Title: Removal of mineral scaling precursors from electrodialysis concentrate by alkaline precipitation

Authors: Emily Mayer Andrade Becheleni; Edward Michael Peters; Ricardo Perobelli Borba; Sônia Denise Ferreira Rocha

Addresses: Institute of Engineering, Science and Technology, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Avenida Um, 4.050 – Cidade Universitária, Janaúba – Minas Gerais, 39447-814, Brazil ' Chemical Engineering Department, KTH Royal Institute of Technology, SE-100 44, Stockholm, Sweden ' Geology and Natural Resource Department, Universidade Estadual de Campinas, Rua João Pandiá Calógeras, 51. Campinas, São Paulo,13083-870, Brazil ' Department of Mining Engineering, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, 6627, Pampulha, Belo Horizonte – Minas Gerais, 31270-901, Brazil

Abstract: Evaporative crystallisation has been used to recover water for industrial reuse but it presents serious problems related to incrustation. In this perspective, alkaline precipitation is studied in the present work, aiming to remove scale-forming salts prior to evaporative crystallisation of a reverse electrodialysis concentrate (EDC). The concentration of inorganic species in the feed and filtrate streams were determined by ICP-OES. The total organic carbon and inorganic carbon were analysed by thermo-catalytic oxidation with high temperature to assess the removal of organic compounds from EDC. The software PHREEQC was used to model the systems and a comparison with experimental results confirmed the credibility of the experiments. The technique proved to be a favourable method for removal of almost 100% of Ca and Mg by adding 0.04 wt. % of caustic soda. Furthermore, this would improve the downstream evaporative crystallisation efficiency due to reduced incrustation potential.

Keywords: PHREEQC; desalination; calcium carbonate; magnesium hydroxide; reverse electrodialysis; scaling; hydrogeochemical model; precipitation; water reuse; demineralisation process.

DOI: 10.1504/IJEWM.2023.129732

International Journal of Environment and Waste Management, 2023 Vol.31 No.1, pp.19 - 41

Received: 23 Jan 2020
Accepted: 12 Jul 2020
Published online: 22 Mar 2023 *