Removal of arsenic from underground water to obtain drinking water [articol]

Abstract

Scientists found excessive arsenic concentrations is several underground waters in the world. In these areas, hundreds of thousands of people presented serious intoxications due to this element. Billions of people, especially in developing countries, use daily water with an arsenic content several times higher than the limit of 10 ppb, recommended by the World Health Organization. The main method for the removal of arsenic from water is the physical-chemical treatment. In the present paper is investigated the possibility to remove arsenic from underground water with high arsenic content using filtration on sand filter. Water samples have been collected from wells in an area with high arsenic content. The analyses showed that in some of the samples the concentrations of iron, manganese and arsenic were higher than the maximum values permitted by the legislation. The studies on arsenic removal were carried out on a synthetic solution with a composition similar to the studied waters. This solution has been aerated then passed over a sand layer in order to retain iron, manganese and arsenic. The residual concentrations of iron, manganese and arsenic in the effluent were under the detection limit. We concluded that the insoluble iron compounds resulting during aeration and retained on sand present high adsorption capacity for arsenic. Underground waters with high arsenic content which also contain iron ions can be used as drinking waters after a simple pass on a sand layer.