Removal of inorganic As5+ from a small drinking water system

The drinking water from a small drinking water system contained arsenic in a concentration of about 50 mu g/L. Chemical analyses showed that the pentavalent form of arsenic was present. Since the MCL value is 10 mu g/L, it was necessary to implement a technological treatment to make the water suitable for drinking. In order to do so, two technologies were suggested: activated alumina and alpha-FeOOH (TehnoArz, TA) adsorption media. Experiments using both adsorption media were performed on a laboratory scale. It was possible to remove arsenic to below 1 mu g/L. The maximal adsorption capacity was found to be 12.7 mg of As5+ per gram of alpha-FeOOH. Moreover, all the important physico-chemical parameters of the water remained practically unchanged after the treatment. Only a slight release of iron from the media was observed. The Fe-As bond was studied by means of chemical analysis and X-ray powder diffraction. Finally, in addition to showing the capability of arsenic removal by alpha-FeOOH, a comprehensive optimization of the technological parameters of the selected technology is provided.