scholarly journals Effect of hydrodynamic breakage on floc evolution and turbidity reduction in flocculation and sedimentation processes

2021 ◽  
Author(s):  
Xinran Zhang ◽  
Jiaqi Zhu ◽  
Zhenxing Li ◽  
Junyi Li ◽  
Pengfei Ren
Keyword(s):  
Fractal Dimension ◽  
Velocity Gradient ◽  
Perforated Plate ◽  
Drinking Water Treatment ◽  
Recognition System ◽  
Turbidity Removal ◽  
Perforated Plates ◽  
Floc Size ◽  
Hydrodynamic Shear ◽  
Restructuring Process

Abstract Coagulation and sedimentation process is one of the most popular processes in drinking water treatment. Hydrodynamic breakage has a significant impact on the evolution of floc characteristic and the efficiency of turbidity removal. In this work, the effects of hydrodynamic breakage on floc size, fractal dimension, and floc morphology were investigated with an in-situ recognition system. The experiments were conducted in a continuous flocculation and sedimentation reactor equipped with perforated plates to provide different hydrodynamic breakage conditions. The experimental results indicated that the hydrodynamic conditions significantly influenced the floc destabilization and restructuring processes. A low hydrodynamic shear forces provided by P1 led to the increase of both bigger sized flocs but accompanied with small particles (0–10 μm). Excessive velocity gradient provided by P3 produced smaller and looser flocs. An appropriate velocity gradient (i.e., the flow velocity through the perforated plate P2 at 18.9 × 10−3m s−1) was conducive for the formation of larger and more compact structures, with higher average floc size and fractal dimension. This flocculation condition in turn resulted in effective improvements in the turbidity removal efficiency. Floc evolution models were described based on the mechanism of the breakage and restructuring process.

scholarly journals Use of Aloe vera as an Organic Coagulant for Improving Drinking Water Quality

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2024
Author(s):  
Abderrezzaq Benalia ◽  
Kerroum Derbal ◽  
Amel Khalfaoui ◽  
Raouf Bouchareb ◽  
Antonio Panico ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Suspended Solids ◽  
Aluminum Sulfate ◽  
Aloe Vera ◽  
Drinking Water Treatment ◽  
Water Turbidity ◽  
Turbidity Removal ◽  
Maximum Turbidity ◽  
Optimal Ph

The coagulation–flocculation–sedimentation process is widely used for removal of suspended solids and water turbidity reduction. The most common coagulants used to conduct this process are aluminum sulfate and ferric sulfate. In this paper, the use of Aloe vera as a natural-based coagulant for drinking water treatment was tested. The bio-coagulant was used in two different forms: powder as well as liquid; the latter was extracted with distilled water used as a solvent. The obtained results showed that the use of the natural coagulant (Aloe vera) in both powder (AV-Powder) and liquid (AV-H2O) forms reduced the water turbidity at natural pH by 28.23% and 87.84%, respectively. Moreover, it was found that the use of the two previous forms of bio-coagulant for drinking water treatment had no significant influence on the following three parameters: pH, alkalinity, and hardness. The study of the effect of pH on the process performance using Aloe vera as a bio-coagulant demonstrated that the maximum turbidity removal efficiency accounted for 53.53% and 88.23% using AV-Powder and AV-H2O, respectively, at optimal pH 6.

High Speed Flow through Perforated Plates

1960 ◽  
Vol 64 (590) ◽  
pp. 103-105
Author(s):  
P. G. Morgan
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Perforated Plate ◽  
Wire Mesh ◽  
Flow Conditions ◽  
High Speed Flow ◽  
Perforated Plates ◽  
Speed Flow ◽  
Flow Through ◽  
Points Of View

The flow through porous screens has been widely studied from both the theoretical and experimental points of view. The most widely used types of screen are the wire mesh and the perforated plate, and the majority of the literature has been concerned with the former. Several attempts have been made to correlate the parameters governing the flow through such screens, i.e. the pressure drop, the flow conditions and the geometry of the mesh.

scholarly journals THE STUDY OF ACOUSTIC CHARACTERISTICS OF THE PERFORATED AND HOMOGENOUS PLATES WITH SIMILAR GEOMETRICAL DIMENSIONS

Akustika ◽  
2019 ◽  
Vol 32 ◽  
pp. 79-82
Author(s):  
Valery Kirpichnikov ◽  
Lyudmila Drozdova ◽  
Alexei Koscheev ◽  
Ernst Myshinsky
Keyword(s):  
Resonant Frequency ◽  
Acoustic Radiation ◽  
Perforated Plate ◽  
Acoustic Characteristics ◽  
Resonant Frequencies ◽  
Perforated Plates ◽  
Resonance Frequencies ◽  
Flexural Vibrations ◽  
Geometrical Dimensions

The resonance frequencies of the flexural vibrations, input vibration excitability and acoustic radiation of the homogeneous and perforated plates were investigated. It is established that the average reduction range of the lower resonant frequency of flexural vibrations of the tested plates with the holes virtually coincides with the predictive estimate. The levels of the input vibration excitability of the perforated plate at the lower resonant frequencies exceeded the levels at the corresponding frequencies of the homogeneous plates greater than the calculated value. The levels of resonance acoustic radiation of the perforated plate were significantly less than of the homogeneous one.

scholarly journals Silylated Thiol-Containing Cellulose Nanofibers as a Bio-Based Flocculation Agent for Ultrafine Mineral Particles of Chalcopyrite and Pyrite

2021 ◽  
Author(s):  
Ana Luiza Coelho Braga de Carvalho ◽  
Feliciana Ludovici ◽  
Daniel Goldmann ◽  
André Carlos Silva ◽  
Henrikki Liimatainen
Keyword(s):  
Ultrafine Particles ◽  
Fine Particles ◽  
Cellulose Nanofibers ◽  
Aqueous Alkaline Medium ◽  
Selective Flocculation ◽  
Turbidity Removal ◽  
Floc Size ◽  
Mineral Particles ◽  
Tailing Ponds ◽  
Anionic Polyacrylamide

AbstractA considerable amount of very fine particles can be found, e.g., stored in tailing ponds, and they can include valuable or hazardous minerals that have the potential to be recovered. Selective flocculation, i.e., the formation of larger aggregates from specific minerals, offers a promising approach to improve the recovery of ultrafine particles. This study focuses on the use of a new bio-based flocculation agent made of silylated cellulose nanofibers containing a thiol-functional moiety (SiCNF). Flocculation was performed in separated systems of ultrafine mineral dispersions of pyrite, chalcopyrite, and quartz in aqueous alkaline medium. The flocculation performance of SiCNF was addressed in terms of the turbidity reduction of mineral dispersions and the floc size, and the results were compared with the performance of a commercial anionic polyacrylamide. SiCNF exhibited a turbidity removal efficiency of approximately 90%–99% at a concentration of 4000–8000 ppm with chalcopyrite and pyrite, whereas the turbidity removal of quartz suspension was significantly lower (a maximum of approximately 30%). The sulfide particles formed flocs with a size of several hundreds of micrometers. The quartz in turn did not form any visible flocs, and the dispersion still had a milky appearance after dosing 12,000 ppm of the flocculant. These results open a promising path for the investigation of SiCNF as a selective flocculation agent for sulfide minerals. Graphical Abstract

The Aerodynamic Drag of Perforated Plates at Zero Incidence

1958 ◽  
Vol 62 (568) ◽  
pp. 301-303 ◽  
Author(s):  
P. Minton ◽  
J. R. D. Francis
Keyword(s):  
Pipe Flow ◽  
Aerodynamic Drag ◽  
Perforated Plate ◽  
Perforated Plates ◽  
Drag Forces ◽  
Flow Experiments

Perforated Plates have been used at large angles of incidence to produce drag forces and evidence on their properties has been published by de Bray. Less appears to be known about the drag forces on such surfaces at zero incidence, although they are usually considered to be aerodynamically rough. This has been confirmed by Ambrose, who carried out pipe flow experiments using perforated liners which fitted tightly in the bore of a pipe. Perforated plates used in this way do not allow flow completely through them and give “pitted” surfaces. If a perforated plate is mounted so that it is possible for cross flows to occur between the main flows on both sides of the plate the drag forces on it may be affected, and in this case the perforations will be referred to as “holes.”

Vibration Characteristics of a Perforated Plate Immersed in Fluid

2012 ◽  
Author(s):  
Tomohiro Ito ◽  
Atsuhiko Shintani ◽  
Chihiro Nakagawa
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Damping Ratio ◽  
Thermal Power ◽  
Perforated Plate ◽  
Vibration Characteristics ◽  
Chemical Plants ◽  
Perforated Plates ◽  
Stiffness Reduction ◽  
Test Models

Perforated plates are used in many mechanical structures in thermal power plants, nuclear power plants, or chemical plants etc. Cylindrical structures made by the perforated plates are also found in many places. However, vibration characteristics of the structures made by perforated plates are not fully clarified, especially for the structures immersed in liquid. The stiffness of the structures becomes smaller than that of ones made by simple plates with no holes, while the mass of the structures also becomes smaller. According to the balance between the stiffness reduction and mass reduction, natural frequencies will be decided. Moreover, added mass and added damping effects are very large in liquid, and are thought to largely change due to holes. In this study, as a fundamental step, a perforated plate is treated. The vibration characteristics such as natural frequency and damping ratio are studied for various hole numbers or various opening ratios by both numerical simulations and simple test models. Vibration tests are conducted in liquid as well as in air.

scholarly journals Occurrence and Succession of Bacterial Community in O3/BAC Process of Drinking Water Treatment

2019 ◽  
Vol 16 (17) ◽  
pp. 3112 ◽  
Author(s):  
Sheng Dong ◽  
Lijun Liu ◽  
Yuxiu Zhang ◽  
Fajun Jiang
Keyword(s):  
Drinking Water ◽  
Activated Carbon ◽  
Bacterial Community ◽  
Dissolved Oxygen ◽  
Chemical Oxygen Demand ◽  
Bacterial Communities ◽  
Oxygen Demand ◽  
Drinking Water Treatment ◽  
Turbidity Removal ◽  
N Removal

In the drinking water industry, a common advanced treatment process is comprised of treatment with ozone, followed by biological-activated carbon (O3/BAC). However, the bacterial community formation and succession procedures associated with activated carbon have rarely been reported. In this study, the dynamics of bacterial communities at three different depths were investigated using a pilot-scale O3/BAC filter. The average chemical oxygen demand (CODMn), turbidity removal and dissolved oxygen (DO) consumption rate of the filter were 26.43%, 16.57% and 16.4% during the operation period, respectively. Bacterial communities dominated by proteobacteria and Bacteroidetes attached on activated carbon were determined by polymerase chain reaction-density gradient gel electrophoresis (PCR-DGGE). Principal component analysis (PCA) revealed that the compositions and structures of bacterial communities in different layers clustered after fluctuation. A redundancy analysis (RDA) indicated that Ramlibacter henchirensis was positively correlated to chemical oxygen demand (CODMn) removal and nitrate-N removal, and Georgfuchsia toluolica also showed a positive correlation with CODMn removal. Aquabacterium parvum and Phaeobacterium nitratireducens were positively-correlated with turbidity removal. Pedobacter glucosidilyticus and Pseudomonas sp. were associated with high dissolved oxygen (DO) consumption. These results provide insight into the succession characteristics of the bacterial community of O3/BAC treatment and the interactions of the bacterial community with filter operation performance.

scholarly journals An Experimentally Validated Numerical Modeling Technique for Perforated Plate Heat Exchangers

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
M. J. White ◽  
G. F. Nellis ◽  
S. A. Klein ◽  
W. Zhu ◽  
Y. Gianchandani
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Numerical Model ◽  
Heat Exchangers ◽  
Perforated Plate ◽  
Plate Heat Exchanger ◽  
Internal Temperature ◽  
Perforated Plates ◽  
Axial Conduction ◽  
Plate Heat

Cryogenic and high-temperature systems often require compact heat exchangers with a high resistance to axial conduction in order to control the heat transfer induced by axial temperature differences. One attractive design for such applications is a perforated plate heat exchanger that utilizes high conductivity perforated plates to provide the stream-to-stream heat transfer and low conductivity spacers to prevent axial conduction between the perforated plates. This paper presents a numerical model of a perforated plate heat exchanger that accounts for axial conduction, external parasitic heat loads, variable fluid and material properties, and conduction to and from the ends of the heat exchanger. The numerical model is validated by experimentally testing several perforated plate heat exchangers that are fabricated using microelectromechanical systems based manufacturing methods. This type of heat exchanger was investigated for potential use in a cryosurgical probe. One of these heat exchangers included perforated plates with integrated platinum resistance thermometers. These plates provided in situ measurements of the internal temperature distribution in addition to the temperature, pressure, and flow rate measured at the inlet and exit ports of the device. The platinum wires were deposited between the fluid passages on the perforated plate and are used to measure the temperature at the interface between the wall material and the flowing fluid. The experimental testing demonstrates the ability of the numerical model to accurately predict both the overall performance and the internal temperature distribution of perforated plate heat exchangers over a range of geometry and operating conditions. The parameters that were varied include the axial length, temperature range, mass flow rate, and working fluid.

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