Bio-Degradation of Cyanide of Coke Coal Unit of Rourkela Steel Plant

Abstract

Cyanide is a toxic compound which is produced by some foods, certain microorganisms, plants as well as some animals. Though their production by the above sources is less, metal finishing as well as mining industries are the main cause of cyanide pollution. However cyanide is used for extraction of gold from ores, electroplating, coal gasification etc; their occurrence in large scale in the environment is highly hazardous for the living beings. To avoid these hazards Central Pollution Control Board (CPCB) has set minimal cyanide level in effluent as 0.2 mg/L. In order to achieve this, various physical, chemical as well as biological methods were adopted. Biological methods were found to be most useful and less expensive compared to others; which include use of algae, fungi and bacterial cultures. In the present study, bacterial colonies were isolated from the water sample of AT I and efficient cyanide degrading colony was isolated. Various process parameters such as pH, temperature, and inoculum size were studied and optimized for obtaining maximum cyanide degrading efficiency. A comparative study between Granular Activated Carbon (GAC) and clinker was carried out in order to identify their adsorption capacities. Optimum conditions for biodegradation were obtained and a simultaneous adsorption and biodegradation (SAB) study was carried out at neutral pH of 6.5-7.5, temperature 30°C, and inoculum size of 1 mL. Using SAB process, maximum cyanide degradation was found to be 99.16 %.