Biogas potential from biodiesel production residues

Biogas production is developing rapidly all over the world. In some countries as Germany and Sweden, its supply after purification in natural gas networks has already started. Biogas production is one of the most promising and environmentally friendly alternative energy technologies, so its development will continue. Also in Latvia, the profitability of biogas production will continue to increase, especially from the point of view of environmental protection. Biogas is now more advantageously used for cleaning and feeding into gas networks for electricity and heat production, but in the future it could also be used as a fuel in city buses, as it is already done today in Linköping and Stockholm. This would further reduce GHG emissions. It is also important to use various organic residues from different productions. In order to find out what is the potential of biogas from the raw materials of production residues of the biodiesel production plant, a study was conducted using laboratory equipment. In 16 bioreactors, filled with raw materials taken from the residues of the biodiesel production, anaerobic fermentation took place at 38 °C. After 30 days fermentation produced 0.888 L·gE−1DOM of biogas (0.497 L·gE−1DOM of methane) from rapeseed meal, and 1.371 L·gE−1DOM of biogas (0.814 L·gE−1DOM of methane) from rapeseed oil refining by-product, as well as 0.765 L·gE−1DOM of biogas (0.414 L·gE−1DOM methane) from the glycerol distillation residue. 1.265 L·gE−1DOM biogas (0.252 L·gE−1DOM methane) was obtained from biodiesel production wastewater. The study shows that it is possible to obtain an unusually high amount of methane per unit of dry organic matter from biodiesel production residues, but with a high content of hydrogen sulfide from rapeseed meal and glycerin distillation residues. The use of these residues in the production of biogas could be very useful.