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Abstract(s)
O presente trabalho centra-se no desempenho dos reactores termófilos no tratamento
de efluente têxtil simulado. Foi avaliada a influência de um bioadsorvente (dreche) na
descoloração anaeróbia de corantes azo. Dois reactores UASB operaram a uma
temperatura de 55 ± 2ºC, com um tempo de retenção hidráulico de 7 horas, alimentados
com glucose, o substrato. O reactor termófilo, RT, foi inoculado com biomassa
anaeróbia mista e no outro foi incorporada dreche, RT-DC, na razão de 1:4
bioadsorvente / biomassa anaeróbia mista (v/v). Os resultados indicam, no global, uma
melhor performance para o RT-DC relativamente ao RT. Em média a taxa de remoção
de CQO foi de 3,8 ± 1,6 e de 4,3 ± 1,7 g CQO removido/L.d, para uma concentração de
corante de 60 mg/L, no RT e RT-DC respectivamente. A percentagem de remoção de
cor foi, para o corante Reactive Orange 16, de 76 ± 1% no RT e para o corante Acid
Orange 7 foi de 81 ± 1% no RT-DC.
Embora se tenham obtido bons resultados foi registada alguma instabilidade no
sistema, causada sobretudo por variações no caudal e no pH de alimentação, conduzindo
a um decréscimo na taxa de remoção de CQO. Ambos os corantes foram removidos,
contudo algumas aminas aromáticas geradas como metabolitos anaeróbios continuam
presentes na descarga dos reactores. Estes resultados foram confirmados através de
espectros de UV-visível. A presença da dreche no RT-DC parece também contribuir
para a eliminação de, pelo menos, um dos metabolitos do AO7, o 1-amino-naftol, pois
não foi detectada a sua presença nos cromatogramas de HPLC. Sob condições
termófilas o agente liposomal (fosfolípidos) foi testado como alternativa de co-substrato
à glucose. Em ambos os reactores registaram-se aumentos das taxas de remoção de
CQO e de remoção de cor. A integração do adsorvente anaeróbio no reactor (RT-DC)
parece contribuir para um aumento dos parâmetros de eficiência, tais como CQO, COT
e remoção da cor. Assim, a dreche (um resíduo da indústria cervejeira) pode ser
aplicada na condição de agente modificador e adsorvente em reactores anaeróbios,
representando um papel importante na performance do sistema. Seria importante a
realização de estudos complementares neste tipo de degradação, para se compreender
melhor a descoloração anaeróbia nestas circunstâncias
The present work is focused on the performance of thermophilic anaerobic reactors treating a simulated textile effluent. The influence of a biosorbent (spent brewery grains) on anaerobic decolourization of azo dyes was evaluated. Two upflow anaerobic sludge blanket reactors operating at 55 ± 2ºC, with a hydraulic retention time of 7h and fed with glucose as co-substrate were followed. The thermophilic reactor, TR, was inoculated with mixed anaerobic biomass and the integrated biosorption-anaerobic thermophilic reactor, TR-B, was inoculated with a 1:4 biosorbent /mixed anaerobic biomass ratio (v/v). Results indicate an overall better performance for the TR-B system relatively to TR. In average a COD removal rate of 3.8 ± 1.6 and 4.3 ± 1.7 g COD removed/L.d for a dye concentration of 60 mg/L could achieved for TR and TR-B respectively. The percentage of colour removal was in average, for dye Reactive Orange 16, of 76 ± 1 % in TR and for the dye Acid Orange 7 of 81 ± 1 % in the TR-B system. Although these good results have been obtained, some instability of both systems were registered, caused mainly by flowrate and pH feed variations, leading to a decrease of the COD removal rates. Both dyes were removed, however some aromatic amines generated as anaerobic metabolites still remained in the out of the reactors. These results were checked by UV-visible spectra. The presence of spent brewery grains in the reactor TR-B seems also to contribute for the elimination of, at least, one of the AO7 metabolites, the 1-amino-naphtol, since its presence was not detected in the HPLC chromatograms. Under thermophilic regime a liposome agent (phospholipids) tested as an alternative co-substrate to glucose in both reactors for decolourization tests depicted an increase of both COD and colour removal rates. The integrated anaerobic-biosorption reactor (TR-B) seems to display an improvement of the efficiency parameters, such as COD, TOC and colour removal. This shows that spent brewery grains (a by-product of brewery industry) could be applied as a conditioning along with as an adsorvent agent in anaerobic reactors, playing an important role in the performance of the system. Some complementary studies on its degradation are also necessary in order to have a better understanding of the anaerobic decolourization under these circumstances.
The present work is focused on the performance of thermophilic anaerobic reactors treating a simulated textile effluent. The influence of a biosorbent (spent brewery grains) on anaerobic decolourization of azo dyes was evaluated. Two upflow anaerobic sludge blanket reactors operating at 55 ± 2ºC, with a hydraulic retention time of 7h and fed with glucose as co-substrate were followed. The thermophilic reactor, TR, was inoculated with mixed anaerobic biomass and the integrated biosorption-anaerobic thermophilic reactor, TR-B, was inoculated with a 1:4 biosorbent /mixed anaerobic biomass ratio (v/v). Results indicate an overall better performance for the TR-B system relatively to TR. In average a COD removal rate of 3.8 ± 1.6 and 4.3 ± 1.7 g COD removed/L.d for a dye concentration of 60 mg/L could achieved for TR and TR-B respectively. The percentage of colour removal was in average, for dye Reactive Orange 16, of 76 ± 1 % in TR and for the dye Acid Orange 7 of 81 ± 1 % in the TR-B system. Although these good results have been obtained, some instability of both systems were registered, caused mainly by flowrate and pH feed variations, leading to a decrease of the COD removal rates. Both dyes were removed, however some aromatic amines generated as anaerobic metabolites still remained in the out of the reactors. These results were checked by UV-visible spectra. The presence of spent brewery grains in the reactor TR-B seems also to contribute for the elimination of, at least, one of the AO7 metabolites, the 1-amino-naphtol, since its presence was not detected in the HPLC chromatograms. Under thermophilic regime a liposome agent (phospholipids) tested as an alternative co-substrate to glucose in both reactors for decolourization tests depicted an increase of both COD and colour removal rates. The integrated anaerobic-biosorption reactor (TR-B) seems to display an improvement of the efficiency parameters, such as COD, TOC and colour removal. This shows that spent brewery grains (a by-product of brewery industry) could be applied as a conditioning along with as an adsorvent agent in anaerobic reactors, playing an important role in the performance of the system. Some complementary studies on its degradation are also necessary in order to have a better understanding of the anaerobic decolourization under these circumstances.
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Keywords
Industria têxtil - Efluentes Corantes azo