BIOREMEDIATION OF CYANIDE FROM GOLD EXTRACTION TAILINGS RUNOFF USING THE BACTERIUM CITROBACTER FREUNDII STRAIN SKC-4

• Main Author: Arfani Rahman, Hanif
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/56981
• Institution: Institut Teknologi Bandung

Cyanidation is one of many techniques used in the gold extraction process. Cyanidation uses cyanide in the form of NaCN or KCN, which concentration is adjusted to get the optimal gold extraction percentage. After the gold ores are unable to be extracted its valuable metal anymore, they will be collected into tailing storage facilities for further treatments. Several problems will occur when the tailing storage facilities are full and overflow caused by rainfall, whereas in that ponds still contain cyanide that is hazardous for the environment. Therefore, tailings runoff should be done several treatments to reduce its cyanide concentration. This research aims to degrade cyanide concentration from PT X tailings runoff using Citrobacter freundii strain SKC-4 that cultured in SKC-1 media. The experiments were started with the study of literatures to find out the many types of bacteria and their mechanisms in cyanide degradation. After that, experiments were constructed to select some bacterias that able to survive in a cyanide environment and its optimal media, until five strains of bacteria were chosen and its optimal media is SKC-1. That five bacterias were cultured in SKC-1 media, later centrifugated and inoculated to PT X tailings runoff sample to be tested for cyanide degradation experiment. Cyanide concentrations were determined using the spectrophotometry method which read absorbance of the sample that already added ninhydrin indicator. The most optimal bacteria would be chosen in this experiment, then would be tested again using varied inoculum sizes until the most optimal value was obtained. The next experiment was the measurement of bacterial growth from several initial concentrations of cyanide to determine the kinetics of cyanide bioremediation using that bacteria. The results of the experiments, the most optimal bacteria in cyanide degradation is Citrobacter freundii strain SKC-4 with inoculum size 20%. The initial concentration of cyanide in PT X tailings runoff sample is 0.064 ppm, and under that condition the bacteria is able to degrade cyanide concentration up to 0 ppm in 48 hours. The cyanide degradation rate is 0.143 X ppm/hour and the degradation percentage is 100%. The bacterial growth rate of Citrobacter freundii strain SKC-4 is determined using Monod Equations, and the result is dX/dt = 3,101 × 10-4 ppm/hour which X represents the concentration of bacteria at that time.