Devices, systems and methods for nanobubble generation and uses thereof

Abstract

The present invention relates to devices and systems for generating nanobubbles. The present invention also relates to methods of generating nanobubbles. The devices, systems and methods of present invention generate nanobubbles by employing one or more mechanism such as cavitation hydrodynamics, shearing force mechanism, baffle jet system and membrane-based diffusion. The devices, systems and methods of present invention produce uniformly sized nanobubbles and find applications in preparing stable nanobubble-infused beverages with high concentration of nanobubbles.

Description

[0001] DEVICES, SYSTEMS AND METHODS FOR NANOBUBBLE GENERATION AND USES THEREOF

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to devices and systems for generating nanobubbles. It also pertains to methods for generating nanobubbles. The devices, systems and methods of the present invention generate stable nanobubbles at high concentrations. These nanobubbles find applications in the preparation of nanobubble-infused beverages, scientific research, and a wide range of industries including food industry, agriculture, aquaculture, water treatment, medical field, and others.

[0004] BACKGROUND OF THE INVENTION

[0005] Nanobubbles are ultrafine gas bubbles, typically with a diameter of less than 1 pm, and exhibit unique properties that enable them to remain suspended in liquids for extended periods. This stability is attributed to their small size and characteristic features such as high negative zeta potential, extremely low buoyancy, and random motion caused by Brownian movement.

[0006] Stable nanobubbles have negligible rising velocity and possess high -magnitude zeta potential values, which reduce the likelihood of bubble coalescence. As bubble size decreases, buoyancy diminishes and the bubbles remain longer in the liquid. Additionally, smaller bubbles have higher surface charge density, which increases the zeta potential and prevents clustering by repelling other bubbles.

[0007] Due to their hydrophobic nature, nanobubbles repel water and are attracted to particle surfaces, encapsulating them and promoting particle coagulation. When a nanobubble collapses in a liquid, the resulting inertial forces and conservation of mass cause the bubble wall to accelerate to supersonic speeds, leading to rapid internal heating. The collapse of thousands of nanobubbles releases a significant amount of energy, which can be harnessed for various applications.

[0008] This energy can also generate free radicals in surrounding water, resulting in strong oxidizing effects. Nanobubbles composed of air, oxygen, and / or ozone offer a chemical-free and environmentally friendly means of cleaning and sterilization. Their properties lend them to a variety of applications, including aeration, degradation of contaminants, filtration of suspended particles, and prevention of biofilm formation.

[0009] As a result, nanobubbles play a critical role in scientific research and a wide range of industries, such as agriculture, aquaculture, water treatment, and medicine, among others.

[0010] Their ability to enhance process efficiencies and target microscale environments with precision makes nanobubbles (NBs) invaluable across various applications. NBs have gained increasing attention due to their unique physicochemical properties and a wide range of potential uses, including detergent-free cleaning processes, tertiary oil recovery, foam fractionation, mineral flotation (Hampton, M. A., and Nguyen, A. V., 2009. Nanobubbles and the nanobubble bridging capillary force. Advances in Colloid and Interface Science, 154(1-2), 30-55; Maoming, F., Zhiyu, L. and Zhenghe, X., 2010b. Application of nanobubbles in the flotation of fine and ultrafine minerals. Minerals Engineering, 23(11-13), 1056-1061), food processing, intracellular drug delivery (Wang, X., Niu, D., Wu, Q., and Bo, Y., 2010. Intracellular delivery of therapeutic molecules using nanobubble ultrasound system. Journal of Controlled Release, 144(3), 370-378, biomedical engineering, medicine (Surendiran, A., Sandhiya, S., Pradhan, S. C., and Adithan, C., 2009. Novel applications of nanotechnology in medicine. Indian Journal of Medical Research, 129(6), 689-701), and environmental applications such as water aeration Tsuge, H., 2014. Micro- and nanobubbles: Fundamentals and applications. CRC Press; Agarwal, A., Ng, W. J., and Liu, Y., 2011. Principle and applications of microbubble and nanobubble technology for water treatment. Chemosphere, 84(9), 1175-1180).

[0011] Some of the unique characteristics of nanobubbles include their long-term stability in solution (Uchida, T., Oshita, S., Ohmori, M., Tsuno, T., Motoyama, M., and Mizunoya, W., 2011. Transmission electron microscopic observations of nanobubbles and their capture of impurities in waste water. Journal of Agricultural Chemistry and Environment, 1(1), 9-14), large specific surface area (Agarwal, A., Ng, W. J., and Liu, Y., 2011. Principle and applications of microbubble and nanobubble technology for water treatment. Chemosphere, 84(9), 1175-1180; Uchida, T., Oshita, S., Ohmori, M., Tsuno, T., Motoyama, M., and Mizunoya, W., 2011. Transmission electron microscopic observations of nanobubbles and their capture of impurities in waste water. Journal of Agricultural Chemistry and Environment, 1(1), 9-14), ability to retain gas at high internal pressures (Tyrrell, J. W. G., and Attard, P., 2001. Images of nanobubbles on hydrophobic surfaces and their interactions. Physical Review Letters, 87(17), 176104; Agarwal, A., Ng, W. J., and Liu, Y., 2011. Principle and applications of microbubble and nanobubble technology for water treatment. Chemosphere, 84(9), 1175-1180), presence of surface charge (Tsuge, H., 2014. Micro- and nanobubbles: Fundamentals and applications. CRC Press), and exceptional resistance to coalescence, collapse, bursting, or transformation into larger bubbles (Ushikubo, F. Y., Furukawa, T., Nakagawa, R., Enari, M., Makino, Y., Kawagoe, Y., Shiina, T., and Oshita, S., 2010. Evidence of nanobubbles in water and the change in zeta potential and surface tension. Chemistry Letters, 39(5), 540-543; Uchida, T., Oshita, S., Ohmori, M., Tsuno, T., Motoyama, M., and Mizunoya, W., 2011. Transmission electron microscopic observations of nanobubbles and their capture of impurities in waste water. Journal of Agricultural Chemistry and Environment, 1(1), 9-14).

[0012] The importance of nanobubbles across various industries is evident from their wide range of applications. Their high stability in liquids has led to significant use in wastewater treatment via flotation, as well as in biogas applications, including the control of methane emissions from agriculture. Nanobubbles are also utilized in the food industry and in the regulation of pH levels in liquids through the use of carbon dioxide.

[0013] Known and potential applications of nanobubbles include, but are not limited to, wastewater treatment, surface cleaning, froth flotation, ultrasound contrast agents, therapeutic drug delivery, drag reduction, enhancement of physiological activity in living organisms, bacterial sterilization, accelerated seed germination, and improved blood oxygenation. As such, numerous industries can benefit from the use of nanobubbles and the systems that generate them.

[0014] The generation of gaseous nanobubbles (NBs) through simple, efficient, and scalable methods is crucial for industrial adoption and for realizing the full potential of nanobubble-based applications. Traditional nanobubble generation methods primarily rely on hydrodynamic, acoustic, particle-induced, and optical cavitation.

[0015] Several nanobubble generators have been disclosed in the field in various patent documents. For example, U.S. Patent Application No. US2022331750A1 discloses a vacuum-assisted shear flow nanobubble generator system. U.S. Patent No. US10874996B2 describes a nanobubble generator with a specialized nozzle. U.S. Patent No. US11904366B2 relates to systems and methods for controlling the concentration of micro- and nanobubbles in a solution for product treatment. Indian Patent Application No. 1N201741039017 discloses a continuous shear nanobubble generator, while International Patent Application No. W02023240018A2 describes a diffuser-less nanobubble generator.

[0016] U.S. Patent No. US10814290B2 discloses a generator comprising a series of at least two sequential cavitation zones and shear planes to treat a source liquid solution and produce a nanobubble-containing liquid. Another patent, W02017096444A1, describes an apparatus in which nanobubbles are generated via two -stage hydrodynamic cavitation.

[0017] One of the key limitations of cavitation-based methods is that they are timeconsuming and present challenges in precisely controlling cavitation bubble size. Each method in the prior art has inherent limitations related to energy efficiency, cost, nanobubble yield, bubble quality and durability, and suitability for specific applications. Therefore, there remains a need for more efficient nanobubble generators that employ novel methods or combinations thereof to address at least some of these shortcomings.

[0018] Given the promising benefits and wide range of potential applications, various nanobubble generator types have been developed that utilize multiple hydrodynamic principles. These include swirl-type, static mixer-based, pressurized-dissolution, cavitation-type, and Venturi-based nanobubble generators. However, existing systems are often limited in terms of the density of nanobubbles produced and may not meet the requirements for applications demanding a high concentration of nanobubbles with uniform size distribution and high flux. Known generators also suffer from drawbacks such as poor stability, low yield, suboptimal energy efficiency, and inadequate zeta potential — underscoring the need for improved systems capable of producing stable, durable nanobubbles with uniform size.

[0019] Examples of nanobubble generators are disclosed in U.S. Patents US7874546B2; US7997563B2; and U.S. Patent Application Publication US2013 / 0034829A1. U.S. Patent US7874546B2 describes a fine bubble generator system comprising a fluid input, a fluid output, at least one gas input, and a plurality of fine bubble generators positioned between the fluid input and output. U.S. Patent US7997563B2 discloses a microbubble generator utilizing a swirling flow-generating vane nozzle connected coaxially to a vortex breakdown nozzle. U.S. Patent Application Publication US2013 / 0034829A1 describes an apparatus using a Venturi -type tube and a porous gas disperser with sub- picomole-sized holes, allowing gas to enter the liquid in preformed bubble form.

[0020] The existing nanobubble generators and methods fail to deliver nanobubbles that consistently exhibit a combination of high concentration, uniform size distribution, and extended lifetime. Each known system has trade-offs in performance, cost, and application compatibility. To address these unmet needs, the inventors of the present invention have developed novel nanobubble generators designed to overcome the limitations of prior art systems.

[0021] Current nanobubble generators face several limitations, including the need for high-pressure liquid injection, which leads to significant energy consumption. Additionally, the liquid-gas mixing processes within these generators may be impractical for in situ water remediation and other applications. Recirculation of the gas-liquid mixture can introduce contamination into the generator system. Furthermore, existing systems often lack precise control over bubble -size and uniformity. They also exhibit low resistance to corrosive chemicals, limiting their compatibility with reactive gases and solutions.

[0022] Ceramic membranes have been employed as bubbling diffusers in various wastewater treatment applications, including general wastewater treatment, landfill leachate treatment, and activated sludge treatment. However, commercial ceramic diffusers typically produce bubbles only in the millimeter range, with the smallest reported size being 0.51 mm. There is limited information available on techniques to control and reduce bubble-size using ceramic membranes, despite the importance of such knowledge for the development of efficient nanobubble generators.

[0023] For instance, U.S. Patent No. US11179684B2 discloses a device comprising a ceramic membrane with a first surface, an opposing second surface, and pores extending between them. The second surface defines a plenum with a first and an opposing second opening. The plenum is fluidly coupled to the pores at the membrane’s second surface. A hydrophobic porous coating layer is applied to the first surface of the membrane. The disclosed method involves generating nanobubbles by flowing gas through the openings into the plenum and subsequently through the membrane pores at the second surface, allowing the gas to exit the device as nanobubbles.

[0024] Similarly, Chinese patent application CN109876684A describes a laboratory - scale, controllable nanobubble generator that employs a nanoporous ceramic membrane as a separator. The membrane's pore size distribution is adjustable, and the membrane itself is easily replaceable. This design facilitates experimental studies on nanobubble generation by enabling control over parameters such as flow rate, gas type, and nanobubble size.

[0025] Therefore, there remains a need in the field for more energy-efficient nanobubble generators capable of effectively perfusing gas under pressure through nanoporous membranes into the surrounding fluid medium.

[0026] Oxygen is a fundamental element essential for sustaining life in the human body, with respiration being the primary means of oxygen intake. Additionally, oxygen present in water, beverages, and food can be absorbed — especially when these substances are enriched with high levels of oxygen. Once inhaled or absorbed, oxygen supports metabolism, increases energy levels, enhances mood and concentration, improves athletic performance, reduces stress, alleviates headaches and migraines, promotes better sleep, aids in the clearance of lactate and alcohol from the bloodstream, and contributes to the prevention of various diseases.

[0027] To enhance metabolism, many beverage and health drink manufacturers have introduced oxygen into their products by bubbling oxygen gas into the drinks. Some studies, such as those conducted by David King, suggest that consuming beverages infused with ultrafine oxygen bubbles improves athletic performance, particularly in endurance and recovery. Other studies indicate that oxygenated water may accelerate blood lactate clearance following exercise, although it does not appear to directly affect lactate kinetics.

[0028] In water, oxygen typically exists in a chemically bonded form, making it difficult to absorb oxygen directly from water or water-based beverages. To overcome this limitation, oxygen is infused into water or beverages to produce oxygen-enriched drinks.

[0029] The infusion of gases to create enriched beverages — such as carbonated and oxygenated drinks — has been practiced for many years. However, infused gases tend to diffuse out of the liquid over time, leading to significant oxygen loss shortly after infusion. Additionally, external factors such as temperature and pressure can influence the amount of dissolved oxygen (DO) that remains in the liquid.

[0030] According to Henry's Law, when the temperature of a liquid is uniform and remains constant, the concentration of a dissolved gas in the liquid is directly proportional to the partial pressure of the gas and Henry's constant for that specific gas. This relationship can be expressed as:

[0031] Coc P or C= kH P

[0032] Where C = Concentration of the dissolved gas in the liquid (mol / L)) kH = Henry’s constant mol / (Lx atm)

[0033] P = Partial pressure of the gas (atm)

[0034] Under standard pressure and room temperature conditions, the maximum achievable DO concentration in water is approximately 8.73 ppm. Thus, bottling operations wherein oxygen is bubbled into the beverage have been inefficient to increase DO concentration further.

[0035] Arriving at and / or maintaining a high level of DO in a beverage in ambient conditions has remained a challenge in the field.

[0036] Drinking water in urban areas is generally processed through filtration, reverse osmosis and UV irradiation. Concentration of DO in water in such urban water typically ranges between 5 to 9 mg / L (ppm) and preferably 8 mg / L (ppm). If the temperature rises, the solubility of oxygen decreases and vice versa. Typically, in order to increase DO saturation of the water, multiple rounds of recirculating the oxygen -mixed water through the oxygen source is resorted to. This results in the temperature of the oxygenated water rising owing to recirculation and consequently the DO level drops. Achieving higher oxygen saturation in water is therefore difficult to achieve by recirculation method.

[0037] CN1079374A discloses oxygen-containing beverage and manufacture method thereof. The oxygen-containing beverage disclosed in this patent document has oxygen content 8-80ml / l. W02006120747 discloses process and apparatus for producing oxygen-containing reducing aqueous beverage. Various other patent documents such as KR1020120111858, KR1020040020274, KR1020040024819 and KR1020000037316 disclose oxygen beverages and methods of preparation thereof. There is a need in the field to address the limitations associated with increasing the concentration of at least one gas — preferably oxygen — in beverages. Therefore, improved and efficient methods for preparing oxygen-enriched beverages are required. Additionally, there is a need to provide an alternative approach for infusing at least one gas, preferably oxygen, into beverages, such as in the form of nanobubbles.

[0038] In summary, current nanobubble generators and methods fall short in delivering nanobubbles with high concentration, uniform size distribution, and extended stability, often compromising on energy efficiency, cost, and application suitability. To overcome these limitations, the inventors have developed novel nanobubble generators that address the shortcomings of prior systems. There remains a clear need for energyefficient technologies capable of perfusing or delivering gases — particularly oxygen — via nanoporous membranes into fluids. This is especially critical for applications such as oxygen-enriched beverages, where improved methods for stable and efficient gas infusion, including nanobubbles, are essential.

[0039] OBJECTS OF THE INVENTION

[0040] It is therefore an objective of the invention to provide devices, systems and methods for nanobubble generation and use thereof.

[0041] An additional object of the invention is to provide nanobubble generators for producing nanobubbles using cavitation and shearing method.

[0042] Another objective is to provide an efficient way of producing stable and uniformly-sized nanobubbles with high concentration.

[0043] A further objective is to provide nanobubble generators capable of generating high concentration of nanobubbles in the out-flowing fluid per cycle.

[0044] Another objective is to produce nanobubbles that are in the range of 1- 500 nm in diameter, preferably 100 to 200 nm diameter and average or mean bubble size of less than or equal to 200 nm, preferably 50 to 200 nm, more preferably 200 nm.

[0045] A further objective is to provide energy-efficient nanobubble generators.

[0046] Still another objective is to produce nanobubbles that are chemical additive-free.

[0047] Another objective of the invention is to produce nanobubbles with uniform sizedistribution.

[0048] Another objective is to provide light and portable nanobubble generators. Another objective is to provide a source for making more durable nanobubbles that can last in the medium without collapsing for more than a month.

[0049] Yet another objective is to provide nanobubble generators capable of producing a greater density of nanobubbles.

[0050] Yet another objective of the invention is to generate nanobubbles with a very narrow bubble size-distribution.

[0051] Another objective is to provide systems and methods for infusing beverages with a high concentration of nanobubbles.

[0052] Yet another objective is to provide beverages infused with nanobubbles of at least one gas.

[0053] These and other objectives will become more readily apparent to the reader on closer scrutiny of the specification and drawings which describe the many embodiments of the invention.

[0054] SUMMARY OF THE INVENTION

[0055] The present invention provides devices, system and methods for nanobubble generation and use thereof.

[0056] In an embodiment, the present invention provides system for nanobubble generation comprising a liquid pressuring pump, gas injection system, and a nanobubble mixer featuring complex flow fluid cavities that exert a shear force on the liquid. The generator includes fluid inlet and outlet components. Gas is injected into the liquid at pump suction to facilitate mixing the gas into the fluid flowing medium. Microbubbles are generated by pump by cavitation. These microbubbles are then introduced into the nanobubble mixer, which incorporates liquid carriers and shearing cavities. The microbubbles under high-pressure, upon entering the complex shearing cavity, experience a robust shear force leading to their pulverization into nano -sized bubbles. The nanobubbles generated in the liquid have bubble diameter in range of 1 to 500 nm, preferably 100-200 nm and average or mean bubble diameter less than or equal to 200 nm, preferably 50-200 nm , more preferably 200 nm and demonstrates a total bubble concentration of 10 e8 bubbles [IO8] per milliliter with a high zeta potential in range of -1 mV to -50 mV, preferably -15 mV to -45 mV, more preferably - 44.3 mV. ln another embodiment, the present invention provides systems for nanobubble generation having a combination of at least one baffle jet and at least one additional cavitation-inducing component to generate nanobubbles. The baffle jet structure is capable of increasing turbulent energy along with creating cavitation as well. The nanobubbles generated predominantly have an average diameter of 200 nm or less. The generator comprises of multiple components that are in fluidic communication with each other and can be assembled together in any sequence to produce nanobubbles. In the preferred embodiment, the liquid and gas inlet component has at least one baffle jet leading on to a baffle, spiral and venturi assemblies.

[0057] In yet another embodiment, the present invention provides nanobubble generators and methods for preparing nanobubbles that employ membrane -based diffusion. The systems of present invention for nanobubble generation use gas pressure to perfuse gas through ceramic nanoporous membranes, generating nanobubbles via sealed diffusers that consist of nanoporous ceramic chambers.

[0058] In still another embodiment, the present invention provides systems and methods of infusing a beverage or drinking water with high concentration of at least one gas, preferably oxygen. The methods comprise converting at least one gas or oxygen into nanobubbles and infusing the obtained nanobubbles into beverage such as drinking water at regulated temperature to get optimal levels of dissolved gas or oxygen. The invention also provides beverages infused with nanobubbles of at least one gas such as oxygen-infused beverage.

[0059] As mentioned before, the potential applications of nanobubble technology are enormous and can be realized only if the deficiencies of the currently prevailing nanobubble generators are rectified. In order to increase yield, consistency, high energy efficiency and reduced cost, the inventors of the present invention have integrated hydrodynamics cavitation that produces microbubbles and shearing force to produce high concentration of nanobubbles with uniform size distribution. In the present invention, the shear plates in the assembly of shear plates are furnished with cavities of different shapes that allow to creates shear force to generate ultrafine nanobubbles in uniform size. In an embodiment, the inventors of the present invention have integrated cavitation hydrodynamics with at least one baffle jet to obtain predominantly uniform nanobubbles consistently with their novel-design bubble generators.

[0060] The nanobubble generators of the present invention have a combination of at least one baffle jet and at least one cavitation-inducing component to generate nanobubbles predominantly having 1 to 500 nm diameter, preferably an average of 200 nm or less diameter. The generators comprise of multiple components that are in fluidic communication with each other and can be assembled together in any sequence to produce nanobubbles. In the preferred embodiment, the liquid and gas inlet component has a baffle jet leading on to a baffle, spiral and venturi assemblies.

[0061] In another embodiment, the inventors of the present invention have designed energy-efficient nanobubble generators that perfuse gas under pressure through ceramic nanoporous membranes into a fluid medium surrounding the ceramic membrane. Preferably, these diffusers are sealed nanoporous ceramic chambers with one inlet which receives a gas under high pressure which perfuse through the nanopores in the ceramic to the surrounding fluid, creating nanobubbles.

[0062] In one embodiment the present invention provides a system for generating nanobubbles wherein mixing of at least one gas to the fluid is implemented at pump suction or pump inlet.

[0063] In another embodiment the present invention provides a hybrid system for generating nanobubbles wherein mixing of at least one gas and fluid is implemented at Venturi which may be present in at least one of first module, third and / or fourth module of the system.

[0064] In still another embodiment the present invention provides a membrane based system for generating nanobubbles wherein mixing of at least one gas is being implemented at surface of nonporous membrane.

[0065] In one embodiment the present invention provides that the fluid infused with nanobubbles as obtained at outlet of a first system for generating nanobubbles may be routed to the inlet of said first system or another second system fluidically connected to the first system in series, parallel, or a combination of series and parallel to generate large volumes and highly concentrated nanobubble-laden fluid. In another embodiment the present invention provides that the second system fluidically connected to the first system may generate nanobubbles based on same mechanism as of the first system or may generate nanobubbles based on mechanism different than the first system.

[0066] In an embodiment the present invention provides that concentration of nanobubbles generated in fluid is about 200 millions / ml or more, preferably about 500 millions / ml, more preferably about 675 millions / ml.

[0067] In an embodiment the present invention provides a system for generating nanobubbles comprising: at least one first chamber (1) for generating microbubbles in mixture of fluid and at least one gas for preparing microbubbles -laden fluid by hydrodynamic cavitation; and at least one second chamber (7) for transforming microbubbles generated by the first chamber to nanobubbles by shearing force, i) wherein the first chamber (1) has a proximal end comprising at least one inlet for fluid, at least one inlet for gas (2) and at least one pump , and a distal end for fluidically connecting the first chamber to the second chamber; and ii) wherein the second chamber (7) comprises assembly of shearing plates (3) arranged in at least one nanobubble mixer tube (6).

[0068] In a further embodiment, the present invention provides that the assembly of shearing plates comprises plurality of alternating male (10) and female (20) shearing plates.

[0069] In yet another embodiment the present invention provides that the male (10) and female (20) shearing plates comprises cavities or pockets therein which are circular or polygonal in shape.

[0070] In still another embodiment the present invention provides that the assembly of shearing plates (3) further comprises plurality of spacers (5) for maintaining free flow of fluid thereby creating sufficient shear force.

[0071] In a still further embodiment, the present invention provides that the device generates nanobubbles in a continuous fluid medium by integrating hydrodynamic cavitation and shearing force in a two-stage process.

[0072] In another embodiment the present invention provides that the pump maintains flow rate of the fluid at about 70 to 110 LPM (Litre per minute), preferably about 90 LPM. In a further embodiment the present invention provides that method of generating nanobubbles in a fluid by integrating hydrodynamic cavitation and shearing force in a two-stage process, comprising a first stage and a second stage wherein: i] in the first stage microbubbles are formed in a mixture of the fluid and at least one gas by generating cavitation to obtain microbubbles -laden fluid in at least one first chamber; and ii] in the second stage, the microbubbles obtained in i] are transformed into nanobubbles by subjecting the microbubbles-laden fluid to high pressure thereby inducing high shearing stress of about 60 to 100 Pa, preferably about 79 Pa in assembly of shearing plates in at least one second chamber to obtain nanobubbles.

[0073] In yet another embodiment the present invention provides that the cavitation is generated in the first stage by maintaining fluid pressure equal to or less than vapor pressure.

[0074] In still another embodiment the present invention provides that the microbubbles are generated in the first stage by controlled cavitation with a liquid -gas mixture maintained at about 2 to 12 %, preferably about 3% and a negative pressure of about -0.10 to -0.50 maintained at inlet of at least one first chamber of a system generating nanobubbles.

[0075] In a still further embodiment, the present invention provides that a pump in at least one first chamber of a system generating nanobubbles maintains flow rate of fluid at about 70 to 110 Litre per minute (LPM), preferably about 90 LPM.

[0076] In an embodiment the present invention provides that the second stage comprises feeding the microbubbles generated in the first stage to a nanobubble generator in at least one second chamber of a system generating nanobubbles with a liquid velocity of about 2 to 5 m / s and a liquid pressure of about 1 to 5 bar, preferably about 3 bar.

[0077] In a further embodiment the present invention provides that the second stage microbubbles-laden fluid is subjected to high shear stress of about 60 to 100 Pa, preferably about 79 Pa on walls of one or more of cavities or pockets in the assembly of shearing plates thereby converting microbubbles into nanobubbles. In yet another embodiment the present invention provides a system for generating nanobubbles comprising multiple modules in fluidic communication, assembled in any sequence, wherein the device comprises at least one first module (021), at least one second module (022), at least one third module (030) and at least one fourth module (040), wherein: i) the at least one first module (021) comprises a proximal end, a distal end, at least one inlet for fluid (024), at least one inlet for gas (025) positioned in a manner that it intercept flow of fluid from the at least one inlet for fluid (024) to deliver gas into the fluid entering the second module (022), plurality of baffle jets (026) positioned on walls of first module to induce flow pattern to egressing fluid, and wherein the distal end of first module is in fluid communication with proximal end of the second module; ii) the proximal end of the second module (022) abuts from the first module, expands and sports a baffle jet system on its inner walls until it converges at distal end wherein said distal end is in fluid communication with proximal end of the third module (030); hi) the third module comprises at least one spiraled convergent cone (027) at its core and the distal end of said third module is in fluid communication with proximal end (023) of the fourth module (040); iv) the fourth module comprises at its distal end (028) at least one fluid outlet which empties into a collection vessel; and wherein at least one of first module, second module, third module and fourth module are under negative pressure for generating cavitation

[0078] In still another embodiment the present invention provides that the inlet for fluid (024) in first module widens before the inlet of gas (025) enters said first module.

[0079] In another embodiment the present invention provides that the inlet for gas (025) in the system is positioned substantially perpendicular to the at least one inlet for fluid (024).

[0080] In a still further embodiment, the present invention provides that the third module (030) comprises a smooth outer wall and the at least one spiraled convergent cone (027) at its core induces spiral flow of the fluid along the third module. In an embodiment the present invention provides that the third module comprises plurality of spiral grooves (029) along surface of the spiral convergent cone (027) for increasing turbulence and for providing optimal shear force to reduce size of bubbles.

[0081] In a further embodiment the present invention provides that the spiral grooves (029) are contoured to at least one shape selected from circular, rectangular, or any other polygonal form to provide desired turbulence.

[0082] In yet another embodiment the present invention provides that the third module (030) further comprises at least one Venturi tube.

[0083] In a still further embodiment, the present invention provides that the system combines at least one baffle jet and at least one additional component generating cavitation.

[0084] In an embodiment the present invention provides that the system generates nanobubbles by integrating swirling, mixing, and Venturi effects by one or more baffle jet, spiral and Venturi components present in one or more of the first module, the second module, the third module and the fourth module.

[0085] In a further embodiment the present invention provides a method of generating nanobubbles by a system comprising multiple modules in fluidic communication with each other, comprising: i) mixing of fluid and at least one gas by at least one first module to obtain mixture of fluid and gas; ii) introducing mixture of fluid and gas obtained in i) tangentially into at least one second module to create swirl flow; hi) creating cavitation bubbles in the mixture of fluid and gas introduced in the second module in ii) by at least one baffle jet of the at least one second module; iv) subjecting the cavitation bubbles obtained in hi) to shear force by plurality of spiral grooves along surface of convergent cone of at least one third module to obtain bubbles of reduced size; v) subjecting the bubbles of reduced size of iv) to Venturi effect by at least one Venturi tube of the third module and / or at least one fourth module to obtain fluid laden with nanobubbles; and vi) collecting the fluid laden with nanobubbles in v) by at least one fluid outlet of the fourth module.

[0086] In yet another embodiment the present invention provides that the centerline of at least one second module embedded within the baffle structure is maintained at negative pressure of about -0.1 to -0.50 bar, preferably about -0.15 bar.

[0087] In still another embodiment the present invention provides that the flow rate of the fluid through the multiple modules is maintained at about 70 to 110 LPM, preferably about 90 LPM.

[0088] In a still further embodiment, the present invention provides that the system comprises a chamber having a proximal end (01) and a distal end (02) wherein the proximal end receives at least one inlet port such that a fluid enters said chamber through the inlet port and exits through at least one port on the distal end, and wherein the chamber comprises one or more membrane-based gas diffusers (03).

[0089] In an embodiment the present invention provides that the gas diffusers (03) are positioned in flow-stream in a manner to intercept direction of flow of fluid.

[0090] In a further embodiment the present invention provides that the gas diffusers (03) are positioned in flow-stream at substantially right angles to direction of flow of fluid.

[0091] In yet another embodiment the present invention provides that each gas diffuser comprises at least one elongated chamber composed of porous material having two opposing ends - a first end (04) and a second end (05).

[0092] In still another embodiment the present invention provides that the first end (04) accommodates a means for gas-injection into said elongated chamber while the second end (05) is sealed.

[0093] In a still further embodiment, the present invention provides that the one or more membrane-based gas diffusers (03) may be connected serially or individually to a gas source from where the gas is pumped under pressure.

[0094] In an embodiment the present invention provides that the coating of the gas diffusers (03) is of thickness between about 1 and 10 microns, preferably about 8 microns. In a further embodiment the present invention provides that the gas diffusers (03) comprise at least one outer porous membrane (06) constructed from a ceramic base material and coated with a-Al203(alumina).

[0095] In yet another embodiment the present invention provides that the porous membrane (06) is of length from about 100 to 1200 mm; preferably of about 500 mm and more preferably of about 140 mm.

[0096] In still another embodiment the present invention provides that the porous membrane (06) comprises an outer diameter (07) of thickness of about 4 to 200 mm, preferably about 1 to 20 mm, more preferably about 10 mm and an inner diameter (08) of thickness of about 1 to 100 mm, preferably about 2 to 10 mm, more preferably about 7 mm.

[0097] In a still further embodiment, the present invention provides that the porous membrane (06) comprises one or more channels ranging from about 1 to 160.

[0098] In an embodiment the present invention provides that the porous membrane (06) comprises pores of size of 1 pm or less, preferably about 1 to 500 nm, more preferably about 50 to 70 nm for generation of nanobubbles.

[0099] In a further embodiment the present invention provides that the the system employs membrane-based diffusion and perfuses gas under pressure through ceramic nanoporous membranes into the surrounding fluid medium thereby generating nanobubbles.

[0100] In yet another embodiment the present invention provides a method of generating nanobubbles by membrane based diffusion comprising injecting mixture of a fluid and at least one gas under pressure into one or more membrane -based gas diffuser to obtain fluid laden with nanobubbles, wherein the membrane-based gas diffuser is of thickness between about 1 and 10 microns, preferably about 8 microns and is constructed from a ceramic base material and coated with a-Al203(alumina).

[0101] In still another embodiment the present invention provides that the system comprises multiple systems for nanobubble generation in accordance with other embodiments of the present invention connected in series, parallel, or a combination of series and parallel to generate large volumes of nanobubble-laden fluid.

[0102] In a still further embodiment, the present invention provides system of infusing a beverage or fluid with high concentration of at least one gas wherein the system comprises using system as claimed in any one of claims, connected in series, parallel, or a combination of series and parallel.

[0103] In an embodiment the present invention provides a method of infusing a beverage or fluid with high concentration of at least one gas wherein the method comprises converting at least one gas into nanobubbles using any of the systems as described hereinabove and infusing the obtained nanobubbles in the beverage or fluid at regulated temperature to get optimal levels of dissolved gas.

[0104] In a further embodiment the present invention provides that a beverage or fluid infused with nanobubbles of at least one gas wherein the beverage has been infused with the nanobubbles by using any of the systems as described hereinabove and any of the methods as described hereinabove.

[0105] In still another embodiment the present invention provides a method of preparation of water infused with nanobubbles of at least one gas. Said method comprises comprising optionally treating water prior to infusing nanobubbles by one or more systems as described above with ozone followed by passing through one or more filters of suitable pore size and / or treatment by salts of one or more alkali metals and / or alkaline earth metals to obtain treated water; generating and infusing nanobubbles in water or treated water of a) by these systems to obtain water infused with nanobubbles of at least one gas; and optionally treating water infused with nanobubbles of at least one gas of step b] with ozone followed by passing through one or more filters of suitable pore size.

[0106] In yet another embodiment the present invention provides use of any of the systems and methods as described hereinabove for generating nanobubbles for food industry, agriculture, aquaculture, water treatment, medical field, wastewater treatment, surface cleaning, froth flotation, nanobubbles as an ultrasound contrast agent, therapeutic drug delivery, drag reduction, promotion of the physiological activity of living organisms, sterilization of bacteria, accelerated seed germination and improved blood oxygenation, detergent-free cleaning processes, tertiary oil recovery, foam fractionation, mineral flotation, food-processing, intracellular drug delivery, biomedical engineering, medicine, and environmental applications. DESCRIPTION OF THE DRAWINGS

[0107] The detailed description is set forth with reference to the accompanying figures. The use of the same reference numbers in different figures indicates similar or identical items or features.

[0108] Figure 1 illustrates steps of an exemplary method of the present invention.

[0109] Figure 2 illustrates schematic representation of the nanobubble generator system according to one embodiment.

[0110] Figure 3 illustrates exploded view of the nanobubble generator system.

[0111] Figure 4 illustrates sectional view of nanobubble mixer.

[0112] Figure 5 illustrates sectional view of shearing plate assembler.

[0113] Figure 6 illustrates shearing plate assembly.

[0114] Figure 7 A illustrates male shearing cavity and Figure 7B illustrates female shearing cavity.

[0115] Figure 8 illustrates assembled shearing cavity.

[0116] Figure 8 illustrates shearing plate assembly.

[0117] Figure 9 illustrates schematic representation of spacer.

[0118] Figure 10 illustrates exemplary shapes of cavities or pockets in male and female shearing cavity.

[0119] Figure 11 illustrates a graph showing size of nanobubbles generated in one of the embodiments.

[0120] Figure 12 shows the first module having a fluid inlet and a port for infusing gas / air.

[0121] Figure 13 shows the first module with a baffle jet.

[0122] Figure 14 shows an enlarged view of the baffle jet as well as the port for piping in gas / air

[0123] Figure 15 shows the exterior view of the completely assembled nanobubble generator according to one embodiment.

[0124] Figure 16 shows the cross-sectional view of the nanobubble generator according to another embodiment.

[0125] Figure 17 shows the cross-sectional view of the prototype model of the nanobubble generator.

[0126] Figure 18 shows the cross-sectional view of the four modules comprising the generator. Figure 19 shows exploded cross-sectional view of the generator.

[0127] Figure 20 shows exploded exterior view of the generator.

[0128] Figure 21 shows exterior view of the generator and static wireframe model.

[0129] Figure 22 illustrates a graph showing size-distribution of the nanobubbles generated by nanobubble generator according to one embodiment.

[0130] Figure 23 shows external view of the nanobubble generator (1) connected to a fluid pump (2) according to still another embodiment.

[0131] Figure 24 illustrates a Membrane diffuser (03) with a gas inlet at one end and capped at the opposite end.

[0132] Figure 25 shows external view of the nanobubble generator (01) with multiple membrane diffusers (03).

[0133] Figure 26 shows sectional view of the nanobubble generator (01) with multiple membrane diffusers (03).

[0134] Figure 27 shows exploded view of nanobubble generator (01).

[0135] Figure 28 illustrates a graph depicting the size distribution of nanobubbles made by the nanobubble generator (01).

[0136] Figure 29 shows a representative membrane element (06) in terms of shape and dimensions.

[0137] Figure 30 illustrates schematic representation of preparation method for nanobubble infused water as per one or more systems of the present invention.

[0138] DESCRIPTION OF THE INVENTION

[0139] While embodiments are described in this disclosure by way of description below, figures and reference numerals indicated therein, those skilled in the art will recognize that the embodiments are not limited to the description below or figures described. It should be understood that the figures and detailed description thereto are not intended to limit embodiments to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope as defined by the appended claims. The headings used in this disclosure are for organizational purposes only and are not meant to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (in other words, the term “may” is intended to mean “having the potential to”) instead of in a mandatory sense (as in “must”). Similarly, the terms “include”, “including”, and “includes” mean “including, but not limited to” and the terms “comprises”, “comprising” mean that other additional components or features are also present in addition to what has been described.

[0140] Generally, a device for generating nanobubbles refers to a device for generating and providing nanobubbles having various sizes such as less than 1 pm, preferably about 1 to 500 nm. The generated nanobubbles may have uniform size and are in high concentration.

[0141] The terms “fluid” and “liquid” have been used interchangeably in the description and mean that a substance that can flow.

[0142] The expression “free fluid” in the description refers to fluid which is present in at least one chamber of system for generating nanobubbles which is not being subjected to shear force by one or more shearing plates in the assembly of shearing plates. Accordingly, expression “free flow of fluid” in the description refers to unhindered flow of aforementioned “free fluid” in at least one chamber of system for generating nanobubbles.

[0143] The expression “optimal shear force” in the description refers to value or range of shear force which is sufficient for reducing size of bubbles in fluid or liquid to generate nanobubbles in fluid of size less than 1 pm. It is known the field that generation of nanobubbles using high shear forces may result in inefficient bubble formation with low percentage retention of at least one gas in the nanobubbles as generated nanobubbles may recombine to form gas molecules at elevated rates of high shear forces, as well as undesired aggregation or combination of nanobubbles into larger microbubbles or release of the gas from the fluid mixture. Further, generation of nanobubbles using very low shear forces may not generate nanobubbles at all from bubbles of large size.

[0144] The term “gas” in the description means that a substance that is in a gaseous, or vaporous, state of matter.

[0145] The term “beverage” in the description means that any potable fluid or liquid, which may comprise water, tea, coffee, beer, milk.

[0146] The expression “optimal levels of dissolved gas” in the description refers to dissolved level of gas in liquid or fluid at a concentration of 05 ppm or higher. The “pump” in the description may be a centrifugal pump comprising one or more impellers and may apply a negative pressure in one or more of modules or chambers of the nanobubble generators described herein, producing a negative pressure within the nanobubble generators. The negative pressure may cooperate with the fluid flowing across the one or more of modules or chambers of the nanobubble generators to facilitate nanobubble production. The negative pressure inside the nanobubble generators may draw the gas into the solution. In some embodiments, the negative pressure may enable formation of stable nanobubbles having an expanded size, facilitating bubble formation, and the bubbles may shrink to a more stable nanobubble size when exposed to the higher pressure.

[0147] The present invention relates to systems, tools, devices, and methods for generating nanobubbles, offering a range of innovations to address limitations in current technologies. It provides nanobubble generators that utilize a combination of cavitation and shearing forces to form nanobubbles in a continuous fluid medium efficiently. These generators are capable of producing high concentrations of stable, durable nanobubbles — lasting in the medium for at least three months — within an outflowing fluid per cycle. The invention enables the production of nanobubbles predominantly less than 1 pm, preferably within the 1 to 500 nm, more preferably 100 to 200 nm diameter range and average or mean bubble diameter in range of 50-200 nm, preferably 200 nm, with uniform size distribution, and without the use of chemical additives. Additionally, the nanobubble generators are designed to be energy-efficient, lightweight, and portable, providing a versatile and effective solution for various industrial and commercial applications.

[0148] As mentioned, the potential applications of nanobubble technology are enormous — but they can only be realized once the shortcomings of existing generators are overcome. To boost yield, consistency and energy efficiency while reducing cost, the inventors have combined cavitation hydrodynamics (which produces microbubbles) with shearing forces to generate high concentrations of uniformly sized nanobubbles. In the preferred embodiment, the shear plates in the assembly of shear plates are patterned with cavities of various shapes, promoting the controlled breakup of cavitation bubbles into ultrafine, uniform nanobubbles. Nanobubbles are formed by hydrodynamic cavitation in liquids via pressure differentials: as liquid in a pump experiences low pressure, vapor-filled cavities form; when pressure recovers, these cavities collapse, imploding at their weakest points and yielding nanobubbles.

[0149] Although hydrodynamic cavitation is favoured for its simplicity and low cost, it typically produces a broad size distribution. Other generation mechanisms — shear flow, nucleation, and shockwave-induced collapse — can be used alone or in combination to refine bubble size. Common implementations include injecting low-pressure gas into liquids, using Venturi devices (in full- or side-stream configurations), or dissolving gas under pressure and expelling it through nanoporous diffusers.

[0150] By integrating these principles, the present invention delivers a more consistent, energy-efficient route to stable, uniformly sized nanobubbles.

[0151] Conventionally, nanobubbles are generated in fluids using various types of apparatus, for example:

[0152] • Venturi-type generators, which rely on the Venturi principle

[0153] • Swirl-type generators, which create bubbles through fluid swirling

[0154] • Mixer-type generators, which use mechanical mixing

[0155] • Cavitation-type generators, which exploit vapor cavity collapse

[0156] • Pressurized-dissolution-type generators, which dissolve gas under pressure and release it to form bubbles

[0157] Each type employs a different mechanism to introduce and disperse gas into the liquid.

[0158] However, each type of micro- or nanobubble generator known in the art is limited in its ability to produce nanobubbles with high concentration (density), uniform size distribution, and extended lifespan. The present invention addresses these shortcomings by seamlessly integrating multiple generation principles — specifically, swirling, static mixing, and Venturi effects — to yield nanobubbles of uniform size, higher density, and improved longevity in a cost-effective manner.

[0159] In this hybrid system, the swirl mechanism efficiently entrains air into the liquid, the static mixer refines bubble dispersion, and the Venturi stage optimizes nanobubble formation by generating a precise low-pressure region. A novel swirling baffle jet further enhances performance by directing flow of fluid into the Venturi’s low-pressure zone, significantly boosting nanobubble formation efficiency and offering a level of sophistication absent in existing generators.

[0160] The invention also combines hydrodynamic cavitation with shearing forces: microbubbles formed by cavitation are forced through high-pressure shearing cavities, where they disintegrate into ultrafine nanobubbles.

[0161] The present invention also provides a method for preparation of nanobubble infused beverage or fluid by using one or more systems of the present invention. In an exemplary embodiment of the invention, the beverage or fluid being infused with nanobubbles is water.

[0162] The method may comprise ozonation of fluid for instance water at levels of about 0.1 to 1 ppm, preferably 0.4 to 0.6 ppm. The step of ozonation may be followed by subjecting ozonised fluid to at least one pressure sand filter and / or at least one activated carbon filter to obtain initial filtered water which may further be subjected to at least one pre-RO filter, at least one RO system, at least one UV system optionally treating with salts of one or more alkali metals or alkaline earth metals to obtain treated water. The treated water may optionally be stored in a tank before or after being laden with nanobubbles by one or more systems of the present invention. The treated water may optionally be passed through at least one chiller unit for maintaining suitable temperature of water. The nanobubbles infused water may be passed through one or more filter(s) of size varying from 0.1 micron to 0.99 microns to obtain filtered nanobubbles infused water. In an optional step, the filtered nanobubbles infused water may further be treated by at least one ozonation unit.

[0163] The RO and / or UV-treated water is pumped from a reservoir through a chiller unit at a constant flow-rate, preferably at 10 to 50 cubic metres per hour, more preferably at about 30 cubic metres per hour. The chiller unit helps cool the circulating water to below 10°G preferably between 1°C and 5°C The chilled water is allowed to enter from least one inlet port for fluid of at least one nanobubble generator which also receives at least one gas, for instance ozone, oxygen, carbon dioxide etc. from at least one inlet other than the inlet for fluid.

[0164] The flow rate of fluid into the nanobubble generators is maintained at about 70 to 110 LPM, preferably 90 LPM. The flow rate of at least one gas into the nanobubble generators is maintained at about 1 to 50 LPM, preferably 5 to 10 LPM. Nanobubbles of at least one gas are generated within the nanobubble generators and exit through at least one outlet. Multiple nanobubble generators can be connected either in series or in parallel, with their outlets configured to recirculate the nanobubble-enriched water back into the generators. Samples of fluid laden with nanobubbles are periodically taken to monitor levels of at least one gas therein. The method of the present invention is capable of generating nanobubbles in a fluid at concentration of about 10 ppm or higher, preferably 50 ppm or higher.

[0165] The nanobubbles generated by systems, devices and methods of present invention find applications in food industry. The nanobubbles can enhance food processing, safety, and even create new food products. The nanobubbles can reduce contamination by removing contaminants and pathogens from food and water, leading to improved food safety. They can improve water quality by treatment of water and / or waste-water and reduce contaminants in post-harvest processing. They can enhance effectiveness of Clean-in-Place (C1P) processes, improve biofilm removal and reduce need for harsh chemicals thereby aiding in water treatment. Nanobubbles can improve water quality, making it suitable for reuse in food processing. Nanobubbles can also be used to improve food texture, viscosity, and even extract valuable components from food. Nanobubbles can reduce viscosity of high protein dairy streams and improve solubility of milk powders. Nanobubbles can alter texture of various food products, like foams and gels, by controlling gas diffusion. Nanobubbles can be used for targeted nutrient delivery in foods; as fat replacers in baked goods; in food packaging to provide antimicrobial protection; and in developing food systems for long-duration space missions.

[0166] Nanobubbles also finds applications in field of aquaculture by maintaining clean and oxygen-rich environment without added chemicals, improving feed conversion and reducing stress. This supports optimal conditions for growth of fish, shrimp and / or other aquatic life, nutrition, and disease resistance, reducing reliance on medicinal treatments. In similar manner, the nanobubbles also find applications in field of agriculture by enhancing water quality, promoting plant growth, and reducing the need for chemical inputs. Nanobubbles infused water increase oxygen levels thereby improving nutrient absorption, and help control pathogens and algae, ultimately leading to healthier crops and reduced environmental impact. Nanobubbles further find applications in medical field, for instance, through their combination with ultrasound, providing clearer and superior imaging than microbubbles do in disease diagnosis. Nanobubbles can enhance therapeutic efficacy and targeted drug delivery, controlled release, enhanced drug penetration, improved stability and biodegradability, especially when combined with ultrasound.

[0167] Environmental applications of nanobubbles are but not limited to enhancing water purification, improving soil remediation and boosting agricultural productivity.

[0168] The embodiments of the present invention are described below by way of illustrative examples, which are provided solely to clarify its principles and are not intended to limit its scope.

[0169] Several embodiments of the invention are described below. These are to be construed as non-limiting. A person skilled in the field will realize that it is possible to make other variants of the invention. However, it is emphasized that such modifications will fall under the ambit of the invention and are covered by it so long as they utilize the same concept.

[0170] The nanobubble generators (systems and devices) and methods described herein involve the generation of nanobubbles through a combination of controlled cavitation and shearing method occurring in a two-stage process. In the primary stage (B), microbubbles are formed, ranging in size from 1pm to 100pm in diameter. Subsequently, in the second stage (C), the microbubbles -laden fluid is subjected to high pressure thereby inducing strong shearing stress (Figure 1) and the microbubbles are transformed into nanobubbles (D) of less than 1pm diameter.

[0171] The generator comprises a first chamber having a proximal end having a fluid inlet and a distal end fluidically connected to a second chamber (Figure 2). The first chamber contains a pump (1) which transports fluid from the liquid source and it further contains a gas inlet (2) which admits gas into the said chamber. The second chamber comprises of an assembly of shearing plates (3), as shown in Figure 3. The shearing plate assembly comprises of a plurality of alternating male (10) and female shearing plates (20), as depicted in Figure 5 and Figure 6. Male and female shearing plates are circular plates with octahedral cavities or pockets in them. The cavities or pockets can be of different shapes, as depicted in Figure 10. The shapes of the cavities or pockets can be, not limiting to, circular, rectangular, and polygonal with at least 3 sides. Spacers (5) are provided to keep the free fluid flowing into the shearing plate assembly for sufficient shear force creation. The optimal number of shearing plate assemblies is placed inside the nanobubble mixer tube with the number of spacers as depicted in Figure 4. The exemplary shearing plate assembly (4) can have multiple male and female shearing plates arranged within an outer tube (6). Microbubbles flow into the inlet (E) of the shearing plate assembly (4) and nanobubbles flow out of the outlet (D). Male and female shearing plates are designed to create shear force by generating tangential fluid force on the fluid element through the octahedral cavities or pockets in the shearing plates.

[0172] The liquid circulating pump could be any type negative, positive or submersible pump. Gas is injected close to the pump suction side to facilitate mixing the gas into a flowing liquid medium. Nanobubbles are generated with at least one type of gas such as oxygen, ozone, nitrogen, etc. Gas is introduced at the pump inlet due to the negative pressure of the pump gas mixed with water before moving to the pump impeller.

[0173] In the first stage (B), cavitation is generated where the liquid pressure equals or less than the vapor pressure at the pump. Microbubbles are generated using controlled cavitation with a liquid-gas mixture. The gas and liquid mixture maintained is about 2 to 12 %, preferably about 3% to generate the microbubble by controlling the cavitation. In the present invention, purified clean RO water (SKF Elixer India Private Limited) is used to generate nanobubbles. A negative pressure of about -0.10 to -0.50 bar, preferably- 0.133 bar is maintained at the inlet, facilitating the intake of the liquid, which is then expelled outward under high pressure. The flow rate of the fluid into the pump is maintained at about 90 LPM (Litre per minute).

[0174] In the second stage (C), the cavitation microbubbles generated at first stage are fed to the nanobubble mixer / generator with a liquid velocity of about 3.8 m / s and a liquid pressure of about 1 to 5 bar, preferably about 3 bar. The microbubble-containing liquid enters the shearing assembly, which consists of male and female shearing plates as depicted in Figure 7 A, Figure 7B and Figure 8. As the liquid passes through the shearing plate, it enters the shearing cavities or pockets and creates a zigzag motion due to the combination of male and female shearing plates. Small cavity pockets with various shapes comprising of circular, rectangular, polygonal, etc. are strategically designed to create a complex liquid flow path, introducing additional opposing forces to the liquid. When the fluid flows inside the octahedral cavities or pockets, it offers more resistance, generating a high shear stress of about 60 to 100 Pa, preferably about 70 to 80 Pa, more preferably about 79 Pa on the cavity or pocket wall. Microbubbles are converted into nanobubbles due to the action of shear force on them. Multiple shearing assemblies are placed inside the nanobubble mixer tube, and a spacer (Figure 9) is provided between the shearing assemblies for sufficient fluid flow to the shearing component.

[0175] The nanobubble containing fluid is collected and analyzed using Nanoparticle tracking analyzer where incoming LASER beam is scattered by the nanobubble and its Brownian movement is captured by real-time camera. The average bubble size at the outlet of the nanobubble generator is less than 200 nm in diameter (Figure 11). The bubble concentration per unit volume is about 675 million per ml. The zeta potential (Mean) of nanobubbles were calculated to be about - 44.3 mV.

[0176] In an aspect, the present invention provides other energy-efficient nanobubble generators.

[0177] The nanobubble generators of the present invention are capable of providing a high-yield of nanobubbles in the out-flowing fluid. The nanobubbles produced by the nanobubble generators of the present invention are chemical and additive -free. The nanobubble generators of the present invention are light and portable.

[0178] The present invention further provides source for making more durable nanobubbles that can last in the medium without collapsing for more than a month. The nanobubble generators of the present invention are also capable of producing a greater density of nanobubbles with uniform size-distribution. The nanobubbles generated by the nanobubble generators of the present invention are of very narrow bubble size- distribution.

[0179] The potential applications of nanobubble technology are enormous and can be realized only if the deficiencies of the presently prevailing nanobubble generators are rectified. In order to increase yield, consistency, efficiency and reduce costs, the inventors of the present invention have integrated mainly cavitation hydrodynamics with at least one baffle jet to obtain predominantly uniform nanobubbles consistently with the novel-design bubble generator. In an embodiment the nanobubble generator of the present invention has a combination of at least one baffle jet and at least one cavitation -inducing component to generate nanobubbles predominantly having an average 200 nm or less diameter. The generator comprises of multiple components that are in fluidic communication with each other and can be assembled together in any sequence to generate nanobubbles. In the preferred embodiment of the present invention, the liquid and gas inlet component has a baffle jet leading on to baffle, spiral and Venturi assemblies.

[0180] The design of the nanobubble generator of the present invention integrates multiple modules seamlessly, each fluidically connected serially to provide synergistic output. The nanobubble generator of the present invention comprises a first module (021) comprising a fluidic chamber (020) having a proximal end and a distal end, a fluid inlet (024) disposed at said proximal end, and said distal end in fluid communication with a second chamber / module (022). A gas inlet port (025) is disposed perpendicular to the fluid inlet (024) of said first chamber / module (021) and is directed to deliver the gas / air at the distal end of said first chamber / module into the fluid entering the second chamber / module (022). The fluid inlet widens immediately before the gas inlet port enters said first chamber / module. The remaining chamber / module has baffles (026) on the walls of module to induce a flow pattern to the egressing fluid. Figure 12 shows the first module having a fluid inlet and a port for infusing gas / air. Figure 13 shows the first module with a baffle jet. Figure 14 shows an enlarged view of the baffle jet as well as the port for piping in gas / air. Figure 15 shows the exterior view of the completely assembled nanobubble generator.

[0181] The proximal end of the second chamber / module abutting from the first chamber / module expands and sports a baffle system on its inner walls till it converges at the distal end into a third chamber / module (022). The third chamber / module has a smooth outer wall and has a spiraled-cone (027) at its core which induces spiral flow of the fluid along the chamber / module. Liquid (or a mixture of liquid and gas) is introduced tangentially into the chamber, creating swirl flow. Negative pressure along the chamber's centreline which is embedded within the baffle structure sucks in air from the top, and strong shear flows convert it into fine bubbles. The pressure along this negative chamber is about -0.15 bar which is sufficient to suck in air from the atmosphere. Figure 16 shows the cross-sectional view of the nanobubble generator. Figure 17 shows the cross-sectional view of the prototype model of the nanobubble generator. Figure 18 shows the cross-sectional view of the four modules comprising the generator.

[0182] The baffle structure in the second chamber / module (022) further increases the necessary turbulent energy required to create the cavitation bubbles. When turbulent kinetic energy increases bubble size decreases. The third chamber / module (030) has spiral grooves (029) along the surface of the convergent cone which further acts to increase the turbulence and also acts to provide the necessary shear to reduce the size of bubbles. The structure of these grooves can be contoured to circular, rectangular, or any other polygonal form, in order to create the desired turbulence.

[0183] The third chamber / module (030) is fluidically connected to a fourth chamber / module (040) and third chamber / module (030) and / or fourth chamber / module (040) is configured for a Venturi effect. Fourth module has an inlet at proximal end to receive fluid from third module and may consists of Venturi tube or any other suitable Venturi design to generate negative pressure and further generate nanobubbles in incremental manner. As the two-phase flow accelerates through the throat of the Venturi tube (030), pressure changes rapidly, resulting in the formation of nanobubbles. The fourth chamber / module has at its distal end (028), a fluid outlet which empties into a collection vessel. The fluid-laden with nanobubbles is collected in this vessel and dispensed. Figure 19 shows exploded cross-sectional view of the generator. Figure 20 shows exploded exterior view of the generator. Figure 21 shows exterior view of the generator and static wireframe model.

[0184] The nanobubble generator described in this invention is able to consistently produce nanobubbles with sizes averaging less than or equal to 200 nm. This results from a judicious balance of the swirling, mixing, and Venturi components. The hybrid approach integrating static mixing, swirling, and pressurized dissolution methods subject the fluid-gas mix to requisite flow-dynamics and shear forces to ensure that the generated nanobubbles meet strict size ranges for optimal performance in various applications. The flow rate of the fluid from the pump to the nanobubble mixer is maintained at about 90 LPM (Litres per minute). For testing purposes water from an RO source was used (SKF Elixir India Private Ltd.) The nanobubble generators can be operated directly using atmospheric air alone or with gases injected into the system. Gases may be pumped in at about 8.0 LPM or the system can suck about 1.5 LPM air from the atmosphere.

[0185] Samples taken out from the collection vessel are subjected to nanoparticle tracking analysis wherein a LASER is aimed at the sample. Brownian movement of the nanobubbles in the fluid scatter the LASER which is continuously registered by a camera. The density of the nanobubbles in the sample and their sizes can be read out from the results. The results indicate average bubble diameter size in range of 50 to 200 nm, preferably 200 nm. The bubble concentration per unit volume is about 448 million per ml.

[0186] The surface charge of the nanobubbles was also analysed. The sample containing the nanobubbles is subjected to an electrical field and movement of the nanobubbles based on their surface charge is registered by the phenomenon of electrophoretic light scatter. The zeta potential of nanobubbles was found to be about -18.7 mV.

[0187] The nanobubble generator requires less energy to pump air / gas into the system, owing to the positioning of the outlet strategically near the throat region of the converging-diverging area with lower pressure. Figure 22 is graph showing the sizedistribution of the nanobubbles generated by the nanobubble generator of the present invention.

[0188] It will be appreciated that all of the components of the above-described nanobubble generator modules may be simply connected together for instance by thread and screw mechanism, or by other pipe-connecting techniques, being capable of disconnection and reconnection as required. There can be a plurality of nanobubble generators connected in series or parallel to increase the eventual output. It is also possible to enrich nanobubble production by recirculating the outflowing fluid back into the fluid inlet at the first module itself.

[0189] In another aspect, the inventors of the present invention have designed more energy-efficient nanobubble generators that perfuse gas under pressure through ceramic nanoporous membranes into the surrounding fluid medium. Preferably, these diffusers are sealed nanoporous ceramic chambers with a single inlet that receives gas under pressure, allowing it to perfuse through the ceramic nanopores into the surrounding fluid, thereby creating nanobubbles. The nanobubble generator (001) of the present invention comprises a chamber having a proximal end (01) and a distal end (02) wherein the proximal end receives an inlet port (Figure 23, Figure 25). A fluid is allowed to enter said chamber through said inlet port and exit through a port on the distal end. The flow of the fluid is substantially linear. Placed in the chamber so as to intercept the fluid flow substantially at right angles is at least one membrane-based gas diffuser (03).

[0190] In an embodiment, a plurality of such diffusers (03) may be placed in the flowstream at substantially right angles to the direction of fluid -flow.

[0191] In a preferred embodiment, each diffuser (03) comprises of an elongated chamber composed of a porous material having two opposing ends. The first end (04) accommodates a means for gas-injection into said elongated chamber while the second end (05) is sealed (Figure 24, Figure 25 and Figure 26). The plurality of gas diffuser units (03) may be connected serially or individually to a gas source from where the gas can be pumped under pressure.

[0192] When gas, such as air is injected under pressure into the gas diffuser (03), it escapes through the nanoporous chamber walls into the surrounding fluid stream. The nanometre-sized bubbles formed at the diffuser surface-fluid medium interface are sheared off into the medium owing to the fluid flow and are collected at the outlet port of the nanobubble generator.

[0193] In a preferred embodiment of the invention, the gas diffusers (03) comprise of an outer porous membrane (06) that is constructed from a ceramic base material, coated with a-Al203(alumina) (Figure 24, Figure 29). The coating is of a thickness which may vary between about 1 and 10 microns. Through experimental analysis, the inventors derived at the optimal combination that provides the necessary properties for effective gas transfer and bubble generation. The membranes may have the following specific dimensions: length (L) ranging from about 100 to 1200 mm; a preferred length of about 500 mm and a most-preferred length of about 140 mm. Membranes can be of single channel geometry or plurality of channels ranging from about 1 to 160. With a single channel, length ranging from about 10 to 40 mm, while the optimal thickness of the membrane is achieved with an outer diameter (07) of from about 1 to 100 mm and preferably 10 mm and an inner diameter (08) of from about 2 to 100 mm, preferably about 7 mm. The membranes (06) are designed with a pore-size of about 70 nm that is critical to generation of nanobubbles of a preferred size and quantity. Larger pore size tends to generate larger bubbles and vice-versa. These single-channel membranes of about 140 mm length and an outer diameter of about 10 mm has a total surface area of around 0.0043 m2. Thus, if five membrane diffusers are deployed, the total surface area of all membranes combined equals about 0.0215 m2. The surface area available for gas -liquid interaction facilitates efficient gas exchange and bubble formation.

[0194] Gas is injected at a pressure sufficiently high to create nanobubbles but not high enough that the membrane is disrupted. Preferably gas pressure ranges are maintained from about 2 to 3 Bar, and the most-preferred pressure is about 3 Bar forming gas cavities at the interface between the liquid and gas media through the nanopores. Pressures above the preferred range mentioned tend to enlarge the pore sizes in the membrane and damage the membrane structure increasing the bubble size. Liquid flow can be maintained at a range of about 5 to 30 m3 / h, inducing the gas bubble to shear off from the membrane surface, creating bulk nanobubbles in the liquid medium. A higher flow rate is not preferred as it can lead to smaller bubbles, affecting overall bubble quality and size-distribution of the nanobubbles. The fluid flow rate was optimised at about 7.28 m3 / h which is equivalent to about 2 m / s through the membrane elements,

[0195] Nanoparticle Tracking Analysis (NTA) is the most effective and widely used method for measuring nanobubbles. It is an optical technique that measures the size and concentration of nanobubbles by tracking their Brownian motion. This is achieved by directing a laser beam into the nanobubble fluid chamber. Light scattered by the nanobubbles is recorded using a high-resolution camera to analyze the size and concentration of the nanobubbles in the fluid. The predominant size-range of nanobubbles generated by the instant generator was between 150 and 200 nm with a mean diameter of 193.3 nm. In terms of density, the samples measured a total concentration of 414 million per millilitre.

[0196] Surface charge of the nanobubble was studied in terms of their Zeta potential. Zeta potential is measured by the combination of Dynamic Light Scattering (DLS) with Electrophoretic Light Scattering (ELS) techniques. From one batch of the experiment, the results indicated that the generated nanobubbles had a zeta potential of -21.2 mV. The present invention thus provides an efficient method of generating bulk nanobubbles with even-size distribution. The nanobubbles produced by the nanobubble generator of the present invention are chemical and additive-free thereby minimizing environmental impact while being amenable to a range of applications.

[0197] The present invention provides oxygen enriched beverages and methods of preparing oxygen beverages. The present invention also provides devices, apparatus and systems for preparing oxygen beverages.

[0198] The oxygen beverages of the present invention comprise high dissolved oxygen (DO) concentration. The high dissolved oxygen concentration in the beverages is continuously maintained even during storage or distribution process.

[0199] The present invention achieves elevated DO levels in beverages by entrapping oxygen within nanobubbles. The process involves creating oxygen nanobubbles and optimizing the saturation of water or beverages with these nanobubbles under ambient conditions.

[0200] The present invention provides an efficient alternative approach for infusing oxygen into beverages, such as water, in the form of nanobubbles. It also establishes optimal conditions to achieve and sustain supersaturated levels of oxygen in solution.

[0201] The present invention includes a storage reservoir for RO- and UV-treated water, from which water is circulated through a chiller unit to reduce its temperature to between 1°C and 5°C. The chilled water is then passed through one or more nanobubble generators, as described above.

[0202] Oxygen gas pumped into the nanobubble generator(s) is converted into oxygen nanobubbles. At lower temperatures, these nanobubbles achieve greater incorporation into the circulating water, resulting in higher DO levels. The oxygen nanobubble - enriched water is recirculated through the chiller-nanobubble generator system multiple times until the desired DO levels are achieved. Once the desired DO level is attained, the nanobubble-enriched water is drawn from the generator's outlet. A schematic representation of a method for preparation for nanobubble infused water as per one or more systems of the present invention is provided in Figure 30. The RO and UV-treated water is pumped from the reservoir through the chiller unit at a constant flow-rate, preferably at around 30 cubic metres per hour. A chiller unit helps cool the circulating water to below 10°Q preferably between 1°C and 5°C The chilled water is allowed to enter the inlet port of at least one nanobubble generator which receives oxygen from a second inlet.

[0203] The flow rate of fluid into the nanobubble generators is maintained at 70-110 LPM, preferably 90 LPM. The flow rate of oxygen into the nanobubble generators is maintained at 5 to 10 LPM. Oxygen nanobubbles are generated within the nanobubble generator and exit through its outlet. Multiple nanobubble generators can be connected either in series or in parallel, with their outlets configured to recirculate the nanobubble-enriched water back into the generators.

[0204] Water samples are periodically taken to monitor DO levels. Compared to the 5-8 ppm DO levels typically achieved by conventional methods, the present invention can elevate DO levels to 50 ppm or higher.

[0205] Stability of nanobubbles in water over time:

[0206] Thus, the present invention provides reliable, scalable methods for producing and sustaining high DO levels in drinking water or other beverages, making it suitable for a variety of applications where oxygenated water is desired. The nanobubble generator described in these applications offers high efficiency, reduced cost, improved nanobubble yield, enhanced quality, and greater durability.

[0207] Although the subject matter has been described herein with reference to certain preferred embodiments thereof, other embodiments are possible. For illustrative purpose, the systems, devices and methods of invention have been shown in exemplary figures and disclosure above. However, those skilled in the art would appreciate that the present invention is not limited to the disclosure of the exemplary embodiments described above.

[0208] It will be obvious to those skilled in the art to make various changes, modifications and alterations to the invention described herein. To the extent that these various changes, modifications and alteration do not depart from scope of the present invention, they are intended to be encompassed therein.

Claims

We claim:

1. A system for generating nanobubbles comprising: at least one first chamber (1) for generating microbubbles in mixture of fluid and at least one gas for preparing microbubbles-laden fluid by hydrodynamic cavitation; and at least one second chamber (7) for transforming microbubbles generated by the first chamber to nanobubbles by shearing force, i) wherein the first chamber (1) has a proximal end comprising at least one inlet for fluid, at least one inlet for gas (2) and at least one pump , and a distal end for fluidically connecting the first chamber to the second chamber; and ii) wherein the second chamber (7) comprises assembly of shearing plates (3) arranged in at least one nanobubble mixer tube (6).

2. The system as claimed in claim 1, wherein the assembly of shearing plates comprises plurality of alternating male (10) and female (20) shearing plates.

3. The system as claimed in claim 2, wherein the male (10) and female (20) shearing plates comprises cavities or pockets therein which are circular or polygonal in shape.

4. The system as claimed in claim 2 or 3, wherein the assembly of shearing plates (3) further comprises plurality of spacers (5) for maintaining free flow of fluid thereby creating sufficient shear force.

5. The system as claimed in any one of claims 1 to 4, wherein the device generates nanobubbles in a continuous fluid medium by integrating hydro dynamic cavitation and shearing force in a two-stage process.

6. The system as claimed in any one of claims 1 to 5, wherein the pump maintains flow rate of the fluid at about 70 to 110 LPM (Litre per minute), preferably about 90 LPM.

7. A method of generating nanobubbles in a fluid by integrating hydrodynamic cavitation and shearing force in a two-stage process, comprising a first stage and a second stage wherein:i] in the first stage microbubbles are formed in a mixture of the fluid and at least one gas by generating cavitation to obtain microbubbles-laden fluid in at least one first chamber; and ii] in the second stage, the microbubbles obtained in i] are transformed into nanobubbles by subjecting the microbubbles-laden fluid to high pressure thereby inducing high shearing stress of about 60 to 100 Pa, preferably about 79 Pa in assembly of shearing plates in at least one second chamber to obtain nanobubbles.

8. The method as claimed in claim 7, wherein the cavitation is generated in the first stage by maintaining fluid pressure equal to or less than vapor pressure.

9. The method as claimed in claim 7 or 8, wherein the microbubbles are generated in the first stage by controlled cavitation with a liquid-gas mixture maintained at about 2 to 12 %, preferably about 3% and a negative pressure of about -0.10 to -0.50 bar maintained at inlet of at least one first chamber of a system generating nanobubbles.

10. The method as claimed in any one of claims 7 to 9, wherein a pump in at least one first chamber of a system generating nanobubbles maintains flow rate of fluid at about 70 to 110 Litre per minute (LPM), preferably about 90 LPM.

11. The method as claimed in any one of claims 7 to 10, wherein the second stage comprises feeding the microbubbles generated in the first stage to a nanobubble generator in at least one second chamber of a system generating nanobubbles with a liquid velocity of about 2 to 5 m / s and a liquid pressure of about 1 to 5 bar, preferably about 3 bar.

12. The method as claimed in any one of claims 7 to 11, wherein in the second stage microbubbles-laden fluid is subjected to high shear stress of about 60 to 100 Pa, preferably about 79 Pa on walls of one or more of cavities or pockets in the assembly of shearing plates thereby converting microbubbles into nanobubbles.

13. A system for generating nanobubbles comprising multiple modules in fluidic communication, assembled in any sequence, wherein the device comprises at least one first module (021), at least one second module (022), at least one third module (030) and at least one fourth module (040), wherein: i) the at least one first module (021) comprises a proximal end, a distal end, at least one inlet for fluid (024), at least one inlet for gas (025) positioned in a manner that it intercept flow of fluid from the at least one inlet for fluid (024) to deliver gas into the fluid entering the second module (022), plurality of baffle jets (026) positioned on walls of first module to induce flow pattern to egressing fluid, and wherein the distal end of first module is in fluid communication with proximal end of the second module; ii) the proximal end of the second module (022) abuts from the first module, expands and sports a baffle jet system on its inner walls until it converges at distal end wherein said distal end is in fluid communication with proximal end of the third module (030); hi) the third module comprises at least one spiraled convergent cone (027) at its core and the distal end of said third module is in fluid communication with proximal end (023) of the fourth module (040); iv) the fourth module comprises at its distal end (028) at least one fluid outlet which empties into a collection vessel; and wherein at least one of first module, second module, third module and fourth module are under negative pressure for generating cavitation.

14. The system as claimed in claim 13, wherein the inlet for fluid (024) in first module widens before the inlet of gas (025) enters said first module.

15. The system as claimed in claim 13 or 14, wherein the inlet for gas (025) is positioned substantially perpendicular to the at least one inlet for fluid (024).

16. The system as claimed in any one of claims 13 to 15, wherein the third module (030) comprises a smooth outer wall and the at least one spiraled convergent cone (027) at its core induces spiral flow of the fluid along the third module.

17. The system as claimed in any one of claims 13 to 16, wherein the third module comprises plurality of spiral grooves (029) along surface of the spiral convergent cone (027) for increasing turbulence and for providing optimal shear force to reduce size of bubbles.

18. The system as claimed in claim 17, wherein the spiral grooves (029) are contoured to at least one shape selected from circular, rectangular, or any other polygonal form to provide desired turbulence.

19. The system as claimed in any one of claims 13 to 18, wherein the third module (030) further comprises at least one Venturi tube.

20. The system as claimed in any one of claims 13 to 19, wherein the system combines at least one baffle jet and at least one additional component generating cavitation.

21. The system as claimed in any one of claims 13 to 19, wherein the system generates nanobubbles by integrating swirling, mixing, and Venturi effects by one or more baffle jet, spiral and Venturi components present in one or more of the first module, the second module, the third module and the fourth module.

22. A method of generating nanobubbles by a system comprising multiple modules in fluidic communication with each other, comprising: i) mixing of fluid and at least one gas by at least one first module to obtain mixture of fluid and gas; ii) introducing mixture of fluid and gas obtained in i) tangentially into at least one second module to create swirl flow; hi) creating cavitation bubbles in the mixture of fluid and gas introduced in the second module in ii) by at least one baffle jet of the at least one second module; iv) subjecting the cavitation bubbles obtained in hi) to shear force by plurality of spiral grooves along surface of convergent cone of at least one third module to obtain bubbles of reduced size;v) subjecting the bubbles of reduced size of iv) to Venturi effect by at least one Venturi tube of the third module and / or at least one fourth module to obtain fluid laden with nanobubbles; and vi) collecting the fluid laden with nanobubbles in v) by at least one fluid outlet of the fourth module.

23. The method as claimed in claim 22, wherein centerline of at least one second module embedded within the baffle structure is maintained at negative pressure of about - 0.1 to -0.50 bar, preferably about -0.15 bar.

24. The method as claimed in claim 22 or 23, wherein flow rate of the fluid through the multiple modules is maintained at about 70 to 110 LPM, preferably about 90 LPM.

25. A system (001) for generating nanobubbles wherein the system comprises a chamber having a proximal end (01) and a distal end (02) wherein the proximal end receives at least one inlet port such that a fluid enters said chamber through the inlet port and exits through at least one port on the distal end, and wherein the chamber comprises one or more membrane-based gas diffusers (03).

26. The system as claimed in claim 25, wherein the gas diffusers (03) are positioned in flow-stream in a manner to intercept direction of flow of fluid.

27. The system as claimed in any one of claim 26, wherein the gas diffusers (03) are positioned in flow-stream at substantially right angles to direction of flow of fluid.

28. The system as claimed in any one of claims 25 to 27, wherein each gas diffuser comprises at least one elongated chamber composed of porous material having two opposing ends a first end (04) and a second end (05), wherein the first end (04) accommodates a means for gas-injection into said elongated chamber while the second end (05) is sealed.

29. The system as claimed in any one of claim 25 to 28, wherein the one or more membrane-based gas diffusers (03) may be connected serially or individually to a gas source from where the gas is pumped under pressure.

30. The system as claimed in claim 30, wherein the coating of the gas diffusers (03) is of thickness between about 1 and 10 microns, preferably about 8 microns.

31. The system as claimed in any one of claim 25 to 30, wherein the gas diffusers (03) comprise at least one outer porous membrane (06) constructed from a ceramic base material and coated with a-Al203(alumina).

32. The system as claimed in claim 31, wherein the porous membrane (06) is of length from about 100 to 1200 mm; preferably of about 500 mm and more preferably of about 140 mm.

33. The system as claimed in any one of claim 31 to 32, wherein the porous membrane (06) comprises an outer diameter (07) of thickness of about 4 to 200 mm, preferably about 1 to 20 mm, more preferably about 10 mm and an inner diameter (08) of thickness of about 1 to 100 mm, preferably about 2 to 10 mm, more preferably about 7 mm.

34. The system as claimed in any one of claims 31 to 33, wherein the porous membrane (06) comprises one or more channels ranging from about 1 to 160.

35. The system as claimed in any one of claims 31 to 34, wherein the porous membrane (06) comprises pores of size of 1 pm or less, preferably about 1 to 500 nm, more preferably about 50 to 70 nm for generation of nanobubbles.

36. The system as claimed in any one of claims 25 to 35 wherein the system employs membrane-based diffusion and perfuses gas under pressure through ceramic nanoporous membranes into the surrounding fluid medium thereby generating nanobubbles.

37. A method of generating nanobubbles by membrane-based diffusion comprising:injecting mixture of a fluid and at least one gas under pressure into one or more membrane-based gas diffuser to obtain fluid laden with nanobubbles, wherein the membrane-based gas diffuser is of thickness between about 1 and 10 microns, preferably about 8 microns and is constructed from a ceramic base material and coated with a-Al203(alumina).

38. A system for generating nanobubbles, wherein the system comprises multiple systems for nanobubble generation as claimed in any one of claims 1 to 6, 13 to 21 and 25 to 36 connected in series, parallel, or a combination of series and parallel to generate large volumes of nanobubble-laden fluid.

39. A system of infusing a beverage or fluid with high concentration of at least one gas comprises using system as claimed in any one of claims 1 to 6, 13 to 21 and 25 to 36 connected in series, parallel, or a combination of series and parallel.

40. A method of infusing a beverage or fluid with high concentration of at least one gas wherein the method comprises converting at least one gas into nanobubbles using a system as claimed in any one of claims 1 to 6, 13 to 21 and 25 to 36 and infusing the obtained nanobubbles in the beverage or fluid at regulated temperature to get optimal levels of dissolved gas.

41. A method of preparation of water infused with nanobubbles of at least one gas comprising: a. optionally treating water prior to infusing nanobubbles by one or more system as claimed in any one of claims 1 to 6, 13 to 21 and 25 to 36 with ozone followed by passing through one or more filters of suitable pore size and / or treatment by salts of one or more alkali metals and / or alkaline earth metals to obtain treated water; b. generating and infusing nanobubbles in water or treated water of a) by system as claimed in any one of claims 1 to 6, 13 to 21 and 25 to 36 to obtain water infused with nanobubbles of at least one gas; and c. optionally treating water infused with nanobubbles of at least one gas of step b) with ozone followed by passing through one or more filters of suitable pore size.

42. A beverage or fluid infused with nanobubbles of at least one gas wherein the beverage has been infused with the nanobubbles by use of system as claimed in any one of claims 1 to 6, 13 to 21 and 25 to 36, system as claimed in any one of claims 38 and 39 and the method as claimed in any one of claims 7 to 12, 22 to 24 and 37.

43. Use of systems as claimed in any one of claims 1 to 6, 13 to 21 and 25 to 36, system as claimed in any one of claims 38 and 39 and the method as claimed in any one of claims 7 to 12, 22 to 24 and 37 for generating nanobubbles for food industry, agriculture, aquaculture, water treatment, medical field, wastewater treatment, surface cleaning, froth flotation, nanobubbles as an ultrasound contrast agent, therapeutic drug delivery, drag reduction, promotion of the physiological activity of living organisms, sterilization of bacteria, accelerated seed germination and improved blood oxygenation, detergent-free cleaning processes, tertiary oil recovery, foam fractionation, mineral flotation, food-processing, intracellular drug delivery, biomedical engineering, medicine, and environmental applications.

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