Potential, isolation, and characterization of bacteria isolates from a coal ash dumpsite for recovery of nickel from coal fly ash

Abstract

Nickel is one of the heavy metals that has potential uses in industrial factories. The high demand for nickel causes various efforts to be made to recover nickel from waste. In general, metal recovery is carried out using chemicals in large quantities, so the cost is quite high, and it is harmful to the environment. The recovery of metals using microorganisms, such as bacteria, is quite promising. Therefore, this research will isolate and characterize bacteria from coal ash stockpiles and analyze the potential of these bacteria in nickel recovery through the bioleaching process. Bacterial isolation was carried out by taking a composite sample using the purposive sampling method, and the sample was inoculated into a selective medium for bacteria that play a role in bioleaching. Bacteria that have been isolated will be selected and characterized. Furthermore, these bacteria were tested for their potential in nickel recovery from coal fly ash through the bioleaching process. Bioleaching efficiency is measured to determine the potency of bacteria for nickel recovery. The results of this study showed that eight bacteria were successfully isolated. Characterization results show two gram-negative bacteria and two gram-positive bacteria. Of the eight bacteria, four showed potential for nickel recovery through good growth and higher nickel recovery than the other bacteria. These bacteria are also possibly used for other metal bioleaching processes.