Village organisations become development partners

Village organisations become development partner

SORAS - a simple arsenic removal process

The serious threat to the health of millions of people through consumption of arsenic-rich groundwater in Bangladesh calls for immediate action on various levels. One of these actions is be the development of a low-cost and simple arsenic removal method available to every household. The development of alternative water sources and/or the installation of larger arsenic removal units will take more time due to logistic and financial constraints. Currently existing small-scale arsenic removal procedures require chemicals that are either not easily available and/or affect water taste and odour. Solar oxidation and removal of arsenic (SORAS) is a simple method that uses irradiation of water with sunlight in PET- or other UV-A transparent bottles to reduce arsenic levels from drinking water. The SORAS method is based on photochemical oxidation of As(III) followed by precipitation or filtration of As(V) adsorbed on Fe(III)oxides as shown in Fig. 1. Groundwater in Bangladesh naturally contains Fe(II) and Fe(III) and therefore, SORAS could reduce arsenic contents and would be available to everyone at virtually no cost. It could be a water treatment method used at household level to treat small quantities of drinking water

SODIS - an arsenic mitigation option?

About 95% of the population in Bangladesh is supplied by groundwater from five million wells. Several survey programmes revealed that arsenic might be found in three million wells affecting up to 70 million people. Currently, alternative water resources and water treatment processes for the arsenic removal are being developed. One considered option is to return from the groundwater to surface water which, however, in most cases is not safe for consumption and, therefore, requires disinfection. SODIS (Solar Water Disinfection) is a simple and lowcost water treatment method to improve the microbiological quality of drinking water at household level. PET plastic bottles are filled with polluted water and exposed to sunlight for 1 day. The microorgansisms are inactivated by the UV-A radiation and the increased water temperature. SODIS applied world-wide is described in www.sodis.ch and has been field tested in Bangladesh to study its effciency and socio-cultural acceptance