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Cited by 4Enzyme-mediated dye degradationAdsorption and biosorption for pollutant removalMicrobial bioremediation and biosurfactants

The DOI matches its Crossref record; 136 of the 136 references it cites were found in a registry or an index; none of the 164 sources its claims cite is checked for support yet.

A Review of the Biological Decolorization of Synthetic Azo Dye From Textile Wastewater by Bacterial Strains

Open access
Emadi, Zahra, Sadeghi, Mehraban, Forouzandeh, Solieman·2025·Avicenna Journal of Environmental Health Engineering
DOI 10.34172/ajehe.5491
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Abstract

Artificial dyes are regarded as one of the most problematic environmental pollutants. They are widely applied in the textile, print, paper, paint, pharmaceutical, food, cosmetics, and leather industries. The textile industry produces large volumes of colored wastewater, along with other pollutants such as salts, toxic substances (e.g., heavy metals, biocides, and oxidizing agents), high organic load, nutrients, and sulfur. These dyes adversely affect living organisms and ecosystems by inhibiting photosynthesis and causing health disorders such as skin irritations, allergies, cancer, vomiting, and weakened immune reactions. Thus, they should be removed using physical, chemical, and biological methods. Chemical and physical methods need regeneration processes and chemical agents, and they are expensive. In contrast, bio-decolorization by bacteria, fungi, algae, and plants is an environmentally friendly and cost-effective technique. Bacterial strains can adsorb, degrade, and flocculate dyes. Biodecolorization is positively or negatively affected by operational parameters such as agitation, pH, temperature, dye concentration, carbon and nitrogen sources, salinity, electron donors, and redox mediators. As stated, these parameters have positive (optimum concentration) and negative (beyond optimum) impacts on decolorization efficiency.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

This narrative review summarizes biological decolorization of synthetic azo dyes in textile wastewater, focusing on bacterial strains and their biosorption, biodegradation, and bioflocculation mechanisms. It concludes that bacterial treatment is cost-effective and eco-friendly but is constrained by dye specificity, process optimization needs, and possible toxic intermediates.

Key findings

  • Azo dyes account for about 70% of global dye production; textile wastewater pollutants include salts, organic compounds, heavy metals, and dyes, with dyes visible at concentrations as low as 1 mg/L.
  • Bacterial decolorization occurs mainly through biosorption and biodegradation, with azoreductase and laccase as key enzymes; anaerobic/anoxic steps cleave azo bonds, while aerobic posttreatment can mineralize aromatic amine metabolites.
  • Operational factors strongly affect efficiency: Acid Blue-113 by *Klebsiella* sp. AB-PR was 71% decolorized under static vs 20% under shaking; *Klebsiella* strain Bz4 reached 95.36%, about 90%, and 77.93% under static, semi-static, and shaking conditions, respectively.
  • Temperature, nitrogen, and salinity examples include *Bacillus* sp. CH12 decolorizing Reactive Red-239 at 100% at 30°C but 35% at 45°C; *Shewanella* sp. IFN4 decolorized Direct Red-81 at 99.2% with yeast extract vs 10.9% without; *Bacillus circulans* BWL1061 completely decolorized Methyl Orange at 60 g/L NaCl within 12 hours but below 20% at 80 and 100 g/L NaCl.

Methods

  • Narrative review assessing adverse impacts of the textile industry and treatment methods, including biological decolorization by bacteria, fungi, algae, and plants.
  • Literature was retrieved from Web of Science, PubMed, Google Scholar, and Scopus using keywords/phrases such as natural dye, synthetic dye, textile wastewater, bacteria and decolorization, dye-biosorption and bacteria, dye-degradation and bacteria, and dye-flocculation and bacteria.
  • No time restriction was applied to the literature search; the review synthesizes mechanisms, influencing factors, and examples from cited studies.

Limitations

  • The paper states that bacterial decolorization by pure strains is efficient but dye-specific, making pure strains impractical for real wastewater with complex dye mixtures at large industrial scale; carcinogenic intermediates may be generated, requiring co-culture for detoxification and mineralization.
  • The paper also states that environmental/operational conditions must be optimized, pathogenic strains are a challenge, and the cost and technical feasibility of strain isolation remain controversial compared with conventional biological treatment.
  • Evident from the text: as a narrative review, it does not report a systematic search protocol, inclusion/exclusion criteria, quality appraisal, or quantitative synthesis, and it compares examples from different dyes, strains, and experimental conditions.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.34172/ajehe.5491

Cites

136 of 136 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 164 cited sources checked · 0 supported · 0 flagged

  • Premisenone given

    Laccase (EC 1.10.3.2) is a key non-specific multi-copper oxidative enzyme in the decolorization process.

    “Laccase (EC 1.10.3.2) is a key non-specific multi-copper oxidative enzyme in the decolorization process.”
    Quote in the paperNot a substantial claim
  • Premisecitation

    Under acidic conditions, electrostatic interactions occur between negatively charged dye sites and positively charged protonated biomass functional groups.

    “In the presence of H + ions and under acidic conditions, electrostatic interactions occur between negatively charged dye sites and positively charged biomass sites (protonated functional groups) (122).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [122]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Premisecitation

    The major advantage of anaerobic treatment is the generation of methane gas, a renewable energy source.

    “However, the major advantage of anaerobic treatment is the generation of methane gas, a renewable energy source.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [24]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [60]

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    • cites [61]

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  • Premisecitation

    The blockage of azoreductase active sites directly reduces decolorization efficiency.

    “The blockage of azoreductase active sites directly reduces decolorization efficiency (75).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [75]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Premisecitation

    The decolorization efficiency of Acid Blue-113 by Staphylococcus lentus decreased from 92% to 35% with an increase in dye concentration from 25 to 500 mg/L, respectively.

    “The decolorization efficiency of Acid Blue-113 by Staphylococcus lentus decreased from 92% to 35% with an increase in dye concentration from 25 to 500 mg/L, respectively (134).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [134]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. 33
  • It may state two separate claims as one. 63
  • The quote only partly states this claim. 1

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    Organic compounds applied in textile processes can cause an increase in both biological oxygen demand (BOD) and chemical oxygen demand (COD) in wastewater.

    “Different organic compounds, including enzymes, tallow, sizing materials, organic dyes, and organic acids, are applied in the textile processes, which can cause an increase in both biological oxygen demand (BOD) and chemical oxygen demand (COD) in wastewater (22).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [22]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    Structurally, azo dyes comprise aromatic compounds (e.g., naphthalene and benzene) linked by azo groups (-N=N-).

    “Structurally, azo dyes comprise aromatic compounds (e.g., naphthalene and benzene) linked by azo groups (-N = N-) (19).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [19]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    Azo dyes are the most popular group of synthetic colorants, accounting for about 70% of global dye production.

    “Azo dyes are the most popular group of synthetic colorants, accounting for about 70% of global dye production.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [17]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [18]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    Azo dyes are generally grouped based on the number of azo bonds: mono-, di-, tri-, tetra-, and poly-azo dyes contain one, two, three, four, and more than four azo bonds, respectively.

    “They are generally grouped based on the number of azo bonds in their structure: mono-, dis-, tri-, tetra-, and poly-azo dyes contain one, two, three, four, and more than four azo bonds, respectively (17,18).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [17]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [18]

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  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    Approximately 40-100 g/L of NaNO3 is applied during the dyeing process, as dyes are better fixed on the fibers in the presence of salts.

    “It is reported that approximately 40-100 g/L of NaNO 3 is applied during the dyeing process, as dyes are better fixed on the fibers in the presence of salts (21).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [21]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Interpretationcitation

    Some bacterial strains maintain high efficiency even at higher temperatures, which may be due to the activity of azoreductase enzymes.

    “Additionally, some bacterial strains maintain high efficiency even at higher temperatures, which may be due to the activity of azoreductase enzymes.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Premisecitation

    A halo-alkalithermo-tolerant mixed culture decolorized Direct Red-81 with efficiencies of >90% at 60 °C, >60% at salt concentration up to 5%, and >60% at pH 9 and 10.

    “A halo-alkalithermo-tolerant mixed culture decolorized Direct Red-81 with the efficiencies of > 90% at 60 ° C, > 60% at salt concentration up to 5%, and > 60% at pH 9 and 10 (126).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [126]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    The bio-flocculation activity of Alteromonas sp. CGMCC 10612 reached its maximum at 25 °C but declined with increasing temperature at 30 °C, which can be attributed to reduced bacterial biomass activity.

    “Likewise, the bio-flocculation activity of Alteromonas sp.CGMCC 10612 reached its maximum at 25 ° C but declined with increasing temperature at 30 ° C, which can be attributed to reduced bacterial biomass activity (99).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [99]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Azoreductase remains stable at 60 °C and at 35-40 °C.

    “Pearce et al and Misal and Gawai reported that azoreductase remains stable at 60 ° C and 35-40 ° C, respectively (89,125).”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites Pearce et al

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Misal and Gawai

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [89]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [125]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim.

    Premisecitation

    Bioremediation using potent microorganisms is a safe, cost-effective, and eco-friendly approach to decolorize synthetic dyes from wastewater.

    “Therefore, a safe, cost-effective, and eco-friendly approach, such as bioremediation using potent microorganisms, should be applied to decolorize synthetic dyes from wastewater (38).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [38]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    The decolorization of Reactive Black-5 by Shewanella sp. IFN4 increased with inoculum sizes ranging from 1% to 15%, with faster decolorization rates observed between 1 and 4 hours of incubation.

    “Similarly, the decolorization of Reactive Black-5 by Shewanella sp.IFN4 increased with inoculum sizes ranging from 1% to 15%, with faster decolorization rates observed between 1 and 4 hours of incubation (130).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [130]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    The enzymatic degradation of azo dyes by laccase occurs in several steps: first, the asymmetric breakage of azo groups occurs through laccase activity, followed by subsequent reactions such as deamination, desulfonation, dihydroxylation, and demethylation of the degraded dye molecules.

    “The enzymatic degradation of azo dyes by laccase occurs in several steps.First, the asymmetric breakage of azo groups occurs through laccase activity, followed by subsequent reactions such as deamination, desulfonation, dihydroxylation, and demethylation of the degraded dye molecules (94).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [94]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Insufficient biomass concentration and the unsuitable ratio of biomass (bacterial cells) to dye are key factors contributing to reduced decolorization efficiency.

    “Insufficient biomass concentration and the unsuitable ratio of biomass (bacterial cells) to dye are key factors contributing to reduced decolorization efficiency (133).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [133]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisenone given

    Bio-flocculants are natural polymeric macromolecules, including proteins, lipids, glycoproteins, nucleic acids, and polysaccharides, produced by microorganisms.

    “Bio-flocculants are natural polymeric macromolecules, including proteins, lipids, glycoproteins, nucleic acids, and polysaccharides, produced by microorganisms.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Premisecitation

    The decolorization efficiency of Reactive Blue EFAF by Exiguobacterium profundum strain CMR2 increased from 65% to 80% as inoculum size rose from 0.25 to 1 mL, but declined from 80% to 77% when inoculum size further increased from 1 to 1.5 mL.

    “For instance, the decolorization efficiency of Reactive Blue EFAF by Exiguobacterium profundum strain CMR2 increased from 65% to 80% as inoculum size rose from 0.25 to 1 mL, but declined from 80% to 77% when inoculum size further increased from 1 to 1.5 mL (129).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [129]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    High temperature causes fiber swelling, which facilitates the penetration of dye auxiliary groups into the fiber's internal structure and enhances dye-fiber bonding.

    “High temperature causes fiber swelling, which facilitates the penetration of dye auxiliary groups into the fiber's internal structure and enhances dye-fiber bonding (27).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [27]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • The quote only partly states this claim.

    Interpretationcitation

    Decolorization efficiencies of Reactive Red-239 by Bacillus sp. strain CH12 were diminished with an increase in temperature.

    “As a result, decolorization efficiencies were diminished with an increase in temperature (123).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [123]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Interpretationcitation

    High dye concentrations can suppress bacterial growth and block the active sites of key enzymes involved in decolorization, especially azoreductase.

    “High dye concentrations can suppress bacterial growth and block the active sites of key enzymes involved in decolorization, especially azoreducatse.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.

    Interpretationreasoning

    Increasing temperature increases adsorption capacity because the kinetic energy of the solute and surface activity increase with temperature.

    “Increasing temperature increases adsorption capacity because the kinetic energy of the solute and surface activity increase with temperature.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Increasing temperature increases adsorption capacity because the kinetic energy of the solute and surface activity increase with temperature.

  • It may state two separate claims as one.

    Premisereasoning

    Shaking increases the concentration of dissolved oxygen, and both oxygen and azo bonds act as electron acceptors; oxygen receives electrons as a preferred acceptor, preventing electron transfer to azo bonds, thereby reducing azo bonds and decreasing decolorization efficiency.

    “Shaking increases the concentration of dissolved oxygen, and both oxygen and azo bonds act as electron acceptors.Oxygen receives electrons as a preferred acceptor, preventing electron transfer to azo bonds, thereby reducing azo bonds and decreasing decolorization efficiency.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Premisecitation

    Aerobic treatment of colored wastewater occurs in the presence of oxygen and is not an efficient technique, especially for azo dyes because oxygen competes with azo bonds as an electron acceptor.

    “However, the aerobic treatment of colored wastewater occurs in the presence of oxygen and is not an efficient technique, especially for azo dyes because oxygen competes with azo bonds as an electron acceptor (24,60,61).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [24]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [60]

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    • cites [61]

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  • It may state two separate claims as one.

    Interpretationreasoning

    An increase in dye concentration in the culture medium generally diminishes decolorization efficiency, which can be attributed to the toxic nature of dye molecules and the inhibitory influence of intermediates and by-products formed during biological decolorization.

    “An increase in dye concentration in the culture medium generally diminishes decolorization efficiency, which can be attributed to the toxic nature of dye molecules and the inhibitory influence of intermediates and by-products formed during biological decolorization.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisenone given

    Fungal species produce intracellular and extracellular lignin-modifying enzymes, including manganese peroxidase (MnP), laccase (Lac), and lignin peroxidase (LiP), which contribute to dye decolorization.

    “Fungal species produce intracellular and extracellular lignin-modifying enzymes, including manganese peroxidase (MnP), laccase (Lac), and lignin peroxidase (LiP), which contribute to dye decolorization.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    The presence of dyes in water bodies is particularly undesirable, as they remain visible in aquatic media even at low concentrations (1 mg/L).

    “The presence of dyes in the water bodies is particularly undesirable, as they remain visible in aquatic media even at low concentrations (1 mg/L) (12,28).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [12]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [28]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Azoreductase is sensitized to oxygen and acts efficiently under anaerobic or microaerophilic conditions (oxygen-sensitive azoreductase).

    “Azoreductase is sensitized to oxygen and acts efficiently under anaerobic or microaerophilic conditions (oxygen-sensitive azoreductase) (85,86).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [85]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [86]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    Consumption of sodium hydroxide in the textile industry leads to the generation of slightly alkaline wastewater.

    “In addition, the consumption of sodium hydroxide in the textile industry (e.g., mercerizing, washing, and scouring) leads to the generation of slightly alkaline wastewater (23).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds. It may state two separate claims as one.

    Premisenone given

    Cationic dyes are adsorbed by carboxyl and other negatively charged functional groups, while anionic dyes are adsorbed by amine functional groups through hydrogen and electrostatic bonding.

    “Reports indicate that cationic dyes are adsorbed by carboxyl and other negatively charged functional groups, while anionic dyes are adsorbed by amine functional groups through hydrogen and electrostatic bonding.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Premisecitation

    The decolorization efficiencies of Azobenzene, Methyl Red, Orange G, and Congo Red by Bacillus subtilis increased from 9.61 to 17.68%, 62.41 to 78.49%, 6.83 to 22.54%, and 54.24 to 71.28%, respectively, as the temperature increased from 25 to 45 °C.

    “The decolorization efficiencies of Azobenzene, Methyl Red, Orange G, and Congo Red by Bacillus subtilis increased from 9.61 to 17.68%, 62.41 to 78.49%, 6.83 to 22.54%, and 54.24 to 71.28%, respectively, as the temperature increased from 25 to 45 ° C (88).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [88]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Carbon sources act as electron donor agents and are necessary for the reduction and cleavage of azo bonds.

    “They also act as electron donor agents and are necessary for the reduction and cleavage of azo bonds (136).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [136]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Azoreductase (EC 1.7.1.6) is a specific enzyme involved in azo dye decolorization and is found in both eukaryotic and prokaryotic organisms.

    “Azoreductase (EC 1.7.1.6)is a specific enzyme involved in azo dye decolorization and is found in both eukaryotic and prokaryotic organisms (84).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [84]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Algae do not require external supplements for decolorization, while bacteria and fungi require additional supplements.

    “Algae do not require external supplements for decolorization, while bacteria and fungi require additional supplements (34).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [34]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    Textile wastewater causes changes in productivity, fertility, and nutrient supply of plants due to surfactants, changes in plant sensitivity to various pathogens, and detrimental impacts on chlorophyll content.

    “Changes in productivity, fertility, and nutrient supply of plants due to surfactants in textile wastewater, changes in plant sensitivity to various pathogens, and detrimental impacts on chlorophyll content (31,32)”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [31]

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    • cites [32]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Biological decolorization is an environmentally friendly technique that is generally less costly than other methods.

    “Biological decolorization is an environmentally friendly technique that is generally less costly than other methods.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [60]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    One of the main limitations of chemical oxidation is its high cost, which cannot be supplied in all areas and countries, especially in low-income countries.

    “However, one of the main limitations of chemical oxidation is its high cost (33,34), which cannot be supplied in all areas and countries, especially in low-income countries.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [33]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [34]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Complete degradation and destruction of dyes do not happen through anaerobic treatment; instead, dyes are transformed into colorless aromatic amine intermediates (monocyclic or polycyclic), which are toxic and require supplementary post-treatment such as aerobic or chemical oxidation techniques.

    “However, complete degradation and destruction of dyes do not happen through anaerobic treatment.Instead, dyes are transformed into colorless aromatic amine intermediates (monocyclic or polycyclic), which are toxic and require supplementary post-treatment such as aerobic or chemical oxidation techniques.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [24]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [60]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [61]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    The optimal pH and temperature for azoreductase generally range from 5-9 and 25-85 °C, respectively.

    “The optimal pH and temperature for azoreductase generally range from 5-9 and 25-85 ° C, respectively (89).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [89]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisenone given

    Various parameters influence bacterial decolorization efficiency.

    “Various parameters influence bacterial decolorization efficiency.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Premisenone given

    Dye decolorization occurs through biosorption onto biomass and biodegradation within cells.

    “Dye decolorization occurs through biosorption onto biomass and biodegradation within cells.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Premisecitation

    The maximum adsorption capacity (150 mg/g) of Reactive Black-5 by Corynebacterium glutamicum was observed at pH 1, after which the capacity declined to less than 50 mg/g at pH 6 and 7.

    “Vijayaraghavan and Yun reported that the maximum adsorption capacity (150 mg/g) of Reactive Black-5 (an anionic dye) by Corynebacterium glutamicum was observed at pH 1, after which the capacity declined (to less than 50 mg/g) at pH 6 and 7.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Vijayaraghavan and Yun

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper may give no reason why it holds.

    Interpretationnone given

    Pollutants in textile wastewater exert adverse and harmful impacts on the environment and living organisms.

    “Pollutants in textile wastewater exert adverse and harmful impacts on the environment and living organisms.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    The pH of textile wastewater ranges from neutral to alkaline values, as dyeing processes with different dyes are carried out under various pH values.

    “The pH of textile wastewater ranges from neutral to alkaline values, as dyeing processes with different dyes are carried out under various pH values (reactive dyes are treated under alkaline conditions) (21).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [21]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisenone given

    Biological treatment of azo dyes can be carried out using various organisms, including fungi, algae, plants, and bacteria.

    “The biological treatment of azo dyes can be carried out using various organisms, including fungi, algae, plants, and bacteria (described in detail in this review).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisenone given

    Bio-flocculation occurs through different mechanisms: initially, charge neutralization and patching take place, followed by hydrogen bonding and polymer bridging.

    “Bio-flocculation occurs through different mechanisms.Initially, charge neutralization and patching take place, followed by hydrogen bonding and polymer bridging.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Premisecitation

    Both membrane filtration and adsorption produce secondary wastes that require additional treatment.

    “However, both methods produce secondary wastes that require additional treatment (35)(36)(37).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites (35)(36)(37)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. It may be too vague to check against evidence. The paper may give no reason why it holds.

    Interpretationreasoning

    Given the deleterious effects of textile wastewater containing dyes, it is essential to treat these effluents before their discharge into the environment.

    “Given the deleterious effects of textile wastewater containing dyes, it is essential to treat these effluents before their discharge into the environment.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Premisecitation

    Bacterial strains utilize dyes as the sole carbon source for providing energy, which can influence the growth and activity of strains.

    “In this case, bacterial strains utilize dyes as the sole carbon source for providing energy, which can influence the growth and activity of strains (135).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [135]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    The produced aromatic amine metabolites are nonbiodegradable and cannot be further degraded under anaerobic conditions, leading to persistent COD in the treated wastewater.

    “Because of the nonbiodegradable characteristic of the produced aromatic amine metabolites, they cannot be further degraded in the decolorized solution under anaerobic conditions, and this leads to persistent COD in the treated wastewater.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [24]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [60]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [61]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    Heavy metals have neurological and carcinogenic effects.

    “It should be noted that heavy metals have neurological and carcinogenic effects (25,26).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [25]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [26]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.

    Premisenone given

    Bio-remediation of pollutants by plants (phytoremediation) is considered a sustainable and cost-effective technique.

    “Bio-remediation of pollutants by plants (phytoremediation) is considered a sustainable and cost-effective technique.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Premisecitation

    Phytoremediation has several limitations, including the accumulation of pollutants in the edible parts of plants, reduced plant biomass in the presence of pollutants, the need for continuous cultivation and harvesting to achieve efficient decontamination, long treatment duration, dependence on seasonal variations, and disposal and management of phytoremediators.

    “However, phytoremediation has several limitations, including the accumulation of pollutants in the edible parts of plants, reduced plant biomass in the presence of pollutants, the need for continuous cultivation and harvesting to achieve efficient decontamination, long treatment duration, dependence on seasonal variations, and disposal and management of phytoremediators (73).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [73]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    The growth and metabolic activity of microorganisms, as well as enzyme activity, are affected by pH.

    “The growth and metabolic activity of microorganisms, as well as enzyme activity, are affected by pH (113).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [113]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Decolorization efficiencies of Congo Red, Direct Black, and Methylene Blue increased with higher inoculum dosage of Alteromonas sp. CGMCC 10612 bio-flocculants, as higher inoculum dosages provides a larger surface area and more adsorption sites.

    “Decolorization efficiencies of Congo Red, Direct Black, and Methylene Blue increased with higher inoculum dosage of Alteromonas sp.CGMCC 10612 bio-flocculants, as higher inoculum dosages provides a larger surface area and more adsorption sites (99).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [99]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisenone given

    Compared to chemical flocculants, bio-flocculants are non-toxic and biodegradable.

    “Compared to chemical flocculants, bio-flocculants are non-toxic and biodegradable.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Premisecitation

    The flocculation activity of Methylobacterium sp. Obi and Actinobacterium sp. mayor consortium increased when the inoculum size increased from 0.5% to 1% v/v, and then reduced when the inoculum size rose from 1% to 2%.

    “However, the flocculation activity of Methylobacterium sp.Obi and Actinobacterium sp.mayor consortium increased when the inoculum size increased from 0.5% to 1% v/v, and then reduced when the inoculum size rose from 1% to 2%.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [131]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    In the presence of salts, water molecules inside the structure of microbial cells move into external environments, leading to the prohibition of microbial growth and cell death.

    “In the presence of salts, water molecules inside the structure of microbial cells move into external environments, leading to the prohibition of microbial growth and cell death (143).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [143]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Flocculation activity increased from 0 to 1300 U/mL as glucose concentration rose from 0 to 30 g/L, but decreased at higher glucose concentrations (above 30 g/L).

    “Flocculation activity increased from 0 to 1300 U/mL as glucose concentration rose from 0 to 30 g/L, but decreased at higher glucose concentrations (above 30 g/L) (99).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [99]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    The individual application of peptone and yeast extract (nitrogen sources) showed the best efficiency in the decolorization process, whereas efficiency declined with the combined application of carbon and nitrogen sources in the culture medium.

    “The individual application of peptone and yeast extract (nitrogen sources) showed the best efficiency in the decolorization process, whereas efficiency declined with the combined application of carbon and nitrogen sources in the culture medium.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [146]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Catalytic breakage of maltose leads to the generation of electrons, which are then transferred to the azo bonds of dyes by the redox mediators.

    “Catalytic breakage of maltose leads to the generation of electrons, which are then transferred to the azo bonds of dyes by the redox mediators.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [137]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    The mechanism of salt tolerance in microorganisms is often associated with the accumulation of osmolytes.

    “The mechanism of salt tolerance in microorganisms is often associated with the accumulation of osmolytes.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [152]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Microorganisms cannot utilize dyes, but the presence of a co-substrate such as electron donor groups in the colored culture medium promotes the catabolism of chromophore groups.

    “Consequently, microorganisms cannot utilize dyes, but the presence of a co-substrate such as electron donor groups in the colored culture medium, promotes the catabolism of chromophore groups (62).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [62]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    The application of agricultural products instead of commercial and pure substrates like beef extract, peptone, and yeast extract is low-priced, economical, and environmentally friendly.

    “The application of agricultural products instead of commercial and pure substrates like beef extract, peptone, and yeast extract is low-priced, economical, and environmentally friendly (149).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [149]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    Some microorganisms utilize dyes as the sole nitrogen and carbon sources.

    “Moreover, some microorganisms utilize dyes as the sole nitrogen and carbon sources (138).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [138]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Interpretationreasoning

    Attention has been drawn to the use of biological methods due to factors such as the lack of chemical substance consumption, no need for regeneration as in adsorbent-based methods, and fewer controversial operational difficulties such as fouling seen in membrane technologies.

    “Due to factors such as the lack of chemical substance consumption (e.g., oxidants), no need for regeneration as in adsorbent-based methods, and fewer controversial operational difficulties, such as fouling, seen in membrane technologies, attention has been drawn to the use of biological methods.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Premisecitation

    Yeast extract plays a crucial role in the generation of reducing agents (NADH and NADPH), which act as electron carriers in the reduction of dyes and accelerate azoreductase activity.

    “Yeast extract plays a crucial role in the generation of reducing agents (NADH and NADPH), which can act as electron carriers in the reduction of dyes and accelerate azoreductase activity (147).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [147]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Mixed bacterial strains demonstrated 86%, 95%, 91%, 85%, and 84% decolorization efficiencies for Red RB, Remazol Red, Remazol Blue, Remazol Violet, Remazol Orange, and Remazol Yellow in the presence of starch as optimum carbon co-substrate, respectively.

    “Mixed bacterial strains demonstrated 86%, 95%, 91%, 85%, and 84% decolorization efficiencies for Red RB, Remazol Red, Remazol Blue, Remazol Violet, Remazol Orange, and Remazol Yellow in the presence of starch as optimum carbon co-substrate, respectively (139).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [139]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    Microorganisms are categorized as moderately halophilic (0.5-3.5 M NaCl) or extremely halophilic (>3.5 M NaCl).

    “Microorganisms are categorized as moderately halophilic (0.5-3.5 M NaCl) or extremely halophilic ( > 3.5 M NaCl) (85).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [85]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    Carbon sources such as glucose increase the growth and biomass concentration of microorganisms, which leads to an increase in dye adsorption on the cell surface.

    “Carbon sources such as glucose increase the growth and biomass concentration of microorganisms, which leads to an increase in dye adsorption on the cell surface (140).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [140]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    High concentrations of salts impact osmotic pressure, plasmolysis, microbial growth, and enzymatic metabolisms.

    “High concentrations of salts impact osmotic pressure, plasmolysis, microbial growth, and enzymatic metabolisms.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [143]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    The presence of co-substrate (carbon and nitrogen sources) in the microbial culture medium enhances bacterial growth and respiration, leading to a decline in oxygen concentration (optimum condition for reducing azo dyes by azoreductase enzymes).

    “The presence of co-substrate (carbon and nitrogen sources) in the microbial culture medium enhances bacterial growth and respiration, leading to a decline in oxygen concentration (optimum condition for reducing azo dyes by azoreductase enzymes) (107).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [107]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Interpretationreasoning

    Salt-tolerant microorganisms can treat saline textile wastewater directly at industrial sites without pretreatment, making the process more economical and beneficial.

    “Conversely, salt-tolerant microorganisms can treat saline textile wastewater directly at industrial sites without pretreatment, making the process more economical and beneficial.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Textile wastewater often contains high salt concentrations (about 60-100 g/L).
    • Rests on an assumption: Pre-treatment processes such as dilution with fresh water, electrodialysis, and reverse osmosis are costly and increase the volume of wastewater.
    • Rests on an assumption: Sodium hydroxide, commonly used to enhance dyeing performance in the dye bath, increases the pH (almost up to 10), sodium concentrations, and overall salinity in wastewater.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisenone given

    Cationic ions are commonly applied as additives in the bio-flocculation process.

    “Cationic ions are commonly applied as additives in the bio-flocculation process.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Premisecitation

    Activated carbon has a quinone structure on its surface, which can enhance the decolorization efficiency of dyes.

    “Activated carbon has a quinone structure on its surface, which can enhance the decolorization efficiency of dyes (160).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [160]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    Methanol is broadly applied as a cost-effective electron donor in wastewater treatment plants.

    “Methanol is broadly applied as a cost-effective electron donor in wastewater treatment plants (157).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [157]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.

    Interpretationreasoning

    Molasses consumption as a carbon source is efficient in bioremediation.

    “Molasses consumption as a carbon source is efficient in bioremediation.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Premisereasoning

    Nitrate and nitrite act as electron receptors and compete with azo bonds for electron transfer.

    “Nitrate and nitrite act as electron receptors and compete with azo bonds for electron transfer.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Interpretationnone given

    Carbon sources are essential for cell growth and bio-flocculant production.

    “Carbon sources are essential for cell growth and bio-flocculant production.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Interpretationreasoning

    The biological approach is cost-effective and involves fewer operational difficulties if managed properly.

    “This approach is cost-effective and involves fewer operational difficulties if managed properly.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    Molasses is easily accessible, inexpensive, and easy to store.

    “Molasses is easily accessible, inexpensive, and easy to store (142).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [142]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Premisecitation

    The decolorization efficiencies of Erythrosine B by anaerobic granular sludge were 38% with lactose, 36% with glucose, and 17% with volatile fatty acids.

    “The decolorization efficiencies were 38% (lactose), 36% (glucose), and 17% (volatile fatty acids).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Apostol et al

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim. It may be too vague to check against evidence.

    Interpretationreasoning

    Isolation, identification, and application of potent bacterial strains for textile wastewater treatment is a promising and efficient technique.

    “Since conventional wastewater treatment systems cannot remove dyes and other complex organic substances, the isolation, identification, and application of potent bacterial strains for textile wastewater treatment is a promising and efficient technique.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Conventional wastewater treatment systems cannot remove dyes and other complex organic substances.

  • It may state two separate claims as one.

    Interpretationcitation

    It is a cost-effective technique that can be applied in various countries.

    “Thus, it is a costeffective technique that can be applied in various countries (157).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [157]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • It may state two separate claims as one.

    Interpretationnone given

    Bacterial decolorization of azo dyes by pure strains is efficient but is specific to each dye.

    “Bacterial decolorization (as the most popular applied microorganisms) of azo dyes by pure strains is efficient, but it is specific to each dye.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. It may be too vague to check against evidence.

    Interpretationreasoning

    Identifying the optimum range of operational factors is essential to improve the effectiveness of bacterial decolorization.

    “Therefore, identifying the optimum range of these factors is essential to improve the effectiveness of bacterial decolorization.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Bio-decolorization is influenced by operational factors such as agitation, pH, temperature, dye concentration, inoculum size, carbon source, nitrogen source, salinity, redox mediator, and electron donor compounds.
    • Rests on an assumption: These operational factors have positive impacts at their optimum levels, but beyond these levels, negative impacts may be observed.
    • Rests on an assumption: These factors affect the growth and activity of bacterial strains, particularly enzyme production and function, including azoreductase and lacasse.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Interpretationreasoning

    Factors such as pathogenic strains and the cost/technical feasibility of strain isolation may limit the application of biological processes at full scale, but can be minimized by an engineering-based approach.

    “These factors may limit the application of biological processes at fullscale, but they can be minimized by an engineering-based approach.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Pathogenic strains are a challenging complication in bioremediation.

  • It may state two separate claims as one.

    Interpretationnone given

    The biological approach treats wastewater under both aerobic and anaerobic conditions and is considered a source of energy generation under anaerobic conditions, which reduces energy production costs.

    “The biological approach treats wastewater under both aerobic and anaerobic conditions (unlike other methods) and is also considered a source of energy generation under anaerobic conditions, which reduces energy production costs.”
    Quote in the paperSubstantial claim
85 of 85

  • The paper relies on this without support.

    Discharge of wastewater containing chlorine salts into water environments reduces dissolved oxygen levels.

    “When wastewater containing chlorine salts is discharged into the water environments, it reduces dissolved oxygen levels.”

  • The paper relies on this without support.

    The aromatic structure and synthetic origins of artificial dyes make their decolorization process complicated.

    “The aromatic structure and synthetic origins of artificial dyes make their decolorization process complicated.”

  • The paper relies on this without support.

    High and low temperatures prevent microorganisms' growth and enzymatic activity involved in dye decolorization.

    “High and low temperatures prevent microorganisms' growth and enzymatic activity involved in dye decolorization.”

  • The paper relies on this without support.

    The reduction in decolorization efficiency at higher temperatures is mainly due to the loss of cell viability.

    “The reduction in decolorization efficiency at higher temperatures is mainly due to the loss of cell viability.”

  • The paper relies on this without support.

    The activity of enzymes responsible for decolorization (e.g., azoreductase) diminishes at higher temperatures because of enzyme denaturation.

    “Moreover, the activity of enzymes responsible for decolorization (e.g., azoreductase) diminishes at higher temperatures because of enzyme denaturation.”

  • The paper relies on this without support.

    Increasing temperature increases adsorption capacity because the kinetic energy of the solute and surface activity increase with temperature.

    “Increasing temperature increases adsorption capacity because the kinetic energy of the solute and surface activity increase with temperature.”

  • The paper relies on this without support.

    Azoreductase is the most important enzyme in the degradation and decolorization of azo dyes.

    “Azoreductase is the most important enzyme in the degradation and decolorization of azo dyes.”

  • The paper relies on this without support.

    Riboflavin, thiamine, and pyridoxine are the main components of yeast extract, and they impact the growth and activity of microbial strains.

    “Riboflavin, thiamine, and pyridoxine are the main components of yeast extract, and they impact the growth and activity of microbial strains.”

  • The paper relies on this without support.

    Experimental results demonstrated that the individual application of these components was not effective in the decolorization process.

    “Experimental results demonstrated that the individual application of these components was not effective in the decolorization process.”

  • The paper relies on this without support.

    The pKa of amine is about 8.5, so amino groups carry a positive charge at pH < 7.

    “The pKa of amine is about 8.5, and thus the amino groups carry a positive charge at pH < 7.”

  • The paper relies on this without support.

    Carboxyl groups have a pKa of about 3.6-4.5 and are negatively charged at pH > 4.

    “Carboxyl groups, with a pKa of about 3.6-4.5,have negative charges at pH > 4.”

  • The paper relies on this without support.

    Carbon sources supply energy for the growth and survival of microorganisms.

    “Carbon sources supply energy for the growth and survival of microorganisms.”

  • The paper relies on this without support.

    Textile wastewater often contains high salt concentrations (about 60-100 g/L).

    “Textile wastewater often contains high salt concentrations (about 60-100 g/L).”

  • The paper relies on this without support.

    Vitamins and amino acids from organic nitrogen sources are critical factors in bio-flocculant production.

    “Vitamins and amino acids from organic nitrogen sources are critical factors in bio-flocculant production.”

  • The paper relies on this without support.

    Pre-treatment processes such as dilution with fresh water, electrodialysis, and reverse osmosis are costly and increase the volume of wastewater.

    “However, these methods are costly and increase the volume of wastewater.”

  • The paper relies on this without support.

    Sodium hydroxide, commonly used to enhance dyeing performance in the dye bath, increases the pH (almost up to 10), sodium concentrations, and overall salinity in wastewater.

    “Sodium hydroxide, commonly used to enhance dyeing performance in the dye bath, increases the pH (almost up to 10), sodium concentrations, and overall salinity in wastewater.”

  • The paper relies on this without support.

    Due to the toxicity of dyes, microbial growth and activity are often limited.

    “Due to the toxicity of dyes, microbial growth and activity are often limited.”

  • The paper relies on this without support.

    High nitrogen concentrations in treated wastewater cause eutrophication in the aquatic environment.

    “High nitrogen concentrations in the treated wastewater cause eutrophication in the aquatic environment.”

  • The paper relies on this without support.

    Some carcinogenic intermediates may be generated during the bioremediation of dyes using bacterial strains.

    “In addition, some carcinogenic intermediates may be generated during the bioremediation of dyes using bacterial strains.”

  • The paper relies on this without support.

    Pathogenic strains are a challenging complication in bioremediation.

    “Pathogenic strains are another challenging complication in bioremediation.”

  • The paper relies on this without support.

    Synthetic dyes are extensively applied in different industries due to their stability against light and detergents, a wide range of colors, and ease of production.

    “Synthetic dyes are extensively applied in different industries due to their stability against light and detergents, a wide range of colors, and ease of production.”

  • The paper relies on this without support.

    The textile industry is one of the largest consumers of dyes among all industries.

    “The textile industry is one of the largest consumers of dyes among all industries.”

  • The paper relies on this without support.

    The textile industry contains toxic substances (dyes, heavy metals such as Cr, As, Cd, Pb, Ni, and Hg, biocides, surfactants, starch, and oxidizing agents) and has high BOD, COD, total dissolved solids, total suspended solids, and electrical conductivity.

    “The textile industry contains toxic substances (dyes, heavy metals such as Cr, As, Cd, Pb, Ni, and Hg, biocides, surfactants, starch, and oxidizing agents) and has high BOD, COD, total dissolved solids, total suspended solids, and electrical conductivity.”

  • The paper relies on this without support.

    Azo dyes are the most widely used group of dyes in the textile industry.

    “Azo dyes are the most widely used group of dyes in the textile industry.”

  • The paper relies on this without support.

    The presence of these dyes has adverse effects on water quality (e.g., reduced photosynthesis and anoxic conditions) and can cause serious health complications in humans (e.g., cancer, allergy, and irritation).

    “The presence of these dyes has adverse effects on water quality (e.g., reduced photosynthesis and anoxic conditions) and can cause serious health complications in humans (e.g., cancer, allergy, and irritation).”

  • The paper relies on this without support.

    Physical methods such as RO and NF nanofiltration are costly and generate secondary pollutants that need additional treatment.

    “Physical methods such as RO and NF nanofiltration are costly and generate secondary pollutants that need additional treatment.”

  • The paper relies on this without support.

    Chemical treatment methods require large amounts of chemicals, leading to high costs.

    “Chemical treatment methods require large amounts of chemicals, leading to high costs.”

  • The paper relies on this without support.

    Biological treatment is considered cost-effective and environmentally friendly.

    “Biological treatment is considered cost-effective and environmentally friendly.”

  • The paper relies on this without support.

    Bio-decolorization can be carried out by different living organisms (bacteria, yeast, algae, fungi, and plants).

    “Bio-decolorization can be carried out by different living organisms (bacteria, yeast, algae, fungi, and plants).”

  • The paper relies on this without support.

    Bacterial strains are extensively applied for biodecolorization due to their broad distribution and high adaptability.

    “Bacterial strains are extensively applied for biodecolorization due to their broad distribution and high adaptability.”

  • The paper relies on this without support.

    Conventional wastewater treatment systems cannot remove dyes and other complex organic substances.

    “conventional wastewater treatment systems cannot remove dyes and other complex organic substances”

  • The paper relies on this without support.

    Azo dyes should be treated under anaerobic and anoxic conditions for the breakage of azo bonds, followed by further degradation and detoxification (oxidative mechanisms) under aerobic or advanced oxidation processes.

    “At first, azo dyes should be treated under anaerobic and anoxic conditions for the breakage of azo bonds, followed by further degradation and detoxification (oxidative mechanisms) under aerobic or advanced oxidation processes.”

  • The paper relies on this without support.

    Reductive and oxidative degradation of azo dyes occurs through the action of azoreductase and laccase enzymes, respectively.

    “Reductive and oxidative degradation of azo dyes occurs through the action of azoreductase and laccase enzymes, respectively.”

  • The paper relies on this without support.

    Bio-decolorization is influenced by operational factors such as agitation, pH, temperature, dye concentration, inoculum size, carbon source, nitrogen source, salinity, redox mediator, and electron donor compounds.

    “It should be noted that bio-decolorization is influenced by operational factors such as agitation, pH, temperature, dye concentration, inoculum size, carbon source, nitrogen source, salinity, redox mediator, and electron donor compounds.”

  • The paper relies on this without support.

    These operational factors have positive impacts at their optimum levels, but beyond these levels, negative impacts may be observed.

    “These operational factors have positive impacts at their optimum levels, but beyond these levels, negative impacts may be observed.”

  • The paper relies on this without support.

    These factors affect the growth and activity of bacterial strains, particularly enzyme production and function, including azoreductase and lacasse.

    “These factors affect the growth and activity of bacterial strains, particularly enzyme production and function, including azoreductase and lacasse.”

  • The paper relies on this without support.

    Optimizing environmental and operational conditions (pH, temperature, dye concentration) improves bioremediation efficiency for different microbial strains.

    “Environmental and operational conditions, such as pH, temperature, and dye concentration, should be optimized to improve bioremediation efficiency regarding different microbial strains.”

  • The paper relies on this without support.

    Bacterial decolorization can occur under aerobic, anoxic, and anaerobic conditions.

    “Bacterial decolorization can occur under aerobic, anoxic, and anaerobic conditions.”
38 of 38

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Temperature trend contradicts the listed efficiencies

    Minor

    The efficiencies rise from 40% at 15 °C to 100% at 30 °C before falling. They therefore did not simply diminish as temperature increased.

  • Claimed maximum flocculation activity is lower than later values

    Minor

    The stated maximum of 66% for Bacillus subtilis 35A is below the subsequently reported 70-78% range for the same bio-flocculant at higher yeast-extract concentrations.

2 of 2

Citations

Cites

Flagged first, then by citations

Research works printed but not linked: 16

  1. Chaudhary B, Violet T. Chemistry of synthetic dyes: a review. J Interdiscipl Cycle Res. 2020;12(390):390-6.
  2. da Costa Ferreira Ramalho PA. Degradation of Dyes with Microorganisms: Studies with Ascomycete Yeasts [dissertation]. Braga: University of Minho; 2005.
  3. Zollinger H. Color Chemistry: Syntheses, Properties, and Applications of Organic Dyes and Pigments. John Wiley & Sons; 2003.
  4. Gosavi VD, Sharma S. A general review on various treatment methods for textile wastewater. Journal of Environmental Science, Computer Science and Engineering & Technology. 2014;3(1):29-39.
  5. Hatami Manesh M, Mirzayi M, Bandegani M, Sadeghi M, Sabet F. Determination of mercury, lead, arsenic, cadmium and chromium in salt and water of Maharloo Lake, Iran, in different seasons. J Mazandaran Univ Med Sci. 2013;23(108):91-8. [Persian].
  6. Sadeghi M, Rahimi R, Mohammadi-Moghadam F, Mengelizadeh N. Using ash prepared from almond shell for removing acid red 18 from aqueous solutions. J Shahrekord Univ Med Sci. 2017;19(1):126-36. [Persian].
  7. Sadeghi M, Karimi H, Hadi Alijanvand M. Removal of lead ions from industrial wastewater using precipitation process. Environ Eng Manag J. 2017;16(7):1563-8.
  8. Puvaneswari N, Muthukrishnan J, Gunasekaran P. Toxicity assessment and microbial degradation of azo dyes. Indian J Exp Biol. 2006;44(8):618-26.
  9. Kalra SS, Mohan S, Sinha A, Singh G. Advanced oxidation processes for treatment of textile and dye wastewater: a review. In: 2nd International Conference on Environmental Science and Development. Singapore: IACSIT Press; 2011.
  10. Mahmoodi A, Mehdinia SM, Rahmani A, Nassehinia H. Investigation efficiency of nano photocatalytic compound of TiO2 and rice husk silica in removal of reactive red 198 dye from synthetic aqueous solutions. Iran J Catal. 2020;10(1):23- 32.
  11. Parmar ND, Shukla SR. Decolourization of dye wastewater by microbial methods-a review. Indian J Chem Technol. 2019;25(4):315-23.
  12. Saini RD. Textile organic dyes: polluting effects and elimination methods from textile waste water. Int J Chem Eng Res. 2017;9(1):121-36.
  13. Singh K, Kumar P, Srivastava R. An overview of textile dyes and their removal techniques: Indian perspective. Pollut Res. 2017;36(4):790-7.
  14. Farraji H, Zaman NQ, Tajuddin R, Faraji H. Advantages and disadvantages of phytoremediation: a concise review. Int J Environ Sci Technol. 2016;2:69-75.
  15. Gowri RS, Vijayaraghavan R, Meenambigai P. Microbial degradation of reactive dyes-a review. Int J Curr Microbiol Appl Sci. 2014;3:421-36.
  16. Leelakriangsak M, Borisut S. Characterization of the decolorizing activity of azo dyes by Bacillus subtilis azoreductase AzoR1. Songklanakarin J Sci Technol. 2012;34(5):509-16.

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Related

Metadata

Authors
Emadi, Z., Sadeghi, M., & Forouzandeh, S.
Affiliations
  • Student Research Committee, Shahrekord University of Medical Sciences, Shahrekord, Iran
  • Shahrekord University of Medical Sciences (IR)
  • Department of Environmental Health Engineering, School of Health, Shahrekord University of Medical Sciences, Shahrekord, Iran
Corresponding author
Sadeghi, Mehraban
ORCID
Venue
Avicenna Journal of Environmental Health Engineering
Publisher
Maad Rayan Publishing Company
Published
2025-12-30
Volume
12
Issue
2
Pages
128-145
ISSN
2423-4583 (ISSN-L)
DOI
10.34172/ajehe.5491
OpenAlex
W7131402796
Cited by
4
References
130
Citations by year
2026: 4
FWCI
1.67
Type
journal article
Language
en
Open access
Licence
cc-by
Locations
  • Avicenna Journal of Environmental Health Engineering (publishedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
Topics
  • Life Sciences › Immunology and Microbiology › Applied Microbiology and Biotechnology › Enzyme-mediated dye degradation
  • Physical Sciences › Environmental Science › Water Science and Technology › Adsorption and biosorption for pollutant removal
  • Physical Sciences › Environmental Science › Pollution › Microbial bioremediation and biosurfactants
Keywords
azo dyes, textile wastewater, biological decolorization, bacterial decolorization, dye degradation, dye adsorption, flocculation, operating conditions

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