Biosorption of lead, chromium and cadmium in tannery effluent using indigenous microorganisms

This study investigated the biosorption of lead, chromium and cadmium in tannery effluent using indigenous microorganisms. Bacteria isolated from the tannery effluent were Bacillus subtilis and B. megaterium while fungi isolated were Aspergillus niger and Penicillium sp. The microorganisms were tested for their ability to reduce the concentration of the heavy metals in the tannery effluent using conventional methods. B. megaterium recorded the highest lead reduction (2.13 to 0.03 mg/L), followed by B. subtilis (2.13-0.04 mg/L). A. niger recorded the highest ability to reduce the concentration of chromium (1.38-0.08 mg/L) followed by Penicillium sp. (1.38 0.13 mg/L) while B. subtilis exhibited the highest ability to reduce the concentration of cadmium (0.4-0.03 mg/L) followed by B. megaterium (0.04-0.06 mg/L) after 20 days. When these values were compared to standard limits of Federal Environmental Protection Agency (FEPA), World Health Organization (WHO), National Environmental Standard and Regulations Enforcement Agency (NESREA) and Central Pollution Control Board (CPCB), the isolates recorded an acceptable reduction in the concentration of lead, chromium and cadmium in sterile and unsterile tannery effluent. The results of this showed that the isolates reduced the concentration of lead, chromium and cadmium present in the sterile and raw tannery effluent and suggest that the organisms can be used as a possible treatment of tannery effluents.