Leachate Containment Research Articles

Environmental safety performance dynamics and estimation of the deterioration of leachate containment elements: Implications for the lifespan of hazardous waste landfills

In the coming decades, the failure and expiration of over 100,000 landfills involving billions of tons of waste not only threaten global water security but also lead to a sudden increase in the global demand for solid waste disposal. Therefore, further research is needed on the ways in which landfill performance is degraded, their life expectancy, the factors that influence them and the ways in which they are influenced. A study estimated the performance degradation and expected lifespan of a modern hazardous waste landfill in China. The landfill experienced slow performance degradation in early years (0–12 years). But during mid-term (12–62 years) due to the rapid degradation of the liner material, the rate of leakage from the containment layer will increase by a factor of 4.8–27.1, leading to its earliest failure after about 38 years. This indicates the need for measures to prevent rapid performance degradation in the middle of the landfill's service life and to strengthen monitoring of performance indicators and environmental medium pollution in the later period (after 62 years) to respond to potential scrapping and pollutant leakage problems. Differences in construction quality and regional climate can cause differences in the lifespan of landfill facilities by up to 20 and 30 times, highlighting the importance of scenario-based failure and lifespan prediction for designing reasonable monitoring plans and preparing response measures to prevent potential groundwater pollution and to meet the sudden increase in demand for secondary waste disposal.

ANALYZING THE EXTENT OF LEACHATE FROM A MAJOR DUMPSITE WITHIN THE CRETACEOUS SEDIMENTS OF IKOM-MAMFE EMBAYMENT, SOUTHEAST NIGERIA

Groundwater resources in the region serve as a vital source of potable water for local communities and are essential for supporting various socio-economic activities. Unfortunately, the infiltration of leachate from dumpsite contributes to the dispersion of contaminants within the cretaceous sediments, posing a potential threat to groundwater quality. This study presents an exhaustive examination of leachate extent emanating from a prominent dumpsite situated within the Cretaceous sediments of the Ikom-Mamfe Embayment, Southeast Nigeria. Employing meticulous soil sampling methodologies and water collection from strategically positioned boreholes near the Ikom dumpsite, advanced techniques such as Electrical Resistivity Tomography (ERT) and Vertical Electric Sounding (VES) were utilized to scrutinize the infiltration of leachate within the site. Laboratory analyses were conducted to evaluate the concentrations of heavy metals, including Lead, Mercury, Arsenic, Nickel, Chromium, and Cadmium, in both soil and borehole water samples. The findings unveiled alarming levels of Lead and Cadmium concentrations in the soil, exceeding established regulatory thresholds, with recorded values ranging from 552.34 to 556.93 mg/kg and 11.88 to 7.46 mg/kg, respectively. Similarly, borehole water analyses in the vicinity of the Ikom dumpsite revealed elevated concentrations of Arsenic, Lead, Cadmium, and Nickel, surpassing WHO limits in specific boreholes (BH2 and BH3), indicative of potential soil porosity issues and unfavorable geological conditions prevalent in the study area. Notably, the use of ERT delineated an inverse resistivity of 5.99 Ωm at a depth of 9.26 m, pinpointing the leachate-infiltrated cretaceous sediments zone, extending laterally from 10m to 40m along the profile. The observed infiltration of leachate at 9.26 m depth underscores its penetration into the sandstone, shale, and dark gray shale strata within the dumpsite. Furthermore, the quantified thickness layer ranging from 1.41 to 4.37 affirmed leachate infiltration within the sandstone, shale, and dark gray shale strata, with implications for its movement and containment dynamics. This study underscores the critical role of layer thickness in influencing the migration and containment of leachate, with thicker layers potentially acting as barriers to its movement, while thinner layers may facilitate more rapid migration. Additionally, the assessment of aquifer protective capacity, denoted by ratings below (<0.1), underscores the poor protective capacity of the aquifer system in the study area. In light of these findings, strategic management, remediation, and vigilant monitoring measures are advocated to mitigate contamination risks and safeguard water quality.

Experimental Investigation of Red Soil Blended With Bentonite and Lime as a Landfill Liner

To control the migration of contaminants generated from the leachate, the liners are used in landfills. Compacted clay liners are widely used as liner materials due to the low value of hydraulic conductivity and large attenuation capacity. In the present work, an experimental study on red soil which is locally available is amended with bentonite use as a liner material for efficient leachate containment in landfills. The primary objective of this work is to determine the geotechnical properties of red soil blended with bentonite as a material for liners. The clay liners performance primarily depends on hydraulic conductivity. The hydraulic conductivity of the red soil is higher than the recommended limit (i.e.>10-7cm/s). Commercially available bentonite was blended with red soil to decrease the hydraulic conductivity. The permeability tests and falling head tests were conducted on 5%, 10%, 15%, and 20% bentonite by weight blended with red soil to evaluate hydraulic conductivity. From the experimental studies, it is clear that the red soil blended with 15% bentonite has a hydraulic conductivity value less than the requirements of landfill clay liner(i.e.<10-7cm/s). However, the Compressive Strength (CS) of blended red soil with 15% bentonite was less than 200 kPa, which is less than the minimum CS required for liner material. Lime was added to enhance the CS of the soil mixture and further studies were carried out. Swelling behavior is the major problem that is to be addressed during and after the construction of landfills. This study also presents the swelling behavior of red soil blended with bentonite and other additives.

Straightforward preparation of Ca-bentonite/polymer nanocomposite by confining salt-resistant copolymers into montmorillonite interlayers

Calcium bentonites (CaB), rich in European and Asian countries, are potential barrier materials for landfill leachate containment. However, CaB has to be converted into sodium bentonite (NaB) by Na-activation so as to facilitate intercalation modification. In this study, salt-resistant poly(acrylic acid-N, N-diethyl acrylamide) [P(AA-DEA)] was designed to intercalate and graft CaB by in situ polymerization without prior Na-activation. By this design, acrylic acid monomers were first adsorbed into interlayers of Ca-montmorillonite (Ca-MT) through the electrostatic complexation with Ca2+, dislodging Ca2+ from montmorillonite surfaces. Then, ammonium ions of N, N-diethyl acrylamide were adsorbed into Ca-MT interlayers. Swelling index of the obtained CaB/P(AA-DEA) nanocomposite in aggressive coal combustion product (CCP) leachate is 15.8 mL/2g, which is as high as 3.4 times that of CaB. CaB/P(AA-DEA)-based geosynthetic clay liners (GCLs) exhibit very low hydraulic conductivity (1.6✕10−12 m/s) to CCP leachate, which is as low as 3.3% that of the U.S. standard requirement and ∼4 orders of magnitude lower than that of CaB-based GCL. Polymer elution of CaB/P(AA-DEA)-8% in CCP leachate is as low as 1.9% that of the dry mixed samples.

Impacts of Addition of Palm Kernel Shells Content on Mechanical Properties of Compacted Shale Used as an Alternative Landfill Liners

The design of landfill liners of waste disposal to reduce migration of leachate containment, low swelling, and shrinkage and ensure sufficient shear strength to resist bearing capacity and instability of the landfill has been a major challenging task to landfill engineers. Over the last decade, there has been an increase in research on the stability of substitute materials as liners that are environmentally friendly, cost-effective, and socially beneficial due to the growing cost of traditional landfill liners. In this regard, geotechnical tests were conducted on shale samples treated with 0–12% (increment of 2%) of palm kernel shell ash (PKSA) and pulverized palm kernel shell (PPKS) to evaluate their suitability as alternative landfill liners using West African Standard (WAS) and Modified AASHTO Standard (MAS) for compactive energy. The shale has more percentage of finer fractions, thus classified as poorly graded soil (A-7-5). The Atterberg limit tests show that liquid and plastic limits decrease with an increase in plasticity index as the percentage of addition of PKSA and PPKS content increases. The results also established that the maximum dry density (MDD), volumetric shrinkage strain (VSS), and hydraulic conductivity significantly decrease, while the optimum moisture content (OMC) increases as the content of PKSA and PPKS increases at both compactive efforts. The maximum strengths of 380.30 and 448.70 kPa were obtained at 4% of both stabilizers. From the results, it can therefore be concluded that the treated compacted shale meets the condition of the suitability of landfill liners. Furthermore, with the use of industrial and agricultural wastes such as palm kernel shells as replacement materials with natural soils used as liners, significant social, economic, and environmental impact of landfills and reduction in wastes can be achieved. The research results can provide a reference for similar conditions of landfill liners worldwide.

Evaluation of the Hydraulic Conductivity of Compacted Laterite-Metakaolin Mixtures for Solid Waste Leachate Containment

This paper presents the results of a study conducted to investigate the benefits of using metakaolin (MK) with laterite as liner material for containment of municipal solid waste (MSW). Laboratory tests were conducted on laterite specimens treated with MK at concentrations of 0 - 20 % by weight of the soil and compacted using four types of compaction energies. Hydraulic conductivity was determined based on permeation of the compacted laterite - MK mixtures with deionized water (DW) and municipal solid waste leachate (MSWL), respectively. Deionized water was the reference permeant fluid. The results showed that hydraulic conductivity generally decreased with increase in the percentage addition of MK to the soil. From an economic and sustainability point of view, it has been found from the results that 5 % MK can be added to soil and compacted at moulding water content of 14.1 % using the West African Standard (WAS) compaction energy to achieve the regulatory hydraulic conductivity of less than or equal to 1 x 10-9 m/s for compacted soil liner. The natural logarithm of the hydraulic conductivity experimental results were computed and used to develop regression equations for estimating hydraulic conductivity given MK contents and compaction energies. The results of the two-way analysis of variance (ANOVA) test carried out at 5 % level of significance showed that calculated F-statistics are statistically significant and the measured values of hydraulic conductivity compare well with the predicted values. The developed models can therefore be used to give good estimates of hydraulic conductivity of soils having similar properties with the laterite investigated in this study. Therefore, the developed models can be used to give good estimates of hydraulic conductivity of soils having similar properties with the laterite investigated in this study. Keywords ­_ Deionized water, Hydraulic conductivity, Leachate, Metakaolin, Municipal solid waste.

Delineation of leachate pathways using electrical methods: case history on a waste plaster landfill in South Korea

ABSTRACTA waste plaster landfill site, established as a high-density polyethylene (HDPE) sheet pile surrounded by a slurry wall to isolate possible contaminants within the landfill, was investigated using electric survey techniques. A sheet pile is an effective barrier wall for contaminated leachate containment, unless there are damaged zones within the pile. However, the perfect insulating properties of the pile make it difficult to apply the electrical resistivity method to measure the containment ability of the pile. To locate damaged zones in the sheet pile, which can act as pathways for the contaminated leachate, a potential difference (PD) profiling technique was applied. Through three-dimensional (3D) modelling, PD profiling demonstrated efficacy in locating damaged zones in the sheet pile. Moreover, a 3D survey was conducted to delineate the leakage pathways through the sheet pile, as well as the leachate distribution throughout the landfill. Before the 3D inversion of measured resistivity data, erroneous data caused by the sheet pile were rejected to minimise distortion of the inversion results. 3D inversion showed the sheet pile to be highly resistive overall, especially at shallow depths; however, further inspection via PD profiling identified several areas of damage in the pile. These damaged zones from PD profiling coincided well with the low resistivity zones present near the surface in the 3D inverted image. Furthermore, major leaks were found below the burial depth of the sheet pile. Thus, it was demonstrated the PD profiling and 3D resistivity survey can locate damaged zones in the sheet pile and delineate leakage pathways over the landfill site.

Investigation of Biobarrier for Leachate Containment through Batch and Continuous Flow Studies

AbstractThe effectiveness of biobarrier for leachate containment was investigated through continuous flow column studies. Landfill leachate collected from Ariyamangalam open dumping site was used as the source for microorganism isolation. Isolated organisms were enriched in the presence of lead to selectively obtain lead-tolerant microorganisms. The biochemical analysis results confirmed that the isolated strain is gram positive and rod shaped, Bacillus insolitus. Synthetic leachate was inoculated with different cultures of bacteria and was aerated to an initial dissolved oxygen level of 7.8 mg/L. In the batch reactor, chemical oxygen demand (COD) and lead removal was higher for lead-enriched cultures (62 and 28%) when compared with the nonenriched cultures (57 and 13%). The initial hydraulic conductivity of 1.99×10−2 cm/s was reduced to 1.1×10−3 cm/s at the end of 36 days of continuous study of the microbial sand column (MC), whereas negligible reduction was observed in blank column without microbes (...

English

Modern landfill typically contain several geosynthetic and natural components integrated into a system whose primary function is the containment of waste and leachate. The physical interactions between these individual components must be carefully evaluated to ensure that the stability and performance of the liner system is provided in the long term. Geomembrane HDPE are gaining increasing acceptance in landfill liner systems, yet their interactions with other components in the system are often not well understood. This paper indentifies some of these interactions and suggests methods for landfill structure design.. This paper presents a design of landfill structure at PT. Toba Pulp Lestari Tbk., Medan, Nord Sumatra. The landfill dimension is 10000 m 2 and 15 m depth.

Potential use of calcareous mudstones in low hydraulic conductivity earthen barriers for environmental applications

Earthen layers play a significant role in isolating contaminants in the subsurface, controlling the migration of contaminant plumes, and as landfill liners and covers. The physical, chemical and mineralogical properties of three calcareous mudstones from the Jagüel and Roca formations in North Patagonia, Argentina, are evaluated to determine their potential for the construction of liners. These mudstones were deposited in a marine environment in the Upper Cretaceous–Paleocene. The tested specimens mainly comprise silt and clay-sized particles, and their mineralogy is dominated by a smectite/illite mixed layer (70–90% Sm) and calcite in smaller proportion. Powdered mudstone samples have little viscosity and swelling potential when suspended in water. The hydraulic conductivity of compacted mudstones and sand–mudstone mixtures is very low (around 1–3×10−10 m/s) and in good agreement with the expected hydraulic behaviour of compacted earthen layers. This behaviour can be attributed to the large amount of fine particles, high specific surface and the close packing of particles as confirmed by scanning electron microscope analysis. The tested materials also show a high cation exchange capacity (50–70 cmol/kg), indicating a high contaminant retardation capability. The calcareous mudstones show satisfactory mineralogical and chemical properties as well as an adequate hydraulic behaviour, demonstrating the potential use of these materials for the construction of compacted liners for the containment of leachate or as covers in landfills. These findings confirm the potential usage of marine calcareous mudstones as a low-cost geomaterial in environmental engineering projects.

Geonets and Geotextiles as Leachate Containment Materials in Landfills: System Dynamics Modeling Perspective

Geonets and Geotextiles as Leachate Containment Materials in Landfills: System Dynamics Modeling Perspective

Improvement of attenuation functions of a clayey sandstone for landfill leachate containment by bentonite addition

Enhanced sand–clay mixtures have been prepared by using a sandstone arkosic material and have been evaluated for consideration as landfill liners. A lab-scale test was carried out under controlled conditions with different amended natural sandstones whereby leachate was passed through the compacted mixtures. The compacted samples consisted of siliceous sand (quartz–feldspar sand separated from the arkose sandstone) and clay (purified clay from arkose sandstone and two commercial bentonites) materials that were mixed in different proportions. The separation of mineral materials from a common and abundant natural source, for soil protection purposes, is proposed as an economic and environmentally efficient practice. The liner qualities were compared for their mineralogical, physicochemical and major ions transport and adsorption properties. Although all samples fulfilled hydraulic conductivity requirements, the addition of bentonite to arkose sandstone was determined to be an effective strategy to decrease the permeability of the soil and to improve the pollutants retention. The clay materials from arkose sandstone also contributed to pollutant retention by a significant improvement of the cation exchange capacity of the bulk material. However, the mixtures prepared with clay materials from the arkose, exhibited a slight increase of hydraulic conductivity. This effect has to be further evaluated.

사용종료매립지 정비를 위한 흙-시멘트 연직차수벽의 차수성능 평가

This study was conducted to evaluate the performance of soil-cement walls (SCWs) to control leachate from a leaking landfill site. Tracer tests revealed that the SCW was effective to control groundwater seepage. Approximately two-months of curing period appeared to be sufficient to ensure thorough containment of landfill leachate, although a three-week period was not enough. The water quality of the monitoring wells after construction of the SCWs met the groundwater quality standard of the korean Waste Management Act, except for bacteria and coliform groups. Also an analysis of a spring water around the landfill showed that the concentrations of ammonia, inorganic nitrogen and soluble manganese which had been common contaminants in the spring water decreased dramatically after constructing the walls. Therefore, the results suggested that a SCW can be an attractive method to control leachate from a leaking landfill site.

Selection of Cementitious Mixes as a Barrier for Landfill Leachate Containment

Cementitious materials have traditionally not been economically viable for most landfill containment systems. Conventional liners have been made with clay and high-density polyethylene membranes, supporting packed aggregate layers. This paper describes an alternative technology in which low-cost concrete liners may be constructed, making use of materials, which are considered to be wastes by their primary producers. Many materials that have the potential for use either as binder or as aggregate materials for concrete currently form part of the United Kingdom landfill inventory. Although unattractive for use as structural concrete, they offer considerable utility for landfill liner applications. Recent increases in disposal costs including the introduction of the landfill tax have, however, made low cost low strength mixes a financially attractive option as a barrier for landfill leachate containment. In this paper the required properties of cementitious mixes for this purpose are discussed. The results of an extensive investigation into potential mixes using various mineral wastes are presented and the measured properties are compared with those, which are required. All of the mixes, which have been investigated, contain large amounts of secondary materials. If these materials were treated as wastes their disposal costs would be high, so the mixes may be designated “negative cost mixes.” The results indicate that some of these mixes are well suited to this application.

Observations of the impacts of some landfill leachates with clays

Compacted day liners are common, major, components of landfill leachate (fluid) containment systems. This is sensible, but knowledge and understanding of the long‐term performance and behaviour of clay mineral/ landfill leachate systems remain very limited. The authors studied the reactions of clay soil with leachate simulants related to three different climates and waste cultures. The clay came from a Tertiary sequence near Melbourne, Australia, a type in common use locally for landfill engineering. X‐ray diffraction was used to observe mineralogical change in 3 mm clay plugs caused by reactions with the leachate simulants. Changes in hydraulic conductivity were also measured. The results show both that the different leachates have distinct effects on the clay minerals, and that the leachate/clay reactions have direct, measurable and distinct impacts on hydraulic conductivity. The laboratory studies were completed at the University of Melbourne. The X‐ray diffraction work was completed at The Natural History Museum in London. The experimental results are discussed here and indications given of some potential implications

An Expert System for Landfill Leachate Management

A prototype expert system, called the Leachate Management Advisor (LMA), has been developed to assist in the conceptual design of leachate management facilities in a sanitary landfill. The expert system aims to establish the expected leachate production and its polluting potential, recommend a policy for leachate containment, investigate whether lining, leachate collection or treatment is/are necessary, and, if so, perform conceptual design for the required components. An expert system shell, Kappa-PC, was selected as the development tool for the LMA prototype because of its object-oriented approach, which combines the two main knowledge representation techniques for expert systems, i.e. production rules and objects. An object-oriented model of the domain was successfully developed where the rule-based reasonings and other decision processes operate on or across objects representing real-world entities of the domain. Expertise in the knowledge base was acquired from 12 textual sources and 10 landfill practitioners in Malaysia. The overall performance of the LMA was evaluated to be satisfactory based on a case study of an actual landfill site.

In Situ Anaerobic Treatment of Leachate in Landfill Bioreactors

Landfills often serve as ultimate receptors for residential, commercial and industrial wastes. Both hazardous and nonhazardous wastes may be codisposed, but with potential threats to public health and the environment if not properly managed. Therefore, an understanding of the fundamental attenuating mechanisms determining mobilization and potential transport and fate of codisposed waste constituents is needed to direct the selection of appropriate landfill operational and management strategies. By focusing on changes in leachate and gas characteristics during codisposed loadings of organic and inorganic hazardous wastes, the potential treatment capacity of bioreactor landfills with leachate containment and in situ recirculation could be demonstrated.

Clay membrane made of natural high plasticity clay: leachate migration due to advection and diffusion

Leachate containment in Denmark has throughout the years been regulated by the DIF Recommendation for Sanitary Landfill Liners ( DS/R 466). It states that natural clay deposits may be used as membrane material provided the membrane and drainage system contains at least 95% of all leachate created throughout the lifetime of the landfill. Presently, the recommendation is under revision partly because this clause was considered to be insufficient for securing the drinking water quality in underlying aquifers — a necessary containment of at least 99% is foreseen. The revision should consequently take into account advective ion transport as well as diffusion. Clay prospecting for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island of Lolland. The natural clay contains 60–75% smectite, dominantly as a sodium-type. The clay material has been evaluated using the standardized methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15–0.3 m thick clay membrane have been tested successfully. At a natural water content of w=40–45% it is possible to establish a homogeneous membrane with hydraulic conductivity k<5×10 −12 m s −1 giving an extremely low transport by advection. The hydraulic conductivity measured in oedometer tests used for establishing swell and deformation properties were shown to be very dependent on the stress level. It varies from k=10 −11 to 2×10 −13 m s −1 at vertical stresses from 5 to 4800 kPa and is clearly related to a reduced effective porosity diminishing with stress. Preliminary diffusion tests indicate a similar influence on the effective diffusion coefficient being much lower than anticipated using the total porosity. These properties are of major importance to the future use of clay membranes for the containment of hazardous waste. In order to explain these properties microstructural investigations were initiated to establish the boundary conditions for the evaluation of relevant transport processes. Consequently, this clay material may be used as raw material to be compacted for membrane purposes in a natural wet condition using high compaction effort comparable to the modified Proctor energy. It fulfils the requirements that are presently proposed in the new Danish Recommendation for Landfills and a number of other applications that are foreseen for clay embedment of hazardous waste.

Decision Analysis for Leachate Control at a Fractured Rock Landfill

AbstractThe municipal landfill at the Complexe Environnemental de Saint‐Michel (CESM) in Montreal, which is the third largest in North America, is located in a former quarry in fractured limestone. Impressive measures are taken to monitor and control biogas and leachate generated at the site. Leachate containment is presently performed with a pumping well completed within the waste. The efficiency of the well in controlling off‐site leachate migration is questioned because field observations strongly suggest that the nearby former Francon quarry is diverting local ground water flow. To address this issue, four additional hydraulic control options are considered: (1) increased pumping at the existing waste well; (2) new pumping wells in the rock on the eastern limit of the site; (3) new injection wells in the rock on the eastern limit; and (4) combination of new injection wells at the same location and new water supply wells upgradient of the landfill. We evaluated the four hydraulic control options at the CESM using two coupled models: (1) a decision model based on an objective function weighting the risk, costs, and benefits of each option translated into dollar units; and (2) a numerical ground water flow model to represent the effect of operational conditions and ascertain success. Decision analysis offers a quantitative unbiased tool to evaluate the potential and relative cost of each option, but qualitative considerations and judgment still must be used for a complete evaluation. Our analysis confirms that scenario 4, which was the intuitively favored option, represents the best containment strategy.

In situ anaerobic treatment of leachate in landfill bioreactors

Landfills often serve as ultimate receptors for residential, commercial and industrial wastes. Both hazardous and nonhazardous wastes may be codisposed, but with potential threats to public health and the environment if not properly managed. Therefore, an understanding of the fundamental attenuating mechanisms determining mobilization and potential transport and fate of codisposed waste constituents is needed to direct the selection of appropriate landfill operational and management strategies. By focusing on changes in leachate and gas characteristics during codisposed loadings of organic and inorganic hazardous wastes, the potential treatment capacity of bioreactor landfills with leachate containment and in situ recirculation could be demonstrated.