Advanced treatment of effluents originated from pharmaceutical industry by electrochemical processes and/or photo catalysis

Abstract

The project aimed at using electrochemical processes and photocatalysis for the advanced treatment of effluents originated from pharmaceutical industry and also those from municipal wastewater treatment plants. The pollutants taken into consideration as models belonged to the active pharmaceutical compounds with aromatic rings in their structure (refractory organic compounds) such as antiinflammatory drugs (ibuprofen, diclofenac, naproxen and piroxicam). The anode materials used for the electrochemical oxidation were DSA based on noble and non-noble metal oxide films and also boron doped diamond (BDD). TiO2 supported on zeolite was the material used for degrading by photocatalysis. The process was controlled by using UV-VIS absorption spectroscopy, high performance liquid chromatography (HPLC) with UV detection and gas chromatography coupled with mass spectroscopy (GC-MS). In order to decay the studied pollutants the following processes were used: electrochemical oxidation, zeolite-supported TiO2 mediated photocatalysis and photocatalytically-assisted electrochemical degradation. The project led to a technology for the advanced treatment of pharmaceutical effluents containing refractory organic compounds based on the best results for inducing biodegradability. By using electrochemical methods with stirring, photocatalytically-assisted electrochemical methods with stirring and combined photocatalyticalelectrochemical methods with stirring, CBO5/CCO-Cr ratio increased from 0.05 to 0.2-0.4 or even higher than 0.4 in the case of pharmaceutical effluents with diclofenac. Electrochemical oxidation at DSA demonstrated to be efficient also for the advanced degradation of complex mixture of micro-pollutants such as nonsteroidal anti-inflammatory drugs in the effluents discharged from municipal wastewater treatment plants