Abstract Lipids extracted from microalgae for biofuel production have drawn the attention of researchers. Various methods for quantification of neutral lipids, such as solvent extraction or gravimetric, require a large volume of sample and are time-consuming. In this work, Nile Red was employed to evaluate the lipid content in microalgae Scenedesmus sp. through 2D fluorescence spectroscopy using chemometric modeling with a selection of wavelength pairs reducing the variable numbers. Cultivation of microalgae for 10 days was performed. Samples were taken starting after the 5th day of cultivation. Microalgae samples were dried using an oven with tangential airflow and the conventional Bligh and Dyer method for lipid extraction was employed. Before the measurement of fluorescence, the samples were diluted in ethanol at 40°C for 10 minutes, and then Nile Red solution (10 µg/mL ethanol) was added. The results of lipid quantification using the proposed technique achieved mean absolute percentage error (MAPE) lower than 5% and correlation coefficients around 0.99 in the test phase. Linear models using four excitation-emission pairs of fluorescence were fitted and were selected based on Pure Spectral Chemometric Modelling (PSCM). The method for lipid quantification using predictive linear models and 2D fluorescence proved to be robust and fast (requiring less than 30 min) compared to the conventional gravimetric method (which takes at least 5 hours) to obtain comparable results.

Abstract Shochu is the most widely consumed spirit in Japan. In its manufacture is used koji, a solid fungus culture traditional of the Asian countries, but that makes the production process slow. Shochu can be produced from a variety of starchy sources, including sweet potato. About 7% of the world’s sweet potato production is wasted due to imperfections that make it unsuitable for consumption. However, this material can be used in ethanol production. Considering the high productivity of sweet potato in Brazil, an opportunity to add value to this raw material is perceived. An alternative process for the production of sweet potato distillate similar to shochu was proposed. Koji was replaced by a mixture of alpha-amylase and glucoamylase. Process time was reduced from 14 to only 1 day. Composition analyses were performed by HPLC and GC. The experimental yield of alcoholic fermentation using pectinase enzyme reached 67.31-73.65%, but methanol was above the limits of the legislation. Without the addition of pectinase, no methanol was formed. However, there was a decrease in yield (51.65-54.75%), due to the incomplete disintegration of sweet potatoes. The distillate produced and the commercial shochu presented the same absorption bands in FTIR analysis, identifying the similarity between them.

This study evaluated the feasibility of using vinasse as a nutrient source for microalgae cultivation. The Scenedesmus sp was grown in a medium supplemented with vinasse and process variables were optimized using a factorial design and a Central Composite Design (CCD). The factorial design results showed that it was possible to cultivate microalgae at concentrations of up to 40% of vinasse in the culture medium. The CCD results showed that the light intensity and vinasse concentration influenced the amount of biomass produced.

This study aimed at evaluating the best conditions for lipid accumulation in the marine microalga Nannochloropsis oculata in an airlift photobioreactor. Experiments were carried out following a central composite design with the following variables: temperature (19 to 29°C), sodium nitrate concentration (NaNO3) in the culture medium (f/2) (25 to 125 mg.L-1) and incident light intensity (49 to 140 µE.m-2s-1). The maximum lipid production was 132.4 mg.L-1 under the following conditions: 27°C, NaNO3 concentration 105 mg.L-1 and 122 µE.m-2.s-1, which was 30% of dry weight of the biomass.

(artigo convidado): Nos reatores de polimerização em fase gasosa, o controle de temperatura em uma estreita faixa de temperatura é importantíssimo para assegurar que a temperatura na zona de reação seja mantida acima do ponto de orvalho dos reagentes, assim como abaixo do ponto de fusão do polímero. Outro ponto importante é que se a temperatura estiver em malha aberta, estes reatores estão propensos à instabilidade e ao surgimento de ciclos limites, entretanto podem ser facilmente estabilizados com um controlador de temperatura apropriado. Neste trabalho é realizado um estudo detalhado do comportamento dinâmico de um reator industrial de polimerização em leito fluidizado, com a localização de pontos de bifurcação e estabilização do sistema com controlador PID projetado via otimização no domínio da freqüência.

(invited paper): In gas-phase ethylene polymerization reactors, tight temperature control is of utmost importance to ensure that the temperature in the reaction zone is kept above the dew point of reactants, yet below the melt point of the polymer. Another important point is that if the temperature was under open-loop conditions, these reactors are prone to instability and limit cycles, however can be easily stabilized with an appropriate temperature controller. In this work, a detailed study of the dynamic behavior of an industrial fluidized-bed polymerization reactor is carried out, with the location of bifurcation points and system stabilization by PID controller designed via optimization in the frequency domain.

O principal objetivo deste trabalho é a busca de uma solução mais eficiente e ambientalmente correta para a indústria do curtimento do couro (curtumes). Os curtumes são indústrias altamente consumidoras de águas e enfrentam sérios problemas com a geração de efluentes. Neste artigo, avaliaram-se alternativas de reuso da água de processo, as quais foram obtidas através da resolução de um problema de programação não-linear, visando minimizar o consumo de água em curtumes, mantendo a qualidade do produto final. Os resultados alcançados foram muito promissores e apontam para um potencial significativo de redução no consumo de água. Baseado no simples reuso de correntes, o consumo de água já pode ser reduzido significativamente, em torno de 70%. A solução obtida, além de reduzir o consumo de água, diminui significativamente o consumo de reagentes químicos e consequentemente a carga de poluentes a serem tratados posteriormente.

The aim of this work was to look for an efficient and environmentally safe solution for the leather tanning industry through a problem of non-linear programming. The results were promising and showed a significant potential of wastewater reduction. Reuse of internal streams reduced around 70% wastewater. The solutions obtained could reduce significantly the amount of chemicals and consequently the amount of waste to be treated.