Aplicação de campo magnético em reator tubular com recirculação de biomassa na remoção biológica de cromo (VI)

Abstract

The accelerated process of industrialization has contributed much to environmental pollution and water contamination by toxic substances such as chromium, and is currently a big problem, so the search for new methods of treatment for the effluent. This study aimed to evaluate the behavior of a mixed culture under the action of a magnetic field in the treatment of wastewater contaminated with hexavalent chromium. The mixed culture used was already present in the laboratory of Biochemical Engineering, School of Chemical Engineering in UFU, being cultivated and kept cool. The magnetic field was generated by an electric current flowing through a conductor and produces a magnetic field around the conductor, taking the same behavior of a magnet. The magnetic field produced was pulsed, with square wave of constant intensity and frequency. A treatment system was constructed, consisting of a stirred tank reactor with constant mechanical stirring, coupled with a tubular reactor where the effluent was pumped in the presence of the magnetic field. The mixed culture has not gone through the process of adaptation to high concentrations of hexavalent chromium. The chromium (VI) removal by mixed culture applying the field in different frequencies (2, 5 and 10 Hz), with an initial concentration of chromium (VI) 150 mg/L were evaluated. Evaluated was the first use of the cells, followed by the first and second cell reuses. With the second reuse cells, it was evaluated the cell replacement by new cells in two different quantities of one and two thirds of inoculum. The best results were obtained with application of the field 5 Hz, removing 100% of total chromium and hexavalent all of the effluent after 2 hours of the experiment, no reduction was observed in the state of oxidation of Cr and biodegradation of organic matter remained above 86,71%. The reuse of the cells was also studied at different initial concentrations of chromium (80, 120 and 150 mg/L) with application of the field 5 Hz. The removal of total chromium to the first use and first reuse of the cells remained above 96% and 93%, respectively, at all concentrations, however the second reuse removal was over 90% for the concentration of 80 and 120 mg/L and 62,60% for 150 mg/L.