Parkson Lamella Clarifier Manual – Operation & Maintenance

Parkson manufactured Lamella Gravity Settlers in numerous sizes and configurations.

The original Parkson brochure supplied with this resource identifies packaged LGS models including:

75/55, 125/55, 200/55, 300/55, 570/55, 860/55, 1135/55, 1500/55, 2000/55, 2500/55, and 3900/55.

Larger packaged LGST Gravity Settler/Thickener models shown include:

150/55, 360/55, 620/55, 1120/55, 1800/55, 2480/55, 3250/55, and 3915/55.

If your equipment tag contains one of these Parkson model numbers, Met-Chem may be able to assist with replacement Lamella plate packs, components, troubleshooting, or complete clarifier replacement.

Many Parkson Lamella Gravity Settlers have been operating for decades. Original manuals can therefore be extremely useful when troubleshooting or rebuilding an older unit.

The original Parkson documentation we have reviewed includes information covering:

• Installation and leveling
• Pre-startup inspection
• Lamella settling theory and design
• Flow distribution
• Overflow weir adjustment
• Chemical treatment
• Polymer preparation and dosage
• Flocculation
• Feed pump operation
• Sludge underflow
• Sludge recycle
• Startup and shutdown
• Troubleshooting
• Settling tests
• Rectangular overflow weir tables

The original manual specifically states that its instructions cover installation, operation, and maintenance of Parkson equipment and components.

If you have an older Parkson clarifier and need assistance identifying the model, send Met-Chem a photograph of the clarifier and equipment nameplate. We can help determine what replacement components may be available.

 The operating principle behind the older Parkson Lamella Gravity Settler is relatively straightforward.

Wastewater enters the clarifier and is distributed across multiple inclined settling plates. Suspended solids settle onto the plate surfaces while clarified water travels upward and exits through the effluent collection system.

The settled material slides down the inclined plates and falls into the sludge collection hopper below.

The original Parkson technical literature describes the Lamella Gravity Settler as an inclined, shallow-depth sedimentation device performing the same basic separation function as a conventional settling basin while occupying substantially less space.

 The important measurement in a Lamella clarifier is not simply the footprint of the tank.

Each inclined plate provides additional projected settling area. By installing many plates inside a relatively small tank, a Lamella clarifier can provide a large effective settling area within a compact footprint.

Parkson's original literature explains this concept using shallow-depth sedimentation and projected settling area. The literature shows the plates inclined at approximately 60 degrees above horizontal, allowing solids deposited on the plates to slide downward.

The older Parkson brochure supplied with this page lists 2-inch plate spacing as part of the design criteria.

 Before placing an older Lamella clarifier into service, several basic items should be checked.

Parkson's original pre-startup instructions emphasize:

1. Protect plastic Lamella plates from prolonged direct sunlight when the unit is not filled with liquid.
2. Verify that the tank is level in both directions.
3. Verify that the adjustable overflow weir is level.
4. Check the flash mixer and flocculator, when supplied.
5. Confirm the feed chemistry using settling tests.
6. Verify the feed pH.
7. Confirm that the feed pump cannot exceed the clarifier's design flow.
8. Establish an appropriate sludge underflow rate.
9. Check the unit for leaks.
10. Run water through the system for a final operational check.

The original instructions specifically warn that the feed pump should not be operated above the process design flow rate.

This is still an important troubleshooting consideration today. Increasing flow through an existing clarifier beyond its original hydraulic design does not necessarily increase treatment capacity. Excessive flow can reduce clarification performance and cause solids carryover.

 Proper flow distribution is one of the most important aspects of operating an older Parkson Lamella Clarifier.

The influent must be distributed evenly through the plate area. Uneven distribution can cause one portion of the clarifier to become hydraulically overloaded while other sections are underutilized.

The original Parkson installation instructions make this point very clearly: the Lamella tank must be level in both directions, because equal flow distribution will not be obtained if the unit is not level. The adjustable overflow weir must also be level to achieve uniform flow distribution.

If you are experiencing poor performance from an older Parkson unit, checking that the clarifier and effluent weirs are level should be one of the first troubleshooting steps.

 A Lamella clarifier separates settleable solids. It does not automatically make dissolved contaminants or extremely fine particles settle.

For many industrial wastewater applications, chemical treatment occurs before clarification.

A typical treatment sequence may include:

pH Adjustment → Coagulation → Flocculation → Lamella Clarification → Sludge Dewatering

The original Parkson manual discusses feed-stream pH, coagulation, polymer preparation, polymer dilution, chemical dosage, and flocculation as important operating variables.

Parkson's troubleshooting instructions also tell operators experiencing high suspended solids in the effluent to check whether enough treatment chemicals are being added and whether the pH is within the proper operating range.

Proper flocculator speed is also important.

If mixing is too aggressive, formed floc can be broken apart. If mixing is inadequate, sufficient floc may never develop.

The objective is to produce a large, durable floc capable of settling efficiently through the Lamella plate section.

 Sludge removal is one of the most important operating variables on any Lamella clarifier.

As solids settle across the plates, they travel downward into the sludge hopper. That accumulated sludge must be withdrawn at an appropriate rate.

The original Parkson operating instructions discuss adjusting sludge withdrawal according to the percentage of solids entering the clarifier. They also describe timer-controlled sludge pumps as one method of obtaining the desired average withdrawal rate.

This is still a very useful operating concept.

If the sludge withdrawal rate is too low, the sludge blanket can rise inside the hopper.

Eventually accumulated solids can interfere with clarification and be carried into the effluent.

Parkson's original troubleshooting section specifically identifies an incorrect sludge withdrawal rate as a potential cause of high suspended solids in the clarified effluent.

For older units, we generally recommend that operators monitor sludge accumulation closely rather than simply assuming that an existing timer setting is still correct.

Changes in production, chemistry, influent solids concentration, polymer dosage, or wastewater flow can all change the amount of sludge being generated.