Engineered Bioremediation of Trichloroethylene Contaminated Aquifer Using Emulsified Vegetable Oil Injection

Abstract

Trichloroethylene (TCE) contamination in groundwater aquifers poses significant environmental and public health risks due to its toxicity, persistence, and widespread use in industrial degreasing operations. This study investigates the engineered bioremediation of TCE-contaminated aquifers through the injection of emulsified vegetable oil (EVO) as an electron donor to stimulate anaerobic microbial degradation processes. The research focuses on evaluating contaminant removal efficiency, microbial activity enhancement, and hydrogeochemical changes occurring during in situ remediation. Experimental and field-scale analyses were conducted to examine the influence of EVO concentration, injection strategy, groundwater flow conditions, nutrient availability, and redox potential on TCE degradation performance. Results demonstrated that emulsified vegetable oil effectively promoted reductive dechlorination by creating favorable anaerobic conditions for indigenous dechlorinating microorganisms. Significant reductions in TCE concentration were observed along with the sequential formation and degradation of intermediate chlorinated compounds, indicating active biodegradation pathways within the aquifer system. The sustained release of organic carbon from EVO enhanced microbial metabolism and prolonged treatment effectiveness over extended operational periods. Kinetic evaluation revealed that contaminant degradation rates were strongly influenced by substrate distribution, microbial adaptation, and groundwater transport characteristics. Hydrogeochemical monitoring confirmed stable reducing conditions and improved biodegradation efficiency following EVO injection. Compared with conventional pump-and-treat remediation methods, the engineered bioremediation approach offered lower operational costs, reduced energy requirements, and minimal disturbance to subsurface environments. The findings highlight the potential of emulsified vegetable oil injection as an effective and sustainable strategy for in situ remediation of chlorinated solvent-contaminated groundwater systems and support its application in environmental restoration and groundwater management practices.