Thioleaching of Heavy Metal Contaminated Sediments Using Matin's Medium

Heavy metal contaminated spoils abound in the Niger Delta as a result of oil exploration dredging activities. This study involves the isolation and enrichment of indigenous mesophilic acidithiobacilli from abandoned spoils in Warri River and used for the controlled leaching of heavy metals from two different abandoned dredged spoils using Matin's medium under semi static conditions in laboratory shake flasks. After seven weeks of bioleaching, the heavy metal recoveries from spoil 1 are copper (81%), cadmium (86%), chromium (34%), nickel (61%), manganese (63%) and zinc (82%). Spoil 2 had a similar trend. Phyisco-chemical parameters monitored (acidity, sulphate, conductivity, turbidity and optical density) increased alongside the population of the actively growing acidithiobacilli. The pattern of heavy metal release from the spoils appears to involve the microbial oxidation of metal sulphides causing the formation of metal sulphates. We therefore conclude that microbial thioleaching processes can be used to recover heavy metals from contaminated dredged spoils prior to abandonment to prevent environmental pollution.