Simultaneous bioremediation of Cr(VI) and phenol from single and binary solution using Bacillus sp.: Multicomponent kinetic modeling

In the present study, batch experiments for simultaneous biological degradation of phenol and bioaccumulation of Cr(VI) by a bacterial strain Bacillus sp. (MTCC No. 3166) were carried out in incubator cum shaker at 30 °C and 120 rpm. The Bacillus sp. was acclimatized to the various concentrations of Cr(VI) and phenol both in single and binary substrate solution. This bacterium can reduce the toxic concentration of Cr(VI) up to 25 mg/L and phenol was degraded up to 50 mg/L. In a binary substrate solution of Cr(VI) and phenol (1:2 ratio), reduction of Cr(VI) was found more than a single substrate solution at all concentrations of Cr(VI). The possible reason behind this fact that Bacillus sp. was utilized phenol as carbon source for the reduction of Cr(VI). Monod and Haldane kinetics models are used to explain the kinetics of Cr(VI) reduction and Phenol degradation. The interaction parameter of Cr(VI) was more than of phenol, which shows that Cr(VI) inhibited the effect of both reduction of Cr(VI) and biodegradation of while phenol improves the Cr(VI) reduction kinetic. Yield coefficient and the decay coefficient after the exponential phase of the bacterium were estimated, for Cr(VI) and phenol both in single and binary substrate solution.