Simultaneous removal of Cr(VI) and phenol from binary solution using Bacillus sp. immobilized onto tea waste biomass

In this investigation, simultaneous Cr(VI) reduction and phenol degradation from contaminated water using Bacillus sp. immobilized onto the surface of tea waste biomass have been studied in a batch reactor. It was observed that Bacillus sp. utilized phenol as a carbon source for Cr(VI) reduction. Optimal conditions were achieved at a biomass dosage of 15 g/L with an initial concentration of 100 mg/L of Cr(VI) and 50 mg/L of phenol. The maximum uptake capacity of Cr(VI) and phenol onto tea waste biomass surface was 741.389 mg/g and 7.761 mg/g, respectively. The equilibrium condition was reached after 27 h for phenol and 48 h for Cr(VI). Multicomponent isotherm models were used to determine the adsorption mechanism for both Cr(VI) reduction and phenol degradation. Non-modified competitive Redlich–Peterson was found to be the best fit for Cr(VI) sorption while extended Langmuir was followed in the case of phenol degradation. Moreover, the experimental results revealed that both Cr(VI) and phenol were well described by the pseudo second-order model.