Reducing Cr 6+ in electroplating wastewater with Bacillus cereus strain B 1

Abstract

In this study Bacillus cereus was used to evaluate the Cr 6+ reducing capacity in electroplating effluents. TheCr 6+ bioreduction assays were carried out using real waste water (RWW) from an electroplating plant and artificial wastewater (AWW), with and without added glucose. The AWW was prepared using Ni, Zn, Cu, Pb, and Cr salts, simulating RWW concentrations. The Cr 6+ concentration and bacterial growth were monitored three times a day for the duration of five days. Also, were evaluated the effects of wastewater on B. cereus B 1 morphology using scanning electron microscopy. Cr 6+ reduction percentage of 100 % was reached for AWW containing glucose, of 71 % for AWW without glucose, of 75.6 % for RWW with glucose, and of 31.7 % for RWW without glucose. Despite the low reduction percentage obtained for RWW without glucose, concentrations of 0.14 mg/L of Cr 6+ were reached, which were within allowed limits (0.5mg/L of Cr 6+ ). Electron Microscopy showed alterations in the bacterial cell wall and a decrease in size, mainly in the bacteria exposed to RWW. The results allow us to propose B. cereus B 1 as a promising microorganism for use in the bioremediation of effluents containing Cr 6+ .