Knowledge sharing
Henk Holtslag - Sunday 21 May 2006LS
I see some interesting information in the last days and would like to share some more.
1. Testing water quality, Ecoli
To get an indication of water quality we often use Pathoscreen P/A pillows. The 100 ml of tested water turns black and stinks if the ecoli contents is to high so a good visible way of showing quality of water. Cost are around 1 US$ per test and is a HACH product. see websites of Hach.
2. Comparison of HWTS options
At the SODIS/ HWTS meeting in november 2005 in Quito Tom Clasen presented an interesting study comparing sevaral HWTS options. In this test Ceramic filters were most effective maybe also because they are more attractive than other options?. There are Ceramic filters with candle, disc or potshaped filtering elements but the bottem line is that the combination of ceramic and a few cnest of colloidal silver makes clean water (regarding turbidity and harmfull bacteria), With innovation cost of ceramic filters are still reducing so we see this as very promising. Next month we will start some pilots with the vacuum candel filters (Zambia Mozambique and Tanzania, mentioned before by Klaas van der Ven.
3. Colloidal silver
For impregnating ceramic Pot shaped filters ( potter for peace model) in Ghana and El Salvador, Colloildal silver in powder form is used, obtained from ARGONOL in Spain. The advantage of the powder is the easy low cost trasport.
1 kg for 7000 filters!. Cost of treament with this options is around 7 Cents US per filter element.
4. Bubble test for candle filters
Tests of candle filters from India and Brazil indicated that many candles have leaks between the ceramic part and the plastic or metal cap. A simple way to test this is the "Bubble test". Connect a piece of hose to the nipple , immerse the candle in water and blow. If big bubbles come out directly, the candle is not fit for use.
So far some information
I would like to thank Susan for the good back ground paper and the organisers for this opportunity.
Success al of you and go on sharing knowledge until all have safe water.
Henk Holtslag
www.practicafoundation.nl