Effective biological treatment of water polluted with coomassie brilliant blue and methylene blue using carbon nanotube‐supported biodegradation

Abstract

This work was designed to improve bacterial biodegradation of coomassie brilliant blue and methylene blue dyes by applying carbon nanotubes to facilitate bacterial cell feeding for dyes biodegradation. A bacterial consortium and azobacter were investigated, and conditions for improved biodegradation were optimized. The methodology included; first stage activation of carbon nanotubes by pretreatment with nitric acid for 6 h, washing, and drying at 105°C. The second stage included optimization of biodegradation conditions, using 20 ml glass tubes containing 12 ml of nutrient broth media inoculated with 1 ml of the bacterial source samples. Coomassie brilliant blue or methylene blue (10 mg L−1) was added to the mixture, and the decolorization efficiency was evaluated over time. For the primary adaptation of the biodegradation process, the removal efficiencies for coomassie brilliant blue were 70.2% and 69.2% when using a sand consortium and azobacter, respectively, and for methylene blue they were 81.0% and 82.6% with a sand consortium and azobacter, respectively. The biodegradation process exhibited maximum efficiency at a temperature of 30°C with shaking at 150 rpm. After applying the carbon nanotubes, the removal efficiencies were improved and those for coomassie brilliant blue were 95% and 93% for the sand consortium and azobacter, respectively, and 96% and 99% for methylene blue with the sand consortium and azobacter, respectively.