Bioremediation of Cadmium, Lead, Zinc and Copper Contaminated Soils obtained from Dutse and Hadejia Regions by Lysinibacillus sphaericus Strain FUD-001 and Stenotrophomonas maltophilia Strain FUD-002 Immobilized on a Biochar

Toxic heavy metals have a detrimental impact on the human body and trigger acute or chronic effects or lead to cancer and death, gastrointestinal tract disorder, and nervous system breakdown. An efficient approach for the amelioration and restoration of soil heavy metal contamination is through bioremediation using biochar-immobilized bacteria. Soil samples were analyzed for Cadmium, Lead, Zinc, and Copper using Atomic Absorption Spectroscopy (AAS), and the isolates were subjected to heavy metal tolerant tests for Cd, Pb, Zn, and Cu at 50mg/L, 80mg/L, 100mg/L, and 150mg/L. The isolates were immobilized on a biochar produced from orange peels (Citrus sinensis) after morphological, microscopic, biochemical, and molecular identification, then subjected to a test for bioremediation potential for Cd, Pb, Zn, and Cu at concentrations of 10mg/L, 25mg/L, and 50mg/L. Biochar-immobilized Lysinibacillus sphaericus Cd percentage removal at 10mg/L, 25mg/L, and 50mg/L was 99.3, 99.7, and 99.8, respectively. Pb percentage removal was 100 for all three concentrations. Cd percentage removal for biochar-immobilized Stenotrophomonas maltophilia at 10mg/L, 25mg/L, and 50mg/L was 99.3, 99.7, and 99.8, respectively. Pb percentage removal at the same concentrations was 100. Orange peel was found to be a suitable substrate for biochar production and immobilization of bacteria. Chemical activation of the biochar using HNO3 improved its sorption capacity. Based on the result obtained, the biochar-bacteria complex is a highly remarkable strategy and can be employed in the bioremediation of heavy metal-contaminated soils.