@article{faeli_montoya_gabr_2024, title={Development of a reactive transport model for microbial induced calcium carbonate precipitation in unsaturated conditions}, volume={3}, ISSN={["1208-6010"]}, DOI={10.1139/cgj-2022-06771}, journal={CANADIAN GEOTECHNICAL JOURNAL}, author={Faeli, Zahra and Montoya, Brina M. and Gabr, Mohammed A.}, year={2024}, month={Mar} }
 @article{faeli_montoya_gabr_2023, title={Development of a Reactive Transport Model for Microbial Induced Calcium Carbonate Precipitation in Unsaturated Conditions}, volume={61}, ISSN={0008-3674 1208-6010}, url={http://dx.doi.org/10.1139/cgj-2022-0677}, DOI={10.1139/cgj-2022-0677}, abstractNote={ Microbial induced calcium carbonate precipitation (MICP) offers a sustainable technique to improve geologic properties of soils in engineering structures. The applications encompass improved soil strength, scour mitigation, fracture sealing, and in situ contaminant immobilization. Previous studies have presented fundamental processes and implementation in lab- and field-scale. Most of these studies were examined in saturated conditions despite many MICP applications including those in coastal and riverside areas which will likely take place under unsaturated conditions. The study herein investigated the effect of soil water retention curve (SWRC) parameters and attachment coefficient ( Kat ) on CaCO3 precipitation in sand. Using numerical analyses, a continuum model was developed in which unsaturated flow and transport were coupled with biological and chemical reactions in variably saturated conditions. Predictive modeling results compare mass percentage of calcium carbonate resulting from MICP at degrees of soil water saturations of 20%, 40%, 80%, and 100% in sandy soil media. The results indicate the bacteria attachment coefficient increases by a factor of 3 as the degree of saturation is decreased from 100% to 20%, as the higher suctions at lower saturation levels improve bacteria fixation. The drying branch of SWRC versus wetting front yields higher CaCO3 for identical MICP treatment. Numerical results show the trend in hydraulic conductivity with increasing cementation level. }, number={4}, journal={Canadian Geotechnical Journal}, publisher={Canadian Science Publishing}, author={Faeli, Zahra and Montoya, Brina M. and Gabr, Mohammed}, year={2023}, month={Aug}, pages={827–835} }
 @article{faeli_montoya_gabr_2023, title={Elucidating factors governing MICP biogeochemical processes at macro-scale: A reactive transport model development}, volume={160}, ISSN={0266-352X}, url={http://dx.doi.org/10.1016/j.compgeo.2023.105514}, DOI={10.1016/j.compgeo.2023.105514}, abstractNote={Microbial Induced Calcium Carbonate Precipitation (MICP) influenced by biofilm metabolism in the subsurface can be exploited for a variety of engineered applications encompassing geotechnical ground improvement, environmental bioremediation, and hydraulic barriers. A reactive transport model was developed to determine the effects of controlling factors in terms of treatment protocols and experimental methods. Six column tests were calibrated and a range for the key parameters was determined. Fifteen key parameters of MICP reactive transport model were assessed in four categories (microbial activity and attachment, sample preparation, treatment protocol, and experiment dimensions). The results emphasized the effects of three main factors of microbial activity, microbial attachment process, and number of treatment (among all 15 assessed parameters) on the calcium carbonate (CaCO3) precipitation content and distribution. An increase in specific ureolysis rate (Ku) and attachment rate coefficient (Kat) by two orders of magnitude improves average CaCO3 by up to 13% and 6%, respectively with non-uniformity (COV) increase of 16%. Higher flow rates and solution concentrations contribute to more uniform CaCO3 distribution. The constant attachment rate model is useful to yield the CaCO3 precipitation profiles but more accurate models are needed to capture exact distribution. Post-treatment hydraulic conductivity, porosity and attached biomass were assessed.}, journal={Computers and Geotechnics}, publisher={Elsevier BV}, author={Faeli, Zahra and Montoya, Brina M. and Gabr, Mohammed A.}, year={2023}, month={Aug}, pages={105514} }
 @article{faeli_montoya_gabr_2023, title={Various Bacterial Attachment Functions and Modeling of Biomass Distribution in MICP Implementations}, volume={149}, ISSN={["1943-5606"]}, url={https://doi.org/10.1061/JGGEFK.GTENG-10812}, DOI={10.1061/JGGEFK.GTENG-10812}, abstractNote={Microbial induced calcium carbonate precipitation (MICP) offers a robust technique to improve strength and stiffness properties of subsurface soils supporting infrastructures. Several unknown factors, including the MICP reactive transport parameters, however, limit the ability to predict spatial distribution of calcium carbonate (CaCO3) precipitation within a subsurface area and with depth. As it was shown that calcium carbonate distribution is highly affected by biomass profiles in subdomains, five bacteria attachment models (constant-rate, power-law, exponential, gamma distribution, and "cstr based on colloid attachment theory") were calibrated here using data from both small- and large-scale testing programs. Out of the five models, colloid attachment theory with modified velocity and straining terms was shown to be the most promising approach in yielding the most fitted CaCO3 distribution compared with the experimental data. A new parameter, cstr, was incorporated to modify straining and the constraint peak value of biomass attachment due to straining at distances larger than a 0.14×sample size. Using the results from the numerical simulations, relationships were developed for velocity and straining coefficients of "the cstr based on colloid attachment theory" (hereafter "colloid attachment cstr") as a function of bacteria size, soil particle size, sample size, volume of injected bacteria, and soil pore volume.}, number={9}, journal={JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING}, author={Faeli, Zahra and Montoya, Brina M. and Gabr, Mohammed A.}, year={2023}, month={Sep} }
 @article{faeli_hosseini_gabr_pour-ghaz_2022, title={A new monitoring approach for sustainability assessment of subsurface utilities gasket materials against gasoline and chlorinated solvents: Field evaluation and model development}, volume={323}, ISSN={0301-4797}, url={http://dx.doi.org/10.1016/j.jenvman.2022.116217}, DOI={10.1016/j.jenvman.2022.116217}, abstractNote={Once installed, underground concrete pipes with rubber gaskets might be exposed to contaminated soil and groundwater. A pipe material monitoring capsule (PMMC) has been developed to evaluate volatile organic compounds (VOCs) breaking through three types of pipe gaskets; Neoprene, Buna-N, and Viton. The PMMCs were deployed in three contaminated sites: two with gasoline and one with chlorinated solvent (CS). A 3-D field-domain numerical model has been developed for each site to calibrate equivalent hydraulic parameters of each gasket material (ke, D) against benzene and PCE diffusion. The calibrated parameters were then used to compute the concentrations as well as rate of breakthrough of the two study contaminants. A protocol was developed for installing/retrieval of PMMCs to monitor PCE and benzene mass breaking through the gasket material with time. Employing PMMC, benzene concentrations breaking through the Neoprene and Buna-N after 4 months were approximately 70% and 60% respectively of the monitoring wells concentration. The corresponding value for PCE breakthrough after 4 months was 60% for both the Neoprene and Buna-N. Both gasket materials of Neoprene and Buna-N yielded similar performances, including higher rate of contaminant breakthrough compared to Viton. A nonlinear relationship of mass breaking through the gaskets of benzene and PCE with time was discerned from the modeling and field data.}, journal={Journal of Environmental Management}, publisher={Elsevier BV}, author={Faeli, Zahra and Hosseini, Payam and Gabr, Mohammed A. and Pour-Ghaz, Mohammad}, year={2022}, month={Dec}, pages={116217} }
 @article{alhomair_faeli_hosseini_gabr_pour-ghaz_parker_2021, title={Assessment of Mitigation Measures against Benzene Breakthrough into Subsurface Concrete Pipe}, volume={12}, ISSN={["1949-1204"]}, DOI={10.1061/(ASCE)PS.1949-1204.0000512}, abstractNote={AbstractWork in this paper investigates the efficacy of mitigation measures to minimize the contaminant ingress into subsurface concrete pipes. The 3D study model of the concrete pipe and the soil ...}, number={1}, journal={JOURNAL OF PIPELINE SYSTEMS ENGINEERING AND PRACTICE}, author={Alhomair, Sultan and Faeli, Zahra and Hosseini, Payam and Gabr, Mohammed and Pour-Ghaz, Mohammad and Parker, Cyrus}, year={2021}, month={Feb} }
 @article{faeli_alhomair_hosseini_gabr_pour-ghaz_2021, title={Factors Affecting Multiphase Benzene Breakthrough into Drainage Concrete Pipe in the Unsaturated Subsurface Profile}, volume={12}, ISSN={["1949-1204"]}, DOI={10.1061/(ASCE)PS.1949-1204.0000554}, abstractNote={AbstractAnalyses presented herein explore transport aspects related to benzene breakthrough into gasketed subsurface concrete pipe embedded in an unsaturated soil profile. A series of three-dimensi...}, number={3}, journal={JOURNAL OF PIPELINE SYSTEMS ENGINEERING AND PRACTICE}, author={Faeli, Zahra and Alhomair, Sultan and Hosseini, Payam and Gabr, Mohammed and Pour-Ghaz, Mohammad}, year={2021}, month={Aug} }
 @article{hosseini_alhomair_faeli_pour-ghaz_gabr_knappe_parker_2020, title={Degradation Model for the Tensile Strength of PVC and Rubber Gasket Materials Exposed to Benzene and PCE-Saturated Aqueous Solutions}, volume={2674}, ISSN={["2169-4052"]}, DOI={10.1177/0361198120906126}, abstractNote={ In this paper, a tensile strength degradation model is developed for polyvinyl chloride (PVC) pipe and three rubber gasket materials commonly used in stormwater drains and wet utilities; the degradation model considers exposure to a single contaminant at its saturation level. The contaminant considered included benzene and tetrachloroethylene (PCE) because of their prevalence. The materials considered are unplasticized Polyvinyl chloride (u-PVC) utilized as the pipe material, and three types of rubber gaskets: Polychloroprene (Neoprene-CR), Acrylonitrile (nitrile) butadiene rubber (Buna-N), and fluoroelastomer rubber (FKM—Grade A VitonTM). First, the degradation rates of these materials are experimentally quantified using accelerated testing; then using the experimental results and Williams–Landel–Ferry (WLF) method a degradation model is developed. Finally, a simplified method is introduced to relate the tensile strength degradation of PVC to the penetration rate of the contaminants. }, number={2}, journal={TRANSPORTATION RESEARCH RECORD}, author={Hosseini, Payam and Alhomair, Sultan and Faeli, Zahra and Pour-Ghaz, Mohammad and Gabr, Mohammed and Knappe, Detlef and Parker, Cyrus}, year={2020}, month={Feb}, pages={274–283} }