| ArticleName |
Wastewater purification from fluorine using iron and aluminium compounds |
| Abstract |
The work is aimed at deep purification of wastewater containing high concentrations of fluorine (F–) up to maximum permissible concentrations of fluorine in drinking and fishery water. The possibility of wastewater purification from fluoride ions by iron or aluminum compounds is described. The studies were carried out on model solutions containing 10 mg/l fluorine. Aluminum compounds are more preferable for deep water purification from fluorine to the maximum permissible concentrations of drinking and fishery water reservoirs. The best results are obtained using aluminum chloride. Secondary contamination with the components of the used reagents does not exceed the maximum permissible concentrations. The method was tested during cleaning of the real sewage of Lovozero GOK, with an average annual fluoride ion content 8.2 mg/l. Thus, at a molar ratio Al3+:F– = 3.5, the residual content of fluoride ions in the solution was 0.72 mg/l, which does not exceed the norms for fishery basins (0.75 mg/l). At the same time, secondary contamination with chloride ions does not exceed the norms for fishery basins, and pollution with aluminum does not exceed the norms for drinking-water reservoirs. A schematic diagram for wastewater purification from an impurity of fluorine (F–) was developed on the basis of the obtained data. It provides the introduction of predetermined amounts of AlCl3 or AlCl3·6H2O in wastewater, adjusting the pH value of the solution to 6–6.5, settling and subsequent processing the resulting fluorine-containing precipitate of aluminum hydroxide. The proposed method is suitable for the purification of large volumes of wastewater from fluoride ions, requiring the minimal capital investment, eliminating the unacceptable secondary contamination effluents with reagents, providing the recycling and regeneration of the fluorine evolved main parts used for effluent reactant cleaning. |
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