Page 244 - Materials Chemistry, Second Edition

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Chapter 7

Sustainability of Agricultural

and Rural Waste Management

7.1 Introduction

Historically, energy supply was based on biomass and forest products.
Despite the shift to the conventional fossil fuel in many parts of the world,
the traditional fuel wood and charcoal still persist in many parts of the world,
especially in Asia and Africa where the majority still live in rural areas.
Today, fuel wood is of marginal importance to the industrialized world,
where fuel wood consumption is an insignificant percentage of the world
total energy. It is estimated that in the developing countries as a whole, wood
accounts for 21% of the total energy consumption; and in Africa as much as
58% (ABC Hansen, 2001). While using wood for fuel is becoming more com-
mon for various economic reasons the fact that replanting (afforestation) is
not occurring at a sufficient pace is invariably making fuelwood an increas-
ingly limited energy resource.
In many parts of the world, tons of agricultural wastes in the form of
straws, shells, stalks, husks, wood and forest residue, etc. are disposed of by
burning in fields. This is usually so mainly because other economical and effi-
cient uses have not been identified for the vast volume of residue produced.
However, burning of agricultural waste is increasingly being discouraged for
environmental, ecological, and health reasons. Agricultural wastes are recog-
nized as having “hidden” economic value. About 1.2 billion tons of oil equiva-
lent (approx. 15% of the world energy consumption) is assumed to be hidden in
unutilized biomass reserves including agricultural wastes (ABC Hansen, 2001).
Some of the uses found for plant residues include: mulch for soil cover;
compost for soil conditioner; fodder for animals; construction/building
materials, e.g. roofing in the rural areas, strengthening fiber/particle board
for panel doors and furniture, and insulating materials in walls and ceilings.
Other uses of agricultural residue include direct burning as fuel for
domestic and industrial cooking/heating and production of biogas and biomass

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