How to Pasteurize Water with a Plastic Bottle

How To Pasteurize Water with a Plastic Bottle?

Short Description

• Problem: fighting diarrhea and water transmitted diseases
• Idea: Using the combined action of UVA radiations and of pasteurization temperature buy putting rather clear water in a transparent bottle in the sun for a day.
• Difficulty: Only for small amounts. Doesn't treat chemical polution. Doesn't change the colour, the odor or the taste of the water. clean storage and quick use once opened.
• Price Range: cheap
• Material Needed: transparent plastic bottles with their cap. (black paint)
• Geographic Area: Sunny areas best.
• Competencies: none
• How Many people? one person
• How Long does it take? 20 min the first time + laying in the sun time ( between 6 hours and 2 days)

Description

SODIS is cheap and practical water treatment method which uses solar energy to improve the microbiological water quality. It is used at household level to treat small quantities fo drinking water. SODIS was developed by the EAWAG Institute in Switzerland and is promoted by SANDEC. SODIS is ideal to treat small quantities of water. Contaminated water is filled into transparent plastic bottles and exposed to full sunlight for six hours. The water has to be relatively transparent ( low turbidity). If it is not the case, you should filter the water first till it is possible to read the Sodis Logo through the bottle. . To pre-filter the water, see for exemple How to Lower Water Turbidity with a Roughing Filter?

Fill the bottle 3/4 and shake it to let more oxygen dissolve in the water. This ameliorates the UV action. Then fill the bottle completely and lay it in the sun. Best is if you can lay it on a dark surface orientated to the sun, or even paint half of the bottle black, and present the transparent part to the sun.

Difficulties

Only for small amounts. Doesn't treat chemical polution. Doesn't change the colour, the odor or the taste of the water. Clean storage and quick use once opened.

Links

www.sandec.ch www.sodis.ch

Categories:

Technique

What is SODIS?

A treatment method to eliminate the pathogens which cause water-borne diseases Ideal to disinfect small quantities of water used for consumption A water treatment process depending on solar energy only An alternative water treatment option for use mainly at household level An old but so far hardly applied water purification method

SODIS does not

change the chemical water quality change the odour nor the taste of the water increase the water quantity or reduce water shortages Limitations of SODIS

SODIS is not useful to treat large volumes of water SODIS requires relativly clear water (turbidity less than 30 NTU) SODIS needs solar radiation (exposure time 6 hours under bright or up to 50% cloudy sky, or 2 consecutive days unter 100% cloudy sky)

Sunlight is treating the contaminated water through two synergetic mechanisms: Radiation in the spectrum of UV-A (wavelength 320-400nm) and increased water temperature. If the water temperatures raises above 50°C, the disinfection process is three times faster.