COD removal from actual industrial wastewater using a three-dimensional electrochemical apparatus

Chemical oxygen demand (COD) removal was investigated using a three-dimensional electrochemical system. The effects of electrode position, pH value, initial temperature, circulation flow, aeration, and addition of hydrogen peroxide on the removal efficiency of the pollutant were studied. The fillers used in the experiment were centimetre-sized and electrolyte was obtained from an industrial factory with a concentration of COD as high as 25 000-27 500 mg L-1, which was rare in other studies of the past. The degradation of organics was affected by pH and circulation flow, and a decrease in the initial pH value led to the increase in removal efficiency, while a trend of increasing at first and then decreasing was observed with the extension of circulation flow. Aeration and hydrogen peroxide served as enhanced processes for a higher removal rate. Both ultrasound and ultraviolet had effects on the electrolysis system. Oxygen uptake rate measurement and bio-treatment experiments demonstrated a significant increase in biodegradability with this three-dimensional electrochemical system. In addition, a pilot scale test in a pharmaceutical factory showed an economic benefit on energy consumption, which was as low as 10 kWh kg(-1) COD.