Fluid dynamics in Sartobind membrane adsorber systems

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Eucalyptus Kraft Lignin as an Additive Strongly Enhances the Mechanical Resistance of Tree-Leaf Pellets

Pelleted biomass has a low, uniform moisture content and can be handled and stored cheaply and safely. Pellets can be made of industrial waste, food waste, agricultural residues, energy crops, and virgin lumber. Despite their many desirable attributes, they cannot compete with fossil fuel sources because the process of densifying the biomass and the price of the raw materials make pellet production costly. Leaves collected from street sweeping are generally discarded in landfills, but they can potentially be valorized as a biofuel if they are pelleted. However, the lignin content in leaves is not high enough to ensure the physical stability of the pellets, so they break easily during storage and transportation. In this study, the use of eucalyptus kraft lignin as an additive in tree-leaf pellet production was studied. Results showed that when 2% lignin is added the abrasion resistance can be increased to an acceptable value. Pellets with added lignin fulfilled all requirements of European standards for certification except for ash content. However, as the raw material has no cost, this method can add value or contribute to financing continued sweeping and is an example of a circular economy scenario

A Study of the Reinforcement Effect of MWCNTs onto Polyimide Flat Sheet Membranes

Polyimides rank among the most heat-resistant polymers and find application in a variety of fields, including transportation, electronics, and membrane technology. The aim of this work is to study the structural, thermal, mechanical, and gas permeation properties of polyimide based nanocomposite membranes in flat sheet configuration. For this purpose, numerous advanced techniques such as atomic force microscopy (AFM), SEM, TEM, TGA, FT-IR, tensile strength, elongation test, and gas permeability measurements were carried out. In particular, BTDA–TDI/MDI (P84) co-polyimide was used as the matrix of the studied membranes, whereas multi-wall carbon nanotubes were employed as filler material at concentrations of up to 5 wt.% All studied films were prepared by the dry-cast process resulting in non-porous films of about 30–50 μm of thickness. An optimum filler concentration of 2 wt.% was estimated. At this concentration, both thermal and mechanical properties of the prepared membranes were improved, and the highest gas permeability values were also obtained. Finally, gas permeability experiments were carried out at 25, 50, and 100 ◦C with seven different pure gases. The results revealed that the uniform carbon nanotubes dispersion lead to enhanced gas permeation properties

The effects of high shear rates on the average hydrodynamic diameter measured in biomimetic HIV Gag virus-like particle dispersions

HIV Gag virus-like particles (HIV Gag VLPs) are promising HIV vaccine candidates. In the literature, they are often described as shear-sensitive particles, and authors usually recommend the operation of tangential flow filtration (TFF) gently at shear rates below 4,000 s−1 to 6,000 s−1. This in turn poses a severe limitation to the performance of TFF-mediated concentration of VLPs, which would be substantially enhanced by working at higher shear rates. To our knowledge, studies examining the shear sensitivity of HIV Gag VLPs and providing detailed information and evidence for the fragility of these particles have not been conducted yet. Thus, we investigated the effect of high shear rates on the colloidal stability of mosaic VLPs (Mos-VLPs) as relevant examples for HIV Gag VLPs. For this purpose, Mos-VLPs were exposed to different shear rates ranging from 3,395 s−1 to 22, 365 s−1 for 2 h. The average hydrodynamic diameter (AHD) and the polydispersity index (PDI) of the associated particle size distribution were used as stability indicators and measured after the treatment and during storage through dynamic light scattering. At high shear rates, we observed an increase in both AHD and PDI during the storage of HIV Mos1.Gag VLPs (bVLP—without envelope proteins) and Mos1.Gag + Mos2S.Env VLPs (eVLP—with envelope proteins). eVLPs exhibited higher colloidal stability than bVLPs, and we discuss the potential stabilizing role of envelope proteins. We finally demonstrated that the dispersion medium also has a considerable impact on the stability of Mos-VLPs

New feedstocks for bioethanol production

In the last few decades raw material molasses, used in large scale fermentations in the production of bioethanol, citric acid, (baker´s) yeast and yeast extracts, has become more and more expensive. That is why agro-industrial wastes have become an interesting alternative. They are being produced in large volumes every day and represent a serious environmental problem considering its high organic content. The present contribution aims to demonstrate how waste products of wine production can be employed as substrate in bioethanol production. Cultivation of yeast and bioethanol production on molasses and grape pomace extract was studied in flasks in laboratory scale. This work should be regarded as an example of integrated sustainability which demonstrates how the waste from one industrial process is used as feedstock for another

Transformacija problematičnog vinskog otpada u vrijedan supstrat za proizvodnju pekarskog kvasca i čvrstog biogoriva: princip kružnog gospodarstva

Research background. Wine production, which is considered a major sector in food industry, often involves the use of a large amount of resources. Moreover, wine making generates a large amount of grape pomace, which is generally used for low-value applications such as fertiliser and animal feed. The aim of the present research is to explore the possibility of improving the overall sustainability of traditional winemaking. Experimental approach. A zero-waste process was developed. It includes the production of white wine and the substantial valorisation of grape pomace, which is converted into solid biofuel, tartaric acid and concentrated grape extract as feedstock for industrial baker’s yeast production. Results and conclusions. We estimate that a significant surplus of renewable energy of approx. 3 MJ/kg processed grapes can be obtained during this conversion. The suitability of grape extract as a potential substrate for industrial baker’s yeast production was evaluated and the feasibility of a partial replacement of molasses (up to 30 %) was demonstrated. Novelty and scientific contribution. We present a circular economy approach for the conversion of winery biowaste into high-value resources such as feedstock and solid biofuel.Pozadina istraživanja. Proizvodnja vina, koja se smatra važnim sektorom u prehrambenoj industriji, često uključuje korištenje velikih resursa. Osim toga, nakon proizvodnje vina zaostaju velike količine komine grožđa, koja se obično koristi za dobivanje proizvoda niske vrijednosti, poput gnojiva ili stočne hrane. Svrha je ovog znanstvenog rada bila istražiti mogućnost poboljšanja ukupne održivosti tradicionalnog postupka proizvodnje vina. Eksperimentalni pristup. U radu je razvijen postupak koji uključuje proizvodnju bijelog vina i značajnu valorizaciju komine grožđa, koja se pretvara u čvrsto biogorivo, vinsku kiselinu i koncentrirani ekstrakt grožđa kao sirovinu za industrijsku proizvodnju pekarskog kvasca. Rezultati i zaključci. Procjenjujemo da se ovom metodom može dobiti značajan višak obnovljive energije od otprilike 3 MJ/kg obrađenog grožđa tijekom postupka. Istražena je moguća uporaba ekstrakta grožđa kao potencijalne sirovine u industrijskoj proizvodnji pekarskog kvasca, te je dokazana mogućnost djelomične zamjene melase s ekstraktom grožđa (do 30 %). Novina i znanstveni doprinos. U radu predstavljamo princip kružnog gospodarstva pri pretvaranju biološkog vinskog otpada u visokovrijedne resurse, poput sirovina i čvrstog biogoriva

Visualization of the Two-Phase Flow Behavior Involved in Enhanced Dense Phase Carbon Dioxide Pasteurization by Means of High-Speed Imaging

This research explores the two-phase flow behavior involved in enhanced dense phase carbon dioxide inactivation of E. coli DH5α, which has been shown to possess a high microbial reduction efficiency of up to 3.7 ± 0.4 log. We present an experiment in which the liquid sample was pressurized with liquid carbon dioxide to 8.2 MPa and, after saturation, was forced to flow through a mini tube. An experimental setup was developed to visualize the flow patterns (plug, slug and churn flows) occurring in the mini tube by means of high-speed imaging. The values of the wall shear stress were estimated within the mini tube with the help of the gas slug velocities (8–9 m/s) and were compared with threshold shear stress values reported for the disruption of fresh E. coli cells. The results suggest that the preliminary pressurization phase may cause a substantial destabilization of the cell wall of E. coli DH5α

Bridging the Implementation Gap between Pomace Waste and Large-Scale Baker’s Yeast Production

The objectives set in the European Green Deal constitute the starting point of this review, which then focuses on the current implementation gap between agro-industrial wastes as resources for large-scale bioprocesses (e.g., baker’s yeast, bioethanol, citric acid, and amino acids). This review highlights the current lack of sustainability of the post-harvest processing of grapes and apples. In light of the European Green Deal, industrial biotechnology often lacks sustainability as well. We reviewed the recent progress reported in the literature to enhance the valorization of grape and apple pomace and the current failure to implement this research in technical processes. Nevertheless, selected recent papers show new perspectives to bridge this gap by establishing close collaborations between academic teams and industrial partners. As a final outcome, for the first time, we drew a circular flow diagram that connects agriculture post-harvest transformation with the industrial biotechnology and other industries through the substantial valorization of apple and grape pomace into renewable energy (solid biofuels) and sugar extracts as feedstock for large-scale bioprocesses (production of baker’s yeast industry, citric acid, bioethanol and amino acids). Finally, we discussed the requirements needed to achieve the successful bridging of the implementation gap between academic research and industrial innovation

A Hydrodynamic Approach to the Study of HIV Virus-Like Particle (VLP) Tangential Flow Filtration

Emerging as a promising pathway to HIV vaccines, Virus-Like Particles (VLPs) have drawn considerable attention in recent years. A challenge of working with HIV VLPs in biopharmaceutical processes is their low rigidity, and factors such as shear stress, osmotic pressure and pH variation have to be reduced during their production. In this context, the purification and concentration of VLPs are often achieved by means of Tangential Flow Filtration (TFF) involving ultrafiltration hollow fiber modules. Despite the urgent need for robust upscaling strategies and further process cost reduction, very little attention has been dedicated to the identification of the mechanisms limiting the performance of HIV VLP TFF processes. In this work, for the first time, a hydrodynamic approach based on particle friction was successfully developed as a methodology for both the optimization and the upscaling of HIV VLP TFF. Friction forces acting on near-membrane HIV VLPs are estimated, and the plausibility of the derived static coefficients of friction is discussed. The particle friction-based model seems to be very suitable for the fitting of experimental data related to HIV VLP TFF as well as for upscaling projections. According to our predictions, there is still considerable room for improvement of HIV VLP TFF, and operating this process at slightly higher flow velocities may dramatically enhance the efficiency of VLP purification and concentration. This work offers substantial guidance to membrane scientists during the design of upscaling strategies for HIV VLP TFF

Enhancing DPCD in Liquid Products by Mechanical Inactivation Effects: Assessment of Feasibility

The enhancement of standard dense phase carbon dioxide (DPCD) pasteurization by additional mechanical effects was assessed in this work. These effects were induced during pasteurization by the sudden depressurization in a narrow minitube. The high flow velocities, moderate pressures (40–80 bar) and low temperatures (25–45 °C) lead to intense degasification and shear stress. The inactivation of the test microorganism Escherichia coli DH5α (E. coli DH5α) was determined before and after depressurization in the minitube, representing entirely chemical DPCD via dissolved CO2 and total inactivation comprising the effects of dissolved CO2 and mechanical effects, respectively. Compared to conventional DPCD pasteurization, which is mostly attributed to chemical effects, the additional mechanical effects increased the inactivation efficiency considerably