Capacidade biodegradadora de fungos basidiomicetos Pleurotus ostreatus e Ganoderma sp. em efluentes da indústria do couro

Abstract

During the leather manufacturing process, there are stages where various chemical products are added, resulting in effluents with high toxicity and a significant organic load. These effluents are subjected to physical, chemical and biological treatments, essential to minimize the environmental impact. In the biological stage, microorganisms are used, such as bacteria, which present a good degradation of the organic material. Additionally, the use of fungi in the biotechnological sector is very attractive due to the characteristics that these microorganisms have, for example, a very dynamic and fast metabolism. Considering these specificities, in this study the biodegradation capacity was analyzed of the species Pleurotus ostreatus and Ganoderma sp. in samples of tannery effluents, including the possibility of reducing the amount of chromium (III) and (VI). To verify the resistance of the microorganisms to the effluent toxicity, the radial growth rate with and without the addition of effluents and the final mycelial biomass were analyzed. It was observed that both microorganisms were efficient in the treatments and that the shorter incubation time of fungi in the effluent results in better results, with a reduction above 90% for biodegradable material (BOD and COD) and above 70% for chromium (III) and (VI) species. The fungus taking in consideration that the Pleurotus ostreatus showed a greater growth demonstrating a lower sensitivity to the toxicity of the environment. In order to simultaneously verify the effect of a large number of variables from a reduced number of experiments, experiments for the treatment of the effluent were carried out through factorial planning with a central point, using as variables: i) the type of fungus; ii) the pH of the environment; iii) the exposure time. As answers, some demands as chemical oxygen demand (COD), biochemical oxygen demand (BOD), the amount of chromium (III) and chromium (VI) were used. The pH was the variable that proved to be the most significant for the removal of chromium (III) from the studied effluent therefore, it must be monitored within the stipulated ranges