Saturday, July 25, 2009

Design Reviews IDDS

Yesterday IDDS held design reviews on the 12 projects. These were held at ITTU, in the Suame area (an area with many small industrial workshops). Due to the format, I could not attend all the reviews.

I watched two teams who are working on chlorine purification approaches. It surprises me that chlorine is inexpensive and effective, yet not widely used to purify water. Why is this? Are more complicated technologies needed? The first team is looking to make a low cost chlorine manufacturing device. Using salt water and electricity to produce chlorine. The team was trying to figure out a way to do this without using expensive high power batteries. The second team was planning to use commercially available chlorine, but was working on a reliable way to dose water in smaller communities. They were also looking at business models- water committees, cooperatives or entrepreneurs- to distribute the device.

The other two reviews I watched were working on small scale energy. The first was looking for an alternative to batteries for LED lights. They had examined hand cranks, bicycles and salt water batteries (I had not heard of these before). They were also intrigued by a light we had seen in the villages that used an old music CD as a reflector and provided decent room lighting with 1w LED bulbs. The second team was working on a way of keeping produce from spoiling between the fields and the market. The cost of transport is not just the time and vehicle, but also the loss of up to 30% of a shipment before it is sold. This team has been looking at several alternatives to "pot in pot evaporation" which works well in dryer climates but not humid climates (West Africa). Their current design uses insulation, a small fan and inexpensive webbing materials.

The teams got good feedback from reviewers, a mix of development folks, business people, Suame artisans and engineers. Today is a rare "day off" and tomorrow will be back to work with prototyping and some "Build It" sessions (participants showing others how to make stuff).

1 comment:

McKay said...

Find your articles interesting to read, but one comment on this one: why do you say chorine is not widely used for water purification? It is in fact the main method used for all Western cities for their drinking water supplies. Maybe you just forget it's called "water treatment".

Bottled water companies don't often use chlorine because of the taste, preferring reverse osmosis, UV and filtration.

Chlorine (often as chlorine dioxide) is also widely used in wilderness and travel personal water purification systems, but it is however, not effective against all microbes and viruses so that is why perhaps it is looked over for small-scale water purification schemes against micropore filters, iodine tablets or UV.

So it is often considered and I would expect it to be a go-to for many companies. Perhaps the groups you've seen trying it just haven't tried it or found it unsuitable (again taste and toxicity are key factors). Chlorine, as all chemicals, does require very specific amounts and knowledge to use effectively so that can limit its solution for general public. If you don't put enough in or don't leave it long enough, it doesn't work.

Just some more background on the subject.