Bioremediation of Cadmium Ions by Bacillus mucilaginosus and Its Removal Mechanism

The physical and chemical factors can affect the activities of microorganisms, urease activity, and the removal effect of heavy metal ions. The Bacillus mucilaginosus was cultured and mineralized to remove Cd 2+ ions from aqueous solution under different environmental conditions. The effects of time, temperature, pH, volume ratio, and Cd 2+ concentration on the mineralization of Cd 2+ ions were studied. The experimental results showed that the urease activity in the bacteria reached the highest value when the ambient temperature was 301 K, the shaking table was set at 180r/min, and the culture time was 48 h. In the process of mineralization removal, the optimal removal temperature is 318 K, the optimal pH is 8.5, and the removal efficiency is as high as 90.01% when the concentration of Cd 2+ is 500 mg/L. X-ray diffraction (XRD) patterns showed that Cd 2+ ions could be mineralized to form CdCO 3 . The microstructure of the precipitates was observed by a scanning electron microscope (SEM). Therefore, the application of microbial mineralization technology to the treatment of heavy metal pollution has a promising prospect.