WASTE DISPOSAL
Waste can be
defined as unwanted materials or substances that are left after you have
used something.
Waste materials or substances are unwanted because the good part
of them has been
removed or it is not used.
TYPES OF
WASTE
According to
physical state, wastes can be classified as;
Solid wastes
Sludge wastes
Liquid wastes
Gaseous wastes
Solid wastes
These are
wastes which comprise of about 73% of the solid wastes. Example of solid
wastes include
house hold solid wastes such as vegetable, fruit and garden wastes,
papers, cans,
plastics, bread wrappers, broken glassware, batteries from watches,
radios, mobile
phones, etc. and junked automobiles.
Industrial
solid wastes
These types of
wastes include packaging materials, metal turnings, scrappers, plastics
and junked
automobiles.
Medical
solid wastes
These include packaging, used syringes and soiled dressings.
Market, yard
and street sweepings
These are wastes
such as paper, glass, cans, plastics, and vegetable wastes.
Sludge
wastes
These are
semi-solid wastes i.e. wastes which are neither solids nor liquids, for
example,
a mixture of
livestock urine and cow dung.
Liquid
wastes
These are wastes
which are in the form of liquid or watery materials. They contain less
than 25% solid
substances. Example of liquid wastes include water from sinks, wash
basins and baths,
urine, industrial effluent, oil spills and agricultural chemicals e.g.
insecticides and
pesticides.
Gaseous
wastes
These are waste
materials which are released into the atmosphere in gaseous state.
Examples of
gaseous wastes are carbon dioxide, carbon monoxide, sulphur dioxide and
nitrogen dioxide.
Most of the
gaseous wastes come from industries and automobile exhaust fumes,
laboratories and burning
of organic materials such as plastics and polythene bags.
Wastes can
also be classified as
Hazardous waste
Non- hazardous
wastes
Hazardous wastes
These are wastes which are not harmful in that they do not endanger the health of living organisms. Examples of such wastes include packing materials, papers, plastics, cans, water from wash basins, baths, etc, vegetable, fruit and garden wastes and glass.
Furthermore, wastes can also be classified as;
Recycled wastes
Non- recycled
wastes
Recycled wastes
These are wastes which can be used to manufacture new products. The used
materials
are recycled
instead of being thrown away. Examples of waste materials which can be
recycled include
metals, glass, papers, cow dung, beer bottles and plastic bags.
Non- recycled wastes
These are
wastes which cannot be used to manufacture new products and cannot be
used again e.g.
soiled papers and cotton wool.
Exercise 3
Visit dumping
sites and industrial areas. List and classify the various types of wastes observed
By their physical
states
As hazardous and
non- hazardous wastes
As recycled and
non-recycled wastes.
WASTE DISPOSAL
Waste
disposal is the process of getting rid of waste materials that people generate
or
the act of
getting rid of unwanted materials and items of no value or in excess.
Reducing the amount of waste we produce. For example we do not have to buy plastic bags each time we go shopping. We carry a woven basket instead.
Re-using items instead of throwing them away. For instance we
can use an empty margarine container to store sugar.
Recycling waste material. Some wastes can be changed to other
products. For example broken glass can be melted and used to make new glass bottles.
PROPER WAYS OF DISPOSING WASTE
Most cities and
towns have waste collecting departments or private firms that gather municipal solid wastes from homes and other buildings.
Incineration
This is the method which involves burning of waste products at high
temperatures.
Land disposal
This involves
hauling garbage to an area owned by a community or a private firm. Land disposal may range from unsanitary open dumps to sanitary landfills.
Unsanitary open
dumps are
poor methods of waste disposal because they cause environmental problems such as:
May produce bad
odors
Ruin the area’s
appearance
Rain water drains
through refuse and carry harmful substances to nearby streams and to water used for drinking.
Decomposing
wastes produce flammable gas called methane and methane explosions may result.
Sanitary land
fills are
intended to protect the environment. The waste is packed firmly
by tractors and
covered with specially manufactured materials. The covering is done in
order to limit
blowing papers, odors, fires and run off of polluted water.
Note: A secure
sanitary land fill is lined with materials that prevent water from carrying
leachates
(dissolved substances) from the refuse into underground water supplies.
Waste bin collection
This is intended to
collect smaller quantities of wastes. The waste bins are placed along
the corridors or
in every room or house which in turn is emptied into big waste bins.
Sewage system
Sewage is water
that contains waste matter produced by human beings. It is also called waste water. Sewage comes from toilets and sinks of homes, restaurants,
office buildings and factories Sewage system involves the use
of collection pipes or pit latrines where the sewage is
periodically removed and transported to a sewage works where it is treated to make it harmless.
Recycling
Recycling is the
process of reusing the materials instead of throwing them away. The
waste products
are used to manufacture the same or different products such as:
Cardboard or cow
dung can be used to generate Biogas.
Thermoplastics
can be melted and remoulded.
Organic wastes
produced domestically or commercially can be composted.
Kitchen refuse
can be used to feed animals such as dogs, pigs, cattle, etc.
Newspapers,
magazines cartons and packing materials can be used to manufacture
tissue papers.
In Tanzania
coffee husks are converted into a form of charcoal which is used for
cooking
Coconut and
agricultural wastes can be converted into papers.
Jute wastes can
be converted into hard boards.
Sewage and
factory wastes can be purified to an extent that can be pumped into
storage tanks and
used for all domestic purposes.
Glass bottles can
be used for storing specimens or medicines.
Waste generation reduction
Waste reduction
is deliberate effort to produce fewer wastes. For example, people can
reduce waste by
buying items that can last longer or have less packing.
Produce bad odors
Ruin the areas appearance
Decomposing wastes produce flammable gas called methane and this may result to
explosion of the gas which may cause a loss of material property and human life.
Rain water drains through refuse and carry harmful substances to nearby streams and
water used for drinking which may later lead to eruption of diseases like cholera and
may kill organisms found in water
Poor disposal of clinical wastes on land fill site may encourage bacterial breeding leading to possible infections in the area
Unregulated dumps where waste is burned in the open can cause smoke and foul smelling air.
Burning may also result into production of air pollutants which may affect the ozone layer and possible cause of respiratory diseases.
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