Study on Ochrobactrum pseudintermedium ADV31 for the removal of hexavalent chromium through different immobilization techniques

Abstract

Chromium (VI) is one of the toxic heavy metals causing various human ailments like asthma to severe forms of cancer; hence, its removal from industrial effluents is essential. The present study demonstrates ameliorating techniques for the removal of Cr(VI). A chromium-reducing bacterium (CRB) identified as Ochrobactrum pseudintermedium ADV31 through 16S rRNA gene sequencing, was found to remove concentrations of Cr(VI) up to 600 mg/L in nutrient medium. Calcium alginate (CA) and polyurethane foam (PUF) were the two different materials used for the immobilization of Ochrobactrum pseudintermedium ADV31. The efficiency of the immobilized cells and free form of bacterial cells with inoculum concentrations of 1% and 5% were compared for the removal of Cr(VI). Calcium alginate with 5% inoculum concentrations showed removal of 82% of 600 mg/L in 5 days, while PUF with 5% inoculum size showed removal up to 86% of 600 mg/L in 5 days. Free form of bacterial cell was able to remove 36.7%. The bacterium was able to tolerate a wide range of pH ranging from 6 to 9 and had an optimum temperature of 45 °C. The results confirmed that both forms of immobilization methods are equally effective for the removal of hexavalent chromium and can be used for various biotechnological processes for the metal bioremediation.