Bioprecipitation of Strontium by Sulphate Reducing Bacteria
Authors: Ngwenya, N.; Chirwa, E. M. N.
Source: Proceedings of the Water Environment Federation, WEFTEC 2008: Session 61 through Session 70 , pp. 4850-4863(14)
Publisher: Water Environment Federation
Abstract:This study investigates the sorption of Sr2+ from aqueous solution by a growing sulphate reducing bacteria consortium. The kinetics of strontium sorption by sulphate reducing bacteria at different initial strontium concentrations (25, 50 and 75 mg L-1), different sulphate reducing bacteria biomass types (dead, growing and resting) as well as different sorbent doses (0.5, 1.0, 2.0, and 3g L-1) were fitted into the Lagergren pseudo-first and second order, and the intraparticle diffusion model. The distribution of the bioprecipitated solid phase strontium species was determined by the application of a five-step sequential extraction procedure. Results obtained showed that strontium sorption by sulphate reducing bacteria follows a second-order process, where chemisorption is the main rate-controlling step. Strontium sorption increased with increasing initial concentration, further suggesting that removal occurred through passive processes, such as biosorption and chemical precipitation. Results obtained from the sequential leaching procedure indicated that about 68% of the removed strontium was adsorbed on the surface of the bacteria by relatively weak electrostatic interaction, while about 22% was bound to carbonates, 4% bound to oxides, 3% bound to sulphides and remainder occurring as an immobile fraction, further supporting model predictions of chemisorption as the main mechanism of strontium uptake.
Document Type: Research article
Publication date: 2008-01-01
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