Community-based defluoridation of groundwater by electrocoagulation followed by activated alumina adsorption

Abstract

Water is essential to human life, yet over billion people across the world have no access to safe drinking water. It is evident in the report of WHO that there is an excess fluoride concentration in groundwater of more than 25 countries including developed and developing countries across the world. Widespread fluorosis cases related to the presence of fluoride in groundwater supplies are major public health problems. Electrocoagulation is an emerging technology for fluoride removal. Activated alumina is a common adsorbent for fluoride removal. In this study, electrocoagulation along with sand filtration was tried as a pretreatment followed by activated alumina adsorption. This technology has been installed in Chhoto Irga village of Purulia district of West Bengal. The results show that electrocoagulation can remove fluoride to a significant extent. Provision of activated alumina bed helps to take care of fluoride removal in case of the electrocoagulation setup malfunctions. Electrocoagulation removes a significant amount of fluoride, and therefore, the challenge to the subsequent alumina bed is reduced helping to prolong the life of alumina bed before exhaustion. In this design, the alumina bed is split into two columns-lead and lag. It helps to utilize more adsorption capacity of alumina and also allows for a time before regeneration of an exhausted alumina column can be actually performed without jeopardizing the safety of the treated water. The aluminum concentration was found to be below permissible limit in the drinking water. The community-based and self-sustained defluoridation unit is functioning till date.