title: One-dimensional model for biogeochemical interactions and permeability reduction in soils during leachate permeation.
abstract: This paper uses the findings from a column study to develop a reactive model for exploring the interactions occurring in leachate-contaminated soils. The changes occurring in the concentrations of acetic acid, sulphate, suspended and attached biomass, Fe(II), Mn(II), calcium, carbonate ions, and pH in the column are assessed. The mathematical model considers geochemical equilibrium, kinetic biodegradation, precipitation-dissolution reactions, bacterial and substrate transport, and permeability reduction arising from bacterial growth and gas production. A two-step sequential operator splitting method is used to solve the coupled transport and biogeochemical reaction equations. The model gives satisfactory fits to experimental data and the simulations show that the transport of metals in soil is controlled by multiple competing biotic and abiotic reactions. These findings suggest that bioaccumulation and gas formation, compared to chemical precipitation, have a larger influence on hydraulic conductivity reduction.
authors.affiliation: Department of Civil and Environmental Engineering, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. n.singhal@auckland.ac.nz
authors.forename: Naresh
authors.initials: N
authors.lastname: Singhal
authors.forename: Jahangir
authors.initials: J
authors.lastname: Islam
mesh_terms: D001669:Biochemical Phenomena; D001671:Biochemistry; D001673:Biodegradation, Environmental; D018533:Biomass; D002138:Calibration; D003198:Computer Simulation; D005740:Gases / Q000737:chemistry / Q000378:metabolism; D055593:Geological Phenomena; D005844:Geology; D007700:Kinetics; D008954:Models, Biological; D012987:Soil; D012988:Soil Microbiology; D012996:Solutions
chemical_list: D005740:Gases; D012987:Soil; D012996:Solutions