how does biogas come from rotting waste matter ?
How does biogas come from rotting waste matter ? Contaminated and carbon dioxide diluted methane, or biogas arises as a byproduct of doing something as green as composting organic waste. Methane is one of the most destructive greenhouse gases and could be contributing to global warming. However, if it is harvested, the energy equation is turned on its head. This is done by ensuring it does not escape from degenerating organic matter, and hence, necessitates its containment in an airtight vessel. The sealed containment therefore has the double function of inducing anaerobic conditions and trapping the resultant methane.
imagine if this was the sequence of motor fuel production
How is Biogas a product of anaerobic composting ?
It is interesting to take a closer look at the chemical processes which lead to methane production or methanogenesis.
During the anaerobic digestion process, complex molecules are broken down in various stages to produce smaller simpler molecules, and the end product of breakdown is carbon dioxide and methane, two potent green house gases (with methane about 10 times some sources (Wikipedia) say 20 times more so).
warmer and cooler processesIn the context of garden composting, many people on the more ‘popular’ end of the spectrum of authorship describe anaerobic composting as ‘cold’ but in fact in its commercial application, it is possible to control conditions enough to differentiate between a cold and a hot version of anaerobic composting (digestion), in which different bacteria proliferate. Thermophilic digestion occurs at 39-47 degrees and mesophilic at 30-38 degrees centigrade. There are more diverse species involved in the mesophilic digestion, but fewer pathogens are removed because mesophilic digestion is that much cooler.
recycle waste : even organic lignin residue can be used Whether the starting substance is a sugar, a fat or protein, all the molecules get shorter and smaller during anaerobic digestion and all end up as either methane or carbon dioxide, except for a few biogas contaminants and Lignin.
Most of the bacteria involved in anaerobic decomposition are not able to break down Lignin, which remains as a residue. Lignin strengthens cell walls and the wood in trees. It is a biopolymer and is water repellent as opposed to the polysaccarides (complex sugars like cellulose) found in the cell wall. Its resistance to water absorption allows vascular tissue in trees to transfer water through the tree efficiently (Wikipedia).
The lignin residue can be used as dressing to add organic matter to soil, thus producing an organic fertilizer.
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