Browsing by Author "Cobb, Holly"
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Item DEVELOPMENT OF AN ENGINEERED TREATMENT SYSTEM FOR THE REMEDIATION OF BRINE-CONTAMINATED SOILS(University of Delaware, 2023-05) Cobb, HollyProduced water is a highly concentrated brine produced during the extraction of oil and natural gas from geological formations. When spilled, it threatens nearby vegetation and groundwater. The current way of dealing with produced water spills is to excavate the impacted soil and send it to a specialized landfill. This study is concerned with the lab-scale development of an engineered system to remediate salt contamination from produced water spills. Evaporative flux is the process where water passes upward through soil as it evaporates at the surface, carrying solutes with it. Crystallization modifiers are compounds that alter the precipitation of minerals, delaying the onset of crystallization and/or modifying crystal habit, until salts approach or emerge at the surface. Evaporative flux and crystallization modifiers provide the basis for the design evaluated herein, where a constant supply of treatment solution consisting of water and crystallization modifier is supplied at the base of contaminated soil and transports through soil via evaporative flux. A remediation system was devised in the lab based upon these ideas, where a Mariotte bottle which exerts a constant hydraulic head on the system is connected to a beaker containing a 3cm depth of contaminated soil. To create a brine-contaminated soil, a 3.8M salt solution saturates a loamy sand followed by oven drying. This contaminated soil was passively flushed with treatment solution containing various concentrations of a crystallization modifier for five days, before being dried and analyzed by depth. The electrical conductivity of each depth layer of the soil column was collected to understand where the salt was removed and where it remained. Lab-scale experiments show up to 96% removal using a 3mM potassium ferrocyanide solution. Experiments testing the ideal dosage and application of crystallization modifier, the potential use of fabrics to harvest salts, and the impact of using real produced waters were evaluated to improve this system before it is repeated at pilot scale.