Technologies and Applications

Biogas

Biogas
© Fotolia/2744015

The production of biogas

Biogas can be extracted from the following sources:
• Organic waste from landfill sites (landfill gas),
• Municipal wastewater (sewage gas),
• Industrial, domestic or commercial organic waste,
• Agricultural waste materials and energy crops.

The process of fermenting the organic substance in the absence of air involves various anaerobic bacteria, the composition of which depends on the organic source materials and the specific processing conditions such as temperature and pH value. The microbiological processes that occur during fermentation are a decisive factor in the productivity of biogas plants.
In general, agricultural biogas plants use liquid manure and energy crops as a fermentation substrate. Using liquid manure for energy in biogas plants largely prevents the climate-damaging methane emissions from open liquid manure tanks.
To increase gas yields, more renewable sources such as maize, cereal crops and many other energy crops like sunflowers, Sudan grass, sugar beets, fodder radishes, sweet sorghum, etc. are being used. In addition, commercial plants also process wastewater and waste from food production, such as food particles and grease traps.
Apart from biogas, a digested sludge is formed, i.e. a mix of water, mineral components and undecomposed organic substances. This fermentation residue can be used in agriculture as a high-grade fertiliser, thus closing the nutrient cycle in the cultiva