Resumo em Inglês:

The conception and development on a rational basis of a new configuration of anaerobic fixed-bed bioreactor for wastewater treatment, the horizontal-flow anaerobic immobilized sludge (HAIS) reactor, is presented. Such a reactor containing immobilized sludge in polyurethane foam matrices was first assayed for treating paper industry wastewater. A very short start-up period was observed and the reactor achieved stable operation by the eighth day. Afterwards, fundamental aspects of the process were investigated in order to obtain a rational basis for HAIS reactor design. A sequence of experiments was carried out for evaluating the cell wash-out from polyurethane foam matrices, the liquid-phase mass transfer coefficient and the intrinsic kinetic parameters, besides the hydrodynamic flow pattern of the reactor. The knowledge of such fundamental phenomena is useful for improving the reactor’s design and operation. Besides, these fundamental studies are essential to provide parameters for simulation and optimization of processes that make use of immobilized biomass

Resumo em Inglês:

Vinasse, a residual substance left after sugarcane alcohol distillation, represents a major environmental problem for the ethanol industry. No one has found a convenient and economical disposal solution for this black-reddish (Vinasse presents a light brown color and a low total solids content, from 2-4%, when it is obtained from straight sugarcane juice and a black-reddish color and total solids ranging from 5-10% when it is obtained from sugarcane molasses, which is the case of the vinasse used in this study.), viscous, high B.O.D. and acid material which is produced in quantities up to 15 times larger than those of the alcohol itself. This research investigated and developed the basic technology of on-site disposal of vinasse by combustion. Besides the clean ecological benefit, this method promotes energy savings and extra benefits when rich potassium vinasse ash is commercialized. Basic research was conducted using the facilities in the Combustion Laboratory (Mechanical Engineering Dept. at the Louisiana State University Campus in Baton Rouge). This research on vinasse combustion consisted of determining heating values, composition, and flame characteristics through combustion tests. Initially only vinasse was used in different solid concentrations and later emulsions were prepared using vinasse and # 6 fuel oil

Resumo em Inglês:

A data bank of parameters for two expressions for the temperature-dependence of the attractive coefficient, <FONT FACE="Symbol">a</font> (T), of the Peng-Robinson equation of state was compiled for 468 pure substances of varied polarity. The performances of the two expressions, a two-parameter form by Melhem et al. (1989) and a three-parameter form by Almeida et al. (1991) were compared through the root mean square (rms) and maximum (max) deviations in the prediction of the vapor pressure for these substances. The results show the superiority of the three-parameter form

Resumo em Inglês:

The equations of the method based on the maximum likelihood principle have been rewritten in a suitable generalized form to allow the use of any number of implicit constraints in the determination of model parameters from experimental data and from the associated experimental uncertainties. In addition to the use of any number of constraints, this method also allows data, with different numbers of constraints, to be reduced simultaneously. Application of the method is illustrated in the reduction of liquid-liquid equilibrium data of binary, ternary and quaternary systems simultaneously

Resumo em Inglês:

This work deals with enzymatic hydrolysis of babassu oil by immobilized lipase in membrane reactors of two types: a flat plate nylon membrane and a hollow fiber polyetherimide membrane on which surface commercial lipases were immobilized by adsorption. Experiments conducted in the hollow fiber reactor showed that during the immobilization step enzyme adsorption followed a sigmoid model, with a maximum adsorption equilibrium time of 30 minutes. Concerning the hydrodynamics of the liquid phases, the results indicate that main diffusional limitations occurred in the organic phase. The amount of protein immobilized and the maximum productivity were, respectively, 1.97 g/m2 and 44 <FONT FACE="Symbol">m</font> molH+/m2.s for the hollow fiber and 1.2 g/m2 and 56 <FONT FACE="Symbol">m</font> molH+/m2.s for the flat and plate membrane. Both reactors were able to perform the hydrolysis reaction, while maintaining absolute separation of the two phases by the membrane

Resumo em Inglês:

In this paper we present a new sequential quadratic programming SQP algorithm that does not need any preprocessing phase. Its main features consist of not enforcing the Hessian to be positive definite and of dealing with infeasible QP problems in a novel way. The linearized constraints are analyzed and all those that do not belong to the minimal representation of the feasible region are eliminated. In the approach used the convergence rate of the algorithm may be adjusted by the user by properly selecting some tuning parameters that are also used to improve the robustness of the algorithm. The SQP code presented here is also able to deal with bound constraints that may be linearly dependent on the linearized equality or original constraints. The algorithm is shown to be robust and to perform well for small to medium-sized problems

Resumo em Inglês:

Brass coupons were installed in a bypass in an industrial cooling water that uses seawater. The metal samples were removed at 15, 30, 45, and 60-day intervals for quantitative and qualitative analyses of the microorganisms constituting the biofilm adhering to the metal surface. After 15 days of exposure, a biofilm had already been generated which contained aerobic and anaerobic microorganisms. The aerobic bacteria were the most stable in relation to quantity, followed by the fungi. Anaerobic microorganisms, as well as sulfate-reducing bacteria, were present at higher concentrations. Variations in sulfide contents were observed in the biofilm. Analysis by scanning electron microscopy revealed microalgae, bacteria, filaments, and corrosion products as constituents of the biofilm adhering to the surface of the metal. After the biofilms were scraped off the brass samples, evidence of corrosion was observed on the metal surface

Resumo em Inglês:

The effect of pH (from 4.0 to 5.0), temperature (T) (from 30 oC to 40 oC) and dissolved oxygen concentration (DO) (from 0.2 to 6.0 mg O2/L) on glucose 6-phosphate dehydrogenase (G6PDH) (EC 1.1.1.49) and Invertase (EC 3.2.1.26) formation by S. cerevisiae were studied. The best culture conditions for G6PDH and Invertase formation were: 2.55 L culture medium (yeast extract, 3.0 g/L; 5peptone, 5.0 g/L; glucose, 2.0 g/L; sucrose, 15.0 g/L; Na2HPO4.12 H2O, 2.4 g/L; (NH4)2SO4, 5.1 g/L and MgSO4. 7H2O, 0.075 g/L); 0.45 L inoculum (0.70 g dry cell/L); pH = 4.5; T = 35 oC and DO = 4.0 mg/L. G6PDH was highly sensitive to pH, T and DO variation. The increase in G6PDH production was about three times when the DO ranged from 0.2 to 4.0 mg O2/L. Moreover, by shifting pH from 5.0 to 4.5 and temperature from 30 oC to 35 oC, G6PDH formation increased by 57% and 70%, respectively. Invertase activity (IA) of whole cells decreased at least 50% at extremes values of DO (2.0 and 6.0 mg O2/L) and pH (4.0 and 5.0). Furthermore, IA oscillated during the fermentation due to the glucose repression/derepression mechanism