PRODUÇÃO DE BIOGÁS A PARTIR DA FERMENTAÇÃO ANAERÓBICA DE RESÍDUOS DA INDÚSTRIA MADEIREIRA E DO BIODIESEL

Abstract

The main byproduct from biodiesel generation is crude glycerin, which contains impurities that preclude the direct commercial use, bringing economic and environmental problems. This glycerin can be biologically transformed by microorganisms through anaerobic fermentation, wherein they release as a result of their metabolism gases such as hydrogen H2(g) and methane CH4(g), the principal biogas component. The paper and pulp industries (PPI) produce a large number of waste after the chemical, physical or mechanical wood processing, which present a several kind of sugars, and, as well as the crude glycerin, it can be assimilated by microorganisms during the fermentation, generating similar products with a high value added. The objective of this research is the production of biogas from crude glycerin and waste of PPI biomass anaerobic fermentation by Escherichia coli for energetical use. The microorganism viability was verified by plating and serial dilution technique and the total number of cells per ml was estimated by counting in a Neubauer chamber. Physical and chemical analysis were made for the glycerol characterization, such as pH, conductivity and density. The PPI residue was characterized by elemental composition, Spectroscopy in Infrared Region (IR), Scanning Electron Microscopy (SEM), moisture content, instant analysis and calorific value. Statistical analyses of the results were performed also as the analysis of kinetic aspects of the fermentation process. For the anaerobic fermentation samples were prepared from a multivariate 22 experimental design with a central point for each studied medium. After 72 h of fermentation, the CH4(g) and H2(g) production was registered by a gases detector. The best conditions for CH4(g) production were in samples with 5 mL of E. coli and 30% of PPI waste, and for H2(g) they were 10 mL of bacteria e 100% of cellulosic waste. It was possible to produce biogas from crude glycerin and PPI waste anaerobic fermentation by E. coli, characterizing it as an energetical way to utilize these byproducts.