3.5. Cr(III) chemical flocculation
In spite of the success obtained for the bacterial growth of all the
strains in the presence of Cr(VI) and the high percentages of concentration
decrease of this ion in the analyzed cultures, the Cr(III)
produced by the reduction remains in solution. For the biotreatment
to be complete, the total precipitation of Cr(III) has to be
achieved. The final pH was theoretically adequate for the formation
of the hydroxide but due to the extremely low concentration
of the cation, this process is not detected in the isolated supernatants
of the cultures. Different precipitation agents were studied
using standard solutions of Cr(III), resulting the sodium carbonate
solution the most effective one considering not only the amount