Livestock and poultry production are among the main economic activities in rural as well as urban areas of African countries.The livestock sector, in particular sheep, goats and camels, plays an important role in the national economy of African countries. In addition, the region has witnessed very rapid growth in the poultry sector.
However, livestock industry is contributing heavily to greenhouse gas emissions and waste management problems in Africa due to the absence of a sustainable Animal Waste Management System in the region. Most of the manure is collected in lagoons or left to decompose in the open which presents a severe environmental hazard.
The use of anaerobic digestion for animal waste disposal is an attractive way to address environmental problems, especially methane emissions. Anaerobic digestion of livestock manure is an alternative pathway for managing large organic waste loads and its associated problems encountered in large feeding lots and confined animal feeding operations.
Despite the numerous benefits associated with anaerobic digestion as a sustainable waste management strategy, these combined merits have never been quantified in African countries.The biogas potential of animal manure can be harnessed both at small- and community-scale. An essential aspect for adopting anaerobic digestion systems is the development of a methane market that acknowledges role of biogas systems in mitigating climate change.
With the present energy and pollution problem in Africa, conversion of animal manure as source of clean energy as well as organic fertilizer offers a great advantage. Anaerobic digestion technologies can help preserve and integrate livestock production within communities and create renewable energy resources to serve a growing bio-economy within rural communities.
Anaerobic digestion is a controlled biological treatment process that can substantially reduce the impact of livestock and poultry manures on air and water quality. An anaerobic digestion plant produces two outputs, biogas and digestate, both can be further processed or utilised to produce secondary outputs. Biogas can be used for producing electricity and heat, as a natural gas substitute and also a transportation fuel.
A biogas plant is a decentralized energy system, which can lead to self-sufficiency in heat and power needs, and at the same time reduces environmental pollution. The main features of a biogas facility are as follows:
- Processing of renewable energy source
- Reduction of malodors
- Removal of harmful pathogens
- Reduction of COD & BOD contents of processed waste
- Production of organic fertilizer for green areas
- Reduction in emissions of greenhouse gases
- Production of relatively clean water for flushing or irrigation
Animal manure-to-biogas transformation has enormous potential in reducing greenhouse gas emissions and harnessing the untapped renewable energy potential of animal manure. Biogas can be used as a fuel for internal combustion engines, to generate electricity from small gas turbines, burnt directly for cooking, for space and water heating. or for running vehicles.