima Ahmad

Sustainability 2021, 13(19), 10749; https://doi.org/10.3390/su131910749 - 28 Sep 2021

Cited by 6 | Viewed by 2908

Abstract

Heavy metal contamination is accidentally becoming prevalent in Antarctica, one of the world’s most pristine regions. Anthropogenic as well as natural causes can result in heavy metal contamination. Each heavy metal has a different toxic effect on various microorganisms and species, which can [...] Read more.

Heavy metal contamination is accidentally becoming prevalent in Antarctica, one of the world’s most pristine regions. Anthropogenic as well as natural causes can result in heavy metal contamination. Each heavy metal has a different toxic effect on various microorganisms and species, which can interfere with other pollutant bioremediation processes. This study focused on the effect of co-contaminant heavy metals on waste canola oil (WCO) biodegradation by the BS14 bacterial community collected from Antarctic soil. The toxicity of different heavy metals in 1 ppm of concentration to the WCO-degrading bacteria was evaluated and further analyzed using half maximal inhibition concentration (IC₅₀) and effective concentration (EC₅₀) tests. The results obtained indicated that Ag and Hg significantly impeded bacterial growth and degradation of WCO, while interestingly, Cr, As, and Pb had the opposite effect. Meanwhile, Cd, Al, Zn, Ni, Co, and Cu only slightly inhibited the bacterial community in WCO biodegradation. The IC₅₀ values of Ag and Hg for WCO degradation were found to be 0.47 and 0.54 ppm, respectively. Meanwhile, Cr, As, and Pb were well-tolerated and induced bacterial growth and WCO degradation, resulting in the EC₅₀ values of 3.00, 23.80, and 28.98 ppm, respectively. The ability of the BS14 community to tolerate heavy metals while biodegrading WCO in low-temperature conditions was successfully confirmed, which is a crucial aspect in biodegrading oil due to the co-contamination of oil and heavy metals that can occur simultaneously, and at the same time it can be applied in heavy metal-contaminated areas. Full article

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16 pages, 4888 KiB

Open AccessArticle

Mechanical Properties and Micro Mechanism of Nano-Clay-Modified Soil Cement Reinforced by Recycled Sand

by Biao Qian, Wenjie Yu, Beifeng Lv, Haibo Kang, Longxin Shu, Na Li and Wei Wang

Sustainability 2021, 13(14), 7758; https://doi.org/10.3390/su13147758 - 12 Jul 2021

Cited by 6 | Viewed by 2640

Abstract

To observe the effect of recycled sand and nano-clay on the improvement of the early strength of soil-cement (7d), 0%, 10%, 15% and 20% recycled sand were added. While maintaining a fixed moisture content of 30%, the ratios of each material are specified [...] Read more.

To observe the effect of recycled sand and nano-clay on the improvement of the early strength of soil-cement (7d), 0%, 10%, 15% and 20% recycled sand were added. While maintaining a fixed moisture content of 30%, the ratios of each material are specified in terms of soil mass percentage. The shear strength of CSR (recycled sand blended soil-cement) was investigated by direct shear test and four groups of specimens (CSR-1, CSR-2, CSR-3 and CSR-4) were obtained. In addition, 8% nano-clay was added to four CSR groups to obtain the four groups of CSRN-1, CSRN-2, CSRN-3 and CSRN-4 (soil-cement mixed with recycled sand and nano-clay), which were also subjected to direct shear tests. A detailed analysis of the modification mechanism of soil-cement by recycled sand and nano-clay was carried out in combination with scanning electron microscopy (SEM) and IPP (ImagePro-Plus) software. The test results showed that: (1) CSR-3 has the highest shear strength due to the “concrete-like” effect of the incorporation of recycled sand. With the addition of 8% nano-clay, the overall shear strength of the cement was improved, with CSRN-2 having the best shear strength, thanks to the filling effect of the nano-clay and its high volcanic ash content. (2) When recycled sand and nano-clay were added to soil-cement, the improvement in shear strength was manifested in a more reasonable macroscopic internal structure distribution of soil-cement. (3) SEM test results showed that the shear strength was negatively correlated with the void ratio of its microstructure. The smaller the void ratio, the greater the shear strength. This shows that the use of reclaimed sand can improve the sustainable development of the environment, and at the same time, the new material of nano-clay has potential application value. Full article

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4 pages, 446 KiB

Open AccessEditorial

A New Challenge for the Management and Disposal of Personal Protective Equipment Waste during the COVID-19 Pandemic

by Zheng Wang, Christophe Guy, Kelvin Tsun Wai Ng and Chunjiang An

Sustainability 2021, 13(13), 7034; https://doi.org/10.3390/su13137034 - 23 Jun 2021

Cited by 28 | Viewed by 4243

Abstract

To prevent the transmission of the Coronavirus (SARS-CoV-2) in the public, the demand and consumption of personal protective equipment (PPE) increased drastically. Such wide use of PPE has brough a new challenge to waste management and disposal. It is difficult to sort PPE [...] Read more.

To prevent the transmission of the Coronavirus (SARS-CoV-2) in the public, the demand and consumption of personal protective equipment (PPE) increased drastically. Such wide use of PPE has brough a new challenge to waste management and disposal. It is difficult to sort PPE waste before further treatment, and such waste will often end up being processed by some traditional disposal methods. During the pandemic, incineration and landfill facilities are currently under significant pressure. In addition, a certain amount of PPE waste is discarded into the environment rather than going to landfills and incinerators. It not only directly affects the ecosystem, but also indirectly threatens human health through various routes of exposure. PPE waste is also the source and carrier of pathogens and chemical contaminants, causing a secondary pollution. Therefore, it is necessary to establish appropriate strategies to deal with the PPE problems related to energy, environment and health, requiring the collaborative efforts of researchers, practitioners, policymakers, and governments. Full article

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23 pages, 7116 KiB

Open AccessArticle

Sustainable Glass Recycling Culture-Based on Semi-Automatic Glass Bottle Cutter Prototype

by Jovheiry García Guerrero, Juvenal Rodríguez Reséndiz, Hugo Rodríguez Reséndiz, José Manuel Álvarez-Alvarado and Omar Rodríguez Abreo

Sustainability 2021, 13(11), 6405; https://doi.org/10.3390/su13116405 - 4 Jun 2021

Cited by 7 | Viewed by 8406

Abstract

Humanity has developed recycling activities over time due to their benefits, the shortage of raw materials, or the footprint with regard to the environment. The absence of a recycling culture in Mexico has not allowed its development and growth despite the benefits. In [...] Read more.

Humanity has developed recycling activities over time due to their benefits, the shortage of raw materials, or the footprint with regard to the environment. The absence of a recycling culture in Mexico has not allowed its development and growth despite the benefits. In 2012, Mexico only recycled less than 10% of urban solid waste. Most recycling activities are focused on plastic, paper, and cardboard products due to their prices in local markets. This article presents a semi-automated prototype focused on recycling glass bottles using the thermal shock phenomenon. It aims to develop a sustainable glass recycling culture by creating a new branch for the integral glass recycling process and a proposal base on Integrated Sustainable Waste Management (ISWM) and the Quintuple Helix Model. It helps to reduce waste and resource recovery from recycling and upcycling glass bottles. The products obtained from upcycling fulfill new uses and acquire new value, while glass leftovers continue the integral recycling process for glass. Additionally, this paper demonstrates the relation between the ISWM and the Quintuple Helix Model and the opportunity to implement the twelfth Sustainable Development Goal (SDG). Full article

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13 pages, 3235 KiB

Open AccessArticle

On the Effect of Recycled Polyolefins on the Thermorheological Performance of Polymer-Modified Bitumen Used for Roofing-Applications

by Martin Wieser, Andreas Schaur, Seraphin Hubert Unterberger and Roman Lackner

Sustainability 2021, 13(6), 3284; https://doi.org/10.3390/su13063284 - 16 Mar 2021

Cited by 5 | Viewed by 2336

Abstract

In order to meet the technical specifications in roofing applications, the bitumen used for this purpose is standardly modified by polymers. This, in general, allows the re-use of recycled polymer during the production of polymer-modified bitumen (PmB), simultaneously reducing the amount of polymeric [...] Read more.

In order to meet the technical specifications in roofing applications, the bitumen used for this purpose is standardly modified by polymers. This, in general, allows the re-use of recycled polymer during the production of polymer-modified bitumen (PmB), simultaneously reducing the amount of polymeric waste. Recycling processes, however, may degrade or contaminate polymers, leading to reduced crystallinity and lower melting temperature. Six different recycled polyolefins (high crystallinity: iPP, HDPE; reduced crystallinity: APP, PP Copolymer; waxy polyolefins: Wax 105, Wax 115) were assessed on their suitability for roofing applications. Mixing characteristics, polymer distribution and thermo-mechanical properties of the PmB samples were determined, employing fluorescence microscopy, modulated temperature differential scanning calorimetry (MTDSC) and dynamic shear rheometry (DSR). Depending on mixing properties, two levels of polymer content (5 and 16 wt% or 16 and 30 wt%) were considered. High crystallinity polymers exhibited the biggest increase in |G*| and lowest phase angle. Reduced crystallinity polymers were more easily dispersed and showed improved |G*| and phase angle. Waxy polyolefins improved bitumen similarly to reduced crystallinity polymers and are easily dispersed. The results suggest, that a reduced crystallinity or lower melting temperature of the recycled polymers resulting from degradation or contamination may be beneficial, resulting in improved mixing behavior and a more homogeneous distribution of the polymer within the bitumen. Full article

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13 pages, 2067 KiB

Open AccessArticle

Parameter Optimization and Effect Analysis of Low-Pressure Abrasive Water Jet (LPAWJ) for Paint Removal of Remanufacturing Cleaning

by Sheng Xiong, Xiujie Jia, Shuangshuang Wu, Fangyi Li, Mingliang Ma and Xing Wang

Sustainability 2021, 13(5), 2900; https://doi.org/10.3390/su13052900 - 8 Mar 2021

Cited by 6 | Viewed by 2440

Abstract

As an environmentally friendly method, water jet (WJ) technology plays a significant role in the field of remanufacturing cleaning. The cleaning capacity of a WJ is severely restricted by the water pressure, while the impact force will be too large and may damage [...] Read more.

As an environmentally friendly method, water jet (WJ) technology plays a significant role in the field of remanufacturing cleaning. The cleaning capacity of a WJ is severely restricted by the water pressure, while the impact force will be too large and may damage the cleaned substrate as well as cause energy waste if the pressure is too high. However, by adding abrasives, the cleaning capacity of a low-pressure water jet (LPWJ) will be considerably improved. Although abrasive water jet (AWJ) technology has been used in mechanical machining for decades, very limited research work can be found in the literature for remanufacturing cleaning. In this paper, the role of abrasives in low-pressure abrasive water jet (LPAWJ) cleaning was described. Cleaning performance with different parameters (abrasive feed rate condition, water pressure and standoff distance) in paint removal was experimentally investigated by using the Taguchi design of experiment. The experimental results indicated that the water pressure was the most dominant factor and the optimal parameter combination was the second feed rate condition, 9 MPa water pressure and 300 mm standoff distance. The influence law between the cleaning performance and various factors was explored, which can provide remanufacturers with directions in selection of the optimal parameters in the LPAWJ cleaning process. By designing contrast experiments, the results showed that the cleaning capacity of an LPAWJ is better than that of a pure LPWJ and the residual effect in terms of changes in surface roughness, residual stress and morphology is a little larger. Full article

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12 pages, 5695 KiB

Open AccessArticle

Characterization of Carbonaceous Deposits on an End-of-Life Engines for Effective Cleaning for Remanufacturing

by Xing Wang, Jianfeng Li, Xiujie Jia, Mingliang Ma and Yuan Ren

Sustainability 2021, 13(2), 950; https://doi.org/10.3390/su13020950 - 19 Jan 2021

Cited by 2 | Viewed by 2064

Abstract

Remanufacturing is one of the most effective strategies to achieve sustainable manufacturing and restore the performance of end-of-life products. However, the lack of an effective cleaning method to clean carbonaceous deposits severely hampers the remanufacturing of end-of-life engines. To explore an appropriate cleaning [...] Read more.

Remanufacturing is one of the most effective strategies to achieve sustainable manufacturing and restore the performance of end-of-life products. However, the lack of an effective cleaning method to clean carbonaceous deposits severely hampers the remanufacturing of end-of-life engines. To explore an appropriate cleaning method, it is necessary to first study the characterization of the carbonaceous deposits. A broad range of analyses including X-ray fluorescence spectrometry, thermogravimetric analysis, ¹H-nuclear magnetic resonance study, X-ray diffraction analysis, and scanning electron microscopy were performed to conduct an in-depth characterization of the carbonaceous deposits. The results showed that a hybrid structure composed of organics and inorganics is the most distinguishing feature of the carbonaceous deposit in end-of-life engines. The inorganics form the skeleton on which organics get attached, thereby resulting in a strong adhesion of the deposit and increasing the difficulty of cleaning. Therefore, a method in which several cleaning forces can be simultaneously applied is more suitable for the present purpose. Molten salt cleaning was chosen to verify the feasibility of this proposal. This method was shown to have the potential to effectively clean the carbonaceous deposit. This finding could contribute towards promoting the effective remanufacturing of end-of-life engines. Full article

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2020

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9 pages, 220 KiB

Open AccessReview

Sustainable Utilization of Steel Slag from Traditional Industry and Agriculture to Catalysis

by Di Gao, Fu-Ping Wang, Yi-Tong Wang and Ya-Nan Zeng

Sustainability 2020, 12(21), 9295; https://doi.org/10.3390/su12219295 - 9 Nov 2020

Cited by 32 | Viewed by 4773

Abstract

Steel slag is a large amount of residual material produced in the process of steel manufacturing. With the requirements of sustainable development in China, the utilization of steel slag has become a hot issue. Through an in-depth study on steel slag, it is [...] Read more.

Steel slag is a large amount of residual material produced in the process of steel manufacturing. With the requirements of sustainable development in China, the utilization of steel slag has become a hot issue. Through an in-depth study on steel slag, it is apparent that it has been widely used in various fields in recent years. The resource utilization of steel slag is not only conducive to resource conservation, but also conducive to sustainable production and environmental protection. In this paper, the common ways of resource utilization of steel slag in construction, agriculture, industry, and catalysis are reviewed. Steel slag as a solid waste with great development potential and large output is expected to be widely developed into high value-added products such as catalytic material in the future. Full article

20 pages, 1451 KiB

Open AccessReview

The Benefits of Water Hyacinth (Eichhornia crassipes) for Southern Africa: A Review

by Obianuju P. Ilo, Mulala D. Simatele, S’phumelele L. Nkomo, Ntandoyenkosi M. Mkhize and Nagendra G. Prabhu

Sustainability 2020, 12(21), 9222; https://doi.org/10.3390/su12219222 - 6 Nov 2020

Cited by 54 | Viewed by 25098

Abstract

Globally, water hyacinth is a known invasive species that predominantly threatens the pillars of sustainability. The cost of controlling these invasive plants is high and many Southern African countries are barely equipped for this liability as the process has to be performed over [...] Read more.

Globally, water hyacinth is a known invasive species that predominantly threatens the pillars of sustainability. The cost of controlling these invasive plants is high and many Southern African countries are barely equipped for this liability as the process has to be performed over time. Despite this challenge, there is valuable resource recovery from water hyacinth which can be used to make financial and environmental returns. The visible differences between the control and utilisation methods lie in the definition, recognition, and matching of costs and benefits. Using a rapid appraisal of existing literature, which was analysed using meta-analysis, the current paper is an attempt to discuss the beneficial use of water hyacinth. It is argued in the paper that the economic feasibility of control methods which, on one hand, are used to calculate the economic value of water hyacinth, mainly relies on assumptions whose reliability and sustainability are questionable, thus implying limitations on using this kind of control methods. On the other hand, the costs and benefits of utilising water hyacinth can be quantifiable, making them susceptible to changes associated with time value and sensitivity analysis of possible fluctuations in cashflows. In the context of these annotations, other scholars have argued for the consideration of other utilisation alternatives, among which is included biogas which has been identified as the most viable option because of its potential in diversifying the energy mix, reducing greenhouse gas emissions, and contributing to improved water quality. Given these observations, this paper aims to contribute to policy and research discussions on the fiscal understandings of the material recovery from water hyacinth to promote the adoption of biogas technology. These views are discussed within the broader discourse of the sustainable development goals (SDGs). Full article

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17 pages, 365 KiB

Open AccessArticle

Waste Management in Australia Is an Environmental Crisis: What Needs to Change so Adaptive Governance Can Help?

by Stephen Jones

Sustainability 2020, 12(21), 9212; https://doi.org/10.3390/su12219212 - 5 Nov 2020

Cited by 25 | Viewed by 9278

Abstract

Research suggests that strengthening cooperation between governments is required to support improved policy outcomes. Despite established cooperative agreements between the levels of government in Australia, a lack of urgency and consistency continues to drive unsustainable approaches toward waste management practices. Adaptive governance has [...] Read more.

Research suggests that strengthening cooperation between governments is required to support improved policy outcomes. Despite established cooperative agreements between the levels of government in Australia, a lack of urgency and consistency continues to drive unsustainable approaches toward waste management practices. Adaptive governance has emerged as a potential approach for addressing complexity, with multiple actors collaborating in the design and implementation of challenging environmental issues. The main findings of this research highlight key challenges in multilevel systems and reforms required to establish institutional arrangements that support key adaptive governance enablers in the context of cooperative approaches to waste management. Full article

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20 pages, 3928 KiB

Open AccessArticle

Research Trends in the Economic Analysis of Municipal Solid Waste Management Systems: A Bibliometric Analysis from 1980 to 2019

by Rubí Medina-Mijangos and Luis Seguí-Amórtegui

Sustainability 2020, 12(20), 8509; https://doi.org/10.3390/su12208509 - 15 Oct 2020

Cited by 23 | Viewed by 4595

Abstract

This article analyzes state-of the art studies that focus on the economic aspects (EA) of municipal solid waste (MSW) management systems, including an analysis of articles that have developed methodologies for economic analysis (MEA), as well as those which study the economic analysis [...] Read more.

This article analyzes state-of the art studies that focus on the economic aspects (EA) of municipal solid waste (MSW) management systems, including an analysis of articles that have developed methodologies for economic analysis (MEA), as well as those which study the economic analysis of the externalities or external impacts related to these systems. The aim of this study was to determine the trends in research and critical points based on the literature available in the Web of Science database from 1980 to 2019. First, we present the statistics and general trends, then perform an in-depth bibliometric study using the VOSviewer software, which allows the results to be grouped according to references, authors, institutions, countries, and journals. The study showed that 563 articles about the economic aspects have been published, 229 about methodology development, and only 21 considered the methodologies for analyzing externalities generated by the MSW management systems. In general, there is great interest in the economic analysis of the systems and technologies that deal with transforming waste into energy. Full article

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15 pages, 4396 KiB

Open AccessArticle

Effect of Adding Drinking Water Treatment Sludge on Excess Activated Sludge Digestion Process

by Yanxia Wu, Haixia Du, Fusheng Li, Haoning Su, Sartaj Ahmad Bhat, Hudori Hudori, Maulana Yusup Rosadi, Faisal Arsyad, Yanqiu Lu and Huifang Wu

Sustainability 2020, 12(17), 6953; https://doi.org/10.3390/su12176953 - 26 Aug 2020

Cited by 9 | Viewed by 3603

Abstract

Drinking water treatment sludge (DWTS) is a waste by-product from water treatment plants where aluminum and iron salts are the most commonly used coagulants. DWTS was reused to investigate the effects of DWTS on the digestion liquid quality and microorganism activity of excess [...] Read more.

Drinking water treatment sludge (DWTS) is a waste by-product from water treatment plants where aluminum and iron salts are the most commonly used coagulants. DWTS was reused to investigate the effects of DWTS on the digestion liquid quality and microorganism activity of excess activated sludge (EAS). DWTS with four suspended solid (SS) concentrations (0%, 2%, 5% and 10%) was added to EAS which was sampled during aerobic and anaerobic digestion processes, then batch tests were carried out which followed the coagulation-flocculation process. It was found that DWTS can improve total dissolved nitrogen (TDN) and dissolved phosphorus (DP) removal efficiencies for anaerobic EAS. The highest removal efficiency of TDN (29.97%) as well as DP (55.38%) was observed when DWTS dosage was SS = 10%. The release of dissolved organic matter (DOM) by DWTS could increase dissolved organic carbon (DOC) concentration and lead to the accumulation of non-biodegradable humic acid-like substance in aerobic and anaerobic digestion liquid. The dehydrogenase activity (DHA) values of anaerobic EAS were higher than aerobic EAS. DWTS could reduce DHA for both EAS. These results indicate that potential risk of release of DOM should be considered when reusing DWTS in future research. Full article

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