For bioethanol production, enzymes are required which can be obtained after solid state fermentation and submerged fermentation of cellulosic biomass. After enzyme production, huge biomass is generated as a waste which can be used as an adsorbent. In the study, water hyacinth biomass left after enzyme production using solid state fermentation with the help of fungus Emericella nidulans was used as biosorbent. Firstly different dyes i.e. methylene blue, congo red, malachite green, reactive orange, reactive blue, reactive red and orange G were screened out. After screening, it was found that congo red was maximum decolorized, followed by malachite green and methylene blue. Percent decolorization was 83.7, 82.1 and 80.2 for congo red, malachite green and methylene blue respectively. Different process parameters were optimized using one factor one time and box behnken design of response surface methodology approach. Temperature 30° C and pH 5 was found to be optimum for congo red decolorization. Optimized parameters were adsorbent dose 0.1g, initial dye concentration 177 ppm and contact time 17h outcomes of the box behnken design.
