Waste Layer Research Articles

Advanced ERT techniques for methane potential evaluation in controlled dump sites: A forward modeling approach

Methane (CH4) emissions from large controlled dump sites play a significant role in global warming. However, when captured efficiently, CH4 is a valuable energy resource. This study optimizes electrical resistivity tomography (ERT) for improved CH4 detection in controlled dump sites, focusing on refining electrode array configurations. We assessed three configurations: dipole-dipole, Wenner-Schlumberger (WS), and Wenner arrays. The results were compared with synthetic data simulated using the forward modeling technique, and the model's accuracy was evaluated using the Nash-Sutcliffe model efficiency coefficient (NSE), model sensitivity, and root mean square error (RMSE). Additionally, we analyzed the model's correlation with CH4 flux measurements. The WS array demonstrated the best performance, achieving a lower RMSE (23.4 %), a higher NES (0.90), and model sensitivity (0.90), along with a moderate negative correlation (-0.50) with CH4 flux measurements. This configuration effectively identified subsurface features, such as organic waste layers and leachate zones, which are crucial for CH₄ capture and landfill gas collection. Forward modeling confirmed the WS array's ability to provide high-resolution subsurface imaging, enhancing CH₄ hotspot detection. By improving the spatial and temporal accuracy of CH₄ detection, this approach addresses limitations in traditional methods and supports the design of more efficient gas capture systems. Applied in Thailand, these findings highlight the potential of optimized ERT techniques for enhancing CH₄ recovery in waste-to-energy systems, contributing to more sustainable waste management practices and reducing greenhouse gas emissions.

Synergetic enhancement of moisture-electric generation through interfacial evaporation and active electrode

Ion migration-based moisture-electric generator holds the open-circuit voltage to power portable electronics, the Internet of Things, and wireless transmission. However, most devices still encounter challenges with the attainment of high-density power generation in continuous mode. Here, we introduce a sustainable and high-power density ion-selective bipolar moisture-electric generator that relies on Au-Al electrodes, capillary water supply, and interfacial evaporation. The device generates electricity by exploiting the salinity gradient between the capillary waterways in the photothermal and waste heat layers. This process is synergized by electrochemical reactions of the electrodes, which propel the migration of cations and anions through ion-selective bipolar hydrogels toward the intermediate waterway. It demonstrates a short-circuit current density of 52.2 A m−2 and a power density of up to 33.8 W m−2 over 0.5 cm × 0.5 cm electrodes. Connecting 13 devices in series in darkness successfully illuminates an LED lamp with a rated power of 1 W together with an operating voltage of 2.0–2.8 V. This work offers an off-grid, environmentally friendly, and affordable solution for high-density moisture power generation.

INTEGRATED TECHNOLOGY OF BIOGAS UTILIZATION OF SOLID HOUSEHOLD WASTE LANDFILLS WITH THE PRODUCTION OF ELECTROCITY, HEAT AND CARBON DIOXIDE

The presence of carbon dioxyl as a non-combustible admixture in the landfill biogas of solid household waste and the absorption of ambient air into the layer of landfill waste, and therefore its entry into the landfill gas, significantly reduces the concentration of methane in it, which affects the efficient operation of the gas piston engine of the power plant and the reduction of volumes electricity generation. With the use of computer modeling for the composition of biogas with an increased content of N2 and a reduced concentration of CH4 £ 32 %, calculations were made on the enrichment of biogas to concentrations of CH4 in it of 36–44 % due to the use of CO2 amine absorption technologies, in which the costs for the regeneration of the absorbent are compensated by the produced thermal energy of the gas piston engine of the power plant. The removal of carbon dioxide from biogas makes it possible to simultaneously increase the concentration of methane in it at the input to the heat engine, which contributes to the stable and efficient operation of the gas piston engine of the power plant and the increase in the amount of electricity generation as a result of energy utilization of landfill gas. The use of complex biogas utilization technology in the cogeneration mode allows obtaining not only electricity, but also heat, which can be used in absorption amine technologies for CO2 extraction from biogas and thus reducing carbon dioxide emissions into the atmosphere. Bibl. 17, Fig. 9, Tab. 3.

Effect of humic acids extracted from different organic sources and inoculation with Bacillus subtilis or Aspergillus Niger on urease activity in calcareous soil

Humic substances have received a large share of research and development as amendments to poor fertility soils that are poor in fertility and have deteriorating physical properties, since the process of extracting is a common process and easy to implement, as well as diluting these acids with water enables them to be used at economically acceptable levels over large areas. It is necessary to noticed that the properties of these acids depending on the organic source and the concentration added to the soil. A laboratory experiment was conducted at the Department of Soil Sciences and Water Resources, College of Agriculture, University of Basrah ,IRAQ to demonstrate the effect of humic substances extracted from different sources and inoculation with Bacillus subtilis or Aspergillus niger on the activity of the urease in calcareous soil. Wheat straw, alfalfa leaves, goat waste and poultry waste were composted aerobically for 3 months by filling a hole of 2×2×1.5 m by layers of such waste ,turned weekly for aeration. Each pile was extracted for humic acids (humic acid + fulvic acid) . Humic acid mixed with to soil at levels of 0, 25, and 50 L h-1. The soil was also inoculated with Bacillus subtilis or Aspergillus niger isolated from local soil at rates of 20.06×106 and 40× 103 cfu ml-1, respectively The samples were incubated at field capacity level 28±2°C for 30 days. Urease activity was estimated after 7 or 30 days by determining NH4+ released using steam distillation method . A decrease in urease activity was observed when treated with different types of humic acid compared to the control treatment. The lowest activity was obtained at humic acids extracted from poultry waste, reaching 312.0 and 188.72 µg N-NH4+g-1soil.2h-1 at incubation periods of 7 and 30 days, respectively .The results also indicated that increasing the level of humic acids significantly inhibited the activity of the enzyme. However, in soil treated with Bacillus subtilis or Aspergillus niger, an increase in urease activity was observed compared to the non-inoculation treatment. Treatment with the fungal inoculant had higher activity than the bacterial inoculum, reaching 324.5 and 297.2 µg N-NH4+ g-1 soil 2 hours-1 for both inoculants at a period of 7 days, and 178.09 and 150.31 µg N-NH4+g-1soil.2h-1at a period of 30 days, respectively.It is proposed that the inhibition of urease by humic acid addition may benefit for increasing urea fertilizer efficiency.

Physico-mechanical parameters of rock materials used in open pit reclamation – a case study of CTL Maczki-Bór S.A. mine in Poland

The aim of the research was to assess the variability of selected physical and mechanical properties of Carboniferous barren rocks in the Upper Silesian Coal Basin and to analyze the impact of time and increasing vertical pressure on the mechanical parameters of the mixture of these rocks used in the reclamation of the open pit. Both type of tests were conducted in a strength press. For lithologically and stratigraphically differentiated rock samples, strength parameters in various states of humidity (air-dried and capillary saturation state) were determined, including compressive strength, cohesion and the angle of internal friction. It was found that the strength of all types of rock increases with geological age, however saturation of these rocks with water causes their structural weakening, which is especially noticeable in the case of sandstone and claystone. In the case of mudstone, due to their structure, the reduction of strength after saturation with water is not so significantly noticeable. In the second part of the laboratory tests, 5 samples of Carboniferous post-mining waste with different storage times in the open pit were subjected to the assessment of changes in density and compressibility in relation to increasing values of vertical pressure. It was found that the long-term depositing of waste in the excavation is conducive to the intensive development of hypergenic processes. This contributes to the disintegration of sedimentary rocks, which causes changes in their physical and mechanical parameters. This phenomenon is additionally intensified by the increasing vertical pressure with thickness of waste layers.

Numerical model for simulating the hydraulic parameters of the aeration system ensuring equal oxygenation of the compost heap

The aim of the work was to develop a mathematical model using equations of fluid mechanics that describe the dynamics of air flow in a part of the compost aerating system integrated with a stationary reactor. The results of the simulation show that adjusting the flow resistance along the entire length of the compost aerating duct, depending on the distance from the connection of the duct with the fan's pressure conduit pipe through gradually increasing the air outflow area by increasing the number of repeatable gaps, yields a uniform pressure distribution above the grate. The process parameters used for computation were relevant to composting a subscreen fraction separated from mixed municipal waste using 80 mm mesh screen (Fr<80 mm) under real conditions. Microsoft EXCEL 2010 software and STATISTICA version 13.3 by StatSoft were used for numerical and statistical analysis of the test results. The research results are presented in four tables and five figures and discussed in the text of the article. During tests performed in real conditions, various variants were tested for reactor filling level and air outflow active surfaces in subsequent grate parts (Fc (i)). It was found that the target waste layer thickness i.e. 3.0 m and Fc (i) changes, in accordance with the values of the developed model, result in a stable pressure distribution pd, amounting to 1506 Pa and 1495 Pa at the grate front and end part.

The potential of Municipal Solid Waste (MSW) layers as Anthropocene strata

The potential of Municipal Solid Waste (MSW) layers as Anthropocene strata

Effectiveness of the adsorption properties of clay in relation to the disposal of organic waste from poultry farms

This article discusses an important problem related to the disposal of organic waste from poultry farms. Bird droppings are one of the main sources of environmental pollution and consume significant resources for disposal. The search for effective and environmentally safe methods of disposal of such waste is very relevant. The article focuses on the study of the adsorption properties of a clay accumulation site. Due to the insufficient knowledge of this technology of manure burial, full-scale modeling was performed to determine the effectiveness of protecting the components of the ecological and geological environment. It is shown that under conditions of complete water saturation, the liquid fraction from the organic waste layer will easily seep through the voids and cracks of the clay layer and poison the underlying soils and groundwater. It is concluded that a clay special site alone does not provide guaranteed environmental safety of the environment. Engineering and environmental recommendations are given on the mandatory combination of this method of burial of litter with a litter made of a layer of sealed film coating.

Qualitative and quantitative characterization of waste layers fed diets containing mineral sources and rosemary oil levels

Resumo Realizou-se este estudo com o objetivo de avaliar fontes de minerais e de níveis do óleo de alecrim na dieta de poedeiras comerciais sobre as características qualitativas e quantitativas dos dejetos gerados. Os dejetos foram provenientes de 288 poedeiras comerciais da linhagem HyLine Brown (poedeiras semipesadas) com 30 semanas de idade, durante o período de 112 dias (4 ciclos de 28 dias). Foi utilizado delineamento inteiramente casualizado com esquema fatorial 2x3 com medidas repetidas no tempo (16 repetições), sendo duas fontes minerais (inorgânica e orgânica) e três níveis de óleo de alecrim (0, 100 e 200 mg kg-1). Semanalmente os dejetos foram coletados, pesados e realizados os cálculos de produção de dejetos, coeficiente de resíduo (Cr) e as análises de sólidos totais (ST), sólidos voláteis (SV), pH, macro e microminerais. As fontes de minerais afetaram as características qualitativas dos dejetos. Os níveis de óleo de alecrim afetaram as características quantitativas e qualitativas do dejeto gerado. Concluiu-se que dietas contendo mineral orgânico resultam em dejetos com menor poder poluente por apresentar menores valores de ST, pH, N total e P total. O óleo de alecrim aumenta a produção de dejetos na MN e aumenta os valores de ST e SV nos dejetos das poedeiras causando maior impacto ambiental.

Utilization of recycled construction and demolition waste to improve the bearing capacity of loose sand: an integrated experimental and numerical study

ABSTRACT The present study examines the efficacy of the thickness of recycled construction and demolition waste (RCDW) layer (0.4D, 0.6D, 0.8D, 1D and 1.2D; D: diameter of footing) prepared at different relative densities (30%, 50% and 70%) overlaying on loose sand. Two sizes of RCDW, 5 mm named RCDW-I and 10.6 mm named RCDW-II, were used in this investigation. The plate load test and finite element analysis using ABAQUS were carried out on different combinations. Moreover, a large box direct shear test was conducted to determine the angle of internal friction (α) of RCDW-I and RCDW-II at relative densities (ID) of 30%, 50% and 70%. With the usage of RCDW layer over sand, the ultimate bearing capacity increases by 640% for RCDW-I and 597% for RCDW-II, and the corresponding decrement in the settlement was 36.86% and 33.54% (at ID = 70% and u = 1.2B), respectively. The conjoined analysis shows that RCDW-II performs better than RCDW-I at lower ID. Whereas the opposite trend is witnessed at higher ID. The experimental results were compared to the numerical model created in ABAQUS 3D. In addition, regression analysis was performed using SPSS software to build empirical expressions of the given results.

Seepage Model of Heterogeneous Municipal Solid Waste Landfill and Application under Process of Waste Accumulation

The distribution of leachate directly impacts the safety and stability of the landfill, so it is important to research the distribution of seepage characteristics and migration patterns of leachate. The study aims to investigate the impact of heterogeneous permeability distribution and clogging of the drainage layer on leachate transportation in landfills. To achieve this, a heterogeneous transient seepage model was developed. Results showed that when considering the heterogeneous permeability of the waste in the buried depth direction, the maximum perched water level was higher, which is not conducive to the safety and stability of the landfill. Taking Xi’an Jiangcungou Landfill as a research object, the maximum perched water level of each waste layer was higher compared to the homogeneous condition when considering the landfill process and heterogeneous permeability. The differential value ranged from 0.08 m to 1.88 m. Furthermore, the calculation results obtained from the heterogeneous seepage model were found to be in good agreement with both actual field data and referenced survey data, thus confirming the reliability of the model. These research findings not only offer technical support but also provide a solid theoretical foundation for leachate level control and safety and stability assessments.

The Content of Pollutants in the Melt Water of the Snow Polygon (Yuzhno-Sakhalinsk)

The results of monitoring the dynamics of the release of pollutants into the environment with meltwater from the snow landfill were presented. The concentrations of pollutants in water at the beginning and end of the active melting period were identified. The concentrations of pollutants were found to exceed background values for heavy metals. The concentrations of pollutants in meltwater at the beginning and end of the period of active melting were analyzed. At the end of the period, a decrease in the concentration of most pollutants was detected, with the exception of some of them, such as Fe, the concentration of which was 17 times higher, which is associated with the high iron content in the waste layer of the landfill. A significant increase in the concentration of pollutants was detected at the site of sedimentation of sludge in the swamp ditch.

Evaluation of acute phytotoxicity of raw leachate and landfill leachate using Sorghum bicolor seeds

Background: Leachate, a highly contaminated liquid, is produced by separating wastes and introducing moisture into the waste layers. Biological toxicity evaluation is a method that may be used to analyze the toxicity of leachate to organisms and plants. Sorghum bicolor was employed in this study to evaluate the acute toxicity of raw leachate and landfill leachate. Methods: Leachate was collected from different locations within the refuse that was collected and mixed in a sampling container. The physiochemical characteristics of the leachate were analyzed in both raw leachate and landfill leachate. Germination rate, root weight, and root length were measured 24, 48, and 72 hours after planting for leachate dilutions of 25%, 50%, 75%, and 100%, respectively. Results: Raw leachate had greater concentrations of metals (Fe, Zn, Cu, Mn, Cr, Cd, and Pb), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), nitrate, ammonia, and phosphate, as well as a more acidic pH (<6), as compared to landfill leachate. The results showed that landfill leachate had a lower potential for toxicity than raw leachate, with seed-germination rates of 0.1 and 0 in the presence of 75% landfill leachate after 48 and 72 hours, respectively, as opposed to 0.3 and 0.1 in the presence of raw leachate. Conclusion: The findings show that raw leachate can include higher concentrations of metals and organic compounds, which can be one of the causes of Sorghum seed phytotoxicity. Waste leachate management is one of the most important pillars of environmental protection, and it should be taken into consideration by the right authorities.

Optimizing Landfill Capacity: A Numerical Study of the Slope Inclination Variation Impact on Landfill Storage Capacity and Its influence on the Safety Factors under Different Models

As an attempt to enhance landfill capacity and extend its lifespan, this research explores the effect of slope inclination on landfill storage capacity and its implementation on the safety factors using numerical simulations. A geometric approach was used to determine the capacity change with inclination, and a new probabilistic calculation method, which accounts for the heterogeneity of waste layers, was employed to analyze the safety factor for different slope angles. Over 100 conducted calculations for each inclination were used to investigate the effect of slope variation on landfill safety. The results show that increasing inclination leads to a significant increase in landfill capacity. The safety factor results indicate that the conventional method, assuming homogenous waste, classifies 1:3 and 1:2 slopes as safe, while the new suggested method showed that a 2:3 inclination could be considered safe, especially since the calculation is not considering the safety-enhancing effect of daily cover layers. This study highlights the importance of considering the heterogeneity of waste layers in safety factor analysis, and the use of multi-layered nonhomogeneous calculation method, which provides more flexibility in design parameters. This research presents a significant step forward in constructing safe and cost-effective landfills. The use of a new probabilistic calculation method in designing landfills leads to more accurate and reliable results while maintaining safety standards. This research has important implications for the design and management of landfills and can be used as a guide for future studies in this field.

Effects of Metal Waste Strips on Strength Characteristics of Road Base Material

Metal manufacturing produces various types of byproducts and metal waste that have been growing exponentially. The increasing amounts of metal waste are usually disposed of in landfills, which causes soil and water pollution and increases the amount of gas emissions. On the other hand, in the field of pavement construction, the demand for natural materials is increasing rather rapidly. Many studies have suggested utilizing aggregate-like waste material in pavement construction, but there is little to no literature documenting the use of metal strips of different types. The aim of this study is to investigate utilizing the metal waste produced by the Intag Sohar company in layers of flexible pavement. Selected types of metal waste were utilized in the construction of the material used for base and subbase road layers. Three main parameters were studied: the number of layers, the distance between strips, and the direction of the strips. The effect of the metal waste on the pavement material is evaluated using the standard California Bearing Ratio test (CBR), which is the most important indication of the strength of the pavement material. Results show that the highest-quality mix consisted of four layers of metal waste with 1 cm spacing in one direction with CBR% values equal to 118.807%.

Distributed mathematical model for simulating temperature profile in landfill

Elevated Landfill temperatures have an undesirable effect on landfill cover, stability, slope and leachate migration pattern. Thus, to predict the temperature profile in the landfill a distributed numerical model using MacCormack finite difference method is developed. The developed model considers stratification of the upper and lower layers of the waste as new and old waste by assigning different values of heat generation for aerobic and anaerobic processes. Further, as the new layers of the waste get accumulated over the older layers, the density, moisture content and hydraulic conductivity of the underlying waste layers get modified. The mathematical model utilizes a predictor–corrector approach with a Dirichlet boundary at the surface and no flow condition at the bottom. The developed model is applied to the Gazipur site located in Delhi in India. A correlation coefficient of 0.8 and 0.73 is obtained between the simulated and observed temperatures in calibration and validation respectively. The result shows that the temperature at all the depths and in all the seasons was found to be higher than the atmospheric temperature. The maximum difference of 333 °C was observed in December, and the minimum difference of 22 °Cs was observed in June. The temperature rise is higher in the upper waste layers as it undergoes aerobic degradation. The locus of the maximum temperature gets modified with moisture movement. Since the developed model shows a good agreement with the field observation, it can be used to predict the temperature variation within the landfill under different climatic conditions.

Bisphenol A monitoring during anaerobic degradation of papers with thermochromic prints in soil

Pseudoestrogene bisphenol A (BPA) can be important ingredient of thermochromic inks, increasingly used materials in thermal printing paper, security printing, advertising, design and as temperature indicators in medicine and food industry. BPA mass fraction in thermochromic inks can be up to several percent. Hence, disposal of items with thermochromic prints pose a risk of environmental pollution. In this work BPA mass fraction was monitored during anaerobic degradation of papers with thermochromic prints in soil in both matrices: papers and soil. The degradation conditions simulated deeper layers of waste at a landfill site. Six types of papers with prints of thermochromic ink containing 2% of BPA were subjected to anaerobic degradation over up to 150 days. Initial mass fractions of BPA in papers decreased form (126–460) μg/g to (<QL – 45) μg/g after 150 days. BPA amounts were reduced 10 to 50 times depending on the paper type: least for synthetic paper and most for wood-free coated. For soil analysis new HPLC-UV method was developed and validated. The method was linear from 0.75 ng/g to 0.6 μg/g of BPA in soil with correlation coefficient of 0.9994. Method precision was 4.4%, accuracy 83% and detection limit 0.9 ng/g. Expectedly, amount of BPA in soil was increasing during the experiment. Mass fractions of BPA in soil were from not detected in earlier stage of degradation to (4.9–23.2) ng/g after 150 days. Final BPA amounts in soil were similar to those found in industrial, urban and agricultural soils worldwide. Hence, BPA from papers with thermochromic prints was notably decomposed, and contaminated soil had the capacity to absorb and decompose BPA even under anaerobic conditions. After 150 days of anaerobic degradation, only up to 1.86% of BPA contained in paper prints was found in soil, whilst, on average, 4% of initial BPA remained in paper.

Upcycling Chips‐Bags for Passive Daytime Cooling

AbstractPlastic pollution has caused numerous environmental issues in recent decades. As one of the most commonly used packaging materials, aluminum‐plastic laminates (APL) are particularly challenging for recycling purposes due to their sophisticated materials components. This work reveals a new strategy to upcycle such post‐consumer APL packaging waste, e.g., chips‐bags, for passive daytime cooling applications. This opens an attractive route to reuse APLs while at the same time reducing global energy consumption and carbon emissions. The mirror‐like appearance of the APLs possesses a strong solar reflection, up to 86%. By coating, this reflective layer of the APL waste with a high emissive polydimethylsiloxane layer, a simple but effective passive daytime cooling foil is constructed, which shows promising passive cooling performance theoretically and practically. More importantly, the passive cooling foil based on APL waste is flexible and can be applied to any target object, protecting it from harsh sunlight. The low‐cost APL waste‐based passive cooling foil proposed in this work will significantly contribute to both energy and environmental issues that humans face today.

Surface emission determination of selected trace gases from an active municipal solid waste dumpsite under the surface physicochemical heterogeneity.

Karadiyana municipal solid waste (MSW) dumpsite in Colombo, Sri Lanka, has been in operation for over 30years and was evaluated for its surface Volatile Organic Compounds (VOCs), Ammonia (NH3), and Hydrogen sulfide (H2S) emissions. Based on the surface conditions and waste characters, the dump surface was divided into eight cells, and multiple samplings were done using static flux chamber methods. The study observed that the average flux rates of VOCs, H2S, and NH3 were 137.2±243.8, 6.63±15.9, and 14.2±16.2mgm-2h-1 throughout the dump site. The highest average VOCs and H2S flux rates (828.6, 24.3mgm-2h-1) were reported from new organic waste with a considerable fraction (62.5, 35.6%) from the total emission (61.0, 3.1 Kg d-1). Leachate-flowing trenches produced the highest NH3 flux rate (36.0mgm-2h-1), while the highest emission fraction (47.5%) from the total (12.0 Kg d-1) was reported on old mixed waste with vegetation. The moisture content of the organic waste layers is positively correlated with these trace gas flux rates, and the NH3 flux rates depend on the pH of the surface. Results showed that the age of the waste determines the trace gas emission rate, and leachate provides an ideal pathway for landfill trace gas migration to the atmosphere. Gas collection and purification systems are essential for the initial waste dumping area and leachate treatment system. The arrangement of a proper drainage system on the dump would reduce trace gas emissions.

Microscopic synchrotron X-ray analysis of mercury waste in simulated landfill experiments

AbstractMercury enters into the environment or waste streams because it is present as an impurity in natural minerals. Mercury must be appropriately managed as an hazardous waste. In this study, a waste layer of artificial mercury sulfide mixed with incinerator ash and sewage sludge compost in a simulated landfill experiment for 5 years was analyzed using microscopic synchrotron X-ray to obtain basic knowledge of mercury behavior in a landfill. Mapping by synchrotron X-ray revealed the distribution of mercury-containing particles in the waste layer. In most cases, the movement of mercury sulfide was not considered significant even within a microscopic range; however, water flows could enhance the movement of mercury sulfide particles. When disposing of mercury sulfide, “concentrated placement” or solidification, rather than mixing with other wastes, was more effective at preventing mercury leaching in lysimeters. The chemical form of mercury sulfide in each lysimeter was confirmed by X-ray absorption fine structure (XAFS) analysis, which showed that most of the mercury was present as metacinnabar and had not undergone any changes, indicating that it was extremely stable. The microscopic synchrotron X-ray analysis proved very useful for studying the behavior of mercury waste in a simulated landfill experiment.