Congo Red Dye Biosorption Using Bacillus cereus MW13 Isolated from the Wastewater of a Mulberry Paper Mill

Abstract

The untreated Congo red discharge from the textile and paper industries has several impacts on humans, including carcinogenic and mutagenic effects, as well as on aquatic life and the environment. The current study investigated the biosorption performance of dye-tolerant bacteria for the removal of Congo red under various factors. B. cereus MW13 was isolated from the wastewater of a mulberry paper mill in Northern Thailand. The optimum conditions were a Congo red initial concentration of 600 mg/L, a biomass concentration of 4 g/L, and a contact time of 240 min, resulting in the maximum removal efficiency of 90.24±0.11%. The highest biosorption capacity, 367.52±8.93 mg/g, was achieved at a biomass concentration of 0.5 g/L. The biosorption isotherm and kinetic analysis were best fit by the Langmuir model (R²=0.9852) and the pseudo-second-order model (R²=0.9916), respectively. SEM and TEM analyses showed that Congo red molecules appeared on the cell surface and inside the bacterial cells. Furthermore, the functional groups of B. cereus MW13 after Congo red exposure, including the hydroxyl, amino, and carboxyl groups, as well as the S=O stretching of the Congo red molecule, were detected by FTIR analysis. It revealed that a chemical reaction occurred during the biosorption process. These results confirmed the potential of B. cereus MW13 biomass for Congo red bioremediation.