Abstract:
There is a significant increase in industrial activities due to the increasing population and demand. Textile and dye industries are also important groups of these industrial fields. In these fields, high amounts of dyes are used. After dyeing process, 10-15% of dyes are discharged into wastewaters. Existence of dyes in wastewaters is an undesired condition because they cause lots of diseases on living beings and also various problems on aquatic and terrestrial environments. Because disperse dyes do not show ionization in aquatic environments, they generally tend to bioaccumulation. Conventional biological wastewater treatment systems are not efficient for color removal of dyes. In this study, bacterial decolorization, which is an environmentally friendly and effective method, was investigated. For this aim, a thermophilic (Bacillus firmus) and a mesophilic bacterium (Bacillus subtilis) were tested in the color removal of various Foron textile dyes, a group of disperse dyes, such as Foron Brown (FB), Foron Black (FBL), Foron Turquoise (FT), Foron Violet (FV) and Foron Red (FR). The tested dyes (200 mg/L) were incubated with Bacillus species under the shaking condition for 24 h at various temperatures. Colors of all the dyes were efficiently removed by both bacterial species at the end of 24 h of incubation. The highest color removal rates of FB, FBL, FT, FV and FR treated with B. firmus were about 63, 87, 56, 77 and 74%, respectively. The maximum decolorization percentages of the same dyes incubated with B. subtilis were determined as 69, 80, 55, 73 and 59%, respectively.
