Diseño de sistemas de biodegradación aerobia y anaerobia a escala piloto para la descontaminación de aceites dieléctricos con bifenilos policlorados (PCB’s)

Abstract

The present work was carried out in order to determine the degree of aerobic and anaerobic biodegradation of dielectric oils contaminated with PCB´s. The used strains of microorganisms were able to degrade chlorinated compounds, the type of bacteria that presented greater affinity with the pollutants was the B350. Initially, a bacterial inoculant was prepared to verify the suitability of the microorganisms versus the concentrations of 700 and 2 000 ppm of PCB's, afterwards the bacterial growth was built and this phase ended with the reproductive stage. Six biorreactors were studied at pilot scale, three anaerobes that degraded the dielectric oil with a concentration of 700 ppm of PCB’s during 15 weeks, and three anaerobes degraded dielectric oil with 2 000 ppm of PCB’s within a period of 20 weeks, each one operated with different conditions of pH between 6,2 and 6,8; aeration between 60 and 70 (cm3/min), rate of feed on the basis of methanol between 0,20 to 0,30 (g/L/day) and agitation. To determine the reduction of polychlorinated biphenyls, tests were conducted every three weeks by gas chromatography. The aerobic process with best results was the biorreactor 2 with 15,41% of degradation, which operated at a pH of 6,8 with aeration of 70 (cm3/min) and without agitation. With regard to the anaerobic systems, the biorreactor 1 provided the best results with 8,02% of degradation, and operated at a pH of 6,2 with loading rate on the basis of methanol 0,20 (g/L/day).