Evaluacion in vitro de la capacidad de una cepa nativa del genero Bacillus sp para remover el cromo presente en los vertimientos de la curtiembre José Abel Maz ( B. San Benito , Bogotá DC - Colombia )

Abstract

The ability of native strain of Bacillus subtilis extracted from the tannery Jose Abel Maz effluents; to transform Cr (VI) to Cr (III) in a batch system was evaluated. In in vitro tests, it reached an effectiveness of 95.84% under aerobic conditions, constant temperature and neutral pH. A prototype for the treatment system, composed by two tanks, one for microbiological treatment (batch reactor) and other chemical treatment was built. 3 tests were performed in the reactor, reaching an average of 87.052% reduction of Cr (VI) by the inoculation with Bacillus subtilis. The relationship between bacterial growth and the decrease in the concentration of Cr (VI) was demonstrated. In the second tank, a complementary treatment was carried out in order to reduce the levels of Cr (III); this was achieved by chemical precipitation using a strong base (Sodium Hydroxide). A volume of 27.20% of Chromium Hydroxide was obtained; this could be used in a subsequent step to recover Chrome tanning salts. In the supernatant of the precipitate, the levels of Cr (III) were reduced 99.89% on average. In all three trials, the permissible levels of Cr (VI) and Cr(III) met the current regulations.