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William T. Stringfellow, Ph.D., is Director of the Ecological Engineering Research Program at the University of the Pacific in Stockton, CA. He also has a joint appointment with the Berkeley National Laboratory in Berkeley, CA.
He received his B. S. in Environmental Health from the University of Georgia (Athens, GA) in 1980 and his Master’s Degree in Microbial Physiology and Aquatic Ecology from Virginia Tech (Blacksburg, VA) in 1984. He received his Ph.D. in Environmental Sciences and Engineering from the University of North Carolina at Chapel Hill in 1994 and worked as a Post-Doctoral Fellow in the Civil and Environmental Engineering Department at the University of California at Berkeley.
Dr. Stringfellow is the first author on over 25 journal publications, has been the lead author on over 40 government reports, and has made hundreds of presentations on the subjects of water quality, water treatment, and the microbiology of engineered systems. He has over 20 years research and consulting experience in both the US and Europe. Dr. Stringfellow’s research interests include the assessment of NPS discharge impacts on surface waters and the use of wetland systems to mitigate NPS impacts on the environment.
Dr Stringfellow was the Chief Scientist for the San Joaquin River Dissolved Oxygen TMDL Project, an ecosystem level assessment of non-point source (NPS) impacts on water quality in the San Joaquin River in California’s Central Valley.
Visiting Professor, Environmental Microbiology, University of California, Berkeley, Fall 2007
Adjunct Professor, Hydrologic Analysis and Design, University of the Pacific, Fall 2006
Adjunct Professor, Introduction to Environmental Engineering, School of Engineering & Computer Science, University of the Pacific, Spring 2006
Lecturer, Water Resources, Department of Civil & Environmental Engineering, University of California Berkeley, Fall 2005
Lecturer, Microbiology for Engineers, Department of Civil & Environmental Engineering, University of California Berkeley, Spring 2003 and 2004
Graduate Research Advisor, Department of Civil & Environmental Engineering, University of California Berkeley, 1999 to present
Undergraduate Research Advisor, Environmental Sciences Program, University of California Berkeley, 1997 to present
Undergraduate Research Advisor, Center for Science & Engineering Education, US Department of Energy, 1998 to present
Outstanding Mentor Award, Lawrence Berkeley National Laboratory, 2001
Outstanding Mentor Award, Department of Energy, 2002
The major focus of my research is the study of environmental biokinetics. Microbial activity in both natural and engineered systems is dominated by the balance between growth and decay (cell death). In an open system, the state of the microbial community is determined by the physical and chemical conditions of the environment and is rarely, if ever, limited by availability of microorganisms. The microorganism will grow until the limiting condition is met, whether it is nutrient availability, energy supply, toxicity, or physical parameters such as available surface for attachment or washout conditions.
In engineered systems, the parameters controlling microbial activity can typically be manipulated. The condition of the system is a balance between the inputs and the standing microbial biomass in the system. This balance determines the output from the system. For example, in wastewater treatment, the system is typically maintained in a carbon-limited condition (low carbon-mass to biomass ratio) so that the output (effluent) is carbon free. How the system balances over time and responds to changing conditions is a function of the kinetic relationship between the microbial biomass, the system environment, and the growth limiting condition. Experimental techniques and modeling are used to determine fundamental kinetic properties of microorganisms and relate those properties to engineering operations with the purpose of achieving specific environmental objectives.
My current research is focused on biokinetic issues related to achieving water quality management objectives, with a regional focus on the San Joaquin River Basin in the California Central Valley. Water discharged from non-point sources, particularly agricultural areas and wetlands, are being regulated for the first time under a variety of programs, including basin wide management plans referred to as total maximum daily load (TMDL) programs. On-going fundamental and applied studies examine algal growth in the San Joaquin River and tributaries; the biological production of organic carbon in wetlands and agricultural drains; and the environmental fate of pesticides in agricultural ponds and managed wetlands.