جستجوی مقالات مرتبط با کلیدواژه "landfill" در نشریات گروه "عمران"

The increase in the urban population and the change in the consumption pattern in recent decades has caused the per capita volume of produced waste to increase significantly. The introduction of a large number of urban waste materials along with thousands of tons of dangerous toxic substances and hospital and industrial waste materials into the environment creates many problems that have harmful effects on other existing systems. urban and including their environmental system is remarkable. Finding a suitable place for waste disposal is one of the most important study steps in parallel with landfill design, whose management plays a significant role in environmental positioning because of the lack of attention to environmental and management studies in the planning process. Urban planning, especially in terms of landfill location, leads to problems such as flooding, leachate infiltration into underground water, soil and surface water pollution, placement on unstable land, and topological problems. In the Bandar Abbas, about 500 tons of waste is produced daily, which is collected in an unsanitary manner, collected, transported and buried in front of the railway station, which causes the spread of pollution in the region. For this reason, in the present study, an attempt has been made to locate the best landfill site to achieve this approach, 4 environmental criteria (6 sub-criteria), ecological (5 sub-criteria), structural (11 sub-criteria) and Physical (7 sub-criteria) was used. These criteria were weighted by ANP. After preparing the Euclidean distance map and combining it with fuzzy operators for each sub-criterion, the resulting map was multiplied by the ANP fuzzy weight. Then, fuzzy operators AND, OR, SUM, Product and gamma of 0.9, 0.7 and 0.5 were used to overlap the layers. OLS regression was used to select the best superimposed map. Finally, the TOPSIS was used to rank the selected sites and the best site. The results showed that the ecological criterion with a fuzzy weight of 0.443 has the greatest effect on the location of landfills. After that, structural, environmental and physical criteria were placed in the next ranks with 0.278, 0.182 and 0.095, respectively. In ecological sub-criteria, the distance from the sensitive habitat of Mount Gnu with 0.438; In structural sub-criteria, the distance from settlements with 0.155; In the environmental sub-criteria, the distance from the canal with 0.283 and in the physical sub-criteria, the distance from the river with 0.310 have the greatest effect on the location of landfill. Among the fuzzy overlay operators, the SUM fuzzy subscription operator has the highest correlation with the research criteria in identifying the landfill. Five landfill sites were identified in Bandar Abbas, and with the TOPSIS ranking model, District 4, located west of Bandar Abbas and Tel Siah village and east of Bandar Abbas, a 15 km2 of land was selected for landfilling of urban and industrial waste.

According to the estimations, about 80% of municipal and rural solid waste in Iran is disposed in landfills. This rate is similar to some countries like Greece or Croatia in Eastern Europe. However, there is a pivotal tendency, particularly among industrialized and developed countries like Germany, Japan, Belgium and Netherlands, to reduce the rate of landfilling solid wastes less than 1% through the recycling, composting and reuse (EEA, 2016). The European Union has set 10% as its vision for limiting the rate of solid waste landfills by 2035. Despite the will of reducing solid waste landfills worldwide, its application is inevitable, particularly in developing countries like Iran. Therefore, spatial analysis and zoning safe areas is the primary step for protecting the environment against the pollutions in these sites.In the last decade, there are quite numerous researches that aimed on optimizing the location of landfills through the combination of multi criteria decision making and spatial analysis tools, like geographic information systems (GIS) (Özkan et al. 2020; Şimşek and Alp, 2022). However, they were usually confined to a city area, used a few criteria, and emphasized to specific case studies. This conventional approach can highlight the locations where landfills might have the least environmental risks in a small scale. In addition, the accumulation of these researches can highlight some critical criteria and geographic layers. Although, we believe that in larger scales, optimizing the locations of landfills should be finalized by detailed quantified environmental impact assessment, like life cycle assessment (LCA) (Kumar et al. 2020). Prior to any technical decisions, a spatial survey is required to filter the risky regions for zoning landfills.This study uses GIS tool with 70 layers and criteria to classify the large area of Isfahan province, centre Iran, into risky and safe zones. Accordingly, the status of existing 210 solid waste landfills, disposal stations, and facilities are checked based on national guidelines and regulations. Here, the states and cities with the highest environmental violations are highlighted.

With the population growth, technological advancement, and the increase in heavy metal pollutants, besides the location of a quarter of the earth's surface in cold regions, it is necessary to study the effect of freeze-thaw cycles on clay and predict its behavior over time. The effect of freeze-thaw cycles on the behavior of clay contaminated with heavy metals has been less studied. In addition, low plasticity clay and shale sedimentary rock are frequent in Iran. As an innovation in this article, the effect of the freeze-thaw cycles on the compressibility behavior of shale-clay soil in the presence of lead and zinc heavy metal pollutants is investigated. The combination of low plasticity clay with 40 and 60% crushed shale was investigated. For this purpose, 60 one-dimensional and Atterberg limit tests were conducted on the samples in the presence of 0, 5 and 25 cmol/kgsoil of lead nitrate and zinc nitrate pollutants. According to the obtained results, the most changes in liquid limit are related to the samples contaminated with 25 cmol of lead nitrate after 12 cycles of freeze-thaw cycles with a 43% reduction. And the lowest changes in liquid limit are related to the combination of 40% kaolinite with 25 cmol of zinc nitrate pollutant. Also, the results obtained from the consolidation test indicate that the compressibility of the samples was affected by the concentration of lead and zinc heavy metal pollutants and the freeze-thaw cycles. The increase of heavy metal pollutants led to a decrease in the initial void ratio and compressibility index of the samples compared to freeze-thaw cycle, which led to an increase in these ratios. The maximum changes were made in the first four cycles of the freeze-thaw cycle, and the changes were insignificant until the 12th cycle.

Unscientific waste control and using inflamed masks and gloves in municipal garbage represent a risk of an outbreak. Furthermore, in growing nations, pollutants of the surroundings and groundwater have raised the call for landfills to decrease pandemic risk. Alternatively, municipal strong waste landfill barrier structures regularly contain an aggregate of geosynthetics and mineral layers. Throughout the last 20 years, there were full-size studies on the interactions among the substances and on the overall performance of the geosynthetics consisting of components of durability. This study has led to giant advances in the layout and specification of landfill lining structures. Although many numerical modeling applications are implemented to assess lining system stability and integrity, records to validate those models are presently limited. This paper highlights the records required to validate numerical models and instrumentation strategies that can be used to accumulate this information imposed at the liner (stress cells). The use of numerical analysis to analyze the stability and integrity of landfill liner systems has increased popularity over the last three decades. Internal landfill pressures, on the other hand, are emphasized by the majority of them. The presence of water flows behind the landfill side slope was investigated in four height level codes. The results are compared to on-site landfill data in order to validate the numerical model. This case study is the Miligate dump in the United Kingdom. The Finite Element (FE) model in three dimensions is used. To improve the accuracy of the study, the interfaces and properties of the materials were chosen from the experimental results. The findings revealed that a lining system with a water level up to 3/4 of the side slope was immune to failure, but that when the side slope was filled with respect to the full height, the geomembrane would be ripped.

In recent years the rupture of landfill centers has resulted in the importance of studying the behavior of municipal solid waste (MSW). MSW as the main constituent element in landfills has a complicated performance. In this study, by using the results of large –scale direct shear experiments with dimensions of 300 mm x 300 mm x 150 mm, 2 models to predict the behavior of MSW with ages of fresh and 3 months are presented. The purpose of this investigation is to predict MSW stress-strain behavior for kahrizak landfill as a sample of developing countries landfills under aging and by structural models. These models are Hyperbolic model and Evolutionary polynomial regression (EPR). In these collection of experiments, aging process up to 3 months, was artificially applied to samples. Three normal stresses 20, 50,100 kpa and three shear strain rates 0.8,8,19 mm per minute were used for samples with different ages. The results of these two models, in addition to predict MSW behavior under aging and degradation, shows high accordance with experimental results by direct shear apparatus. Finally this study states the advantage of EPR model relative to Hyperbolic model in higher accuracy for all experiments.

Soils contaminated with heavy metals are among the common environmental geotectonic problems all around the globe. Clay is considered as one of the best protective layers for environment to absorb polluters. Considerable SSA, very low permeability and the clays cationic capacity have been good factors to use these materials in geo-environmental projects vastly. It can react with the materials existing in the polluters because of the layered structure and special vast surface so the clay can absorb all or some of the dangerous polluter materials passing through the soil. Each part of the mineral materials constituting the clay, carbonate, organic materials, oxides, amorphous materials or remained phases can play a role in the process retention heavy metals. Carbonates play a special role in the process of the clay and metallic polluters’ interaction. The effect of the soil structure in retention heavy metal has been studied in many researches. In geotechnical environment view the clay mineral montmorillonite is one of the clays used in geo-environmental projects. Among the clay minerals montmorillonite has the highest property absorbing polluters. In the absence of clayey soils, compacted bentonite-enhanced sand mixtures are attracting greater attention as suitable material for contaminant barrier systems. The efficiency of these insulated barriers depends largely on their hydraulic and mechanical behavior. In landfills, as the main function of the liner is to minimize the movement of water out of the waste disposal facility, Landfill should satisfy three performance criteria if it is to perform satisfactorily as a barrier material. It should have low hydraulic conductivity (typically less than 1×10-9 m/s), should have sufficient strength in order to be stable during construction and operation, and it should not be susceptible to excessive shrinkage cracking due to water content changes that usually occur during the lifetime of the landfill. On the other hand, provision of the proper platform for landfills has been a concern of geotectonic and environmental geotectonic researchers in the past three decades. One of the objectives of this research was to introduce a material with suitable environmental geotectonic properties, minimum permeability, and maximum contaminant absorption potential. The process of producing nanoclay particles from bentonite clay with a top-down approach involves omission of some materials in the form of tailings. In related studies, the bentonite clay sample was divided into the following two main parts through physical and chemical processes: nano-montmorillonite (SLB) and process tailings (BLB). In this research, through a series of geotectonic and environmental geotectonic experiments the interaction of nano-montmorillonite interaction (SLB), process tailings (BLB), and bentonite clay samples with heavy metal contaminants was studied and analyzed experimentally. It shall be mentioned that the process of separating bentonite clay sample components was analyzed through microstructural X-ray diffraction (XRD) and specific surface area (SSA) experiments as well as scanning electron microscope (SEM) imaging. The tests conducted in the study were mostly on the basis of ASTM standard and the geo-environmental tests directions issued by McGill University of Canada. The soil carbonate percentage was defined by titration method. The specific surface area (SSA) was determined using the ethylene glycol-monoethyl ether (EGME) method. CEC was determined by the BaCl2 replacement method. The carbonate content of the soil was determined by titration, and the soil pH was measured in 1:10 soil solution.Also the soil pollution retention capacity was measured by titration test and HNO3 in different concentrations was added to the samples. Results of the present research suggest that process tailings (BLB) contain approximately 80% of copper as a heavy metal contaminant at a concentration of 100 cmol/kg-soil. In addition, permeability of the BLB sample and its inflation are approximately 5.2 10-10 m/sec and 70%, respectively.

The rapid increase of urban population and waste production is one of the most important environmental problems in developed and developing countries. Million of tons of waste material are produced annually in the world, the correct disposal and management of which presents a main concern in the human societies. With the increase in population, and industrialization of societies accompanied by economic growth, the production of waste material has increased throughout the world. It is predicted that the population of the world will increase 2 to 3 Milliard people in the next 30 years. This means that urban waste material production will increase 3 to 4 times. Along with health and environmental adverse effects of the landfill site, emissions of carbon dioxide, the intensification of the process of global warming on a global scale also will follow. Absence appropriate supervision over management and accumulation of these outputs can engender many environmental problems, especially for people who live near the landfill to be followed. Thus, appropriate urban landfill site selection is a main issue related to the stability of cities and human environments. Geographical information systems (GIS) have appeared as useful, computer-based tools for the spatial operations like entry, storage, manipulation, analysis, and display of geographical data. Since GIS can manage a large amount of spatial data, it can serve as an ideal tool in the siting studies. In addition to the use of GIS in the landfill site selection studies, multi-criteria evaluation method to deal with the issues that decision makers and experts face with in landfill site selection is used. Combination of GIS and multi-criterion evaluation method provides a valuable tool for the solution of landfill site selection problems. In this study, fuzzy logic based on Weighted Linear Combination (WLC) were used for urban waste landfill site selection in Arak city in ARC GIS 10.1 software environment with respect to the ecological, and socio-economic parameters.
In this research, reviewing the international obligations in landfill site selection and using environmental expert views on weighting the effective ecologic, and socio-economic criteria in landfill site selection it was revealed that ecologic sub-criteria, including depth of groundwater resources, distance from surface water resources, and flood potential were of great importance in urban landfill siting. Moreover, among the socio-economic sub-criteria, distance from rural and urban population centers were vital in urban landfill site selection. In the present study, after the production of the final suitability map with fuzzy logic based on WLC, the spatial desirability was divided into 5 classes. The spatial desirability for landfill sites lies in the fuzzy membership degree of between 0.3 and 0.87. Around 11033 polygons with an area of 4146.03 square kilometers were found whose spatial suitability in the fuzzy membership degree of 0.3 to 0.87. The most spatial suitability lie in the fuzzy membership degree between 0.69 to 0.87. The spatial suitability of these areas with their fuzzy membership degree is as follows: very low suitability with the fuzzy membership degree of 0.3 to 0.47, low suitability with the fuzzy membership degree of 0.47 to 0.56, moderate suitability with the fuzzy membership degree of 0.56 to 0.63, high suitability with the fuzzy membership degree of 0.63 to 0.69, and very high suitability with the fuzzy membership degree of 0.69 to 0.87. The area of the existing polygons and their number are as follows: very low suitability polygons with the area of 270.73 km2 and number of 328 polygons, low suitability polygons with the area of 683.48 and number of 1687 polygons km2, moderate suitability polygons with the area of 1187.02 km2 and number of 3006, high suitability polygons with the area of 1212.44 km2 and number of 3954 polygons, very high suitability polygons with the area of 792.36 km2 and number of 2058 polygons.

Shear strength of landfill municipal solid waste (MSW) is a more important topic in landfill stability investigation. Impressibility of this material from the temperature and humidity regarding to its early component cause that this material suffering much change in its shape. This variation with filling condition such as prime compression and soil increasing for daily and monthly cover change structure of MSW; so the fresh samples or primary component have not enough indication to define the problem. In this paper, large-scale direct shear tests were performed on the real samples with different age and different percent of soil obtained from Alborz landfill in Qom city to investigate shear strength of materials in existing landfill and to expand the landfill. Other parameters such as overconsolidation and plastic content have analyzed. The results shows that shear strength have decreased with increasing in waste age and plastic content. In addition, with changing in soil amount to optimum percent shear resistance increased and then decreased. Overconsolidation without changing in compaction effort has mutated the mobilization of shear strength.

1. The use of marble rock flour residue was investigated in the laboratory for the potential use as a landfill liner material. The clayey soil, sand, and cement were used as the additives. The rock flour and the additive material were mixed, compacted, and tested for diffusion and the hydraulic conductivity. The obtained diffusion coefficients were compared with the recommended diffusion coefficient for a compacted clayey liner. The comparison showed that the mixed material containing 65% rock flour and 35% clayey soil is acceptable with regard to diffusive transport mechanism compared to other mixed materials. The hydraulic conductivity was determined by the flexible wall triaxial hydraulic conductivity apparatus and the value of 1.210-10 m/s was obtained for this mixed material. This amount of hydraulic conductivity is in the range of values recommended for the compacted clayey liners and therefore this material is acceptable in terms of advective transport. The results showed that the diffusion coefficient and the hydraulic conductivity of the compacted mixed material containing 65% marble rock flour and 35% clayey soil are in the range of the recommended values for the compacted clayey liners.2. Methodology2.1. The marbel rock flour, clayey soil, sand, and cement were used as the materials for this study. These materials were mixed in different percentages to obtain three types of mixed material. The type 1 mix included 67% rock flour, 27% sand, and 5% clayey soil. The type 2 mix included 65% rock flour and 35% clayey soil. The type 3 mix included 90% rock flour and 10% cement. The 100% pure rock flour was also tested. The material were compacted in a polyethylene tube and were tested for chloride ion diffusion coefficient. The mixed material type 2 was tested for the hydraulic conductivity.2.2. Theoretical modeling: The program POLLUTE [1] was used for the prediction of the chloride diffusion coefficient in the tested material based on the observed chloride concentrations data. The following diffusion coefficients were obtained: 5.310-10 m2/s for pure rock flour, 810-10 m2/s for type 1 mix, 5.510-10 m2/s for type 2 mix, and 710-10 m2/s for type 3 mix. 3. Results and discussion3.1. Diffusion: The comparison of the results for chloride diffusion coefficients showed that the mix material type 2 has the lowest diffusion coefficient. This material has 30% clayey soil which gives the mixture enough absorption capacity as a liner material [2]. Thus, type 2 mix material is found to be suitable as a liner material in the landfill applications compared to two other mixed material. Fig. 1 shows the observed and predicted concentration profiles for type 2 mix material.3.2. Hydraulic conductivity: The type 2 mix material was tested for the hydraulic conductivity using the flexible wall hydraulic conductivity apparatus. The hydraulic conductivity value of 1.210-10 m/s was obtained for this material.4. The type 2 mix which included 65% rock flour and 35% clayey soil materials resulted in a reasonable low diffusion coefficient of 5.510-10 m2/s which is in the range of the reported diffusion coefficients for the compacted landfill liner material. The resulted hydraulic conductivity of 1.210-10 m/s for this mix material is also acceptable and is in the range of the standard value for the compacted landfill liner material. Thus, the type 2 mix is recommended as an alternative liner material for solid waste landfill liner applications.

The role of unsaturated drainage layer and hydraulic control systems in sanitary-engineered solidwaste landfills were simulated using three-layer one-dimensional laboratory models. In the models,from top to bottom, a sodium chloride solution as a contaminant source reservoir, a first compacted siltlayer as a primary liner, a coarse sand layer as a secondary leachate collection system or a hydrauliccontrol layer, a second compacted silt layer as a secondary liner, and a bottom water reservoir as agroundwater aquifer, were used. In the first two tests, the model simulated the secondary leachatecollection system and natural hydraulic trap system (upward flow through the second clayey siltlayer). In this case, the contaminant transport mechanisms through the first silt layer were downwardadvection and diffusion, and through the second silt layer, diffusion was downward and advection wasupward. The results showed that the implementation of the natural hydraulic control system couldeffectively reduce the contaminant transport to the underlying groundwater reservoir. In the third test,the natural and engineered hydraulic trap systems were simulated (upward flow from the bottomreservoir to the upper reservoir). In the fourth test, the model simulated the engineered hydraulic trapsystem (downward flow through the first silt layer and upward flow through the second silt layer). Theresults showed that natural and engineered hydraulic trap systems have important effects on reducingthe contaminant transport toward the underlying aquifer. In all experiments the chloride concentrationin silt and coarse sand layers and top and bottom reservoirs were measured and the observedconcentrations were compared with theoretical concentrations calculated by computer code POLLUTEV6. The results showed that there is good agreement between theoretical and observed data.