[Stoves] Water Disinfection - Mix Boiling Water and Unheated Water to Pasteurize

[K McLean]

Your disinfection by darkness method should be easy to test in a lab.  If
successful in the lab, I can think of many ways it might be easily
implemented.

Despite decades of effort, 2.2 billion people (67%) in the 60 developing
countries analyzed in this study
<https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2813171/> do nothing to treat
their water.  Of those that treat, 500 million use adequate methods.

If you think your disinfection by darkness method has potential, help find
a lab and I'll pay for the testing.  It doesn't have to be the best
solution, just a good method that can be quickly disseminated.  Let's not
let the perfect be the enemy of the good.

Kevin


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On Mon, Sep 23, 2019 at 1:34 PM Crispin Pemberton-Pigott <
crispinpigott at outlook.com> wrote:

> Dear Kevin
>
>
>
> This suggestion comes from my work in rural water supply in Swaziland.
> With 4 others we set up a national water supply branch of the Water and
> Sewerage Board with WUSC and ODA (UK).
>
>
>
> One of the problems in the Swazi lowveld is bilharzia which is contracted
> by drinking or swimming in infected waters. It is spread by snails and
> peeing into a water source.
>
>
>
> The very simplest method of reducing the contamination burden in water is
> to store it for three days in the dark.  The main purpose was to implement,
> quickly, something that would reduce the transmission and reinfection. The
> solution turned out to be good at killing all sorts of things that depend
> on sunlight.
>
>
>
> For this reason, the systems we were building were created to have >3 days
> storage, and to be covered completely. As long as the water took three days
> to get through the system, it would be “improved” in the absence of other
> treatments.
>
>
>
> I have never seen a systematic study of the relative merits of these
> approaches on real water samples.  In a rural situation where the families
> are stable, it is best to use slow sand filters with precautionary chlorine
> or iodine.  This requires good management which means good training of two
> or three specialists who will take care of the filters. It’s a pretty lazy
> job, but systematic.
>
>
>
> Rapid sand filters require power to run as a system.  If power is
> available, ultraviolet light is pretty good. I do not know what effect that
> has on spores, and at what temperature that happens.
>
>
>
> The silvered porous clay pots are very effective.  There is a similar (in
> appearance) system invented by a Canadian for removing arsenic from water
> in Bangladesh.  Very effective and low cost.
>
>
>
> It’s a big subject.
>
> Regards
>
> Crispin
>
>
>
>
>
> *From:* Stoves <stoves-bounces at lists.bioenergylists.org> *On Behalf Of *K
> McLean
> *Sent:* Monday, September 23, 2019 1:06 PM
> *To:* Discussion of biomass cooking stoves <
> stoves at lists.bioenergylists.org>
> *Subject:* Re: [Stoves] Water Disinfection - Mix Boiling Water and
> Unheated Water to Pasteurize
>
>
>
> Hi Crispin,
>
>
>
> You said "keep [water] in a storage system that excludes all light. Nearly
> everything dies (but not all, of course)"  I cannot find any research on
> this.  Do you happen to have any?  This could be a method to disinfect
> without cost..  Seems like well water should be disinfected, though.
>
>
>
> Kevin
>
>
>
>
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> On Mon, Sep 23, 2019 at 10:40 AM Crispin Pemberton-Pigott <
> crispinpigott at outlook.com> wrote:
>
> Dear Andrew
>
>
>
> The most important question is what do those temps kill: everything that
> is bacterial.
>
>
>
> Spores are a serious problem and prions even worse. Tough little things.
> They are not really alive and some coat themselves when “challenged”.
>
>
>
> >>Low cost WAPI's wax indicators can tell you 70C is achieved visually
>
>
>
> >Thanks for that Tony, I too find this interesting and having a means of
> indicating the certainty of adequate treatment  would reassure me, who
> drinks, bathes and cleans with water supplied by a pipe with guaranteed
> levels of hygiene.
>
>
>
> There is a long-standing programme to promote the distribution of those
> devices in low water quality areas.
>
>
>
> >We had a  potter who used to contribute, now deceased , his name escapes
> me, who made pottery filter jugs which he precipitated a thin late of
> silver in as a bactericide
>
>
>
> Those work very well and remove the need to boil.  Also a slow sand filter
> (properly managed which means having two in parallel) so, ditto. We always
> added chlorine as a precaution, with 2 ppm of free Cl at the end of the
> longest line at the last tap. That takes care of pipeline contamination.
>
>
>
> Caution for those planning to test the bacteria after any processing –
> read how to do this sampling well. You have to “flame” all the containers
> and the tap before taking the sample. Contamination is *very* easy. I
> would not believe a positive result collected by an untrained staffer.
>
>
>
> >Interesting chart Crispin but it doesn't show what each of those
> treatments achieve, or do they all do the same thing to all microbes?
>
>
>
> All microbes usually found in water.  Surely there are exceptional cases?
> Deep sea critters? More escapes heat than I assumed.  It helps to know what
> is in the water before starting to test a treatment regimen.
>
>
>
> >What temperature does kill anthrax, tetanus and botul;sm spores?
>
>
>
> Looks like 150 C.  They are no so much killed as destroyed. I think they
> are not alive in the first place.  “Life” has a loose definition.  A great
> many water-borne pathogens are killed simply by being in a fully darkened
> tank for three days. If you have no treatment available at all for washing
> water, keep it in a storage system that excludes all light. Nearly
> everything dies (but not all, of course).  Such simple treatment will kill
> bilharzia, for example.
>
>
>
> Drink safe…
>
> Crispin
>
> Ex-Clerk of Works, Rural Water Supply Program, Hhohho District, later
> Lubombo District, in (then) Swaziland – one of the lighter squares on the
> board of my chequered career
>
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