BDD anodic oxidation as tertiary wastewater treatment for the removal of emerging micro-pollutants, pathogens and organicmatter

This work reports for the first time the removal of 17 alpha-ethynylestradiol (EE2), a synthetic estrogen hormone, from secondary treated effluents by electrochemical oxidation. Experiments were conducted in a single compartment reactor comprising a boron-doped diamond (BDD) anode and a zirconium cathode. EE2, in the range 100-800 mu g L-1, was spiked in the post-chlorination effluent of a municipal treatment plant and oxidized at 0.9-2.6mA cm(-2) current density. Complete degradation of 100 mu g L-1 EE2 was achieved in 7 min at 2.1 mA cm(-2) and inherent conditions, while the addition of 0.1 mol L-1 NaCl achieved removal in just a few seconds. The process was then tested in the pre-chlorination effluent at 2.1 mA cm(-2) and inherent conditions; complete E. coli killing and EE2 removal occurred in just 1.5 and 3.5 min, respectively, while overall estrogenicity (assessed by the YES assay) and residual organic matter (in terms of chemical oxygen demand (COD)) decreased by 50% and 85% after 30 min, respectively. These results clearly show the potential of BBD electrochemical oxidation to serve as an efficient tertiary wastewater treatment. (C) 2011 Society of Chemical Industry