New mass-based population balance model including shear rate effects: Application to struvite recovery.
Struvite (MgNH4PO4·6H2O) precipitation is a promising solution for phosphorus recovery in wastewater treatment plants. Controlled struvite precipitation can help to reduce eutrophication in the receiving waterways, fight global phosphorus scarcity and reduce operational problems generated by the unc...
| Main Authors: | , , |
|---|---|
| Format: | info:eu-repo/semantics/doctoralThesis |
| Language: | eng |
| Published: |
Servicio de Publicaciones. Universidad de Navarra
2021
|
| Subjects: | |
| Online Access: | https://hdl.handle.net/10171/59934 |
| _version_ | 1793400554593976320 |
|---|---|
| author | Elduayen-Echave, B. (Beñat) Grau-Gumbau, P. (Paloma) Sanchez-Larraona, G. (Gorka) |
| author_facet | Elduayen-Echave, B. (Beñat) Grau-Gumbau, P. (Paloma) Sanchez-Larraona, G. (Gorka) |
| author_sort | Elduayen-Echave, B. (Beñat) |
| collection | DSpace |
| description | Struvite (MgNH4PO4·6H2O) precipitation is a promising solution for phosphorus recovery in wastewater treatment plants. Controlled struvite precipitation can help to reduce eutrophication in the receiving waterways, fight global phosphorus scarcity and reduce operational problems generated by the uncontrolled precipitation of the mineral in the pipes. Due to the generated interest, the description of the precipitation process has been already included in existing wastewater treatment modelling libraries. However, following the classic wastewater treatment modelling approach, the process has been generally included as a one-step kinetic model. This one-step model type is limited for technological design and optimization purposes, as it does not include information about the mechanisms by which the precipitation occurs, nor the particle size distribution, a key variable for the performance of struvite as an effective fertilizer. Therefore, the aim of this thesis has been to upgrade existing one-step kinetic models by developing a mathematical model that could describe in detail the mechanisms occurring in struvite precipitation in order to be able to predict the resulting particle size distribution. This model is a population balance model in which hydrodynamic effects have been considered. The population balance model has been constructed according to Ceit’s plant wide model methodology, guaranteeing mass and charge balance. Therefore, it can be combined with the simulation of other unit processes used to describe wastewater treatment plants in a systematic and straightforward way. A sensitivity and collinearity analysis performed in the thesis, demonstrated that the model is coherent in its structure and valid to represent struvite precipitation processes. In order to incorporate the hydrodynamic effects to the model, results obtained in an experimental campaign where struvite precipitation was analysed under different mixing and saturation conditions in two different experimental set-ups, were used. Obtained results showed that a higher mixing intensity could be linked with a faster pH decay, an increasing particle density and lower particle size. These effects were included in the population balance model using a calibration procedure based on Bayesian Monte Carlo techniques. From the calibration procedure, new kinetic laws were proposed for struvite nucleation and growth, where the effect of the hydrodynamics had been decoupled by explicitly including the shear rate as a process variable. |
| format | info:eu-repo/semantics/doctoralThesis |
| id | oai:dadun.unav.edu:10171-59934 |
| institution | Universidad de Navarra |
| language | eng |
| publishDate | 2021 |
| publisher | Servicio de Publicaciones. Universidad de Navarra |
| record_format | dspace |
| spelling | oai:dadun.unav.edu:10171-599342022-11-24T11:20:37Z New mass-based population balance model including shear rate effects: Application to struvite recovery. Elduayen-Echave, B. (Beñat) Grau-Gumbau, P. (Paloma) Sanchez-Larraona, G. (Gorka) Population balance model. Struvite. Shear rate. Particle size distribution. Precipitation. Parameter identifiability. Struvite (MgNH4PO4·6H2O) precipitation is a promising solution for phosphorus recovery in wastewater treatment plants. Controlled struvite precipitation can help to reduce eutrophication in the receiving waterways, fight global phosphorus scarcity and reduce operational problems generated by the uncontrolled precipitation of the mineral in the pipes. Due to the generated interest, the description of the precipitation process has been already included in existing wastewater treatment modelling libraries. However, following the classic wastewater treatment modelling approach, the process has been generally included as a one-step kinetic model. This one-step model type is limited for technological design and optimization purposes, as it does not include information about the mechanisms by which the precipitation occurs, nor the particle size distribution, a key variable for the performance of struvite as an effective fertilizer. Therefore, the aim of this thesis has been to upgrade existing one-step kinetic models by developing a mathematical model that could describe in detail the mechanisms occurring in struvite precipitation in order to be able to predict the resulting particle size distribution. This model is a population balance model in which hydrodynamic effects have been considered. The population balance model has been constructed according to Ceit’s plant wide model methodology, guaranteeing mass and charge balance. Therefore, it can be combined with the simulation of other unit processes used to describe wastewater treatment plants in a systematic and straightforward way. A sensitivity and collinearity analysis performed in the thesis, demonstrated that the model is coherent in its structure and valid to represent struvite precipitation processes. In order to incorporate the hydrodynamic effects to the model, results obtained in an experimental campaign where struvite precipitation was analysed under different mixing and saturation conditions in two different experimental set-ups, were used. Obtained results showed that a higher mixing intensity could be linked with a faster pH decay, an increasing particle density and lower particle size. These effects were included in the population balance model using a calibration procedure based on Bayesian Monte Carlo techniques. From the calibration procedure, new kinetic laws were proposed for struvite nucleation and growth, where the effect of the hydrodynamics had been decoupled by explicitly including the shear rate as a process variable. La precipitación de estruvita (MgNH4PO4·6H2O) es una solución prometedora para la recuperación de fósforo en estaciones depuradoras de aguas residuales. La precipitación controlada de estruvita puede ayudar a reducir la eutrofización provocada por los vertidos de la depuradora, combatir la escasez global de fósforo y reducir los problemas operacionales generados por la precipitación incontrolada del mineral en las tuberías. Debido al interés generado, la descripción del proceso de precipitación ya se ha incluido en las librerías de modelado de tratamiento de aguas residuales existentes. Sin embargo, siguiendo el enfoque clásico de modelado de tratamiento de aguas residuales, el proceso se ha incluido generalmente con una cinética de un solo paso. Este hecho limita el uso del modelo matemático para fines de diseño y optimización de tecnologías, ya que no se consideran ni los mecanismos de precipitación ni la distribución del tamaño de partícula, siendo ésta una variable clave en el desempeño de la estruvita como fertilizante. Por lo tanto, el objetivo de esta tesis ha sido mejorar los modelos cinéticos de un paso existentes mediante el desarrollo de un modelo matemático que describe en detalle los mecanismos que ocurren en la precipitación de estruvita para poder predecir la distribución del tamaño de partícula resultante. Este modelo es un modelo de balance poblacional en el que se han considerado efectos hidrodinámicos. El modelo de balance poblacional se ha construido siguiendo la metodología de modelado integral de planta (‘Plant Wide Model’) de Ceit, garantizando el balance de masa y carga. Por lo tanto, se puede combinar con la simulación de otros procesos que ocurren en las estaciones depuradoras de aguas residuales de una manera sistemática y sencilla. Un análisis de sensibilidad y colinealidad realizado en la tesis, demostró que el modelo es coherente en su estructura y válido para representar procesos de precipitación de estruvita. Para incorporar los efectos hidrodinámicos al modelo, se utilizaron los resultados obtenidos en una campaña experimental donde se analizó la precipitación de estruvita bajo diferentes intensidades de agitación y grado de saturación. Los resultados obtenidos mostraron que una mayor intensidad de agitación podría estar relacionada con una caída más rápida del pH, un aumento del número de partículas y un menor tamaño medio de las partículas obtenidas. Estos efectos se incluyeron en el modelo de balance de población utilizando una metodología de calibración basada en inferencia bayesiana. A partir de la metodología de calibración, se propusieron nuevas leyes cinéticas para la nucleación y el crecimiento de la estruvita, donde el efecto de la hidrodinámica está desacoplado al incluir explícitamente la cizalladura como una variable de proceso. 2021-01-04T13:09:28Z 2021-01-04T13:09:28Z 2020-12 2020-12-18 info:eu-repo/semantics/doctoralThesis https://hdl.handle.net/10171/59934 eng info:eu-repo/semantics/openAccess application/pdf Servicio de Publicaciones. Universidad de Navarra |
| spellingShingle | Population balance model. Struvite. Shear rate. Particle size distribution. Precipitation. Parameter identifiability. Elduayen-Echave, B. (Beñat) Grau-Gumbau, P. (Paloma) Sanchez-Larraona, G. (Gorka) New mass-based population balance model including shear rate effects: Application to struvite recovery. |
| title | New mass-based population balance model including shear rate effects: Application to struvite recovery. |
| title_full | New mass-based population balance model including shear rate effects: Application to struvite recovery. |
| title_fullStr | New mass-based population balance model including shear rate effects: Application to struvite recovery. |
| title_full_unstemmed | New mass-based population balance model including shear rate effects: Application to struvite recovery. |
| title_short | New mass-based population balance model including shear rate effects: Application to struvite recovery. |
| title_sort | new mass-based population balance model including shear rate effects: application to struvite recovery. |
| topic | Population balance model. Struvite. Shear rate. Particle size distribution. Precipitation. Parameter identifiability. |
| url | https://hdl.handle.net/10171/59934 |
| work_keys_str_mv | AT elduayenechavebbenat newmassbasedpopulationbalancemodelincludingshearrateeffectsapplicationtostruviterecovery AT graugumbauppaloma newmassbasedpopulationbalancemodelincludingshearrateeffectsapplicationtostruviterecovery AT sanchezlarraonaggorka newmassbasedpopulationbalancemodelincludingshearrateeffectsapplicationtostruviterecovery |