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Water Purification Tablets
18 November 2016, 04:10,
#11
RE: Water Purification Tablets
Some helpful references:

http://www.berkeyfilters.com/?gclid=CN2o...aQodnq4PeQ

http://wananchi-uk.com/?gclid=CIjwzfCpsd...aQodDUUNfQ

http://www.lifewater.ca/drill_manual/Section_16.htm

http://www.armystudyguide.com/content/Pr...alis.shtml

http://www.waterworld.com/articles/print...obile.html

http://www.lamotte.com/en/education/water-monitoring

73 de KE4SKY
In
"Almost Heaven" West Virginia
USA
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18 November 2016, 12:44,
#12
RE: Water Purification Tablets
(18 November 2016, 04:10)CharlesHarris Wrote: Some helpful references:

http://www.berkeyfilters.com/?gclid=CN2o...aQodnq4PeQ

http://wananchi-uk.com/?gclid=CIjwzfCpsd...aQodDUUNfQ

http://www.lifewater.ca/drill_manual/Section_16.htm

http://www.armystudyguide.com/content/Pr...alis.shtml

http://www.waterworld.com/articles/print...obile.html

http://www.lamotte.com/en/education/water-monitoring

Some excellent references, thank you Charles.
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18 November 2016, 19:01,
#13
RE: Water Purification Tablets
+1 for Berkey filters.

If your water is clear then look at http://modernsurvivalblog.com/health/how...-sunlight/ I'd only use this as a last resort though.

https://www.youtube.com/watch?v=QUIgnoMTh0I This is well, well, worth watching.
ATB
Harry
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20 November 2016, 01:34,
#14
RE: Water Purification Tablets
(18 November 2016, 19:01)harrypalmer Wrote: +1 for Berkey filters.

If your water is clear then look at http://modernsurvivalblog.com/health/how...-sunlight/ I'd only use this as a last resort though.

https://www.youtube.com/watch?v=QUIgnoMTh0I This is well, well, worth watching.

Thank you Harry I shall take a look.
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20 November 2016, 01:54,
#15
RE: Water Purification Tablets
Info from the US Centers for Disease Control on SODIS:
http://www.cdc.gov/safewater/solardisinfection.html

Solar disinfection (SODIS) was developed in the 1980s to inexpensively disinfect water used for oral rehydration solutions. In 1991, the Swiss Federal Institute for Environmental Science and Technology began to investigate and implement SODIS as a household water treatment option to prevent diarrhea in developing countries. Users of SODIS fill 0.3-2.0 liter plastic soda bottles with low-turbidity water, shake them to oxygenate, and place the bottles on a roof or rack for 6 hours (if sunny) or 2 days (if cloudy). The combined effects of ultra-violet light (UV)-induced DNA damage, thermal inactivation, and photo-oxidative destruction inactivate disease-causing organisms.

In the laboratory, SODIS has been proven to inactivate the viruses, bacteria, and protozoa that cause diarrheal diseases. Field data have also shown reductions of viruses, bacteria, and protozoa in water from developing countries treated with SODIS. In four randomized, controlled trials, SODIS has resulted in reductions in diarrheal disease incidence ranging from 9-86%.

The benefits of Solar Disinfection are:

Proven reduction of viruses, bacteria, and protozoa in water
Proven reduction of diarrheal disease incidence
Simplicity of use and acceptability
No cost if using recycled plastic bottles
Minimal change in taste of the water
Recontamination is low because water is served and stored in the small narrow necked bottles

The drawbacks of Solar Disinfection are:

Need to pretreat water of higher turbidity with flocculation and/or filtration
Limited volume of water that can be treated all at once
Length of time required to treat water
Large supply of intact, clean, suitable plastic bottles required

SODIS is most appropriate in areas where there is availability of bottles and community motivation and training for users on how to correctly and consistently use SODIS for treating household drinking water.

Implementation Examples

Over 2 million people in 28 developing countries use SODIS for daily drinking water treatment.

Experience has shown that SODIS is best promoted and disseminated by partner institutions based in the project area. Important partners are community-based organizations (CBOs) such as women's clubs, youth associations or self-help groups, well-established NGOs working on community development projects, institutional organizations such as health posts, hospitals, and teacher training centers, and government programs. Individuals, such as community and religious leaders as well as politicians and decision-makers, play a key role and should be involved from the beginning of a project. SODIS promotion in a new area usually begins with a pilot project of one year that reaches 2000-4000 families. In the second year, the project expands into the field of advocacy to scale-up the project.

The CBO Kenya Water for Health Organisation promotes SODIS in the Kibera slums of Nairobi, Kenya. Over 250,000 people are reached by trained promoters using social marketing to disseminate knowledge about SODIS. Research-based information is given out by promoters to potential users, especially when users are skeptical about SODIS.

In Latin America the promotion is channeled through a regional reference center, Fundaçion SodisExternal Web Site Icon. Their strategy is to build and strengthen a network of partner institutions; they do not implement projects, but focuses on training trainers, technical assistance, and lobbying activities. More than 100,000 people are using SODIS in Latin America.
In Assam, India, Assam University provided technical and training support for a SODIS promotion project with a local NGO. The dissemination phase targeted 20,000 households based on lessons learned during the pilot phase. An approach involving active participation of institutions such as village councils, schools, and health centers was adopted to ensure the project is community-owned and sustainable.

Economics and Scalability

SODIS, as a virtually zero-cost technology, faces marketing constraints. Since 2001, local NGOs in 28 countries have disseminated SODIS through training of trainers, educating at the grassroots level, providing technical assistance to partner organizations, lobbying key players, and establishing information networks. The experiences gained have shown that SODIS is best promoted and disseminated by local institutions with experience in community health education. A long-term training approach and repeated contact with the community is needed to create awareness on the importance of treating drinking water and to establish corresponding changes in behavior. Both the Swiss Federal Institute of Aquatic Research and Technology and the SODIS Foundation provide technical assistance to NGOs implementing SODIS.

73 de KE4SKY
In
"Almost Heaven" West Virginia
USA
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20 November 2016, 18:20,
#16
RE: Water Purification Tablets
Why do the UV rays kill the bugs in the bottle and not in the puddle?
__________
Every person should view freedom of speech as an essential right.
Without it you can not tell who the idiots are.
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20 November 2016, 19:22,
#17
RE: Water Purification Tablets
MB,

Turbidity.

73 de KE4SKY
In
"Almost Heaven" West Virginia
USA
Reply
21 November 2016, 17:46,
#18
RE: Water Purification Tablets
At what ambient temperature does this stop working?

I suspect much of the effectiveness is due to the temperature of the water inside the bottles placed in the sun in Nigeria, New Deli or HoChi Minn City reaching over 140f-150f, the temps where most creepies die on their own.

Is it effective at 35-38f?
__________
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21 November 2016, 20:52,
#19
RE: Water Purification Tablets
http://www.sodis.ch/methode/faqs/index_EN

If the temperature is increased, the efficiency of the SODIS method can be improved. The germs are killed more quickly. In addition, amoebas are also rendered harmless above a temperature of 50°C. To increase the temperature, lay the bottles on a reflective surface, like a sheet of corrugated iron, and shield them from cooling by the wind.

http://web.mit.edu/watsan/Docs/Student%2...ns2002.pdf

SODIS works best between 35oS and 35o N. Outside of these regions, SODIS works sub-optimally because of the limited availability of solar radiation and the colder climate.

In order to assess the applicability of SODIS to colder climates, this study investigated two possible methods of ensuring that SODIS is effective under the conditions of lower temperatures and sunlight intensity: 1) enhancing the heating capacity of the bottle with black paint and 2) increasing the amount of radiation incident on the system using a solar reflector. Additionally, a mathematical model for predicting the expected bottle water temperature of each exposure regime, based on the ambient air temperature, wind, and available solar radiation, was developed. Such a model will be useful in future studies for assessing which type of exposure regime will be most effective.

Field studies were conducted in two locations in Haiti: Barasa and Dumay, and in Boston, Massachusetts, between the months of January through March, 2002. Analysis of the data collected showed that clear and half-painted bottles were most effective for microbial inactivation in non-tropical climates (Barasa and Boston). In Dumay, however, significant microbial inactivation was achieved in all bottles because the bottle water temperatures reached were much higher. There was no statistical significance between the amount of inactivation achieved by bottle on a reflector or without a reflector.

However, because of the limited amount of data, further studies on the use of solar reflectors are recommended to assess their actual effectiveness...

In order for thermal inactivation alone to be effective for microbial deactivation in the SODIS system, a bottle water temperature of 50o C must be exceeded for at least one hour. Additionally, reaching this temperature also causes synergistic effects between UV and temperature to be enabled. It has been shown that painting the bottom half of the bottles black can raise the water temperature 5o C, depending on the amount of radiation available. In order to test this technique under sub-optimal SODIS conditions, bottles in this study were painted half black so that UV inactivation of bacteria could also take
place within the bottle. Additional bottles were fully painted in hopes of absorbing more radiation than the half painted bottles and thus raising the temperature more.

Under sub-optimal conditions, there was no significant difference in the amount the bottle water temperature was raised in the half-painted or fully painted bottles. The bottle water temperature of the clear bottles was the same as that of the ambient air temperature. In Barasa, the peak temperature difference between the clear and painted bottles was 8o
C ñ greater than that expected from the literature. However, this only achieved a peak bottle water temperature of 38o
C, well below the thresholds mentioned above. In Dumay however, which has similar amounts of available solar radiation, a
temperature difference of almost 10o C was achieved, and the threshold temperature of 50o C was exceeded in both painted bottles. The difference in the peak temperature achieved can be mainly attributed to the difference in weather conditions, which were cooler and breezier in Barasa, which would cause cooler bottle water temperatures.

73 de KE4SKY
In
"Almost Heaven" West Virginia
USA
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21 November 2016, 22:12,
#20
RE: Water Purification Tablets
So really it is the heat that is killing the microbes more than the UV actions.

35s to 35n with water to 50c for one hour counts out most of North America and Europe except in the absolute warmest days of mid summer.

This is absolutely not a method I would want to rely on in my region. I don't think I would rely on it anywhere unless I was short the three twigs or half cup of petrol in a can of sand it would take to boil the water.
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