scholarly journals Simulation for Sludge Flocculation I: Brownian Dynamic Simulation for Perikinetic Flocculation of Charged Particle

2012 ◽  
Vol 2012 ◽  
pp. 1-17
Author(s):  
Linshuang Liu ◽  
Guolu Yang ◽  
Minghui Yu
Keyword(s):  
Electrostatic Force ◽  
Radius Of Gyration ◽  
Brownian Dynamic ◽  
Drying Process ◽  
Floc Structure ◽  
Simulation Based ◽  
Primary Particles ◽  
High Turbidity ◽  
Sludge Drying ◽  
Original Cell

To investigate sludge drying process, a numerical simulation based on Brownian dynamic for the floc with uncharged and charged particles was conducted. The Langevin equation is used as dynamical equation for tracking each particle in a floc. An initial condition and periodic boundary condition which well conformed to reality is used for calculating the floc growth process. Each cell consists of 1000 primary particles with diameter 0.1 ∼ 4 μm. Floc growth is related to the thermal force and the electrostatic force. The electrostatic force on a particle in the simulation cell is considered as the sum of electrostatic forces from other particles in the original cell and its replicate cells. It is assumed that flocs are charged with precharged primary particles in dispersion system by ionization. By the analysis of the simulation figures, on one hand, the effects of initial particle size and sludge density on floc smashing time, floc radius of gyration, and fractal dimension were discussed. On the other hand, the effects of ionization on floc smashing time and floc structure were presented. This study has important practical value in the high-turbidity water treatment, especially for sludge drying.

Three-Dimensional Simulation for Perikinetic Flocculation of Fine Sediment under the Ionization in Still Water

2011 ◽  
Vol 356-360 ◽  
pp. 2282-2290
Author(s):  
Lin Shuang Liu ◽  
Xin Luo ◽  
Guo Lu Yang ◽  
Ming Hui Yu
Keyword(s):  
Electrostatic Force ◽  
Three Dimensional ◽  
Fine Sediment ◽  
Radius Of Gyration ◽  
Brownian Dynamic ◽  
System A ◽  
Simulation Based ◽  
Dimensional Simulation ◽  
Original Cell ◽  
Random Variation

A simulation based on Brownian dynamic for perikinetic flocculation of fine sediment under the ionization is presented. The Langevin equation is used as dynamical equation for tracking each particle making up a floc. Monte Carlo method was used for simulate random variation in particle movement. An initial condition and periodic boundary condition which conformed to reality well is used for calculation. In each cell 1000 particles of 10𝝁 m, 15𝝁m, 20𝝁m, 25𝝁m, 30𝝁m in diameter were served as primary particles. Floc growth is based on the thermal force and the electrostatic force. The electrostatic force on a particle in the simulation cell is considered as a sum of the electrostatic force from other particles in the original cell. The particles are supposed to be motion with uncharged and charged state in dispersion system. A comparison of the initial flocculent time and smashing time in sludge density 1010kg/m3, 1025 kg/m3, 1050 kg/m3, 1075 kg/m3, 1100 kg/m3were present to show the effect of it on floc growth. The increase of sludge density deferred the flocculation rate. To study morphological shape of floc, the radius of gyration was revealed under different situations. On one hand the radius of gyration presented random variation with uncharged particle, On the other hand, the radius of gyration increases gradually with the increase of polar electrical charges on primal particle. Moreover, the morphological shape for the charged floc was more open than that of unchanged state. Finally, a series of experimental results are present, which is coincide with model well.

Masking agent efficiency on odor removal from WWTP sludge drying process

2018 ◽  
Author(s):  
F. Rousseille ◽  
A. Ventura
Keyword(s):  
Control Unit ◽  
Drying Process ◽  
Odor Control ◽  
Odor Concentration ◽  
Odor Removal ◽  
Masking Agents ◽  
Last Stage ◽  
Foul Odor ◽  
Sludge Drying ◽  
Dynamic Olfactometry

Abstract A study was executed in 2016 to determine the efficiency of two different neutralizers on odor perception from a sludge drying process. One of the products was injected by fogging system at the inlet of the odor control unit while the other was added directly to the washing solution of the last stage of the odor control unit, according to supplier recommendations. Performance evaluations encompassed complementary approaches including both sensorial analyses and analytical measures. Odor analyses were performed via dynamic olfactometry according to European Standard EN 13725 coupled with hedonic tone approach according to VDI 3882. Additional analyses on VOC emissions were conducted using gas chromatography screening. In parallel, several odor panels composed of site operators and plant neighbors carried out observations on the WWTP and its perimeter. The main conclusions of this study illustrates: • Only one test leads to a reduction of the odor concentration at the stack, • Overall, neither of the two masking agents significantly reduce the odor concentration at the stack, • The addition of masking agent seems to increase foul odor persistency, • The local odor panel observed no significant improvement in odor reduction within the environment around the WWTP.

scholarly journals Nitrification in Scrubber-Washed Wastewater of Sludge Drying Process by Expanded-Bed Activated Carbon Reactor.

1995 ◽  
Vol 18 (6) ◽  
pp. 489-498
Author(s):  
Fumitake NISHIMURA ◽  
Isao SOMIYA ◽  
Hiroshi TSUNO ◽  
Hideki IWABU
Keyword(s):  
Activated Carbon ◽  
Drying Process ◽  
Expanded Bed ◽  
Sludge Drying

Modelling Agglomeration and the Fluid Dynamic Behaviour of Agglomerates

2011 ◽  
Author(s):  
S. Stu¨bing ◽  
M. Dietzel ◽  
M. Sommerfeld
Keyword(s):  
Fractal Dimension ◽  
Drag Coefficient ◽  
Cross Section ◽  
Cross Sections ◽  
Primary Particle ◽  
Radius Of Gyration ◽  
Structure Model ◽  
Collision Model ◽  
Primary Particles ◽  
The Cross

For modeling agglomeration processes in the frame of the Lagrangian approach, where the particles are treated as point masses, an extended structure model was developed. This model provides not only information on the number of primary particles in the agglomerate, but also on the geometrical distension of the agglomerates. These are for example the interception diameter, the radius of gyration, the fractal dimension and the porosity of the agglomerate using the convex hull. The question however arises now, which is the proper agglomerate cross-section for the calculation of the drag force. In order to find an answer, the Lattice-Boltzmann-Method (LBM) was applied for simulating the flow about fixed agglomerates of different morphology and number of primary particles involved. From these simulations the drag coefficient was determined using different possible cross-sections of the agglomerate. Numerous simulations showed that the cross-section of the convex hull yields a drag coefficient which is almost independent on the structure of the agglomerate if they have the same cross-sectional area in flow direction. Using the cross-section of the volume equivalent sphere showed a very large scatter in the simulated drag coefficient. This information was accounted for in the Lagrangian agglomeration model. The basis of modeling particle collisions and possible agglomeration was the stochastic inter-particle collision model accounting for the impact efficiency. The possibility of particle sticking was based on a critical velocity determined from an energy balance which accounts for dissipation and the van der Waals adhesion. If the instantaneous relative velocity between the particles is smaller than this critical velocity agglomeration occurs. In order to allow the determination of the agglomerate structure reference vectors are stored between a reference particle and all other primary particles collected in the agglomerate. For describing the collision of a new primary particle with an agglomerate the collision model was extended in order to determine which primary particle in the agglomerate is the collision partner. For demonstrating the capabilities of the Lagrangian agglomerate structure model the dispersion and collision of small primary particles in a homogeneous isotropic turbulence was considered. From these calculations statistics on the properties of the agglomerates were made, e.g. number of primary particles, radius of gyration, porosity, sphericity and fractal dimension. Finally, the dispersion of particles in vertical grid turbulence was calculated by the Lagrangian approach. For one selected model agglomerate, dispersion calculations were performed with different possible characteristic cross-sections of the agglomerate. These calculations gave a deviation of the mean square dispersion of up to 20% after a dispersion time of 0.4 seconds for the different cross-sections. This demonstrates that a proper selection of the cross-section is essential for calculating agglomerate motion in turbulent flows.

Small-angle x-ray scattering studies of early-stage colloid formation by thermohydrolytic polymerization of aqueous zirconyl salt solutions

1999 ◽  
Vol 14 (1) ◽  
pp. 103-113 ◽  
Author(s):  
Michael Z-C. Hu ◽  
Jason T. Zielke ◽  
J-S. Lin ◽  
Charles H. Byers
Keyword(s):  
Small Angle ◽  
Elevated Temperatures ◽  
Early Stage ◽  
Radius Of Gyration ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Primary Particles ◽  
Colloid Formation ◽  
Ray Scattering

Early-stage processes involving the polymerization of zirconium species in aqueous solutions at elevated temperatures (∼100 °C) as well as colloid formation were studied. Small-angle x-ray scattering (SAXS) data were analyzed via Guinier, “longrods,” and Porod plots to determine particle growth kinetics and morphology. Our SAXS data suggest that zirconium tetramers and octamers polymerize into larger clusters and elongated-rod-(or needle)-shaped primary particles, which have a length of a few nanometers and a radius of gyration of cross section between 4 and 5 Å. Cube-shaped particles are aggregates of the needlelike primary particles. The transition from zirconium tetramer to a colloidal sol particle follows a mass-fractal growth (1 < fractal dimension, D <3)

Sewage sludge drying process integration with a waste-to-energy power plant

2015 ◽  
Vol 42 ◽  
pp. 159-165 ◽  
Author(s):  
A. Bianchini ◽  
L. Bonfiglioli ◽  
M. Pellegrini ◽  
C. Saccani
Keyword(s):  
Power Plant ◽  
Sewage Sludge ◽  
Process Integration ◽  
Waste To Energy ◽  
Drying Process ◽  
Sludge Drying

scholarly journals Investigation of the effects of temperature and sludge characteristics on odors and VOC emissions during the drying process of sewage sludge

2015 ◽  
Vol 72 (4) ◽  
pp. 543-552 ◽  
Author(s):  
Wenjie Ding ◽  
Lin Li ◽  
Junxin Liu
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Wastewater Treatment Plants ◽  
Scientific Data ◽  
Gas Chromatography Mass Spectrometry ◽  
Drying Process ◽  
Drying Temperature ◽  
Volatile Organic ◽  
Sludge Drying ◽  
Total Volatile Organic Compounds

Sludge drying is a necessary step for sludge disposal. In this study, sludge was collected from two wastewater treatment plants, and dried at different temperatures in the laboratory. The emission of odor and total volatile organic compounds (TVOCs) during the sludge drying process were determined by an online odor monitoring system. The volatile organic compounds (VOCs) in off-gas were analyzed by gas chromatography–mass spectrometry. Results showed that sludge with 30% moisture content could be obtained in 51 minutes under drying temperature 100 °C but only within 27 minutes under 150 °C. Concentration of odor, TVOCs, sulfur-containing compounds (SCCs), and amines were changed with drying temperature and sludge sources. The maximum concentration of odor, TVOCs, SCCs, and amines were 503.13 ppm, 3.01 ppm, 8.15 ppm, and 11.27 ppm, respectively, at drying temperature 100 °C. These values reached 1,250.79, 8.10, 53.51, and 37.80 ppm when sludge dried at 150 °C. Odor concentration had a close relationship with emission of SCCs, amines, and TVOCs. The main VOCs released were benzene series and organic acid. Potential migration of substances in sludge was examined via analysis of off-gas and condensate, aiming to provide scientific data for effective sludge treatment and off-gas control.

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