Bioremediation of Some Reactive Dyes Commonly used in Fabric Re-dyeing by Chlorella vulgaris

Abstract

Aim: The work was aimed at assessing the potential of Chlorella vulgaris in remediation of reactive dyes. Place and Duration of Study: Department of Biological Sciences, Department of Plant Biology and Department of Biochemistry, Bayero University, Kano, Nigeria, between January 2019 and December 2019. Methodology: Wastewater containing individual reactive dyes: reactive red 198 (RR198), reactive yellow 176 (RY176), reactive green 19 (RG19), reactive orange 122 (RO122), reactive red 195 (RR195) and reactive violet 1 (RV1) were collected from a local fabric re-dyeing pit at Kofar Na’isa, Kano, Nigeria. The green microalga C. vulgaris was cultured in Bold Basal medium (BBM) at 30 ± 2°C and subjected to adsorption and decolourization assays of the dyes. Results: The highest dye removal efficiency by enzymatic action was recorded after 48 hours, while that for the biomass adsorption was at day 14, at pH 11.3 and temperature of 30°C. The percentage dye removal by adsorption and decolourization were within the ranges of 68.1-97.8% and 69.8-99.9% respectively. Dye removal decreased with increase in contact time until saturation is attained. Freundlich’s isotherm model was best fitted for the adsorption of the dyes with a strong linear correlation coefficient, R2 ranging from 0.954-0.811. There was a strong linear relationship and high statistical significance among the dyes for both decolourization and adsorption (P value; .01). Conclusion: Chlorella vulgaris was found to be effective in the removal of reactive dyes from textile wastewater samples. The results revealed C. vulgaris to be a cost-effective and eco-friendly biosorbent that can be used for the treatment of wastewaters containing toxic dyes.