Advanced

Fundamental nonlinearities of the reactor-settler interaction in the activated sludge process

Diehl, Stefan LU and Farås, Sebastian LU (2012) In Water Science and Technology 66(1). p.28-35
Abstract
The activated sludge process can be modelled by ordinary and partial differential equations for the biological reactors and secondary settlers, respectively. Because of the complexity of such a system, simulation models are most often used to investigate them. However, simulation models cannot give general rules on how to control a complex nonlinear process. For a reduced-order model with only two components, soluble substrate and particulate biomass, general results on steady-state solutions have recently been obtained, such as existence, uniqueness and stability of solutions. The aim of the present paper is to utilize those results to formulate some implications of practical importance. In particular, strategies are described for the... (More)
The activated sludge process can be modelled by ordinary and partial differential equations for the biological reactors and secondary settlers, respectively. Because of the complexity of such a system, simulation models are most often used to investigate them. However, simulation models cannot give general rules on how to control a complex nonlinear process. For a reduced-order model with only two components, soluble substrate and particulate biomass, general results on steady-state solutions have recently been obtained, such as existence, uniqueness and stability of solutions. The aim of the present paper is to utilize those results to formulate some implications of practical importance. In particular, strategies are described for the manual control of the effluent substrate concentration subject to the constraint that the settler is maintained in normal operation (with a sludge blanket in the thickening zone) in steady state. Such strategies contain how the two control parameters, the recycle and waste volumetric flow ratios, should be chosen for any (steady-state) values of the input variables. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Clarifier, Continuous sedimentation, Modelling, Partial differential equation, Thickener
in
Water Science and Technology
volume
66
issue
1
pages
28 - 35
publisher
IWA Publishing
external identifiers
  • wos:000305296700005
  • pmid:22678197
  • scopus:84862627070
ISSN
0273-1223
DOI
10.2166/wst.2012.162
language
English
LU publication?
yes
id
d0a2a102-3eb2-41c5-b546-84cc7f2f29b5 (old id 2859665)
date added to LUP
2012-07-10 14:07:13
date last changed
2017-02-09 11:59:43
@article{d0a2a102-3eb2-41c5-b546-84cc7f2f29b5,
  abstract     = {The activated sludge process can be modelled by ordinary and partial differential equations for the biological reactors and secondary settlers, respectively. Because of the complexity of such a system, simulation models are most often used to investigate them. However, simulation models cannot give general rules on how to control a complex nonlinear process. For a reduced-order model with only two components, soluble substrate and particulate biomass, general results on steady-state solutions have recently been obtained, such as existence, uniqueness and stability of solutions. The aim of the present paper is to utilize those results to formulate some implications of practical importance. In particular, strategies are described for the manual control of the effluent substrate concentration subject to the constraint that the settler is maintained in normal operation (with a sludge blanket in the thickening zone) in steady state. Such strategies contain how the two control parameters, the recycle and waste volumetric flow ratios, should be chosen for any (steady-state) values of the input variables.},
  author       = {Diehl, Stefan and Farås, Sebastian},
  issn         = {0273-1223},
  keyword      = {Clarifier,Continuous sedimentation,Modelling,Partial differential equation,Thickener},
  language     = {eng},
  number       = {1},
  pages        = {28--35},
  publisher    = {IWA Publishing},
  series       = {Water Science and Technology},
  title        = {Fundamental nonlinearities of the reactor-settler interaction in the activated sludge process},
  url          = {http://dx.doi.org/10.2166/wst.2012.162},
  volume       = {66},
  year         = {2012},
}