The diagram below illustrates Bio-gas digester which Express Drainage Solutions Kenya Ltd can design, supply and install;


Why Express Drainage Solutions Kenya Ltd Bio-gas Digester?

Our on-farm biogas plants collect cow dung from adapted cattle sheds, mix it with water and channel it into fermentation pits or Biogas digester tanks. The resulting gas is fed directly to the farmer’s household or to institutions to provide energy for cooking, laundry and lighting. The biogas plants also produce organic waste which is dried and used as fertiliser. Both fertiliser and fuel wood are increasingly expensive in Kenya and biogas has a potentially important role to play now and in future.

What is a bio-gas digester and how does it work?

The picture below illustrates Express Drainage Solutions Kenya Ltd typical biodigester after full construction;


  • Cow dung bio-gas digesters collect animal waste (feces and urine) in an underground tank. Catalysts break down the waste within the tank by digestion, which releases a mix of gases, mostly methane. The gas rises and collects in a domed ceiling where it builds pressure. A valve and a hose attached it to the top of the tank, allowing it to be piped directly into the house where it is connected to a gas-burning stove or to other utilities. The gas does not smell (like many might suspect) and does not make smoke.
  • When the tank reaches capacity, excess effluent that has already undergone digestion (“slurry”) is pushed out of the tank by natural pressure, through an overflow pipe and into a holding bin (displacement tank), where organic waste like leaves, grass or rice husks can be added to create high-quality fertilizer and mulch.

The advantages of biogas are manifold. Biogas by itself can positively affect the economy of rural areas. The principal benefits of biogas include:

  •  Conversion of natural organic waste into fertilizer: The conversion is carried out in a machine called  bio gas digester. Cow dung slurry is put into the machine. The product is organic fertilizer of high quality. The fertilizer obtained is rich in nitrogen. It has been analyzed, that, fertilizer made by the bio gas digester contains nitrogen content 3 times more than the product made by conventional processes. It is completely natural and free from harmful synthetic chemicals.
  • Eco friendly energy production: The calorific value of biogas is equal to that of half liter of diesel oil (6 kWh/m3). Methane is a key component of the gas. Biogas is fully capable of replacing other rural energy sources like wood, hard coal, kerosene, plant residues, and propane. Hard coal possesses a calorific value of 8.5kWh/kg per 0.7 kilograms. Larger biogas plants generate and feed electricity into mainstream power grids. Smaller biogas production units can support lighting and cooking requirements
  • Considerable workload reduction in rural areas: This is particularly true for rural women engaged in day to day household work. Installing a biogas unit will relieve her of the tiring and tedious job of collecting and ferrying firewood. Since, biogas burns cleanly, the rural homes will not suffer from smoke and consequently rural denizens will suffer less from physical problems like bronchial complications. Cooking is also easier with a gas stove and takes less time.
  • Visible improvement in rural hygiene: Biogas contributes positively to rural health conditions. Biogas plants lower the incidence of respiratory diseases. Diseases like asthma, lung problems, and eye infections have considerably decreased in the same area when compared to the pre-biogas plant times. Biogas plants also kill pathogens like cholera, dysentery, typhoid, and paratyphoid.
  • Environmental benefits on a global scale: Biogas plants significantly lower the greenhouse effects on the earth’s atmosphere. The plants lower methane emissions by entrapping the harmful gas and using it as fuel.
  • Protects the earth’s natural resources: 1 biogas plant is computed to save 32 liters of kerosene and 4 tons of firewood every year. The organic chemical plant also contributes indirectly to the protection of soil.

Garden Chambers, 2nd Flr. Off Jeevangee Gardens, Mokhtar daddah Street

+254 727 160738

+254 738 627632

P.O.BOX 8620-00200, Nairobi, Kenya