We get asked a lot of questions about water and wastewater treatment, mass transfer and cooling tower components. Here are the most popular.

You did not find an answer to your question? Please contact us per mail at or by phone: +49 2233 39828 0. We are happy to help.


Our many years of experience as manufacturer of cooling tower installations show that many users are not aware of the possibility of using PP instead of PVC as a material for fills and drift eliminators. In as early as the 1980s, however, we found a good alternative in PP. Many of our customers have used it successfully in cooling towers for decades. After polyethylene, PP is the second most commonly used plastic.
Our brochure presents the properties of the two polymers and offers a better understanding of PP as an alternative to PVC: Brochure PROPERTIES OF POLYMERS PP AND PVC 
Although this brochure mainly focuses on cooling towers, certain aspects are interesting for water and wastewater applications as well. Have a look!


We recommend inclining against the flow direction for 3 important reasons:

  1. When installing the lamellas against the flow direction, the size of the influent zone is larger, which improves calming of the flow and reducing the flow velocities.
  2. Any preferred flow currents are deflected from the lamella inclination and the sludge particles directly hit the lamellas. Thus, they settle and slide down the lamellas.
    In installations in flow direction, the particles enter the lamella channels without any resistance, which may result in sludge passing the channels without settling on the surface. This would mean there is only little or no sedimentation of the sludge.
  3. Descending sludge from the lamellas is rather taken away from the lamellas than pushed back into them.

Looking at typical designs of lamella settlers around the world, we find that the majority follows this idea.


Unfortunately, no general statement can be made in this regard. It depends on the individual situation and a variety of factors:

  1. When you intend to use lamella plates in order to have a low footprint clarifier, for example, the square tank will make it more cost effective since lamella modules, launders and a support structure can be installed more easily.
  2. To reach more capacity of existing round clarifiers our lamella modules will also be more cost effective than building new clarifiers.

Please contact us for more information in regards to your specific situation!


From their design TUBEdek® lamellas are self-cleaning. Settled substances slide down the inclined profiles into the sludge collection section by gravity. One important step for an efficient sedimentation is to match upstream and settling processes.
However, sometimes due to certain circumstances scum and floating sludge may occur. Sludge that remains too long in the bottom of a clarifier may become biologically active and generates gas bubbles, which lift sludge upwards. This will deteriorate the unit’s performance.
The following measures can be taken against this effect:


Check the performance of the upstream processes. Maybe there are possibilies to make adjustments in order to prevent floating particles. This is the most important point as for example improved grease removal or aeration strongly affect building of scum and floating sludge. Optimizing upstream processes is the best measure to achieve an efficient settling performance.

Apart from that, you can do the following:

  1. Increase the frequency of sludge removal from hopper
  2. Discharge the sludge more frequently from the clarifier
  3. Increase hydraulic to design value
  4. Install a skimmer, which retains scum.
  5. Install scum-removing devices
For more information, please contact us.


From their design TUBEdek® lamellas are self-cleaning. Settled substances slide down the inclined profiles by gravity into the sludge collection section. One important step for an efficient sedimentation is to match upstream and settling processes.

Nevertheless, sometimes flocs are discharged upwards from the settlers, deposit as sludge on the wall, the interspace between the modules or in the dead space between the modules and the wall. Usually this does not influence the operation.

When to act and what to do

You only need to act if the discharge values are disturbed. We then recommend to empty the tanks every 6 months, flush and clean the settlers, with special care to the dead zones.
Do you need some advice in this matter? Contact us at!
Here is some further information: How to clean TUBEdek® quickly and easily.


From their design, TUBEdek® lamellas are self-cleaning. Settled substances slide down the inclined profiles into the sludge collection section by gravity. 

One important step for an efficient sedimentation is to match upstream and settling processes. Otherwise, issues such as plugging may occur.


Plugging may be caused by either design failures and/or insufficient operational and maintenance care
Design failures can lead to:
  • a too high solids load
  • solids tending to cake/stick together or to incrust
  • a too small distance of the sedimentation tubes has been chosen
  • a too small distance between lamella top and launders

Insufficient O&M

  • a too high sludge level
  • rotten sludge that floats as large chips and is carried into the tubes
  • flocs that do not slide down due to deposits



STEP 1: run trials to find the optimum physical and chemical process conditions for the pre-treatment, e.g., mixer speed and type, hydraulic retention time, pH, alkalinity, coagulant, and flocculant dosage.
STEP 2: process concept needs to have some flexibility, e.g., additional dosing points and equipment, some margin regarding the hydraulic retention time, respect design rules. CFD modelling helps with respect to hydraulics, in many cases the chemical requirements are neglected.


The reasons for plugging need to be detected and corrected rapidly. Then, you need to clean the TUBEdek® lamellas. For cleaning and flushing, you lower the water level gradually. Pay attention to the mechanical load of the lamellas and the support structure and immediately flush off larger sludge deposits while lowering the water level. Read a detailed description of how to clean TUBEdek®


As said above, the best measure to provide plugging is a sedimentation process that is well adjusted to upstream processes. Should you need some advice, please contact us at


TUBEdek® lamella settlers need to be cleaned in regular intervals that depend on your application and the condition of the lamellas. The cleaning is easy to do if you observe some guidelines.


As TUBEdek® lamellas are strong and robust you can use pressurized industrial process water to clean them. We recommend using a flat waterjet. Start with low water flow and high pressure and continue with high water flow and lower pressure.
However, you need to be careful: Flushing should never cause vibrations of the TUBEdek® surfaces. Vibrations will cause fine cracks and damage the lamella. Do the flushing with the same attention, as you would clean a car.


We recommend training the cleaning procedure on a spare module to develop a feeling and experience for the flushing before cleaning the installed media.


Typically, you clean TUBEdek® from above. Place planks on top of the lamella. They should fully extend at least over two rows placed side by side. Cleaning TUBEdek® from below is not a regular working procedure as you need to drain the complete tank.
Automatic cleaning of the lamellas does not achieve satisfying results.


  1. Water quantity
  2. Pressure
  3. Angle of impact of the water jet
  4. Distance of nozzle to TUBEdek®
  5. Type of spray nozzle (compact or diffused)


  1. Slowly lower the water level in the sedimentation tank. The water level should be in a range of 20 cm below the lamellas up to the bottom of the lamella.
    Pay special attention to the mechanical load of lamellas and support structure when lamellas are plugged – see chapter ATTENTION WITH PLUGGED LAMELLAS below. Never walk on top of the lamellae when they are plugged!
  2. Always apply the jet in the direction of the lamella inclination
  3. Start to clean with low impact
    – use a diffused nozzle which spreads out the water
    – start with a distance of 1 m or more
    – do not direct the jet on one specific spot for a long time
  4. If the cleaning effect is not sufficient, increase the impact carefully by
    – slowly going closer
    – keeping the jet longer on a particular spot
    – using a compact nozzle that does not spread the water
  5. Work cautiously! If the TUBEdek® material starts to vibrate, reduce the impact!
  6. When you use a C-hose and a large quantity of water is applied, the absolute power of the cleaning can be 4 bars (l/-). With a high pressure cleaning system and a small water quantity, you can apply 40 to 70 bars when the nozzle is at least 30 to 50 cm away.
  7. Don’t try too hard! Sometimes it may be necessary to remove scaling by chemical treatment:
    – lime scaling can be removed with acidic aqueous solution (citric acid at pH3);
    – organics can be removed with caustic aqueous solution at pH10, however, then an acidic rinsing is required afterwards.


When TUBEdek® lamellas are plugged, pay special attention to the mechanical load of the lamellas plus the support structure. Lower the water level very slowly and immediately flush off larger sludge deposits during this process. Depending on how plugged the lamellas are and on the type and height of lamellas, the material may bend too strongly and damage the lamella pack. Do not step or walk on plugged lamellas!
Our experts are ready to give you more detailed advice for your individual installation.
For more information, please contact us at


Yes, you just need to follow five design guidelines:

  1. You need a properly designed sand and grit removal for the fast settling, mostly inorganic, matter. Aerated systems give better results and help in FOG removal.
  2. You need a well matching FOG removal (FOG = Fat, Oil, Grease). In combination with the before mentioned sand and grit removal it builds the pre-treatment unit.
  3. The primary clarifier shall remove all organic matter, mainly by settling, but will also eliminate floating substances. Here our TUBEdek lamella separator will lead to reduced tank space and enhanced settling.
  4. A properly selected scraper system ensures the safe removal of settled organics.
  5. Retention time is key depending on the down-stream processes: BOD removal allows different retention times than de-nitrification.

Do you have any questions? We are ready to help you. Please contact us at or call us +49 2233 39828 0.


In waste water treatment plants, trickling filter processes are one of the least energy consuming methods. Even higher investment costs of a flat trickling filter can be compensated by energy savings during operation. Compared to activated sludge plants, trickling filters can save up to 70% costs in municipal waste water treatment.

The following design parameters influence energy consumption of trickling filters and leave room for optimization:
Water feed by gravity: If possible, implement water feeding by gravity. As result, you do not need additional pumps and therefore energy consumption is lower.
Reduce pumping height: Adjust the water distribution, piping, rotary distributor, height of fill media, support grid, bottom and effluent outlet to achieve minimal pumping height.
Ventilation: Check whether forced ventilation is necessary. Compressors for forced ventilation use a lot of electrical energy and furthermore need to be maintained regularly. You can save these costs by using natural ventilation, which is possible in most cases.
Fill media: Choosing fill media which only need low flushing power may optimize the energy requirements. Just make sure that this does not decrease the performance of the trickling filter.
Recirculation: This is one parameter which significantly influences energy consumption. Depending on influent water quality, recirculation may be necessary to provide sufficient water distribution for the biofilm or – as a side effect – for flushing off the surplus sludge. Furthermore, you can use recirculated nitrate-loaded water for denitrification in the trickling filter or for upstream processes.
We are there for any question you might have. Please contact us!


Do you need more information or answers to any questions?


We offer innovative components and solutions for sustainable processes in heat exchange, water and wastewater treatment and mass transfer applications with respect for the environment. Our professional team works to increase productivity and cost effectiveness in your unique application. If you need a tailor made solution ... We are available for you!