Real Fermentation Broth Research Articles

Recovery of carboxylic acids from actual effluent by using sequential cationic-anionic adsorption steps at semi pilot scale

This work presents for the first time an exhaustive experimental assessment at semi-pilot scale for the sequential use of cationic-anionic adsorption columns for recovering carboxylic acids (CAs) from a real fermentation broth. The consecutive steps were dedicated to i) remove cations limiting the CAs interaction with the functional group of the anionic resin, and ii) adsorb CAs onto the anionic resin, respectively. The experimental broth was obtained from anaerobic co-fermentation of urban biowaste (UBW-broth). Breakthrough (BT) tests were firstly performed with the cationic column containing the strong-acid resin Lewatit® S2568H. This allowed both to assess the single process and to prepare 60 L of decationised UBW-broth to be used in the BT-tests with the anionic column (containing the weak-basic resin Lewatit® A365). Both columns were assessed (at 25°C) under packed and expanded bed modes, by feeding at different rates the actual UBW-broth or synthetic solutions. Main study innovative outputs were: 1) 100 % of the CAs occurring in UBW-broth were recovered with the proposed system; 2) best performances were obtained under expanded bed mode of operation, allowing to use 100 % of the installed capacity; 3) the affinity of other organic matter else than CAs resulted weaker than Na+/NH4+ and CAs/PO4x-/Cl- in both cationic and anionic columns, respectively (i.e. low adsorption performances generally reported are due to inorganic cations/anions presence); 4) a very preliminary economic analysis carried out on the basis of the obtained data indicates overall costs ranging 0.58–1.49 EUR/kg of CAs (depending on the process configuration).

Recovery of acetoin from Bacillus subtilis fermentation broth by supercritical CO2 extraction

AbstractComponent enrichment from fermentation broths by solvent extraction using supercritical carbon dioxide (sCO2) has been demonstrated in the literature. This work investigates for the first time the feasibility of the enrichment of an acetoin fraction from a real fermentation broth at a pilot plant scale using sCO2. A 4-m-tall, 28-mm-diameter, counter-current column packed with pall rings was used. The ranges of process pressure and temperature investigated were 100 to 300 bar, and 37 to 80 °C respectively. The optimum recovery of acetoin was 77.8%, with little difference between the simulated and actual broths. A modest two-fold concentration of acetoin was obtained in the extract. The results show that where a modest enrichment of the targeted product makes a significant difference in subsequent separation processes, and where the purity of the product, particularly from harmful solvents, is important, sCO2 fluid separation is a credible option for the enrichment of such products of fermentation.

Separation and purification of nylon 54 salts from fermentation broth by an integrated process involving microfiltration, ultrafiltration, and ion exchange.

Nylon 54 is a novel, biodegradable polyamide with excellent thermal resistance and water absorption properties. It can be polymerized using bio-based cadaverine and succinic acid as monomers. Traditional separation methods isolate individual monomers from the fermentation broth through acidification or alkalization, resulting in significant amounts of waste salts; however, synchronous separation of dibasic acids and diamines has not been reported. This study investigated an integrated process for the separation and extraction of nylon 54 salts from a co-fermentation broth without acidification or alkalization. We meticulously optimized the operational parameters of the integrated process to achieve maximum separation efficiency. Following microfiltration, ultrafiltration, and decolorization, the bacterial eliminating rate was ≥99.83%, and the protein concentration was ≤40mg/L. The absorbance of the decolorized solution was ≤0.021 at 430nm, and the recovery rate of nylon 54 salt reached 97%. Then, the pretreated solution was passed through sequential chromatographic columns, which effectively removed organic acid by-products (such as acetic acid and lactic acid), SO4 2-, and NH4 + from the fermentation broth, resulting in a cadaverine yield of 98.01% and a succinic acid yield of 89.35%. Finally, by concentrating and crystallizing the eluent, the simulated fermentation broth yielded nylon 54 salt with a purity of 99.16% and a recovery rate of 58%, and the real fermentation broth yielded nylon 54 salt with a purity of 98.10% and a recovery rate of 56.21%. This integrated process offers a sustainable and environmentally friendly pathway for the complete biosynthesis of nylon 54 salt and has the potential to be extended to the preparation of other nylon salts.

Stability of Filled PDMS Pervaporation Membranes in Bio-Ethanol Recovery from a Real Fermentation Broth.

Mixed matrix membranes (MMMs) have shown great potential in pervaporation (PV). As for many novel membrane materials however, lab-scale testing often involves synthetic feed solutions composed of mixed pure components, overlooking the possibly complex interactions and effects caused by the numerous other components in a real PV feed. This work studies the performance of MMMs with two different types of fillers, a core-shell material consisting of ZIF-8 coated on mesoporous silica and a hollow sphere of silicalite-1, in the PV of a real fermented wheat/hay straw hydrolysate broth for the production of bio-ethanol. All membranes, including a reference unfilled PDMS, show a declining permeability over time. Interestingly, the unfilled PDMS membrane maintains a stable separation factor, whereas the filled PDMS membranes rapidly lose selectivity to levels below that of the reference PDMS membrane. A membrane autopsy using XRD and SEM-EDX revealed an almost complete degradation of the crystalline ZIF-8 in the MMMs. Reference experiments with ZIF-8 nanoparticles in the fermentation broth demonstrated the influence of the broth on the ZIF-8 particles. However, the observed effects from the membrane autopsy could not exactly be replicated, likely due to distinct differences in conditions between the in-situ pervaporation process and the ex-situ reference experiments. These findings raise significant questions regarding the potential applicability of MOF-filled MMMs in real-feed pervaporation processes and, potentially, in harsh condition membrane separations in general. This study clearly confirms the importance of testing membranes in realistic conditions.

Enhanced, continuous, liquid-liquid extraction and in-situ separation of volatile fatty acids from fermentation broth

In 2018 alone, the US landfilled 35.3 million tons of food waste, about 24% of the total landfilled mass. In addition to the negative impacts landfills have demonstrated on the environment and human health, some states have begun to outlaw or dissuade the disposal of food waste and sewage sludge into landfills altogether. An urgent need has thus been created for the development of digestion processes like anaerobic digestion (AD) and arrested methanogenesis (AM) to convert food waste into valuable chemical products. Unfortunately, the buildup of volatile fatty acids (VFAs) during these processes eventually halts the reaction, and energy efficient methodologies for VFA removal are critical for the operation of fermenters. Additionally, VFAs themselves can serve as valuable chemical precursors, and recently AD processes have been modified to increase VFA production during fermentation. However, even with significant research over the past three decades, the separation of VFAs from the fermenter broth has remained expensive. Moreover, the separation of these VFAs from the fermenter broth may cost up to 50% of the entire process budget, hindering the widespread commercial adoption of AD and AM. In this work, we present a novel liquid–liquid extraction process termed CLEANS (Continuous Liquid-liquid Extraction And iN-situ Separation) as a highly efficient method for continuously separating VFAs from a real fermentation broth solely under gravity. Our optimized process (using an aqueous broth feed pH of 2.5, tri-n-octylamine as an extractant, and a 10:1 ratio of aqueous broth to organic extractant), achieved a VFA distribution constant KD = 44.5 ± 7.9, a single-pass recovery = 81.3 ± 2.5%, and an extraction factor = 8.1 ± 0.3. These KD values are over an order of magnitude higher than what has been previously reported for comparable processes. A high aqueous-to-organic flowrate ratio, enabled for the first time by CLEANS, was found to be particularly crucial for achieving optimal extraction. Our separation process demonstrates excellent reproducibility and potential for scalability. The economic and environmental implications of this work are briefly discussed.

Fouling of Polyalkylmethylsiloxane Composite Membranes during Pervaporation Separation of ABE-Fermentation Mixtures

Production of bio-alcohols is one of the approaches used in the development of alternative energy. Pervaporation is a promising option for the separation of bio-alcohols from the fermentation mixture. A serious problem in the process of continuous extraction of biobutanol from the fermentation broth is the contamination of the membrane, which leads to a decrease in its permeability over time. In this work, the transport properties of composite membranes based on polyheptylmethylsiloxane (PHeptMS), polydecylmethylsiloxane (PDecMS), and a commercial membrane MDK-3 were studied during separation of a real ABE-fermentation broth in vacuum pervaporation mode. The study was performed before and after continuous contact of the membranes with the fermentation broth for one month. Visually and by scanning electron spectroscopy, the presence of membrane surface residue and its effect on the wettability of the membrane selective layer by the components of the ABE broth were determined. The sediment composition was evaluated by energy dispersive analysis and infrared spectroscopy. According to the pervaporation separation of the ABE-broth using PHeptMS, PDecMS, and MDK-3 membranes, the butanol flux was 0.029, 0.012, and 0.054 kg/(m2·h), respectively. The butanol-water partition factor was 41, 22, and 13 for PHeptMS, PDecMS, and MDK-3, respectively. After one month of incubation of the membranes in ABE-fermentation broth during the separation of the model mixture, a decrease of 10 and 5% in permeate flux and separation factor, respectively, was observed for all membranes. Temperature dependences (30–60 °C) of permeate flux, permeability, and selectivity were obtained for the membranes after clogging. The most promising in terms of minimal negative changes as a result of fouling was demonstrated by the PHeptMS membrane. For it, the clogging dynamics during separation of the real fermentation broth for 216 h were investigated. Two characteristic steps of decrease in transport and separation properties were observed, after 28 and 150 h of the experiment. After 216 h of experiment, a 1.28-fold decrease in total flux through the membrane, a 9% decrease in butanol permeability, and a 10% decrease in n-butanol selectivity were found for PHeptMS.

Liquid–Liquid Extraction of Volatile Fatty Acids from Anaerobic Acidification Broth Using Ionic Liquids and Cosolvent

Promoting efficiency of liquid–liquid extraction at a high pH is a main challenge for the recovery of volatile fatty acids (VFAs) from organic wastes. In this study, the extraction efficiency of VFAs from artificial solution and acidification fermentation broth of kitchen wastes using ionic liquids (ILs) was assessed at high pH. The effect of ILs addition ratio in diluent, volumetric solvent to feed ratio (S/F) on extraction efficiency were investigated. The solvent consists of [P666,14][Cl] (IL101) and dodecane was found to be the promising solvent for VFA extraction at pH 6.0, especially for butyric acid. The IL-101 ratio in dodecane and S/F was significant factors for the liquid–liquid extraction of VFAs. In general, a higher IL-101 ratio and S/F can promote the extraction efficiency of single VFAs. As a result, the maximum extraction rate of acetic acid (38.4–49.9%) and butyric acid (66.0–92.1%) from different VFA concentration solutions was observed at 10% IL-101 in dodecane and S/F = 2/1. The solvent was also effective in different types of real fermentation broth of kitchen wastes. The maximum extraction rate and selectivity of butyric acid was 60.2%/70.5% in butyric acid type broth and 74.6%/62.7% in mixture acid type broth.

The Effect of Heat Sterilization on Key Filtration Performance Parameters of a Commercial Polymeric (PVDF) Hollow-Fiber Ultrafiltration Membrane.

Membrane processes can be integrated with fermentation for the selective separation of the products from the fermentation broth. Sterilization with saturated steam under pressure is the most widely used method; however, data concerning heat sterilization applicability to polymeric ultrafiltration (UF) membranes are scarcely available. In this study, the effect of the sterilization process on the filtration performance of a commercial polyvinylidene difluoride (PVDF) hollow fiber UF membrane was evaluated. Membrane modules were constructed and sterilized several times in an autoclave. Pure water flux tests were performed, to assess the effect of heat sterilization on the membrane’s pure water permeance. Dextran rejection tests were performed for the characterization of membrane typical pore size and its fouling propensity. Filtration performance was also assessed by conducting filtration tests with real fermentation broth. After repeated sterilization cycles, pure water permeance remained quite constant, varying between approx. 830 and 990 L·m−2·h−1·bar−1, while the molecular weight cut-off (MWCO) was estimated to be in the range of 31.5–98.0 kDa. Regarding fouling behavior, the trans-membrane pressure increase rate was stable and quite low (between 0.5 and 7.0 mbar/min). The results suggest that commercial PVDF UF membranes are a viable alternative to high-cost ceramic UF membranes for fermentation processes that require heat sterilization.

Butanol recovery from synthetic fermentation broth by vacuum distillation in a rotating packed bed

The present study was performed to investigate feasibility of butanol recuperation from a synthetic fermentation broth via vacuum distillation in a rotating packed bed (RPB). Unlike in stationary columns, the packing element rotates generating a centrifugal field which exceeds gravity by orders of magnitude. Thereby, the RPB improves the gas–liquid mass transfer by factors of 10 up to 1000, resulting in more efficient compounds separation. The process was performed under reduced pressure to allow temperatures getting closer to the typical fermentation temperature, which is usually between 35 and 37 °C. Therefore, the butanol recuperation can be carried out in-line without bacteria deactivation.The complex mixture used in this study was based on a real fermentation broth obtained during fermentation of cellulosic fraction of lignocellulosic biomass by butanol-tolerant mixed culture. Consequently, the composition of the synthetic fermentation broth as liquid feed stream was as following (g/L): 20 of butanol, 7 of ethanol, 2.5 of acetic acid, 3 of propionic acid, 5.5 of valeric acid, 2.0 of caproic acid, and 3.5 of furfural. Experiments under total reflux and stripping experiments using 5% of steam relative to the fermentation broth feed were performed. In the first case, butanol recuperation in the light phase of the top product reached concentration of 521.6 g/L. For stripping experiments, butanol concentration achieved the concentration at the level of 126.9 g/L in the top product. Ethanol and furfural were also recuperated at high concentrations at 39 and 13 g/L, respectively during stripping experiments. The experiments demonstrated that vacuum distillation in an RPB allows not only for separation of butanol from complex mixture but also for ethanol and furfural recuperation. Nevertheless, a further purification step is needed to achieve a pure product which can be used as an alternative fuel or feedstock substitute for the fossil components.

Separation of succinic acid from fermentation broth: Dielectric exclusion, Donnan effect and diffusion as the most influential mass transfer mechanisms

Nanofiltration can be used to separate succinic acid (SA) from other organic acids in a fermentation broth. However, commercial nanofiltration membranes can be insufficiently selective since some produced organic acids have similar molecular weights. SA production from biomass fermentation entails separation of succinic acid from the other concomitantly produced organic acids such as acetic acid, formic acid, pyruvic acid etc. In this study, five commercial nanofiltration membranes were tested for SA rejection and selectivity under dead-end and crossflow modes of SA recovery from selected synthetic solutions and a real fermentation broth. SA rejections up to 94.1 ± 1.5% and 95.5 ± 3.5% were observed for the synthetic broth and the fermentation broth, respectively. The SA fractions obtained in the retentate were nearly 70% and 60% for synthetic and fermentation broth, respectively. The highest rejections and SA fraction values were achieved with DK and NF270 membranes, which also showed the highest permeate flux. Model evaluation using the Donnan-steric pore model with dielectric exclusion (DSPM-DE) showed that 99% of the SA rejection occurs at the membrane interface and not inside the membrane. Based on the modelling, the most important mechanism affecting separation was dielectric exclusion at both sides of the membrane surfaces. Moreover, identified sensitive model parameters, i.e. pore dielectric constant (εpore), charge density (Xd) and pore radius (rp), were estimated through model fitting and were found to be highly correlated with significant variations. Finally, for the first time, a calibrated model with synthetic broth was successfully used to predict organic acids rejection for a real fermentation broth (with 12% and 3% prediction error for succinate rejection by NF270 and DK, respectively). Such prediction was achieved only by measuring organic acid concentrations in the fermentation broth and using the three sensitive parameters. Furthermore, the potential contribution of different transport mechanisms of SA was quantified for the first time.

Integrated ultrasound-mediated sugaring-out extraction of erythromycin from fermentation broth

• UMSO extraction reduced the extraction time (by 1/10th). • UMSO extraction reduced one step in downstream processing. • Antimicrobial activity and structure of erythromycin was unaltered. • Cell morphology was intact after UMSO extraction of erythromycin. This work investigates ultrasound-mediated sugaring-out extraction (UMSOE) of erythromycin from real fermentation broth. Various process conditions of the UMSOE system (time, pulse mode, probe position, temperature, acetonitrile (ACN)/water ratio, and glucose concentration) were evaluated for a model system (consisting of erythromycin) and optimized. Under the optimized process conditions (extraction time 6 min; pulse mode 20 s ON and 40 s OFF; probe position, interphase; temperature 4 °C; ACN/water ratio 1 and glucose 160 g/L), the maximum extraction efficiency of 91.6% w/w was attained. UMSOE of erythromycin from real fermentation broth resulted in 87 ± 1.88% extraction of erythromycin which was comparable with the model system and earlier studies. It is to be noted here that the time required for UMSOE is just 1/10th of sugaring-out extraction without ultrasound (control). It was carried without removing the cells, a practice followed at the industrial level and earlier studies. Further, the effect of UMSOE on antimicrobial activity and structure of erythromycin and morphology of Saccharopolyspora erythraea was also studied. The antimicrobial activity and structure of the erythromycin separated using UMSOE were comparable with the standard erythromycin. Also, the images of S. erythrea showed that the UMSOE had an insignificant effect on the morphology of the cells and the release of intracellular material. Thus, it can be concluded that UMSOE speeded up the extraction process (by reducing time and a cell removal step) and maintained the erythromycin activity intact. The physical and chemical effects of ultrasound helped intensify the process on a multifold basis.

Simultaneous solid-liquid separation and primary purification of clavulanic acid from fermentation broth of Streptomyces clavuligerus using salting-out extraction system.

Clavulanic acid (CA) is usually used together with other β‐lactam antibiotics as combination drugs to inhibit bacterial β‐lactamases, which is mainly produced from the fermentation of microorganism such as Streptomyces clavuligerus. Recently, it is still a challenge for downstream processing of low concentration and unstable CA from fermentation broth with high solid content, high viscosity, and small cell size. In this study, an integrated process was developed for simultaneous solid–liquid separation and primary purification of CA from real fermentation broth of S. clavuligerus using salting‐out extraction system (SOES). First, different SOESs were investigated, and a suitable SOES composed of ethanol/phosphate was chosen and further optimized using the pretreated fermentation broth. Then, the optimal system composed of 20% ethanol/15% K2HPO4 and 10% KH2PO4 w/w was used to direct separation of CA from untreated fermentation broth. The result showed that the partition coefficient (K) and recovery yield (Y) of CA from untreated fermentation broth were 29.13 and 96.8%, respectively. Simultaneously, the removal rates of the cells and proteins were 99.8% and 63.3%, respectively. Compared with the traditional method of membrane filtration or liquid–liquid extraction system, this developed SOES showed the advantages of simple operation, shorter operation time, lower process cost and higher recovery yield of CA. These results demonstrated that the developed SOES could be used as an attractive alternative for the downstream processing of CA from real fermentation broth.

Implementation of forward osmosis to concentrate alpha-ketoglutaric acid from fermentation broth: Performance and fouling analysis

Forward osmosis (FO) was demonstrated as a promising method to concentrate alpha-ketoglutaric acid in fermentation broth. Using a model solution containing alpha-ketoglutaric acid, the impact of the initial pH value on water flux, reverse salt flux, and rejection of alpha-ketoglutaric acid were first elucidated. Results from this study show that water flux was not affected by feed solution pH. However, feed solution pH could influence alpha-ketoglutaric acid rejection and reverse salt flux. The highest alpha-ketoglutaric acid rejection of 99.7% and lowest reverse salt flux were observed at pH 5. Multi-component model and real fermentation broth were then used to validate FO application for concentrating alpha-ketoglutaric acid. Water recovery of 80% was achieved without severe membrane fouling. In addition, membrane fouling analysis show that the built-up fouling layer of impurities is flaky and of unstable nature, suggesting that membrane fouling could be reversible. Knowledge of the fouling layer formation can contribute to the development of an effective method of pretreatment of the fermentation broth and cleaning FO membranes in the future.

Lactic acid recovery from date pulp waste fermentation broth by ions exchange resins

The recovery of lactic acid (LA) from fermentation broth remains a challenge considering its purity and purification cost. The use of ion-exchange resins to recover lactic acid (LA) from the broth of date pulp waste fermented with indigenous bacteria was explored in this study. For this purpose, commercially available AmberliteIRI-67 and IR-120 resins were utilized to purify and recover LA from the broth. The effect of pH, initial concentration, and binding ability was optimized in the initial set of experiments. LA was extracted from the fermentation broth by a weak anion exchanger followed by a cation exchanger. The maximum adsorption capacity of LA (150 mg/g) was observed with weak anion resin at an initial pH 3. The pH showed a significant effect, and a pH value below the pKa of LA was found to be favorable for high adsorption capacity. In a fixed-bed column, 91% LA recovery with 94.6% optical purity was achieved from real fermentation broth. Both resins remained stable during the recovery of LA. Successful desorption and regeneration (98.2% recovery of LA) of the anion-exchange resin was achieved using 1 M HCl as an eluent. Compared to the Freundlich model, the Langmuir and Dubinin–Radushkevich isotherm model (R 2 = 0 .90-0.99) matched the experimental results fairly well. The results of this study showed that the ion exchange chromatography technique with weak anion and strong cation exchangers has the potential to be used for LA recovery from fermentation broth. • LA extracted from the fermentation broth by a weak anion followed by a cation exchanger. • The maximum adsorption of LA (150 mg/g) was observed with weak anion resin at an initial pH 3. • In a fixed-bed column, 91% LA recovery with 95% optical purity from the fermentation broth was achieved. • Successful desorption (98.2% LA) of the anion-exchange resin with 1 M HCl was achieved. • Langmuir and DR isotherm model (R 2 90-99) matched the experimental results fairly well.

One-Step and Low-Cost Designing of Two-Layered Active-Layer Superhydrophobic Silicalite-1/PDMS Membrane for Simultaneously Achieving Superior Bioethanol Pervaporation and Fouling/Biofouling Resistance.

Recently, the coupling of biofuel fermentation broths and pervaporation has been receiving increasing attention. Some challenges, such as the destructive effects of constituents of the real fermentation broth on the membrane performances, the lethal effects of the membrane surface chemical modifiers on the microorganisms, and being expensive, are against this concept. For the first time, a continuous study on the one-step and low-cost preparation of superhydrophobic membranes for bioethanol separation is made to address these challenges. In our previous work, spraying as a fast, scalable, and low-cost procedure was applied to fabricate the one-layered active-layer hydrophobic (OALH) silicalite-1/polydimethylsiloxane (PDMS) membrane on the low-cost mullite support. In this work, the spraying method was adopted to fabricate a two-layered active-layer superhydrophobic (TALS) silicalite-1/PDMS membrane, where the novel active layer consisted of two layers with different hydrophobicities and densities. Contact-angle measurements, surface charge determination, scanning electron microscopy, atomic force microscopy, and pervaporation separation using a 5 wt % ethanol solution were used to statically evaluate the fouling/biofouling resistance and pervaporation performances of OALH and TALS membranes in this study. The TALS membrane presented a better resistance and performance. For dynamic experiments, the Box-Behnken design was used to identify the effects of substrates, microorganisms, and nutrient contents as the leading indicators of fermentation broth on the TALS membrane performances for the long-term utilization. The maximum performances of 1.88 kg/m2·h, 32.34, and 59.04 kg/m2·h concerning the permeation flux, separation factor, and pervaporation separation index were obtained, respectively. The dynamic fouling/biofouling resistance of the TALS membrane was also characterized using energy-dispersive X-ray spectroscopy of all the tested membranes. The TALS membrane demonstrated the synergistic resistance of membrane fouling and biofouling. Eventually, the novel TALS membrane was found to have potential for biofuel recovery, especially bioethanol.

Investigation of Itaconic Acid Separation by Operating a Commercialized Electrodialysis Unit with Bipolar Membranes

Nowadays, the merging of membrane and fermentation technologies is receiving significant attention such as in the case of itaconic acid (IA) production, which is considered as a value-added chemical. Its biotechnological production is already industrially established; however, the improvements of its fermentative and recovery steps remain topics of significant interest due to sustainable development trends. With an adequate downstream process, the total price of IA production can be reduced. For the task of IA recovery, a contemporary electro-membrane separation processes, electrodialysis with bipolar membranes (EDBM), was proposed and employed in this work. In the experiments, the laboratory-scale, commercialized EDBM unit (P EDR-Z/4x) was operated to separate IA from various model solutions compromised of IA (5–33 g/L), glucose (varied in 15–33 g/L as a residual substrate during IA fermentation) and malic acid (varied in 0–1 g/L as a realistic by-product of IA fermentation) under different initial pH (2–5) and applied potential conditions (10–30 V). Unambiguously negative effects related to the glucose and malic acid as impurities were found neither on the IA recovery ratio nor on the current efficiency, falling into the ranges of 90–97% and 74.3–98.5%, respectively. The highest IA recovery ratios of 97% and 98.5% of current efficiency were obtained with the model fermentation solution containing 33 g/L IA, 33 g/L glucose at 20 V and an initial pH of 5. However, the selective separation of IA needs further investigations with a real fermentation broth, and the findings of this research may contribute to further studies in this field.

Membrane Distillation of Butanol from Aqueous Solution with Polytetrafluoroethylene Membrane

AbstractNowadays, butanol is considered as biofuel. In this work, separation of butanol from aqueous solution was carried out by vacuum membrane distillation with polytetrafluoroethylene membrane, using mechanical vapor compression on the downstream. Higher flow rates could promote membrane separation with higher total flux and higher separation factor, thus influencing butanol separation. Membrane fouling was observed which exerted a substantial effect on the membrane separation performance with a real fermentation broth. Compared to the traditional distillation process, this procedure is more cost‐effective due to ∼ 50 % reduced energy consumption.

The effect of fermentation broth composition on removal of carboxylic acids by reactive extraction with Cyanex 923

This paper presents results of liquid-liquid extraction of carboxylic acids, particularly succinic acid (Suc), from one-, two-and multi-component model solutions, and from a fermentation broth with 0.1 and 0.4 mol/L Cyanex 923 (solvating extractant, mixture of trialkylphosphine oxides). As the idea of the extraction is to concentrate Suc in the organic phase, thus, the optimum conditions of extraction are proposed, i.e. 0.4 mol/L Cyanex 923) at low volume of the organic phase (o/w = 1/2), to obtain high extraction efficiency (64%) and to enrich Suc in the organic phase (almost 8 g/L in relation to 6 g/L in the feed). The presence of polyols (propane-1,3-diol, glycerol) in Suc model solutions does not affect Suc extraction efficiency, while the presence of such carboxylic acids as lactic (Lac), acetic (Ac) or formic (For) results in a competition between Suc and other acids. Extraction efficiency of the acids from the real fermentation broth decreases in the following order: But ≫ For ≈ Ac > Lac, which is consistent with their increasing hydrophilicity. The total yield of the proposed extraction-stripping process amounts to 70% recovery of succinic acid. The results prove that the extraction with Cyanex 923 is effective for separation of carboxylic acids from polyols (propane-1,3-diol, glycerol).

Isopropanol, n‐butanol and ethanol recovery from IBE model solutions by salting‐out using potassium pyrophosphate

AbstractBACKGROUNDIsopropanol, n‐butanol and ethanol (IBE) could be used as a clean and renewable biofuel. However, the separation and purification of IBE requires more energy due to the low concentration of IBE in fermentation broth and the existence of azeotropes. Here, we investigate in detail the separation ability of IBE from two typical model solutions by salting‐out with potassium pyrophosphate (K4P2O7) as the salting‐out agent.RESULTSIncreasing the salt content could effectively increase the distribution coefficient and selectivity coefficient of IBE. The recovery of IBE was over 95 wt%, and the dehydration ratio could reach above 99.8 wt%. A higher total organic compound content could increase the recovery of IBE but could decrease the dehydration ratio. The logarithm of solubility of IBE in the aqueous phase or water content in the organic phase has a good linear relationship with the molality of K4P2O7.CONCLUSIONThis study demonstrated the ability of K4P2O7 to recover IBE from IBE model solutions during the separation process. The results showed that the salting‐out method has the potential to save energy in recovering IBE from a real fermentation broth. © 2019 Society of Chemical Industry

Poly(trimethylsilylpropyne) Membranes for Removal of Alcohol Fermentation Products by Thermopervaporation with a Porous Condenser

Dense membranes made of poly[1-(trimethylsilyl)-1-propyne] (PTMSP) have been studied in thermopervaporation (TPV) separation of a butanol–water binary mixture and a real acetone–butanol–ethanol (ABE) broth. When comparing PTMSP with commercially used membranes based on polydimethylsiloxane (PDMS) in the TPV process, a significant advantage of PTMSP with respect to the butanol/water selectivity is shown. The value of the separation factor for the PTMSP membrane (114) with a thickness of 61 μm is more than ninefold higher than that of the most selective Pervap 4060 commercial membrane (Sulzer Chemtech, Switzerland). The permselectivity of PTMSP membranes with respect to the butanol/water components exceeds that of commercial membranes more than fivefold. The removal of acetone, butanol, and ethanol from real fermentation broths using PTMSP membranes in the TPV process with a porous condensation surface has been studied for the first time. It has been shown that the transport and separation characteristics of PTMSP membranes in the process of separation of real fermentation broths decline with time, while demonstrating high values of the butanol/water permselectivity (4.7).