Downstream separation and purification of bio-based alpha-ketoglutaric acid from post-fermentation broth using a multi-stage membrane process

In this study, a multi-stage membrane process, assisted by vacuum evaporation and crystallization, for recovery of bio-based alpha-ketoglutaric acid from the actual post-fermentation broth was designed and investigated. In the first part of this study, pre-treatment of crude fermentation broth (centrifugation-ultrafiltration-nanofiltration) was carried out to remove biomass, proteins, sugars, part of inorganic ions and color compounds. The commercial ceramic UF membrane (15 kDa) and nanofiltration ceramic membrane (200 Da or 450 Da) were applied. Electrodialysis with a bipolar membrane was proposed for separation of ionic compounds and simultaneous electro-acidification to the acid form. During bipolar membrane electrodialysis carried out under acidic conditions, it was possible to remove close to 90 % of alpha-ketoglutaric acid. Moreover, the migration of other acids present in the fermentation broth (lactic and acetic) was significantly limited. The calculated specific energy consumption was low and equal to 0.6 kW h/kg. The final purification using crystallization assisted vacuum evaporation allowed obtaining alpha-ketoglutaric acid in solid form. Analysis of the final product showed that the proposed method of alpha-ketoglutaric acid recovery gives the acid of high purity equal to 94.8 %. Furthermore, the presented results have practical relevance and may in future be the basis for the development of separation technologies of alpha-ketoglutaric acid from the fermentation broth on industrial scale.     

The effect of electrodialytic treatment and Na2H2EDTA addition on methanogenic activity of copper-amended anaerobic granular sludge: treatment costs and energy consumption

The effect of electrodialytic treatment in terms of a current density, pH and Na₂H₂EDTA addition on the methanogenic activity of copper-amended anaerobic granular sludge taken from the UASB reactor from paper mill was evaluated. Moreover, the specific energy consumption and simplified operational and treatment costs were calculated. Addition of Na₂H₂EDTA (at pH 7.7) to copper-amended sludge resulted in the highest microbial activity (62 mg CH₄-COD g VSS⁻¹ day⁻¹) suggesting that Na₂H₂EDTA decreased the toxic effects of copper on the methanogenic activity of the anaerobic granular sludge. The highest methane production (159 %) was also observed upon Na₂H₂EDTA addition and simultaneous electricity application (pH 7.7). The energy consumption during the treatment was 560, 840, 1400 and 1680 kW h m⁻³ at current densities of 0.23, 0.34, 0.57 and 0.69 mA cm⁻², respectively. This corresponded to a treatment costs in terms of electricity expenditure from 39.2 to 117.6 € per cubic meter of sludge.     

Production of l-lactic acid by electrodialysis fermentation (EDF)

An efficient process for producing l-lactic acid using an, EDF method is described. The results showed that intermittent EDF with continuous medium feed was the best one among the experiment methods employed. Comparing with the conventional EDF, intermittent EDF (seven on–off) with continuous medium feed indicated that the maximum value of o.d.₆₆₀ was not increased, but productivity was 1.5 times higher. The yield increased by above 30% and glucose transport decreased to 1/10 (from 0.46 to 0.05).     

Enhancing bioethanol production from delactosed whey permeate by upstream desalination techniques

Industrial cheese whey processing comprises generally the isolation of proteins and lactose, but the economic use for the residual molasses, the so‐called delactosed whey permeate (DWP), is still to be improved. One possibility to maximize valorization and to minimize waste water treatment is the conversion of the remaining lactose in the DWP to ethanol by the yeast Kluyveromyces marxianus. This fermentation process depends strongly on the total ash content of the DWP, as high salt concentrations inhibit yeast metabolism. Here, three different approaches were tested to lower the DWP salt content: (i) simple dilution; (ii) nanofiltration; and (iii) electrodialysis. Lactose consumption, ethanol production and time‐dependent yields were compared between the three methods. A dilution of DWP to 60% v/v led to fermentation taking less than 80 h and yield above 7% AbV (alcohol by volume). After nanofiltration, 7.5% AbV was produced in about 80 h, and after electrodialysis, 11% AbV was produced in about 52 h. On the one hand the technical treatments (nanofiltration and electrodialysis) led to enhanced productivity in the fermentations, but, on the other hand, elaborate and extensive preprocessing is needed. Overall, ethanol production from DWP could be enhanced by prior partial desalination.     

电渗析法分离提纯N-乙酰-L-半胱氨酸研究

使用我校由辐射法制备的高性能离子交换膜ＨＦ—１及ＨＦ—２,采用电渗析技术对合成所得的Ｎ－乙酰－Ｌ－半胱氨酸进行了分离提纯,脱盐率＞１５％,损失率＜１５％,为工业化应用提供了依据。     

电渗析技术用于猪毛水解液脱酸的研究

利用上海华凯科技贸易公司制作的HF系列离子交换膜为隔膜的电渗析器对猪毛水解液进行电渗析脱酸,研究了脱酸过程中浓缩室、淡化室酸度变化及电流效率     

电渗析发酵法生产乳酸的研究

在乳酸发酵过程中,所生成的乳酸对进一步发酵有抑制作用。采用电渗析法从发酵液中及时地分离出产物乳酸,使乳酸的生产量提高到86.4g/L,是不控制pH值发酵时的4倍多。结果表明:电渗析法能有效地消除产物乳酸的抑制作用,提高了乳酸生产率,且简化了提取工艺。     

Rapid and efficient production of L-lactate from xylose using electrodialysis culture-associated product separation

L-Lactate was produced from xylose using electrodialysis culture (ED-C)-associated product separation. In a medium containing 50g xylose/l, the ED-C was completed in only 32h (i.e. less than half the time taken by the control culture, without electrodialysis). At 80g xylose/l, the control culture was unable to consume more than 50g xylose/l, whereas the ED-C showed increased xylose consumption and was completed by 45h. The maximum rate of lactate production in the ED-C was higher than that in the control culture. ED-C was also carried out (at 80g initial xylose/l) with a supply of fresh xylose-free medium. This ED-C was completed within 30h, which represents a reduction in fermentation time of 15h when compared to ED-C without addition of xylose-free medium. Thus, rapid production of L-lactate was achieved by using ED-C which supplied fresh xylose-free medium.     

复合氨基酸电渗析脱盐过程中的动态

本文利用电渗析技术对猪毛水解废液进行脱盐研究以获取很有应用价值的复合氨基酸。重点研究了各种氨基酸在脱盐过程中的变化行为。     

Seed culture affects the completion time of L-lactate fermentation using electrodialysis culture

Electrodialysis culture (ED-C) and control culture of Lactococcus lactis IO-1 were inoculated with 3 and 12 h seed cultures. Regardless of seed culture age, control cultures needed 30 h for the completion of L-lactate fermentation. By contrast, the fermentation times for ED-Cs inoculated with 3 and 12 h seed cultures were reduced by 38 and 27% when compared to those of control cultures. Seed culture age can be varied to reduce the fermentation time for ED-C.