Cr(VI) reduction by activated carbon and non-living macrophytes roots as assessed by Kβ spectroscopy

In this work, the behavior of cationic-exchange resin, activated carbon, and non-living aquatic macrophytes biomasses on the Cr(VI) and Cr(III) uptake and Cr(VI) reduction was investigated. The high-resolution X-ray fluorescence (HR-XRF) technique was used to study the adsorption process, as well as to study Cr(VI) reduction and removal from metal solutions. Batch Cr ions sorption experiments at pH 3.5 were carried out in order to speciate 3d-transition metal onto the surface of these types of adsorbents by a Kβ spectra analysis. Cr-Kβ satellite lines have been characterized for all Kβ spectra of Cr ions onto treated samples and reference material. Based on their energy position and intensity of Cr-Kβ satellite lines as well as their related to reference material shift energy, activated carbon and non-living aquatic macrophytes roots were found to act mainly as good adsorbents, first reducing Cr(VI) to Cr(III) and then followed by a Cr(III) adsorption. Although cationic-exchange resin was treated with Cr(VI) solution, no evidence of any Cr-Kβ spectral satellite lines was shown in it, suggesting that Cr(VI) was not removed in a cationic-exchange process. Evidence of reduction of hexavalent chromium by adsorbent materials was assessed by Kβ spectral lines analysis.Fil: Módenes, Aparecido N.. Universidade Estadual Do Oeste Do Pará; BrasilFil: Espinoza Quiñones, Fernando R.. Universidade Estadual Do Oeste Do Pará; BrasilFil: Palácio, Soraya M.. Universidade Estadual Do Oeste Do Pará; BrasilFil: Kroumov, Alexander D.. University of Kentucky; Estados UnidosFil: Stutz, Guillermo Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Tirao, German Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Camera, Adriana S.. Universidade Estadual Do Oeste Do Pará; Brasi

Modeling Biodegradation Kinetics on Benzene and Toluene and Their Mixture

The objective of this work was to model the biodegradation kinetics of toxic compounds toluene and benzene as pure substrates and in a mixture. As a control, Monod and Andrews models were used. To predict substrates interactions, more sophisticated models of inhibition and competition, and SKIP (sum kinetics interactions parameters) model were applied. The models evaluation was performed based on the experimental data from Pseudomonas putida F1 activities published in the literature. In parameter identification procedure, the global method of particle swarm optimization (PSO) was applied. The simulation results show that the better description of the biodegradation process of pure toxic substrate can be achieved by Andrews' model. The biodegradation process of a mixture of toxic substrates is modeled the best when modified competitive inhibition and SKIP models are used. The developed software can be used as a toolbox of a kinetics model catalogue of industrial wastewater treatment for process design and optimization

Improvement on the concentrated grape juice physico-chemical characteristics by an enzymatic treatment and Membrane Separation Processes

ABSTRACT In this work, the improvement on the concentrated grape juice physico-chemical characteristics by using an enzymatic treatment followed by Membrane Separation Process (MSP) has been investigated. By using Novozym 33095(r) and Ultrazym AFP L(r) enzymes varying three operating parameters, the best result on the grape pulp characteristics was attained for the Novozym 33095(r) performed at 35oC, 15 min. and 50 mgL-1. In micro/ultra filtration processes after enzymatic pretreatment, the best performance of the MSP with high permeate flux value and suitable grape juice characteristics was attained using 0.05 mm membrane pore size, 1 bar pressure and 40 oC treatment temperature. When reverse osmosis process is operated at 40 bar and 40oC, high soluble solid and low turbidity values are attained. An enzymatic treatment along with MSP has shown an alternative and efficient grape juice processing system, being possible to extend to other foods

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

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

Performance evaluation of different solar advanced oxidation processes applied to the treatment of a real textile dyeing wastewater

The performance of different solar-driven advanced oxidation processes (AOPs), such as TiO2/UV, TiO2/H2O2/UV, and Fe2+/H2O2/UV-visible in the treatment of a real textile effluent using a pilot plant with compound parabolic collectors (CPCs), was investigated. The influence of the main photo-Fenton reaction variables such as iron concentration (20-100 mg Fe2+ L-1), pH (2.4-4.5), temperature (10-50 °C), and irradiance (22-68 WUV m-2) was evaluated in a lab-scale prototype using artificial solar radiation. The real textile wastewater presented a beige color, with a maximum absorbance peak at 641 nm, alkaline pH (8.1), moderate organic content (dissolved organic carbon (DOC) = 129 mg C L-1 and chemical oxygen demand (COD) = 496 mg O2 L-1), and high conductivity mainly associated to the high concentration of chloride (1.1 g Cl- L-1), sulfate (0.4 g SO 4 2 - L- 1), and sodium (1.2 g Na+ L-1) ions. Although all the processes tested contributed to complete decolorization and effective mineralization, the most efficient process was the solar photo-Fenton with an optimum catalyst concentration of 60 mg Fe2+ L-1, leading to 70 % mineralization (DOCfinal = 41 mg C L-1; CODfinal < 150 mg O2 L-1) at pH 3.6, requiring a UV energy dose of 3.5 kJUV L-1 (t30 W = 22.4 min; (Formula presented.); (Formula presented.)) and consuming 18.5 mM of H2O2. (c) 2014 Springer-Verlag Berlin Heidelberg