Hydrodynamic effects on the performance of electro-coagulation/electro-flotation for the removal of dyes from textile wastewater

The paper describes a study on the electro-coagulation/electro-flotation of textile wastewater bearing a mixture of three disperse dyes. The experiments were performed in a stirred reactor that was equipped with an aluminum sacrificial anode (100 cm(2)) and a stainless-steel cathode. Decolorization occurred in two well-distinguishable phases: a destabilization of colloids in the reactions with coagulating compounds formed in situ during anode dissolution (volumetric coagulation), and a subsequent gas flotation of particle agglomerates. Both phases proved to be dependent on the hydrodynamic conditions in the reactor and the applied current density. Model equations are derived from experimental data for the kinetics of the single phases of the process, for mechanical stirring and agitation by pumping.