Interference of a magnetic field generated by circular magnets in the retention of chromium by microbial cells and in the morphology of a mixed culture during the bio-removal of chromium from effluent

A magnetic field of 5 Hz and magnetic field intensities of 15.9 and 57.8 m T, generated by 40 circular magnets, was investigated with the objective of influencing mixed culture in the removal of chromium and total organic carbon (TOC) from an effluent contaminated with Cr(VI) and verifying the effects on mixed culture morphology and the retention of chromium by microbial cells during the treatment process. For the magnetic field time of 7 h and 48 min, the removal of Cr(VI), total Cr, and TOC corresponded to 99.97 +/- 0.01, 74.2 +/- 1.2, and 25.1 +/- 1.5 %, respectively. This was higher than results obtained when the bioreactor was operated without a magnetic field for the evaluated time. The amount of chromium retained in the cells by the experiments with and without magnetic fields was 0.59 and 0.53 %, respectively, justifying one of the mechanisms that increase the removal. The morphology of the mixed culture did not show changes in the images from scanning electron microscopy with the presence of chromium or the magnetic field.