Removal of Toxic Metals in Wastewater through Biomineralization

Abstract

Due to anthropogenic activities, heavy metals are one of the most toxic xenobiotics contaminating our soil today. The excessive release of untreated wastewater leads to an increase in salinity in water and soil. Conventional methods are not eco-friendly and more expensive for application on a larger scale. Biomineralization is a natural phenomenon occurring in a wide variety of living organisms which leads to production of minerals. Heavy metals are much more toxic in ionic form and the toxicity is significantly reduced when immobilized by reacting with carbonates, sulphides, silicates etc. due to a considerable decrease in solubility because of precipitation. The present study investigates the role of biomineralization by ureolytic halophilic bacteria to remove heavy metals- cadmium and arsenic through microbially induced calcium carbonate precipitation. Calcium carbonate precipitation by bacteria resulted in a significant decrease in the initial heavy metal concentration and removal through precipitation within 7 days of inoculation. The microstructural analysis of the bio-precipitates using FESEM and EDX revealed immobilization of heavy metal by calcium carbonate.