Laboratory-Scale Study on Hydrogen Production in a Fermentative Bioreactor Semi-Continuously Fed by Swine Manure

Jun Zhu, Associate Professor, Southern Research and Outreach Center, Waseca, MN
Curtis Miller, Assistant Scientist, Southern Research and Outreach Center, Waseca, MN

Funding Source

University of Minnesota Initiative for Renewable Energy and the Environment (IREE)

Objective

The objective of the project is to investigate the concept and possibility of producing biohydrogen through fermenting liquid swine manure.

Need or Impact

Producing energy from renewable resources is becoming more critical than ever to the economy of the United States. The outcome of this project provides valuable insight on the use of one of the most abundant bioresources for energy production, which is of great significance in reducing our reliance on fossil-based energy sources.

Project Status

The project is nearing completion. It was found that pH in the fermenter had a profound impact on the biological gas production process and needed to be monitored closely and adjusted accordingly. A reduction in pH could result in significant reduction in gas production. In this project, gas production was completely stalled when pH reached 4.0. To maintain a high rate of gas generation, the pH value in the fermenter liquid should be controlled above 5.0. The fermenter pH in this study was maintained between 5.0 and 5.7. Based on the analysis using gas chromatography, it was observed that the hydrogen production was very sensitive to process conditions and was easily interfered with or interrupted by methanegenesis, a process leading to methane generation, which could seriously reduce hydrogen productivity because, for one elemental carbon removed, there were four hydrogen ions consumed. It may thus be concluded that the major task in H2 production is to investigate effective methods to control methane productivity in the fermenter.