Selective biosorption of precious metals by cell-surface engineered microalgae

Abstract

Biosorptive recovery of precious metals (PMs) has gained attention in industry due to its potential low cost, high efficiency and environmentally compatibility. This study aims to use highly selective engineered microalgae species as biosorbents for recovery of PMs. Microalgae proliferate in both freshwater and marine environments unlike macroalgae found at coast lines. Microalgae have showed great potential as biosorbents owing to their high binding affinity, low nutrient requirements and local availability. Previous research was undertaken by sourcing microalgae from a eutrophic dam in Hartbeespoort, South Africa. The results from tested microalgae showed a relatively higher sorption capacity for lanthanum (La), thallium (Tl) and cadmium (Cd). Among the microalga sorbents, the self-flocculating microalgae have the ability to aggregate together and form flocs, which can facilitate their gravity sedimentation for biomass recovery. This technology offers a more cost-effective and energy-saving method than conventional separation methods such as centrifugation and filtration. This study attempts to combine the cell-surface engineering with the self-flocculating microalga sorbents, which would be a high efficient potential method to selective biosorption of target PM from multimetal solutions.