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Mickey Sampson - Monday 22 May 2006Variety of items: Mickey Sampson
I am the country director for Resource Development International – Cambodia. I have been working in water and sanitation implementation in Cambodia for over 8 years now. RDIC has a water research laboratory in Cambodia and has been involved in evaluating and implementation of various HWT methods including ceramic filters, UV systems, SODIS. www.rdic.org
Silver: I would like to add a few notes to Reid and others work in using silver as a biocide. For those of you who are just beginning to explore this field please read information on Argyia a pigment discoloration which can result from ingestion of silver. I say this not to dissuade you from using it but you should know about this condition. Also Reid brings up using AgCl which is the product of silver nitrate with table salt. If you remember back to your general chemistry class you learn that AgCl is insoluble. Unfortunately if you look further into the book you discover that when studying Ksp (equilibrium) AgCl is in fact soluble but in relatively low concentrations. Therefore if you are using AgCl in treatment of storage containers small amounts of Ag+ are being released gradually. Not necessarily a bad thing and it may play a key role in the disinfection mechanism, but it means your coating will have a limited life span. We have experimented with the powder colloidal silver mentioned by Henk and treated traditional clay water jars in Cambodia. We found that they effectively eliminate e. coli for 7-9 months in jars which were left standing at room temperature for 12-18 hours. Reid also mentioned using thermal reduction (silver nitrate is heated driving off the nitrate leaving silver metal) as a potential process. We have also done a similar thing using a chemical reducing agent. We have used vitamin C which is of course harmless to reduce the Ag+ to silver metal. There are of course a wide range of other compounds which can be used in a similar way.
Failures: One of my greatest failures was in the introduction of UV system into villages and homes approximately 8 year ago. Although, the technology was strong I failed to understand the key educational issues as well as culture issues. Villagers preferred to use the car batteries, designed to run the UV lamp, to operate their TVs and lights at night. Most never understood the purpose of the UV lamp and often times failed to turn it on. This process while painful for me was incredibly educational. I learned the importance of culture and education as well as a new golden rule technology alone is not the solution if it were the world would have clean drinking water. At this point we began to explore new methods of education these have developed over the years and now include such things as KARAOKE education. Karaoke is a great fun way to sing about health issues and teach villagers in an entertaining way. Because of cultural, economic status and different water sources we now employ various methods of HWT this reinforces the concept that there is not a single silver bullet, but we must use a variety of approaches to be effective.
Monitoring and evaluation: I strongly agree with Susan there is a great need to come up with a set of standards. These standards will allow us to more clearly understand the roles of technology, education and acceptance (cultural). I also would like to add evaluation from outside your own organization can be very valuable. It is easy to have bias towards the technology you are implementing. RDI has a ceramic filter factory (20,000 plus pot style filters will be sold this year) and we have been fortunate enough to have Joe Brown a graduate student from Dr. Mark Sobsey group from University of North Carolina to do an assessment of our filters in the field. This study is more extensive than most, and the information has been very useful and has strengthened my desire to increase our efforts in education and improve some of our existing monitoring methods. This study should be available to others early next month.
Ceramic filters: Currently our ceramic filters sell for $7 and replacement ceramic inserts are $2.50. At this price we believe that the filters will be sustainable over the long term. Currently sales are making a modest profit which we are putting back into the program in the form of subsidies for poor families. At this point NGOs are still our largest market, but that is slowly being shifted into retail sales. I strongly urge those of you who are looking at various technologies to take a strong look at the ceramic options.
E coli testing: I would like to recommend a product called easy-gel Coliscan the company who produces it is called micrology labs. We experimented with this product and compared it to standard membrane technology used in our lab with outstanding results. We also use it in the field at ambient temperatures in Cambodia. The technology uses a chromogenic media (meaning at the end different bacteria colonies take on different colors). This method can be used to quantify concentrations of e. coli and total coliform cost is only about $1.35 per test and is very simple to use. Simply add 5 ml of your sample to a premixed media, then pour the media into a special Petri dish and allow it to set for 24 hours and you can then read count your colonies and calculate your cfu values.
I would like to thank to organizers of e-conference. I believe it has been beneficial to all who have participated.