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São João da Madeira, Portugal

Martins R.C.,University of Coimbra | Pinto F.L.,University of Coimbra | Castro-Silva S.,Centro Empresarial e Tecnologico | Quinta-Ferreira R.M.,University of Coimbra
Journal of Environmental Engineering (United States)

This paper reports the application of flocculation, Fenton's process, and ozonation on the depuration of distillery wastewaters. The treatment processes were analyzed separately; nevertheless, integration schemes were also considered. The commercial flocculant 923PWG led to up to 84% of total suspended solids (TSS) removal even if a very low chemical oxygen demand (COD) abatement was observed (<2%). The effect of hydrogen peroxide concentration and [H2O2]/[Fe2+] molar ratio were tested on the Fenton's process efficiency. Moreover, the H2O2 injection mode was still analyzed. Gathering up both COD degradation and biodegradability enhancement, it was possible to select the following operating conditions: [H2O2]=0.5 M and [H2O2]/[Fe2+]=10 (mol/mol), being the oxidant totally introduced at the beginning of the reaction. Ozonation showed poor results regarding organic matter removal; however, it seems to be an interesting methodology raising the effluent's biochemical oxygen demand (BOD5)/COD ratio. In fact, in the strategies involving the integration of ozonation with Fenton's process, it was possible to conclude that ozone oxidation did not improve COD degradation; nonetheless, it was essential to improve biodegradability, particularly when conducting ozonation (at pH=3) after Fenton's process was revealed to be an interesting approach leading to an effluent amenable to further biodegradation. © 2013 American Society of Civil Engineers. Source

Amaral-Silva N.,University of Coimbra | Martins R.C.,University of Coimbra | Castro-Silva S.,Centro Empresarial e Tecnologico | Quinta-Ferreira R.M.,University of Coimbra
Journal of Advanced Oxidation Technologies

Water savings, reclamation and reuse in industry are topics of increasing economic interest due to water scarcity and costs. The search for an efficient and economical method to the depuration of two different effluents, namely from vegetable wash (VW) and chemical production (CP), was investigated by advanced oxidation processes as direct ozonation and O 3/H 2O 2 focusing in the evaluation of their effectiveness for decomposing COD and TOC aiming water reuse. The O 3/H 2O 2 combined system showed the highest oxidizing power amongst the two ozonation methodologies with stronger COD and TOC degradation degrees corresponding to 100% (0 mgO 2.L -1) and 33% (38 mgC.L -1) after 120 min for the VW and 96% (38 mgO 2.L -1) and 66% (62 mgC.L -1) for the CP after 180 minutes of oxidizing procedure. From the global analysis of the results it was possible to conclude that water reutilization is feasible when the perozonation process is applied fulfilling the environmental regulations. © 2012 Science & Technology Network, Inc. Source

Martins R.C.,University of Coimbra | Jimenez B.M.,University of Coimbra | Castro-Silva S.,Centro Empresarial e Tecnologico | Quinta-Ferreira R.M.,University of Coimbra
Ozone: Science and Engineering

This article explores the application of several ozone-based technologies on the abatement of a bio-refractory stream coming from an elderberry juice plant (BOD5/COD = 0.26). The impact of ozone inlet concentration and pH was addressed firstly, followed by the analysis of the O3+H2O2 combined system. Finally, the activity and stability of two solid catalysts (Mn-Ce-O and Fe-Mn-O) was assessed. None of the approaches produced values within the legal thresholds for direct discharge into water-courses. It is advisable to integrate the chemical treatment with a bio-reactor. Thus, single ozonation at pH = 3 (BOD5/COD = 0.48), O3+[H2O2] = 32.5 mM (BOD5/COD = 0.46) and O3+Mn-Ce-O at pH = 3 (BOD5/COD = 0.44) are promising strategies. © 2012 Copyright 2012 International Ozone Association. Source

Martins R.C.,University of Coimbra | Silva A.M.T.,Centro Empresarial e Tecnologico | Castro-Silva S.,Centro Empresarial e Tecnologico | Garcao-Nunes P.,Centro Empresarial e Tecnologico | Quinta-Ferreira R.M.,University of Coimbra
Environmental Technology

In this experimental work the ozone action on the depuration of olive oil mill wastewater is studied for different operational conditions based on an actual industrial treatment plant. It was verified that the application of a Mn-Ce-O catalyst prepared at the laboratory, with a Mn/Ce molar proportion of 70/30, enhances the depuration efficiency and the effluent biodegradability. Ozonation operation at the natural pH of the effluent is recommended. Moreover, the integration of the Fenton process as a pretreatment improves the final chemical oxygen demand removal and enables a totally biodegradable effluent to be obtained, as confirmed by respirometric techniques. © 2010 Taylor & Francis. Source

Amaral-Silva N.,University of Coimbra | Amaral-Silva N.,Centro Empresarial e Tecnologico | Martins R.C.,University of Coimbra | Castro-Silva S.,Centro Empresarial e Tecnologico | Quinta-Ferreira R.M.,University of Coimbra
Journal of Environmental Chemical Engineering

Landfill leachate effluent as the permeate stream from a reverse osmosis treatment is usually resilient to biological processes due to its very low biodegradability. In order to treat and enhance the biodegradable character of these streams, ozonation was evaluated at a lab-scale and different ozone inlet concentrations, initial pH's, and hydrogen peroxide dosages were tested aiming to promote efficiency. The depuration of the landfill leachate by ozone was favored when high pH values were applied or when hydrogen peroxide was used as co-oxidant; both situations were consistent with the major production of hydroxyl radicals. Indeed, the highest organic load removal and biodegradability improvement was observed with the O3/H2O2 process using 4 g H2O2 L-1. This system was able to eliminate 45% of the chemical oxygen demand (COD), 89% of color and also increase the leachate BOD5/COD ratio from 0.05 to 0.29 permitting the treated wastewater discharge for the local sewage collector. Moreover, single ozonation also promoted an expressive removal of the recalcitrant organic matter (43% of COD) and increased leachate biodegradability (BOD5/COD up to 0.22), which makes this process a viable option as a pre-biological treatment. © 2015 Elsevier Ltd. All rights reserved. Source

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