Rainfall, changing abstraction and seasonal source-water variation can alter the water arriving at a UK treatment works. A dose that suited the previous operating period may need review, but a new control strategy must fit the whole treatment process.
Compass automatic coagulation control uses continuous incoming-water measurements and a site-specific model to calculate coagulant-dose demand. Its feed-forward approach is intended to respond to the water entering the works, with the output integrated into the agreed plant control philosophy.
Start with the works and its operating objective
Define what the project is intended to improve. That might be a more consistent response to changing source water, filtered-water turbidity performance or an agreed organics-removal objective. Establish a baseline using the works’ own measurements and operating records.
The model, instruments and limits must reflect the source water and coagulant. A successful arrangement at another works does not establish the right dose relationship for this one. Keep source-water conditions, pH and alkalinity considerations, treatment constraints and existing dosing equipment in the review.
Agree what happens when a signal is lost
A control proposal should describe normal operation and the response to an unavailable measurement. Give operators a clear route to recognise the condition and follow the agreed fallback procedure.
Separate prediction from feedback
Standard Compass uses source-water measurements for feed-forward prediction. Compass EOR adds treated-water optical feedback to trim the prediction against a defined enhanced organics-removal objective. These configurations should be selected around the process question rather than treated as identical control arrangements.
Downstream measurements remain useful context. The filter-effluent turbidity record, for example, helps the team review filtration performance. Account for sample and treatment delays before linking an incoming-water event to a downstream change.
Make the control handover reviewable
Write down the permitted operating modes, dose limits, signal validity checks and responsibility for changing settings. Confirm how the demand reaches the dosing system and how operators can see the active mode. Any fallback or manual operation needs to follow the works’ approved procedure.
Plan commissioning around agreed evidence: source-water conditions, dose demand, delivered dose where available, downstream results and operator observations. Include normal periods and relevant changes. Review the existing Mythe WTW case study as historical context, while keeping acceptance criteria specific to your installation.
Build the application brief
Provide PMA with the source-water profile, coagulant and dose range, treatment objective, current instruments, sample arrangements and control-system requirements. Include the people who will commission, operate and maintain the system.
Expected performance and chemical use must be assessed against current site data. An automatic controller supports a defined operating strategy; it does not remove the need for verification, instrument care and accountable decisions by the operating team.
Technical references
Advanced Automatic Coagulation Control in Water Treatment
