What Is a Lamella Clarifier?
A lamella clarifier is a compact gravity settling device used to separate suspended solids from water or wastewater. It is also commonly called an inclined plate clarifier, lamella plate clarifier, inclined plate settler, or slant plate clarifier.
The purpose is simple: remove solids from liquid before the water is dis
Water Treatment Solutions
How a Lamella Clarifier Works
A lamella clarifier removes suspended solids from wastewater by using gravity and inclined plate settling. Wastewater flows upward through a series of angled plates, allowing solids to settle onto the plate surfaces while clarified water exits from the top.
As the water moves through the plate pack, solids only need to travel a short vertical distance before contacting a surface. This increases settling efficiency and allows the system to operate in a much smaller footprint compared to a conventional clarifier.
Settled solids slide down the inclined plates into the sludge cone at the bottom of the unit, where they are collected and removed for further processing, typically using a filter press.
Key Process Steps
- Wastewater enters the clarifier after chemical treatment
- Flow is evenly distributed below the plate pack
- Water rises upward through inclined plates
- Solids settle onto plates and slide downward
- Sludge collects in the cone bottom
- Clarified water exits the top
Lamella Clarifier Design Formula
A lamella clarifier is typically sized using surface overflow rate (SOR), which is based on the effective settling area created by the inclined plates.
Effective settling area can be estimated using:
Effective Area = Number of Plates × Plate Length × Plate Width × cos(Plate Angle)
This allows a lamella clarifier to provide significantly more settling area than a conventional clarifier with the same footprint.
Lamella Clarifier Maintenance and Cleaning
Proper maintenance of a lamella clarifier is critical to ensure consistent performance, prevent solids carryover, and extend the life of the equipment.
One of the most important maintenance tasks is regular sludge removal. As solids settle onto the inclined plates, they slide down into the sludge cone at the bottom of the clarifier. If this sludge is not removed frequently, it can compact and harden, reducing the available volume inside the clarifier. This can lead to a condition commonly referred to as “rat-holing,” where only a small channel remains open for flow, allowing solids to pass through to the effluent.
Most industrial lamella clarifier systems use an automatic sludge blowdown system to prevent this issue. A typical setup may run for a short duration every few minutes to keep solids moving and maintain a healthy sludge blanket without overfilling the cone.
Lamella Clarifier vs Dissolved Air Flotation (DAF)
Lamella clarifiers are typically the better choice for:
- Metal finishing wastewater
- Mining and aggregate wastewater
- Applications with dense, settleable solids
- Systems where lower operating cost is important
DAF systems are often preferred for:
- Wastewater containing oils and grease
- Food processing wastewater
- Light or non-settleable solids
- Applications requiring flotation rather than settling
From an operational standpoint, lamella clarifiers generally have lower energy consumption and fewer moving parts, making them simpler and more cost-effective to operate over time. DAF systems require air compressors, recycle pumps, and more complex controls, which can increase both capital and operating costs.
In many industrial wastewater systems, a lamella clarifier is the preferred solution when solids can be chemically treated to settle, especially when combined with downstream sludge dewatering equipment such as a filter press.
Need help sizing a lamella clarifier?
Contact Met-Chem to review your flow rate, wastewater chemistry, solids loading, and system layout.
Call (216) 881-7900 or email dsenney@metchem.com.