No abstract

In this paper, an enclosed membrane-photobioreactor was designed to remove CO 2 using Chlorella vulgaris. The performances of four reactors, which included the presented novel bioreactor, a draft tube airlift photobioreactor, a bubble column and a membrane contactor, were compared. The effects of the gas flow rate, light intensity, quality of the inner light source, and the characteristics of membrane module on CO 2 fixation were investigated. The results showed that the rate of CO 2 fixation in the membrane-photobioreactor was 0.95-5.40 times higher than that in the other three conventional reactors under the optimal operating conditions IntroductionThe CO 2 concentration of the environment is of great importance to worldwide health. The optimal CO 2 concentration for human beings is ca. 0.04 %. Higher concentration may cause headaches, tinnitus and elevated blood pressure. Therefore, the concentration range of CO 2 in isolated environments such as a space station or a submarine must normally be strictly controlled to be less than 0.5 %.Physicochemical absorbents are widely used for CO 2 removal at present. These materials, e.g., LiOH, are normally non-renewable, and thus, routine replenishment is required and significant extra space is necessary for their storage. Therefore, a reliable, effective and renewable air cleaning system is strongly desired. One approach to make such a system is to utilize microalgae, a photoautotropic microorganism, which has been proven to be a natural source of high-value compounds for the pharmaceutical and food industries [1][2][3]. CO 2 is removed by microalgae through photosynthesis, while oxygen is produced simultaneously, and one is also able to supply food via the choice of microalgae species within edible biomass [4].The process of CO 2 fixation in a microalgal cultivation system, commonly a photobioreactor, is complicated by the effects of cellular metabolism, irradiance distribution and gas-liquid mass transfer. Chlorella vulgaris (C. vulgaris), one of the edible green algae, has been considered to be very suitable for CO 2 biological fixation, since it has a good photosynthetic capacity, high reproduction rate and is easy to utilize in engineering systems [5][6][7]. However, due to the severe cellular self-shading effects, especially with dense culturing and strong external irradiance, a large dark zone in the center and a small highly illuminated zone near the surface coexist in a photobioreactor, neither of which is appropriate for the cell's growth [8]. Thus, a lot of attention is being given to light availability for the design of a photoreactor with the aim of increasing the mass or metabolite productivity [9][10][11][12]. However, the effect of gas-liquid mass transfer is usually disregarded since CO 2 removal is not the main purpose in most studies of microalgae cultivation.Based on previous research by the current authors [13][14][15], a membrane-photobioreactor with a hollow fiber membrane module integrated inside, was designed to remove CO 2 with C. vulgaris in...

Tang D.-S., Tian Y.-J., He Y.-Z., Li L., Hu S.-Q., Li B. (2010): Optimisation of ultrasonic-assisted protein extraction from brewer's spent grain. Czech J. Food Sci., 28: 9-17, Response surface methodology was employed to optimise the ultrasonic-assisted extraction of protein from brewer's spent grain. Three variables, namely the extraction time (min), ultrasonic power (W/100 ml of extractant), and solid-liquid ratio (g/100 ml) were investigated. Optimal conditions were determined and tri-dimensional response surfaces were plotted using mathematical models. The ANOVA analysis indicated that all the quantities determined, i.e. the extraction time, ultrasonic power, and solid-liquid ratio, had significant positive linear and negative quadratic effects on the protein yield. Optimum conditions for the extraction of protein were found to be: the extraction time of 81.4 min, ultrasonic power of 88.2 W/100 ml of extractant, and solid-liquid ratio of 2.0 g/100 ml. The optimal predicted protein yield obtained was 104.2 mg/g BSG while the experimental yield of protein was in agreement with the predicted value.

Laser-induced fluorescence was used to evaluate the classification and quality of Chinese oolong teas and jasmine teas. The fluorescence of four different types of Chinese oolong teas-Guangdong oolong, North Fujian oolong, South Fujian oolong, and Taiwan oolong was recorded and singular value decomposition was used to describe the autofluoresence of the tea samples. Linear discriminant analysis was used to train a predictive chemometric model and a leave-one-out methodology was used to classify the types and evaluate the quality of the tea samples. The predicted classification of the oolong teas and the grade of the jasmine teas were estimated using this method. The agreement between the grades evaluated by the tea experts and by the chemometric model shows the potential of this technique to be used for practical assessment of tea grades.