BOD, COD and you use a lab sample?

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BOD, COD and you use a lab sample?

• 2nd Water/Wastewater and Automatic Controls
  Conference
• Orlando August 9, 2007

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Presenter

• Robert Lagrange Co author
• Business Manager Tracy Doane-Weideman
• Water and Wastewater Product Manager
• Analysis
• EndressHauser Inc.

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Schedule

• Organic Load
• Importance for plant operation
• Laboratory Measurements
• BOD 5
• COD
• On-Line Measurements
• BOD
• COD
• Questions

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Is it important to know the organic load ?

• A change of organic load requires process
  adjustments
• Controlling the Dissolved Oxygen concentration in
  the aeration tank is a typical way to compensate
  for this
• But !!!!
• It could be too late if the plant capacity is
  limited
• It is better to know ahead of time,
• much more if there is a possibility to equalize
  the load
• or limit the intake of high load from
  industrial plants

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BOD variations at a municipal WWTP
Reference Finbarr O Riordan
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Measurement of Organic Load

• TOC
• COD
• BOD
• the fundamental purpose of the treatment plant
  is to reduce the bio-digestible organics

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Issues with laboratory measurement

• BOD 5 Lab
• Takes 5 days
• Accuracy/Repeatability

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Accuracy of lab measurement
Reference M. Köhne
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Issues with laboratory measurement

• BOD 5 Lab
• Takes 5 days
• Accuracy/Repeatability
• COD
• Takes 2 hours
• Maintenance of the lab instrument
• Disposal of waste stream depending on method

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Michaelis- Menten Kinetic Model
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How does it work?

• Thousands of small plastic rings within the
  bioreactor provide a growth surface for the
  biomass.
• The biomass is fed a mixture of wastewater and
  oxygen saturated dilution water
• The dilution is constantly adjusted to maintain a
  3mg/l oxygen consumption
• The ratio of wastewater to dilution water defines
  BOD based on the Michaelis- Menten Kinetic Model

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Construction
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Trending Calibration
Reference Alexander Borys
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Another trending example
Reference Finbarr O Riordan
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Maintenance On-line BOD
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On-Line COD

• Ozone is mixed with dilution water. The resulting
  concentration is measured by the first ozone
  sensor.
• In the reaction chamber the waste water is
  oxidized by the ozonized dilution water
• The ozone concentration in the reactor is
  measured by the second ozone sensor.
• The consumption of Ozone is proportional to the
  COD

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Use of BOD for monitoring and control
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Use of BOD for balancing load
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Thank you !
Questions ?