Image: Gusto Images/Science Photo Library
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Agricultural,
industrial and urban developments are
considered to be fundamental components of
social and economic development but are,
however, accompanied by pollution generation.
To mitigate this problem, there is a need to
integrate waste treatment into development
initiatives. For developing economies
such as those in eastern Africa, it is equally important to integrate
pollution mitigation, production of
value-added products and renewable energy to
support sustainable management of industrial
waste.
The
need for effective systems for waste
management is of utmost importance in eastern Africa
where processing of agricultural products
generate enormous amounts of waste. Huge
quantities of organic residues are generated
by agro-industries such as sisal decortication
plants. Common disposal methods of
agro-residues and waste include burning and
dumping on site, dumping in unplanned and
uncontrolled landfills, and discharging in
nearby water bodies. All these approaches pose
an environmental risk/hazard. In addition to
the agro-industries, slaughterhouses and food and
fish processing factories in
eastern Africa
are adding to the large amounts of wastes and
wastewater that are disposed off untreated
into the environment.
The
problem is intense in major urban centres on
the shores of
Lake Victoria where over 40 fish processing factories are
discharging large quantities of untreated fish
processing waste and wastewater into the lake.
Fish processing wastewater is known to
have high 'biochemical oxygen demand' (BOD), solids,
proteins, fat and oils together with inorganic
compounds from detergents and disinfectants
used in the factories.
Apart
from the problems caused by waste/wastewater,
eastern Africa
is faced with a problem of over dependency on
imported oil because none of the member
countries has exploitable oil reserves.
The region therefore needs to seek to
develop alternative ways to support growth and
development by use of renewable energy
sources. The vast amounts of waste from
breweries, textile mills, municipalities, food
processing and agro-industries can be a source
of energy in the form of biogas. Biogas
technology on the other hand is still at its
infancy and therefore, installations of plants
to generate biogas using agricultural residues
by means of microbial biotechnology, is very
important to support sustainable technology
development.
There
has also been consideration for large scale
production of biogas as a source of
electricity in eastern African countries.
Preliminary case studies at agro-processing
factories indicated that utilization of
organic waste for biogas/electricity
production at the factory plants is feasible
and could be an energy alternative to the petroleum fuels
being used by these factories. For
example, the utilization of sisal and
sugarcane residues alone for biogas production
in
Kenya
and Tanzania, can substitute fossil fuel by an annual
equivalent of 91,300 and 67 400 tons of diesel
oil, respectively. This give clear environmental and
economic incentives to the factories
generating the wastes. Bio-energy
is clean because it is produced from waste
materials, it is renewable and hence
sustainable. The
surplus biomass and wastes as raw materials
could also be used to produce other
value-added products such as organic chemicals
and fertilizers, providing a sustainable means
for reducing environmental load.
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