Treatment of Water by Tamarugite Produced from White Aluminium Dross

Abstract

Aluminium dross is an industrial hazardous by-product obtained in aluminium smelter plants in large quantities. Dross when subjected to water bodies decreases the groundwater pH and presence of leachable salts like NaCl and KCl in dross increases the environmental crisis (Meshram and Singh, 2018). Usually white dross has adequate metallic aluminium content that is extracted through existing pyrometallurgical and hydrometallurgical routes. Even though dross may be recycled using these technologies, large quantities of dross remains end up being land filled. This research work emphasizes on synthesis of an inorganic coagulant, tamarugite, by utilizing the aluminium content entrapped in the dross. Application of tamarugite, being a rare mineral, has not been thoroughly examined but the authors have observed the use of manufactured mineral as a coagulant in water treatment (Meshram et al. 2019).

In this work, white aluminium dross is subjected to leaching with concentrated sulphuric acid. Analysis of aluminium content was being done by EDTA-EBT back titrations. Subsequently equimolar sodium hydroxide solution is added to the filtrate obtained after leaching. This solution is heated to saturation. As a solvent ethanol is employed to precipitate hydrophilic molecules of tamarugite from the saturated solution. The precipitate is decanted, washed with methanol and stored in desiccator is characterized with respect to phase, elemental, microstructural and thermal analysis. Authors have studied its coagulation potential for various types of water under different ranges of pH. Obtained sludge has been examined using EDS to understand further about the heavy metal removal. Comparison between tamarugite and various commercial coagulants has been done by Jar test. Therefore, a unique method of treating water from an industrial waste is proposed that connects solid waste management and water treatment. Development of number of such valuable products from various waste materials is an exciting aspect of industrial waste management engineering, which is the crux of sustainable development.

Keywords: Tamarugite; Aluminium dross; Organic solvent precipitation; Recycling; Waste management