AfriGadget

Solar water disinfection (SODIS) has been around for quite some time now and with approx. over 340.000 users in Africa alone, this low budget water disinfection “technology” is a smart approach that deserves to be mentioned on AfriGadget.

In areas where piped drinking water just isn’t available or of questionable quality, solar water disinfection is a cheap and effective method for decentralized water treatment as it can be applied at household level. It is a simple method that’s easy to teach and is designed for small scale production.

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SODIS uses solar radiation to destroy pathogenic microorganisms which cause water borne diseases:

Sunlight is treating the contaminated water through two synergetic mechanisms: Radiation in the spectrum of UV-A (wavelength 320-400nm) and increased water temperature. If the water temperature raises above 50°C, the disinfection process is three times faster. (source)

The World Health Organization (WHO) even recommends SODIS as a viable method for household water treatment and safe storage.

All you will need are clean & transparent PET bottles, fill them up with water and expose them to direct sunlight for at least 6 hours . Many people also put them on a corrugated roof (to increase temperature) and saturate the oxygen content inside the bottles prior to the sun treatment by filling them up three quarters, shaking them for 20 seconds with a closed cap on and then fill them up completely.

(source)

SODIS may also replace the boiling of water which often requires vast amounts of firewood or other natural resources, so it not only helps people obtain safer drinking water (conventional filter candles are expensive and not always available) but also helps to preserve the local environment.

SODIS obviously can’t substitute really clean drinking water, and it often also requires pre-treatment in case the water turbidity is too high . Users can easily reduce the turbidity though by letting the bottles stand for a while until the particles settle to the ground and then also filter it through a folded cloth.

The best aspect about SODIS though - despite of it’s low budget approach - is that consumers are directly in charge of their drinking water and have a working method that enables them to treat their own drinking water.

The Swiss Federal Institute of Aquatic Science and Technology (Eawag) also published a very informative website on SODIS and provides more details about the technology as well as case studies from around the world.

Kibera from space

Google Earth is one way to appreciate the crush in Kibera, Africa’s largest slum. Not surprisingly popular images of people living in desperate conditions aren’t far from the truth when it comes to this corner of Nairobi - but out of the madness comes a little hope.

Raw sewage flows above ground

I witnessed some amazing innovations in Kibera and conclude that people have adjusted to their situation and are making the most of it.  Because of the stress associated with limitations on land, energy, water, and food the people have found innovative ways of surviving. This post is mainly about farming.

Vertical farming

like this guy and his vertical garden which feeds his family and he even sells some produce. It’s a variation on what JKE wrote about in the post on Keyhole gardens in Botswana.

Like the key hole garden of Swaziland, this veggie patch serves a family on a tiny piece of land

Finding land in rubbish

Now a local organic farming company Green Dreams has been documenting the progress of transforming a garbage dump to an organic farm on the Green Dreams blog. They are working with a local youth group comprising reformed criminals in converting garbage into organic manure, and garbage dumps into organic farms.

Before the clean up and farming

Clearing land of garbage

installing irrigation

Irrigation taps the mains water and supplies nutrient rich feeds from organic fertilizer produced on the site from crops and worms, yes they harvested local earthworms to start vermiculture.

Worm farm - just a tray with kitchen wastes feeds a bunch of earthworms that produce organic liquid manure

Planting seedlings, cleared waste is bundled under shade cloth and planted with pumpkin to create a green soil erosion barrier

Check out the planting implements, a PVC Pipe adapted to deliver seeds into a perfectly dug hole!  This was invented to help with the back breaking work of planting.

Scarecrow

Garbage dump transformed this is the Kibera organic farm - 3 months after clearing the dump

After 3 months the community of 30 families were harvesting, eating and selling organic produce. Yum! Impossible to ignore how a dirty dump turned green, everyone wants a farm in Kibera now. This group is now selling their expertise to raise funds and help others.

Natural Bean Tenderizer

There was a smouldering fire where banana leaves were being reduced to ash, then the ash dissolved in water and the brown murky astringent solution sold for Ksh 50 ($.80) per 250 ml in vodka bottles! This is a bean tenderizer reducing the time to boil red kidney beans by 50%! Imagine the savings on charcoal/fuel.

Safe Dispensing of Fuel

Kerosene is dispensed from a caged petrol pump for security

Notice that there was no protection around the farm or it’s equipment. Apparently the reputation of these ‘reformed criminals’ is enough of a deterrent.

Kids in Kibera

Life might be hard in Kibera but yet when you visit you can’t ignore the vibrancy, colorfulness, camaraderie amongst the inhabitants it was one time that I got the feeling that people here love life

Ingenuity, obviously, isn’t only limited to the African continent, as it is especially found in societies where access to resources is limited. While we’ve been able to witness lots of interesting innovations from other regions of the world that were born out of a lack of readily available solutions, we must also not forget that a few smart ideas were actually developed in Africa and have since then conquered the world.

One of such smart ideas is the Ventilated (Improved) Pit Latrine, in short: the VIP – which was developed as the “Blair Latrine” by Peter Morgan, who has been living and working in Zimbabwe for over 35 years, researching and developing water and sanitation technologies.

Diagram showing effect of vent pipe on functions of pit latrine (source)

The major advantage of the VIP over a normal pit latrine is that it comes with a ventilation pipe (covered with a durable fly screen on top) which reduces flies and odour. In the absence of other alternatives, the Ventilated Pit Latrine is considered reliable, which explains the success of this technology: over 500.000+ units of this type have been built in Zimbabwe alone and it has proven to work elsewhere around the world.

The VIP clearly isn’t the solution to sustainable sanitation as it comes with a few limitations, but it does function without water and has very low investment, operation and maintenance costs.

Next to some interesting experiments with different water pump systems such as the Blair hand pump (also known as the Zimbabwe Bush Pump) or the spiral water wheel pump, Peter is also active in the field of ecological sanitation and recently published a very interesting booklet titled “Toilets That Make Compost” where he writes about his experiences with compost toilets such as the Arborloo and the Fossa Alterna.

screenshot from Peter Morgan’s manual on how to build an Arborloo (PDF,~ 3,1MB)

While there’s no single sanitation concept that will work in all places around the world, the VIP for one is a proven technology which has been accepted by its users since 30 years.