Potencial de aplicação do processo foto-fenton/solar como pré-tratamento de efluente da indústria de laticínios

Dairy wastewater is characterized by frequent episodes of drastic increases of organic content, giving rise to bulking filamentous bacteria and compromising the biological treatment process. This study reports the reduction of organic content of such wastewater by the application of the solar photo-Fenton process. For a wastewater containing 335, 2627 or 5400 mg C L-1 between 90% and 50% of the organic carbon content were removed after 3.5 h irradiation. The results show that the solar photo-Fenton process can be a good alternative for the abatement of organic content of dairy wastewater, especially in cases of organic content fluctuation, allowing an efficient biological treatment.

Avaliação da filtração e ozonização de efluente sanitário primário: aspectos de inativação microbiana e variáveis de ozonização

Ozonation tests with and without prior filtration by means of a 50 micron mesh cartridge filter were conducted with primary sanitary effluents. Filtration led to increased inactivation efficiencies with regard to total and thermotolerant coliforms but it did not seem to influence heterotrophic plate count (HPC) bacteria inactivation efficiencies significantly. Application of the Chick-Watson model to experimental data obtained in the situation of constant inactivation showed that the ozone dosage was more important to bacterial inactivation than the contact time with regard to the cases of thermotolerant coliform inactivation in filtered samples and HPC bacteria and total coliform inactivation in non-filtered samples.

Extração líquido-líquido de ferro(III) e titânio(IV) pelo ácido bis-(2-etil-hexil) fosfórico (D2EHPA) em meio de ácido sulfúrico

This work presents a study on the separation of Fe(III) and Ti(IV) from sulfuric acid leaching solutions of ilmenite (FeTiO3) using liquid-liquid extraction with D2EHPA in n-dodecane as extracting agent. The distribution coefficients (K D) of the elements related to free acidity and concentration of Fe(III) and Ti(IV) were determined. Free acidity was changed from 3x10-2 to 11.88 mol L-1 and D2EHPA concentration was fixed at 1.5 mol L-1. Recovery of final products as well as recycling of wastes generated in the process were also investigated. The LLE process as a feasible alternative to obtain high-purity TiO2.

Reutilização de efluente de tingimentos de fibras acrílicas pós-tratamento fotoeletroquímico

On a laboratory scale effluents were produced from bichromic dyeing of acrylic fabrics with the basic dyes Blue Astrazon FGGL 300% and Yellow Gold Astrazon GL 200%. The residual dyeing baths were subjected to a photoelectrochemical treatment and reused in a second dyeing process. In the reutilization study, dyeings with treated effluent were compared with standard dyeings with distilled water. The results of dyeings using 100% of treated effluent were unsatisfactory, but the substitution of 10 to 30% of the treated effluent by distilled water resulted in reduced and more acceptable values for difference in colour intensity (ΔE) between 1.86 and 0.3.

Materiais à base de óxido de ferro para oxidação de compostos presentes no efluente da despolpa do café

Materials based on pure iron oxide and impregnated with niobia (Nb2O5) were prepared. Their catalytic activities were tested on the oxidation of compounds present in the wastewater from the processing of coffee berries. Particularly caffeine and catechol were tested. The oxidation reactions were carried out with the following systems (i) UV/H2O2, (ii) photo-Fenton and (iii) heterogeneous Fenton. All materials were characterized with X-ray diffraction, Mössbauer and infrared spectroscopy. Iron was mainly in the forms of goethite and maghemite. The oxidation kinetics were monitored by UV-vis and the oxidation products were monitored by mass spectrometry. The photo-Fenton reaction presented highest oxidation efficiency, removing 98% of all caffeine and catechol contents.

Extração líquido-líquido de urânio(VI) do colofanito de itataia (Santa Quitéria, Ceará) por extratantes orgânicos em presença de ácido fosfórico

This work describes the liquid-liquid extraction of uranium after digestion of colofanite (a fluoroapatite) from Itataia with sulfuric acid. The experiments were run at room temperature in one stage. Among the solutions tested the highest distribution coefficient (D > 60) was found for 40%vol. DEHPA (di(2-ethyl-hexyl)phosphoric acid) + 20% vol. TOPO (trioctylphosphine oxide) in kerosene. Thorium in the raffinate was quantitatively extracted by TOPO (0.1% vol.) in cyclohexane. Uranium stripping and separation from iron was possible using 1.5 mol L-1 ammonium or sodium carbonate (room temperature, one stage). However, pH control is essential for a good separation.

Degradação fotoeletroquímica de corantes dispersos em efluente têxtil utilizando fotoanodos de Ti/TiO2

The degradation of disperses dyes in aqueous solution and in effluents from textile industry has been investigated by photoelectrocatalytic oxidation using nanoporous thin films electrodes of Ti/TiO2. Samples of dispersil black dye and dispersil blue dye after 300 min of photoelectrolyzed at applied potential of +1.0 V and UV irradiation exhibited 100% of discoloration and 90% and 64% reduction total organic carbon, respectively. The proposed method was applied with success in a textile industry effluent containing residues of these dyes, which after 300 min of treatment leads to reduction of 60% of COD and 64% removal of TOC.

Desenvolvimento de sistemas líquido-cristalinos empregando silicone fluido de co-polímero glicol e poliéter funcional siloxano

For the construction of the phase diagrams, the method of the aqueous titration was used. There were prepared 5 ternary diagrams, varying the surfactant and the oil phase. The liquid-crystalline phases were identified by polarized light microscopy. The formulations prepared with silicon glycol copolymer, polyether functional siloxane (PFS) and water (S1) and with diisopropyl adipate, PFS and water (S4) presented liquid-crystalline phases with lamellar arrangement. Moreover, after 15 days in hot oven (37 ºC), the formulations presented hexagonal arrangement, evidencing the influence of the temperature in the organization of the system.

Líquido iônico [bmim.PF6] como solvente: um meio conveniente para estudos por fotólise por pulso de laser

The spectroscopic behavior of thioxanthone and benzil (diphenylethanedione or dibenzoyl) in the ionic liquid [bmim.PF6] has been investigated employing the laser flash photolysis technique. Triplet-triplet absorption spectra for these carbonyl compounds in [bmim.PF6] are similar to those observed in organic solvents. The triplet lifetime for thioxanthone in desogygenated samples is very long (71 μs), whereas in oxygen-saturated solution is 500 ns, which indicates the low oxygen solubility in this solvent. For benzil, lifetimes of 10 μs in [bmim.PF6] and 3.8 μs in acetonitrile were obtained. The decay for triplet thioxanthone and benzil follows a clear first order kinetics in [bmim.PF6], from which one can conclude that triplet-triplet annihilation is not an important decay process in this solvent.

Daño oxidativo en la microalga Pseudokirchneriella subcapitata expuesta a aguas receptoras de un efluente minero en del Río Blanco (V Región, Chile)

In this investigation antioxidant response and toxicity of metals in receiving water effluent miner in the Blanco river in Pseudokirchneriella subcapitata was assessed. The catalase activity, lipid damage through Tbars, the growth rate of was determined. The result showed an inhibition of the growth rate of P. subcapitata which correlated with increased catalase activity and the lipid liperoxidation. These responses were correlated with the concentrations of copper and iron.

Aplicação de fotólise direta e UV/H2O2 a efluente sintético contendo diferentes corantes alimentícios

Food industries employ a lot of synthetic dyes in their products. Most of these dyes are very stable face to the conventional treatments. This work studied the use of advanced oxidation process (AOP) as an alternative to the conventional ones to degrade a synthetic food effluent (photolysis and UV/H2O2 in continuous reactor). The more efficient process was the UV/H2O2 and it presented decoloration and degradation energetic efficiency values equal to 30.775 kWh m-3 and 269.909 kWh m-3, respectively. The color reduction was 96.4% and COD decrease was 38.56%.

Avaliação (em escala laboratorial) da aplicação do processo eletrolítico em efluente de lagoa de estabilização de esgoto urbano

Physico-chemical and microbiological parameters were evaluated before and after applying an electrolytic process to effluents of a stabilization lagoon, in the presence or absence of "salt". Chlorine generation and bactericidal properties of the treatments were studied following two experiments. Effluent pH increased with electrolysis time. In the absence of "salt", 20 min electrolysis resulted in a COD (Chemical Oxygen Demand) reduction of 44%, along with ca. 99.9% (3 log10 cfu/mL) reduction in total coliforms, heterotrophic bacteria and Escherichia coli. These results indicated that the electrolytic process is a promising complementary technology to improve effluent quality for stabilization lagoons.

Uma revisão sobre o efeito Toms: o fenômeno onde macromoléculas atenuam a turbulência em um líquido

It is very well known that the addition of polymers to a liquid increases the shear viscosity of the solution. In other words, the polymer increases the dissipation of the flow energy. Contrarily, in turbulent flow, some particular macromolecules in very low concentration are able to produce large attenuation in the turbulence and thus, decreasing the dissipation of the energy. This article present a brief revision about macroscopic and molecular models used to explain this dynamic effect. Some of the experimental techniques used to quantify the attenuation of the turbulence and the main active substances are also discussed.

Avaliação físico-química de efluente gerado em biodigestor anaeróbio para fins de avaliação de eficiência e aplicação como fertilizante agrícola

The use of biodigester for basic and environmental sanitation has large demand in Brazil. A biodigester was built to treat conjunctly the human and pig feces and urine, regarding to its future application in rural small towns. The results show that the biodigester can reduce 90% of COD and BOD and, up to 99.99% of thermotolerant coliforms. The treated effluent has variable quantities of macro- and micro-nutrients; and organic matter. However, the concentration variability of the nutrients makes difficult a dosed application into soil. The soluble salts (mainly as Na+ form) make necessary a controlled use to avoid environmental degradation.

Tratamento do efluente do biodiesel utilizando a eletrocoagulação/flotação: investigação dos parâmetros operacionais

Electrocoagulation/flotation process was applied to treat biodiesel wastewater using aluminium electrodes. Firstly, a literature survey was conducted to choose the process variables and then, operational parameters including initial pH, electrode distance and reaction time were tested. Experimental results showed the best parameter that can be used in a factorial design for further studies. The results indicate that electrocoagulation/flotation is very efficient to reduce oil and grease, the effluent was very clear after treatment and small amount of sludge was produced.