Nanobubbles are gas bubbles smaller than 200 nanometers that stay suspended in water for weeks instead of seconds. When charged with ozone, they deliver vastly improved water treatment compared to traditional ozonation because the smaller bubble size increases gas-to-water surface area, extends residual contact time, and disperses through Brownian motion instead of rising and bursting. In greenhouse and indoor agriculture, ozone nanobubbles inactivate root pathogens like Pythium, Phytophthora, and Fusarium, break down biofilm in irrigation lines, reduce chemical inputs, and add dissolved oxygen that supports root health. Peer-reviewed studies show ozone nanobubbles outperform conventional ozonation in disinfection efficacy, organic contaminant breakdown, and water reuse outcomes.
Water is the lifeblood of any agricultural system, and its quality plays a crucial role in determining the success of plant production. For greenhouse and indoor agricultural operations, the challenge of maintaining water quality has spurred interest in advanced technologies. One such innovation is nanobubble technology, which is now gaining traction in water treatment.
Nanobubbles, tiny gas bubbles less than 200 nanometers in diameter, have been found to possess unique properties that make them highly effective for various applications, including commercial water treatment. Unlike regular bubbles, nanobubbles exhibit long-term stability, meaning they can remain suspended in water for extended periods.
This property, along with their high surface-area-to-volume ratio, allows for enhanced mass transfer of gases like oxygen or ozone into the water. Nanobubbles can be produced through various methods, but in commercial applications, their production in bulk is usually achieved via either electrolysis, membranes, or cavitation (Favvas et al., 2021).
In agricultural water systems, nanobubbles can provide numerous benefits. Improved oxygenation and ozonation, for example, is possible because the high surface area of nanobubbles facilitates efficient gas transfer, allowing a greater quantity of gas to be dissolved in solution. This improves disinfection and aeration, promoting healthy plant root development and improving nutrient uptake. Biofilm reduction is another major advantage, as nanobubbles have been shown to help break down biofilms, which are thin layers of bacteria that accumulate on surfaces in water systems. Biofilms can harbor harmful pathogens and impede water flow, leading to disease and clogged emitters. Additionally, nanobubbles can act as micro-flocculants, helping to remove suspended solids and impurities in water, which ensures cleaner water for irrigation, reduces the risk of clogged systems, and enhances plant growth.
Ozone Nanobubbles: An Enhanced Water Treatment Solution
While nanobubbles themselves offer significant benefits in water treatment, they are most commonly employed with oxygen, which is a weak oxidant. The combination of ozone with nanobubble technology opens a new frontier by providing vastly improved water treatment, particularly in greenhouse and indoor agricultural production.
Ozone, a powerful oxidizing agent, has long been used for water treatment due to its ability to destroy a wide range of microorganisms, break down organic matter, and eliminate harmful contaminants. When introduced in the form of nanobubbles, ozone’s efficacy is significantly enhanced. The smaller size and stability of ozone nanobubbles, in comparison to traditional methods, allow for more effective diffusion and interaction with contaminants in water.
How Ozone Nanobubbles Outperform Conventional Ozonation
| Performance Factor | Conventional Ozonation | Ozone Nanobubbles |
|---|---|---|
| Bubble size | 1 mm and larger | Under 200 nm |
| Residual time in water | Seconds to minutes | Weeks to months |
| Gas transfer efficiency | Moderate | High (greater surface area) |
| Dispersal mechanism | Rises and bursts at surface | Brownian motion through solution |
| Pathogen contact opportunity | Limited by contact time | Extended across full water body |
| Best for deep tanks & ponds | Poor | Excellent |
| Biofilm penetration | Surface-level | Penetrates and disrupts |
In greenhouses and indoor agriculture, ozone nanobubbles deliver three primary outcomes. Pathogen control is the first, as ozone nanobubbles are highly effective at inactivating pathogens commonly found in greenhouse and indoor agriculture, including Pythium, Phytophthora, and Fusarium. The enhanced reactivity and residual times of ozone in nanobubble form ensure that these pathogens are eliminated more rapidly and thoroughly than with traditional ozone treatment. Reduced chemical usage is the second, since growers using ozone nanobubbles can cut their reliance on chemical disinfectants, which may leave harmful residues and negatively affect plant health. Ozone breaks down into oxygen, leaving no harmful byproducts. Finally, sustainable water reuse becomes possible in closed-loop systems common in greenhouse water treatment operations. Ozone nanobubbles can eliminate pathogens even under high-flow situations, oxidize organic contaminants, and reduce biofouling, allowing for the safe recirculation of irrigation water.
Scientific Backing for Greenhouse Production
Recent studies have delved into the specific benefits of ozone and nanobubble technology in agriculture. For instance, a study by Zhao et al. (2024) explored the use of ozone nanobubbles in hydroponically cultivated lettuce, demonstrating improved plant growth and reduced microbial contamination. Studies have investigated disinfection efficacy using ozone micro- and nano-bubbles in industries such as agriculture, wastewater, and drinking water, finding that small bubble sizes significantly improve the oxidative capacity of ozone and residual times. This leads to better microbial inactivation and contaminant removal compared to conventional ozonation methods (Seridou & Kalogerakis, 2021).
There is debate in the scientific literature regarding phytotoxicity resulting from ozonation of irrigation water for greenhouse crops. However, evidence suggests that direct application to plants can safely achieve pathogen control provided two conditions are met. First, intermittent dosage strategies must be used to minimize oxidative stress to the plants. Second, loss of iron and manganese as a result of ozonation must be accounted for in the fertigation strategy (Graham et al., 2011, 2012; Ishii et al., 2022; Martínez-Sánchez & Aguayo, 2019; Tahamolkonan et al., 2022; Tamaki et al., 2020; Zheng et al., 2020).
There is thus strong potential for combining the use of ozone and nanobubble technology in the treatment of irrigation water, providing powerful oxidation with improved residual times and offering a safe alternative to conventional pesticides. Because ozone decomposes into oxygen, crop health is further enhanced through high dissolved oxygen concentrations, and the introduction of chemical residues can be avoided entirely.
Scientific Backing for Other Industries
Ozone and nanobubbles have both been studied extensively for use in water treatment in the context of various industries, including wastewater, potable water, aquaculture, ground remediation, and other applications (Davidson et al., 2021; Gonçalves & Gagnon, 2011; Khan et al., 2020; Lei et al., 2023; Powell & Scolding, 2018; Spiliotopoulou et al., 2018).
Ozone is a powerful oxidant with excellent disinfection properties, and is oftentimes combined with catalysts that degrade it rapidly to produce hydroxyl radicals at high concentrations. Hydroxyl radicals are particularly useful for the removal of complex organic molecules or other contaminants that are resistant to other treatment methods. In the context of ponds, lagoons, and lakes, the short half-life of ozone is a limiting factor because diffusion of the gas throughout the entirety of water bodies can be limited by the residual time of the oxidant.
By employing the use of nanobubbles under 200 nanometers in size, a unique phenomenon occurs where the gas bubbles become negatively or non-buoyant, instead drifting randomly throughout the solution via Brownian motion. This unique property is particularly useful for diffusion across large, deep bodies of water. These dispersal mechanisms are attributed to a higher internal pressure of the gases inside the bubbles and a more negatively charged surface, overcoming the forces traditionally associated with bubbles in water (Khan et al., 2020).
While the underlying mechanisms are still debated, there is growing consensus that nanobubbles provide a significant advantage in various water treatment applications, especially with gases such as oxygen or ozone where solubility and dispersal are limiting factors.
Frequently Asked Questions
What are nanobubbles in water treatment?
Nanobubbles are gas bubbles smaller than 200 nanometers in diameter. Unlike normal bubbles that rise and burst within seconds, nanobubbles remain suspended in water for weeks or months due to their negatively charged surface and high internal pressure. This stability allows them to deliver gases like oxygen or ozone deep into water systems for extended treatment.
How are ozone nanobubbles different from regular ozonation?
Regular ozonation uses larger bubbles that quickly rise to the surface and burst, limiting how long ozone stays in contact with contaminants. Ozone nanobubbles stay suspended throughout the water body, dramatically extending contact time, improving gas transfer, and increasing disinfection efficacy. This produces better pathogen kill and organic contaminant breakdown at lower ozone doses.
Can ozone nanobubbles damage plants in greenhouse irrigation?
Direct application of ozonated water to plants can cause phytotoxicity if dosing is not controlled. However, peer-reviewed research shows that intermittent dosage strategies and fertigation adjustments that account for iron and manganese oxidation make ozone nanobubbles safe for greenhouse crops. Properly managed systems achieve pathogen control without harming plant health.
What pathogens do ozone nanobubbles control in greenhouses?
Ozone nanobubbles are highly effective against common greenhouse and hydroponic root pathogens, including Pythium, Phytophthora, and Fusarium. They also break down biofilm in drip lines and irrigation tanks, which prevents the recurring pathogen reservoirs that conventional chemical treatments often fail to eliminate.
How are nanobubbles produced commercially?
Commercial nanobubble production typically uses one of three methods: electrolysis, membrane diffusion, or cavitation. Cavitation systems are the most common for large-scale agricultural and industrial applications because they produce high volumes of stable nanobubbles continuously. Each method generates bubbles under 200 nanometers, which is what gives them their long residual time in water.
Do ozone nanobubbles work in ponds, lagoons, and large reservoirs?
Yes, and this is one of the strongest use cases. Conventional ozone treatment struggles in large or deep water bodies because ozone decays before it can diffuse through the full volume. Nanobubbles overcome this limit because their non-buoyant behavior allows them to spread through entire ponds and reservoirs via Brownian motion, treating water that would otherwise be unreachable.
Conclusion
Nanobubbles, and specifically ozone nanobubbles, represent a transformative approach to water treatment in agricultural and industrial applications. By leveraging the enhanced properties of these tiny bubbles, growers and operators can ensure superior water quality, reduce chemical inputs, improve water use efficiency, and improve productivity. The peer-reviewed research supporting this technology underscores its potential to revolutionize commercial water management in sustainable agriculture and general water treatment, making it a compelling solution for a future where water is becoming increasingly scarce.
References
| Author (Year) | Journal | Topic |
|---|---|---|
| Davidson et al. (2021) | Aquaculture | Ozone effects on Atlantic salmon in RAS |
| Favvas et al. (2021) | Curr. Opin. Colloid Interface Sci. | Bulk nanobubble generation methods |
| Gonçalves & Gagnon (2011) | Ozone: Sci. & Eng. | Ozone in recirculating aquaculture |
| Graham et al. (2011) | Scientia Horticulturae | Aqueous ozone via drip irrigation |
| Graham et al. (2012) | Scientia Horticulturae | Root zone ozone in hydroponic tomato |
| Ishii et al. (2022) | Ozone: Sci. & Eng. | Intermittent ozone flushing in NFT hydroponics |
| Khan et al. (2020) | Water Sci. Tech.: Supply | Micro-nanobubble water applications |
| Lei et al. (2023) | Agronomy | Nanobubble irrigation in greenhouse tomatoes |
| Martínez-Sánchez & Aguayo (2019) | Agric. Water Mgmt. | Ozonated water on capsicum seedlings |
| Powell & Scolding (2018) | Reviews in Aquaculture | Direct ozone application in aquaculture |
| Seridou & Kalogerakis (2021) | Env. Sci.: Nano | Ozone micro/nanobubble disinfection |
| Spiliotopoulou et al. (2018) | Water Research | Ozonation control in RAS |
| Tahamolkonan et al. (2022) | Protoplasma | Ozonated water on tomato quality |
| Tamaki et al. (2020) | J. Plant Nutrition | Ozone microbubbles in hydroponic lettuce |
| Zhao et al. (2024) | Frontiers in Plant Science | Ozone nanobubbles in soilless lettuce |
| Zheng et al. (2020) | Ozone: Sci. & Eng. | Ozonated nutrient solution on lettuce roots |
