Removal of fluoride from drinking water to permissible levels with Bajra husk

Abstract

Water is an essential natural resource, required for the survival and maintenance of life on earth. Though the blue planet consists of 71 % of water, only 0.03 % is usable by humans. With the advent of many climatic, geological, and anthropogenic activities, the freshwater content on earth has been constantly polluted, making it unfit for consumption and posing health issues. The rise in demand for freshwater has made the aquifers and groundwater vulnerable to excessive drilling and excavation, which has resulted in the surfacing of geologic and environmental contaminants in groundwater. Fluoride is one such groundwater contaminant whose excessive intake leads to health complications in humans, such as dental, skeletal, and non-skeletal fluorosis. Fluorosis is incurable and prevention is the only solution to this menace. Currently practiced techniques of defluoridation like reverse osmosis, nanofiltration, coagulation and precipitation, adsorption, solar distillation, electrocoagulation, electrodialysis, and ion exchange are highly expensive and their difficult operation is making them unsuitable and inaccessible by all sections of the society. Adsorption-based techniques are suitable, effective, and cost inexpensive among them. The use of bioadsorbents is found to be advantageous over chemical adsorbents due to their natural origin, renewability, easy availability, biodegradability, and low cost. Using the different agriculture wastes as bioadsorbents for effective defluoridation may help in waste management and water remediation. Owing to the above context, the present research aims to prospect the husk of Bajra crop as a bioadsorbent material for effective defluoridation. Biochar prepared by Bajra husk showed a maximum of ∼ 99 % fluoride removal. At pH value 2 the highest defluoridation was achieved. The present findings revealed that using agricultural waste of Bajra crops for the preparation of value-added products in the form of bioadsorbent for fluoride removal will help in waste management and also in the defluoridation of water.