Our Systems

Using the bio-slurry tank

• Collect 1,500kgs of cow dung and 1,500 litres of water or urine for the initial filling of the biogas unit. Then, mix the cow dung with the water or urine in a separate container beside the unit until it attains a porridge-like texture. After mixing, a the volume will be about 3,000 litres. Note that the amount of water or urine used depends on texture of the dung, therefore keep adding water or urine until the mixture is neither too thick nor too watery.
• Close the outlets of the digester and gas holder and then pour the mixture from the inlet on the side. There will be a discharge from the outlet on the opposite side once the digester is full to capacity. Then open the outlets for the air to exit from the gasholder completely. Close the outlets when the gasholder has descended.
• Leave the unit outdoors for 12 hours and the bacteria in the digester will start to work on the mixture. As it ferments, gas (methane) is produced and trapped in the gas holder. This will cause the gas holder to rise gradually until it covers 17 segments marked on the gas holder from the exterior. This should happen within 24hours or more, depending on the texture of the cow dung.
• Connect a burner or lamp from the outlet at the base of the digester to tap the gas, a blue flame will be emitted ready to be used for cooking and lighting on ignition. As you start using the gas, set more material to feed into the digester. Get 40 kg of dung and 40 litres of water and mix thoroughly and continue feeding as the gas begins to run out. Do not allow the mix simply to run out by fast feeding. Recommended feeding is 80-litre mixture for morning and evening.
• As feeding is effected, say, 80 litres, it will emit 60 litres of the used cow dung-water/urine mixture from the outlet on the opposite side of the digester as bio-slurry (effluent) is released. Each time the unit is fed, it is rejuvenated hence the continued buildup of gas. The bio-slurry is used as a fertiliser in the garden to boost crop production or to be used as a food supplement for chicken, fish and pigs.
• Note that feed material can be any organic decomposing matter like animal dung, plant residue and sewage. Other than cow dung, droppings from other animals like pigs, goats and chicken can be used. Also, agricultural and food waste include over-ripe or rotten fruit pulps, crushed peelings or vegetables, spoilt fruit juice and vegetables from processing factories, finely crushed non-edible and wild fruits, sugarcane juice, finely chopped sugar cane and molasses, rotten or waste grain, bran of wheat, rice and other cereal, spoilt potatoes, cassava, sorghum, maize, millet, powdered oil cake from edible and non-edible oil seeds like cotton, castor and jatropha.

Caution: With agricultural waste and food remains, it is a two-stage process. The first stage being fermentation, which takes place in a separate vessel, and then the second stage will be feeding of the fermented mass into the digester. This is done to allow the anaerobic bacteria digest the waste.