CIVIL ENGINEERING 365 ALL ABOUT CIVIL ENGINEERING



AbstractThis research presents a numerical investigation that employs a continuous adsorptive barrier (CAB) near heavily contaminated groundwater. The source is classified as a heavy metal finite point source that is found in landfills. A decision maker could benefit from the CAB design charts that are produced in this research in table and chart forms. Based on the results, the cost of the barrier installation (CCAB) and the estimated dimensions could be determined by a decision maker for a known finite source concentration at the site. To accomplish this, the problem is simplified and discretized using the finite-difference technique to solve a two-dimensional (2D) transport model, and the model’s accuracy is then tested against a variety of real-world scenarios. The established model (PRBFD) was used to simulate heavy metal pollution that used adsorption as the natural attenuation. Later, the required aquifer length and width for a 4-year simulation were plotted. Then, it was discovered that natural remediation took longer to reach the remediation goal, and therefore, to meet the requirements, a reactive barrier was considered. Zero-valent iron (ZVI), which is a reactive material, is introduced next to the contaminant to absorb heavy metals in a CAB. Subsequently, a plot of the maximum relative concentrations in the longitudinal and transverse directions is generated from the data for peak concentrations that are obtained at various time (t) intervals, and the requisite CAB dimensions [e.g., length (LB) and width (WB)] are computed where the cost incurred in the system is calculated. Finally, a sensitivity analysis is performed to determine the impact of sensitive hydraulic parameters on the barrier dimensions and its design cost, and various design charts are generated for the most probable cases, which could allow a decision maker to identify the barrier dimensions for any known source concentration value.Practical ApplicationsA number of heavy metals, such as arsenic (As), lead (Pb), zinc (Zn), copper (Cu), and cadmium (Cd) adversely affect human health. Toxic metals could easily be transmitted to the human body by food or water, because heavy metals naturally transfer from the soil to crops and then into groundwater. This research was designed so that a decision maker could determine the size of the reactive barrier, along with the design cost, against known maximum concentrations of hazardous metals at the source; and permissible concentrations of the same metal contaminant at the barrier exit face without the use of mathematical modeling.



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