Ms. Dworatzek is an environmental microbiologist and Principal Scientist at SiREM and has been with the company for seventeen years. She has conducted and overseen numerous studies examining enhanced in situ remediation in groundwater and has specific technical experience in the scale up of growth of microbial cultures for bioaugmentation laboratory and field pilot tests, and evaluation of bioremediation, zero valent iron and chemical oxidation technologies in the laboratory. She currently oversees maintenance and culturing of KB-1® and KB-1® Plus dehalorespiring microbial cultures as well as the development of new bioaugmentation cultures including 1,4-dioxane, 1,2,3-trichloropropane, and BTEX.
Bioaugmentation Approaches for 1,4-Dioxane Bioremediation
Bioaugmentation Approaches for 1,4-Dioxane Bioremediation Sandra Dworatzek, Jennifer Webb, Alicia Hill (SiREM, Guelph, Ontario) Beau Hodge (Geosyntec, Raleigh, NC) Bioremediation is a promising approach for remediation of 1,4-dioxane in groundwater. However, 1,4-dioxane presents some specific challenges for successful enhanced in-situ bioremediation (EISB) compared to many chlorinated solvents including generally low groundwater concentrations, high mobility, inhibitory effects of co-contaminants and stringent drinking water regulations. For 1,4-dioxane, co-contamination with chlorinated solvents presents a particular challenge as these compounds tend to inhibit aerobic 1,4-dioxane degradation. To better understand the challenges and potential for bioremediation of 1,4-dioxane, bench-scale testing has been completed to: demonstrate a variety of EISB approaches for 1,4-dioxane and to identify the conditions and treatments associated with successful outcomes, as well those that were ineffective or negatively affected outcomes. Prior to field implementation, bench-scale testing has demonstrated that both aerobic metabolic and cometabolic degradation of 1,4-dioxane is feasible and that bioaugmentation is often an important tool for enhancing biodegradation of this compound. For a site in North Carolina, a bench-scale study demonstrated that anaerobic degradation of chlorinated solvents was required prior to aerobic 1,4-dioxane degradation being feasible. In this study, aerobic 1,4-dioxane degradation was inhibited by the presence of milligram per liter concentrations of chloroform (CF). Addition of an electron donor and bioaugmentation (KB-1® Plus CF formulation) resulted in CF degradation, with both CF and its daughter product dichloromethane being reduced to non-detect concentrations. After which aerobic conditions were reestablished, and the microcosms were bioaugmented with a 1,4-dioxane degrading consortia. 1,4-dioxane concentrations then declined from 4 mg/L to less than 25 ug/L. This study demonstrated the benefits of bioaugmentation and the ability to utilize both aerobic and anaerobic pathways to degrade 1,4 -dioxane and to achieve a positive outcome. Field demonstration of an aerobic metabolic 1,4-dioxane bioaugmentation culture in a low concentration 1,4-dioxane plume is scheduled for late 2019. Updates from this pilot test will be presented to provide further insights into the use of bioaugmentation as tool for remediation of this challenging emerging contaminant.