RESUMO
Hexavalent chromium (Cr VI) from industrial wastewaters represents a highly toxic source at low concentrations. Biological treatments with anaerobic granular biomass are a promising alternative for the Cr VI bioremediation. This study evaluated the Cr VI removal in a range of 5-500â¯mg/L, using an active anaerobic granular consortium. Two removal mechanisms were differentiated from the assays: 1) biological reduction of 70â¯mg/L to Cr III at a concentration of 250â¯mg Cr VI/L and 2) physical bioadsorption of 297â¯mg of Cr VI/L or 31.39â¯mg of Cr VI/gbiomass at concentration of 500â¯mg Cr VI /L. The half-maximal inhibitory concentration (IC50) values for the rate and production of methane were 1.4 and 253â¯mg/L, respectively. In addition, Cr VI is a biostimulant that increase the methane production, in a range from 5 to 100â¯mg/L, of the anaerobic consortium. This work demonstrates the potential application of the anaerobic granular consortium in metal bioremediation.