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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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Liu Y, Li B. Numerical Investigation of the Cavitation Characteristics in Venturi Tubes: The Role of Converging and Diverging Sections. APPLIED SCIENCES 2023; 13:7476. [DOI: 10.3390/app13137476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Cavitation is a typical physical process that has shown to be highly valuable in the wastewater treatment field. This study aims to investigate the effects of the converging and diverging sections of a Venturi tube on the cavitation flow field. Multiphase flows in tubes are presented using the mixture model and the standard k-ε model. And the Schnerr and Sauer cavitation model is employed to simulate the vapor–liquid phase transition process. Both grid independence and the numerical method’s feasibility were validated before the research. The results showed that the influence of the divergence section length on Venturi cavitation characteristics depends on the provided pressure conditions. As the pressure increases, shorter divergence sections result in more significant cavitation effects. The length of the convergence section displays various cavitation behaviors under different pressure situations. A small contraction section length can achieve better cavitation effects in high-pressure applications, whereas the opposite is true in low-pressure cases. Within the scope of this study, it was observed that the Venturi tube with a divergent section of 14 Lt and a convergent one of 2.4 Lt provided enhanced cavitation performance when subjected to inlet pressures ranging from 0.8 to 1.2 MPa. Our findings indicate that the selection of converging and diverging section lengths in Venturi tubes should consider the corresponding operational pressure conditions, which provides valuable guidance and engineering significance in the research and development of Venturi cavitation devices in hydraulic engineering.
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Affiliation(s)
- Yi Liu
- Faculty of Mechanical Engineering & Automation, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Bin Li
- Faculty of Mechanical Engineering & Automation, Zhejiang Sci-Tech University, Hangzhou 310018, China
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Dong L, Zhao T, Cui Y, Li Z, Chen L, Pang C, Wang Y. Investigation of sludge disintegration using vortex cavitation circulating fluidised grinding technology. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 331:117290. [PMID: 36642050 DOI: 10.1016/j.jenvman.2023.117290] [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: 10/21/2022] [Revised: 12/23/2022] [Accepted: 01/10/2023] [Indexed: 06/17/2023]
Abstract
Waste-activated sludge (WAS) is regarded as a source of hazardous waste pollution from sewage treatment plants. To efficiently deal with WAS, vortex cavitation circulating fluidised grinding technology (VCCFGT) was proposed as a novel circulating fluidisation technology (CFT) to disintegrate WAS. To be specific, we investigated the effects of disintegration duration, pressure, and filling ratio of mill balls on sludge disintegration. The results of chemical and physical evaluation showed that the values of soluble chemical oxygen demand (SCOD), disintegration degree (DDSCOD), DNA, protein, carbohydrate, and NH4+-N increased with the increase in the filling ratio of the mill balls. Under a pressure and filling ratio of 0.30 MPa and 1.6%, respectively, the maximum effect was achieved after 60 min of treatment. Compared to those in the treatment without mill balls, the values of SCOD, DDSCOD, DNA, protein, carbohydrate, and NH4+-N in the treatment using mill balls increased by 218, 229, 230, 177, 371, and 190%, respectively. As a result of this technology, the temperature of the sludge dramatically increased, rising approximately 42.9 °C. Compared to that of the raw sludge, the sludge particle size after treatment was reduced by 83.25% at most, and the morphology of the sludge comprised smaller flocs. Compared to that of the ball-milling method, the mill balls filling ratio of VCCFGT reduced by 93.60-98.12%. Compared to that of sludge disintegration by the vortex cavitation method, VCCFGT indicating good disintegration degree (increased by 229%) and economic feasibility. VCCFGT has good application prospects for sludge disintegration. The main mechanisms of sludge disintegration and organic release include centrifugal force, grinding, shear force, cavitation, and cyclic fatigue effects, among which grinding plays a leading role. This study concluded that CFT can effectively disintegrate sludge flocs and disrupt bacterial cell walls.
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Affiliation(s)
- Liang Dong
- Xi'an University of Technology, School of Mechanical and Precision Instrument Engineering, Xi'an, Shanxi, 710000, China
| | - Tong Zhao
- Xi'an University of Technology, School of Mechanical and Precision Instrument Engineering, Xi'an, Shanxi, 710000, China.
| | - Yahui Cui
- Xi'an University of Technology, School of Mechanical and Precision Instrument Engineering, Xi'an, Shanxi, 710000, China
| | - Zhe Li
- Xi'an University of Technology, School of Mechanical and Precision Instrument Engineering, Xi'an, Shanxi, 710000, China
| | - Linping Chen
- Xi'an University of Technology, School of Mechanical and Precision Instrument Engineering, Xi'an, Shanxi, 710000, China
| | - Chaofan Pang
- Xi'an University of Technology, School of Mechanical and Precision Instrument Engineering, Xi'an, Shanxi, 710000, China
| | - Yunqian Wang
- Xi'an University of Technology, School of Mechanical and Precision Instrument Engineering, Xi'an, Shanxi, 710000, China
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Abbasi E, Saadat S, Karimi Jashni A, Shafaei MH. A novel method for optimization of slit Venturi dimensions through CFD simulation and RSM design. ULTRASONICS SONOCHEMISTRY 2020; 67:105088. [PMID: 32279032 DOI: 10.1016/j.ultsonch.2020.105088] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 02/29/2020] [Accepted: 03/22/2020] [Indexed: 05/14/2023]
Abstract
This research presents a novel comprehensive method for optimizing the design of cavitating slit Venturi for a given cavitation intensity. This method is applicable to any cavitation number and can be used to provide the Venturi geometry that is suitable for a specific application. In this paper, cavitating Venturi design process is represented in seven steps. As an example, for the cavitation number of 0.2, geometrical and operational parameters of the Venturi were determined using the proposed seven steps. During the design process, the Venturi discharge coefficient was calculated using computational fluid dynamics (CFD) simulations. Furthermore, Venturi parameters such as inlet pressure, throat area, width, length, height and divergence angle, were optimized by the combination of CFD and Response Surface Methodology (RSM). In addition to calculating the mentioned optimum parameters, other hydraulic parameters of Venturi including discharge coefficient, flowrate, throat velocity, cavitation volume and length were also determined. Finally, the proposed design method in this study was verified by conducting sets of laboratory experiments.
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Affiliation(s)
- Elahe Abbasi
- Department of Civil and Environmental Engineering, School of Engineering, Shiraz University, Shiraz, Fars 7134851156, Iran
| | - Solmaz Saadat
- Department of Civil and Environmental Engineering, School of Engineering, Shiraz University, Shiraz, Fars 7134851156, Iran
| | - Ayoub Karimi Jashni
- Department of Civil and Environmental Engineering, School of Engineering, Shiraz University, Shiraz, Fars 7134851156, Iran
| | - Mohammad Hadi Shafaei
- Department of Aerospace Engineering and Energy, School of Mechanical Engineering, Shiraz University, Fars, Iran
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Mancuso G, Langone M, Andreottola G. A critical review of the current technologies in wastewater treatment plants by using hydrodynamic cavitation process: principles and applications. JOURNAL OF ENVIRONMENTAL HEALTH SCIENCE & ENGINEERING 2020; 18:311-333. [PMID: 32399243 PMCID: PMC7203374 DOI: 10.1007/s40201-020-00444-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 01/14/2020] [Indexed: 05/22/2023]
Abstract
In the last decade, hydrodynamic cavitation (HC) was increasingly used in the field of wastewater treatment. Due to its oxidative capability, HC was applied to treat aqueous effluents polluted by organic, toxic and bio-refractory contaminants, whereas its mechanical and chemical effects have allowed to disintegrate cells of microorganisms in biological applications. Due to their geometries, HC can be detected in some reactors, in which a variation of hydraulic parameters in the fluid such as flow pressure and flow velocity is induced. HC process involves the formation, growth, implosion and subsequent collapse of cavities, occurring in a very short period of time and releasing large magnitudes of power. In this paper, the vast literature on HC is critically reviewed, focusing on the basic principles behind it, in terms of process definition and analysis of governing mechanisms of both HC generation and pollutants degradation. The influence of various parameters on HC effectiveness was assessed, considering fluid properties, construction features of HC devices and technological aspects of processes. The synergetic effect of HC combined with chemicals or other techniques was discussed. An overview of the main devices used for HC generation and different existing methods to evaluate the cavitation effectiveness was provided. Knowledge buildup and optimization for such complex systems from mathematical modeling was highlighted.
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Affiliation(s)
- Giuseppe Mancuso
- Department of Agricultural and Food Sciences, Alma Mater Studiorum, University of Bologna, viale Giuseppe Fanin 50, 40127 Bologna, Italy
| | - Michela Langone
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123 Trento, Italy
| | - Gianni Andreottola
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123 Trento, Italy
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Mancuso G, Langone M, Andreottola G, Bruni L. Effects of hydrodynamic cavitation, low-level thermal and low-level alkaline pre-treatments on sludge solubilisation. ULTRASONICS SONOCHEMISTRY 2019; 59:104750. [PMID: 31473425 DOI: 10.1016/j.ultsonch.2019.104750] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 08/21/2019] [Accepted: 08/22/2019] [Indexed: 05/07/2023]
Abstract
WAS is a polluting and hazardous waste generated in WWTPs that must be treated to prevent pollution and human health risks. Anaerobic digestion is the most used process for sludge stabilization. However, it must be improved in terms of both speed and extend of degradation. With the purpose of reducing the energy and chemical consumption linked to sludge treatment, in this study, different anaerobic digestion pre-treatments such as low-level mechanical (hydrodynamic cavitation, 2 bar), low-level thermal (50 °C) and low-level alkaline (NaOH, KOH and Ca(OH)2, pH 10) methods, and a combination thereof, were tested as strategies to improve sludge solubilisation. When the pre-treatments were used alone, the alkaline pre-treatment showed the highest sludge solubilisation. Among the alkaline reagents tested, NaOH and KOH led to higher DDPCOD (41.6 and 39.4%), while only 8.4% was achieved by using Ca(OH)2. However, the low-level hydrodynamic cavitation assisted thermo-alkaline pre-treatment was the most efficient in terms of both sludge solubilisation (DDPCOD = 53.0%) and energy efficiency (EE = 64.5 mgΔSCOD kJ-1). The synergetic effects of the combined pre-treatment were also confirmed by the highest release of EPS. Furthermore, cytometric analyses showed that the main mechanism involved in sludge solubilisation for the investigated pre-treatments was flocs disintegration rather than cell lysis.
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Affiliation(s)
- Giuseppe Mancuso
- Centre for Water Resources Research, School of Civil Engineering, University College Dublin, Belfield, Dublin 4, Ireland.
| | - Michela Langone
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123, Italy.
| | - Gianni Andreottola
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123, Italy.
| | - Laura Bruni
- Agenzia per la Depurazione, Autonomous Province of Trento, Via Gilli 3, 38121 Trento, Italy.
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Investigation on the Effect of Structural Parameters on Cavitation Characteristics for the Venturi Tube Using the CFD Method. WATER 2019. [DOI: 10.3390/w11102194] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The venturi tube is a special kind of pipe which has been widely applied in many fields. Cavitation is one of the most important research issues for the Venturi tube. Hence, three key structural parameters (contraction angle, diffusion angle and contraction ratio) were selected to investigate the influence of different factors on cavitation characteristics, using the computational fluid dynamics (CFD) method. A series of experiments for measuring the relationship between differential pressure and flow rate were carried out to verify the accuracy of the simulation method. Results showed that the simulation results had a high accuracy and the numerical method was feasible. The average vapor volume fraction of cross-section from the throat in the axial direction increased with increasing contraction angle. The cavity length increased with increasing contraction angle. The average volume fraction in the diffusion section rapidly decreased with increasing diffusion angle. The diffusion angle had no significant effect on the cavitation characteristics in the throat section and had a significant influence in the diffusion section. The average vapor volume fraction increased with decreasing contraction ratio. The contraction ratio had no significant effect on the cavity length under the same differential pressure. The average vapor volume fraction increased with decreasing contraction ratio. However, the variation in the throat section was less than the diffusion section. Under the same inlet and outlet pressure, the cavity lengths for different contraction ratios were basically the same, which indicated that the contraction ratio had no significant effect on the cavity length.
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Pre-treatments to enhance the biodegradability of waste activated sludge: Elucidating the rate limiting step. Biotechnol Adv 2018; 36:1434-1469. [DOI: 10.1016/j.biotechadv.2018.06.001] [Citation(s) in RCA: 134] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 05/09/2018] [Accepted: 06/03/2018] [Indexed: 11/17/2022]
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Cai M, Hu J, Lian G, Xiao R, Song Z, Jin M, Dong C, Wang Q, Luo D, Wei Z. Synergetic pretreatment of waste activated sludge by hydrodynamic cavitation combined with Fenton reaction for enhanced dewatering. ULTRASONICS SONOCHEMISTRY 2018; 42:609-618. [PMID: 29429709 DOI: 10.1016/j.ultsonch.2017.11.046] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 11/24/2017] [Accepted: 11/29/2017] [Indexed: 05/12/2023]
Abstract
The dewatering of waste activated sludge by integrated hydrodynamic cavitation (HC) and Fenton reaction was explored in this study. We first investigated the effects of initial pH, sludge concentration, flow rate, and H2O2 concentration on the sludge dewaterability represented by water content, capillary suction time and specific resistance to filtration. The results of dewatering tests showed that acidic pH and low sludge concentration were favorable to improve dewatering performance in the HC/Fenton system, whereas optimal flow rate and H2O2 concentration applied depended on the system operation. To reveal the synergism of HC/Fenton treatment, a suite of analysis were implemented: three-dimensional excitation emission matrix (3-DEEM) spectra of extracellular polymeric substances (EPS) such as proteins and polysaccharides, zeta potential and particle size of sludge flocs, and SEM/TEM imaging of sludge morphology. The characterization results indicate a three-step mechanism, namely HC fracture of different EPS in sludge flocs, Fenton oxidation of the released EPS, and Fe(III) re-flocculation, that is responsible for the synergistically enhanced sludge dewatering. Results of current study provide a basis to improve our understanding on the sludge dewatering performance by HC/Fenton treatment and possible scale-up of the technology for use in wastewater treatment plants.
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Affiliation(s)
- Meiqiang Cai
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China.
| | - Jianqiang Hu
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Guanghu Lian
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Ruiyang Xiao
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China
| | - Zhijun Song
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Micong Jin
- Key Laboratory of Health Risk Appraisal for Trace Toxic Chemicals of Zhejiang Province, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010, China; Ningbo Key Laboratory of Poison Research and Control, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010, China
| | - Chunying Dong
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Quanyuan Wang
- Hangzhou Academy of Environmental Sciences, Hangzhou 310018, China
| | - Dewen Luo
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Zongsu Wei
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China; The Wolfson Faculty of Chemical Engineering, Technion-Israel Institute of Technology, Technion City, Haifa 32000, Israel.
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Langone M, Soldano M, Fabbri C, Pirozzi F, Andreottola G. Anaerobic Digestion of Cattle Manure Influenced by Swirling Jet Induced Hydrodynamic Cavitation. Appl Biochem Biotechnol 2017; 184:1200-1218. [DOI: 10.1007/s12010-017-2612-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 09/19/2017] [Indexed: 10/18/2022]
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Mancuso G, Langone M, Andreottola G. A swirling jet-induced cavitation to increase activated sludge solubilisation and aerobic sludge biodegradability. ULTRASONICS SONOCHEMISTRY 2017; 35:489-501. [PMID: 27838222 DOI: 10.1016/j.ultsonch.2016.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 10/20/2016] [Accepted: 11/03/2016] [Indexed: 05/07/2023]
Abstract
In this work, a modified swirling jet induced hydrodynamic cavitation (HC) has been used for the pre-treatment of excess sludge. In order to both improve the HC treatment efficiencies and reduce the energy consumption, the effectiveness of the HC reactor on sludge disintegration and on aerobic biodegradability has been investigated at different operating conditions and parameters, such as temperature, inlet pressure, sludge total solid (TS) content and reactor geometry. The inlet pressure was related to the flow velocity and pressure drop. The best results in terms of sludge solubilisation were achieved after 2h of HC treatment, treating a 50.0gTSL-1 and using the three heads Ecowirl system, at 35.0°C and 4.0bar. Chemical and respirometric tests proved that sludge solubilisation and aerobic biodegradability can be efficiently enhanced through HC pre-treatment technique. At the optimum operating conditions, the specific supplied energy has been varied from 3276 to 12,780kJkgTS-1 in the HC treatment, by increasing the treatment time from 2 to 8 h, respectively. Low endogenous decay rates (bH) were measured on the excess sludge at low specific supplied energy, revealing that only an alteration in floc structure was responsible for the sludge solubilisation. On the contrary, higher bH values were measured at higher specific supplied energy, indicating that the sludge solubilisation was related to a decreasing biomass viability, as consequence of dead cells and/or disrupted cells (cell lysis).
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Affiliation(s)
- Giuseppe Mancuso
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123, Italy.
| | - Michela Langone
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123, Italy.
| | - Gianni Andreottola
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123, Italy.
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Hwang BK, Son HS, Kim JH, Ahn CH, Lee CH, Song JY, Ra YH. Decomposition of excess sludge in a membrane bioreactor using a turbulent jet flow ozone contactor. J IND ENG CHEM 2010. [DOI: 10.1016/j.jiec.2010.03.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Hirooka K, Asano R, Yokoyama A, Okazaki M, Sakamoto A, Nakai Y. Reduction in excess sludge production in a dairy wastewater treatment plant via nozzle-cavitation treatment: case study of an on-farm wastewater treatment plant. BIORESOURCE TECHNOLOGY 2009; 100:3161-6. [PMID: 19246193 DOI: 10.1016/j.biortech.2009.01.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Revised: 01/08/2009] [Accepted: 01/11/2009] [Indexed: 05/15/2023]
Abstract
Nozzle-cavitation treatment was used to reduce excess sludge production in a dairy wastewater treatment plant. During the 450-d pilot-scale membrane bioreactor (MBR) operation, when 300 l of the sludge mixed liquor (1/10 of the MBR volume) was disintegrated per day by the nozzle-cavitation treatment with the addition of sodium hydrate (final concentration: 0.01% W/W) and returned to the MBR, the amount of excess sludge produced was reduced by 80% compared with that when sludge was not disintegrated. On the basis of the efficiency of CODCr removal and the ammonia oxidation reaction, it was concluded that the nozzle-cavitation treatment did not have a negative impact on the performance of the MBR. The estimation of the inorganic material balance showed that when the mass of the excess sludge was decreased, the inorganic content of the activated sludge increased and some part of the inorganic material was simultaneously solubilized in the effluent.
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Affiliation(s)
- Kayako Hirooka
- Laboratory of Sustainable Environmental Biology, Graduate School of Agricultural Science, Tohoku University, Japan.
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