The Strengthening Effect of Micro-nano Bubbles on The Ozone Oxidation And Disinfection Process

Research Progress on the Enhancement Effects of Micro- and Nano-Bubbles on Ozone Oxidation and Disinfection Processes

With the increasing demand for water pollution control, ozone micro-nano bubble technology, due to its unique physical and chemical properties, has demonstrated significant advantages in the degradation of pollutants and disinfection. This article will systematically analyze the dual mechanisms by which this technology enhances the efficiency of ozone oxidation and explore its application value in scenarios such as industrial wastewater and drinking water safety.

PART 01

A breakthrough improvement in mass transfer efficiency

Micro-nano bubbles (with particle sizes ranging from 0.1 to 100 μm) revolutionize the mass transfer bottleneck of traditional ozone processes through their ultra-high specific surface area and prolonged retention in water. Experimental data shows that their volumetric mass transfer coefficient can reach 4.7 times that of conventional aeration, and the equilibrium concentration of ozone in the liquid phase can increase by 3.25 times. This characteristic stems from the fact that the bubbles can hover in water for several minutes to several weeks, exponentially increasing the gas-liquid contact time.

The breakthrough in ceramic membrane aeration technology further optimizes the bubble distribution characteristics. Under a pressure of 0.14 to 0.19 MPa, 40-80 μm microbubbles are generated and their sizes are precisely controlled by a fine cutting net, effectively preventing premature coalescence of the bubbles. This design ensures a stable ozone dissolution concentration of 13.4 mg/L, a 70% increase over traditional methods, laying a material foundation for subsequent oxidation reactions.

PART 02

Innovations in the mechanism of free radical generation

The "hot spot effect" at the bubble interface is the key to the generation of hydroxyl radicals (·OH). At the moment of micro-nano bubble rupture, the local temperature at the gas-liquid interface can reach 3000K. The high-pressure environment causes water molecules to dissociate and produce highly oxidative ·OH. Its redox potential (2.8V) far exceeds that of ozone molecules (2.07V), and it can indiscriminately attack the molecular structure of organic pollutants. Kinetic studies reveal the quantitative law of increased radical yield: the hydroxyl radical yield in the microbubble system is 3.54 times higher than that in the millimeter bubble system. In the degradation experiments of refractory pollutants such as 2,4-D, the contribution rate of radicals reaches 54.1% - 64.2%. This non-selective oxidation characteristic makes this technology particularly suitable for industrial wastewater containing stubborn pollutants such as benzene series and chlorinated hydrocarbons.

PART 03

Validation of pollutant degradation efficiency

In the context of dyeing and printing wastewater treatment, the micro-nano bubble ozone technology has achieved a qualitative leap in pollutant removal rates. Actual operation data shows that the decolorization rate of azo dyes in textile wastewater exceeds 95%, and the COD removal rate is over 85%, with the effluent quality stably meeting the GB 4287-2012 discharge standard. This is mainly attributed to the synergistic effect mechanism of ozone and free radicals.

For groundwater pollution remediation, this technology has increased the degradation kinetic constant of benzene series substances by 2.3 times. A pilot test in a chlorobenzene-contaminated site demonstrated that after adopting the micro-nano bubble ozone system, the half-life of pollutants was shortened from 48 hours in traditional processes to 16 hours, and the treatment cost was reduced by 40%. This high efficiency is due to the special affinity effect of microbubbles on hydrophobic organic substances.

PART 04

Pathways for enhancing disinfection performance

The improvement in microbial inactivation efficiency is attributed to a triple action mechanism: hydroxyl radical oxidation, physical shock from bubble collapse, and direct ozone action. Experiments have confirmed that the required CT value (concentration-time product) for achieving a 4-log inactivation of Escherichia coli is only one-third of that of traditional ozone disinfection, and a 99.99% sterilization rate can be achieved at a low dose of 0.5 mg/L.

In the field of food sterilization, this technology demonstrates unique advantages. Micro-nano bubbles extend the half-life of ozone to 23 times that of traditional methods, continuously enhancing the sterilization effect. Experiments on the inactivation of Salmonella have shown that a 7D sterilization effect can be achieved within 5 minutes of contact, and no harmful by-products such as bromate are generated, ensuring the biological safety of drinking water.

PART 05

Progress in engineering applications

The new reactor design optimizes bubble distribution through multi-stage cutting nets. The inner cutting net (with a pore size of 30 μm) and the outer cutting net (with a pore size of 50 μm) are arranged at a 30-degree angle to each other, effectively solving the problem of micron bubble escape due to upward floatation. Engineering data shows that this design has increased the ozone utilization rate from 45% in traditional processes to 82%, and reduced energy consumption by 35%.

The modular device has been successfully applied in the treatment of pharmaceutical wastewater. A ten-thousand-ton-level project case shows that after adopting the micro-nano bubble ozone system, the degradation efficiency of cephalosporin antibiotics has increased by 2.8 times, and the operating cost is 60% lower than that of the Fenton process. The core of the device includes a wastewater chamber, a micro-bubble generation unit, an ozone catalytic tower, and an intelligent control system, achieving fully automated operation throughout the process.