Photochemical and Photobiological Sciences, Dec 1, 2015
In this study, the photoreactivation and the modification of dark repair of E. coli in a simulate... more In this study, the photoreactivation and the modification of dark repair of E. coli in a simulated secondary effluent were investigated after initial irradiation in different conditions. The simulated solar exposure of the secondary wastewater was followed by exposure to six different low-intensity fluorescent lamps (blacklight blue, actinic blacklight, blue, green, yellow and indoor light) up to 8 h. When phoreactivation was monitored, blue and green color fluorescent light led to an increased bacterial regrowth. Blacklight lamps further inactivated the remaining bacteria, while yellow and indoor light led to an accelerated growth of healthy cells. Exposure to fluorescent lamps was followed by long term dark storage, to monitor the bacterial repair in the dark. The response was correlated with the pre-exposure dose of applied solar irradiation and at a lesser extent with the fluorescent light dose. Bacteria which have undergone extensive exposure had no response neither under fluorescent light nor during dark storage. Finally, the statistical treatment of the data allowed to suggest a linear model, non-selective in terms of the fluorescent light applied. The estimation of the final bacterial population was well predicted (R-sq~75%) and the photoreactivation risk was found more important cultivable cells.
Batch solar water disinfection (SODIS) is a known, simple and low-cost water treatment technology... more Batch solar water disinfection (SODIS) is a known, simple and low-cost water treatment technology. SODIS is based on the synergistic action of temperature increase and light-assisted generation of Reactive Oxygen Species (ROS) on bacteria. ROS are generated via the action of solar photons on i) Natural Organic Matter (NOM), ii) some mineral components of water (Fe oxides or Fe-organic complexes, nitrogen compounds ) and iii) endogenous bacteria photosensitizers (e.g. cytochrome). SODIS has proven its effectiveness for remote settlements or urban slums in regions with high incident solar radiation. All of the internal and external simultaneous processes are often driven by photoactive Fe-species present in the cell, as well as in the natural water sources. In SODIS, a temperature of 50 °C is required and due to this temperature dependence, only 1-2 L can be treated at a time. As required exposure time strongly depends on irradiation intensity and temperature, some SODIS households could be overburdened, leading to inadequate treatment and probable bacterial re-growth. This is why TiO 2 photocatalysis and Fe photo-assisted systems (i.e. photo-Fenton reactants) have been considered to enhance the photo-catalytic processes already present in natural water sources when exposed to solar light. Both TiO 2 and Fe-photoassisted processes, when applied to water disinfection aim to improve the performance of solar bacteria inactivation systems by i) enhancing ROS production, ii) making the process independent from the rise in temperature and as a consequence iii) allowing the treatment of larger volumes than 1-2 L of water and iv) prevent bacterial (re)growth, sometimes observed after sole solar treatment.
Environmental Science and Pollution Research, Jul 1, 2015
The photo-disinfection of natural alkaline surface water (pH 8.6±0.3) for drinking purposes was c... more The photo-disinfection of natural alkaline surface water (pH 8.6±0.3) for drinking purposes was carried out under solar radiation treatments. The enteric bacteria studied were the wild total coliforms/Escherichia coli (10 4 CFU/ml) and Salmonella spp. (10 4 CFU/ml) naturally present in the water. The photo-disinfection of a 25-l water sample was carried out in a solar compound parabolic collector (CPC) in the absence and in the presence of hydrogen peroxide (H 2 O 2 ). The addition of H 2 O 2 (10 mg/L) to the sample water was sufficient to enhance the photo-disinfection and ensure an irreversible lethal action on the wild enteric bacteria contents of the sample. The inactivation kinetic of the system was significantly enhanced compared to the one carried out without H 2 O 2 addition. The effect of the solar radiation parameters on the efficiency of the photo-disinfection were assessed. The pH has increased during the treatment in all the photodisinfection processes (hv and H 2 O 2 /hv). The Salmonella spp strain has shown the best effective inactivate time in alkaline water than the one recorded under acidic or near-neutral conditions. The evolution of some physico-chemical parameters of the water (turbidity, NO 2 -, NO 3 -, NH 4 + , HPO 4 2-, and bicarbonate (HCO 3 - )) was monitored during the treatment. Finally, the possible mechanistic process involved during the enteric bacteria inactivation was suggested.
Note: Poster Abstract: ECOR-1 - Oxidation and Reduction for Technologies for Ex-Situ and In-Situ ... more Note: Poster Abstract: ECOR-1 - Oxidation and Reduction for Technologies for Ex-Situ and In-Situ Treatment of Water, Air and Soil, Sartorius College, Gottingen, Germany (April 25-28,2004) Reference LBE-POSTER-2004-005 Record created on 2005-03-02, modified on 2016-08-08
Note: Poster abstract: 2nd European Meeting on Solar-Chemistry and Photocatalysis: Environmental ... more Note: Poster abstract: 2nd European Meeting on Solar-Chemistry and Photocatalysis: Environmental Application, Saint-Avold (FR), May 29-31, 2002 Reference LBE-POSTER-2002-018 Record created on 2005-03-02, modified on 2016-08-08
Degradación Foto-Fenton de Precursores de DBPS, en Aguas Naturales Utilizadas en la Obtención de ... more Degradación Foto-Fenton de Precursores de DBPS, en Aguas Naturales Utilizadas en la Obtención de Agua Potable, Empleando un Reactor Solar CPC
An efficient, visible light active, N, S-codoped TiO 2-based photocatalyst was prepared by reacti... more An efficient, visible light active, N, S-codoped TiO 2-based photocatalyst was prepared by reacting thiourea with nanoparticulate anatase TiO 2. Commercial anatase powders were manually ground with thiourea and annealed at 400°C in two crucibles with different surface-to-volume ratios (S/V) 20 and 1.5) to prepare two N, S-codoped TiO 2 materials. The differentiated aeration conditions during the catalyst annealing on the crucibles allowed for different amounts of O 2 to reach the catalyst surface. The first material, with S/V) 20, herein referred to as D-TKP 102-A, was clear beige colored. The second material, with S/V) 1.5, herein referred to as D-TKP 102-B, was darker and revealed a markedly lower efficiency in Escherichia coli inactivation. The D-TKP 102-A powder presented visible light absorption due to the nitrogen (N) and sulfur (S) doping. X-ray photoelectron spectroscopy signals for this catalyst were observed for N 1s peaks at binding energies of 399.2 and 400.7 eV due to interstitial N-doping or Ti-ON species. The S 2p were due to SO 4-2 signals with BE >168 eV and signals at 162.8 and 167.2 eV due to anionic and cationic S-doping, respectively. By fast kinetic spectroscopy, the decay of the electron induced by pulsed light at λ) 450 nm (∼8 ns/laser pulse) was followed for the D-TKP 102-A catalyst. Undoped D-TKP 102 catalyst did not promote the electron in the visible range, and consequently no signal decay could be observed in the latter case. Low-temperature electron spin resonance measurements at 8 K provided evidence for electrons trapped in shallow traps, such as oxygen vacancies, V o , induced by N, S doped on D-TKP 102-A. The ESR measurements implementing the reactive scavenging with singlet oxygen scavenger, TMP-OH, revealed the production of singlet oxygen (1 O 2).
The Canadian Journal of Chemical Engineering, 1981
The electrochemical oxidation of phenol for waste water treatment applications was investigated o... more The electrochemical oxidation of phenol for waste water treatment applications was investigated on lead dioxide packed‐bed anodes. Cells were operated in both batch and continuous modes with feed streams up to 1100 nig/1 phenol dissolved in aqueous solutions of Na2SO4 and H2SO4 or NaOH. All the phenol in solution could be readily oxidized but complete total organic carbon (T.O.C.) removal was more difficult. The percent phenol oxidized increased with increasing current density, and decreased as initial phenol concentration, electrolyte flow rate, pH and anode particle size were increased. Results are compared to simple mathematical models.
This review addresses the preparation of antibacterial 2D textile and thin polymer films and 3D s... more This review addresses the preparation of antibacterial 2D textile and thin polymer films and 3D surfaces like catheters for applications in hospital and health care facilities. The sputtering of films applying different levels of energy led to the deposition of metal/oxide/composite/films showing differentiated antibacterial kinetics and surface microstructure. The optimization of the film composition in regards to the antibacterial active component was carried out in each case to attain the fastest antibacterial kinetics, since this is essential when designing films avoiding biofilm formation (under light and in the dark). The antimicrobial performance of these sputtered films on Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) were tested. A protecting effect of TiO₂ was found for the release of Cu by the TiO₂-Cu films compared to films sputtered by Cu only. The Cu-released during bacterial inactivation by TiO₂-Cu was observed to be much lower compared to the films sput...
Note: Abstracts: The Third International Conference on TiO2 Photocatalytic Purification and Treat... more Note: Abstracts: The Third International Conference on TiO2 Photocatalytic Purification and Treatment of Water and Air, Orlando, Florida, USA, September 23-26, 1997 Reference LBE-POSTER-1997-002 Record created on 2005-03-02, modified on 2016-08-08
Visible light plays a significant role during bacterial inactivation by the photo-fenton process,... more Visible light plays a significant role during bacterial inactivation by the photo-fenton process, even at sub-critical light intensities,
The present work presents a kinetic analysis of the exogenous photo-induced disinfection of E. co... more The present work presents a kinetic analysis of the exogenous photo-induced disinfection of E. coli in natural waters. Herein, the inactivation of bacteria by light and photo-generated transient species, i.e., hydroxyl radical (HO •), excited triplet states of organic matter (3 CDOM*) and singlet oxygen (1 O 2), was studied. It was found that the exogenous disinfection of E. coli proceeds through a lag time, followed by an exponential phase triggered by photo-generated HO • , 1 O 2 and 3 CDOM*. Also, we report that the concentration increase of transient species (and especially HO •) precursors decreased the lag times of bacteria inactivation. Due to the limitations of the competition kinetics methodology to include the lag phase, an alternative strategy to study the interaction between E. coli and photo-generated transient species was proposed, considering the log-linear pseudo-first order rate constants and lag-times. On this basis and by using APEX software, a full kinetic analysis of exogenous bacterial inactivation, taking into account both lag-time and exponential decay, was developed. This approach provided insights into the conditions that could make exogenous inactivation competitive with the endogenous process for the E. coli inactivation in natural sunlit waters. Hence, this research contributes to the understanding of fundamental kinetic aspects of photoinduced bacterial inactivation, which is the basis for light-assisted processes such as the solar disinfection (SODIS).
Solar photo-Fenton disinfection of 11 antibiotic-resistant bacteria (ARB) and elimination of repr... more Solar photo-Fenton disinfection of 11 antibiotic-resistant bacteria (ARB) and elimination of representative AR genes. Evidence that antibiotic resistance does not imply resistance to oxidative treatment
T oxidative conditions. Finally, in the view of application in drinking water treatment, the proc... more T oxidative conditions. Finally, in the view of application in drinking water treatment, the process performed well in the lightly acidic region, due to the physicochemical implications of natural waters' pH in iron cycling.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. E. coli-MS2 bacteriophage interactions during solar disinfection of wastewater and the subsequent post-irradiation period.
Photochemical and Photobiological Sciences, Dec 1, 2015
In this study, the photoreactivation and the modification of dark repair of E. coli in a simulate... more In this study, the photoreactivation and the modification of dark repair of E. coli in a simulated secondary effluent were investigated after initial irradiation in different conditions. The simulated solar exposure of the secondary wastewater was followed by exposure to six different low-intensity fluorescent lamps (blacklight blue, actinic blacklight, blue, green, yellow and indoor light) up to 8 h. When phoreactivation was monitored, blue and green color fluorescent light led to an increased bacterial regrowth. Blacklight lamps further inactivated the remaining bacteria, while yellow and indoor light led to an accelerated growth of healthy cells. Exposure to fluorescent lamps was followed by long term dark storage, to monitor the bacterial repair in the dark. The response was correlated with the pre-exposure dose of applied solar irradiation and at a lesser extent with the fluorescent light dose. Bacteria which have undergone extensive exposure had no response neither under fluorescent light nor during dark storage. Finally, the statistical treatment of the data allowed to suggest a linear model, non-selective in terms of the fluorescent light applied. The estimation of the final bacterial population was well predicted (R-sq~75%) and the photoreactivation risk was found more important cultivable cells.
Batch solar water disinfection (SODIS) is a known, simple and low-cost water treatment technology... more Batch solar water disinfection (SODIS) is a known, simple and low-cost water treatment technology. SODIS is based on the synergistic action of temperature increase and light-assisted generation of Reactive Oxygen Species (ROS) on bacteria. ROS are generated via the action of solar photons on i) Natural Organic Matter (NOM), ii) some mineral components of water (Fe oxides or Fe-organic complexes, nitrogen compounds ) and iii) endogenous bacteria photosensitizers (e.g. cytochrome). SODIS has proven its effectiveness for remote settlements or urban slums in regions with high incident solar radiation. All of the internal and external simultaneous processes are often driven by photoactive Fe-species present in the cell, as well as in the natural water sources. In SODIS, a temperature of 50 °C is required and due to this temperature dependence, only 1-2 L can be treated at a time. As required exposure time strongly depends on irradiation intensity and temperature, some SODIS households could be overburdened, leading to inadequate treatment and probable bacterial re-growth. This is why TiO 2 photocatalysis and Fe photo-assisted systems (i.e. photo-Fenton reactants) have been considered to enhance the photo-catalytic processes already present in natural water sources when exposed to solar light. Both TiO 2 and Fe-photoassisted processes, when applied to water disinfection aim to improve the performance of solar bacteria inactivation systems by i) enhancing ROS production, ii) making the process independent from the rise in temperature and as a consequence iii) allowing the treatment of larger volumes than 1-2 L of water and iv) prevent bacterial (re)growth, sometimes observed after sole solar treatment.
Environmental Science and Pollution Research, Jul 1, 2015
The photo-disinfection of natural alkaline surface water (pH 8.6±0.3) for drinking purposes was c... more The photo-disinfection of natural alkaline surface water (pH 8.6±0.3) for drinking purposes was carried out under solar radiation treatments. The enteric bacteria studied were the wild total coliforms/Escherichia coli (10 4 CFU/ml) and Salmonella spp. (10 4 CFU/ml) naturally present in the water. The photo-disinfection of a 25-l water sample was carried out in a solar compound parabolic collector (CPC) in the absence and in the presence of hydrogen peroxide (H 2 O 2 ). The addition of H 2 O 2 (10 mg/L) to the sample water was sufficient to enhance the photo-disinfection and ensure an irreversible lethal action on the wild enteric bacteria contents of the sample. The inactivation kinetic of the system was significantly enhanced compared to the one carried out without H 2 O 2 addition. The effect of the solar radiation parameters on the efficiency of the photo-disinfection were assessed. The pH has increased during the treatment in all the photodisinfection processes (hv and H 2 O 2 /hv). The Salmonella spp strain has shown the best effective inactivate time in alkaline water than the one recorded under acidic or near-neutral conditions. The evolution of some physico-chemical parameters of the water (turbidity, NO 2 -, NO 3 -, NH 4 + , HPO 4 2-, and bicarbonate (HCO 3 - )) was monitored during the treatment. Finally, the possible mechanistic process involved during the enteric bacteria inactivation was suggested.
Note: Poster Abstract: ECOR-1 - Oxidation and Reduction for Technologies for Ex-Situ and In-Situ ... more Note: Poster Abstract: ECOR-1 - Oxidation and Reduction for Technologies for Ex-Situ and In-Situ Treatment of Water, Air and Soil, Sartorius College, Gottingen, Germany (April 25-28,2004) Reference LBE-POSTER-2004-005 Record created on 2005-03-02, modified on 2016-08-08
Note: Poster abstract: 2nd European Meeting on Solar-Chemistry and Photocatalysis: Environmental ... more Note: Poster abstract: 2nd European Meeting on Solar-Chemistry and Photocatalysis: Environmental Application, Saint-Avold (FR), May 29-31, 2002 Reference LBE-POSTER-2002-018 Record created on 2005-03-02, modified on 2016-08-08
Degradación Foto-Fenton de Precursores de DBPS, en Aguas Naturales Utilizadas en la Obtención de ... more Degradación Foto-Fenton de Precursores de DBPS, en Aguas Naturales Utilizadas en la Obtención de Agua Potable, Empleando un Reactor Solar CPC
An efficient, visible light active, N, S-codoped TiO 2-based photocatalyst was prepared by reacti... more An efficient, visible light active, N, S-codoped TiO 2-based photocatalyst was prepared by reacting thiourea with nanoparticulate anatase TiO 2. Commercial anatase powders were manually ground with thiourea and annealed at 400°C in two crucibles with different surface-to-volume ratios (S/V) 20 and 1.5) to prepare two N, S-codoped TiO 2 materials. The differentiated aeration conditions during the catalyst annealing on the crucibles allowed for different amounts of O 2 to reach the catalyst surface. The first material, with S/V) 20, herein referred to as D-TKP 102-A, was clear beige colored. The second material, with S/V) 1.5, herein referred to as D-TKP 102-B, was darker and revealed a markedly lower efficiency in Escherichia coli inactivation. The D-TKP 102-A powder presented visible light absorption due to the nitrogen (N) and sulfur (S) doping. X-ray photoelectron spectroscopy signals for this catalyst were observed for N 1s peaks at binding energies of 399.2 and 400.7 eV due to interstitial N-doping or Ti-ON species. The S 2p were due to SO 4-2 signals with BE >168 eV and signals at 162.8 and 167.2 eV due to anionic and cationic S-doping, respectively. By fast kinetic spectroscopy, the decay of the electron induced by pulsed light at λ) 450 nm (∼8 ns/laser pulse) was followed for the D-TKP 102-A catalyst. Undoped D-TKP 102 catalyst did not promote the electron in the visible range, and consequently no signal decay could be observed in the latter case. Low-temperature electron spin resonance measurements at 8 K provided evidence for electrons trapped in shallow traps, such as oxygen vacancies, V o , induced by N, S doped on D-TKP 102-A. The ESR measurements implementing the reactive scavenging with singlet oxygen scavenger, TMP-OH, revealed the production of singlet oxygen (1 O 2).
The Canadian Journal of Chemical Engineering, 1981
The electrochemical oxidation of phenol for waste water treatment applications was investigated o... more The electrochemical oxidation of phenol for waste water treatment applications was investigated on lead dioxide packed‐bed anodes. Cells were operated in both batch and continuous modes with feed streams up to 1100 nig/1 phenol dissolved in aqueous solutions of Na2SO4 and H2SO4 or NaOH. All the phenol in solution could be readily oxidized but complete total organic carbon (T.O.C.) removal was more difficult. The percent phenol oxidized increased with increasing current density, and decreased as initial phenol concentration, electrolyte flow rate, pH and anode particle size were increased. Results are compared to simple mathematical models.
This review addresses the preparation of antibacterial 2D textile and thin polymer films and 3D s... more This review addresses the preparation of antibacterial 2D textile and thin polymer films and 3D surfaces like catheters for applications in hospital and health care facilities. The sputtering of films applying different levels of energy led to the deposition of metal/oxide/composite/films showing differentiated antibacterial kinetics and surface microstructure. The optimization of the film composition in regards to the antibacterial active component was carried out in each case to attain the fastest antibacterial kinetics, since this is essential when designing films avoiding biofilm formation (under light and in the dark). The antimicrobial performance of these sputtered films on Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) were tested. A protecting effect of TiO₂ was found for the release of Cu by the TiO₂-Cu films compared to films sputtered by Cu only. The Cu-released during bacterial inactivation by TiO₂-Cu was observed to be much lower compared to the films sput...
Note: Abstracts: The Third International Conference on TiO2 Photocatalytic Purification and Treat... more Note: Abstracts: The Third International Conference on TiO2 Photocatalytic Purification and Treatment of Water and Air, Orlando, Florida, USA, September 23-26, 1997 Reference LBE-POSTER-1997-002 Record created on 2005-03-02, modified on 2016-08-08
Visible light plays a significant role during bacterial inactivation by the photo-fenton process,... more Visible light plays a significant role during bacterial inactivation by the photo-fenton process, even at sub-critical light intensities,
The present work presents a kinetic analysis of the exogenous photo-induced disinfection of E. co... more The present work presents a kinetic analysis of the exogenous photo-induced disinfection of E. coli in natural waters. Herein, the inactivation of bacteria by light and photo-generated transient species, i.e., hydroxyl radical (HO •), excited triplet states of organic matter (3 CDOM*) and singlet oxygen (1 O 2), was studied. It was found that the exogenous disinfection of E. coli proceeds through a lag time, followed by an exponential phase triggered by photo-generated HO • , 1 O 2 and 3 CDOM*. Also, we report that the concentration increase of transient species (and especially HO •) precursors decreased the lag times of bacteria inactivation. Due to the limitations of the competition kinetics methodology to include the lag phase, an alternative strategy to study the interaction between E. coli and photo-generated transient species was proposed, considering the log-linear pseudo-first order rate constants and lag-times. On this basis and by using APEX software, a full kinetic analysis of exogenous bacterial inactivation, taking into account both lag-time and exponential decay, was developed. This approach provided insights into the conditions that could make exogenous inactivation competitive with the endogenous process for the E. coli inactivation in natural sunlit waters. Hence, this research contributes to the understanding of fundamental kinetic aspects of photoinduced bacterial inactivation, which is the basis for light-assisted processes such as the solar disinfection (SODIS).
Solar photo-Fenton disinfection of 11 antibiotic-resistant bacteria (ARB) and elimination of repr... more Solar photo-Fenton disinfection of 11 antibiotic-resistant bacteria (ARB) and elimination of representative AR genes. Evidence that antibiotic resistance does not imply resistance to oxidative treatment
T oxidative conditions. Finally, in the view of application in drinking water treatment, the proc... more T oxidative conditions. Finally, in the view of application in drinking water treatment, the process performed well in the lightly acidic region, due to the physicochemical implications of natural waters' pH in iron cycling.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. E. coli-MS2 bacteriophage interactions during solar disinfection of wastewater and the subsequent post-irradiation period.
Drastic bacterial enhancement was observed when the Ag(3%)-TiO2 nanotubes were modified with FeOx... more Drastic bacterial enhancement was observed when the Ag(3%)-TiO2 nanotubes were modified with FeOx (3%) magnetic oxide. On bare TiO2- nanotubes a reduction of 0.2log10CFU was observed within one hour under simulated low intensity solar light. Under similar conditions, a bacterial reduction of 2.5log10CFU was observed on Ag(3%)TiO2 increasing to 6.0log10CFU on Ag(3%)-TiO2-FeOx(3%) magnetic nanotubes. The bacterial inactivation kinetics is strongly influenced by the addition of FeOx. The fast inactivation induced by the composite catalyst seems to involve an increase in the interfacial charge transfer (IFCT) compared to a 2-oxide composite photocatalyst. Stable recycling of the photocatalyst was observed leading to bacterial oxidation. The unambiguous identification of the radical intermediates: OH-radicals, O-singlet and the valence holes vb(h + ) on the Ag-TiO2-FeOx interface showed that the valence band holes vb(h + ) were the main oxidative intermediates leading to bacterial inactivation. Nanotubes size, crystallinity and bulk composition of magnetite 1% (θ = 51.0°), anatase 5% (θ = 8.9°), goethite 37.3% (θ = 9.0°), silver 1% (θ = 2.7°) was obtained by the Rietveld refinement for the Ag(3%)-TiO2-FeOx(3%) nanotubes. The redox chemistry during bacterial inactivation was determined by X-ray photoelectron spectroscopy (XPS).
In this work, the use of Advanced Oxidation Processes (AOPs) against the degradation of an emergi... more In this work, the use of Advanced Oxidation Processes (AOPs) against the degradation of an emerging contaminant has been subjected under systematic investigation. The optimization of treatment of the anti-depressant drug Venlafaxine (VFA) was performed, using UV light, the combined UV/H2O2 process, solar light, Fenton and finally the solar photo-Fenton process in laboratory scale. The degradation kinetics, the time necessary to remove 90% of the contaminant and the optimal reactants concentration were proposed. The treatment in pure water, (synthetic) wastewater and urine was assessed, in an effort to identify the opportunities and pitfalls the application of process would encounter in a field application. Treatment by the UV-based methods was found sufficiently efficient and the application of the solar photo-Fenton process showed feasibility in a potential field application with appropriate context. Real urban wastewater effluents after biological and physicochemical treatment were tested, as well as human urine, as a proposal for on-site collection and treatment was also treated. Biological treatment before applying the tested AOPs improved their efficiency, and the strategy of diluting urine prior to treatment greatly enhanced the efficacy of the process. Finally, the identification of the degradation pathway and the biodegradability tests of AOPs treated VFA solutions exhibit promising results concerning the strategy of treatment for similar pollutants of emerging concern.
In this work, disinfection by 5 Advanced Oxidation Processes was preceded by 3 different secondar... more In this work, disinfection by 5 Advanced Oxidation Processes was preceded by 3 different secondary treatment systems present in the wastewater treatment plant of Vidy, Lausanne (Switzerland). 5 AOPs after two biological treatment methods (conventional activated sludge and moving bed bioreactor) and a physiochemical process (coagulation-flocculation) were tested in laboratory scale. The dependence among AOPs efficiency and secondary (pre)treatment was estimated by following the bacterial concentration i) before secondary treatment, ii) after the different secondary treatment methods and iii) after the various AOPs. Disinfection and post-treatment bacterial regrowth were the evaluation indicators. The order of efficiency was Moving Bed Bioreactor > Activated Sludge > Coagulation-Flocculation > Primary Treatment. As far as the different AOPs are concerned, the disinfection kinetics were: UVC/H 2 O 2 > UVC and solar photo-Fenton > Fenton or solar light. The contextualization and parallel study of microorganisms with the micropollutants of the effluents revealed that higher exposure times were necessary for complete degradation compared to microorganisms for the UV-based processes and inversed for the Fenton-related ones. Nevertheless, in the Fenton-related systems, the nominal 80% removal of micropollutants deriving from the Swiss legislation, often took place before the elimination of bacterial regrowth risk.
Solar disinfection is an augmentable, in situ-generated photo-Fenton reaction—Part 2: A review of the applications for drinking water and wastewater disinfection, Dec 5, 2016
This is the second part of a comprehensive review article about photo-Fenton reaction at near-neu... more This is the second part of a comprehensive review article about photo-Fenton reaction at near-neutral pH used for water and wastewater disinfection. In this part, a critical revision of the fundamental physical , chemical and biological parameters affecting the photo-catalytic process efficiency are discussed. The effects of the chemical aspects, considered either as facilitators or competitors of photo-Fenton are deeply analyzed, with special focus on organic matter and its effect over bacterial inactivation. The role of sol-ubilized iron and the biological nature of different pathogens are deeply assessed according to reported experimental data. Water temperature, turbidity, and radiation parameters like solar UV energy, ligh scattering and absorption during photo-Fenton are pictured in terms of treatment efficiency and suitable reactor design. Recent unconventional photo-Fenton strategies using iron chelates, iron oxides (including zero valent iron) and iron-based materials are also highlighted as new approaches to this process. Finally, the existing pilot scale studies in real conditions using photo-Fenton at near-neutral pH are revised, while alternative options and further research for real implementation are proposed.
Solar disinfection is an augmentable, in situ-generated photo-Fenton reaction—Part 1: A review of the mechanisms and the fundamental aspects of the process, Dec 15, 2016
The present manuscript is a conceptual review concerning the photo-Fenton reaction at near-neutra... more The present manuscript is a conceptual review concerning the photo-Fenton reaction at near-neutral pH, used for bacterial inactivation. In this first Part, an overview of the mechanisms involved, as well as the fundamental concepts governing the near-neutral photo-Fenton reaction are critically assessed. The two constituents of the process, namely solar light and the Fenton reagents, are dissociated, with their direct and indirect actions thoroughly analyzed. The effects of UVB and UVA on the bacterial cell are firstly discussed, followed by the presentation of the indirect oxidative stress-related inactivation mechanisms initiated into the microorganism, in presence of light. Afterwards, the effect of each Fenton reagent (H2O2, Fe) is analyzed in a step-wise manner, with H2O2 and Fe as enhancements of the solar disinfection mode of action. This approach proves that in fact, the solar photo-Fenton reaction is an enhanced solar disinfection process. Finally, the photo-Fenton reaction is put into context by considering the possible interactions of the separate parts of the combined process with the constituents of the natural environment that can play an important role in the evolution of the bacterial inactivation.
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