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Effects of ionic strength and ion pairing on (plant-wide) modelling of anaerobic digestion.

Solon, Kimberly LU ; Flores-Alsina, Xavier; Mbamba, Christian Kazadi; Volcke, Eveline I P; Tait, Stephan; Batstone, Damien; Gernaey, Krist LU and Jeppsson, Ulf LU (2015) In Water Research 70(March). p.235-245
Abstract
Plant-wide models of wastewater treatment (such as the Benchmark Simulation Model No. 2 or BSM2) are gaining popularity for use in holistic virtual studies of treatment plant control and operations. The objective of this study is to show the influence of ionic strength (as activity corrections) and ion pairing on modelling of anaerobic digestion processes in such plant-wide models of wastewater treatment. Using the BSM2 as a case study with a number of model variants and cationic load scenarios, this paper presents the effects of an improved physico-chemical description on model predictions and overall plant performance indicators, namely effluent quality index (EQI) and operational cost index (OCI). The acid-base equilibria implemented in... (More)
Plant-wide models of wastewater treatment (such as the Benchmark Simulation Model No. 2 or BSM2) are gaining popularity for use in holistic virtual studies of treatment plant control and operations. The objective of this study is to show the influence of ionic strength (as activity corrections) and ion pairing on modelling of anaerobic digestion processes in such plant-wide models of wastewater treatment. Using the BSM2 as a case study with a number of model variants and cationic load scenarios, this paper presents the effects of an improved physico-chemical description on model predictions and overall plant performance indicators, namely effluent quality index (EQI) and operational cost index (OCI). The acid-base equilibria implemented in the Anaerobic Digestion Model No. 1 (ADM1) are modified to account for non-ideal aqueous-phase chemistry. The model corrects for ionic strength via the Davies approach to consider chemical activities instead of molar concentrations. A speciation sub-routine based on a multi-dimensional Newton-Raphson (NR) iteration method is developed to address algebraic interdependencies. The model also includes ion pairs that play an important role in wastewater treatment. The paper describes: 1) how the anaerobic digester performance is affected by physico-chemical corrections; 2) the effect on pH and the anaerobic digestion products (CO2, CH4 and H2); and, 3) how these variations are propagated from the sludge treatment to the water line. Results at high ionic strength demonstrate that corrections to account for non-ideal conditions lead to significant differences in predicted process performance (up to 18% for effluent quality and 7% for operational cost) but that for pH prediction, activity corrections are more important than ion pairing effects. Both are likely to be required when precipitation is to be modelled. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Physico-chemical framework, Wastewater plant-wide modelling
in
Water Research
volume
70
issue
March
pages
235 - 245
publisher
Elsevier
external identifiers
  • pmid:25540837
  • wos:000350513400022
  • scopus:84919742984
ISSN
1879-2448
DOI
10.1016/j.watres.2014.11.035
language
English
LU publication?
yes
id
b75f4a5d-59a1-4612-8c56-424350ca72eb (old id 4905635)
date added to LUP
2015-03-11 10:37:54
date last changed
2017-10-22 03:22:53
@article{b75f4a5d-59a1-4612-8c56-424350ca72eb,
  abstract     = {Plant-wide models of wastewater treatment (such as the Benchmark Simulation Model No. 2 or BSM2) are gaining popularity for use in holistic virtual studies of treatment plant control and operations. The objective of this study is to show the influence of ionic strength (as activity corrections) and ion pairing on modelling of anaerobic digestion processes in such plant-wide models of wastewater treatment. Using the BSM2 as a case study with a number of model variants and cationic load scenarios, this paper presents the effects of an improved physico-chemical description on model predictions and overall plant performance indicators, namely effluent quality index (EQI) and operational cost index (OCI). The acid-base equilibria implemented in the Anaerobic Digestion Model No. 1 (ADM1) are modified to account for non-ideal aqueous-phase chemistry. The model corrects for ionic strength via the Davies approach to consider chemical activities instead of molar concentrations. A speciation sub-routine based on a multi-dimensional Newton-Raphson (NR) iteration method is developed to address algebraic interdependencies. The model also includes ion pairs that play an important role in wastewater treatment. The paper describes: 1) how the anaerobic digester performance is affected by physico-chemical corrections; 2) the effect on pH and the anaerobic digestion products (CO2, CH4 and H2); and, 3) how these variations are propagated from the sludge treatment to the water line. Results at high ionic strength demonstrate that corrections to account for non-ideal conditions lead to significant differences in predicted process performance (up to 18% for effluent quality and 7% for operational cost) but that for pH prediction, activity corrections are more important than ion pairing effects. Both are likely to be required when precipitation is to be modelled.},
  author       = {Solon, Kimberly and Flores-Alsina, Xavier and Mbamba, Christian Kazadi and Volcke, Eveline I P and Tait, Stephan and Batstone, Damien and Gernaey, Krist and Jeppsson, Ulf},
  issn         = {1879-2448},
  keyword      = {Physico-chemical framework,Wastewater plant-wide modelling},
  language     = {eng},
  number       = {March},
  pages        = {235--245},
  publisher    = {Elsevier},
  series       = {Water Research},
  title        = {Effects of ionic strength and ion pairing on (plant-wide) modelling of anaerobic digestion.},
  url          = {http://dx.doi.org/10.1016/j.watres.2014.11.035},
  volume       = {70},
  year         = {2015},
}