17th March 2013 at 2:33 pm #828
I read where iron oxide (rusty nails) can bond with Arsenic.
Has anyone tested using a surfactant to improve filtering? My logic is a small dose of surfactant could break the surface tension of the water to let metal bits stick to the sand better.
Next, it sure seems to me you could use thick plastic garbage bags, and a hole in the ground to build a sand filter. Much easier to ship plastic bags and some tubing then a concrete barrel. and I would think most folks might have a shovel already?
17th March 2013 at 2:33 pm #829
Yes, we need some new ideas on how filters can be made more accessible for low-income families. But the solutions also have to be robust and practical. For instance you need a water collection point where the water is collected, so if the filter is in the ground, the collection point also must be in the ground, but it’s doable I guess. One advantage of the concrete filter is that it is inside the household where people use the water. Now if you can come up with a design for a collapsible filter that can be put up in the house, and which can be sold for $10-15 in the bush (after shipping, transport etc is factored in) then we might be onto something.
17th March 2013 at 2:34 pm #830
The nail or (any steel) in the sand will react with the O2 in the water, converting it to Iron Oxide. The O2 will not be available for the microbes, killing the biofilter.
17th March 2013 at 2:35 pm #831
I think you’ll need to back up your assumptions about iron with any academic studies done on it? I know that MIT did a load of research in Bangladesh with water passing through rusty nails prior to entering the sand filter, and they performed excellently.
17th March 2013 at 2:37 pm #832
I’m working on a theory design for a sand filter and would love to read any research about the rusty nails. Do you have any links?
17th March 2013 at 2:40 pm #833
If you send me an email (see contacts part of the site) then I’ll send you what docs I have on arsenic removal and BSFs.
17th March 2013 at 2:41 pm #834
I agree with Diugs idea of using material other than ferrocement as is done many NGOs. The ferrocemt filter are expensive to make and back breaking in terms of logistics. I have been using HDPE /PVC pipes of 6 inc dia . They can be made as DIY by individuals or fabricated by NGOs. I feel people coming into the field new should not start the ferrocemt model. I have done extensive reserch on this subjects using heavy contamination with E – Coli and found plastic model work as well or better than ferrocemet models.
I have found out through extensive reserch that the height of the filter can be reduced by half with the same efficiency of as of the version -10 model. I now use quotas sand for the bio layer with lower bed of manganese green sand to remove iron and other heavy metals. This mix gives several times capacity for turgidity removal also. Try it out . Pls contact me in the follwing e-mail I’d for further assistance .
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