A Stochastic Method to Manage Delay and Missing Values for In-Situ Sensors in an Alternating Activated Sludge Process

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

Abstract

In the alternating activated sludge process with rule-based control, online N-measurements are of great importance for maintaining good control. These measurements can be delayed due to sensor processing time, turbulence at the location in the aeration tank where the sensor is placed, etc. The measurements may also be temporarily unavailable because of recalibration, communication faults or other errors. Here we present a method that handles such delay and missing observations. The model is based on zero order hold stochastic differential equations which use binary signals for influent flow and aeration to determine the state of the alternating process. It also uses measured ammonium and nitrate concentrations, which are shifted to account for delay. The method is developed and tested with data from a WWTP located in Kolding, Denmark. Results indicate that even though the model is simple, the model residuals and parameters are uncorrelated and the model predictions are 60% closer to the true values (measurements shifted to account for delay) than the delayed measurements are.
Original languageEnglish
Title of host publicationProceedings of the 12th IWA Specialized Conference on Instrumentation, Control & Automation
Number of pages10
Publication date2017
Publication statusPublished - 2017
Event12th IWA Specialized Conference on Instrumentation, Control & Automation - Québec, Canada
Duration: 11 Jun 201714 Jun 2017
Conference number: 12
http://www.ica2017.org/

Conference

Conference12th IWA Specialized Conference on Instrumentation, Control & Automation
Number12
CountryCanada
CityQuébec
Period11/06/201714/06/2017
Internet address

Keywords

  • Grey box
  • WWTP
  • Stochastic
  • Sensor delay
  • Alternating
  • ASP
  • Online control
  • In-situ sensor
  • Rule-based control

Cite this

Stentoft, P. A., Munk-Nielsen, T., Mikkelsen, P. S., & Madsen, H. (2017). A Stochastic Method to Manage Delay and Missing Values for In-Situ Sensors in an Alternating Activated Sludge Process. In Proceedings of the 12th IWA Specialized Conference on Instrumentation, Control & Automation
Stentoft, Peter Alexander ; Munk-Nielsen, Thomas ; Mikkelsen, Peter Steen ; Madsen, Henrik. / A Stochastic Method to Manage Delay and Missing Values for In-Situ Sensors in an Alternating Activated Sludge Process. Proceedings of the 12th IWA Specialized Conference on Instrumentation, Control & Automation. 2017.
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title = "A Stochastic Method to Manage Delay and Missing Values for In-Situ Sensors in an Alternating Activated Sludge Process",
abstract = "In the alternating activated sludge process with rule-based control, online N-measurements are of great importance for maintaining good control. These measurements can be delayed due to sensor processing time, turbulence at the location in the aeration tank where the sensor is placed, etc. The measurements may also be temporarily unavailable because of recalibration, communication faults or other errors. Here we present a method that handles such delay and missing observations. The model is based on zero order hold stochastic differential equations which use binary signals for influent flow and aeration to determine the state of the alternating process. It also uses measured ammonium and nitrate concentrations, which are shifted to account for delay. The method is developed and tested with data from a WWTP located in Kolding, Denmark. Results indicate that even though the model is simple, the model residuals and parameters are uncorrelated and the model predictions are 60{\%} closer to the true values (measurements shifted to account for delay) than the delayed measurements are.",
keywords = "Grey box, WWTP, Stochastic, Sensor delay, Alternating, ASP, Online control, In-situ sensor, Rule-based control",
author = "Stentoft, {Peter Alexander} and Thomas Munk-Nielsen and Mikkelsen, {Peter Steen} and Henrik Madsen",
year = "2017",
language = "English",
booktitle = "Proceedings of the 12th IWA Specialized Conference on Instrumentation, Control & Automation",

}

Stentoft, PA, Munk-Nielsen, T, Mikkelsen, PS & Madsen, H 2017, A Stochastic Method to Manage Delay and Missing Values for In-Situ Sensors in an Alternating Activated Sludge Process. in Proceedings of the 12th IWA Specialized Conference on Instrumentation, Control & Automation. 12th IWA Specialized Conference on Instrumentation, Control & Automation, Québec, Canada, 11/06/2017.

A Stochastic Method to Manage Delay and Missing Values for In-Situ Sensors in an Alternating Activated Sludge Process. / Stentoft, Peter Alexander; Munk-Nielsen, Thomas; Mikkelsen, Peter Steen; Madsen, Henrik.

Proceedings of the 12th IWA Specialized Conference on Instrumentation, Control & Automation. 2017.

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

TY - GEN

T1 - A Stochastic Method to Manage Delay and Missing Values for In-Situ Sensors in an Alternating Activated Sludge Process

AU - Stentoft, Peter Alexander

AU - Munk-Nielsen, Thomas

AU - Mikkelsen, Peter Steen

AU - Madsen, Henrik

PY - 2017

Y1 - 2017

N2 - In the alternating activated sludge process with rule-based control, online N-measurements are of great importance for maintaining good control. These measurements can be delayed due to sensor processing time, turbulence at the location in the aeration tank where the sensor is placed, etc. The measurements may also be temporarily unavailable because of recalibration, communication faults or other errors. Here we present a method that handles such delay and missing observations. The model is based on zero order hold stochastic differential equations which use binary signals for influent flow and aeration to determine the state of the alternating process. It also uses measured ammonium and nitrate concentrations, which are shifted to account for delay. The method is developed and tested with data from a WWTP located in Kolding, Denmark. Results indicate that even though the model is simple, the model residuals and parameters are uncorrelated and the model predictions are 60% closer to the true values (measurements shifted to account for delay) than the delayed measurements are.

AB - In the alternating activated sludge process with rule-based control, online N-measurements are of great importance for maintaining good control. These measurements can be delayed due to sensor processing time, turbulence at the location in the aeration tank where the sensor is placed, etc. The measurements may also be temporarily unavailable because of recalibration, communication faults or other errors. Here we present a method that handles such delay and missing observations. The model is based on zero order hold stochastic differential equations which use binary signals for influent flow and aeration to determine the state of the alternating process. It also uses measured ammonium and nitrate concentrations, which are shifted to account for delay. The method is developed and tested with data from a WWTP located in Kolding, Denmark. Results indicate that even though the model is simple, the model residuals and parameters are uncorrelated and the model predictions are 60% closer to the true values (measurements shifted to account for delay) than the delayed measurements are.

KW - Grey box

KW - WWTP

KW - Stochastic

KW - Sensor delay

KW - Alternating

KW - ASP

KW - Online control

KW - In-situ sensor

KW - Rule-based control

M3 - Article in proceedings

BT - Proceedings of the 12th IWA Specialized Conference on Instrumentation, Control & Automation

ER -

Stentoft PA, Munk-Nielsen T, Mikkelsen PS, Madsen H. A Stochastic Method to Manage Delay and Missing Values for In-Situ Sensors in an Alternating Activated Sludge Process. In Proceedings of the 12th IWA Specialized Conference on Instrumentation, Control & Automation. 2017