Comparative analysis for three different immobilisation strategies in the hexavalent chromium biosorption process using Bacillus sphaericus S-layer

Abstract

Hexavalent chromium constitutes an important water pollutant due to its cancerogenic properties. In countries such as Colombia it is widely used as a preservative in the leather industry. Bacillus sphaericus S-layer exhibits high metal-binding capacity hence the use of this microorganism to remove metals such as chromium from polluted regions based on immobilised cells systems is suggested to be an interesting proposal. The paper describes thermodynamic adsorption process of Cr(VI) on immobilised biomass of B. sphaericus cells on polyurethane foam, sol-gel, and sawdust. The adsorption isotherms describe different immobilisation mechanisms regarding the support utilised. For example, polyurethane and sawdust immobilisation process were described with the classical Langmuir model while sol-gel followed Generalised Freundlich-Kiselev behaviour. Moreover, through determining breakthrough curves in packed columns with each medium we found surface diffusion and mass bulk transfer rate as crucial factors when scaling-up the process. © 2011 Canadian Society for Chemical Engineering.