Performance of Alum & Polyaluminum Chloride as Efficient Coagulants for Fluoride Removal in Batch and Continuous Reactors

Swati Dubey; Madhu Agarwal; Akhilendra Bhushan Gupta; Yogendra Solanki

Authors

Swati Dubey Department of Chemical Engineering, Malaviya National Institute of Technology, Jaipur, India 302017
Madhu Agarwal Department of Chemical Engineering, Malaviya National Institute of Technology, Jaipur, India 302017
Akhilendra Bhushan Gupta Department of Civil Engineering, Malaviya National Institute of Technology, Jaipur, India 302017
Yogendra Solanki Department of Chemical Engineering, Malaviya National Institute of Technology, Jaipur, India 302017

Keywords:

Fluoride, alum, polyaluminum chloride, batch, continuous Nomenclature PACl- Poly aluminum chloride Alum- Aluminum sulphate

Abstract

In this study, performance of alum and polyaluminum chloride(PACl) for fluoride removal has been compared in batch and continuous modes. Experiments were performed to determine the optimum doses of coagulant for bringing the fluoride (<1.5 ppm) and aluminum(0.2 ppm) within acceptable limits. The residual fluoride was found to be higher in case of alum as compared to PACl representing less efficient settling of suspensions, primarily comprise of alumino-fluoro complexes. In addition to this, water treated with PACl contains relatively low soluble salts compared to alum & also requires lesser lime for pH compensation due to its lower acidity. It was also observed that the PACl treated water contains less residual aluminium(0.34ppm) compared to alum (0.46 ppm) when initial fluoride concentration of water was 4 ppm. In batch mode, residual Al was found to be 0.182 ppm (alum) & 0.143 ppm (PACl), after subsequent microfiltration which conform to the Al standards in defluoridated water.