The scale-up of Cr3+ biosorption onto olive stone in a fixed bed column

Abstract

In this work, the scale up of olive stone columns for water purification, based on results from the biosorption of Cr(III) onto olive stone in a fixed bed column at pilot scale, was developed. Pilot-scale experiments were carried out in a fixed bed column to test the influence of various parameters (flow rate, bed depth, and initial chromium concentration) on breakthrough curves. Mathematical relationships were developed to describe Cr(III) biosorption in fixed bed column of olive stone at pilot scale. The results were found to be consistent with the previous published results obtained from laboratory scale. The bed depth service time (BDST), the Adams–Bohart, the Thomas, the Yoon and Nelson, and the Dose–Response models were used to analyze the experimental data and the model parameters were evaluated. The BDST allowed comparison between performances of pilot- and laboratory-scale columns, and Dose–Response model showed good agreement of the experimental breakthrough curves with model predictions. The results showed that when the initial Cr(III) concentration was increased from 10 to 80 mg/L, the corresponding biosorption bed capacity increased from 0.126 to 0.262 mg/g at constant flow rate and bed depth. Also, breakthrough time varies from 30 to 220 min when the bed height increases from 21.5 to 62.0 cm at constant flow rate and initial Cr(III) concentration. Results showed that scale up multiplied by nearly 1.7 the important parameters as critical bed depth and length of unused bed (the same relation that the ratio between length/diameter of pilot-scale column and laboratory-scale column).