Influence of Redox Mediators and Electron Donors on the Anaerobic Removal of Color and Chemical Oxygen Demand from Textile Effluent

Abstract

Color removal was evaluated in anaerobic assays using synthetic (SE) and real (RE) effluents containing the dye Direct Black 22 (DB22). The focus was on the individual influence of two electron donors (EDs), sucrose and ethanol; and their combination with two redox mediators (RMs), lawsone and riboflavin. In addition to SE assays, the EDs were combined with sulfate which was present in the RE. Distinct behavior was observed with both assays. In the case of SE, using the EDs sucrose and ethanol resulted in DB22 removal efficiency of 93 and 83%, respectively; but only 27% in the control. The respective removal rates were 27.8‐ and 4.4‐fold higher than that of the control. Using the EDs with the RM lawsone resulted in color removal higher than that with riboflavin. Interestingly, in the ethanol + sulfate assay, late release of the last was observed, possibly due to the desulfonation reaction of the aromatic structures during the DB22 molecule breakdown. In the case of RE, no improvement was observed with either EDs; and some combinations with the RMs even resulted in decreased color removal. Therefore, the used EDs and RMs showed positive effect on color removal in SEs; but unexpectedly not in REs.

226Ra, 228Ra and 40K in scales from boilers of industrial installations

“…In Northeast, Pernambuco is evidenced by having the second largest garment manufacturer in Brazil [3]. The city of Caruaru is part of this cluster and stands out for its development in textile industries.…”

Impact of Microaeration and the Redox Mediator Anthraquinone‐2,6‐Disulfonate on Azo Dye Reduction and By‐Products Degradation

“…Some works show that the application of quinone‐based compounds, such as anthraquinone‐2‐sulfonate (AQS) and anthraquinone‐2,6‐disulfonate (AQDS), vitamins, such as riboflavin, or even yeast extract can accelerate electron transfer and increase color removal . Biological azo dye reduction usually requires anaerobic operation because the redox condition achieved is more effective for color removal, whereas removal or biodegradation of the by‐products (aromatic amines) occur commonly in aerobic environment, in which the products are used as sources of carbon, nitrogen, and energy …”

Aplicação de aeração intermitente para a degradação de corante azo por consórcio microbiano obtido de florestas tropicais

“…Dentre os corantes, os da classe azo são os mais utilizados no mundo (Amorim et al, 2013;Kunz et al, 2002). Estes compostos possuem grande importância ambiental, já que são de difícil tratabilidade em estações de tratamento de esgoto convencionais, são tóxicos e sua degradação incompleta pode dar origem a aminas aromáticas carcinogênicas (Pinheiro et al, 2004;Singh et al, 2015).…”

“…No processo denominado descoloração redutiva, o azo é reduzido diretamente pela ação de enzimas biológicas, ou indiretamente, na presença de mediadores de óxido-redução (mediador redox, MR) (Singh et al, 2015). Apesar disso, a degradação desses corantes é incompleta nessas condições, tornando necessária a utilização de um pós-tratamento aeróbio para a remoção dos intermediários tóxicos (Amaral et al, 2014;Amorim et al, 2013;Braúna et al, 2009;Gavazza et al, 2015;Imran et al, 2016;Sharma et al, 2016;Talarposhti et al, 2001).…”

“…Os efeitos da concentração inicial de glicose (1 -2 -3 g.L -1 ) e aeração intermitente (0 -4 -8 h.d -1 ) sobre as variáveis respostas descoloração, constante de descoloração (K) e remoção de demanda química de oxigênio (DQO) foram investigados por planejamento fatorial e análise de superfície de resposta. A AR utilizada simulava as características dos efluentes de lavanderias têxteis localizadas no agreste Pernambucano, com base em estudos desenvolvidos por Amaral et al (2017Amaral et al ( , 2014, Amorim et al (2013) (Frota et al, 2014). O governo de São Paulo, em 2017, assinou um decreto que isenta as indústrias do setor têxtil do pagamento do Imposto sobre Circulação de Mercadorias e Serviços em resposta aos benefícios concedidos por outros estados brasileiros, incluindo o Rio de Janeiro e Minas Gerais.…”