Características físico-químicas, microbiológicas e ecotoxicológicas de efluentes têxteis e proposta de tratamento por coagulação/floculação
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2021-02-05
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Universidade Estadual Paulista (Unesp)
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Efluentes têxteis são túrbidos, alcalinos, geralmente constituídos por altas concentrações de corantes, sólidos suspensos e dissolvidos, compostos orgânicos e inorgânicos, além de apresentarem quantidades significativas de bactérias viáveis, coliformes totais, termotolerantes e elevados níveis de ecotoxicidade. Devido ao grande potencial que efluentes têxteis detêm em causarem danos à saúde de humanos e ao meio ambiente, seus tratamentos são considerados como fundamentais. Métodos de coagulação/floculação e adsorção têm sido vistos por serem uma alternativa atraente no tratamento de efluentes têxteis. Os métodos, ainda que tenham demonstrado grande eficácia em estudos laboratoriais, têm enfrentado limitações quanto às suas implementações em escalas reais de tratamento têxteis, relacionadas principalmente com os custos dos processos e com o potencial ecotoxicológico que alguns compostos sedimentadores podem apresentar. Nesta Tese, utilizando-se de planejamentos estatísticos fatoriais e testes ecotoxicológicos de germinação da L. sativa, foi avaliado a eficiência da descoloração e efeito ecotóxico que o sulfato ferroso, policloreto de alumínio, carvão ativado e poliacrilamida aniônica ocasionavam em uma solução que continha o corante Acid Red 114. Os planejamentos experimentais, que possuíam as características de rotatabilidade e ortogonalidade, permitiram analisar com robustez os efeitos individuais e combinados dos fatores, calcular a magnitude da variabilidade experimental e derivar funções que descreviam o comportamento dos resultados. Os modelos estatísticos, sobretudo, foram capazes de estimar as concentrações de coagulantes, floculante e adsorvente que ocasionavam as melhores eficiências de descolorização e os menores efeitos ecotoxicológicos, assim, favorecer a implementação dos métodos em escalas reais de tratamento de efluentes têxteis.
Textile effluents are turbid, alkaline, generally consisted by high concentrations of dyes, suspended and dissolved solids, organic and inorganic compounds, in addition to significant amounts of viable bacteria, total coliforms, thermotolerant coliforms and high ecotoxicological levels. Due to the great potential that textile effluents have in causing damage to the health of humans and the environment, their treatments are considered as fundamental. Coagulation/flocculation and adsorption methods were seen to be an attractive alternative in the treatment of textile effluents. The methods, although they have demonstrated great efficacy in laboratory studies, have faced limitations regarding their implementation in real scales of textile treatment, mainly related to the costs of the processes and the ecotoxicological potential that some sedimenting compounds may exhibit. In this Thesis, using factorial statistical plans and ecotoxicological tests of L. sativa germination, it was evaluated the decolorization efficiency and ecotoxic effect that ferrous sulfate, aluminum polychloride, activated carbon and anionic polyacrylamide caused in a solution that contained the Acid Red 114 dye. The experimental designs, which had the rotatability and orthogonality characteristics, enabled a robust analysis of the individual and combined effects of the factors, the calculation of the magnitude of the experimental variability and the derivation of functions that described the behavior of the results. The statistical models, above all, were able to estimate the concentrations of coagulants, flocculant and adsorbent that caused the highest decolorization efficiencies and the lowest ecotoxicological effects, thus, supporting the implementation of the methods in real scales of textile effluent treatments.
Textile effluents are turbid, alkaline, generally consisted by high concentrations of dyes, suspended and dissolved solids, organic and inorganic compounds, in addition to significant amounts of viable bacteria, total coliforms, thermotolerant coliforms and high ecotoxicological levels. Due to the great potential that textile effluents have in causing damage to the health of humans and the environment, their treatments are considered as fundamental. Coagulation/flocculation and adsorption methods were seen to be an attractive alternative in the treatment of textile effluents. The methods, although they have demonstrated great efficacy in laboratory studies, have faced limitations regarding their implementation in real scales of textile treatment, mainly related to the costs of the processes and the ecotoxicological potential that some sedimenting compounds may exhibit. In this Thesis, using factorial statistical plans and ecotoxicological tests of L. sativa germination, it was evaluated the decolorization efficiency and ecotoxic effect that ferrous sulfate, aluminum polychloride, activated carbon and anionic polyacrylamide caused in a solution that contained the Acid Red 114 dye. The experimental designs, which had the rotatability and orthogonality characteristics, enabled a robust analysis of the individual and combined effects of the factors, the calculation of the magnitude of the experimental variability and the derivation of functions that described the behavior of the results. The statistical models, above all, were able to estimate the concentrations of coagulants, flocculant and adsorbent that caused the highest decolorization efficiencies and the lowest ecotoxicological effects, thus, supporting the implementation of the methods in real scales of textile effluent treatments.
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Efluente têxtil, Ecotoxicologia, Toxicidade aguda, Decantação, Adsorção, Corantes azo, Acid Red 114, DCCR, Textile effluent, Ecotoxicology, Acute toxicity, Decantation, Adsorption, Azo dyes, CCRD