Modelling contaminant transport in fly ash-bentonite composite landfill liner: mechanism of different types of ions (original) (raw)
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2022
Solid waste disposal management in the small/large cities of India is a major problem. The ancient method for disposing of solid waste was landfill. disposing of solid waste as landfill is important as it protects ground water contamination. A model material having low hydraulic conductivity may be used as filler material for disposing off the solid waste. It may also work as a barrier for hazardous waste and used as buffer/backfill materials. To overcome this problem the model material should have the low hydraulic conductivity to avoid percolation of leachate in ground water reserve. In present research, sand was procured from the bank of BENI River from Pantnagar, district Udham Singh Nagar, (Uttarakhand). Sodium bentonite was mixed with sand at varying proportions to make the model material. Physical properties were determined of the sand and sodium bentonite. Determination of Optimum moisture content (OMC), Maximum Dry Density (MDD), shear strength and hydraulic conductivity pr...
Landfills are the man-made places on land, where the wastes collected are dumped. In today's world landfills are a serious environmental pollution factor because of the emission of toxic gases and groundwater contamination. Major component of a landfill is its liner and to avoid such environmental health hazards, liner material should possess certain standard properties. Hence in this study, an attempt has been made to consider two kinds of mixes, namely, the clay-bentonite mix and the bentonite-quarry dust mix. The properties such as permeability and compressive strength of the mixes were determined.
Compacted sandy soils with addition of bentonite have been used in a variety of geotechnical structures as engineered barriers, such as in landfill liners and hydraulic containment structures. In this study, Igbokoda sand was mixed with bentonite at varying percentages of 0%, 2%, 4%, 6%, 8% and 10% by weight of sand. Strength tests, which include compaction test, California Bearing Ratio (CBR) test and direct shear test, were performed on various sand-bentonite mixtures using standard methods. Hydraulic conductivity tests were also performed on various sand-bentonite mixtures in order to determine their suitability as landfill liner. Results from the tests showed that 8% of bentonite with sand mixture had a hydraulic conductivity below 1×10-7 cm/s, a cohesion value of 250 kN/m 3 and a reasonable strength (CBR) value of 54.07% using the West Africa standard compactive method, hence being the safest of the selected varying percentages for the design of a landfill liner.
Landfill liners are used for the efficient containment of waste materials generated from different sources. In the absence of impermeable natural soils, compacted mixtures of expansive soil and sand have found wide applications as landfill liners. It is to be noted that, in case, these materials are not locally available, the cost of the project increases manifold due to its import from elsewhere. Also, sand has become an expensive construction material due to its limited availability. With this in view, the present study attempts to explore a waste material such as fly ash as a substitute for sand. The major objective of this study is to maximize the use of fly ash for the said application. Different criteria for evaluating the suitability of material for landfill liner have been proposed in this study. However, further investigations are required with different source of fly ash and alternative material to generalize the findings.
2014
This thesis presents the findings of laboratory work on behavior of landfill liner using crushed siltstone and kaolinite. The selection of landfill liner are based on compatibility with the soil environment, resistance of load from waste, and also groundwater levels. Inspired by using waste material as engineering purpose, therefore this study is to determine the physical properties of composite kaolinite clay-crushed siltstone liner, to predict the effect of composite on hydraulic conductivity and engineering characteristic of composite kaolinite clay-crushed siltstone liner and also to analyze the settlement result by using Plaxis Modelling.There is a paucity of the previous research, where the study on the liner material is lacking. Therefore, in the present study, an alternative liner made of composite material is studied and developed. The waste material that had been used in this studied was crushed siltstone which then sandwiched with kaolinite layers and vice versa. The crus...
Environmental and Sustainability Indicators, 2023
Liners are provided under engineering landfill sites to block the downflow of leachates and their noxious components to minimize pollution in the underlying aquifers or neighboring water bodies. Compacted clays are widely employed as suitable materials for constructing landfill liners because of their low hydraulic conductivity, balanced swelling potentials, and appropriate compressive strength. However, the quality has to be improved if the locally available soil does not meet the minimum standards for constructing liner materials. Including bentonite dosage with local soil can show better stability and strengthened cohesion bonds between molecules. This paper aims at a recent study on specific geotechnical properties of bentonite amended local Khulna clay soil intended to be used as a liner material. Bentonite in varying proportions (e.g., 5%, 10%, 15%, and 20%) was mixed with local soil, and specific tests (e.g., compaction tests, consistency tests, hydraulic conductivity tests, free swell tests, unconfined compressive strength tests, and pH tests) were conducted on the mixtures. Results indicated that the optimum moisture content (14.03%-19.30%), liquid (35.39%-53.98%), plastic (22.20%-35.23%), plasticity index (13.19%-18.75%), pH (7.23-7.43), swell index (3.13%-24.2%) and unconfined compressive strength (156.21 kPa-244.46 kPa) increased while bentonite was in conjuncture with the soil. In contrast, maximum dry density (17.80 kN/m 3 to 16.80 kN/m 3) and hydraulic conductivity (2.39 × 10 − 7 cm/s to 0.09 × 10 − 7 cm/s) decreased. Also, at 10% bentonite content, the mixture matched the acceptable standards for liner construction (hydraulic conductivity 0.29 × 10 − 7 cm/s <10 − 7 cm/s, and unconfined compressive strength = 210 kPa > 200 kPa).The study identified that adding bentonite to local soil can improve its geotechnical properties, making it a suitable material for landfill liners with increased strength and decreased hydraulic conductivity.