Table of content
Biogas is a mixture of CH4 (Methane), CO2 (Carbondioxide) and H2S (Hydrogen sulfide). Its proportion varies but could be described generell as + 60 - 70 % CH4 + 30 - 40 % CO2 + Traces of H2S
- mechanical breakdown outside the digester
- Hydrolytic bacteria
- Acid producers
- Methane Bacteria
The breakdown simplifies as follos: Complex Organics -> Higher Organic Acids -> H2 + Acetic Acid -> CH4
All nutrients goint into a digester are available in the effluents (expect for small amounts of sulfur releases as H2S and some N2 if the digester feed is unbalanced), thus providing a full spectrum of plant nutrients and reducing or eliminiating the need for chemical fertilizer input
Organic carbon compounds in the effluents increase the humic content of agricultural soil
When allowed to go toward completion, anaerobic digestion results in total destruction of most disease vectors which may have been present in the feed materials; nearly total destruction of most of those remaining; and very significant destruction of the most recalcitrant (including ascaris and other eggs). Also, the digestion process does not result in an new pathogen vectors.
With minor adjustment, biogas can be used in any way fossil gas is used
Pollutant emissions from combustion of biogas are similar to those from burning fossil gas,. When biogas is used to replace biomass or coal as cooking fuel, indoor air pollution and related health problems are greatly reduced
Volatile solids (what we smell) are largely consumed by digestion
Not attracted to digester effluents
Reduction of viability
Digesters, at near optimum mesophilic temperatures, with moderate solid levels (~8-12%) may be expeted to produce about 1 volume biogas per / 1 volume digester / day.