A Wickeramomyces anomalus biofilm supported on wood husk was used to remediate water bodies contaminated with chromium (Cr), in batch and open systems. The favorable adhesion ability of the chromium-resistant yeast strain on the wood husk was predicted by XDLVO theory and confirmed by environmental scanning electronic microscopy. The chromium decontamination was then optimized in a batch mode using a central composite design (CCD). Analysis of variance (ANOVA) showed a high coefficient of determination (R2) value of 0.93-0.91 for Cr(VI) and total Cr removal, respectively, ensuring a satisfactory fitting of the second-order regression model to the experimental data. In batch system, the concentration of biomass exhibited the minimal effect on the process. An acidic pH of 3.72 and 5.48, an initial chromium concentration of 10 and 16.91 mg/L and a support dose of 6.95 and 8.20 g/L were optimal for Cr(VI) and total Cr removal, respectively. The breakthrough curves were determined in open system for different initial chromium concentrations. The study of glucose concentration effect on the yeast extracellular polymeric substances (EPS) production showed that a medium exempt of glucose allowed maximal EPS production and minimal chromium removal efficiency, while 20 g/L glucose concentration of presented the optimal condition for chromium removal.
Keywords: Biofilm; Biosorption; Chromium; Wood husk; Yeast.
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