(203d) Bio Conversion of Glycerol to Methane and Hydrogen

Glycerol is produced as a by-product during the production of biodiesel. Until recently the quantity of biodiesel and subsequently glycerol has been minimal and the market has adsorbed the glycerol and the demand has historically remained high. With the recent increase in biodiesel predication capacity there has been a glut of glycerol production and the demand for glycerol has dropped. In fact, the glycerol produced from biomass is generally substandard and contains many impurities which must be removed to generate glycerol with any value. As a result of such issue the price for crude glycerol has dropped and many biodiesel producers are faced with either paying to dispose of their glycerol or providing it to energy generators at no cost. This has generated the need for alternative uses for crude glycerol.

A study was undertaken to determine if glycerol could be degraded using bacteria to produce methane. The methane from the degradation of the glycerol could then be used as a supplemental energy source. This study consisted of a the fabrication and operation of a pilot digesting unit. The system was seeded with domestic digester sludge and variables such as temperature and pH were adjusted to understand their effects on gas production rate.

Results indicate that both methane and hydrogen can be produced from the glycerol feed. A temperature of approximately 35oC appears to be optimal for gas production. A time lag is experienced prior to gas production but once initiated the system is easy to restart and maintain at a constant gas production rate. This paper will present the result of findings for this study.