Biodigester Construction: How To Make a Biodigester
A Biodigester refers to a waste management technology allows the decomposition of organic materials mainly manure, human or animal waste to produce water and methane gas (biogas). A biodigester is normally made out of concrete, HDPE Tanks or any other material that incubates anaerobic/aerobic fermentation of organic materials. It has an inlet for organic material (human waste/manure) and an outlet for expelling decomposed material (effluent/Water).
Bio digesters have three parts — the body (bio digester tank), the inlet and the outlet baffles. The baffles regulate the fluids in each part. Other parts of the system includes a grease traps (to trap any fat/oil from the kitchen) a french drain and a soak way pit
The process including digging a ditch of at least 4 feet deep and but length and with depend on the bio digester capacity. Construction of a biodigester tank is then done on this 4 feets deep hole.
Again a 4-cubic-metre (at least) ditch is requires to be filled with hardcore and act as filtration area for excess water from the biodigester. This area can also be fitted with water purifier and water reservoir for water if water recycling is required. Most biodigesters do ‘soaking’ where a ditch is dug and filled with rocks to drain all waste households.
Biodigester tanks are designed to be incubators to bacteria. They provide all the conditions necessary for aerobic and anaerobic decomposition of organic waste. The key process that occurs in a biodigester is called anaerobic digestion. This is a natural process in which micro-organisms break down (eat) organic materials in the absence of oxygen.
The inside chamber is devoid of oxygen, which encourages growth and multiplication of bacteria responsible for digesting the waste. To accelerate the multiplication of these bacteria, artificial bacteria enzymes are added to the waste.
A Biodigester simply means a tank which digests organic material biologically. It is a tank which digests, anaerobically (without air) organic material and produces methane gas (biogas), for cooking, lighting and heating cabondioxide and water
However, for a Biodigester to produce enough methane/ Biogas to make it practical for cooking alone, it would require a lot of household waste and toilet waste plus more manure from farm animals. It can be used as biogas, but only if it is available in large quantities.
Bio digester tanks apply to the displacement principle, which dictates that when waste water is flushed out of the tank, an equal amount of water from the tank to the soakage pit is replaced.
How much does a Biodigester cost
On average it cost Sh75, 000 to install a one-cubic-metre and Sh120, 000 to install a two-cubic-metre one. Prices increase based on the number of users/capacity in terms of cubic metres.