Removal of high-molecular weight polycyclic aromatic hydrocarbons

Alternatives for the removal of high-molecular weight polycyclic aromatic hydrocarbons (HWM-PAH) from soil were tested by adding fertilizer or glycerol, as well as the combination of both. Experiments were carried out for 60 days in reactors containing a HWM-PAH-contaminated soil (8030 μg kg-1), accompanied by pH monitoring, humidity control and quantification of total heterotrophic bacteria and total fungus. Fertilizer addition removed 41.6% of HWM-PAH. Fertilizer and glycerol in combination removed 46.2%. When glycerol was added individually, degradation reached 50.4%. Glycerol also promoted the increase of degradation rate during the first 30 days suggesting the HMW-PAH removal occurred through cometabolic pathways.

Atual estágio de desenvolvimento da tecnologia GTL e perspectivas para o Brasil

Although the production of liquid fuels from coal, natural gas (CTL and GTL processes) and other carbon sources has been discovered 90 years ago, the interest was renewed in the last years motivated by stranded gas reserves and by petroleum market instability. This review intends to show the scenario of these technologies nowadays, discussing the applied technologies, the steps in an industrial plant, the ways to produce syngas and liquid fuels, the catalysts used, the type of reactors and the operating plants with their respective capacities, besides the technical, economical and environmental viability, challenges and perspectives for Brazil.

Determinação de parâmetros cinéticos em fluxo com câmara de gradiente e deteção espectrofotométrica: aplicação à reação entre o violeta de cristal e o ião hidróxido

A didactic experiment is proposed aimed to extend the Flow Injection Analysis (FIA) based methodology to the area of physical chemistry/chemical reactors for undergraduate labs. Our prime objective was to describe the use of a gradient chamber for determination of the rate constant for the reaction between crystal violet and the hydroxide ion. The study was complemented by determining the effect of temperature on the rate constant. The kinetic parameters, activation energy and reaction rate constant are determined based on an assumption of rate orders. The main didactic advantages of the proposed experimental set-up are the use of less reagents, contributing to a more environmental friendly experiment. The experiment illustrates also the reduction of associated errors and time by using automated analysis owing to decreased operator manipulation.

Imobilização de lacase de Aspergillus sp. em quitosana e sua aplicação na bioconversão de fenóis em reatores de leito fixo

The immobilization of laccase on chitosan by cross-linking and application of the immobilized laccase in the bioconversion of phenolic compounds in batch and fixed bed reactors were studied. The process for immobilization of enzyme was optimized using a rotational central composite design. The optimized conditions to generate immobilized laccase with maximal activity were determined to be a glutaraldehyde concentration of 1.0% (v/v), a pH of 6.0, an immobilization time of 5.0 hours and an enzyme concentration of 5.2 g L-1. In packed bed reactors, the activity of the immobilized enzyme is maintained for a longer time in the bioconversion of 2,6-dimethoxyphenol than in the bioconversion of syringaldazine.

Advances in ethanol reforming for the production of hydrogen

Catalytic steam reforming of ethanol (SRE) is a promising route for the production of renewable hydrogen (H2). This article reviews the influence of doping supported-catalysts used in SRE on the conversion of ethanol, selectivity for H2, and stability during long reaction periods. In addition, promising new technologies such as membrane reactors and electrochemical reforming for performing SRE are presented.

Desenvolvimento de reator tipo "dip catalyst" para filmes poliméricos contendo nanopartículas de metais de transição

This article describes the development of a new catalytic reactor designed to operate with nanoparticle-embedded polymer thin films. Stabilization of metal nanoparticles in films that serve as catalysts in organic reactions is relatively new; therefore, the development of reactors to facilitate their use is necessary. We describe in detail the preparation of the GDCR reactor-type "dip catalyst" and its evaluation in the Suzuki - Miyaura cross-coupling reaction of phenylboronic acid and 4-bromoanisole catalyzed by palladium nanoparticle-embedded cellulose acetate thin film (CA/PD(0)). Compared with earlier prototypes, GDCR reactor showed excellent results when operating with CA/PD(0) thin films.

COMPARAÇÃO E CONSTRUÇÃO DE REATORES DE "MILD" E "HARD ANODISATION" PARA FABRICAÇÃO DE ALUMINA ANÓDICA POROSA

The mild anodization (MA) reactor is exemplified for its operational simplicity and its excellent control over the experimental parameters that are involved in the anodization process. This method provides porous anodic alumina films with a regular cell-arrangement structure. This offers a better cost-benefit ratio than the other equipment configurations that are used to fabricate nanoporous structures (i.e., ion beam lithography). Conversely, the hard anodization (HA) reactor produces oxides at a rate that is 25 to 35 times faster than the MA reactor. The produced oxides also have greater layer thicknesses and interpore distance, and with a uniform nanopore spatial order (> 1000). In contrast to MA reactors, the construction of an HA reactor requires special components to maintain anodisation at a high potential regime. Herein, we describe and compare both reactors from a technical viewpoint.

Logistic regression to estimate the welfare of broiler breeders in relation to environmental and behavioral variables

The increasing demand of consumer markets for the welfare of birds in poultry house has motivated many scientific researches to monitor and classify the welfare according to the production environment. Given the complexity between the birds and the environment of the aviary, the correct interpretation of the conduct becomes an important way to estimate the welfare of these birds. This study obtained multiple logistic regression models with capacity of estimating the welfare of broiler breeders in relation to the environment of the aviaries and behaviors expressed by the birds. In the experiment, were observed several behaviors expressed by breeders housed in a climatic chamber under controlled temperatures and three different ammonia concentrations from the air monitored daily. From the analysis of the data it was obtained two logistic regression models, of which the first model uses a value of ammonia concentration measured by unit and the second model uses a binary value to classify the ammonia concentration that is assigned by a person through his olfactory perception. The analysis showed that both models classified the broiler breeder's welfare successfully.

Establishment of anammox process in sludge samples collected from swine wastewater treatment system

The high load of nitrogen present in swine wastewater is one of the biggest management challenges of the activity. The Anammox process emerges as a good alternative for biological removal of nitrogen. This study aims to acclimate sludge collected from swine effluent treatment systems to establish the Anammox process. Two sludge samples were collected at Embrapa Swine and Poultry, Concordia - SC, Brazil, one from the bottom of an inactive anaerobic pond (inoculum A) and another from an aeration tank (inoculum B). Both were acclimated until the depletion of NO3-N, being subsequently inoculated in two reactors (Reactor A - Inoculum A and Reactor B - Inoculum B). The Reactor A showed activity after 110 days of operation, while the Reactor B needed 170 days. The difference in the start-up time could be explained by the different environmental conditions to which each sludge was submitted. FISH and PCR analyses confirmed the presence of microorganisms with Anammox activity, demonstrating that the sludge of swine wastewater treatment systems is a good source of inoculum for the development of the Anammox process.

Estimating the most important criteria for hatching eggs as function of broiler breeders age

This research aimed to compare two female broiler breeder ages during the incubation period regarding management using the Analytic Hierarchy Process method (AHP). This method is characterized by the possibility of analyzing a multicriteria problem and assists a decision making. This study was carried out on a commercial hatchery located in São Paulo, Brazil. Two ages of broiler breeder (42 and 56 weeks) were compared relative to production rate. Production index data were the same in both ages and were submitted to multicriteria decision analysis using the AHP method. The results indicate that broiler breeders of 42 weeks presented better performance than those of 56 week-old. The setter phase (incubation) is more critical than the hatcher. The AHP method was efficient for this analysis and can serve as a methodological basis for future studies to improve the hatchability of broilers eggs.

Prevalence of antibodies against chicken anaemia virus (CAV) in broiler breeders in Southern Brazil

Chicks infected during the first two weeks of life with chicken anaemia virus (CAV) manifest clinical disease that can be avoided if the breeder hens transfer enough antibodies to their progeny. The objective of the present work was to establish the prevalence and titer of anti-CAV antibodies in some Brazilian broiler hen breeder flocks and verify in which phase of life the birds were infected. A total of 1,709 serum samples from 12 broiler hen flocks vaccinated against CAV and 64 unvaccinated flocks were analyzed for CAV antibodies with an enzyme-linked immunosorbent assay (ELISA). All non-vaccinated breeder flocks were found to be infected with CAV, with 89% of the hens tested presenting antibodies, 52% of these with titers considered high enough to protect their progeny against CAV infection. Likewise, all vaccinated hens had antibody titer to CAV capable of conferring protection to their progeny. Thus, vaccination of hens seems capable of conferring protection to chicks against clinically apparent CAV-associated disease.

Static pressure and wall shear stress distributions in air flow in a seven wire-wrapped rod bundle

An experimental investigation is performed in a turbulent flow in a seven wire-wrapped rod bundle, mounted in an open air facility. Static pressure distributions are measured on central and peripheral rods. By using a Preston tube, the wall shear stress profiles are experimentally obtained along the perimeter of the rods. The geometric parameters of the test section are P/D=1.20 and H/D=15. The measuring section is located at L/D=40 from the air inlet. It is observed that the dimensionless static pressure and wall shear stress profiles are nearly independent of the Reynolds number and strongly dependent of the wire-spacer position, with abrupt variations of the parameters in the neighborhood of the wires.

Experimental analysis of pressure drop and flow redistribution in axial flows in rod bundles

Fuel elements of PWR type nuclear reactors consist of rod bundles, arranged in a square array, and held by spacer grids. The coolant flows, mainly, axially along the rods. Although such elements are laterally open, experiments are performed in closed type test sections, originating the appearance of subchannels with different geometries. In the present work, utilizing a test section of two bundles of 4x4 pins each, experiments were performed to determine the friction and the grid drag coefficients for the different subchannels and to observe the effect of the grids in the crossflow, in cases of inlet flow maldistribution.

Thermalhydraulic behavior of electrically heated rod during a critical heat flux transient

In nuclear reactors, the occurrence of critical heat flux leads to fuel rod overheating with clad fusion and radioactive products leakage. To predict the effects of such phenomenon, experiments are performed using electrically heated rods to simulate operational and accidental conditions of nuclear fuel rods. In the present work, it is performed a theoretical analysis of the drying and rewetting front propagation during a critical heat flux experiment, starting with the application of an electrical power step from steady state condition. After the occurrence of critical heat flux, the drying front propagation is predicted. After a few seconds, a power cut is considered and the rewetting front behavior is analytically observed. Studies performed with various values of coolant mass flow rate show that this variable has more influence on the drying front velocity than on the rewetting one.

Detection of Horizontal Two-Phase Flow Patterns Through a Neural Network Model

One of the main problems related to the transport and manipulation of multiphase fluids concerns the existence of characteristic flow patterns and its strong influence on important operation parameters. A good example of this occurs in gas-liquid chemical reactors in which maximum efficiencies can be achieved by maintaining a finely dispersed bubbly flow to maximize the total interfacial area. Thus, the ability to automatically detect flow patterns is of crucial importance, especially for the adequate operation of multiphase systems. This work describes the application of a neural model to process the signals delivered by a direct imaging probe to produce a diagnostic of the corresponding flow pattern. The neural model is constituted of six independent neural modules, each of which trained to detect one of the main horizontal flow patterns, and a last winner-take-all layer responsible for resolving when two or more patterns are simultaneously detected. Experimental signals representing different bubbly, intermittent, annular and stratified flow patterns were used to validate the neural model.