Resumo em Inglês:

Methylamine and sulfate are compounds commonly found in wastewaters. This study aimed to determine the methanogenic potential of anaerobic reactors containing these compounds and to correlate it with their microbial communities. Batch experiments were performed at different methylamine/sulfate ratios of 0.71, 1.26 and 2.18 (with respect to mass concentration). Control and experimental runs were inoculated with fragmented granular sludge. The maximum specific methane formation rates were approximately 2.3 mmol CH4 L-1 g TVS-1 day-1 for all conditions containing methylamine, regardless of sulfate addition. At the end of the experiment, total ammonium-N and methane formation were proportional to the initial concentrations of methylamine. In the presence of methylamine and sulfate, Firmicutes (46%), Deferribacteres (13%) and Proteobacteria (12%) were the predominant phyla of the Bacteria domain, while Spirochaetes (40%), Deferribacteres (17%) and Bacteroidetes (16%) predominated in the presence of methylamine only. There was no competition for methylamine between sulfate-reducing bacteria and methanogenic archaea.

Resumo em Inglês:

Pequizeiro (Caryocar brasiliense Camb) fruits have been evaluated as a potential raw material for the newly established biodiesel industry. This scenario demands applications using the solid co-product derived from the extraction of pequi oil, called cake or meal. This study analyses the acid hydrolysis of carbohydrates present in the pequi meal in order to obtain fermentable sugars and evaluates their conversion to bioethanol. There was 27% starch in the pequi meal. The use of a CCRD experimental design type to study the acid saccharification of pequi meal results in 61.6% conversion of its starch content to reducing sugars. Positive and significant linear effects were observed for H2SO4 concentration and temperature factors, while the quadratic effect of H2SO4 concentration and the linear effect of solid-liquid ratio were negative. Even, with non-optimized fermentative condition using 1% of dried baker's yeast in conical flasks, it was possible to obtain a value equivalent to 53 L of ethanol per ton of hydrolyzed pequi meal.

Resumo em Inglês:

In order to develop cost effective processes for converting biomass into biofuels, it is essential to improve enzyme production yields, stability and specific activity. In this context, the aim of this work was to evaluate the concentration of two enzymes involved in the hydrolysis of biomass, endoglucanase and xylanase, through precipitation. Statistical experimental design was used to evaluate the influence of precipitant agent concentration (ammonium sulfate and ethanol), aging time, and temperature on enzyme activity recovery. Precipitant agent concentration and aging time showed a statistically significant effect at the 95% confidence level, on both enzyme activity recoveries. The recovery of endoglucanase with ammonium sulfate and ethanol reached values up to 65 and 61%, respectively. For xylanase, the recovery rates were lower, 27 and 25% with ammonium sulfate and ethanol, respectively. The results obtained allowed the selection of the variables relevant to improving enzyme activity recovery within operational conditions suitable for industrial applications.

Resumo em Inglês:

A Plackett-Burman experimental design was used to evaluate seven medium components added to molasses (corn steep liquor, sodium acetate, magnesium sulfate, manganese sulfate, ammonium citrate, potassium phosphate and Tween 80). Corn steep liquor (CSL), K2HPO4 and Tween 80 increased lactic acid production. The concentrations of these three components as well as the molasses were further optimized using the response surface method. A maximal lactic acid production of 94.8 g L-1 was obtained when the concentrations of molasses, CSL, K2HPO4 and Tween 80 were 193.50 g L-1, 37.50 mL L-1, 2.65 g L-1 and 0.83 mL L-1, respectively. However, in both shaker and bioreactor, approximately one fourth of the sugar added initially was not utilized after 48 hours of fermentation. Future studies that consider high conversion of sugar into final product as well as high volumetric productivity are necessary to improve the fermentation process and to reduce the downstream costs.

Resumo em Inglês:

The proportion of nitrogenated compounds such as carbazole in heavy fractions of crude oil is higher in Brazil than in other parts of the world. The degradation of this compound by microorganisms has already been described for bacteria such as Pseudomonas stutzeri ATCC 31258. Assays were undertaken to assess the influence of different carbazole concentrations on cell growth, carbazole degradation and the formation of anthranilic acid (an intermediate in the carbazole degradation pathway). The results indicated that there was an accumulation of anthranilic acid in the medium with the higher concentration of substrate (10 g/L), which could be related to the inhibition of Pseudomonas stutzeri growth in an excess of carbazole. With 1 g/L of carbazole, growth was found to be ten times greater (0.37 g dry cell weight/L) and there was no accumulation of anthranilic acid (formation of around 7 mg/L), with complete carbazole degradation after three days.

Resumo em Inglês:

C-Phycocyanin is a natural blue dye used in food and pharmaceutical industry. In the present study, a simple and efficient method to extract C-phycocyanin from Spirulina platensis wet biomass is reported. The extractions were carried out using six different methods, including chemical (organic and inorganic acid treatment), physical (freezing and thawing, sonication, homogenization) and enzymatic (lysozyme treatment) methods. The extraction using ultrasonic bath in the presence of glass pearls in the biomass proved to be the most efficient method, 56% higher than using freezing and thawing (the method most frequently used), and presented a extraction yield of 43.75 mg.g-1 and a C-phycocyanin concentration of 0.21 mg.mL-1.

Resumo em Inglês:

The present investigation was aimed at determining the impact of the macrolide antibiotic Tylosin in reduced HRT at constant organic loading rate (OLR) by varying feed substrate concentration in an up-flow anaerobic stage reactor (UASR). The antibiotic concentration was maintained at 200 mg.L-1, at constant OLR of 1.88 kg COD.m-3.d-1, by varying feed substrate concentration to the UASR and the HRT was decreased gradually from 4 to 1 d. Throughout the operation period, brewery wastewater was used as simple feed substrate to elevate the concentration of easily biodegradable carbon in comparison with the concentrations of more recalcitrant Tylosin substrate. The reactor alkalinity was controlled in all the stages of UASR by adding 1000 - 2000 mg.L-1 CaCO3. Results showed the total COD removal efficiency at 4 d HRT was around 92%, after which point there was a slight decrease at 3 and 2 d HRT (average 82%), and this was reduced further (average 77%) at a HRT of 1 d. The UASR showed stable operation with effluent volatile fatty acid (VFA) less than 300 mg.L-1 throughout the experimental period (HRT 4 - 1 d). Moreover, the average methane yield (CH4.kg CODr-1) showed a relatively constant profile and was largely unaffected by HRT in all the stages of UASR. These results show that bacteria were readily adapted to wastewater containing Tylosin at lower HRTs and did not affect the reactor performance substantially.

Resumo em Inglês:

Removal of nitrates, sulfate and Zn(II) ions from aqueous solutions through adsorption onto biopolymeric alginate/clinoptilolite-rich tuff pellets was studied by using an equilibrium batch technique. The idea of this approach of biosorbent fabrication is to promote the native zeolite adsorption performance and thus to prepare more efficient amphoteric tailor-made products for specific environmental targets. A flexible component, i.e., alginate biopolymer, and a rigid component (pulverized) zeolite were crosslinked using Fe(III) and Ca(II) chlorides, additively. The extent of adsorption was found to be considerably higher than with the other mostly natural adsorbents examined towards similar pollutants. The equilibrium adsorption data for the above pollutants were satisfactorily fitted to Freundlich and Langmuir isotherms, respectively. According to the linscale SAXS pattern, there was a strong background visible, which may indicate the presence of a considerable amount of biopolymeric phase in the composite samples analysed. Scanning Tunneling, Electron and Atomic Force Microscopies helped visualize their surface texture and morphology.

Resumo em Inglês:

High water consumption and water scarcity make industrial wastewater reuse necessary, especially in those industries characterized by polluted effluents such as welding electrode manufacturing industries. The present paper investigates the coupling of coagulation-flocculation with nanofiltration (NF) to recycle water and reuse it in the process. First, the effect of different concentrations of a mixture of alum (Al2(SO4)3.18H2O) and ferric chloride (FeCl3) on the pretreatment process was closely studied. Then the NF process was applied for complementary treatment. The NF results show that, by increasing both flow rate and transmembrane pressure (TMP), permeate flux is increased. The NF results also show that the COD value decreases below 2 mg/l, TDS rejection approaches 82%, turbidity decreases below 1 NTU and the hardness is lower than the factory constraint (100 mg/l as CaCO3), allowing the reuse of the treated wastewater in the process.

Resumo em Inglês:

During the pneumatic conveying of plastic pellets, it has been observed that materials with similar physical characteristics may develop a substantial difference in pressure drop. In this work, the pressure drop in a particle-laden 2.7 meter long horizontal channel with circular cross-section is presented from an experimental perspective. Experiments are carried out for cylindrical polystyrene beads with an average diameter of 3.2 mm and mass loadings of 0.06 to 0.11 (kg particles/kg gas). The air mass flow rate was studied in the range from 0.085 kg/s to 0.170 kg/s. The pressure drop curve is shown as a function of air velocity and particle load. Response surface methodology showed high statistical significance for air velocity, particle load and their cross-relation.

Resumo em Inglês:

The experimental conditions were optimized for the synthesis of amorphous SiO2 particles by the reaction of neutralization of sodium silicate solution with H2SO4 solution. Amorphous SiO2 particles were characterized by XRD, FT-IR, FE-SEM, EDS and microelectrophoresis. The amorphous peak was located at 2θ = 21.8º in the XRD pattern. Primary SiO2 particles were ~ 15 to ~ 30 nm in size and they aggregated into bigger particles. Amorphous SiO2 particles showed a specific surface area up to 130 m²g-1, dependent on the parameters of the precipitation process. The EDS spectrum of amorphous SiO2 particles did not show contamination with sulfate or other ions, which cannot be excluded in traces. pHzpc =1.7 was obtained by microelectrophoresis.

Resumo em Inglês:

The yield of thiophene from furan and H2S was investigated using selected catalyst carriers (alumina, active carbon and silica gel) and active ingredients (silicotungstic, phosphomolybdic and phosphotungstic acids) to obtain the optimized synthesis parameters. The experimental results indicated that the yield of thiophene reached a maximum when the supported catalyst was alumina and the active ingredient was phosphotungstic acid. Furthermore, the reaction mechanism of the optimized reactive system was studied by the density functional theory (DFT) method. The calculated energy profile indicated that there were four transition states in the reaction process.

Resumo em Inglês:

This work explores a two-step, complexity reducing methodology, to analyze heat integration opportunities of an existing Olefins Plant, identify and quantify reduction of energy consumption, and propose changes of the existing heat exchanger network to achieve these goals. Besides the analysis of plant design conditions, multiple operational scenarios were considered to propose modifications for handling real plant operation (flexibility). On the strength of plant complexity and large dimension, work methodology was split into two parts: initially, the whole plant was evaluated with traditional Pinch Analysis tools. Several opportunities were identified and modifications proposed. Modifications were segregated to represent small and independent portions of the original process. One of them was selected to be re-analyzed, considering two scenarios. Reduction of problem dimension allowed mathematical methodologies (formulation with decomposition, applying LP, MILP and NLP optimization methods) to synthesize flexible networks to be applied, generating a feasible modification capable of fulfilling the proposed operational scenarios.

Resumo em Inglês:

Fluidized-bed Catalytic Cracking (FCC) is a process subject to frequent variations in the operating conditions (including feed quality and feed rate). The production objectives usually are the maximization of LPG and gasoline production. This fact makes the FCC converter unit an excellent opportunity for real-time optimization. The present work aims to apply a dynamic optimization in an industrial FCC converter unit, using a mechanistic dynamic model, and to carry out a numerical analysis of the solution procedure. A simultaneous approach was used to discretize the system of differential-algebraic equations and the resulting large-scale NLP problem was solved using the IPOPT solver. This study also does a short comparison between the results obtained by a potential dynamic real-time optimization (DRTO) against a possible steady-state real-time optimization (RTO) application. The results demonstrate that the application of dynamic real-time optimization of a FCC converter unit can bring significant benefits in production.

Resumo em Inglês:

The technique of experimental design is used on an ethylene polymerization process model in order to map the feasible optimal region as preliminary information for process optimization. Through the use of this statistical tool, together with a detailed deterministic model validated with industrial data, it is possible to identify the most relevant variables to be considered as degrees of freedom for the optimization and also to acquire significant process knowledge, which is valuable not only for future explicit optimization but also for current operational practice. The responses evaluated by the experimental design approach include the objective function and the constraints of the optimization, which also consider the polymer properties. A Plackett-Burman design with 16 trials is first carried out in order to identify the most important inlet variables. This reduces the number of decision variables, hence the complexity of the optimization model. In order to carry out a deeper investigation of the process, complete factorial designs are further implemented. They provide valuable process knowledge because interaction effects, including highly non-linear interactions between the variables, are treated methodically and are easily observed.

Resumo em Inglês:

The ethanol production by Pichia stipitis was evaluated in a stirred tank bioreactor using semi-defined medium containing xylose (90.0 g/l) as the main carbon source. Experimental assays were performed according to a 2² full factorial design to evaluate the influence of aeration (0.25 to 0.75 vvm) and agitation (150 to 250 rpm) conditions on ethanol production. In the studied range of values, the agitation increase and aeration decrease favored ethanol production, which was maximum (26.7 g/l) using 250 rpm and 0.25 vvm, conditions that gave a volumetric oxygen transfer coefficient (kLa value) of 4.9 h-1. Under these conditions, the ethanol yield factor, ethanol productivity, and the process efficiency were 0.32 g/g, 0.32 g/l.h, and 63%, respectively. These results are promising and contribute to the development of a suitable process for ethanol production from xylose by Pichia stipitis.

Resumo em Inglês:

Heat transfer of a silver/water nanofluid in a two-phase closed thermosyphon that is thermally enhanced by magnetic field has been predicted by an optimized artificial Neural Network. Artificial neural network is a technique with flexible mathematical structure that is capable of identifying complex non-linear relationships between input and output data. A multi-layer perception neural network was used to estimate the thermal efficiency and resistance of a thermosyphon during application of a magnetic field and using nanoparticles in the water as the working fluid. The magnetic field strength, volume fraction of nanofluid in water and inlet power were used as input parameters and the thermal efficiency and thermal resistance were used as output parameters. The results were compared with experimental data and it was found that the thermal efficiency and resistance estimated by the multi-layer perception neural network are accurate. The GA-ANN (Genetic Algorithm-Artificial Neural network) predicts the thermosyphon behavior correctly within the given range of the training data. In this study, a new approach for the auto-design of neural networks, based on a genetic algorithm, has been used to predict collection output of a closed thermosyphon.

Resumo em Inglês:

Two bentonite clays with different mineralogical compositions from Mendoza, Argentine, were activated with H2SO4 solutions of 4 and 8 N at 90ºC for 3.5 hours. This treatment affected clay structural properties, as was shown by thermogravimetry, infrared spectrometry and chemical analysis. Bleaching efficiency for sunflower oil was strongly dependent on the acid concentration used for clay activation. The samples have bleaching capacity comparable to that observed with a commercial adsorbent standard. The mineralogical composition of natural clays influenced the properties of the activated clays.