During the operation of wastewater treatment systems, many businesses encounter situations where the effluent TSS exceeds regulations, settling tanks are frequently overloaded, or treatment capacity needs to be upgraded when production output increases. However, building a new settling tank often requires a large area, high investment costs, and can affect existing production activities. In these cases, the Lamella settler is considered an effective retrofitting solution to help increase sludge separation capacity, upgrade treatment capacity, and optimize construction area without needing to significantly change the structure of the existing system.
A Lamella Settler is a system consisting of multiple settling plates arranged parallel to each other at a specific inclined angle inside the settling tank. These plates create multiple individual settling surfaces, significantly increasing the effective settling area without expanding the tank size.
Unlike traditional settling tanks that only use a single settling plane, Lamella technology divides the water flow into multiple thin layers moving between the settling plates. This shortens the settling distance of the sludge particles, thereby improving sludge separation efficiency and increasing the treatment capacity for the system.
Currently, Lamella settlers are commonly installed in physicochemical settling tanks, post-coagulation/flocculation settling tanks, or water supply treatment facilities with a high suspended solids content.
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Lamella settler
The operating principle of the Lamella settler is based on increasing the settling surface area inside the tank. Wastewater, after the coagulation or flocculation process, is directed into the area containing the inclined settling plates.
As the water flows upward between the plate gaps, sludge particles with a specific gravity greater than water collide with the plate surface and settle. Under the influence of gravity, the sludge particles continue to slide down along the settling plate surface towards the bottom of the tank to be collected and treated.
Meanwhile, the water, after being separated from the sludge, continues to flow upward and is collected in the water collection trough. By creating multiple parallel settling surfaces, the treatment efficiency of the tank is significantly improved compared to conventional settling methods.
In practice, the inclination angle of the settling plates is usually designed around 55 – 60° to create favorable conditions for the sludge to slide down to the tank bottom. The distance between the settling plates will be calculated based on wastewater characteristics, surface loading rate, and the design flow of each system.
Thanks to the mechanism of creating multiple parallel settling surfaces, the Lamella settler can increase the effective settling area many times over compared to a traditional settling tank of the same size. This is why this technology is often chosen in projects to retrofit or upgrade the capacity of wastewater treatment systems when construction land is limited.
In many wastewater treatment systems, the settling tank plays a crucial role in separating sludge and reducing suspended solids before the water is led to subsequent treatment units. However, when the wastewater flow rate increases or wastewater characteristics change, traditional settling tanks often begin to reveal certain limitations.
A common cause is that the settling surface area no longer meets the actual load. When the flow velocity increases, unsettled sludge particles are carried by the water flow out of the tank, leading to high effluent TSS. In many cases, businesses want to increase treatment capacity but no longer have the land available to expand or build new settling tanks.
This is also why many current wastewater treatment systems choose the solution of installing Lamella settlers to increase the useful settling area without significantly changing the existing structural works.
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Lamella settler in wastewater treatment
When selecting Lamella settlers for a wastewater treatment system, besides the manufacturing material, businesses need to pay attention to factors such as inclination angle, distance between settling plates, height of the settling block, and chemical resistance of the material. Inappropriate selection can reduce settling efficiency or cause clogging during operation.
In practice, the inclination angle of the settling plates is usually designed from 55 – 60°. This is the angle range that helps sludge particles easily slide down to the tank bottom under the influence of gravity, limiting the accumulation of sludge on the surface of the settling plates.
The distance between the settling gaps directly affects the sludge separation efficiency. If the distance is too small, the system is prone to sludge clinging and clogging. Conversely, if the distance is too large, the useful settling area will decrease, and the treatment efficiency will not be as expected.
Based on structure:
Based on materials:
Among them, PVC honeycomb settling plates are currently widely used due to their lightweight, good corrosion resistance, reasonable price, and convenience during installation.
Load-bearing capacity and wastewater characteristics In addition to the basic parameters, the selection of settling plates also needs to consider the design flow rate, surface loading rate, influent TSS content, and floc characteristics of each system. Proper calculation right from the design stage will help optimize settling efficiency and extend the lifespan of the structure.
Cost-effective and efficient wastewater treatment with Lamella settlers
Not all wastewater treatment systems are required to install Lamella settlers. However, this solution is particularly suitable in the following cases:
In many wastewater treatment system retrofitting projects, adding Lamella settlers often helps improve settling efficiency without the need to build a new tank, thereby significantly saving investment costs and construction time.
In cases where wastewater has a high suspended solids content, businesses can refer to the article "What are TSS and Turbidity in Wastewater? Meaning, Relationship, and Effective Treatment Methods" to better understand the causes and solutions for controlling TSS in wastewater treatment systems.
An increase in effluent TSS is not always caused by operational incidents or a lack of chemicals. In many cases, the cause comes from the existing settling structure no longer meeting the actual load.
Businesses should consider the solution of adding Lamella settlers when one or more of the following signs appear:
In these cases, adding Lamella settlers often helps increase the effective settling area many times over compared to conventional settling tanks of the same size, thereby improving sludge separation efficiency and optimizing the system's treatment capacity.
In reality, Lamella settlers are often installed in wastewater treatment facilities with a high suspended solids content or those generating many flocs after the coagulation and flocculation process.
Some common application areas include:
Applying Lamella settlers in these areas helps increase sludge separation efficiency, reduce the load for downstream structures, and improve the effluent water quality of the entire system.
Wastewater treatment system using Lamella settlers
One of the biggest advantages of the Lamella settler is the ability to increase settling efficiency without expanding the construction area. By increasing the useful settling area, the system can treat larger flow rates within the same tank volume.
Furthermore, this technology also helps improve TSS removal capacity, reducing the amount of sludge entering downstream treatment facilities such as biological tanks, filtration tanks, or membrane filtration systems. This contributes to stabilizing effluent water quality and reducing operating costs.
For projects needing retrofitting or capacity upgrades but lacking expansion land, adding Lamella settlers is often a more effective and cost-saving solution than building new settling tanks.
Some outstanding benefits of the Lamella settler include:
Besides its outstanding advantages, Lamella settlers still have some limitations that need to be considered during design and operation.
The settling efficiency of the system depends heavily on the quality of flocs formed from the preceding coagulation and flocculation stage. If the flocs are too small or unstable, the sludge separation capacity will decrease significantly.
Additionally, the settling plates can become fouled or scaled after a long period of operation, especially for wastewater sources with high oil, grease, or organic content. Therefore, periodic cleaning must be performed to maintain treatment efficiency and avoid flow-clogging phenomena.
Lamella settlers are also not a complete replacement for the coagulation and flocculation process. For wastewater sources with very small particle sizes or poor settleability, treatment efficiency will depend greatly on the quality of the upstream pre-treatment stage.
It can be seen that the Lamella settler is an effective retrofitting solution that helps improve sludge separation capacity, increase treatment capacity, and reduce the need for construction area expansion for wastewater treatment systems. However, to achieve optimal efficiency, selecting the settling plate configuration, calculating the settling load, and evaluating wastewater characteristics need to be carried out synchronously right from the system design or retrofitting stage.
If your business is experiencing an overloaded settling tank, unstable effluent TSS, or needs to upgrade the wastewater treatment system but is limited in construction area, the engineering team of Dai Nam Environmental Solutions Co., Ltd. is ready to survey, evaluate the current situation, and propose suitable retrofitting solutions to optimize treatment efficiency as well as investment costs
