Preferential removal of lead, cadmium and zinc from contaminated agricultural soil by Bacillus Subtilis

Abstract

This work examined the preferential removal of lead, cadmium and zinc by Bacillus stubtilis from Amaonye Ishiagu contaminated forest soils. It focused also on the evaluation of optimum values of the factors required for the bioremediation analysis. Soil sample collected from the contaminated forest soil was aseptically transported to the laboratory where Bacillus substilis was isolated from the soil and cultured through microbiological analysis. 24 hours old organism was harvested from nutrient agar and inoculated into 3 grams each of the soil samples prepared for experiments. Optimum values of factors were determined on the 7^th day to be 8ml of nutrient, 5g of the organism, 30oC of temperature, pH of 8 and stirring frequency of 4pw. The bioremediation ability of the organism was experimented and evaluated at time 7, 14, 21, 28 and 35 days with the experimental condition set with the selected optimum factors’ values. The study discovered that Bacillus subtilis has more ability to remove lead before cadmium and then zinc from this soil with a removal efficiency of 75.7% to78.25 % for Lead at 14 days to 35 days; 59.64 % for cadmium at 35 days; and 4.71% for zinc at 35 days. At this 35 days duration, the organism was found fit for remediating lead polluted soil, fit for abating cadmium pollution at low concentration, but not fit for zinc pollution remediation and abatement.