Large Eddy Simulations of Microorganism Destruction by Peracetic Acid in
Wastewater Treatment
Wangshu
1Department
1
Wei ,
Bakhtier
1
Farouk ,
Charles N.
2
Haas ,
Philip
3
Block
of Mechanical Engineering and Mechanics, 2Department of Civil, Architectural and Environmental Engineering, Drexel University, 3PeroxyChem, Philadelphia, PA
Abstract
Computational Fluid Dynamics (CFD) Models of Injector and Reactor
Injector
A computational fluid dynamic model of the mixing and
disinfection characteristics of peracetic acid (PAA) in a
wastewater treatment pilot facility is developed. The fluid
dynamics of the spatial and temporal behaviors of mixing of PAA
Reactor
A 2-inch-diameter pipe has a ¼-inch-diameter injector which injecting PAA
into the pipe at a very slow speed(~0.001m/s).
Total length is 5 meters.
and the associated disinfection processes past the injector are
studied by the large eddy simulation (LES) technique. LES is
• 12-inch OD PVC pipe, 90 ft. long
• 3 × 180° turns to fit on a trailer
• Each turn has two 90° bends and one 19-inch
straight section.
• Over all dimensions: 22 × 4 × 4 ft.
• Inlet velocity~0.02m/s
• A ¼ in thick Baffle placed 4 inch from inlet
considered very attractive for predicting scalar mixing and
chemical reactions in turbulent reacting flows.
3-D Meshing of injector
Same porosity
Our Goal
Real baffle:
• 12-inch-diameter
• ¼-inch thick plate
• 72X0.5-inch-diameter holes
CFD
simulation with
LES model
3-D CFD
modeling
Simplified model:
• 12-inch-length square
• 15X1-inch-length
holes
Concentration of PAA at exit
Validation with
experimental
data
Develop a
metamodel
based on ANN
Concentration of PAA at different time
Metamodel Based on Neural Network
3-D Meshing of reactor
Artificial Neural Network(ANN)
Why Preacetic Acid?
•
•
•
•
• Data flows through neurons with various
weights and biases
• Each “hidden” neuron represents a
• It is an organic molecule with harmless organic by-products
(acetic acid).
CH3 CO2 OH
• Structure inspired by neuron connections
in animals
Formula: 𝐂𝐇𝟑 𝐂𝐎𝟐 𝐎𝐇
Density: 1.04 g/cm³
Boiling point: 77°F (25°C)
Melting point: 32°F (0°C)
H2 O
Meshing near the Baffle region
CH3 COOH + H2 O2
• It has a stronger oxidation capacity than chlorine.
nonlinear transfer function (generally
hyperbolic tangent)
• Network is “trained” by optimizing the
weight and bias values to best fit the data
• It has a longer shelf-life than sodium hypochlorite.
Future Work
• Introduce self decay of PAA and inactivation reaction between PAA and microorganisms to this LES model
• Train metamodel with experimental data and predict the mixing and inactivation into full size reactor
• Validate the models with experimental data
Concentration of PAA at different time
Concentration of PAA at cross-section
Acknowledgement
I would like to thank my advisors, Dr. Bakhtier Farouk and Dr. Charles Haas for helping me with my project offering me
insight and advice on both CFD model and ANN based metamodel. I would also like to thank Dr. Philip Block for providing
pilot-site facility dimensions and experimental data for further study.