An efficient lab-scale soil bioreactor for the removal of chromium (Cr) and arsenic (As) contaminated soil using co-culture

ABSTRACT

Heavy metal pollution has become a serious global threat in recent times which are mostly caused by anthropogenic activities. Bioremediation is cost-effective and eco-friendly technique. In the present study, bioremediation of the co-metal was performed by isolating chromium (Cr) and arsenic (As) resistant bacterial strains and its optimisation of different environmental parameters such as pH, temperature, carbon sources, nitrogen sources and vari+ous concentrations of chromium and arsenic were studied. The isolated co-culture bacterial strains were identified with biochemical and molecular identification using 16s RNA sequencing. Further, a lab-scale soil bioreactor was set up and mineralisation of chromium and arsenic was observed using different heavy metal contaminated soil samples. About 51.1% Chromium was mineralised by the co-culture, 26.7% in cycle 2, 22% in cycle 3 and 34.2% in cycle 4 respectively. The Arsenic mineralisation was 16.7%,23.7%,35.4% and 35.8% at the end of 4 cycles. The final mineralised concentration was analysed by Inductively coupled plasma optical emission Mass spectrometry (ICP-MS) resulting in 29.9 of Chromium and Arsenic 0.083 mg/L respectively. The physico-chemical parameters, such as pH, temperature, TS, TDS, BOD and COD were monitored for the mineralisation study in the soil slurry bioreactor. The study proved that there was effective mineralisation of the co-metals with the cocultures of the isolated bacterial strains from the metal contaminated site.

KEYWORDS:

• Chromium
• arsenic
• toxic pollutants
• mineralisation
• soil-bioreactor

Acknowledgments

We want to thank the Principal and Management of Stella Maris College (Autonomous) for their constant support. We would like to thank the DST-FIST and CRIST Laboratory of Stella Maris College (Autonomous) for the Instrumental Facility.

Disclosure statement

No potential conflict of interest was reported by the authors.