Blog Article

Considerations to bear in mind when covering a lamella clarifier.

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In some facilities, lamella clarifiers need to be covered. This is usually done for aesthetic or practical reasons: they are covered not to be seen or to avoid bad smells. Once the areas likely to generate bad smells have been covered, the gas has to be captured and sent to a gas scrubber (deodorization).

When installing lamellar modules in a covered clarifier, you need to consider the following:

    • All supporting materials and screws must be made of anti-corrosive materials because they will be exposed to hydrogen sulphide that is highly corrosive. Therefore, avoid carbon steel, galvanized steel, aluminum or AISI-304 stainless steel.
    • The design of the clarifier must take into consideration that the modules won’t be easy to clean because to do so, operators will have to remove the cover, or part of it. Hence, the need of designing a lamella clarifier that does not require cleaning on a monthly basis.
    • Access to the inside of the clarifier must be made easy, to be able to clean it or repair the scraper in case of breakdown.


  • It is necessary to calculate the supporting structure correctly to prevent it from collapsing under the weight of accumulated sludge. The difficulty of removing the cover might affect the cleaning of modules, which might not be carried out periodically, leading therefore to sludge accumulation inside. Our duty as technicians is to ensure that the installation does not become obsolete.
  • The scraper cannot be made of carbon steel and has to be particularly robust and reliable. Account has to be taken of the fact that in case of failure, the operator will not know it because he cannot enter the clarifier. He will therefore rely on alarm systems, such as torque limiters or rectangular scrapers guidance systems. This point is of utmost importance: if the scraper fails and the operator does not realize it, the sludge will accumulate until it blocks the lamella. If the structure is not properly calculated, the installation will collapse.
  • Thompson channels collecting clean waters also have to be made of stainless steel or anti-corrosive materials.



24 Nov, 16



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