Applicazione dei funghi autoctoni e alloctoni nel biorisanamento dei reflui conciari e di percolato di discarica: aspetti fisico-chimici, enzimatici ed ecotossicologici

Industrial wastewaters have a wide variety of recalcitrant compounds that make difficult their degradation, remaining in the environment as toxic agents. The current wastewater treatments are often ineffective or unsustainable. Bioremediation seems to be promising from environmental and economic points of view. Fungi are the new frontiers of biodegradation mechanisms to treat wastewaters. This is supported by the fact that they are fundamental to degrade natural recalcitrant polymers. Besides, their role in xenobiotics bioremediation is of basilar importance, since they have complementary capability with respect to bacteria; thanks to the fungal treatment, activated sludge could work better. The study carried out as part of this thesis is a component of the FIRB project (code: RBFR13V3CH) developed by University of Turin, University of Florence and 3 Tuscan consortia of wastewater treatment. This project has as main objective to develop new to enable the application of fungi in the biological treatment of wastewater, in synergy with conventional treatment. The objective of this thesis was the evaluation of the performance of autochthonous and allocthonous fungi in the bioremediation of leather tannery wastewaters and landfill leachates. The parameter considered were: decolourisation, the ability to maintain the pH at acidic value as an index of active metabolism, enzymatic activity (laccases, peroxidases and tannases), ecotoxicity and chemical variation of TOC, COD, total N, phenols. Despite the autochthonous fungi are often pointed out as potential bioremediation agent, because of their pre-adaptation to the contaminated environment, all fungi selected at the end of this thesis were allochthonous ones, coming from the collection of the Mycotheca Universitatis Taurinensis (MUT). This underlines the importance of the Microbial Resources Centres as a source of well-characterised organisms potentially useful in biotechnological application. Bjerkandera adusta MUT 2295 and Lopharia spadicea MUT 1585 (for landfill leachate) and Aspergillus tubingensis MUT 2295 and Paecylomyces variotii MUT 1125 (for tannery effluent) highlighted great potentials, for their decolourisation yields and time fashion (24 h), high enzyme activity and production of phenols. The ecotoxicity and chemical parameters increased, however a combination of fungi with activated sludge could improve these aspects, leading to an extensive bioremediation of wastewaters. The study of these fungi at pilot plan is a work in progress at the Cuoiodepur wastewater treatment plant. In conclusion, fungi and their enzymes are effective biocatalysts whose versatility and stability make them good candidates for the application in bioremediation biotechnology. They cannot be considered in substitution of the current technologies, but represent a valid tool for the implementation of wastewater treatment, in order to improve of the quality of the treated water.