Modelling leachate-induced clogging of porous media

2012 ◽  
Vol 49 (8) ◽  
pp. 877-890 ◽  
Author(s):  
Yan Yu ◽  
R. Kerry Rowe
Keyword(s):  
Porous Media ◽  
Numerical Model ◽  
Direct Contact ◽  
Drainage Layer ◽  
Granular Filter ◽  
Leachate Collection ◽  
Mesocosm Experiments ◽  
Observed Behaviour ◽  
Coarse Gravel ◽  
Waste Leachate

A numerical model to predict biologically induced clogging of municipal solid waste leachate collection systems is described. The model simulates the accumulation of clog mass in the porous media by the growth of biomass and precipitation of minerals. In addition, the settling and deposition of suspended particles is modelled. A technique for modelling filter-separator layers between the waste and the coarse granular drainage material is described. The application of the model is illustrated for two series of laboratory mesocosm experiments: one where the waste was in direct contact with the underlying drainage layer and the second where there was a granular filter between the waste and the coarse gravel drainage layer. The modelling shows that the clogging of the gravel in the lower regions of the saturated drainage layer is estimated better by the advanced numerical model than the previously published model. In both cases, the calculated results are in encouraging agreement with the observed behaviour. It is concluded that this model has potential for use in modelling biologically induced clogging of municipal landfill leachate collection systems.

Effect of filter–separators on the clogging of leachate collection systems

2006 ◽  
Vol 43 (7) ◽  
pp. 674-693 ◽  
Author(s):  
Reagan McIsaac ◽  
R Kerry Rowe
Keyword(s):  
Hydraulic Conductivity ◽  
Thick Layer ◽  
Sand Layer ◽  
Drainage Layer ◽  
Granular Filter ◽  
Leachate Collection ◽  
Mesocosm Experiments ◽  
Nonwoven Geotextile ◽  
Geotextile Filter ◽  
Waste Leachate

This paper reports the results obtained after 6 years operation of nine mesocosm experiments that simulate the 50 cm of the drainage layer closest to the leachate collection pipe in a landfill. Five different design configurations were examined involving a 300 mm thick layer of coarse (38 mm) gravel. The designs differed in terms of the presence, nature, and location of a filter–separator layer either at the waste–gravel interface or partway through the gravel. A nonwoven geotextile filter–separator (GTF/S) is shown to reduce clogging of the gravel relative to the no filter–separator or woven GTF/S designs. Some clogging of the geotextiles is reported, with reductions in geotextile hydraulic conductivity of 23% for the woven GTF/S, 74%–89% for the nonwoven GTF/S, and 75%–94% for the nonwoven geotextile partway through the gravel. The clogged nonwoven geotextile filter–separator maintained a higher hydraulic conductivity than the extracted woven geotextile. Of the designs with a filter–separator between the waste and gravel, the granular filter–separator most effectively reduced clogging of the gravel but at the expense of leachate mounding above the sand once the sand layer clogs. The design with a nonwoven geotextile partway through the gravel (GTMF) provides better protection of the underlying gravel from clogging than other designs involving a geotextile.Key words: landfill, waste, leachate, clogging, biofilm, geotextile.

Numerical Simulation of Insulin Depot Formation and Absorption in Subcutaneous Tissue Modeled as a Homogeneous Anisotropic Porous Media

2021 ◽  
Author(s):  
Michael Zedelmair ◽  
Abhijit Mukherjee
Keyword(s):  
Porous Media ◽  
Numerical Model ◽  
Insulin Pump ◽  
Subcutaneous Tissue ◽  
Saturated Porous Media ◽  
Anisotropic Porous Media ◽  
Effective Option ◽  
Computational Fluid Dynamics Cfd ◽  
Experimental Findings ◽  
Subcutaneous Adipose

Abstract In this study, a numerical model of the insulin depot formation and absorption in the subcutaneous adipose tissue is developed using the commercial Computational Fluid Dynamics (CFD) software. A better understanding of these mechanisms can be helpful in the development of new devices and cannula geometries as well as predicting the concentration of insulin in the blood. The injection method considered in this simulation is by the use of an insulin pump using a rapid acting U100 insulin analogue. The depot formation is analyzed running Bolus injections ranging from 5-15 units of insulin corresponding to 50-150µl. The insulin is injected into the subcutaneous tissue in the abdominal region. The tissue is modeled as a fluid saturated porous media. An anisotropic approach to define the tissue permeability is studied by varying the value of the porosity in parallel and perpendicular direction having an impact on the viscous resistance to the flow. Following recent experimental findings this configuration results in a disk shaped insulin depot. To be able to run the simulation over longer timeframes the depot formation model has been extended implementing the process of absorption of insulin from the depot. The developed model is then used to analyze the formation of the insulin depot in the tissue when using different flow rates and cannula geometries. The numerical model is an effective option to evaluate new cannula designs prior to the manufacturing and testing of prototypes, which are rather time consuming and expensive.

Numerical modeling of clogging of landfill leachate collection systems with co-disposal of municipal solid waste (MSW) and incinerator ash

2021 ◽  
Vol 58 (1) ◽  
pp. 83-96
Author(s):  
Yan Yu ◽  
R. Kerry Rowe
Keyword(s):  
Porous Media ◽  
Service Life ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Fate And Transport ◽  
Operating Period ◽  
Leachate Collection ◽  
Incinerator Ash ◽  
Concentrated Source ◽  
Mass Volume

The influence of co-disposal of municipal solid waste (MSW) and incinerator ash used as daily cover on the clogging of leachate collection systems (LCSs) from landfills is examined. The “BioClog” model is used to simulate the fate and transport of the nine leachate constituents most responsible for clogging the LCSs as they move through the porous media. It then calculates the thicknesses of five films that attach to the porous media and the effect of this clog mass–volume on the porosity and hydraulic conductivity of the granular material. Then it models the consequent growth in the leachate mound with increasing clog mass over time until the service life of the LCS is reached. The modeling shows that the concentrated source of leachable minerals in the incinerator ash accelerates the clogging rate and reduces the service life of the LCSs compared to inert daily cover. If an LCS is not designed to accommodate these higher concentrations of cations in the influent leachate during the landfill operating period, the ash can significantly reduce the LCS service life. Means of extending LCS service life are discussed. A practical technique is also utilized to estimate the service life of LCSs with conservative and reasonable agreement with BioClog.

Numerical Model of Complex Porous Media

2002 ◽  
Author(s):  
Andre´ Chambarel ◽  
Herve´ Bolvin
Keyword(s):  
Porous Media ◽  
Numerical Model ◽  
Physical Properties ◽  
Space Distribution ◽  
Partial Differential ◽  
Differential Problem ◽  
Classical Models ◽  
Element Approach ◽  
Statistical Approaches ◽  
Percolation Phenomenon

In complex porous media we often notice a percolation phenomenon [KIR 71] [GRI 89]. Usually these media present discontinuous characteristics and a random space distribution [LET 00] [BIR 95]. There results that the classical models based on the resolution of a partial differential problem become inefficient because we have non-derivable function [MAU 01]. Statistical approaches based on the resolution of partial differential problems pose notably the questions concerning the continuity of the functions representing the physical properties of the medium. In this work we propose to study a numerical model of porous media based on a mixture of 2 components in a percolation context. In practice, the main difficulty is based on the complex physical properties. We present also a model of homogenization. Our numerical model is based on the Finite Element approach.

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