NICO Articles
ChemicalNanobubbles in Advanced Disinfection and Biofilm Removal: Utilizing Ozone-Based Nanobubbles for Chemical-Free Water Treatment
Nanobubbles, gas bubbles smaller than 200 nanometers, possess exceptional properties such as long stability in water, high surface area-to-volume ratio, and strong negative surface charge. These features allow nanobubbles, especially those containing ozone (ozone nanobubbles or OMNBs), to be highly effective for advanced disinfection, biofilm removal, and contaminant breakdown without relying heavily on chemicals.
Ozone Nanobubbles in Disinfection
Ozone is a highly potent oxidizing agent, recognized for its capability to destroy bacteria, viruses, and other pathogens through the process of oxidation. Conventional ozone bubbles, however, have limited dissolution and low stability in water, reducing their disinfection efficiency. Ozone nanobubbles overcome these limitations by significantly increasing ozone’s residence time in water-from about 20 minutes to up to 3 days-due to their nanoscale size and neutral buoyancy. This prolonged stability improves ozone mass transfer and extends its antimicrobial effectiveness. Ozone nanobubbles disinfect via two main mechanisms:
- Direct oxidation: Ozone molecules react with microbial cell components and contaminants, disrupting cell walls and oxidizing organic pollutants.
- Indirect oxidation: Upon collapse or shrinkage, nanobubbles generate reactive oxygen species (ROS), especially hydroxyl radicals (- OH), which are even more potent oxidants. These ROS can degrade pollutants and inactivate pathogens more efficiently.
The combination of prolonged ozone presence and ROS generation allows more thorough sterilization with lower ozone dosages, reducing energy and chemical inputs. Ozone nanobubbles have been successfully applied in drinking water purification, wastewater treatment, aquaculture, and agriculture, offering a sustainable and chemical-free alternative to traditional disinfectants.
Nanobubbles for Biofilm Removal
Biofilms are protective microbial communities encased in extracellular polymeric substances (EPS) that make them highly resistant to conventional cleaning and chemical disinfection. Nanobubbles offer an innovative approach to biofilm control by:
- Penetrating deeply into the biofilm matrix due to their tiny size.
- Physically disrupting the EPS scaffolding.
- Producing reactive oxygen species such as hydroxyl radicals and hydrogen peroxide, which oxidize biofilm cells and weaken adhesion.
- Providing mechanical action through the dynamic movement and collapse of bubbles, facilitating detachment.
Research shows nanobubbles can reduce biofilm formation by up to 80% and remove established biofilms more effectively than standard tap water treatments. Nanobubbles also help prevent regrowth, contributing to ongoing biofilm management in systems like water pipelines, HVAC, and food processing equipment without requiring harsh chemicals.
Breaking Down Contaminants Without Extensive Chemicals
The oxidative potential of ozone nanobubbles and mechanical energy released upon their collapse allows them to break down complex organic pollutants, including hydrocarbons, pesticides, and industrial chemical residues. This process involves both chemical oxidation by ROS and physical disruption by high-energy microjets generated during bubble collapse.
Furthermore, nanobubbles provide improved oxygen transfer, which supports aerobic microbial communities that naturally biodegrade contaminants, enhancing pollutant removal biologically as well.
Benefits and Future Perspectives
Utilizing ozone nanobubbles for disinfection and biofilm removal offers multiple benefits:
- Effective pathogen inactivation and biofilm disruption with lower chemical input.
- Extended disinfectant activity times and enhanced contaminant breakdown.
- Reduced environmental impact and improved worker safety by minimizing chemical use.
- Energy and cost-efficient operation due to prolonged ozone stability.
- Versatility in applications including water treatment, aquaculture, agriculture, and industrial cleaning.
Ongoing research aims to optimize nanobubble generation and integrate this technology with other advanced oxidation processes, enhancing its efficiency and expanding its use for various contaminants and pathogens.
Ozone nanobubbles signify a substantial innovation in achieving water disinfection and biofilm management without the use of chemicals. By leveraging their unique physical properties and potent oxidizing ability, these nanobubbles achieve superior pathogen inactivation, biofilm removal, and organic pollutant degradation. This innovative technology paves the way for safer, more sustainable, and cost-effective water treatment solutions across multiple industries and environmental settings.
