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  1. Article: Influence of dynamic coupled hydro-bio-mechanical processes on response of municipal solid waste and liner system in bioreactor landfills

    Reddy, Krishna R / Girish Kumar / Rajiv K. Giri

    Waste management. 2017 May, v. 63

    2017  

    Abstract: A two-dimensional (2-D) mathematical model is presented to predict the response of municipal solid waste (MSW) of conventional as well as bioreactor landfills undergoing coupled hydro-bio-mechanical processes. The newly developed and validated 2-D ... ...

    Abstract A two-dimensional (2-D) mathematical model is presented to predict the response of municipal solid waste (MSW) of conventional as well as bioreactor landfills undergoing coupled hydro-bio-mechanical processes. The newly developed and validated 2-D coupled mathematical modeling framework combines and simultaneously solves a two-phase flow model based on the unsaturated Richard’s equation, a plain-strain formulation of Mohr-Coulomb mechanical model and first-order decay kinetics biodegradation model. The performance of both conventional and bioreactor landfill was investigated holistically, by evaluating the mechanical settlement, extent of waste degradation with subsequent changes in geotechnical properties, landfill slope stability, and in-plane shear behavior (shear stress-displacement) of composite liner system and final cover system. It is concluded that for the given specific conditions considered, bioreactor landfill attained an overall stabilization after a continuous leachate injection of 16years, whereas the stabilization was observed after around 50years of post-closure in conventional landfills, with a total vertical strain of 36% and 37% for bioreactor and conventional landfills, respectively. The significant changes in landfill settlement, the extent of MSW degradation, MSW geotechnical properties, along with their influence on the in-plane shear response of composite liner and final cover system, between the conventional and bioreactor landfills, observed using the mathematical model proposed in this study, corroborates the importance of considering coupled hydro-bio-mechanical processes while designing and predicting the performance of engineered bioreactor landfills. The study underscores the importance of considering the effect of coupled processes while examining the stability and integrity of the liner and cover systems, which form the integral components of a landfill. Moreover, the spatial and temporal variations in the landfill settlement, the stability of landfill slope under pressurized leachate injection conditions and the rapid changes in the MSW properties with degradation emphasizes the complexity of the bioreactor landfill system and the need for understanding the interrelated processes to design and operate stable and effective bioreactor landfills. A detailed discussion on the results obtained from the numerical simulations along with limitations and key challenges in this study are also presented.
    Keywords biodegradation ; bioreactors ; equations ; landfills ; mathematical models ; municipal solid waste ; prediction ; temporal variation
    Language English
    Dates of publication 2017-05
    Size p. 143-160.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2001471-5
    ISSN 1879-2456 ; 0956-053X
    ISSN (online) 1879-2456
    ISSN 0956-053X
    DOI 10.1016/j.wasman.2016.12.040
    Database NAL-Catalogue (AGRICOLA)

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  2. Article: Reliability assessment of bioreactor landfills using Monte Carlo simulation and coupled hydro-bio-mechanical model

    Reddy, Krishna R / B. Munwar Basha / Girish Kumar / Rajiv K. Giri

    Waste management. 2017,

    2017  

    Abstract: The performance of a bioreactor landfill is highly influenced by the simultaneous interactions of several coupled processes that occur within the landfill. In addition, the high uncertainty and spatial variability in the geotechnical properties of ... ...

    Abstract The performance of a bioreactor landfill is highly influenced by the simultaneous interactions of several coupled processes that occur within the landfill. In addition, the high uncertainty and spatial variability in the geotechnical properties of municipal solid waste (MSW) poses significant challenge in accurately predicting the performance of bioreactor landfills. In this study, a 2D coupled hydro-bio-mechanical (CHBM) model was employed to predict the behavior of MSW in bioreactor landfills. The numerical model integrated a two-phase flow hydraulic model, a plane-strain formulation of Mohr-Coulomb constitutive model, and a first order decay biodegradation model. The statistical ranges (mean and standard deviation) of some of the major influential MSW properties were derived from the published studies. Random fields of spatially variable MSW properties were generated following the log-normal distribution. Reliability-based analysis was carried out by performing several realizations of Monte-Carlo simulations and the statistical response of the output results including the moisture distribution, pore fluid pressures, landfill settlement, and interface shear response of the composite liner system were quantified. The results clearly indicate the importance of considering spatial variability of the geotechnical MSW properties and its influence on the performance of bioreactor landfills during leachate injection operations. A comparison of the results with the deterministic analysis was performed to evaluate the relative benefits and to emphasize the need for reliability-based analysis for effective design of bioreactor landfills.
    Keywords biodegradation ; bioreactors ; landfills ; leachates ; lognormal distribution ; mathematical models ; Monte Carlo method ; municipal solid waste ; prediction ; uncertainty ; waste management
    Language English
    Size p. .
    Publishing place Elsevier Ltd
    Document type Article
    Note Pre-press version
    ZDB-ID 2001471-5
    ISSN 1879-2456 ; 0956-053X
    ISSN (online) 1879-2456
    ISSN 0956-053X
    DOI 10.1016/j.wasman.2017.11.010
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: Validation of Two-Phase Flow Model for Leachate Recirculation in Bioreactor Landfills

    Krishna R. Reddy / Rajiv K. Giri / Hanumanth S. Kulkarni

    Journal of Waste Management, Vol

    2014  Volume 2014

    Abstract: A numerical two-phase flow model is presented to determine the moisture distribution and pore water and gas pressures within unsaturated municipal solid waste (MSW) in bioreactor landfills during leachate recirculation. The numerical model used is the ... ...

    Abstract A numerical two-phase flow model is presented to determine the moisture distribution and pore water and gas pressures within unsaturated municipal solid waste (MSW) in bioreactor landfills during leachate recirculation. The numerical model used is the Fast Lagrangian Analysis of Continua (FLAC), which is based on finite difference approach. The model governing equations and mathematical formulations is briefly explained. Validation of the model is examined by simulating the published laboratory and field studies and published modeling studies. Overall, the two-phase flow model is found to produce results comparable with those of the published studies. This assures that the model can be used for the prediction of moisture distribution and for the rational design of leachate recirculation systems in bioreactor landfills.
    Keywords Environmental sciences ; GE1-350
    Language English
    Publishing date 2014-01-01T00:00:00Z
    Publisher Hindawi Publishing Corporation
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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