[at-l] another water purifier

[Logan Park]

Bleach (sodium hypochlorite) and Aqua Mira (chlorine dioxide) both use 
variations on the chlorine theme.  Bleach works because it is strong 
stuff used in relatively high concentrations.  Aqua Mira works because 
chlorine dioxide is actually a gas (in our application, dissolved in 
water much in ht e same way a coke is carbonated), so it is pretty good 
at getting past the chemically resistant cyst outer layers.

The EPA has not to my knowledge released standard testing data on AM, 
but this US army evaluation notes that AM will reduce Giardia counts by 
a 3-log factor (a factor of 1000 IIRC).  See 
http://usachppm.apgea.army.mil/WPD/WPDSHARE/143/AddInfo_McNettAquaMira.pdf#search=%22Aqua%20Mira%20McNett%20giardia%22
Sorry for the long URL!

In the following EPA report, 
http://www.epa.gov/ogwdw000/mdbp/pdf/alter/chapt_4.pdf
page 15 et seq. describe chlorine dioxide as more effective than 
bleach.  It is a great read if you have a healthy sense of humor 
(chlorine dioxie is highly explosive, which is why we generate it onsite 
when hiking).

So, short story long, Aqua Mira does in fact kill giardia, and better 
than does bleach.  Neither is particularly good against 
cryptosporidium.  YMMV.

Hoplite


Point North wrote:
> Aqua Mira doesn't kill giardia, does it?
>
> What about bleach?
>
> Logan Park <park at vt.edu> wrote: David Addleton wrote:
>   
>> http://www.nytimes.com/2006/10/10/science/10find.html?_r=1&ref=science&oref=slogin
>>
>> I imagine it will need only a tweak or two to make it useful against giardia
>>
>>   
>>     
> Yus-- sadly the cyst is 1-6 microns (the filter is 6).  The tradeoff for 
> a more effective filter is, of course, that it catches more and 
> consequently would get surface saturated more rapidly.  For the water 
> quality research I did in college, we'd use 0.6 micron filters, and 
> they'd clog after ~2 L filtered under 2-3 atm of nitrogen pressure.  
> Aqua Mira for me.
>
> HopThirsty
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