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Ioannou L.A.,International Water Research Center | Ioannou L.A.,University of Cyprus | Fatta-Kassinos D.,International Water Research Center | Fatta-Kassinos D.,University of Cyprus
Journal of Environmental Chemical Engineering | Year: 2013

This work examined the solar-photo Fenton oxidation against the bioresistant fractions of winery wastewater. Winery effluents already treated by a membrane bioreactor (MBR) were subjected to further purification by solar photo-Fenton oxidation process (hv/Fe2+/H2O2). The effect of various operating variables, such as the catalyst and oxidant concentration, as well as temperature and solar irradiation on the abatement of chemical oxygen demand (COD), dissolved organic carbon (DOC), color, toxicity and phytotoxicity has been assessed. Optimum Fe2+ and H 2O2 concentrations were found to be 3 mg L-1 and 250 mg L-1, respectively. Solar photo-Fenton has been demonstrated to be an effective process for the purification of winery effluents, yielding after 120 min of treatment, COD, DOC and color removal of 70 ± 3.3%, 53 ± 3.7% and 75 ± 2.2%, respectively. The residual COD and DOC values after the end of the solar treatment were 33 mg L-1 and 14.1 mg L-1, respectively. In the various operating conditions studied, the extent of mineralization (assessed by DOC) was lower than the COD decrease, implying that partial oxidation reactions of the organic content prevailed over total oxidation to CO2 and water. Moreover, the process efficiency was found to increase with temperature up to a point (∼70% at 25 C), and then reach a plateau with a small increase by further increasing the temperature to 45 C. Finally, the toxic and the phytotoxic compounds still present in the effluent after the biological treatment were reduced or even eliminated through solar photo-Fenton oxidation. © 2013 Elsevier Ltd. All rights reserved.


Frontistis Z.,Technical University of Crete | Drosou C.,Technical University of Crete | Tyrovola K.,Technical University of Crete | Mantzavinos D.,Technical University of Crete | And 5 more authors.
Industrial and Engineering Chemistry Research | Year: 2012

The efficiency of TiO2 photocatalysis to degrade three estrogen hormones, that is, 17α-ethynylestradiol (EE2), estrone (E1), and 17β-estradiol (E2), in environmentally relevant samples was investigated. Radiation at a photon flux of 1.7 × 10-7 einstein/s was provided by a solar simulator and experiments were conducted at various TiO 2 loadings (25-1500 mg/L), estrogen concentrations (85-300 μg/L in individual solutions and 400 μg/L in mixture), and water matrices (ultrapure water, drinking water, and secondary treated wastewater). Changes in estrogen concentration were followed by high performance liquid chromatography and estrogenicity by the yeast estrogen screening assay. Aeroxide P25, a commercially available mixture of 75:25 anatase/rutile, was considerably more active than carbon-doped and undoped anatase titania, with degradation increasing with increasing catalyst loading and treatment time. The organic and inorganic constituents typically found in wastewater and drinking water impeded degradation presumably due to the scavenging of oxidizing species. For example, the time needed for complete 100 μg/L EE2 degradation in pure water was an order of magnitude lower than that in wastewater. The three estrogens exhibited comparable reactivity, with E1 being slightly more reactive than the rest. Degradation in multicomponent mixtures was slower than in individual solutions, thus implying estrogen competition for oxidizing species. Although the mixture of three in wastewater could be degraded fully after 120 min, overall estrogenicity was reduced by just about 30%, highlighting the role of the complex water matrix. Several oxidation products of EE2 were identified by means of LC-MS/MS and a reaction network for the photocatalytic degradation of EE2 is suggested. An artificial neural network comprising five input variables (reaction time, TiO2 and EE2 concentration, organic content, and conductivity of the water matrix), eight neurons and an output variable (conversion) was optimized, tested, and validated for EE2 degradation. The network, based on tangent sigmoid and linear transfer functions for the hidden and input/output layers, respectively, and the Levenberg-Marquardt back-propagation training algorithm, can successfully predict EE2 degradation. © 2012 American Chemical Society.


Ioannou L.A.,International Water Research Center | Ioannou L.A.,University of Cyprus | Michael C.,International Water Research Center | Michael C.,University of Cyprus | And 6 more authors.
Separation and Purification Technology | Year: 2013

Membrane processes have received in recent years considerable attention for the separation and concentration of inorganic and organic compounds from various wastewater streams. This work investigated the efficiency of a pilot-scale reverse osmosis (RO) process on the treatment of winery wastewater with an initial chemical oxygen demand (COD) of 5350 mg L-1. The removal of COD by the RO process reached 97% resulting in a permeate with residual COD level lower than 150 mg L-1. Furthermore, the total nitrogen removal reached 67%, total phosphorous 76.2%, total suspended solids 94%, total solids 96%, and conductivity 94%. These results demonstrated an excellent solid and soluble salts separation. Toxicity and phytotoxicity assays in the feed, concentrate and permeate samples were also performed, showing that the toxicity of the original effluent could be reduced or even eliminated through the RO process. Moreover, the volume recovery achieved in the recirculation mode was 65%, whereas in the single pass was 50%. Further treatment of the concentrate (COD 10290 mg L-1) by solar photo-Fenton oxidation achieved a COD reduction of 75%. In an effort to evaluate the capacity of the RO process to concentrate valuable polyphenols, five selected compounds were examined. The process proved to be quite efficient in almost completely concentrating them in the concentrate stream. © 2013 Elsevier B.V. All rights reserved.


Ioannou L.,International Water Research Center | Ioannou L.,University of Cyprus | Michael C.,International Water Research Center | Michael C.,University of Cyprus | And 3 more authors.
Journal of Chemical Technology and Biotechnology | Year: 2014

BACKGROUND: Depending on the nature of the pollutants and the level of contaminants, detoxification of various industrial effluents, as well as winery wastewater, might be difficult and/or even impossible to achieve by single conventional biological methods. In such cases, biological processes alone are not able to reach effluent standards for discharge into the environment, and therefore, a pretreatment or post-treatment is required. In this study, winery effluent already treated in a membrane bioreactor (MBR) was subjected to further treatment by a solar Fenton oxidation process, at pilot and industrial scale. RESULTS: The optimum Fe2+ and H2O2 concentration was found to be 3 mg L-1 and 350 mg L-1, respectively. Solar Fenton oxidation has been demonstrated to be an effective process both at pilot and industrial scale, yielding after 180 min of photocatalytic treatment removals of COD, DOC and color of about 85%, 62-68%, and ∼80%, respectively. CONCLUSIONS: The combined MBR+solar Fenton process seems to be an effective technology for winery wastewater treatment, that can reduce the organic pollutants in the winery effluent to values below that of the Cypriot discharge limits. Moreover, solar Fenton treatment was proved capable of eliminating the toxicity to D. magna, and significantly reducing the phytotoxicity at values well below the starting values induced by the raw effluent. © 2013 Society of Chemical Industry.

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