Water
Purification using Ozone
When choosing their science project, Emma
Grotto and Sophie Kirkman could not decide whether to do ozone water
purification or making biodiesel from used vegetable oil. They researched both
topics and eventually chose the water purification project because it seemed
more relevant and necessary in Africa.
How it worked
1. A series of transformers stepped up
the voltage to about 20 000V.
2. They cut a glass tube from a
fluorescent light to 20cm long, and lined it with Aluminium net.
3. They put an aluminium rod in the middle,
lined it with aluminium net, and held it in place with silicone rubber.
As a result of the high voltage, electrons are
stripped out of the oxygen molecules in the air between the gap resulting in a
purple discharge, and the formation of ozone gas.
A small fish tank pump was used to
pump air through the sealed tube, and the ozone rich air leaves the other side
of the glass tube through a silicon pipe and is bubbled through the water to
purify it. Ozone is a highly oxidising gas which will deactivate viruses, kill
bacteria, destroy organic matter and precipitate inorganic compounds hence
purifying the water.
Aquaponics
Abigail and Eden Putterill were inspired to do
this topic when they visited their uncle who used a similar set up.
Benefits of aquaponics
-Two products are produced by the
system: fish and food from the plants.
-There is no soil borne diseases.
-There is no extra labour required
to till.
-The plants remain hydrated and
will not have the problem of wilting.
-The system uses 60-70% less
energy than agriculture.
-The plants are healthier and
there are increased growth rates
-Lettuce can be grown in 3 weeks
instead of 3 months.
-This system does not depend on
seasons.
-It is very cost efficient once it
is set up because a large profit can be earned.
Fish in an aquarium produce waste.
This waste (containing ammonia) can be used to grow vegetables efficiently. The
water from the aquarium is pumped by a water pump through a pipe into a gravel
grow bed which the plants grow in. The fish efficient ammonia filters through
granite chips in the grow bed. Bacteria convert ammonia to nitrites and then to
nitrates. This is the basic form of plant protein. It is absorbed by the plants
and the water flows back into the aquarium.
Ammonia is toxic to fish, but
after it has been through the natural filtration system in the grow bed the ammonia
is removed by the plants. This water is clean and can be recycled. This is a
self-sustaining system.
The Impact on Africa
Aquaponics does not depend on
location so it is used in urban and rural areas. People in Kenya have benefited
from using aquaponics to gain a greater income by setting up a system similar
to this one. They grow plants in their spare time and can sell the fish and
food produced. It is also a cheaper and healthier diet so anyone that uses this
system can benefit from it. Poor children in less economically developed
countries can go to school because they will not have to search for food.
Aquaponics does not depend on soil quality so it can be used anywhere in
Africa.
Pig
Manure as an Energy Source
Amanda Kane, Brittany King and Avina Trivedi
chose 'Generating Electricity from Pig Manure' as their topic for the science
fair because they were intrigued by the way in which it works and believe it to
be capable of becoming a main source of renewable energy if implemented on a
larger scale. Upon visiting a farm in Zimbabwe which has implemented this
method of producing energy, they realised that this method is self-sustainable,
eco-friendly, effective and once implemented, does not cost much.
With future power shortages and
many rural areas existing without access to power, this method should prove to
be a reliable source of electricity for many. They were pleased to have been
placed third in the science fair and hope that in the future this method is
implemented.
A summary of the model on which they based
their project is illustrated in the picture above.
They
particularly liked this method because it is:
ü -Eco-friendly as the digestive fluid
produced in the separation and fermentation processes can be sprayed as liquid
fertilizer. It is also converted into solid fertilizer and can then be sold and
therefore this method produces a minimal amount of waste.
ü -Self-sufficient as the
waste heat from the engines of the generator can often be used to run the
digester.
