Water purification plants
Can you offer any suggestions/pointers for portable/small-ish water purification plants for use by nomads, either to move around or leave at wells? My mind is drawn towards the "survival kit" sold to campers but I'm not familiar with recent developments.
I've yet to get a proper analysis but from other reports I suspect that both mineral and bacteriological pollution is likely, with the latter being the cause of the main local health problem - childhood diahorrea.
In Iraq we put in RO plants and arranged for deliveries (I wonder if they are still functioning?) but here there isn't the same public service culture to run it.
Any help at all that would focus my internet search would be very welcome.
You don’t say where you are working but I’m imagining some sun drenched area of the Sahara? Probably completely wrong Have you considered solar disinfection? http://www.sodis.ch/ For improving mineral quality, you would need to get the water tested so that you know which mineral you are talking about and the degrees of concentration.
Depending on the water source you will probably need a combination of filtration and chlorination to deal with bacterial contamination.
The filtration could be a simple gravity sand filter if you are looking for something for a community or a ceramic filter if you are providing treatment on a family level. If there is no organisation for the maintenance of public assets, I would suggest that you go to the family level.
A sand filter could be made out of in an oil drum filled with sand. Water would flow in at the top and be collected from the bottom. Part of the treatment comes from biological action by bacteria that develops in the top layer of sand (exposed to sunlight) and this would clog up periodically and have to be replaced.
Ceramic filters come in various shapes and sizes, sometimes with a twin bucket system with water flowing through the ceramic filters from the top to the bottom bucket. Simpler still are ceramic filters with a siphon tube. The dirty water is put in a bucket or pot at a higher level and flows to the siphon to the lower level container.
Chlorination may be necessary, though the filter should remove most of the bacteria. There are guidelines in several books that I have at home but unfortunately I am currently working in Namibia. They are probably in the RedR book "Engineering in Emergencies". It depends on the volume of water and the strength of the chlorine used. Water should be allowed to stand for a few hours after chlorination to allow the chlorine time to kill bacteria before it is drunk. As a rule of thumb, if you can taste the chlorine it is a slightly stronger solution than it needs to be.
Moving up a level, there are simple plants that combine filtration and chlorination. I have seen a British Army one some years ago on a RedR course. These, however, are likely to require a strong commitment to operation and maintenance.
Mineral contamination is much more complex and would depend on the precise contaminant involved. It is very expensive and technically difficult to remove dissolved minerals from water.
I belief GTZ published a book documenting existing traditional ways of treating water by nomadic people. I Know there is a copy of that book in the University at Loughborough and you could probably obtain copies of part of the book through the WELL document service at WEDC.
If you look for individual treatment it might be worth considering a ceramic filtering straw. The idea is based on the guinea worm filtering straws used in South Sudan. For more centralised systems you will have to give more info as none of the small plants are simple. Even slow-sand-filter plants which are simple will require a basic understanding of the underlying principles.
In my experience, even where there is bacteriological5pollution, proper hygiene (hand washing after defecation gives excellent results. Wells can be protected, and if used properly bacteria. pollution can be reduced / stopped. Why not find out if they are polluted? - Del Aqua or similar for field tests. You may not need to treat the water.
In terms of survival kit type portable solutions, as well as the ceramic filters that Martin and Krystof mention, the following UF membrane filters will disinfect. In oder of increasing size:
However if minerals are a real issue desalination may be required. Survival kit RO systems do exist, but tend to be much more expensive. In order of increasing size:
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