AbstractColored industrial effluents have become a vital source of water pollution, and because water is the most important natural source; its treatment is a responsibility. Usually colored wastewater is treated by physical and chemical processes. But these technologies are ineffective in removing dyes, expensive and not adaptable to a wide range of colored water. Biosorption was identified as the preferred technique for bleaching colored wastewater by giving the best results.This treatment was based on the use of dead fungal biomass as new material for treating industrial colored effluents by biosorption. We studied the ability of biosorption of methylene blue (MB) by Aspergillus fumigatus and optimize the conditions for better absorption.Biosorption reaches 68% at 120 min. Similarly, the biosorbed amount increases up to 65% with pH from 4 to 6, and it's similar and around 90% for pH from 7 to 13. At ambient temperature 20-22°C, the percentage of biosorption of methylene blue was optimal. The kinetic of biosorption is directly related to the surface of biosorbent when the particle size is also an important factor affecting the ability of biosorption. Also the biosorption of methylene blue increases with the dose of biosorbent due to an augmentation of the adsorption surface.In this study, for an initial concentration of 12 mg/L of MB (biosorbent/solution ratio=2g/L) buffered to alkaline pH, and a contact time of 120 min, biosorption takes place at an ambient temperature and reaches 93.5% under these conditions.