Abstract
Coffee processing done by wet and dry methods discard away alot of the biomass generated by
the coffee plants at different stages from harvesting to consumption. This includes cherry wastes,
coffee parchment husks, sliver skin, coffee spent grounds, coffee leaves, and wastewater. Wet
processing uses up to 15 m3of water to produce one ton of clean beans and for every ton of beans
produced, about one ton of husks are generated. It is estimated that coffee processing is
generating about 9 million m3 of wastewater, and 50,000 tons of husks annually in the
Kenya.(George Tchobanoglous, et al).
Energy from coffee waste is in form of biogas that is used as an alternative energy on the wet
method process for extraction of coffee beans from coffee cherries. During the wet method
process enormous amounts of waste water is generated in the form of pulp and residual water.
This waste water is high in organic matter and acidity content and with a Chemical Oxygen
Demand value that varies between 18000 and 30000 milligrams per litre. The waste water is used
to produce biogas as an alternative energy.(Antier, P., A)
Kenya is a major producer of coffee in East Africa. Among the areas where coffee farming and
production is done is at Karatina town in Nyeri County. This research was carried out with
Gatomboya wet coffee mill in Karatina as the focus of the case study.
The main aim of this project research was to get the biogas potential of coffee wastewater
through COD and BOD tests and the BOD/COD ratio used to determine that.
A lack of a bio digester at Gatomboya wet coffee mill and lack of necessary resources however
made it impossible to get the actual amount of biogas that can be produced from say 1m3 of
wastewater. This was the major limitations of this project.