Experimental and numerical investigations of conceptual models for biological clogging of unsaturated soils

logging in the unsaturated zone is an important issue in the field of septic systems and biofilters. Different conceptual models for clogging in the saturated zone were proposed in the literature but corresponding conceptual models for clogging in the unsaturated zone are limited.;The objectives of this research were to further investigate and understand the processes that govern biological clogging in unsaturated soils. Through a detailed experimental study and numerical modeling, the goal was to further develop and validate these conceptual models using experimental data.;This research was divided into three stages. First stage involved an experimental study to determine the effect of different pore structures on the bioclogging process and to generate valuable data to be used in stage three. The second stage aimed to evaluate Monod kinetic parameters for the clogging process studied in stage one. The third stage aimed to improve upon and validate the three conceptual models proposed earlier by Mostafa and Van Geel (2007) using the experimental data generated in stages one and two.;Soil and Monod kinetic parameters measured/estimated in stages one and two were used to calibrate the numerical code. The calibration process revealed that a more detailed numerical model was needed to simulate the clogging process observed in stage one. Modifications were conducted on the numerical code which included the addition of new top head boundary condition to simulate ponding and a more detailed conceptual model to represent microbial growth to include EPS and an inert fraction.;Mostafa and Van Geel (2007) proposed three conceptual models to relate the relative permeability of unsaturated soils to microbial growth. The three models were implemented in a one-dimensional numerical code and hypothetical scenarios were simulated to verify that the equations were coded correctly. No laboratory or field data were used to validate the three conceptual models.;After the modifications were conducted, the three conceptual models were used to simulate bioclogging process. Based on the results, a conclusion was drawn that Models...