Biorremediação em derramamento de petróleo com ênfase na técnica de encapsulamento de micro-organismos consorciados

Abstract

Oil spills cause severe environmental and economic impacts, so the bioremediation technique has been widely studied in order to use microorganisms for the degradation of petroleum. Due to its complex composition, petroleum makes the action of the microorganisms difficult in relation to the metabolization of its components and, therefore, the use of the encapsulation with plant biomass insertion provides protection and initial metabolic input for the production of biosurfactants, which increase the surface area of contact between the metabolites and the microorganisms, resulting in increased degradation of the compounds and greater efficiency in the bioremediation process. Therefore, the objectives of the present work are to analyze the capsules produced with the use of sodium alginate, plant biomass and microorganisms through techniques such as: TGA, DSC, MEV-FEG and viable bacterium cell counting, set up a fractional factorial experimental design to analyze the importance of the variables: capsule concentration, oil dilution, agitation, temperature, process duration and substrate used (crude oil or pure aliphatic fraction), and then evaluate the degradation of the oil using encapsulated microbial cells through a factorial design. The results of TGA and DSC showed that the capsules have thermal stability up to 42 °C and that growth of the microorganisms increases stability and thermal resistance of bacterium consortium. MEV-FEG showed the presence of pores in the capsular membrane and number of viable bacterium cell counts was increases in capsules containing 1% (w / v) sodium alginate. The emulsification index showed a large increase (80%) from the fifth day, just as the surface tension had a great decrease (48%) in the same period, indicating a higher biosurfactant production. The degradation analysis showed that all variables have an impact on the biological process, however, the most important are: substrate concentration, time, agitation and temperature. Therefore, the full factorial design indicated that there was an increase in C12 concentration in most samples, showing that the higher chain hydrocarbons are being degraded in the first place. As for the capsular analyzes, they showed excellent thermal stability and porosity, increased microbiological growth at low sodium alginate concentrations, decreased surface tension and increased emulsification in the presence of petroleum.