Poly Disc Filter
Disc-based mechanical filtration for removing fibres, pulp residues, and suspended solids from paper mill and industrial process wastewater — automatic backwash and protection of downstream treatment equipment
Overview
About Poly Disc Filter
Poly disc filters are mechanical filtration units designed to remove suspended solids — including fibres, pulp residues, fine particles, and other particulate matter — from industrial process and wastewater streams. The filtration medium consists of multiple closely spaced poly (polymer) discs mounted on a central shaft, which filter suspended solids from the water as it passes between or through the disc surfaces under differential pressure.
In paper mill applications, poly disc filters are particularly effective at capturing cellulosic fibres, filler particles, and coating materials that are present in high concentrations in paper machine whitewater and effluent streams. By removing these solids before the wastewater enters the main treatment system, the poly disc filter significantly reduces the load on downstream clarifiers, biological treatment stages, and membrane systems — extending their operational life and improving their efficiency.
The filter operates continuously with an integrated automatic backwash system that cleans the disc surfaces when the differential pressure across the filter rises to a set threshold. This self-cleaning capability minimises operator intervention and maintains consistent filtration performance over extended operating periods. The system integrates readily into existing treatment infrastructure and accommodates fluctuating influent suspended solids concentrations typical of batch manufacturing processes.
Process
How a Poly Disc Filter Works
Influent Entry
Process wastewater or effluent enters the filter housing and contacts the rotating poly disc assembly. Flow is distributed across the full disc surface area to ensure uniform filtration and prevent localised overloading of any section of the filter medium.
Filtration Through Disc Surfaces
Wastewater passes through the gaps between adjacent poly disc surfaces (or through the disc material itself, depending on the design). Fibres, pulp residues, and suspended solids above the rated filtration size are captured and retained on the disc surfaces, while clarified water passes through to the filtrate collection chamber.
Filtrate Collection
Filtered water collects in the internal chamber and is discharged through the outlet for reuse, further treatment, or discharge. The filter operates continuously while differential pressure across the disc stack remains within operating limits.
Automatic Backwash
When suspended solids accumulation raises the differential pressure to the set threshold, the automatic backwash system activates. Backwash water flows in the reverse direction through the disc surfaces, releasing captured solids from the filter medium. The backwash cycle is brief and does not significantly interrupt the filtration process.
Reject Disposal
Backwash water carrying the dislodged solids is collected in a reject channel and directed to a sludge collection sump or returned to the main wastewater treatment system for further processing. The solid-rich reject may be thickened and dewatered for disposal or fibre recovery.
Benefits
Key Advantages
- Effective removal of fibres, pulp residues, and suspended solids from complex industrial wastewater
- Automatic backwash maintains consistent performance with minimal operator intervention
- Protects downstream clarifiers, biological systems, and membrane units from high solids loading
- Reduces overall TSS load to the treatment system, improving downstream efficiency
- Compact design accommodates integration into existing treatment infrastructure
- Handles fluctuating influent TSS concentrations — flexible for batch manufacturing operations
- Improves water clarity for compliance with discharge standards or internal reuse quality targets
- Reduces fouling and wear on downstream mechanical and membrane equipment
- Simple structure with few moving parts — low maintenance frequency
- Suitable for both new installations and retrofitting into existing wastewater treatment plants
Applications
Industries & Use Cases
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