Potentials of high-temperature anaerobic treatment and redox mediators for the reductive decolorization of azo dyes from textile wastewaters

The discharge of dye-colored wastewaters in surface water represents a serious environmental problem because it may decrease the water transparency, therefore having an effect on photosynthesis, and a public health concern because dyes and their reducing products are carcinogenic. In recent years, big achievements have been made in the use of anaerobic granular sludge not only on colored wastewaters but also on the detoxification of other xenobiotics compounds. This paper compiles some important findings related to the potentials of high-temperature anaerobic treatment and redox mediators on the reductive decolorization of azo dyes from textile wastewaters.

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Catalytic effects of different redox mediators on the reductive decolorization of azo dyes

Water Science & Technology ◽

10.2166/wst.2006.500 ◽

2006 ◽

Vol 54 (2) ◽

pp. 165-170 ◽

Cited By ~ 15

Author(s):

A.A. Encinas-Yocupicio ◽

E. Razo-Flores ◽

F. Sánchez-Díaz ◽

A.B. dos Santos ◽

J.A. Field ◽

...

Keyword(s):

Azo Dyes ◽

Granular Sludge ◽

Order Rate Constant ◽

Anaerobic Treatment ◽

Redox Mediator ◽

Redox Potentials ◽

Redox Mediators ◽

Direct Blue ◽

Reactive Orange ◽

Catalytic Effects

The catalytic effects of redox mediators, with distinct standard redox potentials (E′0), were evaluated on the first-order rate constant of decolorization (Kd) of recalcitrant azo dyes by an anaerobic granular sludge. The dyes studied included mono-azo (Reactive Orange 14, RO14), di-azo (Direct Blue 53, DB53), and tri-azo (Direct Blue 71, DB71) compounds. Toxicity and auto-catalytic aspects seemed to play a role in determining the rate of decolorization. Addition of riboflavin, anthraquinone-2,6-disulphonate (AQDS) or lawsone as a redox mediator, increased the Kd value for all dyes studied, although their impact varied in every case. Kd values were increased from 1.1-fold up to 3.8-fold depending on the redox mediator applied. Moreover, catalysts with moderately similar E′0 value caused distinct stimulation on the rate of decolorization. These results should be considered for selecting the proper redox mediator to be applied during the anaerobic treatment of textile wastewaters and effluents containing electron-withdrawing pollutants, such as nitro-aromatic and polychlorinated compounds.

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Effect of different redox mediators during thermophilic azo dye reduction by anaerobic granular sludge and comparative study between mesophilic (30 °C) and thermophilic (55 °C) treatments for decolourisation of textile wastewaters

Chemosphere ◽

10.1016/j.chemosphere.2004.01.031 ◽

2004 ◽

Vol 55 (9) ◽

pp. 1149-1157 ◽

Cited By ~ 82

Author(s):

André B dos Santos ◽

Iemke A.E Bisschops ◽

Francisco J Cervantes ◽

Jules B van Lier

Keyword(s):

Comparative Study ◽

Azo Dye ◽

Granular Sludge ◽

Anaerobic Granular Sludge ◽

Redox Mediators ◽

Dye Reduction ◽

Textile Wastewaters

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Immobilized Redox Mediators on Anion Exchange Resins and Their Role on the Reductive Decolorization of Azo Dyes

Environmental Science & Technology ◽

10.1021/es9027919 ◽

2010 ◽

Vol 44 (5) ◽

pp. 1747-1753 ◽

Cited By ~ 60

Author(s):

Francisco J. Cervantes ◽

Alberto Garcia-Espinosa ◽

M. Antonieta Moreno-Reynosa ◽

J. Rene Rangel-Mendez

Keyword(s):

Anion Exchange ◽

Azo Dyes ◽

Redox Mediators ◽

Anion Exchange Resins ◽

Exchange Resins ◽

Reductive Decolorization

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Thermophilic treatment by anaerobic granular sludge as an effective approach to accelerate the electron transfer and improve the reductive decolorization of azo dyes in bioreactors

Water Science & Technology ◽

10.2166/wst.2005.0540 ◽

2005 ◽

Vol 52 (1-2) ◽

pp. 363-369 ◽

Cited By ~ 4

Author(s):

A.B. dos Santos ◽

J. Traverse ◽

F.J. Cervantes ◽

J.B. van Lier

Keyword(s):

Electron Transfer ◽

Hydraulic Retention Time ◽

Granular Sludge ◽

Textile Wastewater ◽

Anaerobic Treatment ◽

Significant Difference ◽

Dye Reduction ◽

Effects Of Temperature ◽

Reductive Decolorization ◽

Electron Transfer Capacity

The effects of temperature, hydraulic retention time (HRT), and the redox mediator, anthraquinone-2,6-disulfonate (AQDS), on electron transfer and subsequent reductive decolorization of dyes from textile wastewater was assessed in mesophilic and thermophilic anaerobic bioreactors. The results clearly show that compared to mesophilic anaerobic treatment, thermophilic treatment at 55 °C is an effective approach for increasing the electron transfer capacity in bioreactors, and thus improving the decolorization rates. At an HRT of 2.5 h and in the absence of AQDS, the color removal was 5.3-fold higher at 55 °C compared to 30 °C. Furthermore, similar decolorizations were found at 55 °C between the AQDS-free and AQDS-supplemented reactors, whereas a significant difference (up to 3.6-fold) on dye reduction occurred at 30 °C.

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An Overview of Dementias

Perspectives on Swallowing and Swallowing Disorders (Dysphagia) ◽

10.1044/sasd21.3.75 ◽

2012 ◽

Vol 21 (3) ◽

pp. 75-84

Author(s):

Venkata Vijaya K. Dalai ◽

Jason E. Childress ◽

Paul E Schulz

Keyword(s):

Clinical Presentation ◽

Treatment Options ◽

Current Treatment ◽

Great Variability ◽

Health Concern ◽

Public Health Concern ◽

Life Threatening ◽

The Common ◽

Neurodegenerative Dementias ◽

Made In

Dementia is a major public health concern that afflicts an estimated 24.3 million people worldwide. Great strides are being made in order to better diagnose, prevent, and treat these disorders. Dementia is associated with multiple complications, some of which can be life-threatening, such as dysphagia. There is great variability between dementias in terms of when dysphagia and other swallowing disorders occur. In order to prepare the reader for the other articles in this publication discussing swallowing issues in depth, the authors of this article will provide a brief overview of the prevalence, risk factors, pathogenesis, clinical presentation, diagnosis, current treatment options, and implications for eating for the common forms of neurodegenerative dementias.

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MULTIMET (N-155)

Alloy Digest ◽

10.31399/asm.ad.ss0028 ◽

1961 ◽

Vol 10 (12) ◽

Keyword(s):

High Temperature ◽

Physical Properties ◽

Heat Treating ◽

Age Hardening ◽

Nickel Chromium ◽

Cobalt Nickel ◽

Temperature Performance ◽

High Oxidation ◽

Scaling Resistance ◽

Made In

Abstract MULTIMET alloy is cobalt-nickel-chromium-iron austenitic alloy having high oxidation and scaling resistance along with good high-temperature properties. It tends to work harden but does not respond significantly to age-hardening. It is made in a wrought grade (0.08-0.16% carbon) and a casting grade (0.20% max. carbon). This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep and fatigue. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: SS-28. Producer or source: Haynes Stellite Company. Originally published May 1955, revised December 1961.

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Anaerobic treatment of thermal sludge conditioning liquor with granular sludge

Water Environment Research ◽

10.2175/wer.65.1.2 ◽

1993 ◽

Vol 65 (1) ◽

pp. 6-14 ◽

Cited By ~ 11

Author(s):

Takashi Kimata ◽

Takehiko Kawai ◽

Minoru Tada ◽

Kazuhiro Tanaka ◽

Kazuhiro Shinabe ◽

...

Keyword(s):

Granular Sludge ◽

Anaerobic Treatment ◽

Sludge Conditioning

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Granular sludge bed anaerobic treatment systems for resource recovery

Waste Biorefinery ◽

10.1016/b978-0-12-818228-4.00004-6 ◽

2020 ◽

pp. 107-124

Author(s):

Hamidreza Mojab ◽

Eldon Raj ◽

Santiago Pacheco-Ruiz

Keyword(s):

Granular Sludge ◽

Resource Recovery ◽

Anaerobic Treatment

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Identification of Quinoide Redox Mediators That Are Formed during the Degradation of Naphthalene-2-Sulfonate by Sphingomonas xenophaga BN6

Applied and Environmental Microbiology ◽

10.1128/aem.68.9.4341-4349.2002 ◽

2002 ◽

Vol 68 (9) ◽

pp. 4341-4349 ◽

Cited By ~ 55

Author(s):

Andreas Keck ◽

Jörg Rau ◽

Thorsten Reemtsma ◽

Ralf Mattes ◽

Andreas Stolz ◽

...

Keyword(s):

Azo Dyes ◽

High Performance ◽

Wild Type Strain ◽

Gene Replacement ◽

Redox Mediators ◽

Liquid Chromatography Mass Spectrometry ◽

Anaerobic Conditions ◽

Dioxygenase Gene ◽

Sphingomonas Xenophaga ◽

Culture Supernatants

ABSTRACT During aerobic degradation of naphthalene-2-sulfonate (2NS), Sphingomonas xenophaga strain BN6 produces redox mediators which significantly increase the ability of the strain to reduce azo dyes under anaerobic conditions. It was previously suggested that 1,2-dihydroxynaphthalene (1,2-DHN), which is an intermediate in the degradative pathway of 2NS, is the precursor of these redox mediators. In order to analyze the importance of the formation of 1,2-DHN, the dihydroxynaphthalene dioxygenase gene (nsaC) was disrupted by gene replacement. The resulting strain, strain AKE1, did not degrade 2NS to salicylate. After aerobic preincubation with 2NS, strain AKE1 exhibited much higher reduction capacities for azo dyes under anaerobic conditions than the wild-type strain exhibited. Several compounds were present in the culture supernatants which enhanced the ability of S. xenophaga BN6 to reduce azo dyes under anaerobic conditions. Two major redox mediators were purified from the culture supernatants, and they were identified by high-performance liquid chromatography-mass spectrometry and comparison with chemically synthesized standards as 4-amino-1,2-naphthoquinone and 4-ethanolamino-1,2-naphthoquinone.

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