Aplicação da Eichhornia Crassipes no tratamento de ambientes contaminados por petroderivados.

Abstract

Spills of petroleum products and heavy metals are considered toxic to ecosystems by they contain large amounts of xenobiotics. Among the possible solutions, for the treatment of these pollutants, are the use of constructed wetlands, where it is possible to carry out phytoremediation processes, and the use of biosurfactants, which are biodegradable tensoactive agents. In this context, macrophytes of the species Eichhornia crassipes, plants that impact the environment by proliferating rapidly, were investigated in the treatment of these pollutants in the formation of wetlands and as a source of surfactants. Initially, the efficiency of a hybrid system by dissolved air flotation and wetlands was evaluated in the treatment of industrial oily water. Then, root residues from wetlands were reused in the extraction of surfactants. The presence of surfactant in the concentrated plant extract was studied, as well as toxicity tests using as bioindicators the microcrustacean Artemia salina and the seeds of Brassica oleracea, emulsification activity (motor oil, diesel, n-hexadecane, kerosene, corn oil and soybean oil), stability against pH, temperature and salinity and the chemical composition of the plant extract were carried out. In addition, the vegetal extract was applied to remove petroleum derivative (motor oil) in sand through kinetic and static tests, in the dispersion of the motor oil in sea water and in the removal of heavy metals in synthetic effluent (Pb, Cu and Zn). The efficiency obtained in the prototypes was 97% of oil removal. The obtained surface tension was 27.57 mN/m and the motor oil’s emulsification indexes reached 65%, indicating a great affinity of the plant surfactant to the oil. The stability tests of the vegetal extract showed little variation in its surface tension for all conditions tested. The plant Critical Micellar Concentration was 1.4 g/L with a surface tension at that point of 25.84 mN/m. E. crassipes extract proved to be practically non-toxic to the tested bioindicators. The concentration of the plant surfarfactant (saponin) obtained was 1.29 g/L in the plant extract and the chemical characterization of this purified extract indicated that it falls into the category of unsaturated fatty acid. The plant extract was able to disperse 100% of the motor oil in sea water. The percentage of motor oil removed in sand reached around 67% and the percentage of heavy metals removed approached 55%. The results obtained in this research clearly demonstrate the feasibility of applying E. crassipes as a biotechnological agent for environmental remediation processes.