Dr. Ben Stuart, P.E.


Presentation Title

Biochemical Methane Potential of the Liquid Phase from Hydrothermal Carbonization of Municipal Solid Waste 

Dr. Ben J. Stuart, P.E., Senior Associate Dean, Old Dominion University - Batten College of Engineering and Technology


Hydrothermal carbonization (HTC) is observed as a scalable technique to convert wet biomass or organic waste (e.g. food waste and MSW) to carbon-rich solid fuels. Literature reports operating conditions of HTC ranging from 180-300°C based on different feedstocks which produces three main products; hydrochar green coal (75-80%), liquid phase with total organic carbon (TOC) (15-20%) and gases which is mainly CO2 (5%).  The liquid phase of HTC contains high loads of organics and inorganics and without recovery would be lost and still be considered a waste product which could increase the load at wastewater treatment facilities; also a loss of organic carbon, which could have been used for energy applications. In this study, the liquid phase from HTC of MSW was used as the feedstock for biological treatment to evaluate biodegradability and biogas yields.  A mixture of known composition (paper, plastic, metal, glass, food) representing waste that typically goes to the landfill has been created for testing under the proposed process. The purpose of this particular study was to 1) investigate carbonization experiments at varying temperatures (250, 280, 310 °C) and times (10 min, 1 h, 6 h) 2) evaluate liquid phase and biochar properties 3) preform AD bench scale bottle test on liquid phase to generate experimental data on biogas yields to understand biodegradability. Mass balance shows that 22-48% of carbon remained in the solid phase, 33-45% in the liquid phase and 15-44% in the gas phase. The condition of 280°C at 10 minutes yielded the highest TOC of 8.0 g/L with biogas yields of 222 g biogas/g TOC.   


Ben Stuart currently holds the positions of Senior Associate Dean of the Batten College of Engineering and Technology and Professor of Civil and Environmental Engineering at Old Dominion University in Norfolk, Virginia.  Dr. Stuart has been a PI/co-PI/co-I or Principal Scientist on over $26M worth of research projectsexternally funded by federal, state and industrial partners. His current research interests focus on biofuels/bioproducts production from waste and renewable feedstocks (specifically algal biomass) through the thermochemical processing of biomass.  His research in algal biofuels has led to three patents, as well as his participation as CTO in ECO2Capture, a start-up company focusing on developing and integrating enabling technologies in the algae cultivation and air pollution control markets.  He is the author or co-author of 50 refereed/reviewed publications, has presented over 90 papers or posters on his work, and has extensive consulting experience.  Dr. Stuart received his Ph.D. from the Department of Chemical and Biochemical Engineering at Rutgers, the State University of New Jersey, and he is a registered professional environmental engineer in the State of Ohio.