Wastewater Treatment
How are Nanobubbles being used for Wastewater Treatment
Nanobubbles are increasingly being adopted in the wastewater treatment industry due to their unique physical and chemical properties that enhance the efficiency, effectiveness, and sustainability of various treatment processes. Defined as gas-filled cavities smaller than 200-nm in diameter, nanobubbles differ significantly from conventional bubbles in that they remain suspended in liquid for extended periods, exhibit near-neutral buoyancy, and collapse in ways that generate beneficial chemical reactions. These attributes make them particularly valuable in municipal and industrial wastewater treatment systems.
One of the most significant advantages of nanobubbles is their ability to improve oxygen transfer efficiency (OTE). In conventional aeration systems, large bubbles rise rapidly to the surface and release oxygen into the atmosphere before it can be fully absorbed into the liquid. In contrast, nanobubbles remain dispersed within the water column for hours or even days, allowing for continuous and efficient diffusion of oxygen. This enhanced gas transfer supports aerobic microbial activity in biological treatment processes, such as activated sludge systems, sequencing batch reactors (SBRs), and membrane bioreactors (MBRs), where oxygen is essential for breaking down organic contaminants.
Another critical function of nanobubbles in wastewater treatment is their ability to generate reactive oxygen species (ROS) upon collapse. When nanobubbles are destabilized—whether through changes in pressure, temperature, or chemical conditions, they implode, releasing a burst of energy that forms hydroxyl radicals and other ROS. These species are powerful oxidizers capable of degrading complex organic pollutants, inactivating bacteria and viruses, and assisting in advanced oxidation processes (AOPs). This makes nanobubbles highly effective in tertiary treatment stages where further purification and disinfection are required.
In addition to enhancing biological and chemical treatment, nanobubbles also play a role in physical treatment processes. They improve flotation efficiency by increasing the surface area available for particle attachment. In systems such as dissolved air flotation (DAF), the presence of nanobubbles facilitates the agglomeration and removal of suspended solids, oils, and grease. Moreover, nanobubbles can penetrate and disrupt biofilms and sludge flocs, leading to improved sludge digestion and reduced sludge volume. This contributes to more effective dewatering and lower sludge handling costs.
From an operational perspective, nanobubble technology is relatively easy to integrate into existing treatment infrastructure. Nanobubble generators can be installed inline or as side-stream units and typically require minimal modifications to existing piping and tanks. They can be configured to use various gases, such as air, oxygen, or ozone, depending on the treatment objective. Their high efficiency also results in energy savings by reducing the demand on blowers and mixers, which are traditionally among the most energy-intensive components of a treatment plant.
In summary, nanobubbles offer a multifaceted and energy-efficient solution for wastewater treatment. They improve oxygen transfer and microbial activity in biological systems, enhance oxidation and disinfection processes, support the removal of suspended solids, and reduce sludge volume. As water treatment facilities face growing challenges related to energy use, contaminant complexity, and environmental regulations, nanobubble technology represents a promising and adaptable advancement in the field.
Key Features
1. Exceptional Surface Area for Maximum Contact:
- NICO Nanobubbles are incredibly small—resulting in a dramatically higher surface area-to-volume ratio. This maximizes contact with contaminants, driving faster and more efficient interactions at the microscopic level.
2. Suspended for Sustained Impact:
- Unlike conventional bubbles that rise and burst within seconds, NICO Nanobubbles remain suspended in water for extended durations. This stability ensures longer-lasting treatment performance and greater process effectiveness.
3. Superior Gas Delivery Efficiency:
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Engineered for optimal gas transfer, NICO Nanobubbles significantly enhance the delivery of oxygen, ozone, and other treatment gases into water. This boosts their effectiveness in purification and aeration—without the inefficiencies of traditional methods.
How are Nanobubbles being used in the WWT Industry
Nanobubbles are increasingly being used across multiple stages of wastewater treatment because of their unique physicochemical properties , extremely small size (<200 nm), high internal pressure, long stability in water, and ability to generate reactive oxygen species (ROS).
Here’s an overview of their applications in the wastewater treatment industry:
1. Aeration & Oxygen Transfer Enhancement
- Nanobubble oxygenation systems provide much higher oxygen transfer efficiency (OTE) than conventional diffused aeration or coarse-bubble systems.
- Because nanobubbles remain suspended for long periods, they continuously dissolve oxygen, leading to:
- Improved biological oxygen demand (BOD) and chemical oxygen demand (COD) removal rates.
- Reduced energy costs (up to 30–40% lower vs traditional blowers).
- Enhanced microbial activity in aerobic basins and MBBR/MBR systems.
2. Sludge Reduction & Dewatering
- Nanobubbles (especially ozone or air nanobubbles) break down extracellular polymeric substances (EPS) that bind sludge flocs.
- This improves:
- Dewatering efficiency (lower sludge volume and disposal costs).
- Digestibility in anaerobic or aerobic digesters.
- Ozone nanobubbles also oxidize recalcitrant organics, reducing the need for chemical conditioners.
3. Advanced Oxidation Processes (AOP)
- Ozone and hydroxyl radical nanobubbles (•OH) play a key role in degrading persistent organic pollutants (POPs), pharmaceuticals, dyes, and endocrine-disrupting compounds (EDCs).
- Used as a chemical-free disinfection and oxidation method in tertiary treatment.
- Often integrated with UV or hydrogen peroxide for synergistic effects (e.g., O₃–H₂O₂–nanobubble AOP).
4. Disinfection and Pathogen Inactivation
- Nanobubbles generate reactive oxygen species (ROS) upon collapse, including hydroxyl radicals and superoxide ions.
- These radicals destroy bacterial cell walls and viral membranes without leaving harmful residues, providing:
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Sustainable pathogen reduction.
- Replacement or supplementation of chlorine-based disinfection.
5. Odor Control & Hydrogen Sulfide (H₂S) Suppression
- Air or oxygen nanobubbles oxidize reduced sulfur compounds such as H₂S and mercaptans.
- This eliminates odor and prevents corrosion in collection systems and wet wells.
6. Membrane Fouling Reduction
- In MBR and RO systems, nanobubbles help:
- Prevent biofilm formation by oxidizing organic residues.
- Clean membrane pores via microcavitation effects.
- This extends membrane lifespan and lowers chemical cleaning frequency.
7. Anaerobic Digestion & Biogas Enhancement
- Methane (CH₄) and oxygen nanobubbles enhance microbial activity and hydrolysis efficiency in anaerobic digesters.
- Results include:
- Faster digestion rates.
- Increased biogas yield and methane concentration.
- Better solubilization of organic matter.
8. Aquaculture and Reuse Applications
- Treated effluent enriched with oxygen nanobubbles supports fish hatcheries and hydroponics.
- Promotes dissolved oxygen stability, improves water clarity, and reduces algae growth.
Key Characteristics of Nanobubbles
Benefits of Nanobubbles in STP & WWTP
Superior Oxidation and Treatment Performance
- Accelerated Advanced Oxidation Processes (AOPs): Nanobubbles enable the formation of powerful reactive oxygen species (ROS), including hydroxyl radicals (•OH), which are exceptionally effective at breaking down persistent organic pollutants.
- Elevated Contaminant Breakdown: With greater reactivity and expanded contact surface, NICO Nanobubbles significantly enhance the removal of both organic and inorganic contaminants—such as pharmaceutical residues, pesticides, and industrial chemicals—delivering cleaner, safer effluent.
How Do Nanobubbles Work?
Advancing Wastewater Treatment Performance in STPs & WWTPs
- Stronger Oxidation Mechanisms: Nanobubbles play a pivotal role in intensifying oxidation processes by promoting the formation of reactive oxygen species (ROS), including hydroxyl radicals. These radicals are known for their ability to rapidly break down stubborn organic compounds present in wastewater.
- More Effective Pollutant Elimination: Thanks to their ultra-small size and enhanced surface activity, NICO Nanobubbles increase interaction with dissolved contaminants. This leads to faster and more complete removal of a wide range of pollutants—including pharmaceutical residues, agrochemicals, and industrial waste—ensuring cleaner and more compliant discharge.