In situ treatment of groundwater at Burgas copper mines, Bulgaria, by enhancing microbial sulphate reduction In situ treatment of groundwater at Burgas copper mines, Bulgaria, by enhancing microbial sulphate reduction Πλήρης Δημοσίευση σε Συνέδριο Conference Full Paper 2015-11-141998enThe groundwater in the area near the tailings ponds at the Burgas Copper Mines, Bulgaria, is contaminated with radionuclides, sulphates and toxic heavy metals (mainly copper, lead, molybdenum and manganese) by drainage waters from the pond. The groundwater level and the quality of groundwater were monitored regularly by a system of piezometers. It was found that natural cleanup processes took place during groundwater flow. The main cleanup process is the microbial dissimilatory sulphate reduction carried out by the indigenous sulphate-reducing bacteria. The hydrogen sulphide, produced as a result of this process, reduced the hexavalent uranium to the insoluble tetravalent state and precipitated the heavy metal ions as the relevant insoluble sulphides. The in situ activity of the sulphatereducing bacteria was enhanced by adding nutrients (soluble organic matter, ammonium and phosphate ions) to the groundwater through injection boreholes. The concentration of pollutants decreased below the permissible levels after such treatment. http://creativecommons.org/licenses/by-nc-nd/4.0/ 249-255International Conference on Groundwaters Quality: Remediation and ProtectionProceedings of International Conference on Groundwaters Quality: Remediation and Protection GROUDEV STOYAN KONTOPOULOS ANTONY SPASOVA IRENA KOMNITSAS KOSTAS ANGELOV ANATOLI GEORGIE PLAMEN