ABSTRACT
118The performance of a fixed-bed column packed with coconut shell for the biosorption of Cu(II) ions was evaluated using column breakthrough data at different flow rates, bed-depths and initial Cu(II) concentrations. The Bed Depth Service Time (BDST), Yoon-Nelson, Thomas and Clark models were used to evaluate the characteristic design parameters of the column. The Cu(II) biosorption column had the best performance at 10 mg L-1 inlet Cu(II) concentration, 10 mL min-1 flow rate and 20 cm bed depth. Under these optimum conditions, the service time to breakthrough was about 60 h, after which the Cu(II) concentration in the effluent exceeded the 1 mg L-1 discharge limit set by the Ghana Environmental Protection Agency (EPA). The equilibrium uptake of Cu(II) amounted to 7.25 mg g-1, which is 14.5 times higher than the value obtained in a batch study with the same material for the same initial Cu(II) concentration (10 mg L-1). The BDST model fitted well the experimental data in the 10% and 50% regions of the breakthrough curve. The Yoon-Nelson model predicted well the time required for 50% breakthrough (τ) at all conditions examined. The simulation of the whole breakthrough curve was successful with the Yoon-Nelson model, but the breakthrough curve was best predicted by the Clark model. The design of a fixed bed column for Cu(II) removal from wastewater by biosorption onto coconut shell can be done based on these models.
