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Chicken dung (dry or liquid) is not qualitative fertilizer itself. A long period of time is required (6-9 months) for chicken dung to become the bio-fertilizer. The longer chicken dung remains untreated the more nutrients are lost. Biogas technology allows production of natural bio fertilizer containing biologically active substances and microelements in a short period of time.
Chicken dung is perfect raw material for biogas plant as it gives high biogas yield.
During the design and construction of biogas all peculiarities of chicken dung are taken into consideration:
- humidity (dung is dry material)
- high content of protein, which is the source of nitrogen N;
- presence of bedding material.
Ideal humidity inside the digester is 89-93%. Chicken dung humidity is 60-75%. That is why chicken dung should be diluted. At the fist start of the digester fresh water from the external source is used. When biogas plant is put into full operation separated liquid from the digested biomass is used to dilute the fresh dung.
In order to level C:N ratio it is recommended to mix chicken dung with corn silage at 2:1 ratio (1 ton of corn silage to 2 tons of chicken dung). In case such mixture is used simple one stage anaerobic digestion technology can be applied. Besides investment reduction such mixture makes possible higher biogas and electricity yields due to the co-fermentation effect.
It is possible to use only chicken manure, but in that case 2 stage anaerobic digestion technology should be applied, which detaches hydrolysis and methenization stages of digestion. Such biogas plants proved to be very efficient but addition of another one reactor (hydrolysis) increases biogas plant price up to
When bedding material is present in the dung (straw or saw dust) standard loading bunker with disintegrators is used. Crashed bedding material is separated together with digested biomass. Bedding material and digested biomass are perfect fertilizer that improves soil quality.
Biogas yield from fresh manure is higher to be compared with manure containing bedding material. Egg laying chicken, poults and broiler fresh manure incase of cage system has almost the same biogas yield 130-140 m3 from one ton. Dung containing bedding is removed from the chicken hoses once in 35-40 days and can produce about 80 m3 of biogas from one ton.
Scheme: Poultry farms biogas plant
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Biogas plants
Poultry farms biogas plant
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