Fluoride Polluted Groundwaters in Calabria Region (Southern Italy): Natural Source and Remediation

• Main Authors: Ilaria Fuoco, Carmine Apollaro, Alessandra Criscuoli, Rosanna De Rosa, Svetlozar Velizarov, Alberto Figoli
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Water
• Subjects: nanofiltration; fluoride; polluted groundwaters; fluorite mineralization
• Online Access: https://www.mdpi.com/2073-4441/13/12/1626

Excessive ingestion of fluoride through the consumption of F⁻-rich drinking water could cause adverse effects to human health. For this reason, the WHO has fixed 1.5 mg/L as the maximum F- concentration for drinking water. In this work, a detailed geochemical characterization was performed to define the source of natural pollution of two groundwaters (samples Pc and Bg) coming from deep crystalline aquifers located in the Calabria region (southern Italy) and to define and optimize the most appropriate water treatment strategy. The samples were classified as a F⁻ enriched NaHCO₃ type of water. In particular, the F⁻ concentrations observed were 30 mg/L and 8.9 mg/L for the Pc and Bg samples, respectively. Based on the acquired geochemical characterization knowledge, the groundwaters were treated by two thin-film composite NF membranes, namely SPR 10113 and SPR 10114 which have so far not been used for water defluoridation. It was found that the SPR 10114 membrane was able to guarantee water permeates with F⁻ contents lower than the threshold value of 1.5 mg/L for both treated waters, whereas the fluoride content remained above the threshold value when the Pc sample was treated using the SPR 10113 membrane. The obtained permeates were characterized by a low ionic load and were not suitable for long-term consumption as drinking water. However, all of the produced waters did not need any further re-mineralizing processes for agricultural irrigation or other purposes.