EAGER: Feasibility Study of Micro-Level Sensing and Process Control of Nitrification

Columbia University, New York NY

Investigators

Abstract

1025685 Attinger Intellectual merit The aim of this project is to prove the concept that microbioreactors with integrated "on-chip" sensing can investigate the process kinetics of microorganisms under a wide array of shear stress and mass transport conditions. This microbioreactor concept will allow the study of low shear stress in combination with fast mass transport, conditions that are not attainable in current larger bench scale reactors. The target microorganisms investigated in this project are nitrifying bacteria. These bacteria sequentially oxidize ammonia to nitrite and nitrate and thus render it amenable for subsequent reduction to dinitrogen gas. Nitrifying bacteria play an important role in both natural and engineered environments due to their role in the global nitrogen cycle, for instance in relation to waste management. Microbioreactors have inherent, transformative advantages over currently used benchscale reactors. They feature more homogeneous flow conditions than larger reactors, direct optical access and large surface to volume ratio, for enhanced mass transfer. For instance, permeable membranes are used for gas diffusion, rather than traditional bubbling techniques that come with increases in shear stress. Control and measurement of nitrite concentration and temperature will be implemented using optical and microfabrication techniques. Broader impact The PIs will disseminate the results in their graduate course "Microscale Transport Phenomena". Undergraduate and High School students will be involved in this interdisciplinary research, a practice that is customary to the research laboratories of both the PI and co-PI. This exploratory research will provide a foundation for the submission of a full size proposal to engineer nitrifying bioreactors for wastewater treatment, effectively overcoming currently observed mass-transfer limitations. This research will integrate into synergistic activities of Columbia University with industry (IBM "Smarter Cities") and with the Department of Chemical Engineering to grow this effort into a possible NSF research Center.