Caitlyn Butler

Associate Professor

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.  

Current Research

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

Academic Background

  • Ph.D., Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 2010.
  • B.S. Engineering Science, Smith College, 2004mn
Abouhend, A.S., McNair, A., Kuo-Dahab, W.C., Watt, C., Butler, C.S. Milferstedt, K. Hamelin, J. Seo, J. Gikonyo, JG, El-Moselhy, K.M., and Park, C. The Oxygenic Photogranule Process for Aeration-Free Wastewater Treatment, Environmental Science & Technology Vol. 52, Issue 6, 3503-3511, 2018 DOI: 10.1021/acs.est.8b0040
Kuo-Dahab, W.C., Stauch-White, K., Butler, C.S., Gikonyo, G., Carbajal-Gonzlez, B., Ivanova, A., Dolan, S., and Park, C., Investigation of the fate and dynamics of extracellular polymeric substances (EPS) during sludge-based photogranulation under hydrostatic conditions, Environmental Science Technology, Accepted 2018, DOI: 10.1021/acs.est.8b0303
Milferstedt, K., Kuo-Dahab, W.C., Butler, C.S., Hamelin, J., Abouhend, A.S., Stauch-White, K., McNair, A., Watt, C., Carbajal-González, B.I., Dolan, S., and Park, C. The importance of filamentous cyanobacteria in the development of oxygenic photogranules. Scientific Reports Vol. 7, No. 17944., 2017, doi: 10.1038/s41598-017-16614-9
Stauch-White, K., Srinivasan, V.N., Camilla Kuo-Dahab, W., Park, C., and Butler, C.S. The role of inorganic nitrogen in successful formation of granular biofilms for wastewater treatment that support cyanobacteria and bacteria. AMB Express Vol. 7, No. 146, 2017
Srinivasan, V., and Butler, C.S., Ecological and Transcriptional Responses of Anode-Respiring Communities to Nitrate in a Microbial Fuel Cell, Environmental Science & Technology, Vol. 51, No. 9, 5334-5342, 2017
Butler, C.S. and Lovley, D., How to Sustainably Feed a Microbe: Strategies for Biological Production of Carbon-Based Commodities with Renewable Electricity, Frontiers in Microbiology, Vol. 7, No. 1879, 2016
Castro, C., Srinivasan, V., and Butler, C.S., Electricity and Methane Production in a Pilot Scale Microbial Fuel Cell Treating Synthetic and Real Wastewater, IWA Water Sanitation and Hygiene, Vol. 6, No 4, 613-621, 2016
Lau, B. and Butler, C.S., Censored at the Nanoscale, Frontiers in Microbiology, Vol. 7, No. 253, February 2016
Srinivasan, V., Weinrich, J., Butler, C.S., Nitrite-Accumulation in a Denitrifying Biocathode, Environmental Science: Water Research and Technology, 2016, 2, 344-352
Contact Info

Civil and Environmental Engineering
18B Marston Hall
130 Natural Resource Center Way
Amherst, MA 01003-9292

(413) 545-5396