I used to work as a WASH coordinator in a community and do regular well disinfection to prevent potential cholera outbreaks and other waterborne diseases.
We train community health workers in doing so through calculations and measures which is never easy.
Could anyone suggest a reliable, simple and practical technology or method for less educated staff to maintain well disinfection in a region threatened constantly by cholera outbreak?
Joe Cotruvo answered the dose requirement and chlorine sources that can be used. However, the application depends on the system. Is this a well that pumps water to a large storage tank? Is this a manual well that people pump the water from themselves? The application will determine the appropriate technique. For a well that feeds a large tank, the simplest method is a venturi injection system. When the well comes on the dose is consistent as long as there is a chlorine supply (tablet feeder, chlorine bleach tank, on-site generator, etc.). If individuals are manually treating the water and have their own source of chlorine, then they need the appropriate measuring devices for bleach or chlorine tablets, etc. Of course I am biased here, but we sell an individual or family sized 4 oz. (108 g) small hand held electrochlorinator that operates from the on-board solar panel or USB port. 300 liters treated per charge and the device has 1, 2, 5, 10, and 20 liter settings. The device (H2gO Purifier) automatically produces the appropriate dose (2.5 mg/L) for the volume selected. No measuring required. Simple to use. lasts 10 years. Built to military specs. www.aquaresearchllc.com.
the poor generally store their the drinking water in a simple filter container made of aluminium. if they filter it through a double cotton cloth & keep a copper ring permanently in the filter vessel overnight it will kill the bacteria & make it fit for drinking & cooking.
It does not require very much chlorine, but it must be continuous. As you well know there are numerous easy to manage methods, that vary by cost and availability in some areas. The simplest is sodium hypochlorite (laundry bleach) that can be purchased or produced on site by electrolysis of salt solution, including solar source electricity. I once saw a bicycle operated electricity generator. Since it is a liquid, it is easy to meter in at a continuous rate. Calcium hypochlorite is stable and available, but a solid. Chlorinated isocyanurates that are often used for swimming pool disinfection, are also stable solids that can also be used for drinking water-see WHO Guidelines. The isocyanurates are probably costly by comparison to NaOCl, but more stable. Keep in mind that the concentration x time (CT) determines the minimum dosage. For chlorine at pH 6 to 9 and at 10C, you can get 3 logs of virus removal with 1 mg/l for 4 minutes contact time. Less chlorine is need at warmer temperatures and longer contact times.
What about chlorine dioxide? A small chlorine dioxide generator associated with a well would do the job without the dangers of the standard old chlorine treatment.
A few years ago WEDC, at Loughborough University, published some guidance on this. I suggest that you have a look at their Knowledge Base on their web site.