Population balance modelling of activated sludge flocculation: Investigating the size dependence of aggregation, breakage and collision efficiency

2006 ◽  
Vol 61 (1) ◽  
pp. 63-74 ◽  
Author(s):  
A. Ding ◽  
M.J. Hounslow ◽  
C.A. Biggs
Keyword(s):  
Activated Sludge ◽  
Size Dependence ◽  
Population Balance ◽  
Collision Efficiency

scholarly journals Simulation of Floc Size Distribution in Flocculation of Activated Sludge Using Population Balance Model with Modified Expressions for the Aggregation and Breakage

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Zhenliang Li ◽  
Peili Lu ◽  
Daijun Zhang ◽  
Fuzhong Song
Keyword(s):  
Activated Sludge ◽  
Size Distribution ◽  
Velocity Gradient ◽  
Population Balance ◽  
Balance Model ◽  
Population Balance Model ◽  
Collision Efficiency ◽  
Volume Percentage ◽  
Floc Size ◽  
Breakage Rate

The floc size distribution of activated sludge was simulated successfully by population balance model in the previous study (Population Balance Model and Calibration Method for Simulating the Time Evolution of Floc Size Distribution of Activated Sludge Flocculation. Desalination and Water Treatment, 67, 41-50). However, nonignorable errors exist in the simulation for the volume percentage of large flocs. This paper describes the application of a modified population balance model in the simulation of the time evolution of floc size distribution in activated sludge flocculation process under shear-induced conditions. It was found that the application of modified size dependent collision efficiency, modified breakage rate expression by assuming a maximum value, and binominal daughter-particles distribution function could improve the population balance model for activated sludge flocculation and successfully predict the dynamic changes in volume percentage distribution and mean floc size of activated sludge under different shear conditions. The results demonstrate that the maximum breakage rate was independent on the velocity gradient, and both the collision efficiency and breakage rate coefficient show a power-law relationship with the average velocity gradient; the former decreases while the latter increases with the rise of the average velocity gradient. These findings would help to understand the dynamics of activated sludge flocculation.

Modelling the Activated Sludge Flocculation Process Using Population Balance Model (PBM)

2012 ◽  
Vol 610-613 ◽  
pp. 1372-1376 ◽  
Author(s):  
Zhen Liang Li
Keyword(s):  
Activated Sludge ◽  
Population Balance ◽  
Balance Model ◽  
Efficiency Coefficient ◽  
Collision Efficiency ◽  
Mean Size ◽  
Shear Condition ◽  
Best Fit ◽  
Flocculation Process ◽  
Selection Of

This paper describes the application of population balance models to activated sludge flocculation process. It presents the development and selection of appropriate expressions for aggregation and breakage kinetics within the population balance framework to describe the evolution of mean size and steady state distribution of flocs under shear conditions. A size and velocity gradient dependent collision efficiency is introduced into the aggregation expression. In the model, only 2 parameters need to be estimated: collision efficiency coefficient and the breakage frequency coefficient. They are obtained by the “best fit” with the experimental data, and keep unchanged under different shear condition for the same flocs. The modelling results indicate that the population balance models coupled with suitable aggregation and breakage kinetics is appropriate for describing activated sludge flocculation dynamics.

Flotation efficiency of activated sludge flocs using population balance model in dissolved air flotation

2006 ◽  
Vol 23 (2) ◽  
pp. 271-278 ◽  
Author(s):  
Heung-Joe Jung ◽  
Jae-Wook Lee ◽  
Do-Young Choi ◽  
Seong-Jin Kim ◽  
Dong-Heui Kwak
Keyword(s):  
Activated Sludge ◽  
Population Balance ◽  
Balance Model ◽  
Population Balance Model ◽  
Dissolved Air Flotation ◽  
Sludge Flocs ◽  
Air Flotation ◽  
Dissolved Air

Solving the inverse problem for aggregation in activated sludge flocculation using a population balance framework

2007 ◽  
Vol 56 (6) ◽  
pp. 95-103 ◽  
Author(s):  
I. Nopens ◽  
N. Nere ◽  
P.A. Vanrolleghem ◽  
D. Ramkrishna
Keyword(s):  
Experimental Data ◽  
Inverse Problem ◽  
Particle Size ◽  
Activated Sludge ◽  
Predictive Power ◽  
Population Balance ◽  
Model Structure ◽  
Forward Simulation ◽  
Floc Size

Many systems contain populations of individuals. Often, they are regarded as a lumped phase, which might, for some applications, lead to inadequate model predictive power. An alternative framework, Population Balance Models, has been used here to describe such a system, activated sludge flocculation in which particle size is the property one wants to model. An important problem to solve in population balance modelling is to determine the model structure that adequately describes experimentally obtained data on for instance, the time evolution of the floc size distribution. In this contribution, an alternative method based on solving the inverse problem is used to recover the model structure from the data. In this respect, the presence of similarity in the data simplifies the problem significantly. Similarity was found and the inverse problem could be solved. A forward simulation then confirmed the quality of the model structure to describe the experimental data.

Aggregate size-dependence of bacterial community separation in a full-scale membrane bioreactor plant

2020 ◽  
Vol 96 (5) ◽  
Author(s):  
Shaoqing Zhang ◽  
Bing Li ◽  
Zhong Yu ◽  
Fangang Meng
Keyword(s):  
Bacterial Community ◽  
Activated Sludge ◽  
Nutrient Removal ◽  
Species Interactions ◽  
Membrane Bioreactor ◽  
Size Dependence ◽  
Full Scale ◽  
Water Separation ◽  
Significant Difference ◽  
Activated Sludge Processes

ABSTRACT The size of bacterial aggregates can determine both nutrient removal and sludge/water separation in activated sludge processes. In this study, the bacterial community structures and network associations of different sized aggregates obtained from a full-scale membrane bioreactor plant over a one-year period were investigated. Our results showed that biodiversity of larger sized aggregates was significantly higher than that of smaller ones and that the bacterial compositions of different sized aggregates differed significantly from each other. Bacteria related to nutrient removal (e.g. denitrification, hydrolysis and fermentation) were found to be significantly more abundant in larger aggregates than smaller ones. Network analysis revealed significant difference in species–species interactions, topological roles of individual OTU and keystone populations among different sized aggregates. Moreover, the occurrence of keystone OTUs affiliated with denitrifiers (Thermomonas) in networks of large and medium aggregates may suggest that denitrification influences bacterial interactions in large and medium aggregates. Overall, our results indicate the aggregates size-dependence of bacterial community separation in activated sludge. The current findings not only can provide guidance for process design and operation optimization, but also highlight the necessity for paying more attentions to the aggregate-based community, metabolic function and gene expression of activated sludge in future studies.

Understanding the Precipitated Calcium Carbonate Flocculation Mechanism Induced by Starch through Population Balance Modeling

2011 ◽  
Vol 236-238 ◽  
pp. 1250-1255
Author(s):  
Yi Zhou Sang ◽  
Nayef M. Al Saifi ◽  
Peter Englezos
Keyword(s):  
Calcium Carbonate ◽  
Population Balance ◽  
Energy Dissipation Rate ◽  
Balance Model ◽  
Collision Efficiency ◽  
Precipitated Calcium Carbonate ◽  
Population Balance Modeling ◽  
Flocculation Mechanism ◽  
Effects Of Temperature ◽  
Breakage Mechanism

The precipitated calcium carbonate (PCC) flocculation kinetics and floc structures induced by cationic tapioca starch were recorded by the Malvern Mastersizer 2000 (Malvern Instruments Inc, Malvern, UK). Of particular interest, a population balance model for PCC flocculation was employed to extract the flocculation constants, namely collision efficiency, magnitude of energy dissipation rate and restructuring rate. The model made an attempt to take aggregation, breakage and flocs restructuring into account simultaneously to describe the PCC flocculation by aggregation and breakage mechanism. Through a response surface methodology (RSM) involving a central composite design, the effects of temperature, polymer dosage, ionic strength, and shear rate on flocculation parameters were investigated in this paper.

scholarly journals Comparison of the Accuracy and Performance of Different Numbers of Classes in Discretised Solution Method for Population Balance Model

2016 ◽  
Vol 2016 ◽  
pp. 1-6
Author(s):  
Zhenliang Li ◽  
Zhien Zhou ◽  
Sheng Zhang ◽  
Hongqiang Jiang
Keyword(s):  
Fibonacci Sequence ◽  
Population Balance ◽  
Balance Model ◽  
Population Balance Model ◽  
Collision Efficiency ◽  
Exponential Relationship ◽  
Parameter Ratio ◽  
And Performance ◽  
Number Of Classes ◽  
Geometric Grids

One way of solving population balance model (PBM) in a time efficient way is by means of discretisation of the population property of interest. A computational grid, for example, vi+1=kvi (vi is the volume of particle in class i), could be used to classify the particles in discretisation techniques. However, there are still disagreements in the appropriate number of classes divided by the grids. In this study, the different numbers of classes for solving PBM were compared in terms of accuracy and performance to describe the particle size distribution (PSD) from the flocculation of activated sludge. It is found that the simulated PSDs are similar to the experimental data for all the geometric grids (vi+1:vi≤2), and there is no obvious difference among the values of calibrated parameter, ratio of breakage rate coefficient and collision efficiency, for each velocity gradient. However, the simulation results with less error could be obtained with larger number of classes, and more computational times, which show exponential relationship with the number of classes, are needed. Considering numerical accuracy and efficiency, the classes 35 or a geometric grid with factor 1.6, aligning with the Fibonacci sequence (vi+vi-1≈vi+1), is recommended for the particles in the size range of 5.5~1086 μm.

scholarly journals Understanding the coagulation mechanism and floc properties induced by Fe(VI) and FeCl3: population balance modeling

2021 ◽  
Author(s):  
Xinliang Liu ◽  
Hailiang Yin ◽  
Jian Zhao ◽  
Ziqi Guo ◽  
Zhen Liu ◽  
...  
Keyword(s):  
Practical Importance ◽  
Population Balance ◽  
Collision Efficiency ◽  
Population Balance Modeling ◽  
Floc Size ◽  
Coagulation Mechanism ◽  
Coagulation Kinetics ◽  
Floc Strength ◽  
Floc Properties ◽  
Positive Effect

Abstract Coagulation kinetics and floc properties are of great fundamental and practical importance in the field of water treatment. To investigate the performance of Fe(VI) and Fe(III) salt on particle coagulation, Malvern Mastersizer 2000 was employed to continuously and simultaneously monitor the kaolin floc size and structure change, and population balance modeling was used to investigate the coagulation mechanism. The results show dosage increase had positive effect on collision efficiency and floc strength and negative effect on restructure rate. Low shear rate resulted in higher collision efficiency and stronger floc. Low water temperature had a pronounced detrimental effect on coagulation kinetics. Temperature increase showed the most significant positive effect on collision efficiency, floc strength and restructure rate. The optimum pH zone for the coagulation was found to be between 6 and 8. Further pH increase lowered the collision efficiency and floc strength and increased the restructure rate. FeCl3 resulted in a larger ratio of the mass to volume of kaolin flocs (compactness) than those induced by ferrate.

scholarly journals Improving the Flocculation Performance of Clay-Based Tailings in Seawater: A Population Balance Modelling Approach

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 782
Author(s):  
Gonzalo R. Quezada ◽  
Matías Jeldres ◽  
Pedro Robles ◽  
Norman Toro ◽  
David Torres ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Goodness Of Fit ◽  
Aggregate Size ◽  
Population Balance ◽  
Magnesium Content ◽  
Balance Model ◽  
Collision Efficiency ◽  
Reflectance Measurement ◽  
Vacuum Filtration ◽  
The Impact

A population balance model described the flocculation of clay-based mining tailings in treated seawater with reduced magnesium content. For the treatment, 0.06 M of lime was added to the liquor, generating solid magnesium complexes that were subsequently removed by vacuum filtration. Magnesium content varied between 10–1440 ppm when mixing raw seawater with treated seawater. The aggregate size was analysed by the Focused Beam Reflectance Measurement (FBRM) technology. The model follows the dynamics of the aggregation-rupture and it provides a good approximation to the temporal evolution. A decrease in collision efficiency was implemented as an indicator of the polymer depletion, describing the size reduction. Lower magnesium content makes larger aggregates with a higher fractal dimension, but an increase in the concentration of clays reduces both the size of aggregates and the fractal dimension, indicating more open and porous structures, with higher permeability to the passage of fluid. The model efficiently illustrates the experimental data, with R-square (R2) greater than 0.9 and Goodness of Fit (GoF) greater than 95% in most cases, wherein the fitting parameters allowed for analysing the impact of magnesium and clays on the collision efficiency, collision frequency, and fragmentation rate. The model is predictive with few parameters, and it is potentially a powerful tool for water management optimisation.

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