The Chemical Engineering Journal and the Biochemical Engineering Journal
Microbial cell disruption: role of cavitation
Abstract
A novel technique of using hydrodynamic cavitation for the large-scale disruption of yeast cells is described. Baker's yeast and brewer's yeast cells in a pressed yeast form were used. Cell disruption was monitored in the form of increase in soluble protein content. Disruption by hydrodynamic cavitation is compared with that obtained by established techniques such as blade blender and acoustic cavitation (ultrasonication).
The effect of cell concentration, time of treatment and number of passes in the flow loop system on the extent of cell disruption is reported. The energy efficiency of the hydrodynamic cavitation setup is compared with that of established techniques. Hydrodynamic cavitation was found to be at least an order of magnitude more energy efficient than established techniques such as ultrasonication or blade blender (mixer).
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Cited by (136)
Recent developments and future outlooks of hydrodynamic cavitation as an intensification technology for renewable biofuels production
2023, Journal of Environmental Chemical EngineeringBiofuels represent one of the most interesting candidates to replace fossil fuels and to reduce the global warming issues. Process intensification techniques able to maximize the biofuel yields minimizing the energy consumption are recently studied by researchers with encouraging results. Among them, Hydrodynamic cavitation (HC) appears a promising method, especially when feedstock hard-to-decompose are used (waste oil, lignocellulosic biomass, plastic wastes). This review is focused on the strengths and weaknesses of HC-assisted processes to produce three biofuels (biodiesel, bioethanol and biogas) starting from waste/non-edible oils in the case of biodiesel and lignocellulosic biomass for bioethanol and biogas, where HC is applied in the pretreatment units. The influence of operative conditions and the design of the cavitation device on the HC effectiveness together with three cavitation models were summarized and discussed in detail. Finally, the comparison in terms of yields, energy consumption and process scale with conventional technologies is made, highlighting the challenges and limitations which still need to be addressed before HC-assisted processes can be scaled-up. It is found that the HC- assisted biodiesel production enhances the yields of over 99% in a short period of time starting from different waste oils, with a high-purity level that meet the standards set by EN 14214 and ASTM D6751. The use of the HC-assisted lignocellulosic biomass pretreatment results in high lignin removal (60%) by consuming 4 times less energy than ultrasound-assisted processes (3.65 MJ/kg and 14.4 MJ/kg, respectively), fundamental to achieve a more effective production of bioethanol and biogas from lignocellulosic wastes.
Acoustic droplet vaporization for on-demand modulation of microporosity in smart hydrogels
2023, Acta BiomaterialiaMicroporosity in hydrogels is critical for directing tissue formation and function. We have developed a fibrin-based smart hydrogel, termed an acoustically responsive scaffold (ARS), which responds to focused ultrasound in a spatiotemporally controlled, user-defined manner. ARSs are highly flexible platforms due to the inclusion of phase-shift droplets and their tunable response to ultrasound through a mechanism termed acoustic droplet vaporization (ADV). Here, we demonstrated that ADV enabled consistent generation of micropores in ARSs, throughout the entire thickness (∼5.5 mm), utilizing perfluorooctane phase-shift droplets. Size characteristics of the generated micropores were quantified in response to critical parameters including acoustic properties, droplet size, and shear elastic modulus of fibrin using confocal microscopy. The findings showed that the length of the generated micropores correlated directly with excitation frequency, peak rarefactional pressure, pulse duration, droplet size, and indirectly with the shear elastic modulus of the fibrin matrix. The ADV-generated micropores in ARSs were further compared with cavitation-mediated micropores in fibrin gels without droplets. Additionally, the Keller-Miksis equation was used to predict an upper bound for micropore formation in ARSs at varying driving frequencies and droplet sizes. Finally, our in vivo studies showed that host cell migration following ADV-induced micropore formation was frequency-dependent, with up to 2.6 times higher cell migration at lower frequencies. Overall, these findings demonstrate a new potential application of ADV in hydrogels.
Interconnected micropores within a hydrogel can facilitate many cell-mediated processes. Most techniques for generating micropores are typically not biocompatible or do not enable controlled, in situ micropore formation. We used an ultrasound-based technique, termed acoustic droplet vaporization, to generate microporosity in smart hydrogels termed acoustically responsive scaffolds (ARSs). ARSs contain a fibrin matrix doped with a phase-shift droplet. We demonstrate that unique acoustic properties of phase-shift droplets can be tailored to yield spatiotemporally controlled, on-demand micropore formation. Additionally, the size characteristics of the ultrasound-generated micropores can be modulated by tuning ultrasound parameters, droplet properties, and bulk elastic properties of fibrin. Finally, we demonstrate significant, frequency-dependent host cell migration in subcutaneously implanted ARSs in mice following ultrasound-induced micropore formation in situ.
Future trends and promising applications of industrial sonochemical processes
2022, Energy Aspects of Acoustic Cavitation and Sonochemistry: Fundamentals and EngineeringDuring cavitation, nucleation, growth, and subsequent collapse of microbubbles in a liquid medium result in the generation of high temperature and pressure locally at millions of locations within, and in the immediate vicinity of the collapsing cavity in the sonochemical reactor. These effects have been effectively utilized to promote and intensify various physicochemical transformations in numerous applications in chemical synthesis via reducing the reaction time, increasing the reaction yield, switching of the reaction pathways, and initiation of the chemical reactions due to the formation of reactive free radicals. This chapter highlights various applications and future trends of the cavitation phenomenon involving intensification of various unit operations and processes in water and wastewater, biotechnology, material science, food and beverage, petroleum, textile processing, and other allied industries. For each of the applications, improvement demonstrated by ultrasound and ultrasonic cavitation over the conventional method is presented. The typical challenges in each of these segments are also presented.
The antioxidant capacity of cell-free extracts from Lactobacillus plantarum NJAU-01 obtained by using different cell disruption methods was determined. The efficacy of various methods, including high-pressure treatment (HIP), lysozyme combined with ultrasound treatment (LCU), glycine treatment (GLY), and frozen-thawed treatment (FAT) was studied. The results showed that the bacterial suspension in the HIP group visibly had the least intact cells per visual field compared with the other groups, followed by the LCU group. The HIP group possessed 5.12 lg CFU/mL viable bacteria, which was significantly lower than that of the other groups after cell disruption from the initial 9 lg CFU/mL. The protein concentration of the cell-free extract from the HIP group was higher than that of the other groups with abundant protein bands and band intensities. The HIP group presented significantly higher total antioxidant capacity and superoxide dismutase and glutathione peroxidase activities than the other groups. Our data suggest that HIP can be a preferable method to obtain cell-free extracts with excellent antioxidant capacity for further exploring the underlying antioxidant mechanism of Lactobacillus plantarum NJAU-01.
Safe water and technology initiative for water disinfection: Application of natural plant derived materials
2021, Journal of Water Process EngineeringSafe drinking water is the necessity of life. The present study reveals use of natural resources such as plant extracts and natural oils for water disinfection. Differences between oil and water soluble additives were highlighted for plant extracts and insoluble natural oils. A hybrid hydrodynamic cavitation process was quite effective in both the cases and high rates of disinfection were achieved. Studies were reported using oils (ginger, turmeric, lavender, tulsi) and rhizome derived plant extracts such as ginger, turmeric and mango ginger, as additives in process intensification (0.1% v/V). A vortex based cavitation device (vortex diode, nominal capacity 1 m3/h) was used with pressure drop of 1 bar. A high disinfection of 96% and 88% was obtained in 15 min for ginger oil and mango ginger extract respectively as compared to 44% using cavitation alone. Acoustic cavitation gave 94% and 30% disinfection with and without additive-mango ginger extract. The FTIR analyses before and after cavitation, with ginger additive, showed no by-products formation and indicated gingerol as active component in disinfection. The per-pass disinfection values were also higher, up to 5 times than cavitation alone. Hybrid hydrodynamic cavitation using natural plant derived materials can offer a promising technology alternative in water disinfection.
Microbial disinfection of water using hydrodynamic cavitational reactors
2021, Journal of Water Process EngineeringWater disinfection is gaining importance with increasing waterborne diseases and associated impacts on human health. An approach based on hydrodynamic cavitation (HC) is highly beneficial for water disinfection. The physical and chemical transformation that occurred during HC is useful for microbial inactivation. The selection of a cavitation chamber/geometry plays a crucial role in the HC performance and energy requirements. It depends on serval factors such as operation, maintenance, wearing internal parts of geometry, frequency of replacement of parts of the cavitational chamber. The present review summarizes the work on HC-assisted water disinfection. A detailed analysis has been presented on the understanding mechanism of HC-assisted microbial disinfection and operational parameters such as type and selection of constriction area. Handpump is used for providing the disinfected water to rural masses in developing and under-developing nations. Detailed guidelines have been presented on modified water handpump base on principles of hydrodynamic cavitation. HC is considered a highly energy-intensive operation and provides significant benefits compared to existing microbial methods. Substantial efforts are required for the development of an energy-efficient hydrodynamic cavitation technique for microbial water disinfection.