I explore unique biofilm systems that rely on counter-diffusional gradients and their applications, primarily, in the treatment of environmental contaminants. In conventional biofilms, electron donors and electron acceptors diffuse from one side of the biofilm . Microbial activity decreases quickly as substrates are depleted near the surface. In a counter-diffusional biofilms, the electron donor and acceptor diffuse in from opposite sides, fundamentally changing the functional properties and microbial ecology. The optimal microbial activity is concentrated in the center of the biofilm and more evenly distributed across the biofilm. An example of these biofilms include cathode-oxidizing biofilms where electrons via e- carriers diffuse into the biofilm from the electrode to which the microorganisms are attached and electron acceptors, such as oxygen or nitrate, diffuse from bulk liquid. Another example, in oxygenic photogranules (OPGs), phototrophs cooperate with a variety of bacterial populations to create a network of counter-diffusional gradients which sustain the symbioses in these granules.
I am particularly interested in biofilm systems with opportunities for resource recovery such as bioelectrochemical systems (BESs) where some of the chemical potential in wastes and wastewater can be converted to electrical energy and granular, phototrophic biofilms that when done treating wastewater have potential to be a biofuel or biogas feedstock. Energy-efficiency and resource recovery could yield cost-savings in centralized treatment systems but also, could have applications as small, low-maintenance decentralized systems in developing areas.
Fundamentally, I seek to link the behavior and microbial ecology of these biofilms at the microscale to the outcomes at the environmental system-scale, i.e. meso- or macroscale. I begun expanding my research to other systems including the fate and transport of nanoparticles in biofilms, soil biofilms that interface with decentralized treatment strategies, include septic systems and urine compost, and biofilms that grow in the Greenland Ice Sheet.
Learn more at blogs.umass.edu/csbutler
- Ph.D., Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 2010.
- B.S. Engineering Science, Smith College, 2004mn