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Zhao M, Yang L, Chen F, Zhuang J. Bacterial transport mediated by micro-nanobubbles in porous media. WATER RESEARCH 2024; 258:121771. [PMID: 38768521 DOI: 10.1016/j.watres.2024.121771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 05/08/2024] [Accepted: 05/11/2024] [Indexed: 05/22/2024]
Abstract
Determining the role of micro-nanobubbles (MNBs) in controlling the risk posed by pathogens to soil and groundwater during reclaimed water irrigation requires clarification of the mechanism of how MNBs block pathogenic bacteria. In this study, real-time bioluminescence imaging was used to investigate the effects of MNBs on the transport and spatiotemporal distribution of bioluminescent Escherichia coli 652T7 strain in porous media. The presence of MNBs significantly increased the retention of bacteria in the porous media, decreasing the maximum relative effluent concentration (C/C0) by 78 % from 0.97 (without MNBs) to 0.21 (with MNBs). The results suggested that MNBs provided additional sites at the air-water interface (AWI) for bacterial attachment and acted as physical obstacles to reduce bacterial passage. These effects varied with environmental conditions such as solution ionic strength and pore water velocity. The results indicated that MNBs enhanced electrostatic attachment of bacteria at the AWI and their mechanical straining in pores. This study suggests that adding MNBs in pathogen-containing water is an effective measure for increasing filtration efficiency and reducing the risk of pathogenic contamination during agricultural irrigation.
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Affiliation(s)
- Mingyang Zhao
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenhe District, Shenyang, Liaoning 110016, China; University of Chinese Academy of Sciences, Beijing 100039, China
| | - Liqiong Yang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenhe District, Shenyang, Liaoning 110016, China.
| | - Fengxian Chen
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenhe District, Shenyang, Liaoning 110016, China
| | - Jie Zhuang
- Department of Biosystems Engineering and Soil Science, Institute for a Secure and Sustainable Environment, The University of Tennessee, Knoxville, TN 37996, United States
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Zhao M, Cui H, Wang C, Song Q. Development of a 10-litre pilot scale micro-nano bubble (MNB)-enhanced photocatalytic system for wastewater treatment. ENVIRONMENTAL TECHNOLOGY 2024:1-10. [PMID: 38471071 DOI: 10.1080/09593330.2024.2328660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 03/04/2024] [Indexed: 03/14/2024]
Abstract
A 10-litre pilot scale micro-nano bubble (MNB)-enhanced photocatalytic degradation system was developed using ZnO as the photocatalyst and salicylic acid (SA) as the model pollutant. The effectiveness of the MNB/ZnO/UV system was systematically compared with those of MNB, UV, MNB/UV, MNB/ZnO and ZnO/UV degradation systems. The effects of process parameters, including catalyst dosage, pollutant concentration, air-intake rate, pH and salt content on the degradation of SA, were comprehensively investigated. Optimum performance was obtained at neutral conditions with a catalyst dosage of 0.3 g/L and an air-intake rate of 0.1 L/min. For the degradation of SA, a kinetic constant of 0.04126/min was achieved in the MNB/ZnO/UV system, which is 4.5 times greater than that obtained in the conventional ZnO/UV system. The substantial increase in the degradation rate can be attributed to that the air MNB not only enhanced the gas-liquid mass transfer efficiency but also elevated the concentration of dissolved oxygen. A 10-litre pilot scale MNB/ZnO/UV system was successfully applied to the purification of lake water and river water, demonstrating great application potential for wastewater treatment.
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Affiliation(s)
- Mengyu Zhao
- International Research Center for Photoresponsive Molecules and Materials, School of Chemical and Material Engineering, Jiangnan University, Wuxi, People's Republic of China
| | - Haining Cui
- International Research Center for Photoresponsive Molecules and Materials, School of Chemical and Material Engineering, Jiangnan University, Wuxi, People's Republic of China
| | - Chan Wang
- International Research Center for Photoresponsive Molecules and Materials, School of Chemical and Material Engineering, Jiangnan University, Wuxi, People's Republic of China
| | - Qijun Song
- International Research Center for Photoresponsive Molecules and Materials, School of Chemical and Material Engineering, Jiangnan University, Wuxi, People's Republic of China
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Su H, Sun J, Wang C, Wang H. Temperature impacts on the growth of hydrogen bubbles during ultrasonic vibration-enhanced hydrogen generation. ULTRASONICS SONOCHEMISTRY 2024; 102:106734. [PMID: 38128391 PMCID: PMC10772823 DOI: 10.1016/j.ultsonch.2023.106734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Revised: 12/08/2023] [Accepted: 12/15/2023] [Indexed: 12/23/2023]
Abstract
To improve the hydrogen precipitation performance on the surface of the catalytic layer of the proton exchange membrane (PEM) hydrogen cathode, ultrasonic vibration was employed to accelerate the detachment of hydrogen bubbles on the surface of the catalytic layer. Based on the energy and mechanical analyses of nano and microbubbles, the hydrogen bubble generation mechanism and the effect of temperature on bubble parameters during the evolution process when the ultrasonic field is coupled with the electric field are investigated. The nucleation frequency of the hydrogen bubbles, the relationship between the pressure and temperature and the operating temperature during the generation and detachment of bubbles as well as the detachment radius of bubbles under the action of the ultrasonic field are obtained. The effects of ultrasound and temperature on hydrogen production were verified by visual experiments. The results show that the operating temperature affects the nucleation, growth, and detachment processes of hydrogen bubbles. The effect of temperature on the nucleation frequency of bubbles mainly comes from the Gibbs free energy required for the electrolysis reaction. The bubble radius and growth rate are both related to the temperature to the power of one-third. Ultrasonic waves enhance the separation of hydrogen bubbles from the catalyst surface by acoustic cavitation and impact effects. An increase in the working temperature reduces the activation energy barriers to be overcome for the electrolysis reaction of water, which together with a decrease in the Gibbs free energy and the surface tension coefficient, leads to an increase in the nucleation frequency of the catalytic layer and a decrease in the radius of bubble detachment, and thus improves the hydrogen precipitation performance. Visualization experiments show that in actual PEM hydrogen production, ultrasonic intensification can promote the formation of nucleation sites. The ultrasonic induced fine bubble flow not only has a drag effect on the bubble, but also intensifies the polymerization growth of the bubble due to the impact of the fine bubble flow, thus speeding up the detachment of the bubble, shortening the covering time of the hydrogen bubble on the surface of the catalytic electrode, reducing the activation voltage loss and improve the hydrogen production efficiency of PEM. The experimental results show that when the electrolyte is 60°C, the maximum hydrogen production efficiency of ultrasound is increased by 7.34%, and the average hydrogen production efficiency is increased by 5.83%.
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Affiliation(s)
- Hongqian Su
- School of Environment and Energy Engineering, Beijing University of Civil Engineering and Architecture, Beijing 100044, China; Building Environment and Energy Power Engineering Experimental Center, Beijing University of Civil Engineering and Architecture, Beijing 100044, China
| | - Jindong Sun
- School of Environment and Energy Engineering, Beijing University of Civil Engineering and Architecture, Beijing 100044, China; Building Environment and Energy Power Engineering Experimental Center, Beijing University of Civil Engineering and Architecture, Beijing 100044, China.
| | - Caizhu Wang
- School of Environment and Energy Engineering, Beijing University of Civil Engineering and Architecture, Beijing 100044, China; Building Environment and Energy Power Engineering Experimental Center, Beijing University of Civil Engineering and Architecture, Beijing 100044, China
| | - Haofeng Wang
- School of Environment and Energy Engineering, Beijing University of Civil Engineering and Architecture, Beijing 100044, China; Building Environment and Energy Power Engineering Experimental Center, Beijing University of Civil Engineering and Architecture, Beijing 100044, China
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Lyu T, Wu Y, Zhang Y, Fan W, Wu S, Mortimer RJG, Pan G. Nanobubble aeration enhanced wastewater treatment and bioenergy generation in constructed wetlands coupled with microbial fuel cells. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 895:165131. [PMID: 37364834 DOI: 10.1016/j.scitotenv.2023.165131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 06/09/2023] [Accepted: 06/23/2023] [Indexed: 06/28/2023]
Abstract
Artificial aeration is a widely used approach in wastewater treatment to enhance the removal of pollutants, however, traditional aeration techniques have been challenging due to the low oxygen transfer rate (OTR). Nanobubble aeration has emerged as a promising technology that utilise nano-scale bubbles to achieve higher OTRs owing to their large surface area and unique properties such as longevity and reactive oxygen species generation. This study, for the first time, investigated the feasibility of coupling nanobubble technology with constructed wetlands (CWs) for treating livestock wastewater. The results demonstrated that nanobubble-aerated CWs achieved significantly higher removal efficiencies of total organic carbon (TOC) and ammonia (NH4+-N), at 49 % and 65 %, respectively, compared to traditional aeration treatment (36 % and 48 %) and the control group (27 % and 22 %). The enhanced performance of the nanobubble-aerated CWs can be attributed to the nearly three times higher amount of nanobubbles (Ø < 1 μm) generated from the nanobubble pump (3.68 × 108 particles/mL) compared to the normal aeration pump. Moreover, the microbial fuel cells (MFCs) embedded in the nanobubble-aerated CWs harvested 5.5 times higher electricity energy (29 mW/m2) compared to the other groups. The results suggested that nanobubble technology has the potential to trigger the innovation of CWs by enhancing their capacity for water treatment and energy recovery. Further research needs are proposed to optimise the generation of nanobubbles, allowing them to be effectively coupled with different technologies for engineering implementation.
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Affiliation(s)
- Tao Lyu
- School of Water, Energy and Environment, Cranfield University, College Road, Bedfordshire MK43 0AL, UK
| | - Yuncheng Wu
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210000, China
| | - Yang Zhang
- Shenzhen Guanghuiyuan Environment Water Co., Ltd., Shenzhen 518038, China
| | - Wei Fan
- School of Environment, Northeast Normal University, 2555 Jingyue Street, Changchun 130117, China
| | - Shubiao Wu
- Department of Agroecology, Aarhus University, Blichers Allé 20, 8830 Tjele, Denmark
| | - Robert J G Mortimer
- School of Humanities, York St John University, Lord Mayor's Walk, York YO31 7EX, UK
| | - Gang Pan
- School of Humanities, York St John University, Lord Mayor's Walk, York YO31 7EX, UK.
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Kakiuchi K, Kozuka T, Mase N, Miyasaka T, Harii N, Takeoka S. Do Ultrafine Bubbles Work as Oxygen Carriers? LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:1354-1363. [PMID: 36649623 DOI: 10.1021/acs.langmuir.2c01209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Fine bubbles (FBs) are bubbles with sizes less than 100 μm and are divided into ultrafine bubbles (UFBs, < 1 μm) and microbubbles (MBs, 1-100 μm) depending on their size. Although FB aeration is known as a more efficient way than macrobubble aeration to increase the oxygen level in unoxygenated water, few reports have demonstrated whether dispersed UFBs work as oxygen carriers or not. Furthermore, oxygen supersaturation is one of the attractive characteristics of FB dispersion, but the reason is yet to be revealed. In this study, we evaluated the relationship between the FBs, especially UFB concentration, and oxygen content in several situations to reveal the two questions. The FB concentration and oxygen content were examined using particle analyzers and our developed oxygen measurement method, which can measure the oxygen content in FB dispersion, respectively. First, in the evaluations of the oxygen dispersion from UFBs with respect to the surrounding oxygen level, UFBs did become neither small nor diminish even in degassed water. Second, the changes in UFBs and oxygen content upon storage temperature and the existence of a lid during storage were evaluated, and there was no correlation between them. It means UFBs contribute little to the oxygen content in UFB dispersion. Furthermore, the oxygen content in the UFB dispersion decreased over time identically as that of the oxygen-supersaturated water with little UFBs. Third, we evaluated the relationship between FB concentration and oxygen content during FB generation by measuring them simultaneously. The results showed that dispersed MB and UFB concentrations did not account for the supersaturation of the FB dispersion. From the result, it was revealed that 100-200 nm of UFBs themselves did not work as oxygen carriers, and the oxygen supersaturation in FB dispersions was due to the supersaturated state of dissolved oxygen that was prepared during the FB generation process.
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Affiliation(s)
- Kenta Kakiuchi
- Faculty of Science and Engineering, Waseda University (TWIns), 162-8480Tokyo, Japan
| | - Tomoki Kozuka
- Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, 432-8561Shizuoka, Japan
| | - Nobuyuki Mase
- Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, 432-8561Shizuoka, Japan
- Research Institute of Green Science and Technology, Shizuoka University, 432-8561Shizuoka, Japan
| | - Takehiro Miyasaka
- Department of Human Environmental Science, Shonan Institute of Technology, 251-8511Fujisawa, Kanagawa, Japan
| | - Norikazu Harii
- Department of Community and Family Medicine, Faculty of Medicine, University of Yamanashi, 409-3898Yamanashi, Japan
| | - Shinji Takeoka
- Faculty of Science and Engineering, Waseda University (TWIns), 162-8480Tokyo, Japan
- Research Institute for Science and Engineering, Waseda University, 169-8555Tokyo, Japan
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