Arsenic Pollution in water supply networks of Viterbo region, Italy: Geochemical occurrence & Mitigation process

In this study, geological and hydrochemical conditions responsible for elevated concentrations of arsenic were evaluated through the correlation between groundwater chemistry, geology and arsenic concentrations. Besides, the preliminary results of arsenic mitigation process, based on reverse osmosis technology, was discussed. In order to examine the level of the As enrichment and the factors influencing this enrichment in drinking water supply networks of the Province of Viterbo and Rome, Central Italy, water samples were collected from various springs and wells. According to Piper diagram classification, the following hydrochemical facies were identified: (i) Na-HCO3 type water; (ii) Na-Ca-HCO3 (no dominant type); (iii) Ca-HCO3. Arsenic was detected in 241 spring and groundwater samples and 52 % of the total samples show high As concentrations exceeding the WHO maximum contaminant level of 10 µg/L for arsenic in drinking water. The results obtained suggest that most probable As sources in groundwater are related to natural processes such as lithology, mineralogy and local hydrogeology. According to the preliminary on-site treatment system, it was concluded that practical processes can be developed with reverse osmosis to remove major species (As(III) and As(V)) of arsenic from water.