The removal of chromium (VI) and phenol from industrial waste waters mediated by Acinetobacter haemolyticus

Abstract

Contamination of the environment due to heavy metals and organic waste is a serious problem nowadays. These types of contaminants are toxic and can be dangerous to human health. Heavy metal contaminants include copper, lead and hexavalent chromium while phenol, benzene and toluene are examples of organic pollutants. A treatment of these contaminated waste chemicals must be carried out before they can be released into the environment. Conventional techniques for the treatment of these contaminants are not cost - effective as they are chemical and energy - intensive. Thus, the emerging biological methods for treating these wastes i.e. bioremediation, is more favorable. In this study, a locally isolated bacterium, Acinetobacter haemolyticus was chosen for the removal of Cr (VI) and phenol using batch and column systems. Cr (VI) and phenol removal studies were carried out separately and simultaneously using batch and column systems. When treated separately, about 90% and 95% of Cr (VI) could be removed using the batch and column system, respectively. However, for phenol, 30 - 65% and 50 - 80% of the organic compound could be removed using the batch and column system, respectively. In the simultaneous treatment process, the mixed waste effluent of Cr (VI) and phenol was also treated using the same system. About 70% and 85% of Cr (VI) could be removed in the batch and column system respectively while for phenol, about 30 - 40% was removed using the batch system and 50 - 60% for the column system. The batch system also required a longer retention time compared to the column system. This study has demonstrated the ability of Acinetobacter haemolitycus to remove Cr (VI) and phenol both from separate and mixed effluent, thus offering a promising alternative method for the detoxification of both pollutants prior to releasing the effluent into the environment.