Biogas from Chicken Manure

[Henlus]

Can you say more about the C/N ratio?

You need to adjust the ratio to fall within 25-30. Eg, if you have chicken droppings (c/n = 10) and cow dropping (c/n = 20). To combine them to get a mixture that is c/n = 25, use the formula below: R1 x Q1+R2 x Q2 = (Q1+Q2)xR.
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Where R1 and R2 = c/n ratio broiler and cow droppings respectively and Q1 and Q2 = weight of broiler and cow droppings respectively. R is the desired c/n ratio which is 25.
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We know that R1=10, R2=20, R=25. Let's take Q1=1kg.
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(1kg x 10) + (Q2 x 20) = (1 + Q2) x 25
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10 + 20 x Q2 = 25 + (25 x Q2)
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Q2 = 3kg.
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Therefore for every 1kg of broiler dropping you need 3kg of cow dung.
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It is important to note that c/n ratio can vary from one pen to the other. So the values used here can differ from that of your own animals.
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C/n ratio is usually lower if the manure contains urine. If you use litter materia like sawdust, straw etc in your animal pen, the c/n ratio will be higher. The best way to determine c/n ratio is through lab testing, but you can still run your digester by using estimated values from literatures.