Function:
pH correction of clarified water
pH neutralisation plant
The pH neutralisation plant is used as a tertiary treatment stage when clarified water has an excessively high pH. By dosing acidic solutions or CO₂, the system lowers the pH and restores the water to neutral conditions, making it suitable for discharge to sewer systems or surface waters, subject to applicable discharge requirements.
How pH neutralisation works
Chemical dosing to restore the water to neutral conditions.
Reagent dosing
The clarified water leaving the clarifier is transferred to a dedicated tank, where neutralisation takes place by dosing either an acidic solution or carbon dioxide (CO₂).
pH reduction
When CO₂ is used, it is injected in gaseous form and dissolves in the water, forming carbonic acid. This chemical reaction lowers the water pH towards neutral conditions.
CO₂-based neutralisation
Compared with acid-based neutralisation, CO₂ dosing avoids the handling of corrosive acids and does not directly increase the salt concentration of the treated water.
Technology and construction
Components for continuous pH measurement and controlled reagent injection.
Venturi-tube injection
The plant uses a Venturi tube to promote CO₂ dissolution and uniform mixing in the treated water.
Sensors
The pH of the treated water is measured continuously by an immersion pH probe.
Digital pH meter
A digital pH meter with two thresholds and automatic temperature compensation.
Electrical panels and protection
The electrical system comprises a dedicated dosing unit and control panel, both rated IP55.
Standard and optional equipment
Standard equipment
- Venturi injection system for CO₂ dissolution and mixing in the treated water.
- Immersion pH probe complete with transmitter and cleaning system.
- Digital pH meter with two thresholds and temperature compensation.
- Dedicated dosing unit and control panel, both rated IP55.
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