Charges en metaux lourds, bacteries et virus, presentes dans les boues d'une station d'epuration par lagunage naturel heavy metal, bacterial and viral contamination of sewage sludges in oxidation ponds

Abstract

Abstract After nine years of operation, the sludge accumulation in a sewage treatment plant consisting of four ponds, equiped with a primary settling tank, is substantial. The agricultural value of the sludge is greatly reduced by the high level of mineralization. Most of the heavy metal and viral contamination is found in the first pond. Notwithstanding prolonged storage time, the load of fecal bacteries remains high. The degree of contamination with salmonella is low and limited to the first pond. The agricultural value of these sludges is poor and their land application will bring minimum benefit but will do little harm to the natural environment.