Sistema automatizado para desfluoretação de águas subterrâneas.

Abstract

The high concentration of fluoride in drinking water is identified as the cause of a condition called dental fluorosis, characterized by stains on the teeth, particularly affecting children. This substance occurs naturally and is commonly found in deep wells, which are widely used as an alternative water supply for small, usually isolated communities that have difficulty accessing the public water supply networks provided by sanitation companies. Despite the availability of individual water treatment systems (at point of use), the current challenge is the development of economically viable water treatment system for collective use. To remove the excess fluoride ions from the water, an automated system for groundwater defluoridation was developed and installed in a metal container that can be easily adapted to the existing water network. This station has a maximum flow rate of 5,000 L h-1 , which is sufficient to serve a community of up to 500 people, and utilizes the contact precipitation mechanism for fluoride removal by adding calcium and phosphorus salts to an adsorbent medium of bonechar. The use of automation components such as control valves and automatic reagent dosing reduces the need for on-site human intervention and consequently enhances the economic viability of the system, especially for isolated communities. A full-scale pilot unit was installed in a community in the municipality of Cachoeira do Sul, Rio Grande do Sul, demonstrating fluoride levels suitable for human consumption, around 0.64 mg L-1 , without significantly altering other water quality parameters.