Agriculture Reference
In-Depth Information
Table 13.1
Summary of waste production and waste composition from some cities in sub-Saharan
Africa
Country/city
Waste production
(kg/hd/year)
Waste composition
(% organic)
References
Addis Ababa/Ethiopia
91.98
60
Couth and Trois (
2011
)
Arusha/Tanzania
531
65
Couth and Trois (
2011
)
Louga/Senegal
110-250
50
Collivignarelli et al. (
2007
)
Maputo/Mozambique
182
-
Hunger and Stretz (
2006
)
Nairobi/Kenya
260
-
Muniafa and Otiato (
2008
)
Uganda
200
71
Okot-okumu and Nyenje (
2011
)
Windhoek/Namibia
242
47
Couth and Trois (
2011
)
Yaounde/Cameroon
288
75
Ndoumbé et al. (
1995
); Parrot
et al. (
2009
)
(fertilizers, pesticides, and insecticides), which, when massively used are reported
to pose a serious threat to the environment, human and animal health.
Among the beneficial environmental impacts of UPA, we have the potential to
recycle organic waste within the cities, so the question is how that can be properly
done and how the cities can benefit from a suitable MSW management policy. Com-
bining organic/inorganic soil fertility management is specifically the recommended
approach in African Western or Eastern sandy or acidic soils by the African Net-
work for Tropical Soil Biology and Fertility Institute.
Cities in sub-Saharan Africa generate huge amount of waste ranging from 91
to 531 kg/hd/year, containing 50-75 % of organic waste (Table
13.1
); therefore,
if the produced organic waste could be composted, hundreds of tons of compost
could be produced daily and the policy of substituting the use of mineral fertilizers
by compost should be implemented. For an integrated and sustainable solid waste
management, any solid composting project should not just include technical aspects
but also various key elements of sustainability.
13.5
Composting
Composting is the biological process of converting organic substrate, in the present
of oxygen, into CO
2
, H
2
O, heat, new cell generation and humus. The end product
of the composting process is compost, a product that is high in nutrients, rich in
humic acids, and contains a diverse community of microorganisms. Compost can
be utilized as organic fertilizer or soil additive, compost land application completes
a circle in which nutrients and organic matter which have been removed by harvest-
ing of different agricultural products are replaced (Nwaga et al.
2010
). Centralized
composting processes for MSW primarily fall into two categories: windrow com-
posting and in-vessel composting, windrow composting being the most suitable for
large quantities of diverse biodegradable waste (Last
2006
).
