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[en] Aquatic or land-based plastic pollution has raised serious concerns for ecosystems, and especially human and animal health worldwide. A variety of legislative instruments were developed to control, reduce, and manage the usage of plastics in day-to-day life to minimize the adverse outcomes brought by sending these plastic to landfill. Existing legislation heavily embraces levies, bans, and voluntary efforts through “reduce and reuse campaigns.” Thus, the present review highlights the pros and cons of the existing legislation and its implementation. It also assesses the need for the improvement of plastic legislation to better consider environmental and human health impacts. The paper proposes new efficient management strategies to aid in the development of plastic legislation which prevents increase of plastic pollution worldwide, the potential challenges that would arise from its implementation, and the mechanisms for overcoming these challenges. The paper proposes a conventional management strategy based on the current plastic management and legislation. It aims to improve the feasibility and effectiveness of the implementation of future plastic policies.
[en] For the understanding of contaminant transport and transformation through landfill liner soils, most models are proposed with one-dimensional solutions. However, for large-scale contamination analysis, the one-dimensional analytical equations are not valid owing to the restriction of contaminants moving in horizontal direction. Thus, semi-analytical solutions for two-dimensional transport and transformation of contaminants through soil media with the consideration of large-strain deformation have been developed. To achieve this, Gibson’s large-strain consolidation theory is applied to capture the deformation of soil media under loading, with self-weight effects being taken into account. Transport and transformation of dissolved or sorbed contaminates in fully saturated finite soil medias are captured by extending a well-developed advection-dispersion model in two-dimensional space. The proposed analytical solutions are validated through simulating the process of coupled transport-transformation process of contaminants and consolidation of a finite soil layer. Profiles of contaminant concentration for different cases have been compared and discussed. The resulting simulation shows that large-strain deformation would restrict the transport and transformation of contaminants significantly, in both horizontal and vertical directions. Parameter studies also indicate that, with the increasing depth of soil layer, the breakthrough time for contaminants increases dramatically; diffusion coefficients affect the two-dimensional distributions of contaminant concentration and fate of contaminant in layered soil significantly. The numerical findings of this study can provide proper suggestions for the design of landfill liners.
[en] The characteristics of Durio Zibethinus seed starch (DSS) that is used for landfill leachate treatment was investigated in this study. The DSS was extracted using dry milling (DM-DSS) and wet milling (WM-DSS) methods. The physico-chemical properties and surface morphology of the extracted starches were examined and analysed. Besides that, the efficiency of the extracted starch to remove colour, COD, suspended solid and turbidity were also evaluated and compared. Based on the results obtained, the WM-DSS showed better starch characteristics with high purity and smooth granule particles compared to DM-DSS. In addition, WM-DSS also recorded better leachate contaminants removal even at low dosage. Nevertheless, the performance of leachate contaminants removal for both extracted starch was very low. Thus, further chemical modification is required in order to improve the coagulation ability of the extracted starch. This finding indicated the potential of WM-DSS to be use as a coagulant aid for landfill leachate treatment. (paper)
[en] Highlights: • Little is known about FEW impacts of managing food waste after it has been disposed. • Food waste management options have variable FEW impacts and opportunities. • Preventable and unpreventable food waste have different mechanisms of FEW impact. • A “food-waste-FEW systems” approach may maximize benefits across FEW sectors. • Characterizing FEW nexus impacts of wasted food is a priority for future work. - Abstract: Throughout the world, much food produced is wasted. The resource impact of producing wasted food is substantial; however, little is known about the energy and water consumed in managing food waste after it has been disposed. Herein, we characterize food waste within the Food-Energy-Water (FEW) nexus and parse the differential FEW effects of producing uneaten food and managing food loss and waste. We find that various food waste management options, such as waste prevention, landfilling, composting, anaerobic digestion, and incineration, present variable pathways for FEW impacts and opportunities. Furthermore, comprehensive sustainable management of food waste will involve varied mechanisms and actors at multiple levels of governance and at the level of individual consumers. To address the complex food waste problem, we therefore propose a “food-waste-systems” approach to optimize resources within the FEW nexus. Such a framework may be applied to devise strategies that, for instance, minimize the amount of edible food that is wasted, foster efficient use of energy and water in the food production process, and simultaneously reduce pollution externalities and create opportunities from recycled energy and nutrients. Characterization of FEW nexus impacts of wasted food, including descriptions of dynamic feedback behaviors, presents a significant research gap and a priority for future work. Large-scale decision making requires more complete understanding of food waste and its management within the FEW nexus, particularly regarding post-disposal impacts related to water.
[en] Soil-bentonite (SB) backfill is used extensively in cutoff walls at landfill sites; the walls are used as engineered geotechnical barriers for contaminant control. With increasing bentonite content, the coefficient of consolidation and hydraulic conductivity of the SB decrease. However, when the bentonite content is increased beyond a certain percentage, the hydraulic conductivity of the SB decreases very little. One of the aims of this paper is to introduce the concept of optimal bentonite content (OBC) for SB cutoff walls, in which the hydraulic conductivity (kh) is expected to be lower than 1 × 10−9 m/s. Additionally, the paper introduces a new index consolidation stress ratio, cvσ′, which is used to obtain the OBC. For this study, the initial water contents of the SB backfill material are selected to be 0.8, 1.0, and 1.2 times their corresponding liquid limits. The clayey soils are amended with different bentonite contents, 0, 5, 8, and 10% (by dry weight basis) for the oedometer tests. Then, piezocone penetration test (CPTU) is applied in SB cutoff wall at a landfill site in Jingjiang city, China. The results of the laboratory and field studies show that the introduction of a new index, cvσ′, is very useful for calculating the OBC and for evaluating the coefficient of consolidation and hydraulic conductivity of SB backfill. The advantage of SB backfill with OBC is that it can achieve the design requirement of very low hydraulic conductivity and improve the safety reserves.
[en] Highlights: • Landfill modernization project in Nicaragua yields unintended consequences. • Enclosure of garbage site displaces hundreds of impoverished waste pickers. • Persistent social marginalization contributes to environmental degradation. • Sustainable development must incorporate concerns of informal waste pickers. - Abstract: The modernization (i.e. mechanization, formalization, and capital intensification) and enclosure of municipal solid waste management (MSWM) systems threaten waste picker livelihoods. From 2009 to 2013, a major development project, embodying traditional neoliberal policies with inclusive social policies, transformed the Managua, Nicaragua, municipal solid waste site from an open-air dump where as many as 2,000 informal waste pickers toiled to a sanitary landfill. To investigate waste pickers’ social and economic condition, including labor characteristics, household income, and poverty incidence, after the project’s completion, 146 semi-structured survey questionnaires were administered to four communities adjacent to the landfill and 45 semi-structured interviews were completed with key stakeholders. Findings indicate that hundreds of waste pickers were displaced by the project, employment benefits from the project were unevenly distributed by neighborhood, and informal waste picking endures due to persistent impoverishment, thereby contributing to continued social and economic marginalization and environmental degradation. The findings highlight the limitations of inclusive neoliberal development efforts to transform MSWM in a low-income country.
[en] A representative monitoring of groundwater quality is the basis for a reliable assessment of the impact of pollutant sources on groundwater. This is especially the case in the area around old closed landfills. A study of different methods of groundwater sampling was conducted at a municipal landfill site in Tychy-Urbanowice (southern Poland). The study compared the results of the electrolytic conductivity values obtained during vertical profiling both before and after purging with a passive bailer. The results obtained from the well volume approach after purging up to nine volumes of stagnant water in the piezometer were also taken into account, as were the results of the purging of water volume equal to the double volume of the filtered part of the piezometer. Particular attention was paid to the nested piezometers. The presented values confirm very large differences in the research results of both the sampling technology and the depth of sampling, the piezometer construction and its lithological profile and in the duration and intensity of the tests carried out. In order to determine the real-time variability of the contamination of the monitored water, the tests should be carried out in the same way and should use a fixed schedule.
[en] Flow slides are relatively common environmental disasters that occur in municipal solid waste (MSW) landfills and can result in serious consequences in surrounding regions. This study presents experimental and numerical investigations into the constitutive flow behavior of a MSW stimulant at post-failure stage. First, a series of ring shear tests on MSW simulant are conducted under varying shear rates; the residual shear strength is observed to grow linearly as the shear rate increased, which behaves like a kind of viscous fluid. Based on the results, the concept of viscosity coefficient is introduced and a viscous fluid model is established to describe the constitutive behavior of the MSW simulant at post-failure stage. This model is finally incorporated into a smoothed particle hydrodynamics (SPH) code to simulate a flow slide model test. The numerical results agree well with the test data, thus verifying the applicability and reliability of the viscous fluid model to describe flow slide disasters in landfills.
[en] The stabilization of severely As-polluted soil has been a challenge, especially for the extremely toxic As(III) contaminants. In this study, soil with a high As concentration (26084 mg/kg) was availably stabilized by a H2O2 pre-oxidation assisted TMT-15 (Na3S3C3N3 solution with a mass fraction of 15%) and FeCl3·6H2O stabilization method. The results showed that the combination of the two stabilizers (i.e., TMT-15 and FeCl3·6H2O) presented a better stabilization behavior than either stabilizer used individually. The use of the H2O2 pre-oxidation assisted TMT-15 and FeCl3·6H2O stabilization approach not only converted the As(III) to As(V) but also reduced the toxic leaching concentration of As to 1.61 mg/L, which is a safe level, when the additions of TMT-15 and FeCl3·6H2O were 2 mL and 0.20 g, respectively. Thus, using only a simple H2O2 pre-oxidation to combine clean stabilization with non-toxic stabilizers TMT-15 and FeCl3·6H2O could render the severely As-contaminated soil safe for disposal in a landfill.
[en] Eggshells wastes are produced in huge amounts worldwide. The recycling or valorization of this waste, which otherwise is usually disposed in landfills, represents an opportunity within a circular economy perspective. In the present work, the potential of chicken eggshell waste to produce calcitic lime was explored. After collection from an industry supplier, the waste was thoroughly characterized for its mineralogical, chemical, and thermal properties. The material was calcined at 1000 °C, and the obtained calcium oxide was evaluated for its reactivity in wet slaking tests. Comparison was made with commercial limestone used as reference. It was found that the calcium oxide from eggshell waste belonged to the most reactive class (R5—60 °C within 10 min), the same of the calcium oxide from limestone. However, different times were obtained to reach 60 °C (25 s and 4:37 min:s) and for 80% of the reaction (28 s and 5 min) for calcium oxide from limestone and eggshell waste, respectively. The lower reactivity of calcium oxide from eggshell waste was related to its larger size particles with smoother surfaces and lower specific surface area in comparison to limestone calcium oxide. Industrial, environmental and economic implications concerning the use of this waste to produce lime were also evaluated. The eggshell waste could be all consumed at an industrial scale in Portugal allowing for approximately 2.6% partial substitution of limestone in a lime factory.