Ideal raw material for biogas
Cattle manure is the ideal raw material for biogas. Unlike other raw materials, cow dung has everything bacteria needs to build the bacterial cell with nothing to add. Moreover, cattle manure already contains bacteria.
A manure biogas plant has the simplest design. But, as in the case of other substrates, the designer and constructor must pay careful attention to substrate characteristics.
Animal keeping and manure removal
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Pure natural manure
The ideal for biogas production is pure manure without bedding or water. Such manure occurs when the cows are kept on rubber mats or paved floor and manure is removed mechanically.
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Manure with straw or sawdust bedding
Animals are kept on bedding, and the manure is removed mechanically. Such manure with bedding should be passed through an additional equipment-shredder. Or the straw should be shredded before it is mixed with the manure.
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Manure flushed with water
Manure is removed mechanically, flushed with water, and transported by pipe. The disadvantage of this method is the dilution of manure with water, and as a consequence, a volume increase for the biogas reactors and the consumption of heat to warm the slurry in the winter.
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Manure with sand bedding
Biogas conversion of such manure is possible, but it is necessary to install additional hydrocyclones to remove sand from the reactor.
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Dry manure with soil impurities
Another way to keep cattle is on compacted soil. It is important here for the driver to not capture soil when collecting the manure.
Of all the methods for keeping animals the first is the best for biogas. For the rest, biogas processing is also possible though slightly more expensive.
Examples of biogas plants from our practice: manure with water flush (Ukrainian Dairy Company), manure with sand and stones (Karasu, Kazakhstan), and pure manure (Chichedagi, Turkey).