Performance comparison of ethanol and butanol production in a continuous and closed-circulating fermentation system with membrane bioreactor.

Since both ethanol and butanol fermentations are urgently developed processes with the biofuel-demand increasing, performance comparison of aerobic ethanol fermentation and anerobic butanol fermentation in a continuous and closed-circulating fermentation (CCCF) system was necessary to achieve their fermentation characteristics and further optimize the fermentation process. Fermentation and pervaporation parameters including the average cell concentration, glucose consumption rate, cumulated production concentration, product flux, and separation factor of ethanol fermentation were 11.45 g/L, 3.70 g/L/h, 655.83 g/L, 378.5 g/m2/h, and 4.83, respectively, the corresponding parameters of butanol fermentation were 2.19 g/L, 0.61 g/L/h, 28.03 g/L, 58.56 g/m2/h, and 10.62, respectively. Profiles of fermentation and pervaporation parameters indicated that the intensity and efficiency of ethanol fermentation was higher than butanol fermentation, but the stability of butanol fermentation was superior to ethanol fermentation. Although the two fermentation processes had different features, the performance indicated the application prospect of both ethanol and butanol production by the CCCF system.

Controllable preparation of monodisperse alginate microcapsules with oil cores.

Here we report a novel strategy for controllable preparation monodisperse alginate microcapsules with oil cores, where the thickness of the alginate shells, as well as the number and diversity of the oil cores can be tailored precisely. Monodisperse oil-in-water-in-oil (O/W/O) emulsions are generated in a microfluidic device as templates, which contain alginate molecules and a water-soluble calcium complex in the middle aqueous phase. Alginate microcapsules are produced by gelling O/W/O emulsions in oil solution with acetic acid, where the pH decreasing will trigger the calcium ions being released from calcium complex and cross-linking with alginate molecules. Increasing the alginate molecule concentration in emulsion templates affects little on the thickness of the microcapsules but improves their stability in DI water. The strength of alginate microcapsules can be reinforced by post cross-linking in calcium chloride, polyetherimide, or chitosan solution. Typical payloads, such as thyme essential oil, lavender essential oil and W/O emulsions are encapsulated in alginate microcapsules successfully. Furthermore, tailoring the thickness of the alginate shells, as well as the number and the diversity of the oil cores precisely by manipulation the emulsion templates with microfluidics is also demonstrated. The proposed method shows excellent controllability in designing alginate microcapsules with oil cores.

Enhancing enzymatic hydrolysis yield of sweet sorghum straw polysaccharides by heavy ion beams irradiation pretreatment.

A deeper understanding of the pretreatment process of lignocellulosic biomass could enhance the production efficiency of biofuels. Sweet sorghum straws (SSS) were subjected to heavy ion beams irradiation (HIBI) pretreatment and then hydrolyzed with 2.4 FPU of cellulase. Notably, the pretreatment has been proved to increase enzymatic digestibility of SSS. The reducing sugar yield and hydrolysis yield of SSS pretreated by 600 Gray (Gy) of HIBI reached to 7.23 mg/mL and 34.43% for 36 h, respectively, which was significantly higher than that of the untreated SSS (4.93 mg/mL of reducing sugar and 23.47% of hydrolysis yield). Additionally, the analysis of pretreated SSS showed that the destruction of amorphous region and surface ultrastructure as well as the transformation of polymorphs (Iα →Iß) of cellulose I were major effects on SSS by HIBI pretreatment. The results demonstrated that HIBI could be chosen as an effective physical pretreatment process for enhancing enzymatic hydrolysis yield of lignocellulosic biomass.

Continuous acetone-butanol-ethanol (ABE) fermentation and gas production under slight pressure in a membrane bioreactor.

Two rounds of acetone-butanol-ethanol (ABE) fermentation under slight pressure were carried out in the continuous and closed-circulating fermentation (CCCF) system. Spores of the clostridium were observed and counted, with the maximum number of 2.1 × 10(8) and 2.3 × 10(8)ml(-1) separately. The fermentation profiles were comparable with that at atmospheric pressure, showing an average butanol productivity of 0.14 and 0.13 g L(-1)h(-1). Moreover, the average gas productivities of 0.28 and 0.27 L L(-1)h(-1) were obtained in two rounds of CCCF, and the cumulative gas production of 52.64 and 25.92 L L(-1) were achieved, with the hydrogen volume fraction of 41.43% and 38.08% respectively. The results suggested that slight pressures have no obvious effect on fermentation performance, and also indicated the significance and feasibility of gas recovery in the continuous ABE fermentation process.