Optimization of production of extracellular polymeric substances byArthrobacter viscosusand their interaction with a 13X zeolite for the biosorption of Cr(VI)

Abstract

In this work we aimed to optimize the production of extracellular polymeric substances (EPS) by an Arthrobacter viscosus biofilm supported on 13X zeolite to be used in the biosorption of Cr(VI). The optimization parameters were agitation rate, work volume, pH and glucose concentration. Following the optimization of EPS production, the biofilm was used in the biosorption of hexavalent Cr from liquid solutions. Differences between the use of dead or active biomass and between the performance of zeolite in powder or in pellet form were also studied. The optimized EPS production allowed values of metal uptake between 2.72 mg/g(biosorbent) and 7.88 mg/g(biosorbent) for initial Cr(VI) concentrations of 20-60 mg/L. For an initial concentration of 20 mg/L, the optimal conditions of EPS production allowed an increase of 10% on the removal percentage of total Cr, and the use of zeolite as a powder rather than the pelleted form produced an increase of 46.5% in the removal percentage. For the initial concentration of 60 mg/L, the use of active biomass compared to dried biomass allowed a reduction of the time required for the total removal of Cr(VI) from 20 to 13 days.

Bio-reduction of Cr(VI) by exopolysaccharides (EPS) from indigenous bacterial species of Sukinda chromite mine, India

“…The vital role of EPS along with the cell in the adsorption and reduction of chromium has been noted recently (Ozturk et al 2009;Sheng et al 2010;Quintelas et al 2011). A detailed study on bio-removal of chromium by indigenous bacterial isolates from tannery polluted places has also been reported (Sundar et al 2011).…”

Tailored zeolites for the removal of metal oxyanions: Overcoming intrinsic limitations of zeolites

“…The concept of combining bacterial capacity for biosorption of heavy metals with a zeolitic support was originally proposed by Neves and Tavares. The Arthrobacter viscosus bacterium supported on zeolites was extensively used for the treatment of Cr(VI) solutions, and several zeolites were succesfully employed as support (natural clinoptilolite or synthetic FAU, MFI, MOR and BEA zeolites) [24,40,[136][137][138][139][140][141][142][143]. This bacterium is able to form a biofilm on the zeolitic surface, as reported by Lameiras et al The authors found that the removal percentages obtained for the biofilm-laden zeolite sorbent are similar than those previously obtained using instead granular activated carbon (GAC) as support [144].…”

Vermiculite bio-barriers for Cu and Zn remediation: an eco-friendly approach for freshwater and sediments protection

“…LB medium favors the growth of P. putida in batch, but probably it does not allow the production of exopolysaccharides molecules (EPS) on the vermiculite particles, which are crucial substances contributing to bind significant amounts of heavy metals (Pal and Paul 2008;Gadd 2009). Many authors, in fact, confirm that EPS production by several bacteria species normally increase according to their nutrients starvation and environmental stress conditions (Sutherland 2001;González et al 2010;Fang et al 2011;Quintelas et al 2011). …”

“…Natural clays (e.g., vermiculite) have been studied as suitable low-cost materials to be used for wastewater treatment or as permeable barrier in landfills to avoid pollutants release Quintelas et al 2011;Malamis and Katsou 2013). The tetra-and octahedral structure of phyllosilicates, in fact, favors a high surface area and a high availability of negative charges.…”