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Recycling waste products of food industry become more and more important: one side because of the environmental matter the other side because of the economic reasons. The most preferred basic material for second generation biofuels is the waste products, food industrial waste products such as sugar chip, straw or bagasse. The cost of the process depends on the cost of the hydrolysis of cellulose/lignocelluloses i.e. the cost of the enzymes. These enzymes are very expensive that’s why it’s so important to find a good enzyme recovery method. In our research programme the membrane separation was used for enzyme recovery. Different ultra-filtration membranes such as a polyether-sulfone membrane with a cut-off value of 5 kDa, (PES5) and thin-film membrane with a cut-off value of 4 kDa (TF4) was used for separation the hydrolyzatethe aim of our work was to determine the optimal conditions for the enzymes separation, the value of the fluxes and the resistances values and the investigate the effect of the ultrasound on the membrane separation. We found that the fluxes are enhanced and the fouling resistance is decreased due to the ultrasound application and we also found that the gel layer resistance is increased during the processing. [ABSTRACT FROM AUTHOR]

For increasing cellulose accessibility to the enzymatic attack, the pretreatment is a necessary step to alter some structural characteristics of cellulosic materials. Microwave pre-treatment of sugar beet processing waste were investigated and compared to conventional heating in glucose yield and ethanol production by Simultaneous Saccharification and Fermentation (SSF) and conventional process. The results shows that conventional heating during 8 min has better glucose yield than microwave heating at 500 W during 5 min, respectively 66.03% (g glucose/g raw material) and 53.15% at pH 12. Results show also that microwave and conventional heating combined with NaOH solution has better effect cellulose degradation than combined with HCl. Parameters such as microwave intensity and irradiation time have a significant effect on cellulose structure and in this way increase glucose yield. Furthermore results show that higher microwave power with shorter pretreatment time and the lower microwave power with longer pretreatment time had almost the same effect on glucose yield and also in ethanol production. The highest ethanol yield was obtained with microwave/alkali pretreatment at 250 W during 10 min (24.04% g ethanol/g raw material), and do not differ with microwave/alkali 500 W during 5 min (21.94%). These yields are higher than those obtained with conventional heating, 14.00% for SSF. [ABSTRACT FROM AUTHOR]

The second generation bioethanol production has been a focus area of research and development activities worldwide. Bio-wastes generated in the agriculture and food industry can be considered a low priced and reproducible feedstock for biofuel technologies. Enhancing of the efficiency of enzymatic saccharification of lignocellulosic materials is a key issue to make the bioethanol fermentation more cost effective and increase the overall capacity of the process. Microwave (MW) pre-treatment is a novel technology to increase the sugar yield and ethanol production due to the accelerated cellulose hydrolysis. In our work, the effects of MW irradiation with different intensities and combination of them with acid and alkaline pre-treatments were investigated on the efficiency of saccharification of sorghum bagasse and black currant press residues. Our results show, that the MW pre-treatments could significantly increase the amount of hydrolyzed sugar from cellulose and the rate of decomposition was also accelerated. The highest degree of saccharification was observed after combined alkaline-microwave pre-treatment for both the sorghum bagasse and berry press residue, but the positive effect of MW irradiation on cellulose hydrolysis was limited using high intensity irradiation with longer exposure time. [ABSTRACT FROM AUTHOR]