Removal of fluoride from an industrial wastewater by a hybrid process combining precipitation and reverse osmosis

Abstract

The purpose of this study is to apply a hybrid process that combines the precipitation with hydrate lime along with reverse osmosis (RO) treatment to deal with a real industrial wastewater having an excessive fluoride concentration of 3,200 mg/L. The effluent is discharged from an aluminum fluoride manufacturing unit. Neutralization with hydrated lime using excesses above 50% at pH 7–8 led to fluoride removal rates higher than 98%. The industrial effluent neutralized under optimal conditions underwent an RO treatment that allowed to reduce the fluoride content to about 8 mg/L giving an overall removal of 99.9% F⁻. This study demonstrated that the hybrid precipitation–RO process could effectively remove fluoride from wastewater, and produce permeate and precipitates for potential recovery and reuse.

Keywords:

• Aluminum fluoride manufacturing
• Industrial wastewater
• Fluoride removal
• Precipitation
• Reverse osmosis

Notes

Presented at the Conference on Desalination for the Environment: Clean Water and Energy 11–15 May 2014, Limassol, Cyprus