Polymer Dosing
Bulk handling equipment since 1962
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Polymer dosing is the key to effective dewatering. The correct amount of polymer allows the sludge to form strong flocs, which in turn results in dry sludge, clear filtrate, and stable operation. Too little or too much polymer has an immediate impact on floc formation, filtrate quality, and machine performance. A properly calibrated polymer station ensures precise dosing every time.
Polymer Dosing
Polymer dosing is the process of adding a carefully controlled amount of polymer to sludge to ensure effective separation of water. When the dosing is correct, the sludge forms clear and stable flocs. These flocs enable efficient dewatering and result in a dry, manageable final product.
Why Is Polymer Dosing Important?
- Improved Dewatering:
The right amount of polymer helps the sludge form large, strong flocs that expel as much water as possible. - Stable Operation:
Accurate dosing is essential for optimal performance of the screw press. - Higher Filtrate Quality:
Incorrect dosing leads to cloudy or “milky” filtrate—an indication that polymer adjustment is needed. - Lower Chemical Consumption:
Overdosing is costly and can weaken the flocs. Correct dosing saves both polymer and energy.
How Does Polymer Dosing Work?
The polymer is first mixed with water to activate it, then pumped into a mixing tank together with the sludge.
- Sludge and polymer are blended in a dedicated tank where the polymer is given time to “mature.”
- Polymer maturation time varies depending on temperature and polymer type and must be monitored closely.
- In the screw press, sludge is pushed through a filtrating zone where water drains off, while the flocs are conveyed toward the pressure zone.
Signs of Correct Dosing
- Flocs are large, firm, and stable
- Filtrate is clear, with no visible particles
- The sludge cake is dry and free of loose water
Signs of Incorrect Dosing
Underdosing:
- Small or unstable flocs
- Sludge seeps or leaks through the screen
- Filtrate becomes cloudy or milky
Overdosing:
- Flocs become slimy and break apart
- Increased polymer consumption without improved dewatering
- May cause buildup and unstable operation inside the press
How to Determine the Correct Dose
The correct polymer dose depends on sludge type, dry solids content, and temperature. Therefore, we always recommend:
- Jar Test / Small-Scale Test
A small mixing test provides a reliable estimate of the required polymer amount. - Continuous Visual Inspection
Large flocs and clear filtrate indicate correct dosing. - Adjustments During Operation
Variations in sludge (e.g., changes in DS%) require ongoing adjustments.
Equipment for Accurate Polymer Dosing
- Polymer dosing pump
- Mixing chamber
- Buffer tank with level control
- Dosing pump for the prepared polymer solution
This equipment ensures consistent and continuous polymer dosing—and therefore stable system performance.