(56o) Effects of Anaerobic Environment in Water Quality Downgradient of a Mulch Biowall

Authors: 
Kumar, A., Texas A & M- Kingsville
Alexander, M. L., Texas A&M University-Kingsville
The biowall is one of the permeable reactive barrier techniques used in environmental remediation. A biowall is used for the treatment of the chlorinated solvent contaminants in groundwater. It helps to prevent contaminant discharge from a groundwater plume into surface water or other downgradient receptors. Contaminants, such as chlorinated solvents, are treated within the biowall or immediately downgradient of the biowall. A biowall is made up of a carbon source which is organic in nature. This carbon source promotes anaerobic reductive dechlorination of chlorinated contaminants. Organic material that may be used includes wood mulch or waste plant material and liquid organic material such as vegetable oil or other long chain fatty acids. Anaerobic conditions are created when oxygen is consumed. Additionally, if the water contains a moderate to high amount of sulfate, then the anaerobic conditions lead to the formation of sulfides. The objective of this work is to investigate the concentration of total organic carbon (TOC), sulfate and sulfide by the laboratory experiments and modeling. The laboratory experiments consist of a column test conducted to mimic a biowall. This includes sulfide and sulfate measurement using spectrophotometer absorbance after reacting sample with the reagent chemicals. The second part includes modeling to fit the experimental data. The modeling simulation includes solving the set of partial differential equations obtained from mass balance of different chemical species like cellulose, glucose, lactic acid, and changes in the concentration of sulfate and sulfide using MATLAB. The various model constant parameters, such as the initial concentration of glucose, sulfate, reaction rate constant and velocity are assumed during the modeling simulation. Concentration changes for biomaterials and compounds are compared based on time and distance parameters.