ARSENIC REMOVAL FROM WATER BY PHYSICO-CHEMICAL METHODS

Abstract

A laboratory investigation was carried out to study the removal of arsenic by adsorption from water samples containing arsenic of known concentrations, using iron oxidecont and uncoated river sand of 0.50 mm geometric mean size, as adsorbents. Methods for removing arsenic from water include adsorption-coprecipitation with hydrolyzing metals, such as aluminium or iron (III), adsorption on activated alumina or activated carbon, ion-exchange and reverse osmosis, coagulation etc. All the methods available for removing arsenic, are costly and not applicable at a large scale in the field. The present study of removal of arsenic from water by iron-oxide coated sand was under taken with a view to provide low cost solution to the drinking water having arsenic problem which would be feasible in term of village level .application. Batch studies were carried out by varying the following parameters : 1. Dose of adsorbent. 2. Initial pH of arsenic solution. 3. Initial arsenic concentration. 4. Contact time. Column studies were carried out by varying the following parameters : 1. Initial arsenic concentration. 2. Initial pH of arsenic solution. 3. Bed depths of medium (adsorbent). 4. Filtration rates. Arsenic removal of 94% by coated sand and 40% by uncoated sand has been observed at optimum dose and initial concentration 1 mg/1 of arsenic.