Sustainability

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13 pages, 1912 KiB

Open AccessArticle

Adsorption of Tetracycline by Magnetic Mesoporous Silica Derived from Bottom Ash—Biomass Power Plant

by Phan Thi Hong Hanh, Khamphe Phoungthong, Suchada Chantrapromma, Patcharanan Choto, Chuleeporn Thanomsilp, Piyanuch Siriwat, Nuttachat Wisittipanit and Thitipone Suwunwong

Sustainability 2023, 15(6), 4727; https://doi.org/10.3390/su15064727 - 7 Mar 2023

Cited by 2 | Viewed by 1484

Abstract

In recent years, the contamination of the aquatic environment with antibiotics, including tetracyclines, has drawn much attention. Bottom ash (BA), a residue from the biomass power plant, was used to synthesize the magnetic mesoporous silica (MMS) and was utilized as an adsorbent for [...] Read more.

In recent years, the contamination of the aquatic environment with antibiotics, including tetracyclines, has drawn much attention. Bottom ash (BA), a residue from the biomass power plant, was used to synthesize the magnetic mesoporous silica (MMS) and was utilized as an adsorbent for tetracycline (TC) removal from aqueous solutions. The MMS was characterized by Fourier transform-infrared (FTIR), X-ray diffraction (XRD) pattern, and scanning electron microscopy (SEM). Optimum conditions were obtained in overnight incubation at 60 °C, a pH of 6–8, and an adsorption capacity of 276.74 mg/g. The isotherm and kinetic equations pointed to a Langmuir isotherm model and pseudo-first-order kinetic optimum fitting models. Based on the very low values of entropy changes (ΔS°), the negative value of enthalpy changes (ΔH°) (−15.94 kJ/mol), and the negative Gibbs free-energy changes (ΔG°), the adsorption process was physisorption and spontaneous. Full article

(This article belongs to the Special Issue Environmentally Sound Waste Management and Zero Waste Principles)

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16 pages, 1378 KiB

Open AccessArticle

Zero Waste Systems: Barriers and Measures to Recycling of Construction and Demolition Waste

by Lilliana Abarca-Guerrero, Susi Lobo-Ugalde, Nicole Méndez-Carpio, Rosibel Rodríguez-Leandro and Victoria Rudin-Vega

Sustainability 2022, 14(22), 15265; https://doi.org/10.3390/su142215265 - 17 Nov 2022

Cited by 6 | Viewed by 2781

Abstract

Urbanization, population growth, increased consumption, infrastructure, and housing needs are some of the factors that result in increased waste. Recycling has been a crucial way to reduce the amount of materials that end up in disposal sites and is how citizens, more aware [...] Read more.

Urbanization, population growth, increased consumption, infrastructure, and housing needs are some of the factors that result in increased waste. Recycling has been a crucial way to reduce the amount of materials that end up in disposal sites and is how citizens, more aware of the impacts on the environment, participate in some of the schemes to reduce waste. Zero waste is an approach developed to preserve the finite resources available, but major barriers are hindering its efficient and effective implementation. This study intended to unveil those barriers in the Costa Rican construction sector and to propose measures to increase the recycling rates. In order to achieve the objective, construction companies, cement producers, waste managers, personnel of refuse material facilities, waste transformers, construction material distributors, and a director of the Ministry of Health were interviewed to determine the challenges in the valorization of concrete, wood, metal, and packaging waste materials. This article reports the findings, which include, among others, the fact that most construction companies dispose the waste without any separation, except for metals. The cement producer companies do not participate in any form of collection system in spite of the available technology and equipment and the absence of innovative technologies for the transformation of materials. Full article

(This article belongs to the Special Issue Environmentally Sound Waste Management and Zero Waste Principles)

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17 pages, 9852 KiB

Open AccessArticle

Crushed Glass and Oil Extracted from Palm Oil Sludge as Primary Materials in the Production of Hydrophobic Sand for Capillary Barrier Applications

by Josefina Sullivan-Porras, María Badilla-Sánchez, Renato Rimolo-Donadio and Federico Masís-Meléndez

Sustainability 2022, 14(19), 12770; https://doi.org/10.3390/su141912770 - 7 Oct 2022

Cited by 1 | Viewed by 1339

Abstract

Hydrophobic-coated sand causes a reduction in infiltration, making it suitable for hydrophobic capillary barriers. Borosilicate glass waste was crushed into a synthetic sand 180 µm average, and fatty acids (PFA) were extracted from palm oil sludge. The synthetic sand was coated with PFA [...] Read more.

Hydrophobic-coated sand causes a reduction in infiltration, making it suitable for hydrophobic capillary barriers. Borosilicate glass waste was crushed into a synthetic sand 180 µm average, and fatty acids (PFA) were extracted from palm oil sludge. The synthetic sand was coated with PFA using mixing (POS-M) and solvent-assisted (POS-S) methods with stearic-acid-coated sand (SA) as a standard at concentrations varying from 1 to 16 g/kg. Contact angle measurements were undertaken by applying the sessile drop method. The water holding capacity of POS-M and SA were determined, and hydraulic conductivity curves were estimated with the van Genuchten model. Finally, a qualitative assessment of POS-M’s effectiveness as a capillary barrier was performed using a set of micro-tensiometers. Maximum contact angles for POS-M, POS-S, and SA were 119.73°, 118.83°, and 107.48°, respectively, and the saturated hydraulic conductivity of hydrophobized sands showed an exponential change of minus 2. Saturated conditions above the capillary barrier and unsaturated underneath were observed. In conclusion, the results indicate that the zero-waste approach applied through the reuse of solid waste from glass and palm oil production can be a waste management alternative in the production of hydrophobic sands that can be used in hydrophobic capillary barrier applications. Full article

(This article belongs to the Special Issue Environmentally Sound Waste Management and Zero Waste Principles)

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19 pages, 7867 KiB

Open AccessArticle

Effects of Silicic Acid on Leaching Behavior of Arsenic from Spent Magnesium-Based Adsorbents Containing Arsenite

by Hajime Sugita, Terumi Oguma, Junko Hara, Ming Zhang and Yoshishige Kawabe

Sustainability 2022, 14(7), 4236; https://doi.org/10.3390/su14074236 - 2 Apr 2022

Cited by 4 | Viewed by 1571

Abstract

The spent adsorbents left after treating arsenic-contaminated water contain large amounts of arsenic. These spent adsorbents may come into contact with silicic acid leached from soil or cementitious solidification materials in the disposal environment. Thus, it is important to evaluate the effects of [...] Read more.

The spent adsorbents left after treating arsenic-contaminated water contain large amounts of arsenic. These spent adsorbents may come into contact with silicic acid leached from soil or cementitious solidification materials in the disposal environment. Thus, it is important to evaluate the effects of silicic acid on spent adsorbents containing arsenic. In this study, the effects of silicic acid on spent Mg-based adsorbents (magnesium oxide (MgO) and magnesium hydroxide (Mg(OH)₂)) containing arsenite were investigated. The arsenic leaching ratios of both spent adsorbents decreased slightly with an increase in the initial silicic acid concentration of the eluent. The arsenic leaching ratio decreased from 1.24% to 0.69% for MgO and from 5.97% to 4.71% for Mg(OH)₂ at an initial Si-normalized concentration of 100 mg/L. The primary mechanism behind the inhibition of arsenic leaching by silicic acid was determined to be the difficulty of arsenic desorption due to the coating effect following the adsorption of silicic acid species. The results indicate that the arsenic leaching related to the ion exchange reaction with silicic acid hardly occurred for the spent Mg-based adsorbents. Compared with various spent Mg-based and Ca-based adsorbents, the spent MgO adsorbent exhibited the highest environmental stability and best performance. Full article

(This article belongs to the Special Issue Environmentally Sound Waste Management and Zero Waste Principles)

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22 pages, 4088 KiB

Open AccessArticle

Measurements and Modeling of Thermal Conductivity of Recycled Aggregates from Concrete, Clay Brick, and Their Mixtures with Autoclaved Aerated Concrete Grains

by Hong Nam Thai, Ken Kawamoto, Hoang Giang Nguyen, Toshihiro Sakaki, Toshiko Komatsu and Per Moldrup

Sustainability 2022, 14(4), 2417; https://doi.org/10.3390/su14042417 - 20 Feb 2022

Cited by 8 | Viewed by 2013

Abstract

Cool road pavements contribute to mitigating urban heat islands. To evaluate the heat balance in paved surfaces and to select appropriate road construction materials that help suppress heat islands, an accurate understanding of heat transport parameters such as thermal conductivity (λ) [...] Read more.

Cool road pavements contribute to mitigating urban heat islands. To evaluate the heat balance in paved surfaces and to select appropriate road construction materials that help suppress heat islands, an accurate understanding of heat transport parameters such as thermal conductivity (λ) and heat capacity (HC) is important. Recycled aggregates from construction and demolition waste, including scrap construction materials and industrial by-products, are often used for road construction; however, λ and HC of recycled aggregates especially for roadbeds are not fully understood. This study involved a series of laboratory tests to measure λ and HC of recycled concrete and clay brick aggregates (<40 mm) and their mixtures with autoclaved aerated concrete grains (<2 mm) under varied moisture conditions. The measured λ and HC increased with increasing volumetric water content (θ). Closed-form models for estimating λ(θ) were proposed using normalized thermal conductivity (λ_e) and effective saturation (S_e). The new λ_e(S_e) models performed well for the measured data compared to previously proposed models and would be useful to evaluate λ of recycled aggregates for roadbed materials. Full article

(This article belongs to the Special Issue Environmentally Sound Waste Management and Zero Waste Principles)

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18 pages, 3047 KiB

Open AccessArticle

Effects of Silicic Acid on Leaching Behavior of Arsenic from Spent Calcium-Based Adsorbents with Arsenite

by Hajime Sugita, Terumi Oguma, Junko Hara, Ming Zhang and Yoshishige Kawabe

Sustainability 2021, 13(23), 12937; https://doi.org/10.3390/su132312937 - 23 Nov 2021

Cited by 3 | Viewed by 1345

Abstract

The spent adsorbents that remain after being used to purify As-contaminated water constitute waste containing a large amount of As. These spent adsorbents, after being disposed, are likely to come into contact with silicic acid leached from the soil or cementitious solidification materials. [...] Read more.

The spent adsorbents that remain after being used to purify As-contaminated water constitute waste containing a large amount of As. These spent adsorbents, after being disposed, are likely to come into contact with silicic acid leached from the soil or cementitious solidification materials. Thus, it is crucial the evaluate the effects of silicic acid on spent adsorbents. In this study, the effects of silicic acid on spent Ca-based (CaO and Ca(OH)₂) adsorbents with arsenite were investigated. The As leaching ratio for the spent adsorbents decreased with an increase in the initial concentration of silicic acid in the liquid. Under the tested conditions, the As leaching ratio decreased from 8–9% to less than 0.7% in the presence of silicic acid at an initial Si-normalized concentration of 100 mg/L. The primary mechanism behind the inhibition of As leaching by silicic acid was determined to be re-immobilization via the incorporation of arsenite during the formation of calcium silicates. In the presence of silicic acid, spent Ca-based adsorbents with arsenite had a lower As leaching ratio than those with arsenate. Therefore, spent Ca-based adsorbents with arsenite were found to have a higher environmental stability than those with arsenate. Full article

(This article belongs to the Special Issue Environmentally Sound Waste Management and Zero Waste Principles)

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16 pages, 3080 KiB

Open AccessArticle

Steel Slag and Autoclaved Aerated Concrete Grains as Low-Cost Adsorbents to Remove Cd²⁺ and Pb²⁺ in Wastewater: Effects of Mixing Proportions of Grains and Liquid-to-Solid Ratio

by Gajanayake Mudalige Pradeep Kumara and Ken Kawamoto

Sustainability 2021, 13(18), 10321; https://doi.org/10.3390/su131810321 - 15 Sep 2021

Cited by 7 | Viewed by 2154

Abstract

This study investigated the applicability of industrial by-products such as steel slag (SS) and autoclaved aerated concrete (AAC) grains (<0.105, 0.105–2, 2–4.75 mm) as low-cost adsorbents for simultaneous removal of Cd²⁺ and Pb²⁺ in wastewater. A series of batch adsorption experiments [...] Read more.

This study investigated the applicability of industrial by-products such as steel slag (SS) and autoclaved aerated concrete (AAC) grains (<0.105, 0.105–2, 2–4.75 mm) as low-cost adsorbents for simultaneous removal of Cd²⁺ and Pb²⁺ in wastewater. A series of batch adsorption experiments was carried out in single and binary-metal solutions of Cd²⁺ and Pb²⁺ by changing the mixing proportions of SS and AAC grains. In addition, the effect of the liquid-to-solid ratio (L/S) on the removal of Cd²⁺ and Pb²⁺ in multi-metal solution was examined. Results showed that SS grains had a high affinity with Cd²⁺ in the single solution, while AAC grains had an affinity with Pb²⁺. In the binary solution, the mixtures of SS and AAC grains removed both Cd²⁺ and Pb²⁺ well; especially, the tested adsorbents of SS+AAC [1:1] and SS+AAC [1:4] mixtures achieved approximately 100% removal of both metals. Based on the results in the multi-metal solutions, the metal removal % and selectivity sequence varied depending on the mixed proportions of SS and AAC grains and L/S values. It was found that the SS+AAC [1:1] mixture of SS and AAC grains showed 100% removals of Cd²⁺, Pb²⁺, Cu²⁺, Ni²⁺, and Zn²⁺ simultaneously at L/S = 10 and 60. Full article

(This article belongs to the Special Issue Environmentally Sound Waste Management and Zero Waste Principles)

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29 pages, 5580 KiB

Open AccessArticle

Current Management Condition and Waste Composition Characteristics of Construction and Demolition Waste Landfills in Hanoi of Vietnam

by Hoang Giang Nguyen, Dung Tien Nguyen, Ha Tan Nghiem, Viet Cuong Tran, Akira Kato, Akihiro Matsuno, Yugo Isobe, Mikio Kawasaki and Ken Kawamoto

Sustainability 2021, 13(18), 10148; https://doi.org/10.3390/su131810148 - 10 Sep 2021

Cited by 19 | Viewed by 4062

Abstract

This study collected basic information and conducted waste composition surveys to identify the present management condition of construction and demolition waste (CDW) landfills in Hanoi of Vietnam and to characterize waste composition and grain size distribution of CDW dumped at landfills. Basic information [...] Read more.

This study collected basic information and conducted waste composition surveys to identify the present management condition of construction and demolition waste (CDW) landfills in Hanoi of Vietnam and to characterize waste composition and grain size distribution of CDW dumped at landfills. Basic information on seven CDW landfills under operation or closed/abandoned was collected, and the waste composition and the grain size distributions of dumped CDW at two landfills were investigated. Results showed that only one landfill site is currently under operation in Hanoi. Sanitary conditions of investigated landfills were relatively good without dumping of hazardous waste. Illegal dumping of domestic waste from residents, however, could be observed more or less at all sites due to an unclear boundary between dumping and surrounding areas. To improve current management of CDW landfills, a suitable recording system of accepted/dumped CDW and technical support for site managers are required as well as the implementation plan for developing and renovating landfills. Based on the results of the waste composition survey, the major components of dumped CDW were “Concrete”, “Clay bricks”, and “Soil-like”, and the sum of these materials reached >80% of the total. Grain size distributions of “Concrete” ranged from 10–600 mm and of “Clay bricks” ranged from 10–300 mm. Technical recommendations to examine a potential availability of dumped “Concrete” and “Clay bricks” as a base material in road construction are summarized from the viewpoints of segregation from “Soil-like” and impurities, grading of “Concrete” and “Clay bricks”, mechanical properties and environmental safety, and economic feasibility. The findings in this study raise challenges and perspectives to establish sound CDW management and to promote sustainable development of CDW recycling in Vietnam. Full article

(This article belongs to the Special Issue Environmentally Sound Waste Management and Zero Waste Principles)

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