In this project, we will develop computational tools for modeling the complex interactions between the microbiological, architectural, and mechanical properties of bacterial biofilms. The tools will combine models for multi-species biofilm growth and development, elasticity properties that depend on the different species and their products, e.g. EPS, and the interaction of the biofilm with overlying fluid flow. As a test case, the tools will be used to study the behavior of heterotroph/autotroph two-species biofilms commonly used for nitrogen removal in activated sludge reactors. These biofilms exhibit complex behavior in their tendency to develop stratified colonies where the fast growing heterotrophs cover the slow growing and brittle autotrophs. The heterotrophs protect the autotrophs from fluid stresses, and also consume the products generated by the autotrophs as they remove nitrogen from wastewater.
Biofilms are a ubiquitous form of life that impact humans in many ways. Biofilms are responsible for nitrogen loss from agricultural fertilizers, deplete oxygen in streams, cause disease in humans and plants, and foul pipes, heat exchangers, and ship hulls. It is estimated that biofilms cost the U.S. billions of dollars annually in equipment and product damage, energy losses, and human infections. The tools developed in this project will be general enough to be applied to a wide range of multi-species biofilm communities, and will be useful in improving our understanding of these complex systems. In this project, the tools will be applied to activated sludge reactors, which are systems used for the treatment of wastewater. In this system, bacteria and other microorganisms remove harmful substances for purposes of water reclamation. For maximal efficiency of these reactors, the right balance of autotrophic and heterotrophic bacteria must be found. The tools developed in this project will improve our understanding of this system and aid in the identification of the optimal operating conditions.
