Carmen Rodrigues - Academia.edu (original) (raw)

Papers by Carmen Rodrigues

Research paper thumbnail of Coupling of acrylic dyeing wastewater treatment by heterogeneous Fenton oxidation in a continuous stirred tank reactor with biological degradation in a sequential batch reactor

Journal of environmental management, Jan 23, 2015

This work deals with the treatment of a recalcitrant effluent, from the dyeing stage of acrylic f... more This work deals with the treatment of a recalcitrant effluent, from the dyeing stage of acrylic fibres, by combination of the heterogeneous Fenton's process in a continuous stirred tank reactor (CSTR) with biological degradation in a sequential batch reactor (SBR). Three different catalysts (a commercial Fe/ZSM-5 zeolite and two distinct Fe-containing activated carbons - ACs - prepared by wet impregnation of iron acetate and iron nitrate) were employed on the Fenton's process, and afterwards a parametric study was carried out to determine the effect of the main operating conditions, namely the hydrogen peroxide feed concentration, temperature and contact time. Under the best operating conditions found, using the activated carbon impregnated with iron nitrate, 62.7% of discolouration and 39.9% of total organic carbon (TOC) reduction were achieved, at steady-state. Furthermore, a considerable increase in the effluent's biodegradability was attained (BOD5:COD ratio increase...

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Research paper thumbnail of Heterogeneous Fenton’s oxidation using Fe/ZSM-5 as catalyst in a continuous stirred tank reactor

Separation and Purification Technology, 2015

ABSTRACT

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Research paper thumbnail of A new strategy for treating a cotton dyeing wastewater - integration of physical-chemical and advanced oxidation processes

Int. J. of Environment and Waste Management, Vol.14, No.3, pp.232 - 255, 2014

ABSTRACT

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Research paper thumbnail of Synthetic textile dyeing wastewater treatment by integration of advanced oxidation and biological processes - Performance analysis with costs reduction

ABSTRACT Color and organic matter removals from acrylic, cotton and polyester dyeing wastewaters ... more ABSTRACT Color and organic matter removals from acrylic, cotton and polyester dyeing wastewaters were evaluated by biological oxidation in a Sequential Batch Reactor (SBR) and by integration of Fenton’s reaction with SBR. Raw and chemically oxidized pre-treated wastewaters were fed to the biological reactor during 10 cycles (i.e., up to pseudo-steady state conditions). Because the biological degradation did not allow obtaining effluents complying with the discharge limits, neither did the chemical oxidation per se, coupling the SBR after chemical oxidation was required. In the integrated chemical-biological process a new strategy was applied in the optimization of Fenton’s oxidation, consisting in the application of the optimum doses of Fe(II) and H2O2 (for biodegradability enhancement and maximization of color and DOC removals), but with the simultaneous objective of minimizing the operating costs. The integration of Fenton’s oxidation with a downstream SBR provides much better removals of organic matter (88–98% for COD, 83–95% for BOD5 and 91–98% for DOC, values depending on the particular textile effluent being used) and color (> 99%) than the biological or chemical treatment alone. Besides, such integrated treatment allows treated wastewaters to meet the discharge limits with a reduction of the operating costs, in the range 24–39% comparatively to Fenton’s oxidation alone.

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Research paper thumbnail of Application of Fenton's Reagent for Acrylic Dyeing Wastewater Decolorization, Organic Matter Reduction and Biodegradability Improvement

Journal of Advanced …, 2012

Page 1. 78 J. Adv. Oxid. Technol. Vol. 15, No. 1, 2012 ISSN 1203-8407 © 2012 Science & Techno... more Page 1. 78 J. Adv. Oxid. Technol. Vol. 15, No. 1, 2012 ISSN 1203-8407 © 2012 Science & Technology Network, Inc. Application of Fenton´s Reagent for Acrylic Dyeing Wastewater Decolorization, Organic Matter Reduction and Biodegradability Improvement ...

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Research paper thumbnail of Optimization of the azo dye Procion Red H-EXL degradation by Fenton's reagent using experimental design

Journal of Hazardous Materials, 2009

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Research paper thumbnail of Treatment of textile effluent by chemical (Fenton's Reagent) and biological (sequencing batch reactor) oxidation

Journal of Hazardous Materials, 2009

The removal of organic compounds and colour from a synthetic effluent simulating a cotton dyeing ... more The removal of organic compounds and colour from a synthetic effluent simulating a cotton dyeing wastewater was evaluated by using a combined process of Fenton's Reagent oxidation and biological degradation in a sequencing batch reactor (SBR). The experimental design methodology was first applied to the chemical oxidation process in order to determine the values of temperature, ferrous ion concentration and hydrogen peroxide concentration that maximize dissolved organic carbon (DOC) and colour removals and increase the effluent's biodegradability. Additional studies on the biological oxidation (SBR) of the raw and previously submitted to Fenton's oxidation effluent had been performed during 15 cycles (i.e., up to steady-state conditions), each one with the duration of 11.5h; Fenton's oxidation was performed either in conditions that maximize the colour removal or the increase in the biodegradability. The obtained results allowed concluding that the combination of the two treatment processes provides much better removals of DOC, BOD(5) and colour than the biological or chemical treatment alone. Moreover, the removal of organic matter in the integrated process is particularly effective when Fenton's pre-oxidation is carried out under conditions that promote the maximum increase in wastewater biodegradability.

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Research paper thumbnail of Decontamination of an Industrial Cotton Dyeing Wastewater by Chemical and Biological Processes

Industrial & Engineering Chemistry Research, 2014

ABSTRACT

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Research paper thumbnail of Treatment of textile dye wastewaters using ferrous sulphate in a chemical coagulation/flocculation process

Environmental Technology, 2013

The coagulation/flocculation treatment using FeSO4 x 7H2O as a coagulant is evaluated in this wor... more The coagulation/flocculation treatment using FeSO4 x 7H2O as a coagulant is evaluated in this work for the removal of organic compounds and colour from synthetic effluents simulating the cotton, acrylic and polyester dyeing wastewaters. The coagulant dose, temperature, pH, stirring speed and stirring time that maximized the removal of dissolved organic carbon (DOC) and colour for each effluent are determined for the coagulation process. The effect of the stirring speed, stirring time and the dose of flocculant (Magnafloc 155 or Superfloc C-573) on the flocculation stage is also evaluated for effluents pretreated by coagulation at the optimal conditions previously determined. The obtained results showed that the optimal operating conditions are different for each effluent, and the process (coagulation/flocculation) as a whole was efficient in terms of colour removal (-91% for cotton, -94% for acrylic effluents; polyester effluent is practically colourless). However, the DOC removal observed is not significant (33% for polyester, -45% for cotton and -28% for acrylic effluents). On the other hand, the remaining dissolved iron content is appropriate for further integrating the treatment with an iron-catalysed Fenton process, thus reducing the consumption of chemicals in the overall treatment.

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Research paper thumbnail of Technical and economic feasibility of polyester dyeing wastewater treatment by coagulation/flocculation and Fenton's oxidation

Environmental Technology, 2014

This study aims to investigate the efficiency of individual and integrated processes applied to o... more This study aims to investigate the efficiency of individual and integrated processes applied to organic matter abatement and biodegradability improvement of a polyester dyeing wastewater, namely coagulation/flocculation combined with Fenton's reagent (Approach 1), Fenton oxidation alone (Approach 2) and its integration with coagulation/flocculation (Approach 3). The effects of Fe2+ dose, initial concentration of the oxidant (H202) and temperature during Fenton's oxidation were evaluated in Approaches 1 and 2, whereas in Approach 3 the influence ofpH and flocculant dose was also assessed, during the coagulation/flocculation stage. Toxicity and biodegradability of the final effluent were also evaluated. After oxidation, a slight increase in the specific oxygen uptake rate of the effluent was observed (from 27.0 up to 28.5-30.0mg O2/(gVSSh)) and the inhibition to Vibrio fischeri was eliminated. An effluent that complies with discharge standards was obtained in all cases; however, Approach 3 revealed to be a promising solution for treating this effluent as it leads to smaller operating costs. Therefore, the use of dissolved iron resulting from Fenton's oxidation as coagulant in the second stage was shown to be an innovative, efficient and economically attractive strategy for treating these effluents.

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Research paper thumbnail of Experimental design to optimize the degradation of the synthetic dye Orange II using Fenton's reagent

Catalysis Today, 2005

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Research paper thumbnail of Optimization and economic analysis of textile wastewater treatment by photo-fenton process under artificial and simulated solar radiation

ABSTRACT

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Research paper thumbnail of Experimental Design to Optimize Degradation of Organic Compounds in Wastewater from Semiconductor Industry Using Fenton Reagent

The aim of this work was to study the possibility of treating an industrial semiconductor wastewa... more The aim of this work was to study the possibility of treating an industrial semiconductor wastewater by combining physical and chemical methods. The combined treatment consisted of pH adjustment to 2 followed by filtration and then chemical oxidation with Fenton reagent over the resulting filtered wastewater. In chemical oxidation treatment, the isolated effect of the variables on the degradation of the organic compounds-measured by chemical oxygen demand (COD) removal-was first studied: pH (3 to 5), reaction time (0.25 to 5 hours), hydrogen peroxide concentration (2.1 to 5.9 M) and FeSO 4 : H 2 O 2 mass ratio (1:5 to 3:2). Higher COD removal (75%) was obtained when a pH value of 3, reaction time of 4 hours, hydrogen peroxide concentration of 4.2 M and FeSO 4 : H 2 O 2 mass ratio of 1:5 were used. The global efficiency of COD removal by combination of the two treatments was 80%. The influence of three variables and their interactions was evaluated, using an experimental design of the type 2 3. The design also allowed the conclusion that reaction time has a statistical meaning.

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Research paper thumbnail of Coupling of acrylic dyeing wastewater treatment by heterogeneous Fenton oxidation in a continuous stirred tank reactor with biological degradation in a sequential batch reactor

Journal of environmental management, Jan 23, 2015

This work deals with the treatment of a recalcitrant effluent, from the dyeing stage of acrylic f... more This work deals with the treatment of a recalcitrant effluent, from the dyeing stage of acrylic fibres, by combination of the heterogeneous Fenton's process in a continuous stirred tank reactor (CSTR) with biological degradation in a sequential batch reactor (SBR). Three different catalysts (a commercial Fe/ZSM-5 zeolite and two distinct Fe-containing activated carbons - ACs - prepared by wet impregnation of iron acetate and iron nitrate) were employed on the Fenton's process, and afterwards a parametric study was carried out to determine the effect of the main operating conditions, namely the hydrogen peroxide feed concentration, temperature and contact time. Under the best operating conditions found, using the activated carbon impregnated with iron nitrate, 62.7% of discolouration and 39.9% of total organic carbon (TOC) reduction were achieved, at steady-state. Furthermore, a considerable increase in the effluent's biodegradability was attained (BOD5:COD ratio increase...

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Research paper thumbnail of Heterogeneous Fenton’s oxidation using Fe/ZSM-5 as catalyst in a continuous stirred tank reactor

Separation and Purification Technology, 2015

ABSTRACT

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Research paper thumbnail of A new strategy for treating a cotton dyeing wastewater - integration of physical-chemical and advanced oxidation processes

Int. J. of Environment and Waste Management, Vol.14, No.3, pp.232 - 255, 2014

ABSTRACT

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Research paper thumbnail of Synthetic textile dyeing wastewater treatment by integration of advanced oxidation and biological processes - Performance analysis with costs reduction

ABSTRACT Color and organic matter removals from acrylic, cotton and polyester dyeing wastewaters ... more ABSTRACT Color and organic matter removals from acrylic, cotton and polyester dyeing wastewaters were evaluated by biological oxidation in a Sequential Batch Reactor (SBR) and by integration of Fenton’s reaction with SBR. Raw and chemically oxidized pre-treated wastewaters were fed to the biological reactor during 10 cycles (i.e., up to pseudo-steady state conditions). Because the biological degradation did not allow obtaining effluents complying with the discharge limits, neither did the chemical oxidation per se, coupling the SBR after chemical oxidation was required. In the integrated chemical-biological process a new strategy was applied in the optimization of Fenton’s oxidation, consisting in the application of the optimum doses of Fe(II) and H2O2 (for biodegradability enhancement and maximization of color and DOC removals), but with the simultaneous objective of minimizing the operating costs. The integration of Fenton’s oxidation with a downstream SBR provides much better removals of organic matter (88–98% for COD, 83–95% for BOD5 and 91–98% for DOC, values depending on the particular textile effluent being used) and color (> 99%) than the biological or chemical treatment alone. Besides, such integrated treatment allows treated wastewaters to meet the discharge limits with a reduction of the operating costs, in the range 24–39% comparatively to Fenton’s oxidation alone.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Application of Fenton's Reagent for Acrylic Dyeing Wastewater Decolorization, Organic Matter Reduction and Biodegradability Improvement

Journal of Advanced …, 2012

Page 1. 78 J. Adv. Oxid. Technol. Vol. 15, No. 1, 2012 ISSN 1203-8407 © 2012 Science & Techno... more Page 1. 78 J. Adv. Oxid. Technol. Vol. 15, No. 1, 2012 ISSN 1203-8407 © 2012 Science & Technology Network, Inc. Application of Fenton´s Reagent for Acrylic Dyeing Wastewater Decolorization, Organic Matter Reduction and Biodegradability Improvement ...

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Research paper thumbnail of Optimization of the azo dye Procion Red H-EXL degradation by Fenton's reagent using experimental design

Journal of Hazardous Materials, 2009

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Treatment of textile effluent by chemical (Fenton's Reagent) and biological (sequencing batch reactor) oxidation

Journal of Hazardous Materials, 2009

The removal of organic compounds and colour from a synthetic effluent simulating a cotton dyeing ... more The removal of organic compounds and colour from a synthetic effluent simulating a cotton dyeing wastewater was evaluated by using a combined process of Fenton's Reagent oxidation and biological degradation in a sequencing batch reactor (SBR). The experimental design methodology was first applied to the chemical oxidation process in order to determine the values of temperature, ferrous ion concentration and hydrogen peroxide concentration that maximize dissolved organic carbon (DOC) and colour removals and increase the effluent's biodegradability. Additional studies on the biological oxidation (SBR) of the raw and previously submitted to Fenton's oxidation effluent had been performed during 15 cycles (i.e., up to steady-state conditions), each one with the duration of 11.5h; Fenton's oxidation was performed either in conditions that maximize the colour removal or the increase in the biodegradability. The obtained results allowed concluding that the combination of the two treatment processes provides much better removals of DOC, BOD(5) and colour than the biological or chemical treatment alone. Moreover, the removal of organic matter in the integrated process is particularly effective when Fenton's pre-oxidation is carried out under conditions that promote the maximum increase in wastewater biodegradability.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Decontamination of an Industrial Cotton Dyeing Wastewater by Chemical and Biological Processes

Industrial & Engineering Chemistry Research, 2014

ABSTRACT

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Research paper thumbnail of Treatment of textile dye wastewaters using ferrous sulphate in a chemical coagulation/flocculation process

Environmental Technology, 2013

The coagulation/flocculation treatment using FeSO4 x 7H2O as a coagulant is evaluated in this wor... more The coagulation/flocculation treatment using FeSO4 x 7H2O as a coagulant is evaluated in this work for the removal of organic compounds and colour from synthetic effluents simulating the cotton, acrylic and polyester dyeing wastewaters. The coagulant dose, temperature, pH, stirring speed and stirring time that maximized the removal of dissolved organic carbon (DOC) and colour for each effluent are determined for the coagulation process. The effect of the stirring speed, stirring time and the dose of flocculant (Magnafloc 155 or Superfloc C-573) on the flocculation stage is also evaluated for effluents pretreated by coagulation at the optimal conditions previously determined. The obtained results showed that the optimal operating conditions are different for each effluent, and the process (coagulation/flocculation) as a whole was efficient in terms of colour removal (-91% for cotton, -94% for acrylic effluents; polyester effluent is practically colourless). However, the DOC removal observed is not significant (33% for polyester, -45% for cotton and -28% for acrylic effluents). On the other hand, the remaining dissolved iron content is appropriate for further integrating the treatment with an iron-catalysed Fenton process, thus reducing the consumption of chemicals in the overall treatment.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Technical and economic feasibility of polyester dyeing wastewater treatment by coagulation/flocculation and Fenton's oxidation

Environmental Technology, 2014

This study aims to investigate the efficiency of individual and integrated processes applied to o... more This study aims to investigate the efficiency of individual and integrated processes applied to organic matter abatement and biodegradability improvement of a polyester dyeing wastewater, namely coagulation/flocculation combined with Fenton's reagent (Approach 1), Fenton oxidation alone (Approach 2) and its integration with coagulation/flocculation (Approach 3). The effects of Fe2+ dose, initial concentration of the oxidant (H202) and temperature during Fenton's oxidation were evaluated in Approaches 1 and 2, whereas in Approach 3 the influence ofpH and flocculant dose was also assessed, during the coagulation/flocculation stage. Toxicity and biodegradability of the final effluent were also evaluated. After oxidation, a slight increase in the specific oxygen uptake rate of the effluent was observed (from 27.0 up to 28.5-30.0mg O2/(gVSSh)) and the inhibition to Vibrio fischeri was eliminated. An effluent that complies with discharge standards was obtained in all cases; however, Approach 3 revealed to be a promising solution for treating this effluent as it leads to smaller operating costs. Therefore, the use of dissolved iron resulting from Fenton's oxidation as coagulant in the second stage was shown to be an innovative, efficient and economically attractive strategy for treating these effluents.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Experimental design to optimize the degradation of the synthetic dye Orange II using Fenton's reagent

Catalysis Today, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Optimization and economic analysis of textile wastewater treatment by photo-fenton process under artificial and simulated solar radiation

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Experimental Design to Optimize Degradation of Organic Compounds in Wastewater from Semiconductor Industry Using Fenton Reagent

The aim of this work was to study the possibility of treating an industrial semiconductor wastewa... more The aim of this work was to study the possibility of treating an industrial semiconductor wastewater by combining physical and chemical methods. The combined treatment consisted of pH adjustment to 2 followed by filtration and then chemical oxidation with Fenton reagent over the resulting filtered wastewater. In chemical oxidation treatment, the isolated effect of the variables on the degradation of the organic compounds-measured by chemical oxygen demand (COD) removal-was first studied: pH (3 to 5), reaction time (0.25 to 5 hours), hydrogen peroxide concentration (2.1 to 5.9 M) and FeSO 4 : H 2 O 2 mass ratio (1:5 to 3:2). Higher COD removal (75%) was obtained when a pH value of 3, reaction time of 4 hours, hydrogen peroxide concentration of 4.2 M and FeSO 4 : H 2 O 2 mass ratio of 1:5 were used. The global efficiency of COD removal by combination of the two treatments was 80%. The influence of three variables and their interactions was evaluated, using an experimental design of the type 2 3. The design also allowed the conclusion that reaction time has a statistical meaning.

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