Detoxification of Tunisian landfill leachates by selected fungi

Young landfill leachates (LFL) collected from Djebel Chekir (Tunisia) discharge area were found to be highly loaded with organic matter, ammonia, salts, heavy metals, phenols and hydrocarbons. Despite the possibility of their biodegradability, they represent a threat to the environment and show some resistance to conventional wastewater treatment processes. For these reasons, this study attempted to develop a biological process for the treatment of LFL using selected strains of Trametes trogii, Phanerochaete chrysosporium, Lentinus tigrinus and Aspergillus niger. Experiments were undertaken at different concentrations of the effluent up to 100%. COD removal efficiencies for P. chrysosporium, T. trogii and L. tigrinus were of 68, 79 and 90%, respectively, when LFL underwent a two-fold dilution. COD abatements were accompanied with an important enzyme secretion and a high reduction in the toxicity, expressed as percent bioluminescence inhibition (%BI < 20%). Above 50% of LFL, the effluent was toxic to these strains and caused growth inhibition indicating the sensitivity of these strains to concentrated LFL. Comparatively to the other tested strains, A. niger showed to tolerate raw LFL since it grew at 100% of LFL. However, this strain is inefficient in removing phenols and hydrocarbons. Consequently, toxicity abatement was very low (%BI > 70%).