Research Note pubs.acs.org/IECR
Biosorption and Recovery of Chromium from Industrial Wastewaters By Using Saccharomyces cerevisiae in a Flow-Through System Giovanni Colica, Pier Cesare Mecarozzi, and Roberto De Philippis* Department of Agricultural Biotechnology, University of Florence, Piazzale delle Cascine 24, I 50144 Firenze, Italy ABSTRACT: This study investigated the possibility to adsorb and recycle Cr(VI) from the wastewater of a Cr-electroplating process using Saccharomyces cerevisiae in a flow-through system at a pilot scale. In a first set of experiments, it was demonstrated that an HCl pretreatment of the biomass induced a 2-fold increase in the amount of Cr(VI) removed. In the following experiments, 30 L of wastewater was treated with HCl-pretreated yeast biomass confined in a filter press, obtaining an average specific metal removal of 13 mg per g of dry biomass. At the end of the bioremoval process, the biomass was incinerated and the ashes thus obtained were composed of >90% (w/w) chromium. The results obtained at pilot scale with chromium-containing wastewaters demonstrated the good metal sorption capability of the acid-pretreated S. cerevisiae biomass and the possibility to recover, at a high purity, the metal from the biomass at the end of the treatment process.
1. INTRODUCTION For many years, Saccharomyces cerevisiae has been considered to be a promising biosorbent for industrial applications, because of some unique characteristics: (i) the process for its production at high substrate/biomass conversion yields is well-established at the industrial level; (ii) biomass of S. cerevisiae can be obtained at low cost as a byproduct derived from various food and beverage fermentation industries;1 (iii) S. cerevisiae is classified as a GRAS (Generally Recognized As Safe) product and, therefore, its use as biosorbent can be easily accepted by the public when utilized in water-treating industrial plants. S. cerevisiae has been extensively studied utilizing various approaches,1 e.g., by comparing the performances of living and dead cells,2 or that of immobilized and free cells;3 nevertheless, there are still several issues that require more-detailed investigations before this biosorbent can be exploited in industrial wastewater treatment processes. This study was aimed at assessing, using a flow-through pilot device, the possibility to use dry yeast biomass for the removal and the recovery of Cr(VI) from wastewaters deriving from a chromium plating industry. In particular, this research was aimed at selecting the best biosorbent among three commercial baker’s yeasts and determining the best pretreatment (rehydration with water or sucrose solution, autoclaving, acid treatment) for the biomass to be used in the chromium bioremoval. This study was also aimed at assessing the performances of the best yeast strain in a pilot flow-through system, designed for being easily utilized as the final refining stage in a conventional treating plant, and at recovering the sorbed metal from the biomass in order to reuse it in industrial processes.
stored for the following use. The lyophilized biomass was utilized in the experiments with or without an acid pretreatment (see below). 2.2. Industrial Cr(VI)-Containing Wastewater Utilized. Industrial wastewater, derived from a chromium plating process and containing Cr(VI) at a concentration of 55.3 g L−1 at pH 1.46, was utilized to prepare the solutions for the experiments. The metal composition of the wastewater, determined by inductively coupled plasma−-mass spectrometry (ICP-MS), was as follows: Cr(VI), 89.71% (w/w); Cr(III), 8.97%; other elements, 1.32% (Zn, 0.52%; Cu, 0.40%; Ni, 0.33%; Fe, 0.05%; Pb, 0.02%; Cd,
