Resumo em Inglês:

ABSTRACT Within the engineering and development of industrial bioprocesses, microbioreactors are microfluidic tools able to provide high-throughput screening tests in a fast and cheap manner by using small amounts of reagents. In addition, such tools are versatile and may allow a better controllability of parameters when compared to conventional bench-scale reactors. Consequentially, this technology has been gaining attention from the scientific community over the past years. In such scenario, this work provides a review study of the microbioreactor technology, outlining the origin, main concepts and principles of such technology, aiming to elucidate general questions that may emerge when studying such an approach. Past and current approaches are discussed aiming at drawing a comparative picture about such technology regarding future developments.

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ABSTRACT In this study, we investigated the outdoor production of a microalga C. vulgaris cultured in two different media under autotrophic cultivation: Bold Basal Medium (BBM) as the control and BBM supplemented with desalination concentrate (BBM + DC) using open raceway ponds (8 m2). Data were collected on the growth, biomass productivity and biochemical composition. The culture developed in BBM + DC showed a biomass productivity of 6.8 g m-2 day-1, while for the BBM control it was 8.5 g m-2 day-1. Intracellular protein was the main algal component (~28.6%), followed by carbohydrate + fiber (~26.0%) and lipids (~5.0%). The predominant fatty acids were mainly α-linolenic (~19.5%), palmitic (~16.5%) and linoleic (~10.0%) acids. This study demonstrates the feasibility of culturing C. vulgaris in an alternative medium based on DC in order to valorize the desalination wastewater through its application to algal mass production.

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ABSTRACT This work aimed to study the effect of the combination of four commercial enzymatic preparations (Celluclast 1.5 L, Viscozyme L, Ultrazym AFP, and Shearzyme 500 L) on the aqueous extraction yield of the oil from the pulp of Euterpe oleracea fruit. The enzymatic preparations were tested individually and in combinations of two, three and four, in triplicate. The negative control presented the lowest extraction yield (34.91%). The tests performed with the isolated enzymatic preparations presented an average increase in the extraction yield of approximately 30% compared to the negative control, confirming the important role of the enzymes in the extraction process. The tests performed with the combination of more than two enzymatic preparations increased the extraction yield by approximately 90% compared to the negative control, demonstrating the advantage of using combinations of enzymes. Among the different tests, those performed with the combination of three enzymatic preparations, including the cellulase class-type enzyme, Celluclast 1.5 L, stood out by presenting a high extraction yield (> 65%) and being statistically equal to the one using all four, which is interesting for the industry due to the reduced cost of the process.

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ABSTRACT A temporal analysis of fractal aggregates during water flocculation is presented. Water was prepared using kaolin solution and a non-intrusive image-based analysis method was used for two-dimensional fractal dimension assessment (dF). The dF values were determined for aggregates larger than 270 µm from 100 images taken in each combination of velocity gradients (Gf) and flocculation times (Tf). The Gf values of 20, 30, 40, 50 and 60 s-1 and Tf values of 2 to 180 minutes were studied, with a ΔTf of 1 minute for 2 ≤ Tf ≤ 10 minutes and a ΔTf of 5 minutes for 10 ≤ Tf ≤ 180 minutes. Results showed that dF tends toward stability from a Tf of 40 minutes, with distinct levels in each Gf. Further, dF values decrease from 1.80 to 1.35 for Gf from 20 to 60 s-1.

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ABSTRACT Natural water treatment requires emphasis on humic substances (HS) removal because of disinfection by-product formation possibilities. Thus, detailed research on HS structure and properties is necessary. Two model solutions of different origin were used in this study. A100, A200, A400, A870 and DEAE-cellulose anion exchange resins were used for the one-stage isolation of HS. Model solutions and eluates from the respective resins were subjected to filtration using regenerated cellulose 1, 5 and 10 kDa MWCO ultrafiltration membranes. The results allowed ranking of analyzed anionites according to the isolation capacity of HS: DEAE >> A870 > A100 > A400 > A200. Analysis of the HS molecular size distribution shows that hydrophilic compounds of low molecular weight (MW) are dominant in natural water, whereas in the Aldrich humic acid solution and in the eluates after each resin, large MW hydrophobic compounds are predominant.

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ABSTRACT Food waste (FW) has potential for use by means of anaerobic digestion (AD). However, some characteristics of FW affect process stability and methane (CH4) production. Using biochemical methane potential (BMP) tests, this study assessed the improvement of CH4 production and hydrolysis of FW by means of anaerobic co-digestion (AcoD) with swine manure (SM). Different FW:SM ratios were studied under conditions with (WN) and without (NN) nutrients. The highest CH4 production was obtained for the FW:SM 60:40 ratio in the WN and SN conditions with values of 72.87 and 62.83 mL CH4 g VS-1, respectively. This showed that AcoD of FW with SM presented synergistic effects, since increases of 27 (WN) and 13% (NN) were obtained in comparison with the mono-digestion of FW. There was also an improvement in the process stability (α index > 0.7), but there were no favorable effects with respect to the hydrolysis of FW.

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ABSTRACT In this study, the effects of operating time (t), current density (CD) and initial pH were investigated for soluble organic carbon (SOC) and total phosphorus (TP) removal from swine wastewater, pretreated in an UASB reactor, using an electrocoagulation process with aluminum (Al) and iron (Fe) electrodes. For the optimal conditions, Cu, Zn, Mn, Fe and Al removal, sludge production and energy consumption were evaluated. The removal efficiencies for the Al electrode were 78%, 96%, 84%, 99%, 65% and 84% for SOC, TP, Cu, Zn, Mn and Fe, respectively. For the Fe electrode the removal efficiencies were 57%, 96%, 81%, 99 % and 61% for SOC, TP, Cu, Zn and Mn, respectively. The sludge generated, energy consumption, and theoretical hydrogen yields were 5 g/L, 1-18 kWh/L and 0.7-8.5 kWh, respectively. The electrocoagulation process can be used for soluble organic carbon, phosphorus and metals removal from swine wastewater.

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ABSTRACT A mechanism to convert Fe(III) to Fe(II) by a reduction process could be a solution to the problem of selective separation of metals in extraction processes by using the ion-exchange process. The aim of this research was to reduce Fe(III) to Fe(II) present in leachate from nickel mining waste. Reducing agents used were sodium dithionite and sodium metabisulfite. The potential was decreased in order to quantify the minimum reducing agent that was necessary for conversion. Reaction time, pH, stirring speed and temperature were also studied. Results indicated dithionite was a better reducing agent than metabisulfite and complete conversion was possible by reducing the potential to 590mV at pH 0.5-2 and 240mV at pH 2.5. Stirring speed had no influence on the reduction process at 2 hours; however, conversion decreased after 24 hours, perhaps due to oxygen present in air. The analyses were conducted by ion chromatography and voltammetry.

Resumo em Inglês:

ABSTRACT Thin Film Composite Reverse Osmosis (TFC RO) membranes have undergone significant changes since inception; particularly the top polyamide layer has been tuned for optimal performance. The present paper demonstrates the novel approach to alter the polyamide membrane performance by subjecting it to ionic liquids. Ionic liquids 1-Butyl-3-Methylimidazolium Chloride [BMIM][Cl], 1-Methyl-3-Octylimidazolium Chloride [C8MIM][Cl] and 1-Butyl-3-Methylimidazolium Bromide [BMIM][Br] were used to alter the membrane performance. About a 6.5% increase in MgSO4 rejection and about an 87% increase in water-flux were noted when the membrane was subjected to 3000 mg/L [BMIM][Cl] after 2000 mg/L sodium hypochlorite each for 2 hours. Also, the decline in contact angle from 52.86o to 43.12o by this treatment demonstrated higher hydrophilicity. Atomic force microscope images showed a decline in surface roughness with the treatment. Scanning electron micrographs were taken to understand the changes in morphology of thin film composite reverse osmosis membranes with ionic liquid treatment. Attenuated total reflectance, infrared spectroscopy and nuclear magnetic resonance analysis were done to evaluate the changes in chemical structure and it was found that the treatment resulted in chemical structural modification of thin film composite reverse osmosis membranes with ionic liquid treatment.

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ABSTRACT The catalytic membrane reactors (CMR) were prepared using commercial Hollow Fiber Membranes of corundum with 4 nm or 1400 nm pores and impregnated with palladium. The tests performed were phenol hydrogenation, hydrogen peroxide generation to oxidize phenol by advanced oxidation processes and chromium (VI) reduction. Reactions were performed in aqueous solution, at mild temperature and under atmospheric pressure. For all tests, the hydrogen passed through the membrane to be activated with palladium. The test with phenol showed that, in the absence of oxygen, the activated hydrogen reacts with the organic matter, leading to the formation of hydrogenated products; in the presence of oxygen, active hydrogen reacts with oxygen to form hydrogen peroxide and subsequently hydroxyl radicals that attack the organic matter until its mineralization. Furthermore, the CMR is capable of reducing chromium (VI) to chromium (III). The CMRs of smaller pore size presented better performance in all reactions.

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ABSTRACT This work aimed to produce freeze-cast pellets of porous ceramic filters of alumina and kaolinite impregnated with silver nanoparticles and to test the efficiency of bactericidal effects. Silver nanoparticles were characterized by average particle size, zeta potential and TEM. After impregnation, leached water was analyzed by graphite furnace atomic absorption spectrometry (GFAAS) that showed an efficiency of more than 99.9% in silver impregnation. From SEM/EDS, it was possible to observe that the pellets have a homogeneous distribution of silver nanoparticles. A halo of inhibition detected by the disc diffusion test shows a strong bactericidal effect of the filters.

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ABSTRACT Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biodegradable polymer used for a wide range of applications, especially in biomedical and food industry, for which bioactive compound encapsulation is noteworthy. This work aimed to micronize PHBV by Solution Enhanced Dispersion by Supercritical Fluids technique and evaluate possible changes in polymer crystallinity. A 23 Central Composite Design with 3 central points was used to analyze the influence of pressure, temperature and PHBV concentration on particle size produced. Micronized particles were mostly spherical with sizes from 210 to 720 nm, and free of organic solvents. PHBV crystallinity degree was approximately 20% higher when polymer was processed at 8 MPa compared to that processed at 10 and 12 MPa, as well as to the raw polymer. Results suggest versatility in PHBV application according to SEDS process parameters and the possibility of its use in drug delivery systems.

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ABSTRACT Calcium oxide catalysts prepared from golden apple cherry snail shell (Pomacea canaliculata) via two steps - deproteination and calcination - were compared: the structure was characterized by XRD and XRF and morphology by SEM. In addition, the effects of reaction time, catalyst loading amount, methanol:oil molar ratio and reaction temperature on the biodiesel yield were measured. The optimum conditions for biodiesel production, 0.8 wt% catalyst loading, 12:1 methanol:oil molar ratio, 65 OC reaction and 6 h reaction time, gave a biodiesel up to 95.2%. Moreover, the catalyst demonstrated high stability, permitting reuse for up to four cycles with biodiesel yield falling by only 4%.

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ABSTRACT The presence of contaminants in diesel oil is severely controlled. These components affect the diesel properties, causing impacts on the emissions of pollutants and compromising its commercialization. The Brazilian legislation imposes the use of diesel S10. In this work, a hydrotreatment unit fed with multiple diesel streams was optimized using a phenomenological mathematical model. A three-phase model of a tricked-bed reactor was considered. The optimization of the process was performed with the interior point method considering the hydrodesulfurization reaction of diesel. It was proposed to minimize the operating cost, keeping the amount of sulfur in the final product below the maximum allowed value. The EMSO process simulator was used to model, simulate and optimize the hydrotreatment process. It was observed that the optimization strategy drove the contaminant content into the diesel S10 specification range, as well as reducing the process operating cost by increasing the feed temperature and hydrogen flowrate and adjusting the feed composition blend of the available diesel streams.

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ABSTRACT Haemophilus influenzae type b (Hib) vaccine is made up from its capsular polysaccharide (PRP). Low productivity of the polysaccharide during cell growth increases the final cost of this vaccine. Hib achieves low levels of cellular concentration in vitro due to the inhibition caused by acetate. The Akaike Information Criterion (AIC) was used in this work for selecting models of microbial growth. The application to the case of the multivariate models is outlined and the procedure is carried out using data from Hib cultures. From 4 models of biomass and 15 of acetate and PRP, one could be selected with great evidence for support. The use of AIC has shown to be robust and free of subjectivity, and it was able to define a kinetic model that is adequate for the cell growth and the production of its PRP over a wide range of culture conditions. The exponential inhibition factor was found to be the best for modelling inhibition of cell growth by acetate, while the hyperbolic factor was the best for inhibition of PRP formation. The acetate formation was found to have both growth associated and non-associated types. PRP formation was found to be only growth associated.

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ABSTRACT In liquid-liquid extraction contractors, mass transfer and stage efficiency are closely related to drop hydrodynamics. In the present study, hydrodynamic simulation of three standard liquid-liquid extraction systems recommended by the EFCE (European Federation of Chemical Engineering) has been investigated. Toluene/water, n-butyl acetate/water, and n-butanol/water with different drop diameters were considered in the simulations, representing systems with high, medium, and low interfacial tension respectively. In the current research, for the first time simulations have been carried out using the VOF-PLIC (Volume of Fluid - Piecewise Linear Interface Calculation) model, implementing two surface tension force models of CSS (Continuum Surface Stress) and CSF (Continuum Surface Force) as a source term in the momentum equation. Simulations have been carried out in an axisymmetric geometry with a moving droplet in the static zone. The stages of droplet acceleration, deformation, and stability in terms of shape and velocity have been captured through simulations. Simulation results show that the average relative error reduces by using the CSS model and the most enhanced effect is observed in the toluene/water system, followed by the n-butyl acetate/water and n-butanol/water systems, respectively. This is due to higher parasitic current effects in the highest surface tension system (toluene/water). The onset of oscillations in the toluene/water system was correctly predicted by the CSS model, while the CSF model could not. Droplet shapes, aspect ratio, terminal and transient velocity and streamlines were also reported in the two surface tension models and compared.

Resumo em Inglês:

ABSTRACT The process of solid circulation in an internally circulating fluidized bed (ICFB) having two or more chambers can be developed by applying unequal gas velocities in these chambers. Such a process is beneficial to several applications and provides the means for the energy transfer between the chambers in the ICFB. In this paper, a multi-fluid CFD model incorporating the kinetic theory of granular flow is used to simulate the hydrodynamic characteristics of a binary mixture of particles in an ICFB using ANSYS-Fluent software. The mixture is composed of two particles of different sizes but the same densities. The ICFB has two chambers named the reaction chamber (RC) and the heat exchange chamber (HEC), separated by a vertical central baffle. An increase in the RC gas velocity UR at constant HEC gas velocity UH results in an increase in the circulation rate of the binary mixture. The circulation rate of small particles GBs is found to be higher than that of the big particles GBb. Increasing the slot size causes a decrease in the pressure difference between the chambers and consequently decreasing the solid circulation rate in the ICFB. The mixture circulation rate also decreases when the mixture is richer in GBb particles than in GBs.

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ABSTRACT In this work, numerical approximations for solving the one dimensional Smoluchowski coagulation equation on non-uniform meshes has been analyzed. Among the various available numerical methods, finite volume and sectional methods have explicit advantage such as mass conservation and an accurate prediction of different order moments. Here, a recently developed efficient finite volume scheme (Singh et al., 2015) and the cell average technique (Kumar et al., 2006) are compared. The numerical comparison is established for both analytically tractable as well as physically relevant kernels. It is concluded that the finite volume scheme predicts both number density as well as different order moments with higher accuracy than the cell average technique. Moreover, the finite volume scheme is computationally less expensive than the cell average technique.

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ABSTRACT This work investigated the combination of agitation and aeration conditions in a bench-bioreactor to identify the optimal biosurfactant production from substrate based on beet peel and glycerol from a biodiesel process. Thus, a central composite rotatable design (CCRD) and responses were evaluated by response surface methodology (RSM) modeling. The optimal operation values determined were 200 rpm (agitation) and 0.5 vvm (aeration), reaching values of 1931.2 mg/L of crude biosurfactant concentration and 28.37 mN/m of surface tension. For the development of a mathematical model based on an artificial neural network (ANN), the experimental data from each run (CCRD) of the bioreactor were used. The results indicated a topology of 6-6-1 neurons with an excellent predictive capacity of biosurfactant concentration: dispersion plot with R2 of 0.995, and error criteria SSE of 0.31, MSE of 7.29×10-4 and RSME of 2.7×10-2. A soft sensor was then designed in an electronic spreadsheet, computing the biosurfactant production from secondary measurements. Furthermore, the produced biosurfactant showed the ability to remediate oil spreading, evaluated through the appearance of clear zones on the surface of water covered with oil, and also from high emulsification indexes obtained on most of the solvents tested, such as toluene (~65%).

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ABSTRACT Artificial neural networks (ANNs) were built to predict coagulant (Model I) and alkalizer (Model II) dosages given raw and treated water parameters from a water clarifying process. Different ANN architectures were tested and optimal results were obtained with [10-10-10-01] and [08-12-12-01] nodes of input, hidden and output layers for Models I and II, respectively. Two algorithms based on GUM-S1weredevelopedto evaluate the artificial neural network parameter uncertainty and the coverage interval of model outputs. The results show that these algorithms can provide a better set of parameters for the ANN compared with the traditional training method. The present research provides a unique unifying view that considers neural networks and uncertainty analysis in a well-documented industrial case study.

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ABSTRACT Microalgae oil of the species Chlorella protothecoides was obtained via a donation of the Soley Biotechnology Institute (SOLEYBIO) and characterized according to the fatty acid profile. Ethylic biodiesel was prepared using methods adapted by the research group. Analysis of acidity, water content, and density and viscosity temperature dependence (293.15 K to 368.15 K) were performed for the oil and ethylic biodiesel. The biofuel was characterized in terms of its flash and cloud points, heat capacity and cetane number. The properties studied were compared with conventional vegetable oils and biodiesel, presenting little differences and demonstrating the high viability of biodiesel from microalgae oil.

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ABSTRACT When the level of water reservoirs from Brazilian hydroelectric stations is low, additional thermal plants are turned on to complement the power of the national electric system. The fuels used in these plants are generally natural gas, fuel oil and coal. The objective of this work is to analyze energetically and exergetically a fuel oil thermal plant in operation in Brazil. Real industrial data were used in this analysis. The calculated total work of the turbine is 120.73 MW, which is close to the real value of 120 MW. The cycle energetic efficiency is 36.8% and the exergetic efficiency is 34.4%. The highest exergy destruction was found to be in the boiler (177.11 MW), followed by the high pressure turbine (13.37 MW), due to larger irreversibilities in the processes of these equipment. The exergetic analysis functioned as a complement to the energetic analysis, pointing out where the greatest irreversibilities and improvement potential are: in the boiler.

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ABSTRACT The alternative use of butanol in blends with diesel has attracted the attention of many researchers worldwide for its possibility to overcome some barriers observed for other lower chain alcohols. Viscosity, volatility and ignition quality are critical characteristics of a fuel intended for use in compression ignition engines. In this paper, the kinematic viscosity, atmospheric distillation and cetane number of butanol/diesel blends in proportions of up to 30 mass% were determined and compared with Brazilian diesel specifications. Two types of diesel matrices 10 ppm (S10) and 500 ppm (S500) sulfur and two butanol isomers (n- and iso-butanol) were tested. Results showed that both kinematic viscosity and cetane number were reduced with the increase of the butanol content in blends. Butanol provided an intense increase of the blend volatility, resulting in pronounced effects on the distillation curve shape, in relation to that observed for pure diesel.