Colour removal from simulated dye wastewaters by electrochemical treatment

Dye wastewaters can be treated by biological, chemical and electrochemical methods. An electrochemical approach refers to the electrogeneration of metal hydroxides floes that adsorb dyes and produce decolourisation. The main objective of this paper was to assess the colour removal from simulated wastewaters containing direct (Direct Red 4A) and fibre reactive (Reactive Red M3A, Reactive Orange MG and Reactive Blue 4) dyes by aluminium based coagulant generated in an electrochemical cell with horizontal electrodes. Prior to water treatment experiments, the involvement of dyes in the development of electrode processes was pointed out by plotting polarization curves in various conditions. The extent of dyes involvement in electrode processes was riot a decisive factor for the subsequent water treatment. The colour removal efficiency depended on dye nature (89% for direct red, about 70% for reactive orange and reactive red and 94% for reactive blue) and occurred mainly in the bulk of solution.