Treatment of waters polluted with radioactive elements and heavy metals bymeans of a laboratory passive system

Waters polluted with toxic heavy metals, radioactive elements, arsenic and sulphates were efficiently treated by means of a laboratory-scale passive s ystem consisting of an anaerobic cell and a constructed wetland. These wate rs were polluted in a stream receiving leachates from an operating copper t ailings dam and other effluents from man-induced activities at the area of Vromos Bay in Bulgaria. The anaerobic cell contained a mixture of horse, co w and sheep manure, spent mushroom compost, wheat straw and sawdust which w ere used as sources of carbon and energy by different metabolically interde pendent microorganisms inhabiting the cell. The microbial dissimilatory sul phate reduction and the sorption on the organic matter were the main proces ses connected with the removal of pollutants. The effluents from the anaero bic cell were enriched in soluble organic compounds which were degraded in the constructed wetland containing rich microbial and plant cenoses. The ef fluents from the constructed wetland were suitable for use in the agricultu re and industry. (C) 1999 Published by Elsevier Science Ltd. All rights res erved.