Towards improved 1-D settler modelling: calibration of the Bürger model and case study
Author
Summary, in English
Recently, Burger et al. (2011) developed a new 1-D SST model which allows for more realistic
predictions of the sludge settling behaviour than traditional 1-D models used to date. However, the
addition of a compression function in this new 1-D model complicates the model calibration. This
study aims to report advances in the calibration of this novel 1-D model. Data of the evolution of
the sludge blanket height during batch settling experiments were collected at different initial solids
concentrations. Based on the linear slopes of the batch settling curves the hindered settling velocity
functions by Vesilind (1968) and Takacs et al. (1991) were calibrated. Although both settling
velocity functions gave a good fit to the experimental data, very large confidence intervals were
found for the parameters of the settling velocity by Takacs. Global sensitivity analysis showed that
it is not possible to find a unique set of parameter values for the settling function by Takacs based on
experimental data of the hindered settling velocity. Subsequently, the calibrated Vesilind settling
velocity was implemented in the 1-D model by Burger et al. (2011) and the parameters of the
additional compression function were calibrated by fitting the model by Burger et al. (2011) to the
batch settling curves. Simulation results showed that while the 1-D model by Takacs et al. (1991)
underpredicted the experimental data of sludge blanket heights, the model by Burger et al. (2011)
was able to predict the experimental data far more accurately. However, a global sensitivity analysis
showed that no unique optimum for the combined set of hindered and compression parameters
could be found.
predictions of the sludge settling behaviour than traditional 1-D models used to date. However, the
addition of a compression function in this new 1-D model complicates the model calibration. This
study aims to report advances in the calibration of this novel 1-D model. Data of the evolution of
the sludge blanket height during batch settling experiments were collected at different initial solids
concentrations. Based on the linear slopes of the batch settling curves the hindered settling velocity
functions by Vesilind (1968) and Takacs et al. (1991) were calibrated. Although both settling
velocity functions gave a good fit to the experimental data, very large confidence intervals were
found for the parameters of the settling velocity by Takacs. Global sensitivity analysis showed that
it is not possible to find a unique set of parameter values for the settling function by Takacs based on
experimental data of the hindered settling velocity. Subsequently, the calibrated Vesilind settling
velocity was implemented in the 1-D model by Burger et al. (2011) and the parameters of the
additional compression function were calibrated by fitting the model by Burger et al. (2011) to the
batch settling curves. Simulation results showed that while the 1-D model by Takacs et al. (1991)
underpredicted the experimental data of sludge blanket heights, the model by Burger et al. (2011)
was able to predict the experimental data far more accurately. However, a global sensitivity analysis
showed that no unique optimum for the combined set of hindered and compression parameters
could be found.
Department/s
- Mathematics (Faculty of Engineering)
- Partial differential equations
- Numerical Analysis
Publishing year
2013
Language
English
Publication/Series
Proceedings of 86th Annual Water Environment Federation Technical Exhibition and Conference (WEFTEC 2013)
Links
Document type
Conference paper
Topic
- Water Engineering
- Computational Mathematics
- Water Treatment
Keywords
- SST
- calibration
- global sensitivity analysis
- compression settling
- batch settling tests
Conference name
86th Annual Water Environment Federation Technical Exhibition and Conference (WEFTEC 2013)
Conference date
2013-10-05 - 2013-10-09
Conference place
Mc Cormick Place South, Chicago, IL, United States
Status
Published
Research group
- Partial differential equations
- Numerical Analysis