Limits of anaerobic biodegradation

Field, Jim A.

doi:10.2166/wst.2002.0276

Cited by 30 publications

(12 citation statements)

References 77 publications

(60 reference statements)

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“…These compounds are characterized by the presence of one or more azo bonds ( N N ), which are responsible for the colour and contribute partially for the recalcitrant nature of the textile effluents. Their resistance to biological degradation in classical activated sludge systems is well documented [4,5].…”

Section: Introductionmentioning

confidence: 99%

The role of adsorption on nanofiltration of azo dyes

Gomes

Gonçalves

Pinho

2005

Journal of Membrane Science

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The influence of osmotic pressure and solute adsorption on permeate flux during nanofiltration (NF) of a wool textile dye solution was investigated. Solutions of C.I. Acid Orange 7 with concentrations ranging from 2 to 2000 mg/l were subjected to nanofiltration with a NF 45 membrane. An increase of flux decline with dye concentration was observed. The resistance-in-series model gives evidence that the main factor causing this flux decline is the solute adsorption. This is reinforced by the increase in the apparent rejection with dye concentration. Although osmotic pressure was taken into account, its contribution to a decrease of the driving force seems not to be significant. Adsorption resistance was calculated from a correlation between the pure water fluxes, measured before and after the essays, and feed dye concentration. A Langmuir isotherm type curve agreed well with experimental data. From the solution-diffusion model, the intrinsic rejection coefficient can be predicted as function of feed dye concentration.

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Section: Introductionmentioning

confidence: 99%

The role of adsorption on nanofiltration of azo dyes

Gomes

Gonçalves

Pinho

2005

Journal of Membrane Science

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“…Another study, observing an autocatalytic effect in the anaerobic reduction of acid orange 7, demonstrated that 1-amino-2-naphthol, one of the dye reduction products, stimulated decolorization (46). The presence of redox mediators in humic substances naturally found in soils has also been reported to enhance decolorization and other redox processes (10,16,23).…”

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confidence: 99%

Characterization of Azo Reduction Activity in a Novel Ascomycete Yeast Strain

Ramalho

Cardoso²,

Cavaco‐Paulo³

et al. 2004

Appl Environ Microbiol

133

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Several model azo dyes are reductively cleaved by growing cultures of an ascomycete yeast species, Issatchenkia occidentalis. In liquid media containing 0.2 mM dye and 2% glucose in a mineral salts base, more than 80% of the dyes are removed in 15 h, essentially under microaerophilic conditions. Under anoxic conditions, decolorization does not occur, even in the presence of pregrown cells. Kinetic assays of azo reduction activities in quasi-resting cells demonstrated the following: (i) while the optimum pH depends on dye structure, the optimum pH range was observed in the acidic range; (ii) the maximum decolorizing activity occurs in the late exponential phase; and (iii) the temperature profile approaches the typical bell-shaped curve. These results indirectly suggest the involvement of an enzyme activity in azo dye reduction. The decolorizing activity of I. occidentalis is still observed, although at a lower level, when the cells switch to aerobic respiration at the expense of ethanol after glucose exhaustion in the culture medium. Decolorization ceased when all the ethanol was consumed; this observation, along with other lines of evidence, suggests that azo dye reduction depends on cell growth. Anthraquinone-2-sulfonate, a redox mediator, enhances the reduction rates of the N,N-dimethylaniline-based dyes and reduces those of the 2-naphthol-based dyes, an effect which seems to be compatible with a thermodynamic factor. The dye reduction products were tested as carbon and nitrogen sources. 1-Amino-2-naphthol was used as a carbon and nitrogen source, and N,N-dimethyl-p-phenylenediamine was used only as a nitrogen source. Sulfanilic and metanilic acids did not support growth either as a carbon or nitrogen source.Over the last two decades, considerable work has been done with the goal of using microorganisms as bioremediation agents in the treatment of wastewater containing textile dyes. These contaminants contribute a minor fraction to the usually high load of dissolved organic matter in textile effluents (35), but they are highly visible and must be removed in order to comply with the regulations concerning effluent discharge.Azo aromatic dyes are the major group of textile dyestuffs. These structures can be reductively cleaved into colorless amines by several bacterial species (for reviews, see references 2, 9, 41, and 43); nevertheless, azo dye reduction occurring in the presence of living matter can be an abiotic process. An example of this is the reduction of acid orange 7 (called dye IV in the present study) and reactive red 2 in anaerobic sludge, where sulfide, produced by sulfate-reducing microorganisms, can reduce azo bonds (45). In most of the reported processes of azo dye bioreduction, however, the participation of an enzymatic activity is assumed. Since the products of azo dye reduction, with few exceptions (4,11,26), cannot be used by bacteria as carbon and energy sources, the cleavage of azo bonds is a gratuitous process which can occur when the microorganisms use a reduced carbon compound as the gro...

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“…Despite the amount of aromatic compounds found in the reactor effluent, no aromatic amines were identified. Some authors state that aromatic amines are the most difficult compounds to degrade in azo dyes reduction (Field 2002;dos Santos et al 2003;Supaka et al 2004;HeFang et al 2004;Plum and Rehorek 2005;Sponza and Isik 2005;van der Zee and Villaverde 2005;Khehra et al 2006;Kumar et al 2006); this indicate that the proposed process is efficient even at high dye concentration (400-500 mg/l). Anaerobic degradation of nitro aromatic compounds or aromatic amines has been demonstrated by other authors (Donlon et al 1996;Kudlich et al 1999;Chen 2002;Chen et al 2006).…”

Section: Resultsmentioning

confidence: 96%

Proposed pathways for the reduction of a reactive azo dye in an anaerobic fixed bed reactor

González-Gutiérrez

González‐Alatorre²,

Escamilla‐Silva

2008

World J Microbiol Biotechnol

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Some process has been proposed for azo dye degradation and anaerobic bioreactors are one of them, since for their reduction, the dye has to be the electron acceptor. An anaerobic fixed bed bioreactor packed with activated carbon (AC) is proposed to degradate the Reactive Red 272 azo dye. In the present paper a dye degradation mechanism in an anaerobic environment is explained. It is very important to consider the interaction dye-microorganism-AC, because the groups in the AC surface take part in the reaction besides being an excellent carrier for microorganism and an adsorbent for the dye. The aromatic compounds produced in the dye reduction are partially degraded as a function of inlet dye concentration and reactor residence time. In anaerobic environment the aromatic compounds are decomposed through hydroxylation, carboxylation and redox reactions, due to enzymatic reactions.

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Limits of anaerobic biodegradation

Cited by 30 publications

References 77 publications

The role of adsorption on nanofiltration of azo dyes

The role of adsorption on nanofiltration of azo dyes

Characterization of Azo Reduction Activity in a Novel Ascomycete Yeast Strain

Proposed pathways for the reduction of a reactive azo dye in an anaerobic fixed bed reactor

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