Family filter with iron-coated sand: solution for arsenic removal in rural areas

Abstract

The presence of arsenic in groundwater is recognised as a threat to public health world-wide and specifically in rural areas of several developing countries due to variety of health-related problems observed in populations ingesting arsenic-containing water. Several arsenic removal technologies suitable mainly for centralised treatment are available or under investigation. However, point-of-use arsenic removal systems, suitable for application at household level appear to be the only feasible solution under conditions prevailing in rural areas of developing countries characterised in general by the absence of centralised water supply systems. Several household level arsenic removal units are commercially available and some of them are currently under testing in Bangladesh. Nevertheless there is still need to develop a more efficient and sustainable point-of-use arsenic removal unit. Very promising results were recently obtained in laboratory experiments with a simple “family filter” with iron-coated sand (ICS) or iron-impregnated granular activated carbon. The objective of this study was to establish methodology for assessment and selection of appropriate ICS for arsenic removal with “family filter”. An additional objective was to optimise and test further “family filter” with selected ICS. Batch and filtration laboratory adsorption experiments were conducted with five types of ICS originating from Dutch groundwater treatment plants and model and natural groundwater with high arsenic concentration. All ICSs tested demonstrated arsenic removal potential with removal efficiencies ranging from 50 to 100%. Short adsorption experiments can be applied to screen the suitability of different ICSs. Adsorption isotherm and filter runs are, however, needed to establish arsenic adsorption capacity of a particular ICS. Contact time was found to be the critical parameter for “family filter” design and performance. The “family filter”, very simple point-of-use treatment unit, equipped with an appropriate ICS demonstrated high arsenic removal potential and could be very attractive for arsenic removal in rural areas of developing countries.