Copper contaminated wastewater – An evaluation of bioremedial options

Abstract

The potential of papaya leaf powder and paddy straw powder for copper(II) removal was evaluated from aqueous solution via column and batch adsorption studies. Batch adsorption studies were performed to determine the contact time effects, biosorbent dosage, pH and initial concentration of metal ion on adsorption capacity. Results showed approximately 90% to 95% of copper removal using both the adsorbents from the solution. As the amount of biosorbent increases, the biosorption capacity also increases. Findings indicate that pH is an important factor for metal ion biosorption and 7.0 is the optimum pH for copper removal. For explaining the mechanism of copper distribution into the solid and liquid phases in batch studies, Freundlich isotherm and Langmuir adsorption isotherm model are used and findings illustrate that adsorption phenomenon is better represented by Freundlich isotherm. Maximum adsorption capacity of copper was calculated as 24.63 mg/g and 37.17 mg/g for papaya powder and for paddy straw powder, respectively, by using Langmuir model. The adsorption phenomenon complies with the pseudo-second-order rate equation. Using packed bed column, the biosorbents’ ability of copper(II) ions removal from aqueous solution was also examined and an S shape profile was obtained for the breakthrough curve. For practical applications, both the adsorbents can be effectively used for wastewater treatment owing to their high capacity of adsorption of heavy metals at very low cost.