Evaluation of Cr(VI) Reducing Capability of Shewanella putrefaciens (MTTC8410) and Optimization of Operational Parameters

Annadurai Sakthi Thesai,Ramachandran Palanivelan,Rajalingam Sangeetha,Sundaram Rajakumar,Lakshmanan Ashokkumar,Pudukadu Munusamy Ayyasamy

doi:10.22207/jpam.14.4.49

Abstract

Bioremediation is an important technology to remediate the chromium (Cr) contaminated soil and water. In this study, Shewanella putrefaciens (MTTC8410) was used to investigate the influence of carbon concentration, pH, and temperature on reduction of hexavalent chromium [Cr(VI)] into trivalent chromium [Cr(III)]. The increased bacterial growth rate was significantly reduced the Cr(VI) concentration. In batch mode experiments, 1% starch recorded the highest reduction of Cr(VI) (90%) followed by 1% glucose (88% reduction) and a reduction of 77% was by 1% cellulose. By using various pH conditions the maximum Cr(VI) reduction was achieved at pH 7.0. In this experiment the maximum Cr(VI) reduction (75%) was observed at 35°C, followed by 30°C with 62% of Cr(VI) reduction. Bioreactor analysis revealed the highest reduction of Cr(VI) (88%) in unsterile tannery effluent. The significant levels of physico- chemical parameters were reduced in unsterile tannery effluent, as compared to the sterile tannery effluent. The experimental results revealed that the S. putrefaciens (MTTC8410) could be used as a potential bacterial strain for reduction of Cr(VI) from contaminated groundwater.

Highlights

Chromium (Cr) is the seventh most abundant element on earth, the twenty-first metal in the earth’s crust and is mined as chromites[1,2]
1% starch recorded the highest reduction of Cr(VI) (90%) followed by 1% glucose (88% reduction) and a reduction of 77% was by 1% cellulose
Cr(VI) at a concentration of 10 to 30 mg/L have negatively effect on the growth of the bacteria

Summary

Introduction

Chromium (Cr) is the seventh most abundant element on earth, the twenty-first metal in the earth’s crust and is mined as chromites[1,2]. The tannery industry is among the most contaminating industrial sectors and in the process of leather manufacture each tannery industry uses vast amounts of chemicals. The leather industries which widely use compounds containing Cr(III) in the tanning process generally release Cr(VI) effluents into natural water supplies, often without adequate effluent treatment, leading to anthropogenic contamination in water sources[3]. Chromium is one of the main contaminants in various engineering processes including tannery, electroplating, mining, fibre, metal processing, fertilizer, coloring and manufacturing of pigments[4]. Cr(VI) is one of the most toxic and causes various human health problems symptoms including nasal and skin irritation and lung carcinoma. Cr can be found in various oxidation forms; Cr (VI) is the most toxic and soluble and Cr (III) is the least toxic form to human beings

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Results

Conclusion