[Stoves] Drinking straw that eliminates the need to cut any firewood at all

Richard Stanley rstanley at legacyfound.org
Mon Dec 26 13:01:36 CST 2011


Re water filtration by natural and affordable means:

Has anyone been following the development of solar distillation using PET soda drinking bottles..ie., the SODIS method .

If not, may you  kindly get a cuppa java and enjoy the wicki link below:
 
This is the right  way to move and it have lots of broad and deep research interested to back it up.  Organic pathogens  ok:  toxics from industry not. PET bottles fine certain PVC polycarbonate and plastic and even certain glass bottles not. Water with high  turbidity needs filtration first ---or one flocculates using certain natural seeds as flocculants (more effective than alum for eg).
Duration and reestablishment of pathogens at night an issue but its all being  researched broadly and currently…

This is where the carbon credits should be going… 
enjoy;
http://en.wikipedia.org/wiki/Solar_water_disinfection

R Stanley
www.legacyfound.org
NW Obamaland

 
On Dec 25, 2011, at 2:46 PM, Andrew C. Parker wrote:

> Interesting.  Things have certainly improved since I last researched this sort of stuff, about 15 years ago.  It took some digging on their site before I found any meaningful information, but it is there.  I would tend to agree with the Stanford article.
> 
> Filter membranes are expensive and finicky.  The Family unit requires a replaceable (refillable?) chlorine cartridge to keep biofilm from fouling the membrane.  Many reverse osmosis systems also require that feed water be softened because of the risk of hard water deposits fouling the membrane.  I do not know if this microfiltration design suffers the same problem.
> 
> An additional concern is that there are some things LifeStraw does not filter that can do harm.  Water ought to be tested for heavy metals and toxins before people are told that microfiltration will give them healthy water.
> 
> Membrane filters certainly have their place, but successful use requires training and an understanding of how it works, what it can and cannot do, and the ability to test the water regularly to assure that everything is still working.
> 
> Saying that, if someone wants to give these away, fine, but it is only a short term solution.
> 
> Another problem is that treated water is only part of the equation.  Hygiene is a major factor. Dirty hands and dirty vessels nullify the benefits of the treated water.
> 
> I agree that point-of-use treatment is a major benefit in developing countries (and a few developed ones as well.  Even in metropolitan areas with conventional treated water systems the distribution systems (mostly low-pressure) are often compromised by illegal perforations and bad plumbing that allow siphoning of contaminants into the system.  My in-laws in Ecuador always boil their drinking and cooking water (Ecuador subsidizes propane for cooking, so no wood or charcoal is burned), and some people boil bath and laundry water as well (after bath/shower disinfectants are a big seller).  It is nice to have clear water from the tap, when it works, but by the time it reaches the customer, it may still appear clear but has been contaminated with who knows what.
> 
> 
> Andrew Parker
> 
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