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A hedging point strategy - balancing effluent quality, economy and robustness in the control of wastewater treatment plants

Ingildsen, P; Olsson, Gustaf LU and Yuan, Z (2002) In Water Science and Technology 45(4-5). p.317-324
Abstract
An operational space map is an efficient tool to compare a large number of operational strategies to find an optimal choice of setpoints based on a multicriterion. Typically, such a multicriterion includes a weighted sum of cost of operation and effluent quality. Due to the relative high cost of aeration such a definition of optimality result in a relatively high fraction of the effluent total nitrogen in the form of ammonium. Such a strategy may however introduce a risk into operation because a low degree of ammonium removal leads to a low amount of nitrifiers. This in turn leads to a reduced ability to reject event disturbances, such as large variations in the ammonium load, drop in temperature, the presence of toxic/inhibitory compounds... (More)
An operational space map is an efficient tool to compare a large number of operational strategies to find an optimal choice of setpoints based on a multicriterion. Typically, such a multicriterion includes a weighted sum of cost of operation and effluent quality. Due to the relative high cost of aeration such a definition of optimality result in a relatively high fraction of the effluent total nitrogen in the form of ammonium. Such a strategy may however introduce a risk into operation because a low degree of ammonium removal leads to a low amount of nitrifiers. This in turn leads to a reduced ability to reject event disturbances, such as large variations in the ammonium load, drop in temperature, the presence of toxic/inhibitory compounds in the influent etc. Hedging is a risk minimisation tool, with the aim to "reduce one's risk of loss on a bet or speculation by compensating transactions on the other side" (The Concise Oxford Dictionary (1995)). In wastewater treatment plant operation hedging can be applied by choosing a higher level of ammonium removal to increase the amount of nitrifiers. This is a sensible way to introduce disturbance rejection ability into the multi criterion. In practice, this is done by deciding upon an internal effluent ammonium criterion. In some countries such as Germany, a separate criterion already applies to the level of ammonium in the effluent. However, in most countries the effluent criterion applies to total nitrogen only. In these cases, an internal effluent ammonium criterion should be selected in order to secure proper disturbance rejection ability. (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
removal, operating space diagram, nitrogen, hedging, disturbance rejection, activated sludge, control
in
Water Science and Technology
volume
45
issue
4-5
pages
317 - 324
publisher
IWA Publishing
external identifiers
  • wos:000174872000039
  • pmid:11936649
  • scopus:0036209697
ISSN
0273-1223
language
English
LU publication?
yes
id
f0e91d25-ddac-4e29-b861-53b8d03143ce (old id 340486)
alternative location
http://www.iwaponline.com/wst/04504/0317/045040317.pdf
date added to LUP
2007-10-22 15:45:51
date last changed
2017-10-29 04:26:03
@article{f0e91d25-ddac-4e29-b861-53b8d03143ce,
  abstract     = {An operational space map is an efficient tool to compare a large number of operational strategies to find an optimal choice of setpoints based on a multicriterion. Typically, such a multicriterion includes a weighted sum of cost of operation and effluent quality. Due to the relative high cost of aeration such a definition of optimality result in a relatively high fraction of the effluent total nitrogen in the form of ammonium. Such a strategy may however introduce a risk into operation because a low degree of ammonium removal leads to a low amount of nitrifiers. This in turn leads to a reduced ability to reject event disturbances, such as large variations in the ammonium load, drop in temperature, the presence of toxic/inhibitory compounds in the influent etc. Hedging is a risk minimisation tool, with the aim to "reduce one's risk of loss on a bet or speculation by compensating transactions on the other side" (The Concise Oxford Dictionary (1995)). In wastewater treatment plant operation hedging can be applied by choosing a higher level of ammonium removal to increase the amount of nitrifiers. This is a sensible way to introduce disturbance rejection ability into the multi criterion. In practice, this is done by deciding upon an internal effluent ammonium criterion. In some countries such as Germany, a separate criterion already applies to the level of ammonium in the effluent. However, in most countries the effluent criterion applies to total nitrogen only. In these cases, an internal effluent ammonium criterion should be selected in order to secure proper disturbance rejection ability.},
  author       = {Ingildsen, P and Olsson, Gustaf and Yuan, Z},
  issn         = {0273-1223},
  keyword      = {removal,operating space diagram,nitrogen,hedging,disturbance rejection,activated sludge,control},
  language     = {eng},
  number       = {4-5},
  pages        = {317--324},
  publisher    = {IWA Publishing},
  series       = {Water Science and Technology},
  title        = {A hedging point strategy - balancing effluent quality, economy and robustness in the control of wastewater treatment plants},
  volume       = {45},
  year         = {2002},
}