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Blagojevič M, Bizjan B, Zupanc M, Gostiša J, Perše LS, Centa UG, Stres B, Novak U, Likozar B, Rak G, Repinc SK. Preliminary analysis: Effect of a rotary generator of hydrodynamic cavitation on rheology and methane yield of wastewater sludge. ULTRASONICS SONOCHEMISTRY 2024; 107:106943. [PMID: 38852537 PMCID: PMC11217745 DOI: 10.1016/j.ultsonch.2024.106943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 05/10/2024] [Accepted: 06/04/2024] [Indexed: 06/11/2024]
Abstract
Slightly acidic (pH 5.1) waste sludge with 4.7 % Total Solids (TS) was treated on a laboratory scale pined disc rotary generator of hydrodynamic cavitation (PD RGHC). Influence of four rotor discs with different number of cavitation generation units (CGUs) was investigated: 8-pins, 12-pins, 16-pins and 8-prism elements. The effect of hydrodynamic cavitation (HC) was investigated by analyzing rheological properties, surface tension, dewaterability, and particle size distribution. After subjecting the sludge to 30 cavitation passes, the dewatering ability of the sludge significantly decreased, resulting in a more than two-fold increase in Capillary Suction Time (CST). All regimes were successful in disintegrating particles to smaller sizes. A slight increase of sludge surface tension was measured post cavitation. Cavitated samples displayed a zero-shear viscosity, in contrast to the untreated sample, where viscosity noticeably increased as shear stress decreased. HC did not improve methane yield. Statistically significant correlations between physio-chemical properties and apparent viscosity at low shear stress were identified. Although there were no discernible statistical differences in sludge characteristics, some trends are visible among investigated CGU designs and warrant further research.
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Affiliation(s)
- Marko Blagojevič
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jamova cesta 2, 1000 Ljubljana, Slovenija
| | - Benjamin Bizjan
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jamova cesta 2, 1000 Ljubljana, Slovenija; Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva cesta 6, 1000 Ljubljana, Slovenija
| | - Mojca Zupanc
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva cesta 6, 1000 Ljubljana, Slovenija
| | - Jurij Gostiša
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva cesta 6, 1000 Ljubljana, Slovenija
| | - Lidija Slemenik Perše
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva cesta 6, 1000 Ljubljana, Slovenija
| | - Urška Gradišar Centa
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva cesta 6, 1000 Ljubljana, Slovenija
| | - Blaž Stres
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jamova cesta 2, 1000 Ljubljana, Slovenija; National Institute of Chemistry, Hajdrihova ulica 19, 1000 Ljubljana, Slovenija; Jozef Stefan Institute, Ljubljana, Slovenia, Jamova cesta 39, 1000 Ljubljana, Slovenija; Biotechnical Faculty, University of Ljubljana, Jamnikarjeva ulica 101, 1000 Ljubljana, Slovenija
| | - Uroš Novak
- National Institute of Chemistry, Hajdrihova ulica 19, 1000 Ljubljana, Slovenija
| | - Blaž Likozar
- National Institute of Chemistry, Hajdrihova ulica 19, 1000 Ljubljana, Slovenija
| | - Gašper Rak
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jamova cesta 2, 1000 Ljubljana, Slovenija
| | - Sabina Kolbl Repinc
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jamova cesta 2, 1000 Ljubljana, Slovenija; National Institute of Chemistry, Hajdrihova ulica 19, 1000 Ljubljana, Slovenija.
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2
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Zupanc M, Humar BB, Dular M, Gostiša J, Hočevar M, Repinc SK, Krzyk M, Novak L, Ortar J, Pandur Ž, Stres B, Petkovšek M. The use of hydrodynamic cavitation for waste-to-energy approach to enhance methane production from waste activated sludge. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 347:119074. [PMID: 37804635 DOI: 10.1016/j.jenvman.2023.119074] [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: 05/16/2023] [Revised: 06/30/2023] [Accepted: 08/30/2023] [Indexed: 10/09/2023]
Abstract
Anaerobic digestion in wastewater treatment plants converts its unwanted end product - waste activated sludge into biogas. Even if the process is well established, pre-treatment of the sludge can further improve its efficiency. In this study, four treatment regimes for increasing methane production through prior sludge disintegration were investigated using lab-scale cavitation generator and real sludge samples. Three different cavitating (attached cavitation regime, developed cloud shedding cavitation regime and cavitation in a wake regime) and one non-cavitating regime at elevated static pressure were studied in detail for their effectiveness on physical and chemical properties of sludge samples. Volume-weighted mean diameter D[4,3] of sludge's particles decreased by up to 92%, specific surface area increased by up to 611%, while viscosity (at a shear rate of 3.0 s-1) increased by up to 39% in the non-cavitating and decreased by up to 24% in all three cavitating regimes. Chemical changes were more pronounced in cavitating regimes, where released soluble chemical oxygen demand (sCOD) and increase of dissolved organic matter (DOM) compounds by up to 175% and 122% were achieved, respectively. Methane production increased in all four cases, with the highest increase of 70% corresponding to 312 mL CH4 g-1 COD. However, this treatment was not particularly efficient in terms of energy consumption. The best energy balance was found for the regime with a biochemical methane potencial increase of 43%.
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Affiliation(s)
- Mojca Zupanc
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | | | - Matevž Dular
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Jurij Gostiša
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Marko Hočevar
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Sabina Kolbl Repinc
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, Ljubljana, Slovenia; National Institute of Chemistry, Hajdrihova Ulica 19, 1000 Ljubljana Slovenia
| | - Mario Krzyk
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Lovrenc Novak
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Jernej Ortar
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Žiga Pandur
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Blaž Stres
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, Ljubljana, Slovenia; National Institute of Chemistry, Hajdrihova Ulica 19, 1000 Ljubljana Slovenia; Jozef Stefan Institute, Department of Automation, Biocybernetics and Robotics, Ljubljana, Slovenia
| | - Martin Petkovšek
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia.
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Islam MS, Ranade VV. Enhancement of biomethane potential of brown sludge by pre-treatment using vortex based hydrodynamic cavitation. Heliyon 2023; 9:e18345. [PMID: 37539188 PMCID: PMC10395541 DOI: 10.1016/j.heliyon.2023.e18345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/05/2023] [Accepted: 07/13/2023] [Indexed: 08/05/2023] Open
Abstract
Novel, non-thermal and economically benign pre-treatment process was developed for enhancing valorisation potential of brown sludge generated by dairy industry wastewater treatment plant (WWTP). Vortex-based hydrodynamic cavitation (HC) device was used to quantify influence of pretreatment by measuring biomethane potential (BMP) of untreated and treated brown sludge. Pre-treatment parameters, primarily, pressure drop and number of passes through the cavitation device were varied to quantify influence on BMP. BMP tests were performed at 39 °C containing 5% of total solids in each reactors using an automatic BMP measurement system containing 15 reactors with each volume of 500 mL fitted with overhead stirrer. HC treatment increased the soluble chemical oxygen demand (sCOD) by more than 25% which increased the BMP. HC treatment was able to push the BMP of treated sludge to more than 80% of the theoretical BMP. Volatile solids (VS) removal was more than 65%. Highest methane yield was 376 mL/g-VS of sludge. The methodology and results presented here show significant potential to valorise brown dairy sludge via vortex based hydrodynamic cavitation.
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A Review on Rotary Generators of Hydrodynamic Cavitation for Wastewater Treatment and Enhancement of Anaerobic Digestion Process. Processes (Basel) 2023. [DOI: 10.3390/pr11020514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Abstract
The issue of ever-increasing amounts of waste activated sludge (WAS) produced from biological wastewater treatment plants (WWTPs) is pointed out. WAS can be effectively reduced in the anaerobic digestion (AD) process, where methanogens break down organic matter and simultaneously produce biogas in the absence of oxygen, mainly methane and CO2. Biomethane can then be effectively used in gas turbines to produce electricity and power a part of WWTPs. Hydrodynamic cavitation (HC) has been identified as a potential technique that can improve the AD process and enhance biogas yield. Rotary generators of hydrodynamic cavitation (RGHCs) that have gained considerable popularity due to their promising results and scalability are presented. Operation, their underlying mechanisms, parameters for performance evaluation, and their division based on geometry of cavitation generation units (CGUs) are presented. Their current use in the field of wastewater treatment is presented, with the focus on WAS pre/treatment. In addition, comparison of achieved results with RGHCs relevant to the enhancement of AD process is presented.
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Moftakhari Anasori Movahed S, Calgaro L, Marcomini A. Trends and characteristics of employing cavitation technology for water and wastewater treatment with a focus on hydrodynamic and ultrasonic cavitation over the past two decades: A Scientometric analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 858:159802. [PMID: 36411670 DOI: 10.1016/j.scitotenv.2022.159802] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 09/15/2022] [Accepted: 10/25/2022] [Indexed: 06/16/2023]
Abstract
Cavitation-based technologies have emerged as a sustainable and effective way to treat natural waters and wastewater, considering their increasing scarcity due to pollution and climate change. For this reason, this work aimed to conduct a scientometric analysis on the topic of cavitation for water and wastewater treatment during the last 20 years, from 2001 to August 2022. We focused on hydrodynamic and ultrasonic cavitation as the prevalent methods of inducing cavitation. Furthermore, an in-depth study on the main trends regarding the number of publications and citations, keywords co-occurrence and evolution, and countries' publication trends was carried out to investigate the future direction of this research topic. The data was gathered from the Web of Science database and analyzed by the Visualization Of Similarities software. This work focused on: i) publication and citation trends, ii) scientific categories, iii) countries' contribution to the topic of cavitation, iv) prominent journals, v) keyword co-occurrence and cluster analysis, and vi) keyword evolution analysis. Results showed a significant increase in publications during the past 5 years. The scientific categories with the highest number of publications were "environmental sciences" and "environmental engineering," with a combined share of 19.4 % of publications. Keywords evolution analysis showed that limited focus was given to topics related to "energy" and "energy efficiency" in the field of cavitation, but with the rising importance of each process's sustainability, the attention given to these concepts will increase in the future. Future directions for the topic of cavitation-related water and wastewater treatments will shift towards more environmentally friendly applications of hydrodynamic and ultrasonic cavitation as well as towards more green and sustainable approaches to address the increasing water pollution problems and shortage. Moreover, it will include other uses besides water treatment such as manufacturing nanomaterials food production and medicine.
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Affiliation(s)
- Saman Moftakhari Anasori Movahed
- Department of Environmental Sciences, Informatics and Statistics, University Ca' Foscari of Venice, Via Torino 155, 30172 Venice, Mestre, Italy
| | - Loris Calgaro
- Department of Environmental Sciences, Informatics and Statistics, University Ca' Foscari of Venice, Via Torino 155, 30172 Venice, Mestre, Italy
| | - Antonio Marcomini
- Department of Environmental Sciences, Informatics and Statistics, University Ca' Foscari of Venice, Via Torino 155, 30172 Venice, Mestre, Italy.
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Hong F, Tian H, Yuan X, Liu S, Peng Q, Shi Y, Jin L, Ye L, Jia J, Ying D, Ramsey TS, Huang Y. CFD-assisted modeling of the hydrodynamic cavitation reactors for wastewater treatment - A review. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 321:115982. [PMID: 36104886 DOI: 10.1016/j.jenvman.2022.115982] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 08/05/2022] [Accepted: 08/06/2022] [Indexed: 06/15/2023]
Abstract
Hydrodynamic cavitation has been a promising method and technology in wastewater treatment, while the principles based on the design of cavitational reactors to optimize cavitation yield and performance remains lacking. Computational fluid dynamics (CFD), a supplementation of experimental optimization, has become an essential tool for this issue, owing to the merits of low investment and operating costs. Nevertheless, researchers with a non-engineering background or few CFD fundamentals used straightforward numerical strategies to treat cavitating flows, and this might result in many misinterpretations and consequently poor computations. This review paper presents the rationale behind hydrodynamic cavitation and application of cavitation modeling specific to the reactors in wastewater treatment. In particular, the mathematical models of multiphase flow simulation, including turbulence closures and cavitation models, are comprehensively described, whilst the advantages and shortcomings of each model are also identified and discussed. Examples and methods of the coupling of CFD technology, with experimental observations to investigate into the hydrodynamic behavior of cavitating devices that feature linear and swirling flows, are also critically summarized. Modeling issues, which remain unaddressed, i.e., the implementation strategies of numerical models, and the definition of cavitation numbers are identified and discussed. Finally, the advantages of CFD modeling are discussed and the future of CFD applications in this research area is also outlined. It is expected that the present paper would provide decision-making support for CFD beginners to efficiently perform CFD modeling and promote the advancement of cavitation simulation of reactors in the field of wastewater treatment.
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Affiliation(s)
- Feng Hong
- College of Mechanical and Power Engineering, China Three Gorges University, Yichang, 443002, China; Engineering Research Center of Eco-environmental in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang, 443002, China
| | - Hailin Tian
- Engineering Research Center of Eco-environmental in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang, 443002, China
| | - Xi Yuan
- College of Hydraulic &Environmental Engineering, China Three Gorges University, Yichang, 443002, China; Engineering Research Center of Eco-environmental in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang, 443002, China
| | - Shuchang Liu
- College of Hydraulic &Environmental Engineering, China Three Gorges University, Yichang, 443002, China; Engineering Research Center of Eco-environmental in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang, 443002, China
| | - Qintian Peng
- College of Hydraulic &Environmental Engineering, China Three Gorges University, Yichang, 443002, China; Engineering Research Center of Eco-environmental in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang, 443002, China
| | - Yan Shi
- College of Hydraulic &Environmental Engineering, China Three Gorges University, Yichang, 443002, China; Engineering Research Center of Eco-environmental in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang, 443002, China
| | - Lei Jin
- College of Hydraulic &Environmental Engineering, China Three Gorges University, Yichang, 443002, China; Engineering Research Center of Eco-environmental in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang, 443002, China
| | - Liqun Ye
- Engineering Research Center of Eco-environmental in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang, 443002, China
| | - Jinping Jia
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Diwen Ying
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Thomas Stephen Ramsey
- Engineering Research Center of Eco-environmental in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang, 443002, China; College of Economics & Management, China Three Gorges University, Yichang, 443002, China
| | - Yingping Huang
- College of Hydraulic &Environmental Engineering, China Three Gorges University, Yichang, 443002, China; Engineering Research Center of Eco-environmental in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang, 443002, China.
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7
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Repinc SK, Bizjan B, Budhiraja V, Dular M, Gostiša J, Brajer Humar B, Kaurin A, Kržan A, Levstek M, Arteaga JFM, Petkovšek M, Rak G, Stres B, Širok B, Žagar E, Zupanc M. Integral analysis of hydrodynamic cavitation effects on waste activated sludge characteristics, potentially toxic metals, microorganisms and identification of microplastics. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:151414. [PMID: 34742970 DOI: 10.1016/j.scitotenv.2021.151414] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/26/2021] [Accepted: 10/30/2021] [Indexed: 05/09/2023]
Abstract
Wastewater treatment plants, the last barrier between ever-increasing human activities and the environment, produce huge amounts, of unwanted semi-solid by-product - waste activated sludge. Anaerobic digestion can be used to reduce the amount of sludge. However, the process needs extensive modernisation and refinement to realize its full potential. This can be achieved by using efficient pre-treatment processes that result in high sludge disintegration and solubilization. To this end, we investigated the efficiency of a novel pinned disc rotational generator of hydrodynamic cavitation. The results of physical and chemical evaluation showed a reduction in mean particle size up to 88%, an increase in specific surface area up to 300% and an increase in soluble COD, NH4-N, NO3-N, PO4-P up to 155.8, 126.3, 250 and 29.7%, respectively. Microscopic images confirmed flocs disruption and damage to yeast cells and Epistilys species due to mechanical effects of cavitation such as microjets and shear forces. The observed cell ruptures and cracks were sufficient for the release of small soluble biologically relevant dissolved organic molecules into the bulk liquid, but not for the release of microbial DNA. Cavitation treatment also decreased total Pb concentrations by 70%, which was attributed to the reactions triggered by the chemical effects of cavitation. Additionally, the study confirmed the presence of microplastic particles and fibers of polyethylene, polyethylene terephthalate, polypropylene, and nylon 6 in the waste activated sludge.
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Affiliation(s)
- Sabina Kolbl Repinc
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Benjamin Bizjan
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Vaibhav Budhiraja
- Department of Polymer Chemistry and Technology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Matevž Dular
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Jurij Gostiša
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | | | - Anela Kaurin
- Biotechnical Faculty, Agronomy Department, University of Ljubljana, Ljubljana, Slovenia
| | - Andrej Kržan
- Department of Polymer Chemistry and Technology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Marjetka Levstek
- JP CCN Domzale-Kamnik d.o.o., Domzale-Kamnik WWTP, Domzale, Slovenia
| | | | - Martin Petkovšek
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Gašper Rak
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Blaž Stres
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, Ljubljana, Slovenia; Biotechnical Faculty, Department of Animal Science, University of Ljubljana, Ljubljana, Slovenia; Jozef Stefan Institute, Department of Automation, Biocybernetics and Robotics, Ljubljana, Slovenia
| | - Brane Širok
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Ema Žagar
- Department of Polymer Chemistry and Technology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Mojca Zupanc
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia.
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Sun X, Yang Z, Wei X, Tao Y, Boczkaj G, Yoon JY, Xuan X, Chen S. Multi-objective optimization of the cavitation generation unit structure of an advanced rotational hydrodynamic cavitation reactor. ULTRASONICS SONOCHEMISTRY 2021; 80:105771. [PMID: 34689065 PMCID: PMC8551246 DOI: 10.1016/j.ultsonch.2021.105771] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 09/10/2021] [Accepted: 09/24/2021] [Indexed: 05/12/2023]
Abstract
Hydrodynamic cavitation (HC) has been widely considered a promising technique for industrial-scale process intensifications. The effectiveness of HC is determined by the performance of hydrodynamic cavitation reactors (HCRs). The advanced rotational HCRs (ARHCRs) proposed recently have shown superior performance in various applications, while the research on the structural optimization is still absent. The present study, for the first time, identifies optimal structures of the cavitation generation units of a representative ARHCR by combining genetic algorithm (GA) and computational fluid dynamics, with the objectives of maximizing the total vapor volume, Vvapor , and minimizing the total torque of the rotor wall, M→z . Four important geometrical factors, namely, diameter (D), interaction distance (s), height (h), and inclination angle (θ), were specified as the design variables. Two high-performance fitness functions for Vvapor and M→z were established from a central composite design with 25 cases. After performing 10,001 simulations of GA, a Pareto front with 1630 non-dominated points was obtained. The results reveal that the values of s and θ of the Pareto front concentrated on their lower (i.e., 1.5 mm) and upper limits (i.e., 18.75°), respectively, while the values of D and h were scattered in their variation regions. In comparison to the original model, a representative global optimal point increased the Vvapor by 156% and decreased the M→z by 14%. The corresponding improved mechanism was revealed by analyzing the flow field. The findings of this work can strongly support the fundamental understanding, design, and application of ARHCRs for process intensifications.
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Affiliation(s)
- Xun Sun
- Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education, School of Mechanical Engineering, Shandong University, Jinan 250061, China; National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan 250061, China.
| | - Ze Yang
- Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education, School of Mechanical Engineering, Shandong University, Jinan 250061, China; National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan 250061, China.
| | - Xuesong Wei
- Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education, School of Mechanical Engineering, Shandong University, Jinan 250061, China; National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan 250061, China.
| | - Yang Tao
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
| | - Grzegorz Boczkaj
- Department of Process Engineering and Chemical Technology, Faculty of Chemistry, Gdańsk University of Technology, Gdańsk 80-233, Poland.
| | - Joon Yong Yoon
- Department of Mechanical Engineering, Hanyang University, Ansan 15588, Republic of Korea.
| | - Xiaoxu Xuan
- Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education, School of Mechanical Engineering, Shandong University, Jinan 250061, China; National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan 250061, China.
| | - Songying Chen
- Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education, School of Mechanical Engineering, Shandong University, Jinan 250061, China; National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan 250061, China.
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Gostiša J, Zupanc M, Dular M, Širok B, Levstek M, Bizjan B. Investigation into cavitational intensity and COD reduction performance of the pinned disc reactor with various rotor-stator arrangements. ULTRASONICS SONOCHEMISTRY 2021; 77:105669. [PMID: 34303127 PMCID: PMC8327660 DOI: 10.1016/j.ultsonch.2021.105669] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/09/2021] [Accepted: 07/11/2021] [Indexed: 06/13/2023]
Abstract
In this study, the hydrodynamic cavitation and wastewater treatment performance of a rotary generator with pin disk for hydrodynamic cavitation are investigated. Various geometrical features and arrangements of rotor and stator pins were evaluated to improve the configuration of the cavitation device. The pilot device used to perform the experiments was upgraded with a transparent cover that allows visualization of the hydrodynamic cavitation in the rotor-stator region with high-speed camera and simultaneous measurement of pressure fluctuations. Based on the hydrodynamic characteristics, three arrangements were selected and evaluated with respect to the chemical effects of cavitation on a 200-liter wastewater influent sample. The experimental results show that the rotational speed and the spacing of the rotor pins have the most significant effect on the cavitation intensity and effectiveness, while the pin diameter and the surface roughness are less significant design parameters. Cavitation intensity increases with pin velocity, but can be inhibited if the pins are arranged too close together. At best configuration, COD was reduced by 31% in 15 liquid passes, consuming 8.2 kWh/kg COD. The number of liquid passes also proved to be an important process parameter for improving the energy efficiency.
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Affiliation(s)
- Jurij Gostiša
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Mojca Zupanc
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Matevž Dular
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Brane Širok
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Marjetka Levstek
- JP CCN Domzale-Kamnik d.o.o., Domzale-Kamnik WWTP, Domzale, Slovenia
| | - Benjamin Bizjan
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia.
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Gostiša J, Širok B, Repinc SK, Levstek M, Stražar M, Bizjan B, Zupanc M. Performance evaluation of a novel pilot-scale pinned disc rotating generator of hydrodynamic cavitation. ULTRASONICS SONOCHEMISTRY 2021; 72:105431. [PMID: 33383544 PMCID: PMC7803817 DOI: 10.1016/j.ultsonch.2020.105431] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 12/03/2020] [Accepted: 12/12/2020] [Indexed: 05/14/2023]
Abstract
This study investigates hydrodynamic performance of a novel pinned disc rotating generator of hydrodynamic cavitation in comparison with a serrated disc variant on a pilot-scale. Experimental results show that at a given rotational speed and liquid flow rate, the pinned disc generates more intense cavitation (i.e. lower cavitation number, higher volume fraction of vapor and higher amplitude of pressure fluctuations) than the serrated disc, while also consuming less energy per liquid pass (i.e., higher flow rate and pumping pressure difference of water at similar power consumption). Additionally, mechanical and chemical wastewater treatment performance of the novel cavitator was evaluated on an 800 L influent sample from a wastewater treatment plant. Mechanical effects resulted in a reduction of average particle size from 148 to 38 µm and increase of specific surface area, while the oxidation potential was confirmed by reduction of COD, TOC, and BOD up to 27, 23 and 30% in 60 cavitation passes, respectively. At optimal operating conditions and 30 cavitation passes, pinned disc cavitator had a 310% higher COD removal capacity while consuming 65% less energy per kg of COD removed than the serrated disc cavitator. Furthermore, the specific COD-reduction energy consumption of the pinned disc cavitator on the pilot scale is comparable to the best cases of lab-scale orifice and venturi devices operating at much lower wastewater processing capacity.
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Affiliation(s)
- Jurij Gostiša
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Brane Širok
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Sabina Kolbl Repinc
- Faculty of Civil and Geodetic Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Marjetka Levstek
- JP CCN Domzale-Kamnik d.o.o., Domzale-Kamnik WWTP, Domzale, Slovenia
| | - Marjetka Stražar
- JP CCN Domzale-Kamnik d.o.o., Domzale-Kamnik WWTP, Domzale, Slovenia
| | - Benjamin Bizjan
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Mojca Zupanc
- Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia.
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