2.6   Livestock Keepers Group in Karatu 
“(Kikundi cha Wafugaji Karatu – KIWAKA)”  

2.6.1    Introduction  

One member of the group participated in the exhibition. The tubular plastic biodigester was demonstrated (Plate 14). The digester is a low cost family size biogas system which use plastic sleeves to meet the real economic concerns of rural farmers. It substitutes the use of fuelwood and reduces pressure on forests.  



Plate 14.  Exhibitor demonstrating the tubular plastic biodigester


Due to their suitable carbon to nitrogen ratio(C:N) and total solid content, cattle, pig and poultry manure is highly recommended as raw materials for biogas production. Two cattle or eight pigs are enough to produce dung for a 5m3 bio-digester, which produce enough gas for a family of six people.  The digester provides gas at a rate of 0.354 M3 per day sufficient to cook meals for about 3 hours (Fig. 3).


Fig. 3  Low cost plastic Biodigester        O-GAS                                                 In order to maintain continuous production of biogas, six stages  are involved. (Fig. 4)  
 are involved. (Fig. 4)



2.6.2    Biogas production and utilization

Biogas technology has several advantages under agroforestry systems (agrosilvopastoral and silvopastoral systems) and in protecting the environment.  The major advantages are;  

(a)    It provides alternative to fuelwood and thus reducing the rate of deforestation

(b)   Improves women welfare by reducing workload of collecting fuelwood

(c)    Improves crop-tree livestock farming system through nutrient recycling.

(d)   Improves the health of women and children (otherwise exposed to harmful smoke and fumes from traditional fuels) and provides non-polluting and smokeless kitchen.

(e)    It is a relatively cheap source of energy compared to other fuel.

(f)     It promotes health by the safe treatment of manure-particularly human wastes to prevent the spread of diseases.

As a renewable energy it provides reliable power supply and is an environmentally friendly technology.



2.6.3        Benefits and cost comparison


Bio-gas offers ernomous economic, social and ecological advantages and has an important role to play in providing sustainable energy production Lekule(1996), reported that, after adoption of biogas digesters in Tanzania, woodfuel consumption decreased by 60%.


Comparing with other energy sources i.e. charcoal and kerosene, a survey conducted in Tanzania showed that 3 bags of charcoal and 121 litres of kerosene were consumed per month in a family of six. If converted to money, it is approximately U$ 8 for charcoal and U $ 49 for kerosene which presents a real saving when biogas is used.

Construction cost of tubular plastic sleeve bio-digester is less than US $ 100 as compared to US $ 1000, when constructing large-scale conventional bio-gas plants (Table 1).



Table 1: Estimated costs of materials for a family size tubular plastic bio-digester based on the installation cost of bio-digesters in Tanzania




Polythene sheet(0.2)mm thick)

18 kg


Gas pipe (21 mm)id)



PVC"T" and "L" pieces



Steel pipe



A tap (to control gas flow)



PVC for inlet and outlet



PVC, (10mm id)



Inner tube strips



Plastic bottle






SOURCES: Lekule (1996)




For more information please contact;-

Mr. Emmanuel Silloh,

Kikundi cha wafugaji Karatu (KIWAKA),

P. O.  Box 92, KARATU - ARUSHA.



The Management East African Crossborder Biodiversity Project acknowledges the East African Co-operation secretariat for the invitation to support the Exhibition by Jua Kali/Nguvu Kazi during the signing of the East African Cooperation Treaty.

We are grateful to the  commitment and contribution from;


(a)    The Tanzania Association of Foresters (TAF) especially Mr. Jacob Mushi, Executive Secretary for the overall coordination and guidance to other participants


(b)   Mr. J. Massao and family Tree Nursery


(c)    KAKUTE Limited


(d)   TEMDO, Arusha


(e)    Njiro Wildlife Research Centre


(f)     “KIWAKA”




(h)    UNDP-GEF East African Crossborder Biodiversity Staff, Arusha


Special thanks are due to Mr. & Mrs. J. Massao of “Matumizi endelevu ya misitu ya asili Iringa”. (Sustainable utilization of natural resources and biodiversity conservation) Iringa for their support into compilation of these proceedings.

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