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Compass CPR (Chemical Phosphorus Removal) is an advanced coagulation control system utilising spectroscopy to determine organics, suspended solids and phosphorus in real time. 

In this case study, the power of online spectroscopy is fully utilised. 

By using an online submersible spectrophotometer, total coagulant demand on the inlet to the wastewater treatment plant can be determined. With up to 70% of coagulant demand being made up of the organics and the suspended solids, a control system that doesn’t include these elements can never truly optimise phosphorus removal, nor coagulant dosing.


In this case study, a UK site trialled a Compass CPR system to better understand their influent and test the ability of the system to output a total phosphorus and orthophosphate result without the use of reagents.

Traditional coagulation control systems in wastewater use an online colorimeter to measure orthophosphate and dose accordingly to this mg/l in conjunction with the flow. This has several disadvantages which Compass CPR overcomes.


By utilising a Compass CPR system, a wastewater site can:


  • Measure total coagulant demand in real time and dose coagulant  only when it is needed regardless of the source (organics, TSS or phosphorus)
  • Determine online phosphorus measurement using a direct insertion sensor and without reagents. No more difficulty with filtration or ensuring there are reagents present in the analyser.
  • Overall reduction in coagulant dosing, reducing OpEx and the risk of metal discharge compliance issues.
Knowledgeable, experienced staff.

Need some advice or support? We’re here to help.

If you need a call back about how Process Measurement and Analysis can help you or have any questions at all please feel free to contact us at [email protected].  A member of our experienced team will contact you directly.

Fowzie Smith-Tahir

Marketing and IT Director

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Process Measurement and Analysis Ltd, Brook Mills House, Carr Lane, Slaithwaite, Huddersfield, HD7 5BG United Kingdom