Impact of phosphate, silicate and natural organic matter on the size of FE(III) precipitates and arsenate co-precipitation efficiency in calcium containing water

“Removal of arsenic (As) from water by co-precipitation with Fe(III) (oxyhydr)oxides is a widely used technique in water treatment. Nevertheless, As removal efficiency appears to be sensitive to the composition of the water matrix. The aim of this study was to gain a deeper understanding of the independent and combined effects of silicate (Si), phosphate (P), natural organic matter (NOM) and calcium (Ca) on arsenate [As(V)] co-precipitation efficiency and the size of Fe(III) precipitates. We found that, in complex solutions, containing multiple solutes and high levels of Ca, (variations in) Si and P concentrations reduce As(V) removal to some extent, mainly due to a decreased adsorption of As(V) onto Fe(III) precipitates. On the other hand, NOM concentrations reduced As(V) removal to a much greater extent, due to possible formation of mobile Fe(III)–NOM complexes that were difficult to remove by filtration. These findings have a great significance for predicting As(V) removal as a function of seasonal and process-related water quality changes at water treatment plants.”

© 2019 The Authors. Published by Elsevier B.V. – Under a Creative Commons CC-BY-NC-ND license

(Citaat: Ahmad, A., Rutten, S., Eikelboom, M., de Waal, L., et al. – Impact of phosphate, silicate and natural organic matter on the size of FE(III) precipitates and arsenate co-precipitation efficiency in calcium containing water – Separation and Purification Technology 235(2020)116117 – DOI: 10.1016/j.seppur.2019.116117 – (Open Access))