Fenton coupled with nanofiltration for elimination of Bisphenol A

Bisphenol A (BPA) is a typical Endocrine Disrupting Chemical (EDC), which is potentially harmful during wastewater reclamation. In this study, its degradation during Fenton's process under different operational conditions was investigated in combination with subsequent nanofiltration of low concentration remnant BPA and compounds derived from oxidation. The results indicate that BPA could be degraded efficiently in aqueous phase by Fenton, even at very low hydrogen peroxide doses. The treatment of up to 300 mg/L solutions of BPA with Fenton liquor at optimal conditions resulted in its complete removal in less than 2 min. The optimal conditions were found to be pH, = 3, H2O2/BPA = 020 and Fe2+/BPA = 0.012. Five NF polymeric membranes having different properties were used for the nanofiltration of treated and non-treated solutions. The nanofiltration of BPA solutions showed that rejection is related to adsorption ability of BPA on the membrane and size exclusion mechanism. In the nanofiltration of the effluent after Fenton oxidation, high TOC, COD, colour and Fe2+ (>77%) removal were achieved, although significant membrane fouling was also observed. The normalised water flux after membrane flushing with water was lower than 60% in almost all used membranes, which indicates significant non-easily removable fouling. (C) 2014 Elsevier B.V. All rights reserved.Peer ReviewedPostprint (author’s final draft

Fenton coupled with nanofiltration for elimination of Bisphenol A

Bisphenol A (BPA) is a typical Endocrine Disrupting Chemical (EDC), which is potentially harmful during wastewater reclamation. In this study, its degradation during Fenton's process under different operational conditions was investigated in combination with subsequent nanofiltration of low concentration remnant BPA and compounds derived from oxidation. The results indicate that BPA could be degraded efficiently in aqueous phase by Fenton, even at very low hydrogen peroxide doses. The treatment of up to 300 mg/L solutions of BPA with Fenton liquor at optimal conditions resulted in its complete removal in less than 2 min. The optimal conditions were found to be pH, = 3, H2O2/BPA = 020 and Fe2+/BPA = 0.012. Five NF polymeric membranes having different properties were used for the nanofiltration of treated and non-treated solutions. The nanofiltration of BPA solutions showed that rejection is related to adsorption ability of BPA on the membrane and size exclusion mechanism. In the nanofiltration of the effluent after Fenton oxidation, high TOC, COD, colour and Fe2+ (>77%) removal were achieved, although significant membrane fouling was also observed. The normalised water flux after membrane flushing with water was lower than 60% in almost all used membranes, which indicates significant non-easily removable fouling. (C) 2014 Elsevier B.V. All rights reserved.Peer Reviewe

Performance of sludge based catalysts in catalytic wet oxidation of phenol

The catalytic potential of sludge based materials produced by steam or CO2 activation from non treated dewatered raw sludge or dewatered mesophilic anaerobically digested sludge were tested in the oxidation of phenol. Batch and continuous experiments were conducted to assess activity and stability of carbons in terms of phenol conversion, carbon burn off and metal leaching. Overall, catalytic activity of materials can be considered very satisfactory when compared to commercial carbons. However, further research on preparation is required to improve their thermal and mechanical stability and resistance to metal leaching.Peer ReviewedPostprint (published version

Extraction and purification of hydrolytic enzymes from activated sludge

A major proportion of the organic matter contained by domestic wastewater is mainly formed by lipids, proteins and carbohydrates. In order to degrade this organic matter, microorganisms produce hydrolytic enzymes like proteases, lipases and other enzymes that cannot be produced by standard cultivation techniques, which makes its recovery of interest. In the present study protease and lipase were extracted by using magnetic stirring and ultrasound disintegration combined with different additives. It was observed that the concentration of Triton X100 has a great influence in the extraction of protease, but it has no effect in the extraction of lipase. Samples obtained after ultrasound disintegration with 0% and 2% Triton X100 were further purified by precipitation with ammonium sulphate and dialysis. These samples were frozen and lyophilized in order to recover them in powder form. The optimal process for the recovery of lipase was a combination of ultrasound treatment using 0% TX100, followed by dialysis and lyophilization. This process allowed recovering around 23 lipase units/g solid.Peer ReviewedPostprint (published version

Performance comparison of torus and magnetically-stirred reactor for the enzymatic elimination of phenol

The goal of this work is the comparison of the performances of a torus and a stirred reactor for the enzymatic elimination of phenol. High degrees of conversion were obtained in both reactors for the three initial concentrations of phenol tested. In the case of the torus reactor, around 97%, 85% and 56% of phenol conversion were obtained for initial phenol concentrations of 0.5, 1.1 mM and 1.6 mM respectively, with the optimal concentrations of hydrogen peroxide. In the case of using the magnetically-stirred vessel, the extension of the phenol elimination was around 89%, 67% and 58% for an initial phenol concentration of 0.5 mM, 1.1 mM and 1.6 mM respectively. No significative differences were observed for both reactors, nevertheless the phenol conversion that was always higher for the torus reactor. Also, the values of the initial reaction rates were always lower in the stirred reactor, suggesting that the mixing in the torus reactor is more effective. The optimal H2O2 initial concentration to achieve the highest conversion of phenol has to be a ratio equal to 1 between the phenol and the H2O2 initial molar concentration. The excess of hydrogen peroxide in the mixture inhibited the activity of the enzyme, by the conversion of the peroxidase to inactive forms, provoking a reduction of the phenol conversion

Fenton coupled with nanoflitration for elimination of tartrazine

Peer ReviewedPostprint (published version

Trickle bed reactor for the oxidation of phenol over active carbon catalyst

The catalytic wet air oxidation of phenol using activated carbon has been performed in a laboratory trickle bed reactor over a wide range of operating variables (PO2, T, FL and Cph,o) and hydrodynamic conditions. The influence of different start-up procedures (saturation of activated carbon) has also been tested. Further improvement of activity and stability has been checked for by using dynamic TBR operation concept or impregnated Fe/carbon catalyst. The results obtained confirm that the combination of Trickle Bed Reactor and active carbon can lead to an intensified treatment of phenolic waste water.Peer Reviewe

Trickle bed reactor for the oxidation of phenol over active carbon catalyst

The catalytic wet air oxidation of phenol using activated carbon has been performed in a laboratory trickle bed reactor over a wide range of operating variables (PO2, T, FL and Cph,o) and hydrodynamic conditions. The influence of different start-up procedures (saturation of activated carbon) has also been tested. Further improvement of activity and stability has been checked for by using dynamic TBR operation concept or impregnated Fe/carbon catalyst. The results obtained confirm that the combination of Trickle Bed Reactor and active carbon can lead to an intensified treatment of phenolic waste water.Peer ReviewedPostprint (published version

Performance comparison of torus and magnetically-stirred reactor for the enzymatic elimination of phenol

The goal of this work is the comparison of the performances of a torus and a stirred reactor for the enzymatic elimination of phenol. High degrees of conversion were obtained in both reactors for the three initial concentrations of phenol tested. In the case of the torus reactor, around 97%, 85% and 56% of phenol conversion were obtained for initial phenol concentrations of 0.5, 1.1 mM and 1.6 mM respectively, with the optimal concentrations of hydrogen peroxide. In the case of using the magnetically-stirred vessel, the extension of the phenol elimination was around 89%, 67% and 58% for an initial phenol concentration of 0.5 mM, 1.1 mM and 1.6 mM respectively. No significative differences were observed for both reactors, nevertheless the phenol conversion that was always higher for the torus reactor. Also, the values of the initial reaction rates were always lower in the stirred reactor, suggesting that the mixing in the torus reactor is more effective. The optimal H2O2 initial concentration to achieve the highest conversion of phenol has to be a ratio equal to 1 between the phenol and the H2O2 initial molar concentration. The excess of hydrogen peroxide in the mixture inhibited the activity of the enzyme, by the conversion of the peroxidase to inactive forms, provoking a reduction of the phenol conversion.Postprint (published version

Performance comparison of torus and magnetically-stirred reactor for the enzymatic elimination of phenol

The goal of this work is the comparison of the performances of a torus and a stirred reactor for the enzymatic elimination of phenol. High degrees of conversion were obtained in both reactors for the three initial concentrations of phenol tested. In the case of the torus reactor, around 97%, 85% and 56% of phenol conversion were obtained for initial phenol concentrations of 0.5, 1.1 mM and 1.6 mM respectively, with the optimal concentrations of hydrogen peroxide. In the case of using the magnetically-stirred vessel, the extension of the phenol elimination was around 89%, 67% and 58% for an initial phenol concentration of 0.5 mM, 1.1 mM and 1.6 mM respectively. No significative differences were observed for both reactors, nevertheless the phenol conversion that was always higher for the torus reactor. Also, the values of the initial reaction rates were always lower in the stirred reactor, suggesting that the mixing in the torus reactor is more effective. The optimal H2O2 initial concentration to achieve the highest conversion of phenol has to be a ratio equal to 1 between the phenol and the H2O2 initial molar concentration. The excess of hydrogen peroxide in the mixture inhibited the activity of the enzyme, by the conversion of the peroxidase to inactive forms, provoking a reduction of the phenol conversion