Biosorption of Cr(III) ions from tannery wastewater by Pleurotus ostreatus

The article extends the study on the removal of Cr(III) ions by utilizing Basidiomycetous fungus viz., Pleurotus ostreatus (Jacq.) Quélet from aqueous solution. To predict the biosorption performance of the test fungus with actual wastewater of tannery, laboratory assays were conducted with synthetic pure metal-bearing solutions. Oven dried biomass of test fungus was utilized to evaluate the effect of pH, stirring intensity and initial metal ion concentrations. Results revealed optimum pH 4.5, stirring intensity 150 rpm, with increase in removal rate on increasing metal ion concentrations (4-20 mgL-1) in the medium. The Langmuir and Freundlich models use to check the distribution of metallic ions between liquid and solid phase adequately described all experimental data on sorption capacity of the test fungus. On exposure of fungal biomass in tannery effluents 55% of biosorption efficiency for Cr(III) ions was obtained. To amplify this potential for prospective commercialization of biotechnology through the test fungus, the production of fungus was carried out on the economically cheaper substrates viz., rice straw, wheat straw and cotton waste. The results clearly indicated among the agro-wastes (colonized) best removal efficiency was recorded for wheat straw (80-90%). Due to the low cost involved and simplicity of the technique, wheat straw colonized with P. ostreatus could be utilized as an excellent biosorbent for removal of Cr(III) ions from tannery wastewater containing low concentration of the metal.