Hello Owice,

Could you tell me how I can download the pdf? I do have/want Dropbox.

You might be interested by the work shown on small BSFs at:
preserve.lehigh.edu/cgi/viewcontent.cgi?...cle=2570&context=etd

Graham K This email address is being protected from spambots. You need JavaScript enabled to view it.

Hello,

I finished my masters in Integrated Water Resources Management and my thesis was mainly about using biosand filters to enable the poor.

My thesis included a literature comparison of different household treatment options. I built and used a biosand filter from local materials in Jordan. It was relatively cheap and very affordable. It costed around 19$.

You can access my thesis in the following link :
www.dropbox.com/s/hurpj4ts4wtr4j8/Edited%20thesis.pdf

I am ready for any further quedtions/explanations.

Do you actually have a scientific source that backs your cloth filter claim? I am not disputing that it might reduce the quantity of cholera bacteria through turbidity reduction, but do we really want people to drink cholera contaminated water with an only partially effective filter? I am quite sure that any such studies were related to worst case emergency situations where any treatment is better than nothing.

Your link leads again to a different topic than you mention in the text, but yes a biosand filter does not really need a very thick sand layer (as already written above). However a flimsy bucket solution is easily disturbed and damaged as they also write in your link.

Last but not least, nearly any source of water can be improved or nearby better alternative developed. For a river you can install a riverbank filtration hand pump for example and so on.
All of that will be much more sustainable than band aid household water filters, and the health impact will be bigger too as all the water used will be improved, not just the tiny percentage that gets filtered for drinking.

Dear J K Makowka,

You seem rather too ready to dismiss the recent work on filtration from water experts.
For example sari cloth filters have been tested to show their use can, and does, eliminate cholera.

What you also ignore is that conditions for billions are so bad that any filtration will serve some purpose!
Your statement, .."it makes much more sense to improve the source quality and the way water reaches (and is stored in) the households than to treat a small part of that water" makes no sense for the many far from any quality water source!

You might read; preserve.lehigh.edu/etd/1570/

Hello,

I have been reading your thread and I would like to encourage Graham to have a look at this other thread, and reply in the thread or eventually to get in touch with me directly: forum.susana.org/forum/categories/193-gr...-membrane-technology

Graham, I believe that even though people have little financial means, they should not be kept away from the safest available technology. To date ultrafiltration is one of the best technical solutions for households living in rural area (with little or no electricity). I would like to highlight the fact that our filters for example are designed to last years (minimum of 5 years) without need of spare parts or cartridge... We are a not for profit company). I am not saying that they are cheap for a poor family in a developing country (depends on the family and the country...) but if you are having programmes in such a country, solutions such has micro loans could be explored.

I would also like to say that mobile phones are not cheap either but almost everyone has one, including in developing countries. The safe technology exist (our filters and many others) but people do not always perceive the need for safe drinking water as essential (when having a mobile phone is perceived as essential). I am not judging people, they know better how to spend their money and their view might be different from ours. Therefore my conclusion is that if you want people to use a water filter (which will protect them from bacteria, viruses etc...), do not try to lead them to solutions that proved to be difficult to apply (and are not always safe) but make the most efficient technology appealing to them (like the mobile phone). I believe that if that is working with latrines in countries like Cambodia it should work in other countries with "high-tech" water filters.

Once again feel free to post on the forum or to write to me directly if you want to explore further ultrafiltration solutions (quote David at This email address is being protected from spambots. You need JavaScript enabled to view it.)

Best,
David

www.grifaid.org

GrifAid, 16 Burdon Road,
Cleadon, Sunderland,
SR6 7RU
UK

GrahamK wrote: Cloth filters in India use sari cloth and have been shown to remove most bacteria including cholera!

That's some dangerous miss-information (that is also not written in the link you provided).

Cloth filters are way too coarse to remove bacteria (not even talking about viruses); they might - through the removal of much larger objects to which some bacteria commonly attach to - be able to reduce the overall bacterial load, but water of such bad source quality will still contain too many pathogens even after cloth filtration to be reasonably safe to drink.
Only in combination with chlorination do they make a certain sense, as removing the turbidity allows the chlorine to work much better.

The reason why there seems to be much less interest in household water treatment (after an unreasonable hype in the early 2000s), is that in most cases it makes much more sense to improve the source quality and the way water reaches (and is stored in) the households than to treat a small part of that water.

Only after the source and transport is reasonably safe, it would make sense to start with some sort of treatment in the household. But for that, most simple/cheap/locally produced methods are simply not good enough, and with bad maintenance they often turn into a source of contamination rather than a protection against.

Edit: The other link you provided is about metal-oxide coated sand filters, which is a chemical surface coating of sand particles to improve the filtration efficiency of rapid sand filters. Neither has this much to do with bio-sand filters (where the effective pathogen removal happens in the "schmutzdecke"), nor is it in any way doable by just adding steel nails to a sand filter... and last but not least, it doesn't "kill" viruses but improves the retention of them in the filter bed.

Cloth filters in India use sari cloth and have been shown to remove most bacteria including cholera!
Visit en.hesperian.org/hhg/A_Community_Guide_t..._Water_Safe_to_Drink and others.

Putting steel nails into biosand filters kills viruses.
Visit www.eng.warwick.ac.uk/ircsa/pdf/13th/Ahammed.pdf and others.

It should be able to combine these 3 elements but no-one seems to be working in this field any longer!

The design I linked should be a small & very affordable household version of a bio-sand filter.

I doubt that a cloth filter will offer significant improvements in water quality besides removal of some turbidity, that would be better done by improving the water source.

An actually working alternative would be those ceramics filters that can also be produced locally, see for example: pottersforpeace.com/?page_id=63
But these are much more difficult to build and require a certain level of technical expertise that might be difficult to come by in many places.

Biosand filters are usually large and too expensive for poor people.
What is needed is a new small version incorporating a cloth filter as widely used in India!

This will probably help:
resources.cawst.org/package/biosand-filt...nstruction-manual_en

However maintenance is usually lacking and unused biosand filters with stagnating water inside quickly turn into mosquito breeding pools.

I am looking for help with water filtration for my contacts in rural parts of developing countries.
Most do not have the means to buy modern filtration devices!
What they have may be little more than a bucket but this could suffice for a biosand filter according to filtration experts who were developing filters in the past!

But for the last 10 years interest in helping the rural poor has much diminished!
Is there anyone who can point me in the right direction?