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UV/TiO2 photocatalytic degradation of xanthene dyes

UV/titanium dioxide (TiO2) degradation of two xanthene dyes, erythrosine B (Ery) and eosin Y (Eos), was studied in a photocatalytic reactor. Photocatalysis was able to degrade 98% of Ery and 73% of Eos and led to 65% of chemical oxygen demand removal. Experiments in buffered solutions at different initial pH values reveal the pH dependence of the process, with better results obtained under acidic conditions due...

Surveying activated sludge changes during acclimation with artificial wastewater

Many processes in the chemical and pharmaceutical industries generate wastewater containing organic toxic compounds and other kinds of xenobiotics. Usually, biological treatments are used to degrade a great quantity of these substances. However, most of the time, the microorganisms are not adapted and the treatment can be blocked. Therefore, the first step to make a continuous reactor operative is the acclimati...

Inconvéniants de l’usage d’eau usée synthétique

Photocatalytic and combined anaerobic–photocatalytic treatment of textile dyes

Photocatalytic process based on immobilized titanium dioxide was used to treat crude solutions of azo, anthraquinone and phthalocyanine textile dyes. In addition, the process was applied to the treat autoxidized chemically reduced azo dyes, i.e. representatives of recalcitrant dye residues after biological sequential anaerobic–aerobic treatment. Photocatalysis was able to remove more than 90% color from crude a...

Utilização do processamento digital de imagens no monitoramento de estações de ...

Neste trabalho é proposto um procedimento para reconhecimento semi-automático das espécies de protozoários por análise de imagem. Este programa (ProtoRec v.2) foi em seguida utilizado para estudar a evolução da microfauna durante períodos de transição (paragem e arranque da estação). Os resultados obtidos foram satisfatórios em relação ao reconhecimento das espécies pelo programa e o acompanhamento da estação p...

Using image analysis in the study of multiphase gas absorption

For the air–water–calcium alginate beads system, the effect of the presence of solids on the mass transfer characteristics in a bubble column was experimentally studied. Volumetric liquid side mass transfer coefficient, kLa, specific interfacial area, a, and hence liquid side mass transfer coefficient, kL, were determined under different solid concentrations (0, 5, and 10 vol%), superficial gas velocities (up t...

Effect of solids on gas-liquid mass transfer and bubble characteristics in thre...

Comunicação apresentada no "7th World Congress of Chemical Engineering" em Glasgow, Escócia, em Julho de 2005. ; The effect of the solids on the mass transfer characteristics in a bubble column was studied experimentally for the system air/water/beads of calcium alginate. Volumetric liquid side mass transfer coefficient, kLα, specific interfacial area, α, and liquid side mass transfer coefficient, kL, were det...

Survey of protozoa and metazoa populations in wastewater treatment plants by im...

The biota present in the activated sludge of a wastewater treatment plant are mainly composed of bacteria, Protozoa and Metazoa. The Protozoa and Metazoa species are important micro-organisms taking part in the ecosystem balance in wastewater treatment plants and are quite sensitive to physical, chemical and operational processes. Several authors have established relationships between the predominance of certai...

Development of image analysis techniques as a tool to detect and quantify morph...

Image analysis techniques are applied to monitor the morphological changes in granular sludge present in an expanded granular sludge blanket (EGSB) reactor fed with oleic acid. Deterioration of granular sludge was monitored along the trial period by measuring the percentage of aggregates smaller than 1 mm (in terms of Feret diameter) either in terms of projected area or in terms of number of aggregates. A good ...

Development of image analysis techniques as a tool to detect and quantify morph...

Image analysis techniques were developed and applied to quantify the process of anaerobic granulation in an expanded granular sludge blanket reactor (EGSB) fed with a synthetic substrate based on glucose [60-30% COD chemical oxygen demand)] and volatile fatty acids (40-70% COD) over 376 days. In a first operation period that lasted 177 days, the aggregation of dispersed sludge was quantitatively monitored throu...