Remediation of fluoride contaminated water using encapsulated active growing blue-green algae, Phormidium sp.

Fluoride is a global water contaminant of geogenic nature impacting human health. Encapsulation of active blue-green algae, Phormidium sp. as biosorbent provides a unique type of biosorbent that continuously develops new active sites for biosorption and can be separated easily from treated water. The experiment was conducted in batch mode with varying parameters - initial pH (3.5-4.5 after an initial screening of wide range pH), initial fluoride concentration (2.0-10.0 mg/L), and different biomass amounts 3.0-6.0 g (biosorbent dose). The parameters mentioned above were considered and optimized using response surface methodology (RSM). Additionally, the biosorption study assures 60% removal from 3.0 mg/L of initial fluoride concentration. Furthermore, the process was found to follow the Freundlich isotherm model. The study follows first-order kinetics; further, the intra-particle diffusion and surface biosorption both contribute to the rate-determining step. In addition to that, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) results also confirmed the contribution of algal biomass towards fluoride removal. (c) 2020 Published by Elsevier B.V.