The biosorption properties of the Pleurotus mutilus fungal biomass waste collected from an antibiotic production plant to remove Mn+2 and Fe+3 from the ground water were investigated. The residue was characterised by IR analysis. These showed that amino and carboxyl were the main functional groups present in the biosorbent. The structural and morphological characteristics of Pleurotus mutilus fungal biomass were determined by scanning electron microscopic (SEM) analysis. Batch biosorption experiments were performed at different pH to find optimum pH. Langmuir, Freundlich, Redlich-Peterson, Dubinin-Radushkevich (D-R) and Temkin models were applied to describe a single biosorption equilibrium data. The Langmuir model gave the best fit for the data of single component. Maximum biosorption capacities of 26.7 mg Fe+3/g biomass and 18.5 mg Mn+2/g biomass were obtained. HNO3 was selected as desorption agent. 92% of Fe+3 and 95% Mn+2 were obtained after regeneration.