EFFECT OF PH AND TEMPERATURE ON THE REMOVAL OF HEAVY METALS BY AUTOCHTHONOUS BACTERIA FROM SOIL IN A GAS FLARING ENVIRONMENT

Abstract

The concentration of heavy-metals in soil is constantly being altered by activities of gas flaring in the environment. This study was carried out to assess the effect of pH and temperature on the removal of heavy-metals: Lead, Chromium, and Cadmium present in soils of gas-flaring communities using autochthonous heavymetal resistant bacteria. Thirty soil samples were each collected from three communities and a total of 120 bacteria strains isolated amongst which two were found to withstand mixtures of lead, Chromium and Cadmium contamination up to 500ppm. The isolates were subjected to 16S rRNA gene sequencing for identification which ares Salmonella enterica and Alcaligenes faecalis. The Effect of pH and temperature was studied at pH 5, 7, and 9 at 37℃ and temperatures of 35, 55, and 65℃ at pH 7 for 48hours to determine the rate of metal removal. At the end of 48hours, Salmonella enterica recorded the highest lead removal (74%) at pH 5 with a concentration of 300ppm, Chromium(85%) and Cadmium(86%) removal at pH 7 with a concentration of 400ppm. At a temperature of 55℃ with a concentration of 400ppm, the highest lead removal (82%) was recorded with Alcaligenes faecalis, while Chromium (85%) and Cadmium (86%) removal
with Salmonella enterica. Statistical analysis showed a significant difference in the concentration of heavy-metals before and after bioremediation. This study reveals that pH 5 and 7 and temperature of 55℃ at concentrations of 400ppm can thus be used for the removal of lead, Chromium and Cadmium in polluted soil in gasflaring environment