Immobilization of Heavy Metals in Contaminated Soil using Calcium Phosphate Amendment and Phosphate-solubilizing Fungi (Penicillium sp) in Benin City, Edo state, Nigeria

Abstract

Soil is a limited resource that is continually contaminated by the presence of heavy metals as a result of human activities. This study used a combination of calcium phosphate amendment and phosphate-solubilizing fungi to immobilize heavy metals in polluted soil. Bovine bones were collected at an Abattoir Market in Aduwawa, Benin City, Nigeria with coordinates 6°22’6.24” N and 5°41’0.24” E and calcined to extract calcium-phosphate (hydroxyapatite), serial dilution and plating on Pikovskaya medium were utilized to obtain fungi extract from fertile soil. Prior to remediation, heavy metal analysis of polluted soil indicated high value of metal concentrations zinc 120.60mg/kg, chromium 22.67 mg/kg, cadmium 11.23 mg/kg, lead 18.43 mg/kg, iron 187.27 mg/kg and nickel 10.62 mg/kg above the World Health Organization permissible limit. There was a decrease in zinc and iron contents after the first week of treatment. The second week demonstrated a significant decrease in all metal concentrations; 27.53% for Zn, Cr 39.83%, Cd 46.13%, Pb 7.60%, Fe 46.26% and Ni 15.07% – indicating the treatment’s effectiveness.