North Carolina State University, Ph.D.
Francois Fiessinger Scholar 2004
Changes in Microbial Community Structure in Solid Waste Decomposition
Where Are They Now? Bryan is currently the President and Chief Executive Officer at the Environmental Research & Education Foundation.
Project Description (while EREF Scholar):
Bryan’s research focused on how landfill microbiology impacts refuse decomposition in landfills. While a good understanding of the microbial populations involved in refuse decomposition and their basic function had been developed, the mechanics of how specific microbial species vary with time and how this variation might impact the stability and rate of refuse decomposition has not been previously evaluated. By assessing microbial function and metabolism, it is hoped that new strategies can be developed that will enhance refuse decomposition and methane recovery.
This research focused on examining the landfill system from an ecological perspective, looking at the level of diversity amongst fermentative, cellulolytic, acetogenic and methane-producing bacteria. The aim of the research was to assess reasons for population shifts over time, evaluate the importance of such shifts and determine how such findings may be employed to enhance refuse decomposition while maintaining healthy microbial populations. To do this, molecular techniques such as DNA and RNA fingerprinting, quantitative polymerase chain reaction (qPCR), and terminal restriction fragment length polymporphism (T-RFLP) were used.
Results showed that microbial population demographics varied both temporally and spatially. Primary factors affecting demographics were pH, moisture content of the refuse, refuse composition, spatial orientation upon placement, and population size of the methane-producing Archaea, a key group of microorganisms that dictate successful refuse decomposition. More specifically, it was found that a single species (Methanosarcina barkeri) was primarily responsible for initiating methane formation under stressed or low pH conditions, which are typical when fresh refuse is first placed in a landfill. It was also found that leachate pH was, in many cases, neutral while the rest of the refuse was under acidic conditions, indicating leachate pH is not a good indicator of overall microbial health in a landfill.
Bryan grew up on a dairy farm in Maryland and later his family moved to the mountains of North Carolina. He graduated from North Carolina State University in 1994 with a BS in Biological and Agricultural Engineering, got an MS from the University of Tennessee in 2000 in Biosystems Engineering, and completed his Ph.D. in Civil Engineering at North Carolina State in August 2009.
Bryan has over 12 years of engineering experience, having worked on agricultural, civil, environmental, wastewater and stormwater engineering. During that time he served as project manager, team leader and vice president at the firms he worked for. Bryan is currently the Vice President of Environmental Programs at the Environmental Research & Education Foundation. He is based in Raleigh, NC with his wife, Ann Margaret, and their two children.
Staley, B.F., de los Reyes, F.L. and M.A. Barlaz. Comparison of Bacteria and Archaea communities in mixed refuse, individual refuse components and leachate. (Microbial Ecology, to be submitted)
Barlaz, M.A., Staley, B.F. and F.L. de los Reyes. Anaerobic biodegradation of solid waste. In: Environmental Microbiology, Eds: R. Mitchell and J-D Gu. Wiley and Sons, New York (in press)
Staley, B.F. and M.A. Barlaz. (2009). Composition of municipal solid waste in the U.S. and implications for carbon sequestration and methane yield. J. Environ. Engineering 135:901-909.
Sadri A., Staley B.F., Barlaz M.A., Xu F. and G.R. Hater. Effect of an acidic and readily biodegradable non-hazardous process waste on refuse decomposition. (Waste Management, submitted)
Staley, B.F., Saikaly, P., de los Reyes, F.L. and M.A. Barlaz. Processing Heterogeneous Materials Prior to DNA Extraction is Essential for Minimizing Bias: A Comparison of Methods using Decomposed Refuse. (Applied Microbiology and Biotechnology, submitted)
Staley, B.F., F. Xu, S.J. Cowie, M.A. Barlaz and G.R. Hater. (2006). Release of trace organic compounds during the decomposition of municipal solid waste components. Environmental Science and Technology 40(19):5984-5991.