Ozone micro-bubble aeration using the ceramic ultrafiltration membrane with superior oxidation performance for 2, 4-D
Wei-Ran Han1, Wen-Long Wang1, Tie-Jun Qiao2
1State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), Guangdong Provincial Engineering Research Center for Urban Water Recycling and Environmental Safety, Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
Ceramic membranes enable efficient ozone micro-bubble aeration for enhanced pollutant degradation. This low-energy method improves ozone transfer and hydroxyl radical yield, boosting oxidation performance.
Area of Science:
- Environmental Chemistry
- Water Treatment Technologies
- Advanced Oxidation Processes
Background:
- Ozonation is effective for pollutant degradation but faces challenges with energy costs.
- Micro-bubble aeration enhances ozonation performance but requires significant energy input.
- Developing energy-efficient micro-bubble generation is crucial for advanced oxidation processes.
Purpose of the Study:
- To investigate a low-energy method for generating ozone micro-bubbles using a ceramic ultrafiltration membrane.
- To compare the efficiency of ozone micro-bubble aeration with milli-bubble aeration in terms of ozone transfer and pollutant degradation.
- To elucidate the mechanisms behind the enhanced oxidation performance promoted by ozone micro-bubble aeration.
Main Methods:
- Utilized a ceramic ultrafiltration membrane for ozone micro-bubble (0-80 µm) aeration at specific gaseous pressures.
- Quantified equilibrium aquatic ozone concentrations and apparent ozone transfer rates at varying pH levels.
- Assessed hydroxyl radical (•OH) yield and degradation kinetics of 2,4-D to evaluate oxidation efficiency.
Main Results:
- Micro-bubble aeration significantly increased aquatic ozone concentrations (1.53-3.25 times) and transfer rates (3.12-3.35 times) compared to milli-bubble aeration.
- Hydroxyl radical yield increased by 2.67-3.54 times, indicating enhanced radical-based oxidation.
- Degradation kinetics for 2,4-D were 3.08-4.36 times higher with micro-bubble aeration, with contributions from both O3 and •OH oxidation.
Conclusions:
- Ceramic membrane-based micro-bubble aeration offers a low-energy and efficient approach for pollutant degradation.
- The enhanced performance is attributed to improved ozone transfer and subsequent decomposition, leading to increased •OH generation.
- This study demonstrates a novel mechanism for synchronously enhancing ozone and •OH exposure for superior oxidation outcomes.
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