Emerging Contaminants Summit

Spring 2020

sambrottoRaymond Sambrotto
Lamont Associate Professor
Columbia University

Ray Sambrotto is the founder of Allied Microbiota, a company that uses bacteria and other microbes to address problems of environmental contamination, waste processing and energy storage. AMB’s initial work on the degradation of organics in soils and sediments has been tested in several large-scale pilot tests and is now at the commercialization stage. He directs additional research and development on extensions of the bioremediation approach to the groundwater matrix. Sambrotto has been an environmental microbiologist for 30 years and brings his familiarity with the global biodiversity of microbial features to bear on current environmental challenges.



Bioremediation of 1,4-Dioxane in Bioreactors Using Thermophilic Bacteria

Co-Author Frana James, Allied Microbiota

The role of solvent additives such as 1,4-dioxane as a contaminant of groundwater, and the resistance of its removal by in-situ means, motivates a search for appropriate remediation technologies. This research focuses on above ground treatment options using a unique thermophilic bacterium we envision as suitable for a bioreactor remediation protocol. The strain grows at temperatures of 40-65˚C (105-150˚F) and degrades 1,4-dioxane readily in the presence of oxygen. Degradation rates of 9-11%/hr have been achieved in shake flask experiments. Among the challenges involved in adapting this suspended cell process to the ex-situ processing of groundwater, is the maintenance of the high rates of 1,4-dioxane destruction through time. Efforts have focused on a fixed bed of bacteria that maintain high degradation activity and there are two key focal points for optimization as follows.

Nutrient Formulation: The degradation process is co-metabolic and requires periodic input of liquid substrate to maintain cell activity, a process that can easily be automated. This could be an advantage over systems that require gas infusion, as is the case with propane and propranotrophs, that may be more difficult to engineer. Physical Substrate Development: Microscopic observations indicate that bacteria attach to surfaces by the apex of the cell and do not form thick biofilms. On this basis, initial tests with packed columns of glass beads were successful, but difficult to maintain for extended periods. Recent efforts therefore have focused on softer support materials that are inexpensive. The results of testing with support materials such as polyurethane and cellulose fibers will be presented.

The data from these tests are being used to estimate scale-up efficiencies for appropriately-sized bioreactors. We envision one important practical application to be the management of field sites where more complex treatment processes such as AOP or resin absorbtion might be economically more challenging.

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