Abstract

The progress in the technology for wastewater biological treatment has been possible thanks to the advances reached in the knowledge of microbiological, kinetic and stequiometric bases of the processes and thanks to the application of concepts and design methods typical of chemical engineering. The purpose of this work is to study the behaviour of phenolic compounds in an anaerobic-aerobic system. Therefore, an anaerobic reactor UASB and an aerobic reactor of active sludges were operated in a sequential way. The rate of organic charge (VCO) in the anaerobic reactor was increased to study the biodegradation of total phenolic compounds and the colour of that system under reducing and oxidizing conditions. Final results show that there is a part of total phenolic compounds which cannot be degraded and which remains preferably in the molecular weight fraction higher than 10.000 Ca, due to high concentrations of colour in the treated effuent. DQO, tannins and lignins recalcitrant to the anaerobic-aerobic treatment, were determined i the range between 270-350 mg DQO/L and 23-36 mg/L, respectively. Nevertheless, global efficiency of DBO5 removal was higher than 90%.