R. Govind
University of Cincinnati,
United States
Keywords: water, wastewater, treatment, nanobubbles, ultrafine bubbles, sustainability, energy
Summary:
Nanobubbles, known as ultrafine bubbles, revolutionize wastewater treatment and water disinfection. These smaller than 200 nanometers in diameter gas-filled cavities boast unique properties that enhance their effectiveness across various applications. Unlike microbubbles, nanobubbles exhibit remarkable stability in liquids due to their diminutive size, high internal pressure, and negative surface charge. Their impressive surface area-to-volume ratio boosts reactivity and interaction with contaminants. Why Nanobubbles? Nanobubbles can be created through electrolysis, cavitation, and gas injection. Their stability, owing to zeta potential, ensures they remain intact rather than quickly merging and rising to the surface—this makes them an intriguing and promising tool in water treatment. Applications in Wastewater Treatment: Air nanobubbles enhance oxygen transfer efficiency, significantly promoting aerobic biological processes crucial for breaking down organic matter. This provides a reliable and efficient wastewater treatment solution, showcasing this technology's immense potential. The Power of Oxygen and Ozone Nanobubbles: Oxygen nanobubbles concentrate oxygen sources, improving the efficiency of aerobic microbial degradation of organic pollutants—crucial in aquaculture for maintaining high dissolved oxygen levels. With their potent oxidizing properties, ozone nanobubbles are highly effective in disinfection and degradation of organic pollutants, thanks to their extended half-life in water. Boosting Efficiency and Environmental Benefits: Nanobubbles support the growth of aerobic bacteria, aiding in the effective breakdown of organic matter and instilling confidence in wastewater treatment technology. They also play a pivotal role in flotation separation processes by attaching to suspended particles and facilitating the removal of oils, greases, and hydrophobic contaminants. In this paper a novel method of generating nanobubbles, less than 1 micron in diameter, at a high gas-liquid ratio will be presented. Field data on the performance of this technology in treating wastewater with substantially low energy consumption than conventional aeration, will also be discussed. A novel mechanism for the stability and generation of hydroxyl radicals in treating wastewater contaminants will be discussed with its application to data presented by other researchers.