Efficacy of Acinetobacter sp. B9 for simultaneous removal of phenol and hexavalent chromium from co-contaminated system.

The present study shows the feasibility of a newly isolated strain Acinetobacter sp. B9 for concurrent removal of phenol and Cr (VI) from wastewater. The experiments were conducted in a batch reactor under aerobic conditions. Initially, when mineral salt solution was used as the culture medium, the strain was found to utilize phenol as sole carbon and energy source while no Cr (VI) removal was observed. However, the addition of glucose as co-carbon source resulted in the removal of both toxicants. This co-removal efficiency of the strain was further improved with nutrient-rich media (NB). Optimum co-removal was determined at 188 mg L(-1) of phenol and 3.5 mg L(-1) of Cr (VI) concentrations at pH 7.0. Strain B9 followed the orthometabolic pathway for phenol degradation. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) studies showed sorption of chromium as one of the major mechanisms for Cr (VI) removal by B9 cells. Acinetobacter sp. B9 was later on checked for bioremediation of real tannery wastewater. After 96 h of batch treatment of tannery effluent containing an initial 47 mg L(-1) phenol and 16 mg L(-1) Cr (VI), complete removal of phenol and 87 % reduction of Cr (VI) were attained, showing high efficiency of the bacterial strain for potential application in industrial pollution control.