Dr. Fabrizio Sabba
Department of Civil and Environmental Engineering
Biofilm processes are increasingly used for wastewater treatment, especially for nutrient removal, but their behavior is highly complex, due to substrate gradients and microbial stratification. Mathematical modeling is key to understanding this complex behaviour and allow more effective and sustainable applications. For example, modeling and experiments were used to investigate the formation nitrous oxide (N2O), a potent greenhouse gas, from nitrifying and denitrifying biofilms. The results suggested that N2O emissions could be significantly greater in biofilms due to the diffusion of hydroxylamine, a nitrification intermediate, from aerobic to anoxic zones of the biofilm. As second example, elemental sulfur (So), a resource that can be recovered at no cost as a waste product, can serve as a more sustainable and cost effective electron donor for biofilm-based denitrification, yet few researchers have considered its behavior as a counter-diffusional biofilm. A biofilm model was developed to predict trends for nitrate fluxes, and investigated nitrite accumulation in So‐based denitrification biofilms. A key finding was thin biofilms performed poorly due to biomass limitation, but thick biofilms behaved poorly due to mass transfer limitations. Thus, biofilm management is critical to optimize So‐based denitrification. These results indicate the importance of coupling experimental and modeling work to advance the effective use of biofilm processes
Dr. Sabba is a Postdoctoral Fellow in the Department of Earth and Planetary Sciences at Northwestern University. He obtained his Ph.D. in Environmental Engineering from the University of Notre Dame in 2016, then worked as Director of Research and Development for NUVODA, a wastewater firm in Blacksburg (Virginia) for one year. In 2018, he joined Northwestern University as a Postdoctoral Fellow in the Department of Civil and Environmental Engineering. Dr. Sabba’s research interests include biological processes for nutrients removal and resource recovery during water and wastewater treatment, and nitrogen cycle in the deep terrestrial subsurface, with a special focus on biofilm processes.