Environmental Science Clubs in Mwanga, Tanzania
Liana, 2014 (www.liana-ry.org)
5
Waste management
Objectives
1.
2.
Students are able to explain the concept of wastes and waste management
Students can be able to describe the problem of plastic wastes
- Types of plastic materials that litter the environment
3.
Students are able to explain the reasons why plastic wastes are dangerous to
the environment (harmful effects).
4.
Students are able to describe several methods of managing plastic waste and
identify methods that can be used to prevent the problem from getting worse.
Materials needed
-
Two films ‘The Majestic Plastic bag’ and ‘Plastic Takes over the Oceans’
Laminated pictures showing animals affected by plastics.
3 flipcharts (1. Scale of the problem, 2. Waste management hierarchy, 3. How to avoid
waste).
Teacher brings all kinds of plastic rubbish to the classroom: water bottle, a broken
flipflop (sandal), a broken shoe, bottle caps of different colours, pieces of a broken
bucket or basin, kinds of odd particles that are found in villages.
Leave to do task (no materials needed): Identify waste problems in your village (homes, shops
etc) and in your school. Educate the rest of the school on the issues identified. List the problems
in the exercise books.
Sequence of the lesson
1. Explain the learning objectives as above
Through question and answer method, teacher guiding students to understand meaning of the terms
 Wastes are substances or objects, which are disposed of or are intended to be disposed of or
are required to be disposed of by the provisions of national law.
 Waste management is the collection, transport, processing or disposal, managing and
monitoring of waste materials. The term usually relates to materials produced by human
activity, and the process is generally undertaken to reduce their effect on health, the
environment or aesthetics (=beauty of environment).
2. By using a flip chart (1), describe to students the problem of plastic wastes globally and
locally.
Use the large laminated pictures where appropriate.
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Environmental Science Clubs in Mwanga, Tanzania
Liana, 2014 (www.liana-ry.org)



In 2012, 280 million tonnes of plastic was produced globally. Less than half of it was consigned
to landfill or recycled. Of the remaining 150 million tonnes, some may still be in use; the rest
litters continents and oceans.
If current consumption rates continue, the planet will hold another 33 billion tonnes of plastic
by 2050. This would fill 2.75 billion waste collection lorries, which would wrap around the planet
roughly 800 times if placed end to end.
An estimated amount of more than 100.000 tonnes, mostly so-called micro-plastics, is floating in
the world’s oceans. This is a great concern in particular since plastic concentrated on the surface
of micro-plastics could enter the food chain.
Show the two films. First the Majestic plastic bag and then Plastic takes over the ocean.
3. Group work about harmful effect of plastics:
Divide students to groups and make them think of all harmful effects of plastics. Give 10 min time to
prepare their list. Ask one group to present. If something is missing from their list, other groups add
more.
Expected answers:
- A lot of plastic ends into Oceans creating huge areas of ‘plastic soup’ like the Pacific Trash vortex
and the other vorteces in the other oceans (show the laminated picture). The amount of floating
plastics in the world’s oceans is increasing dramatically. The Pacific Trash Vortex is a huge
floating island of marine litter in the North Pacific Ocean. The vortex is characterised by
exceptionally high concentrations of suspended plastics, such as plastic bags, bottles, containers
and other debris, that have been trapped by currents. It is now estimated to be the size of
France (two thirds of the size of Tanzania). Its impact on marine ecosystems is catastrophic due
to its toxic nature and threat to marine life.
-
-
Plastic debris can physically harm wildlife:
o They ingest particles, clothing and cleaning products containing plastics. Plastic bags are
quite commonly mistaken for food by animals, especially when the bags carry food
residues, are brightly coloured or are animated by the movement of water. A great
variety of animals, land and especially marine, can choke to death on bags, experiencing
much pain and distress. If swallowed whole, animals may not be able to digest real food
and will die a slow death from starvation or infection
o They get entangled in plastic objects (show picture). The worse are ropes, fishing nets,
any circle objects (loops)
o They die in big numbers due to this
Many plastics may be chemically harmful and toxic— either because they are themselves toxic
or because they absorb other pollutants.
Plastic littering beaches destroys nesting places of sea turtles on beaches. Some species go
extinct.
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Environmental Science Clubs in Mwanga, Tanzania
Liana, 2014 (www.liana-ry.org)
Talk about Tanzania at the end of group work
In Tanzania, both in urban and rural areas, the problem of plastic wastes has been increasing yearly.
It is now rare to walk in a street or beach without encountering some type of plastic waste. Most of
the plastics that litter our environment come from plastic shopping bags and plastic containers for
drinks. As things are now, there is no hope that the problem will decrease but increase dramatically;
this will affect each one of us so let us start acting now.
4. Waste management approaches ( flip chart 2):
The Waste Hierarchy can be a simple communication tool to remind us that:
- strategies which try to avoid products becoming waste are generally preferable to...
- strategies which seek to find a use for waste, which are in turn generally preferable to...
- strategies for disposal, which should be used as a last resort.
the most preferred option, avoidance and minimization
the least preferred option for managing waste, disposal
-
Ask students in their groups to think of how each rank is to be done. Use a plastic bottle as an
example.
Teacher goes through these categories of Waste disposal methods
Write on the blackboard the titles only. Emphasise the instructions in red.
Landfill
Disposal of waste in a landfill involves burying the waste. This remains a common practice in
most countries. A properly designed and well-managed landfill can be a hygienic and relatively
inexpensive method of disposing of waste materials. Older, poorly designed or poorly managed
landfills can create a number of adverse environmental impacts such as wind-blown litter,
attraction of vermin. Another common product of landfills is gas mostly composed of methane
and carbon dioxide, which is produced as organic waste and breaks down anaerobically. This gas
can create odor problems, kill surface vegetation and is a greenhouse gas.
Batteries, old engine oil, old medicines, electronics should not be dumped on a landfill
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Environmental Science Clubs in Mwanga, Tanzania
Liana, 2014 (www.liana-ry.org)
Incineration (burning in high temperature)
Incineration is a disposal method in which solid wastes are subjected to high temperature
combustion (burning) to convert them into residue and gaseous products. This method is useful
for disposal of residue of both solid waste management and solid residue from waste water
management. This process reduces the volumes of solid waste to 20 to 30 percent of the original
volume. Incinerators convert waste materials into heat, gas, steam and ash. Waste can be
converted to energy by high temperature burning. Slow burning of waste is very bad and
produces a lot of harmful fumes (typically practiced in Tanzanian towns and villages).
Incineration is carried out both on a small scale by individuals and on a large scale by industry. It
is used to dispose of solid, liquid and gaseous waste. It is recognized as a practical method of
disposing of certain hazardous waste materials (such as biological medical waste). Incineration is
a controversial method of waste disposal, due to issues such as emission of gaseous
pollutants.
Recycling
Recycling is a practice that refers to the collection and reuse of waste materials such as empty
beverage containers. The materials from which the items are made can be reprocessed into new
products. Material for recycling may be collected separately from general waste using dedicated
bins and collection vehicles. In some communities, people are required to separate the materials
into various different bins (e.g. for paper, plastics, metals). This is becoming the standard in
developing world. But poor people in the developing countries do it out of necessity.
Biological reprocessing
Recoverable materials that are organic in nature, such as plant material, food scraps, and paper
products, can be recovered through composting. The resulting organic material is then recycled
as mulch or compost for agricultural or landscaping purposes. In addition, waste gas from the
process (such as methane… biogas) can be captured and used for generating electricity and heat.
Don’t burn compostable rubbish such as leaves and small braches or flowers that drop
from the trees. Compost them(!), or leave them on the ground and thus you put them back
in the natural cycle of nutrients.
Flip chart 3.
What can an individual do to reduce the waste problem?
The most important method of waste management is the prevention of waste material
being created. Methods of avoidance include:
- Don’t buy things you don’t need
- reuse of second-hand products
- repairing broken items instead of throwing away and buying new
- designing products to be refillable or reusable (such as cotton and natural fibre
instead of plastic shopping bags, reusing a bottle rather than buy drinks in new
bottles)
- encouraging consumers to avoid using disposable products
- using natural fiber clothes rather than artificial fiber ones
- buying high quality products that last long rather than low quality cheap products
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