RESUMO
The oxidative systems including enzymatic systems have been widely studied as an alternative for textile effluents treatment. However, studies have shown that some oxidative processes can produce degradation products with higher toxicity than the untreated dye. In this work, enzymatic dye decolorization was evaluated by horseradish peroxidase enzyme (HRP) and the toxicity of discoloration products was evaluate against Daphnia magna, Euglena gracilis algae, and Vibrio fischeri. Dye decolorization kinetics data were evaluated and the pseudo-second-order model showed the best-fitting to the experimental data. In addition, it was observed an increased acute and chronic toxicity associated with the decolorization efficiency. The Reactive Blue 19 and Reactive Black dye showed the highest toxicity against D. Magna (16 toxicity factor) and V. Fischeri (32 toxicity factor) after enzymatic decolorization. For the chronic toxicity against D. Magna, Reactive Red was the only dye with no fertility inhibition. In relation to toxicity tests with E. gracilis algae, it was not observed photosynthetic inhibition for all dyes. This study verified the viability of the enzyme horseradish peroxidase in the textile dyes decolorization and the importance to evaluate the decolorization products.
Assuntos
Corantes/química , Peroxidase do Rábano Silvestre/química , Poluentes Químicos da Água/química , Aliivibrio fischeri/efeitos dos fármacos , Aliivibrio fischeri/metabolismo , Animais , Cor , Corantes/toxicidade , Daphnia/efeitos dos fármacos , Daphnia/fisiologia , Euglena gracilis/efeitos dos fármacos , Euglena gracilis/fisiologia , Feminino , Longevidade/efeitos dos fármacos , Luminescência , Masculino , Fotossíntese/efeitos dos fármacos , Reprodução/efeitos dos fármacos , Soluções , Têxteis , Poluentes Químicos da Água/toxicidadeRESUMO
Ionic liquids (ILs) are often claimed to be "environmentally friendly" compounds however, the knowledge of their potential toxicity towards different organisms and trophic levels is still limited, in particular when protic ionic liquids (PILs) are addressed. This study aims to evaluate the toxicity against various microorganisms and the biodegradability of four PILs namely, N-methyl-2-hydroxyethylammonium acetate, m-2-HEAA; N-methyl-2-hydroxyethylammonium propionate, m-2-HEAPr; N-methyl-2-hydroxyethylammonium butyrate, m-2-HEAB; and N-methyl-2-hydroxyethylammonium pentanoate, m-2-HEAP. The antimicrobial activity was determined against the two bacteria, Sthaplylococcus aureus ATCC-6533 and Escherichia coli CCT-0355; the yeast Candida albicans ATCC-76645; and the fungi Fusarium sp. LM03. The toxicity of all PILs was tested against the aquatic luminescent marine bacterium Vibrio fischeri using the Microtox(®) test. The impact of the PILs was also studied regarding their effect on lettuce seeds (Lactuta sativa). The biodegradability of these PILs was evaluated using the ratio between the biochemical oxygen demand (BOD) and the chemical oxygen demand (COD). The results show that, in general, the elongation of the alkyl chain tends to increase the negative impact of the PILs towards the organisms and biological systems under study. According to these results, m-2-HEAA and m-2-HEAP are the less and most toxic PILs studied in this work, respectively. Additionally, all the PILs have demonstrated low biodegradability.
Assuntos
Líquidos Iônicos/toxicidade , Compostos de Amônio Quaternário/toxicidade , Aliivibrio fischeri/efeitos dos fármacos , Aliivibrio fischeri/metabolismo , Antibacterianos/química , Antibacterianos/metabolismo , Antibacterianos/toxicidade , Antifúngicos/química , Antifúngicos/metabolismo , Antifúngicos/toxicidade , Biodegradação Ambiental , Análise da Demanda Biológica de Oxigênio , Candida albicans/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Fusarium/efeitos dos fármacos , Líquidos Iônicos/química , Líquidos Iônicos/metabolismo , Lactuca/efeitos dos fármacos , Lactuca/crescimento & desenvolvimento , Luminescência , Compostos de Amônio Quaternário/química , Compostos de Amônio Quaternário/metabolismo , Staphylococcus aureus/efeitos dos fármacosRESUMO
Nowadays, the classification of industrial solid wastes is not based on risk analysis, thus the aim of this study was to compare the toxicity classifications based on the chemical and ecotoxicological characterization of four industrial sludges submitted to a two-step stabilization/solidification (S/S) processes. To classify S/S products as hazardous or non-hazardous, values cited in Brazilian chemical waste regulations were adopted and compared to the results obtained with a battery of biotests (bacteria, alga and daphnids) which were carried out with soluble and leaching fractions. In some cases the hazardous potential of industrial sludge was underestimated, since the S/S products obtained from the metal-mechanics and automotive sludges were chemically classified as non-hazardous (but non-inert) when the ecotoxicity tests showed toxicity values for leaching and soluble fractions. In other cases, the environmental impact was overestimated, since the S/S products of the textile sludges were chemically classified as non-inert (but non-hazardous) while ecotoxicity tests did not reveal any effects on bacteria, daphnids and algae. From the results of the chemical and ecotoxicological analyses we concluded that: (i) current regulations related to solid waste classification based on leachability and solubility tests do not ensure reliable results with respect to environmental protection; (ii) the two-step process was very effective in terms of metal immobilization, even at higher metal-concentrations. Considering that S/S products will be subject to environmental conditions, it is of great interest to test the ecotoxicity potential of the contaminants release from these products with a view to avoiding environmental impact given the unreliability of ecotoxicological estimations originating from chemical analysis.