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Membrane Water Treatment Volume 11, Number 4, July 2020 , pages 303-312 DOI: https://doi.org/10.12989/mwt.2020.11.4.303 |
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Hybrid neutralization and membrane process for fluoride removal from an industrial effluent |
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Nouha Meftah, Abdessalem Ezzeddine, Ahmed Bedoui and Ahmed Hannachi
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| Abstract | ||
| This study aims to investigate at a laboratory scale fluorides removal from an industrial wastewater having excessive F- concentration through a hybrid process combining neutralization and membrane separation. For the membrane separation operation, both Reverse Osmosis (RO) and Nanofiltration (NF) were investigated and confronted. The optimized neutralization step with hydrated lime allowed reaching fluoride removal rates of 99.1 ± 0.4 %. To simulate continuous process, consecutive batch treatments with full recirculation of membrane process brines were conducted. Despite the relatively high super saturations with respect to CaF2, no membrane cloaking was observed. The RO polishing treatment allowed decreasing the permeate fluoride concentration to 0.9 ± 0.3 mg/L with a fluoride rejection rate of 93± 2% at the optimal transmembrane pressure of around 100 psi. When NF membrane was used to treat neutralization filtrate, the permeate fluoride concentration dropped to 1.1± 0.4 mg/L with a fluoride rejection rate of 88± 5% at the optimal pressure of around 80 psi. Thus, with respect to RO, NF allowed roughly 20% decrease of the driving pressure at the expense of only 5% drop of rejection rate. Both NF and RO permeates at optimal operating transmembrane pressures respect environmental regulations for reject streams discharge into the environment. | ||
| Key Words | ||
| industrial wastewater; fluoride removal; hybrid treatment process; neutralization; reverse osmosis; nanofiltration; optimization | ||
| Address | ||
| Nouha Meftah, Abdessalem Ezzeddine and Ahmed Hannachi: University of Gabes, National Engineering School of Gabes, Chemical Process Engineering Department, Process Engineering and Industrial System Research Laboratory, Omar Ibn El khattab Street, 6029 Zrig, Gabes, Tunisia Nouha Meftah, Ahmed Bedoui: University of Gabes, Faculty of Sciences of Gabes, Department of Chemistry, Erriadh City, 6072 Zrig, Gabes Tunisia | ||
