Nanobubble Water Research Articles

Metagenomic analysis reveals metabolic mechanism of enhancing lignocellulosic anaerobic digestion mediated by CO2/O2-nanobubble water

Nanobubble water (NW) has been reported to enhance anaerobic digestion (AD), but its influence on the metabolic pathways of microorganisms remains unclear. In this study, the specific methane yields of rice straw in the CO2NW and O2NW treatments increased by 6.9% and 18.3%, respectively. The electron transport system (ETS) and coenzyme F420 activities were enhanced by the addition of NW. Metagenomic analysis showed that the abundances of most enzymes in the acidification were significantly increased by both CO2NW and O2NW. Regarding methanogenesis, CO2NW promoted the expression of genes encoding enzymes of hydrogenotrophic methanogenesis, while O2NW stimulated both the acetoclastic and hydrogenotrophic methanogenesis. With the addition of O2NW, the expressions of modules related to the tricarboxylic acid (TCA) cycle and oxidative phosphorylation were enhanced, resulting in increased ATP production. This study provided fundamental evidence of the metabolic pathways of microorganisms mediated by NW at each stage of AD.

Dynamic viscosity of water containing large-sized nanobubbles simulated with coarse-grained molecular dynamics model

Nanobubbles have received widespread interest due to prospective applications in various disciplines. A crucial approach to investigating nanobubbles is molecular dynamics simulation. However, investigating large-sized bulk nanobubbles requires expensive computer resources. By coarsening the water molecules, the computational complexity can be significantly reduced, making the investigation of large-sized nanobubbles possible. This article presents simulations and analysis of the microscopic characteristics of water containing large-sized nanobubbles using coarse-grained molecular dynamics, especially, the Green-Kubo formula is used to calculate the dynamic viscosity. We first observe the effects of temperature, pressure and diameter on the viscosity of nanobubble water. The results indicate that higher temperature leads to lower viscosity of nanobubble water while higher pressure leads to higher viscosity of nanobubble water. Additionally, it is observed that the viscosity of nanobubble water decreases gradually as the diameter of the nanobubble increases. It is a remarkable fact that the viscosity of nanobubble water is lower than that of water at the same temperature and pressure, which means the viscosity of water can be reduced with the addition of nanobubble. At last, a viscosity correction model for nanobubble water at room temperature is successfully developed.

Effects of nano-bubble water on anaerobic co-digestion of cabbage waste and cow manure under mesophilic and thermophilic conditions

ABSTRACT The impact of four nano-bubble water (NBW) additions on the hydrolysis rate, methane yield, and microbial community of co-digestion of cabbage waste (CW) and cow manure (CM) under mesophilic and thermophilic conditions were investigated. Adding NBW under mesophilic conditions promoted hydrolysis, and the highest soluble chemical oxygen demand of the mesophilic digesters with the addition of CO2-NBW increased by 15.86%. Methane yield in the mesophilic digesters with Air-NBW and CO2-NBW increased by 17.54% and 14.72%, respectively. Moreover, the addition of NBW further accelerated the methane yield rate under mesophilic conditions. Due to the influence of thermophilic temperature, the impact of NBW addition on hydrolysis, methane yield, and methane yield rate in the thermophilic digesters did not differ significantly from the control. The addition of Air-NBW and N2-NBW in the thermophilic digesters resulted in only marginal increases in methane yield, by 1.09% and 5.61%, respectively. NBW addition enhanced both the abundance and diversity of microbial communities in both mesophilic and thermophilic digesters. The addition of NBW represents a promising technological advancement for enhancing the efficiency of anaerobic co-digestion of CW and CM.

Effect of CO2 Nanobubble Water on the Fracture Properties of Cemented Backfill Materials under Different Aggregate Fractal Dimensions

In order to cope with climate change and achieve the goal of carbon neutrality, the use of carbonization technology to enhance the performance of cement-based materials and achieve the purpose of carbon sequestration has become a very promising research direction. This paper considers the use of CO2NBW as mixing water for cement-based materials, aiming to improve the carbonization efficiency of materials to achieve the goal of carbon neutrality. This time, the effect of CO2NBW on cementitious filling materials under different aggregate fractal dimensions was studied through uniaxial compression tests and acoustic emission technology. The effect of CO2NBW on the mechanical properties and crack evolution of the material was discussed. The results showed that CO2 nanobubbles significantly improved the strength of cemented filling materials under different fractal dimensions, and the uniaxial compressive strength was most significantly improved by 23.04% when the fractal dimension was 2.7824. In addition, the characteristics of acoustic emission ring counts and energy parameters indicate that CO2 nanobubbles help improve the overall pore structure of the sample, affecting the macroscopic strength. However, the addition of CO2 nanobubbles reduces the limit energy storage ratio of elastic strain energy, which indicates that excessive CO2 concentration may affect the hydration reaction of the cementing material.

Alleviation of volatile fatty acids inhibition in anaerobic digestion of swine manure with nano-bubble water supplementation

Nano-bubble water (NBW) was applied to anaerobic digestion (AD) to alleviate volatile fatty acids (VFAs) inhibition, improve the buffering capacity and CH4 production in this work. Results indicated that NBW accelerated the consumption of VFAs and prevented inhibition due to VFAs accumulation. Additionally, NBW facilitated a rapid increase in partial alkalinity (PA) and total alkalinity (TA) as well as a corresponding rapid decrease in intermediate alkalinity (IA)/PA and VFA/TA, thereby improving buffering capacity and alleviating VFAs inhibition. Moreover, CH4 production improved by more than 12.2% by NBW. Similarly, the activities of the extracellular hydrolases and coenzyme F420 increased. Besides, NBW increased the abundance of microbial community and strengthened the metabolic pathways of hydrogenotrophic methanogens, which could be the intrinsic mechanism by which NBW alleviated VFAs inhibition, improved system stability, and increased CH4 production. This study demonstrates that NBW supplementation can be an effective method for mitigating frequent VFAs inhibition.

Effect of nanobubble water on the mechanical properties and carbon sequestration efficiency of concrete cured under various conditions

Carbon consuming concrete (CCC) represents an advanced sustainable concrete designed to optimize carbon sequestration efficiency. This study conducted preliminary tests on curing conditions to evaluate the effects of nanobubble water on the strength and carbon sequestration efficiency of concrete cured under various conditions. The curing conditions were characterized by temperature, duration, and the type of curing water utilized. The precipitation method was employed to validate the variation in the CO2-capturing capacity of nanobubble water (NBW), essential for carbon fixation within cementitious composites, as temperatures increased. Subsequently, compressive strength test and chemical analyses were performed on CCC manufactured under different curing conditions. Analysis techniques comprise differential thermogravimetry (DTG) and Fourier transform infrared spectroscopy (FT-IR). The carbon sequestration efficiency of CCC was observed to increase with shorter curing durations, and high temperatures could boost both the strength and carbon sequestration efficiency of CCC.

Surface Cleaning of Oil Contaminants Using Bulk Nanobubbles.

The removal of oil from solid surfaces, such as textiles and plates, remains a challenge due to the strong binding affinity of the oil. Conventional methods for surface cleaning often require surfactants and mechanical abrasion to enhance the cleaning process. However, in excess, these can pose adverse effects on the environment and to the material. This study investigated how bulk nanobubble water can clean oil microdroplets deposited on surfaces like glass coverslips and dishes. Microscopy imaging and further image analysis clearly revealed that these microdroplets detached from both hydrophobic and hydrophilic surfaces when washed with bulk nanobubble water within a fluidic microchannel. Oil contaminant cleaning was also conducted in water as mobile phase to mimic the circumstances that occur in a dishwasher and washing machine. Cleaning on a larger scale also proved very successful in the removal of oil from a porcelain bowl. These results indicate that nanobubble water can easily remove oil contaminants from glass and porcelain surfaces without the assistance of surfactants. This is in stark contrast to negligible results obtained with a control solution without nanobubbles. This study indicates that nanobubble technology is an innovative, low-cost, eco-friendly approach for oil removal, demonstrating its potential for broad practical applications.

Hydrogen nanobubbles and oxidative windows: Investigating how varying hydrogen concentrations influence seed germination and stress defense

The hydrogen molecule can effectively regulate plant growth and development, improving plant resistance to abiotic stresses. However, studies regarding the optimal concentration of hydrogen and the associated mechanisms of action in organisms are lacking. This study showed that the maximum germination rate of radish seeds decreased from 90 % to 50 % under the stress of cadmium ions (Cd2+), and hydrogen nanobubble (NB) water significantly alleviated the stress effect of Cd2+ on radish seed germination. A hydrogen concentration of 0.8 ppm had the best effect, reducing Cd2+ accumulation in radish seeds by 63.23 % and increasing the maximum germination rate from 50 % to 65 %. At concentrations exceeding 1.2 ppm, the beneficial effect of hydrogen was weakened or even reversed. Consequently, we integrated the concept of the oxidative window into a REDOX balance model and demonstrated that an appropriate hydrogen concentration can effectively maintain the REDOX state within organisms. Transcriptome sequencing analysis revealed that hydrogen NB water modulated Cd2+ absorption and accumulation in seeds by regulating cell wall components, alleviating oxidative stress through oxidoreductase activity, and enhancing nutrient synthesis and metabolism. This collectively alleviated the inhibitory effect of Cd2+ on seed germination. This study is helpful for further understanding the effect of hydrogen concentration on the REDOX balance of seed germination, providing a theoretical basis for selecting hydrogen concentration to improve its effectiveness in agricultural fields.

Use of Nanobubbles to Improve Mass Transfer in Bioprocesses

Nanobubble technology has emerged as a transformative approach in bioprocessing, significantly enhancing mass-transfer efficiency for effective microbial activity. Characterized by their nanometric size and high internal pressure, nanobubbles possess distinct properties such as prolonged stability and minimal rise velocities, allowing them to remain suspended in liquid media for extended periods. These features are particularly beneficial in bioprocesses involving aerobic strains, where they help overcome common obstacles, such as increased culture viscosity and diffusion limitations, that traditionally impede efficient mass transfer. For instance, in an experimental setup, nanobubble aeration achieved 10% higher soluble chemical oxygen demand (sCOD) removal compared to traditional aeration methods. Additionally, nanobubble-aerated systems demonstrated a 55.03% increase in caproic acid concentration when supplemented with air nanobubble water, reaching up to 15.10 g/L. These results underscore the potential of nanobubble technology for optimizing bioprocess efficiency and sustainability. This review delineates the important role of the mass-transfer coefficient (kL) in evaluating these interactions and underscores the significance of nanobubbles in improving bioprocess efficiency. The integration of nanobubble technology in bioprocessing not only improves gas exchange and substrate utilization but also bolsters microbial growth and metabolic performance. The potential of nanobubble technology to improve the mass-transfer efficiency in biotechnological applications is supported by emerging research. However, to fully leverage these benefits, it is essential to conduct further empirical studies to specifically assess their impacts on bioprocess efficacy and scalability. Such research will provide the necessary data to validate the practical applications of nanobubbles and identify any limitations that need to be addressed in industrial settings.

Evolution and stability of bubbles in cement-based materials under low air pressure: A Theoretical and experimental Study

In recent years, more and more infrastructures are being built in high-altitude regions where the atmospheric pressure is lowered. However, low atmospheric pressure affects bubble stability, which deteriorates the frost resistance of concrete and the sustainability of civil infrastructures in high-altitude regions. Currently, the evolution of bubbles in cement-based materials under low air pressure is unclear. Therefore, we developed the bubble dynamic differential equation which considering the viscosity of cement paste to describe bubble evolution and stability in cement-based materials; investigated the effect of nano-bubble water (NBW) on bubble stability in cement-based materials; and revealed the stabilization mechanism of bubbles reinforced by NBW. An experimental apparatus that integrates pressure regulating, bubbling, observation, and data recording is designed. The high-precision microscope and air-void analyzer are employed to study the dynamic evolution of bubble distribution over time and the hardened air-void parameters. The bubble dynamic differential equation indicates that the decrease of initial bubble size can improve bubble stability. The experimental results show that the average bubble diameter at low air pressure (0.5P) is larger than that at standard air pressure (P), and bubbles evolve more rapidly at 0.5P; when NBW is used, the average bubble diameter at P and 0.5P is reduced by 24.5% and 48.8%, respectively, and bubbles evolve more slowly. The stabilization principle of bubbles reinforced by NBW is discussed. It is proved that low atmospheric pressure affects the generation and evolution of bubbles, while NBW can reduce initial bubble size and improve bubble stability in cement-based materials. This research not only establishes bubble dynamic differential equation in cementitious materials, but also proposes an effective approach to improve bubble stability of cement-based materials at low atmospheric pressure, which promotes the sustainable development of infrastructures in high-altitude regions.

Effects of nanobubble water on digestate soaking hydrolysis of rice straw

This study investigated the performance of combined nanobubble water (NW) and digestate in the soaking hydrolysis process. Two types of NW (CO2NW and O2NW) with digestate were used to soak rice straw for 1, 2, 3, 5, and 7 days. During soaking process, the volatile fatty acids (VFA) concentration in the treatment with O2NW and digestate for 3 days (O2NW-3 d) reached 7179.5 mg-HAc/L. Moreover, the highest specific methane yield (SMY) obtained in this treatment could reach 336.7 NmL/gVS. Although the addition of NW did not significantly increase SMY from digestate soaking, NW could accelerate the rate of methane production and reduce digestion time of T80. The enrichment of Enterobacter in the soaking process was observed when using CO2NW and O2NW as soaking solutions which played important roles in VFA production. This study provides a new insight into environment-friendly enhanced crop straw pretreatment, combining NW and digestate soaking hydrolysis.

Impact of using XP-endo finisher and nanobubble water during EDTA dentin conditioning on TGF-β1 release in regenerative endodontic procedures.

Transforming Growth Factor-Beta 1 (TGF-β1) plays a crucial role in the success of Regenerative Endodontic Procedures (REPs) as they directly impact the proliferation and differentiation of stem cells. TGF-β1 is released by conditioning of the dentin matrix using 17% EDTA. EDTA was found to have deleterious effects on dentin especially in immature teeth with fragile dentin walls. Decreasing the irrigation time was reported to decrease these effects. Accordingly, enhancement and activation of the EDTA solution to maintain its efficiency in TGF-β1 release from dentin and thus compensating the reduction in irrigation time was employed. EDTA solution was enhanced by adding Nanobubble (NB) water which contains oxygen filled cavities less than 200nm in diameter. Additionally, EDTA was activated with XP-endo Finisher rotary file. The aim of this study was to assess the impact of NB enhancement and/or XP-endo Finisher activation of the EDTA solution on the TGF-β1 release from dentin. Fifty standardized root segments with open apex were allocated to two main groups according to whether EDTA was enhanced with NB water or not, and within each group whether XP-endo Finisher activation was used or not in addition to a Negative Control group. The concentration of the released TGF-β1 in the root canal was measured using enzyme-linked immunosorbent assay (ELISA). The statistical analysis was done using the Shapiro- Wilk, Kolmogorov Smirnov, ANOVA and Post-hoc Tukey tests. All groups released a considerable amount of TGF-β1 with the highest values in the EDTA/NB/XP group, followed by EDTA/NB, EDTA/DW/XP, EDTA/DW and Negative Control groups respectively. The results of this study suggest that NBs can promote the success of REPs since it revealed a significant increase in the TGF-β1 release following its use in the enhancement of the EDTA solution. A comparable effect was obtained by XP-endo finisher activation of the EDTA solution. The combined use of NBs and XP-endo Finisher can be a promising addition in REPs. Accordingly, Enhancement and activation of the EDTA solution may compensate decreasing the EDTA irrigation time attempted to avoid the deleterious effect of EDTA on dentin.

Environmentally Friendly Approach for Treatment Textile Wastewater by Nanobubble Water Technology and Enzymes

One of the most important issues about textile industry is its negative environmental impacts because of the pollution produced. Herein, decolorization processes of different-colored reactive dyeing baths using eco-friendly ways; nanobubbles and enzymes, was discussed. Decolorizations were evaluated by examining the transmittance and chemical oxygen demands of the treated wastewater baths were measured. The results showed that nanobubbles could be used in decolorization while laccase and peroxidase enzymes increased the decolorization effect of nanobubbles. In addition to the decolorizing effect of nanobubbles, it was an important environmental advantage that the corresponding process provided lower chemical oxygen demand than that in the untreated wastewater. The results of the study reveal that it is possible to use nanobubble in decolorization and this technology is an important wastewater treatment technology in protecting the environment by reducing the chemical oxygen demand of wastewater.

Synchronous improvement of methane production and digestate dewaterability in sludge anaerobic digestion by nanobubble

The subsequence anaerobic digestion (AD) of dewatered sludge (DWS) from wastewater treatment plants necessitates an emphasis on enhancing methane production and dewaterability. The effect of different nanobubble water (NBW) on AD of DWS was investigated under mesophilic conditions. Cumulative methane production was improved by 9.0–27.8% with the addition of different NBW (Air, CO2, He, and N2). NBW improved methanogenic performance by significantly enhancing the hydrolysis of sludge AD. Results from the digestate, the capillary suction time, specific resistance to filtration, and moisture content could be decreased by 14.6–18.2%, 18.8–29.6%, and 13.6–19.5%, respectively. The addition of NBW can improve the dewaterability of digestate by reducing the digestate particle size and increasing the zeta potential of digestate. The addition of NBW significantly increased methane production and improved dewaterability in AD; Air-NBW showed the best improvement.

Curing of Concrete Specimens Containing Metakaolin, Zeolite, and Micro-/Nanobubble Water in Seawater

Curing of Concrete Specimens Containing Metakaolin, Zeolite, and Micro-/Nanobubble Water in Seawater

Enhancing tomato fruit antioxidant potential through hydrogen nanobubble irrigation.

Eating fruits and vegetables loaded with natural antioxidants can boost human health considerably and help fight off diseases linked to oxidative stress. Hydrogen has unique antioxidant effects. However, its low-solubility and fast-diffusion has limited its applications in agriculture. Integration of hydrogen with nanobubble technology could address such problems. However, the physiological adaptation and response mechanism of crops to hydrogen nanobubbles is still poorly understood. Antioxidant concentrations of lycopene, ascorbic acid, flavonoids, and resveratrol in hydrogen nanobubble water drip-irrigated tomato fruits increased by 16.3-264.8% and 2.2-19.8%, respectively, compared to underground water and oxygen nanobubble water. Transcriptomic and metabolomic analyses were combined to investigate the regulatory mechanisms that differed from the controls. Comprehensive multi-omics analysis revealed differences in the abundances of genes responsible for hormonal control, hydrogenase genes, and necessary synthetic metabolites of antioxidants, which helped to clarify the observed improvements in antioxidants. This is the first case of hydrogen nanobubble water irrigation increasing numerous natural antioxidant parts in fruits. Considering the characteristics of hydrogen and the application of the nanobubble technology in agriculture, the findings of the present study could facilitate the understanding of the potential effects of hydrogen on biological processes and the mechanisms of action on plant growth and development.

Advantages of hydrogen nanobubble-rich concrete in workability and mechanical properties

This study investigates the potential benefits of using the 150 nm level Hydrogen Nanobubble Water (HNBW) in cement concrete. Given the significant greenhouse gas emissions associated with the cement and concrete industry, enhancing building materials performance and environmental friendliness becomes crucial. In this work, experiments were conducted to evaluate the various properties of this particular concrete formulation such as hydration heat, compressive strength, slump, air content, water absorption, electrical resistivity, rapid chloride permeability, and SEM. The results of the analysis showed that the HNBW improved the workability of the concrete by 50%. The HNBW improved the mechanical properties and durability of the concrete, resulting in an increase in compressive strength of 18.03% at 3 days and over 6% at 7 and 28 days. It reduces water absorption while improving electrical resistivity and chloride permeability resistance. Additionally, SEM imaging confirms that HNBW contributes to a more compact structure with pore and micro-crack size, thereby improving the overall performance of the concrete. Therefore, hydrogen nanobubbles, as a nanomaterial, exhibit favorable effects in meeting the demands of concrete.

Enhancement of methane production from anaerobic digestion of Erigeron canadensis via O2-nanobubble water supplementation

Malignant invasive Erigeron canadensis, as a typical lignocellulosic biomass, is a formidable challenge for sustainable and efficient resource utilization, however nanobubble water (NBW) coupled with anaerobic digestion furnishes a prospective strategy with superior environmental and economic effectiveness. In this study, influence mechanism of various O2-NBW addition times on methanogenic performance of E. canadensis during anaerobic digestion were performed to achieve the optimal pollution-free energy conversion. Results showed that supplementation of O2-NBW in digestion system could significantly enhance the methane production by 10.70–16.17%, while the maximum cumulative methane production reached 343.18 mL g−1 VS in the case of one-time O2-NBW addition on day 0. Furthermore, addition of O2-NBW was conducive to an increase of 2–90% in the activities of dehydrogenase, α-glucosidase and coenzyme F420. Simultaneously, both facultative bacteria and methanogenic archaea were enriched as well, further indicating that O2-NBW might be responsible for facilitating hydrolytic acidification and methanogenesis. Based on Kyoto Encyclopedia of Genes and Genomes (KEGG) cluster analysis, provision of O2-NBW enhanced the metabolism of carbohydrate and amino acid, translation as well as membrane transport of bacteria and archaea. This study might offer the theoretical guidance and novel insights for efficient recovery of energy from lignocellulosic biomass on account of O2-NBW adhibition in anaerobic digestion system, progressing tenor of carbon-neutral vision.

Nanobubble water promotes anaerobic digestion of high-solids cattle manure under mesophilic and thermophilic conditions

The gradual increase in cattle farming has led to a huge production of cattle manure (CM), but the conventional treatment methods are less efficient. In this study, the treatment method of anaerobic digestion (AD) of high-solids CM by combining nanobubble water (NBW) with different gases was proposed to present a new idea for the reduction, harmlessness, and resourcefulness of CM. It was found that the performance of the digester with added NBW was better than the control. Among them, the cumulative methane yield T-Air: 227.09 mL g−1 VSadded and T-CO2: 226.12 mL g−1 VSadded increased by 17.72 % and 17.22 %, respectively, compared with the control T: 192.90 mL g−1 VSadded under thermophilic conditions. Under mesophilic conditions, M-Air: 162.39 mL g−1 VSadded increased by 9.68 % compared with control M: 148.05 mL g−1 VSadded. Microbial communities analyzed at the genus level revealed that the relative abundance of bacteria favorable to hydrolysis and acid-producing processes, such as Defluviitalea, Haloplasma, and Bacillus, increased to varying degrees. Moreover, the relative abundance of archaea favorable for methanogenesis, such as Methanoculleus, Methanobrevibacter, and Methanosarcina, also increased to varying degrees. Therefore, the addition of NBW promoted the hydrolysis of high-solids CM, enhanced the stability of the reaction, improved the methanogenic performance, and increased the RA of favorable genera, which ultimately led to a better performance of the AD of high-solids CM.

Hydrogen Fertilization with Hydrogen Nanobubble Water Improves Yield and Quality of Cherry Tomatoes Compared to the Conventional Fertilizers

Although hydrogen gas (H2)-treated soil improves crop biomass, this approach appears difficult for field application due to the flammability of H2 gas. In this report, we investigated whether and how H2 applied in hydrogen nanobubble water (HNW) improves the yield and quality of cherry tomato (Lycopersicon esculentum var. cerasiforme) with and without fertilizers. Two-year-long field trials showed that compared to corresponding controls, HNW without and with fertilizers improved the cherry tomato yield per plant by 39.7% and 26.5% in 2021 (Shanghai), respectively, and by 39.4% and 28.2% in 2023 (Nanjing), respectively. Compared to surface water (SW), HNW increased the soil available nitrogen (N), phosphorus (P), and potassium (K) consumption regardless of fertilizer application, which may be attributed to the increased NPK transport-related genes in roots (LeAMT2, LePT2, LePT5, and SlHKT1,1). Furthermore, HNW-irrigated cherry tomatoes displayed a higher sugar–acid ratio (8.6%) and lycopene content (22.3%) than SW-irrigated plants without fertilizers. Importantly, the beneficial effects of HNW without fertilizers on the yield per plant (9.1%), sugar–acid ratio (31.1%), and volatiles (20.0%) and lycopene contents (54.3%) were stronger than those achieved using fertilizers alone. In short, this study clearly indicated that HNW-supplied H2 not only exhibited a fertilization effect on enhancing the tomato yield, but also improved the fruit’s quality with a lower carbon footprint.