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Chakraborty R.,Ramakrishna Mission Shilpapitha | Ghosh A.,Indian Institute of Science | Ghosh S.,Jadavpur University | Mukherjee S.,Jadavpur University
Environmental Earth Sciences | Year: 2015

Hexavalent chromium (Cr6+) is released in the lithospheric environment through leachate pollution in chrome tanning industries. Transportation of Cr6+ containing plume through soil needs to be assessed by estimation of some mechanistic parameters such as diffusion coefficient (D), distribution coefficient (Kd) and retardation factor (R). An investigation was undertaken with three soil samples, S1, S2 and B, to examine their potential use as liner material for controlling Cr6+ pollution in soil environment. Batch adsorption kinetic test was carried out to estimate the Kd and R values of soil samples S1 and S2. A numerical solution technique was adopted for prediction of such transport parameters in simulated field condition using the finite difference method (FDM). The efficacy of the present numerical solution technique (FDM) is compared with subsequent column experiment data with Soil-B along with the analytical solution. It was observed that the experimental value of “D = 3.04 × 10−8 m2/s for Soil- B” by using the applied technique closely fitted to that value evaluated by the analytical method (r2 = 0.98). The values of ‘Kd’ for Soils S1 and S2 were found to be 0.008 and 0.021 mL/g, respectively, using batch adsorption. The values of ‘R’ of the soil samples S1 and S2 were obtained as 1.037 and 1.053, respectively. All the above results were obtained in correspondence to the initial hexavalent chromium concentration level of 7.5 mg/L in the simulated leachate sample. © 2015, Springer-Verlag Berlin Heidelberg.

Mukherjee S.,Ramakrishna Mission Shilpapitha | Mukherjee S.,National Institute of Technical Teachers Training and Research | Bhattacharya A.K.,Tellabs India Private Ltd | Mandal S.N.,National Institute of Technical Teachers Training and Research
International Journal of Sustainable Development and Planning | Year: 2014

Coagulation and fl occulation is one of the most effective, economic and convenient method for raw water clarifi cation. In recent times, different hydrolysing coagulants, particularly aluminium-based ones are in wide use. In the present study, different aluminium-based salts, polymer and coagulant aid were used to observe their effectiveness as well as side effects, if any. Turbidity was the prime criterion for clarifi cation of the raw water; however, the potentially hazardous residual aluminium was also given due importance. Poly-aluminium chloride (PACl) enhanced the performance of the potash alum when used in tandem, whereas bentonite powder used as coagulant aid proved ineffective in improving the performance of the potash alum with respect to the removal of the turbidity. PACl when used alone or in tandem with potash alum showed character signifi cantly different from aluminium-based salts only, with respect to the criterion of residual aluminium. © 2014 WIT Press.

Chakraborty R.,Ramakrishna Mission Shilpapitha | Ghosh A.,Bengal Engineering and Science University
International Journal of Geomechanics | Year: 2013

Finite-difference method (FDM) is applied herein to solve the three-dimensional (3D) contaminant transport model to predict pollutant migration through clay liner or clay deposit in waste landfill. The seven pollutant species typically found in municipal and industrial wastes are considered in this study. Physical processes such as advection, dispersion, diffusion, geochemical reactions, and first-order decay are considered in the governing equation. The computer program CONTAMINATE-3D was developed to solve the 3D analysis of the contaminant migration model. A comparative study between one-dimensional and 3D analysis is presented in this paper based on the proposed methodology considering unidirectional flow and dispersion in three directions. Based on the present 3D analysis, design charts for liners and concentration profiles of contaminant species passing through liner media were developed to facilitate the designers' work. Contaminant plumes were also developed within the aquifer considering unidirectional and uniform groundwater velocity to illustrate the effect of the vertical-plane patch source of constant concentration on the neighboring areas of the landfill site using the proposed solution technique of 3D contaminant transport model. © 2013 American Society of Civil Engineers.

Chakraborty R.,Ramakrishna Mission Shilpapitha | Ghosh A.,Bengal Engineering and Science University
Journal of Hazardous, Toxic, and Radioactive Waste | Year: 2012

Finite-difference method (FDM) has been adapted herein to solve a one-dimensional (1D) contaminant transport model to predict contaminant migration through soil in waste landfill underlying an aquifer. Providing an effective engineered barrier, which will separate the waste from groundwater, can minimize the potential contamination in the groundwater system. In this paper, a solution technique has been developed using FDM for the analysis of 1D contaminant transport in a layer of finite thickness. The present study considers the effects of advection, dispersion/diffusion, geochemical reactions, and decay in a single model with a finite quantity of pollutant in the landfill and transport of contaminants toward groundwater beneath the clay deposit/liner. The computer program CONTAMINATE-1D-FM has been developed using the proposed solution technique to analyze the contaminant migration. The short-term and long-term effects of different factors influencing groundwater contamination have been presented in this paper. The values of the relevant parameters used by previous investigators have been adapted in the solution technique presented herein for prediction of contaminant migration. The effects of Péclet number and Courant number criteria have been considered to select appropriate time step and spatial size of the finite-difference grid to avoid oscillation and numerical dispersion. The proposed solution technique for contaminant transport with finite mass has been validated with a published analytical solution. The design of clay liner and the impact of important parameters on a groundwater system have been illustrated to facilitate field engineers.DOI: 10.1061/(ASCE)HZ.2153-5515.0000125. © 2012 American Society of Civil Engineers.

Chakraborty R.,Ramakrishna Mission Shilpapitha | Ghosh A.,Bengal Engineering and Science University
14th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering | Year: 2011

Implementation of effective techniques and procedures for treatment of contaminated sites to remove or minimize the concentration of pollutants constitutes the fundamental aim of remediation and pollution mitigation programmes. The techniques of removal of the offending pollutants are selected based on the physico-chemical and biological considerations. Finite difference method (FDM) has been adapted herein to solve and study the decontamination of a polluted stream using fresh water and bioremediation of petroleum contaminated soil using composting applying 1-D model. The efficacy of the model has been studied identifying the significant processes of contaminant migration, such as advection, diffusion-dispersion or decay or combination of these. The treatability time for removal of sodium ion, chloride ion and dichloromethane (DCM) from a deposited site by soil washing with clean water has been presented in this paper and helps the field engineers to take decision for selecting appropriate method of remediation. The computer program, REMEDIATE has been developed to solve the model.

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