Enhancement of a solar photo-Fenton reaction by using ferrioxalate complexes for the treatment of a synthetic cotton-textile dyeing wastewater

Biological, photo-Fenton (PF) and photo-Fenton mediated by ferrioxalate complexes (PF/Ferrioxalate) processes were examined for the degradation of a synthetic cotton-textile dyeing wastewater. Aerobic biological treatment had a negligible effect on discolouration whereas total organic content decreased mainly due to the biodegradation of acetic acid initially present in the wastewater. PF process yielded a fast and pronounced dissolved organic carbon concentration decay, mostly associated to the abrupt precipitation of Fe(III)-organic complexes. The addition of oxalic acid limited iron precipitation, allowing mineralization of most organic contaminants. The influence of the different dyes and main dyeing auxiliary constituents of the synthetic textile wastewater on the PF and the PF/Ferrioxalate efficiency was systematically analysed. The suitability of combining PF/Ferrioxalate with conventional biological processes as a pre and/or post treatment was evaluated.This study highlights the potential of PF/Ferrioxalate reaction to mineralize the synthetic cotton-textile wastewater under appropriate experimental conditions, the best being: [Fe3+]=40mgL-1, iron/oxalate molar ratio=1:3, pH=4.0 and [H2O2]=50-100 (1.5-2.9)mgL-1 (mmolL-1). At these conditions, the PF/Ferrioxalate treatment was carried out under natural sunlight in a pilot plant equipped with compound parabolic collectors.Fil: Doumic, Lucila Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina. Universidad de Porto; Portugal. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; ArgentinaFil: Soares, Petrick A.. Universidad de Porto; PortugalFil: Ayude, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Cassanello Fernandez, Miryam Celeste. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; ArgentinaFil: Boaventura, Rui A.R.. Universidad de Porto; PortugalFil: Vilar, Vítor J.P.. Universidad de Porto; Portuga

Comparative Analysis of American and Spanish Cruise Passenger's Behavioral Intentions

[EN] Earlier studies of cross-national differences in consumer behavior in different consumption sectors have verified that cultural differences have a strong influence on consumers. Despite the importance of cross-national analysis, no studies in the literature examine the moderating effects of nationality on the construction of behavioral intentions and their antecedents among cruise line passengers. This study investigates the moderating effects of nationality on the relationships between perceived value, satisfaction, trust and behavioral intentions among Spanish and (U.S.) American passengers of cruise lines that use Barcelona as home port and port-of-call. A theoretical model was tested with a total of 968 surveys. Structural equation models (SEMs) were used, by means of a multigroup analysis. Results of this study indicated that Spaniards showed stronger relationships between trust and behavioral intentions, and between emotional value and satisfaction. Americans presented stronger relations.[PT] Estudos em distintos setores de consumo verificaram que as diferenças culturais têm uma forte influência sobre os consumidores. Apesar da importância da análise transnacional, não há estudos na literatura que examinem os efeitos da nacionalidade na construção das intenções de comportamento e seus antecedentes entre os passageiros de cruzeiros. Esta pesquisa investiga os efeitos moderadores da nacionalidade nas relações entre valor percebido, satisfação, confiança e intenções de comportamento entre passageiros espanhóis e norte-americanos. Realizaram-se 968 enquetes para provar o modelo teórico, que foi analisado com modelos de equações estruturais, mediante uma análise multigrupo. Os resultados indicam que os espanhóis mostraram relações mais fortes entre confiança e intenções de comportamento, e entre valor emocional e satisfação. Ao contrário dos norte-americanos, que apresentaram relações mais fortes entre qualidade de serviço e satisfação, e entre qualidade de serviço e intenções de comportamento.[ES] Algunos estudios anteriores de diferencias observadas entre países respecto de las conductas de los consumidores de diferentes sectores de consumo verificaron que las diferencias culturales ejercen una poderosa influencia sobre los consumidores. A pesar de la importancia de los análisis transnacionales, no hay en la literatura estudios que analicen los efectos moderadores de la nacionalidad sobre la construcción de intenciones de conducta y sus antecedentes entre pasajeros de cruceros. Este estudio investiga los efectos moderadores de la nacionalidad sobre las relaciones entre el valor percibido, la satisfacción, la confianza y las intenciones de conducta entre los pasajeros españoles y norteamericanos (EE. UU.) de cruceros, que utilizan a Barcelona como puerto de origen y puerto de escala. Se probó un modelo teórico con un total de 968 encuestas. Se emplearon modelos de ecuaciones estructurales (SEM por su sigla en inglés), a través de un análisis multigrupo. Los resultados de este estudio indicaron que los españoles mostraron relaciones más sólidas entre la confianza y las intenciones de comportamiento y entre el valor emocional y la satisfacción. Los americanos evidenciaron relaciones más sólidas entre la calidad del servicio y la satisfacción y entre la calidad del servicio y las intenciones de conducta.Forgas-Coll, S.; Palau-Saumell, R.; Sanchez-Garcia, J.; Garrigós Simón, FJ. (2016). Comparative Analysis of American and Spanish Cruise Passenger's Behavioral Intentions. RAE-Revista de Administração de Empresas. 56(1):87-100. doi:10.1590/S0034-759020160108S8710056

Enhancement of a solar photo-Fenton reaction with ferric-organic ligands for the treatment of acrylic-textile dyeing wastewater

Literature describes a kinetic mineralization profile for most of acrylic-textile dyeing wastewaters using a photo-Fenton reaction characterized by a slow degradation process and high reactants consumption. This work tries to elucidate that the slow decay on DOC concentration is associated with the formation of stable complexes between Fe3+ and textile auxiliary products, limiting the photoreduction of Fe3+. This work also evaluates the enhancement of a solar photo-Fenton reaction through the use of different ferric-organic ligands applied to the treatment of a simulated acrylic-textile dyeing wastewater, as a pre-oxidation step to enhance its biodegradability. The photo-Fenton reaction was negatively affected by two dyeing auxiliary products: i) Sera (R) Tard A-AS, a surfactant mainly composed of alkyl dimethyl benzyl ammonium chloride and ii) Sera (R) Sperse M-IW, a dispersing agent composed of polyglycol solvents. The catalytic activity of the organic ligands toward the ferrous-catalysed system followed this order: Fe(III)Oxalate > Fe(III)-Citrate > Fe(III)-EDDS, and all were better than the traditional photo-Fenton reaction. Different design parameters such as iron concentration, pH, temperature, flow conditions, UV irradiance and H2O2 addition strategy and dose were evaluated. The ferrioxalate induced photo-Fenton process presented the best results, achieving 87% mineralization after 9.3 kJ(UV) L-1 and allowing to work until near neutral pH values. As expected, the biodegradability of the textile wastewater was significantly enhanced during the photo-Fenton treatment, achieving a value of 73%, consuming 32.4 mM of H2O2 and 5.7 kJ(UV) L-1

Assessment of a multistage system based on electrocoagulation, solar photo-Fenton and biological oxidation processes for real textile wastewater treatment

The performance of a multistage treatment system for textile wastewater was investigated in this study. The processes of electrocoagulation (EC), photo-Fenton oxidation, and activated sludge biological degradation were integrated in batch mode. The integrated treatment system performance was assessed according to three response variables: dissolved organic carbon (DOC), chemical oxygen demand (COD) and biodegradability index. Based on preliminary tests, the EC-based wastewater treatment was suitable as the first stage of the integrated treatment system, followed by the photo-Fenton process. A lab photo-reactor was used to assess the influence of photo-Fenton variables on the process performance. Based on the better lab photo-Fenton reactor conditions, the improvement of some biological indicators related to the organics biodegradability of treated wastewater was investigated in a pilot-scale photoreactor. An activated sludge-based biological reactor at lab-scale was used as a final treatment stage, in order to achieve the legislated limits for discharge into water bodies. Partial degradation of the organic pollutants was achieved by the EC process, with a 36% reduction in COD. In the second treatment stage, a 70% biodegradability index was attained by setting the photo-Fenton reaction conditions at 100 mg Fe2+ L-1, pH 2.8, 12 mM H2O2 and 6.9 kJ L-1 accumulated energy. Finally, a residual COD of 139 mg O-2 L-1 was achieved at the outlet of the biological process, which is below the maximum limit established by the Portuguese legislation

An innovative multistage treatment system for sanitary landfill leachate depuration: Studies at pilot-scale

In this work, an innovative methodology for the treatment of landfill leachates, after aerobic lagooning, is proposed and adjusted at pilot-scale. This methodology involves an aerobic activated sludge biological pre-oxidation (ASBO), a coagulation/sedimentation step (240 mg Fe3+/L, at pH 4.2) and a photo-oxidation through a photo-Fenton (PF) reaction (60 mg Fe2+, at pH 2.8) combining solar and artificial light. The ASBO process applied to a leachate after aerobic lagooning, with high organic and nitrogen content (1.1-1.5 g C/L; 0.8-3.0 g N/L) and low biodegradability (BOD5/COD = 0.07-0.13), is capable to oxidise 62-99% of the ammonium nitrogen, consuming only the affluent alkalinity (70-100%). The coagulation/sedimentation stage led to the humic acids precipitation, promoting a marked change in leachate colour,from dark-brown to yellowish-brown (related to fulvic acids), accompanied by a reduction of 60%, 58% and 88% on DOC, COD and TSS, respectively. The PF system promoted the degradation of the recalcitrant organic molecules into more easily biodegradable ones. According to Zahn-Wellens biodegradability test, a leachate with 419 mg DOC/L after coagulation, would have to be photo-oxidized until DOC 60%. The PF step cost to treat 100 m(3)/day of leachate was 6.41sic/m(3), combining 1339 m(2) of CPCs with lamps

Insights into solar photo-Fenton process using iron(III)-organic ligand complexes applied to real textile wastewater treatment

The treatment of a real textile wastewater was accomplished using a conventional photo-Fenton reaction and mediated by different ferric-organic ligand complexes, performed in lab and pilot scale photoreactors irradiated by simulated and natural solar radiation, respectively. The textile wastewater presents a dark-blue colour, alkaline pH, a high organic content (COD = 1239 mg O-2 L-1; DOC = 408 mg C L-1) and moderate biodegradability (BOD5/COD = 0.16). The conventional solar-photo-Fenton reaction showed limited efficiency in the mineralization of the textile wastewater, which is characterized by a fast initial dissolved organic carbon decay in the absence of light, mainly attributed to the formation of ironorganic pollutants complexes with a low solubility at acidic pH values, leading to iron precipitation, followed by a very slow reaction rate under UV-visible light associated to (i) low amounts of dissolved iron and (ii) low photoactivity of the iron precipitates. The addition of the organic ligands, such as oxalic acid, citric acid and EDDS, enhanced significantly the photo-Fenton reaction, avoiding the formation of ironorganic pollutants complexes, and consequently increase of the quantum yield for ferrous ions production through the photodecarboxylation of ferric-organic ligands complexes. The catalytic activity of the iron-organic ligand complexes increased in the following order: Fe(III)-EDDS < Fe(III)-citrate < Fe(III)-oxalate. All the tested processes mediated by ferric-organic ligands complexes contributed to an effective decolourization and mineralization, but the most efficient system was the photo-Fenton-ferrioxalate reaction with an optimum catalyst concentration of 100 mg Fe3+ L-1, pH 2.8, temperature of 30 degrees C leading to complete decolourization and 69.1% mineralization after less than 8.8 kJuv L-1. An enhancement of the wastewater biodegradability was observed during the photo-Fenton-ferrioxalate reaction

Insights into real cotton-textile dyeing wastewater treatment using solar advanced oxidation processes

Different advanced oxidation processes (AOPs) were applied to the treatment of a real cotton-textile dyeing wastewater as a pre-oxidation step to enhance the biodegradability of the recalcitrant compounds, which can be further oxidized using a biological process. Tests were conducted on a lab-scale prototype using artificial solar radiation and at pilot scale with compound parabolic collectors using natural solar radiation. The cotton-textile dyeing wastewater presents a lilac color, with a maximum absorbance peak at 641 nm, alkaline pH (pH = 8.2), moderate organic content (DOC = 152 mg C L-1, COD = 684 mg O-2 L-1) and low-moderate biodegradability (40 % after 28 days in Zahn-Wellens test). All the tested processes contributed to an effective decolorization and mineralization, but the most efficient process was the solar-photo-Fenton with an optimum catalyst concentration of 60 mg Fe2+ L-1, leading to 98.5 % decolorization and 85.5 % mineralization after less than 0.1 and 5.8 kJ(UV) L-1, respectively. In order to achieve a final wastewater with a COD below 250 mg O-2 L-1 (discharge limit into water bodies imposed by the Portuguese Legislation-Portaria no. 423/97 of 25 June 1997), considering the combination of a solar-photo-Fenton reaction with a biological process, the phototreatment energy required is 0.5 kJ(UV) L-1, consuming 7.5 mM hydrogen peroxide, resulting in 58.4 % of mineralization (t(30W) = 3.2 min; (T) over bar = 30.7 degrees C;(pH) over bar = 2.80; (UV) over bar (G,n) = 13 W m(-2))

Assessment of AOPs as a polishing step in the decolourisation of bio-treated textile wastewater: Technical and economic considerations

Biological oxidation processes have shown good results for the mineralisation of the non-recalcitrant fraction of textile wastewater. However, they do not always represent a feasible technique for colour removal, requiring a polishing step for decolourisation before the wastewater can be discharged into a receiving water body. In this study, UVC/H2O2 and photo-Fenton (PF) oxidation processes were used as a polishing step in the decolourisation of a bio-treated real textile wastewater. The photolysis of hydrogen peroxide using UVC radiation showed decolourisation efficiencies of 86% (Pt-Co method) and 96% (DFZ(436 nm)), consuming 1.6 mM H2O2 after 0.9 KJ(UV) L-1 (time = 35 min; UVC lamp power = 6 W; natural pH 7.8; T = 30 degrees C). The PF reaction was promoted by different radiation sources (UVC, UVA or UVA-vis), showing best results under UVC light. The efficiency of the UVC/Fe2+/H2O2 system was also studied for different iron concentrations, H2O2 availability and pH values. Decolourisation efficiencies of 78% (Pt-Co method) and 93% (DFZ(436 nm)) were achieved applying the UVC/Fe/H2O2 system at pH 2.8 and T = 30 degrees C, consuming 3.6 mM H2O2 after 0.6 KJ(UV) L-1 (time = 25 min; UV lamp power = 6 W). To further investigate the use of solar energy, additional PF assays mediated by ferric-organic ligands under UVA-vis radiation were also performed, considering the effect of the type of ferric-organic ligand as well as the iron/ferric-organic ligand molar ratio, iron concentration and pH. Maximum values for the decolourisation with UVA-vis/Fe3+/H2O2/oxalic acid were 84% (Pt-Co method) and 94% (DFZ(436 nm)), consuming 1.9 mM H2O2 after 2.9 KJ(UV) L-1 (pH 2.8). In addition, the costs associated with the processes studied were estimated. For the optimal conditions, aiming at achieving the legal wastewater discharge requirements, the total unit costs were: (a) 0.25 (sic)m(-3) (UVC/H2O2 at pH 2.8); (b) 0.16 (sic)m(-3) (UVC/H2O2 at natural pH); (c) 0.24 (sic)m(-3) (UVC/Fe2+/H2O2 at pH 2.8); (d) 0.61 (sic)m(-3) (UVA-vis/Fe2+/H2O2 at pH 2.8); (e) 0.79 (sic)m(-3) (UVA-vis/Fe3+/H2O2/oxalic acid at pH 2.8) and; (f) 0.83 (sic)m(-3) (UVA-vis/Fe3+/H2O2/oxalic acid at pH 5.0)

Industrial steel waste as an iron source to promote heterogeneous and homogeneous oxidation/reduction reactions

This work examines the mill scale (MS) of hot rolling, a waste product formed in industrial steel processing. MS was evaluated as an iron source in promoting the oxidation of Reactive Red 120 azo dye in location-sourced and factory textile wastewater through a Fenton reaction (FR), as well as reducing hexavalent chromium species to its trivalent form in the presence of an organic ligand (citric acid). The MS was characterised by various techniques and the results showed that iron is the major compound in its composition and occurs mainly in the form of oxides (wustite, hematite and magnetite). In addition, it has ferromagnetic properties, which facilitate its separation. In the oxidation tests it was observed that acidic pH conditions promoted a positive influence on the reaction efficiency and that the presence of H2O2 can limit the leaching of iron into the solution. The best experimental conditions for colour removal from a RR 120 dye solution containing 35 mg L-1 were 15 g L-1 of MS, 0.5 mM H2O2, pH 3, 25 degrees C, 200 +/- 2 rpm and 120 min. Furthermore, the homogeneous Fenton reaction showed a significant contribution to decolourisation, but the heterogeneous phase cannot be neglected since it is predominant at the beginning of the reactions. In the continuous process, the influence of the H2O2 concentration and the feed rate was evaluated, obtaining an optimal dose of 0.5 mM H2O2 for the RR dye 120 and 0.7 mM H2O2 for the real textile effluent, with a flow rate of 0.25 mL min(-1) and pH 3 for both. Subsequently, the residue was evaluated as the source of iron in the process of reducing Cr(VI) to Cr(III). An increase in the efficiency of the reaction in the presence of citric acid was observed, associated with the removal of the surface oxide layer through the formation of soluble Fe(III)-Cr(III)-ligand complexes and the consequent increase of the iron redox cycle, reducing it to sequencing the reduction of chromium. 100% reduction was obtained in 30 min of reaction using 20 g L-1 of MS, at pH 3 and Cr(VI):citric acid ratio of 1:4. In continuous operation mode, 100% Cr(VI) reduction was obtained during 50 h (1.0 mL min(-1) flow rate), dropping to 20% with increasing flow rate to 4.0 mL min-1 after 200 h of assay

Remediation of a synthetic textile wastewater from polyester-cotton dyeing combining biological and photochemical oxidation processes

This study reports an integrated treatment strategy for synthetic polyester-cotton dyeing wastewater, combining biological and photochemical oxidation processes. The biodegradability of all constituents, dyes and dyeing auxiliary products, present in the synthetic polyester dyeing textile wastewater were firstly analysed through a Zahn-Wellens test. More than 80% of the constituents are easily biodegradable, being possible to achieve its complete removal by biological oxidation. Consequently, the synthetic wastewater was firstly subject to a biological oxidation, achieving a dissolved organic carbon (DOC) removal of 76%, resulting in a bio-treated wastewater with 84 mg L-1 of DOC. The colour reduction was less than 5% Platinum-Cobalt Scale (Pt-Co scale), 9% (DFZ(436nm)), 3% (DFZ(525nm)) and 0% (DFZ(620nm)), (DFZ - DurchsichtFarbZahl, visual colour number in German). Thus, UVC/H2O2 and photo-Fenton (PF) oxidation processes were used as a polishing step for the decolourisation of bio-treated textile wastewater. The PF reaction did not promote wastewater decolourisation as shown by the colour indicators monitored. Moreover, the addition of oxalic acid did not result in an enhancement of the PF reaction. On the other hand, the photolysis of hydrogen peroxide using UVC radiation showed decolourisation efficiencies of 71% (Pt-Co method), 86% (DFZ(436nm)) and 97% (DFZ(525nm)) and more than 40% of mineralisation, consuming 14.1 mM H2O2 and 3.1 kJ(UVC) L-1 of energy dosage (time = 95 min; 6 W UVC lamp; natural pH = 8.4; T = 30 degrees C). The effect of hydrogen peroxide dosage, lamp power, solution pH and temperature on the UVC/H2O2 efficiency for wastewater decolourization was evaluated. During the photochemical reaction some low-molecular-weight carboxylic acids were detected, as oxalic acid, maleic acid and tartaric acid. The integrated treatment strategy was able to achieve a wastewater quality in agreement with the discharge limits imposed by legislation, and the total operating costs was 2.33 (sic) m(-3)