Decolourisation Process of Drimaren Blue CL-BR by Using Aspergillus oryzae Biomass and the Toxicity Assessment of the Final Product

Dyes have wide range of applications in the textile printing, leather and paper dyeing, food colouring, pharmaceutical and cosmetic industries. Dyes containing wastewaters originated from these industries results in the pollution of aquatic ecosystems such as lakes and rivers. Decolourisation of these dyes by using physical and chemical methods such as adsorption, oxidation, coagulation-flocculation, chemical degradation and photo-degradation also produce toxic and carcinogenic dye-derivatives. But biological decolourisation of dyes is more economic and ecologically friendly than other methods. In this study, the effects of various conditions such as initial pH, dye concentrations, glucose and yeast extract concentrations; temperature and agitation on decolourising activity of Aspergillus oryzae were investigated. These were all found to be important for Drimaren Blue CL-BR decolourising activity of A. oryzae. The decolourisation of the dye involved adsorption and absorption of the dye compound by A. oryzae pellet at the initial stage, followed by the decolourisation through fungal metabolism. The maximum decolourisation rate of the dye was determined as 94.4% under optimum conditions. The toxicity of Drimaren Blue CL-BR at 300 mg/L and 15.3 mg/L concentrations was also tested by analysis of DNA damage as measured by comet assay in peripheral erythrocytes of Carassius aurotus exposed to the dye for 48 hours.