Measure
Online instruments characterise incoming water quality.
Start at the source.
Predictive coagulation control for drinking-water turbidity and organics removal.
One source. Two control approaches.
Compass predicts the coagulant dose from incoming water quality. Compass EOR adds treated-water feedback to trim the prediction for the enhanced organics-removal duty.
The intelligence behind Compass
Water data. A clearer decision.
Compass brings online measurements and a site-specific algorithm together to calculate coagulant demand.
Incoming water qualityCalculated dose
Changing conditions over timeIllustrative relationship · not site performance data
Predict
A site-specific algorithm translates the measurements into coagulant demand.
Control
A calculated dose output supports the agreed plant control arrangement.
Every source has a story.
Follow the incoming water as conditions change, then see what the model is responding to.
Compass data / illustrative interface
See the signal. See the decision.
Read incoming turbidity and dissolved organic carbon (DOC) alongside the calculated dose. In this example, the dose responds to rising organics even while turbidity falls.
Incoming turbidity06.8NTU · demo value
Incoming DOC05.2mg/L · demo DOCeq
Calculated dose38.4mg/L · demo value
Incoming turbidityIncoming DOCCalculated dose
EarlierTime →Now
Illustrative UI only. Fictional values; trends use separate relative scales. DOC is shown as an optical equivalent (DOCeq). Site-specific calibration and validation are required.
Understanding the dose
Two signals.
One informed dose.
Turbidity is only part of the picture. Dissolved organics can change on a different timescale. Read both signals to understand what the dose is responding to.
Read the incoming change.
An increase in particulate material changes the turbidity signal. The organic signal adds another part of the water-quality picture.
Particulate signal
Incoming turbidity
Rising
Organic signal
Incoming DOC
Changing more slowly
Site-specific model
Calculated
coagulant dose.
The site-specific model uses the incoming measurements to calculate a coagulant-dose demand.
Illustrative sequence, not live plant data. The timing, measurements, model and dose limits depend on the individual works.
Compass EOR / enhanced organics removal
Add feedback.
Close the loop.
Compass EOR adds a treated-water optical measurement. This feedback trims the incoming-water prediction against the agreed organics-removal objective.
- 01
Predict
Calculate demand from incoming water quality.
- 02
Treat
Apply the agreed coagulation and treatment process.
- 03
Measure
Read the optical signal after treatment.
Treated-water feedback trims the prediction.
Standard Compass uses incoming-water prediction for the turbidity duty. EOR adds feedback for the enhanced organics-removal duty.
Why organics matter.
Natural organic matter can react with chemical disinfectants to form disinfection by-products. Removing coagulable organic matter before disinfection can help manage precursor loading, while effective disinfection remains essential.
Compass EOR connects an organics-removal objective with a dose prediction and treated-water feedback. The achievable result is assessed and validated for the individual works.
Sources behind this explanation
The later DOC peak is illustrated in Lutra’s historic Wainuiomata example. The sequence above explains the principle without reproducing that site’s measurements or results.
Lutra: Wainuiomata case studyPMA: Compass and Compass EORDWI: disinfection by-products and precursorsThe storm passes.
The water keeps changing.
Follow a river through a change in weather. See how turbidity and dissolved organic carbon can tell different parts of the story.
Incoming turbidityNTU · illustrative
Incoming DOCmg/L · illustrative DOCeq
TurbidityDOCRelative trends · separate scales
Drag the round handle to explore. Or use the arrow keys to move between weather stages.
Illustrative sequence, not live readings or a weather forecast. Values are fictional; timing varies by catchment. DOC is shown as an optical equivalent (DOCeq).
Clear skies aren’t
the whole picture.
In this example, turbidity falls as the storm eases, while DOC continues to rise. Reading both signals helps explain why the water still needs attention.
The final step represents a later recovery, not an immediate return to normal when the sun appears.
About this example
Based on Roger’s meeting explanation. This interactive example is part of the PMA Compass website, with fictional values and a fixed-camera weather sequence. Weather is context for the story: it is not used here to calculate a dose or predict a plant reading.
Research documents event-specific differences in the timing of turbidity and organic signals. It does not imply that every river behaves this way.
Research: storm-event optical measurements ↗Lutra: Wainuiomata example ↗
Make each measurement matter.
Characterise the incoming water.
Calculate a site-specific dose.
Add feedback for EOR.
A clearer starting point
Your questions,
answered.
How is feed-forward control different?
Feed-forward control uses measurements of incoming water quality to calculate a dose before changes pass through treatment. A site-specific algorithm relates those measurements to coagulant demand.
Which Compass model should we consider?
Compass and Compass EOR cover drinking-water duties. Compass CPR and Compass CEP cover distinct wastewater duties. PMA can review your treatment objective, existing process and available measurements.
Does every installation use the same instruments?
The instrumentation and integration depend on the system generation and the site. A configuration review establishes the sensors, control signals, communications and installation arrangement for your project.
Can we use our existing plant measurements?
Share the instruments, signals and control arrangement already available at your site. Compatibility and the measurements required for your application need to be reviewed for the proposed configuration.
