Avaliação do pré-tratamento do efluente de indústria química com adição de linhagens microbianas especializadas na degradação de compostos tóxicos

Abstract

MACHADO, F. S. Evaluation of the industrial wastewater pretreatment adding microbial strains specialized in toxic compounds degradation. 98 f. Master thesis (Biotechnology) – Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, 2009. Chemical industries are considered the industrial sector that generates the most dangerous effluents to the environment. The disposal of these effluents in receptor bodies is regulated by federal and state laws. Due to the high pollutant concentration, either organics or inorganics, the chemical industries effluents may interferer in the biomass activity in wastewater treatment plants (WWTP), what may reduce its efficiency and generate effluents in disagreement to the concerned law. Such effluents, even treated, may cause toxicity to the aquatic ecosystem. In order to prevent such effects, the industrial effluents disposal in WWTPs can be preceded by biological pretreatment, which can be optimized by adding microorganisms capable of pollutants degradation. Microorganism strains with the degrading capacity over organic compounds were isolated from the wastewater treatment plant. These strains are able to degrade the compounds identified as the responsible for toxicity levels in the WWTP final effluent: benzene, chloroform, 1,2-dichloroethane, pentachlorophenol, trichloroethene, tolune and p-xylene. Acute ecotoxicity tests have confirmed the relationship between such compounds and the inhibition events over the WWTP biological process. Bioaugmentation tests aiming the chemical effluent pretreatment were performed before it has been disposed in the WWTP, by using the isolated strains. The tests were evaluated through physical-chemical analysis and acute toxicity tests for Vibrio fischeri and Daphnia similis. The results showed that the WWTP contain microorganisms that are capable of degrading the toxic compounds responsible for toxicity, and the bioaugmentation tests performed with microbial consortia were more efficient than the ones performed with pure strains. Moreover, the industrial pretreatment was a better option for toxicity reduction than the microbial or consortia addiction directly in the WWTP biologic reactor. The toxicity tests were useful tools to demonstrate that the industrial effluent pretreatment reduced intensely the toxicity levels in the WWTP final effluent. Amplified rDNA restriction analysis showed the diversity of the organic pollutants degraders.