Abstract: A method of removing cations from water and a process arrangement for performing the method, wherein the method includes containing cations selected from a group consisting of Se, As, Sb, Cr, Mn, Mo, W, V, Te, P, Si including preparing an iron precipitate-containing sludge by electrochemical water treatment, wherein the water is led through an electrochemical water treatment unit, wherein electricity dissolves iron from an anode to the water thereby forming an iron precipitate-containing sludge to which cations to be removed are adsorbed/co-precipitated, adsorption and co-precipitation enhancing to provide a very high density sludge having an iron precipitate concentration of 50-400 g/l thereby further adsorbing cations contained in the water, and separating solids from the obtained sludge thereby producing treated water having a reduced cation content and solids comprising iron precipitate compounds and adsorbed/co-precipitated cation compounds.

Abstract: A method of removing cations from water and a process arrangement for performing the method, wherein the method includes containing cations selected from a group consisting of Se, As, Sb, Cr, Mn, Mo, W, V, Te, P, Si including preparing an iron precipitate-containing sludge by electrochemical water treatment, wherein the water is led through an electrochemical water treatment unit, wherein electricity dissolves iron from an anode to the water thereby forming an iron precipitate-containing sludge to which cations to be removed are adsorbed/co-precipitated, adsorption and co-precipitation enhancing to provide a very high density sludge having an iron precipitate concentration of 50-400 g/l thereby further adsorbing cations contained in the water, and separating solids from the obtained sludge thereby producing treated water having a reduced cation content and solids comprising iron precipitate compounds and adsorbed/co-precipitated cation compounds.