• Schwimmende Tauchwand Typ SWTW
  • Schwimmende Tauchwand Typ SWTW
  • Schwimmende Tauchwand Typ SWTW
Coarse solid retention

Floating Scum Baffle Type SWTW

Many modern municipal wastewater treatment systems are based on combined sewer systems, where rainwater and domestic wastewater are collected. Especially in case of high water arise like during extreme storm water condition, it is necessary to intercept this water into a receiving stream to protect the wastewater treatment plant against overloading. The easiest and most cost-efficient solution are retention basins at the pre-clarifier, placed in front of the real wastewater treatment plant.

Coarse solids can be discharged into pre-clarifier in the form of suspended or floating matter during the relief process. To prevent this, relief structures are equipped with baffles to retain floating matter and solid matter. However, conventional fixed baffles are not able to fully serve this purpose.

The floating scum baffle type SWTW of BIOGEST® AG is used for targeted retention of solids on relief thresholds in separating / discharge structures of combined sewage systems.

SoLid retention of floating matters at stormwater overflows and cso outlets


The floating body of the floating scum baffle type SWTW-V (vertical) is in dry weather in lowest position on the sole of the building. The floating body of the floating scum baffle type SWTW-R (radial) is in dry weather located on the overflow wall. Starting from approximately a water level of 400 mm, the floating body swims upward. Two-thirds of the baffle height shall be under the water level and one-third above the water level. As a result, the floating particles effluent over the threshold in the receiving water ways is largely prevented.
Schritt 1

Step 1

Due to the low position of the baffle, the floating particles will be separated with the beginning of rising water level.

Schritt 2

Step 2

The floating particles swim up with the rising water level. Likewise, the baffle swims up with the rising water level and retents the floating particles on the foul side.

Schritt 3

Step 3

During overflow discharge the floating baffle is at highest position and hold back the floating particles effectively on the foul side. The water discharge over the overflow weir happens without discharge of floating particles.

Schritt 4

Step 4

The water level drops again. The floating scum baffle sinks with the water level and the floating particles remains on the foul water side.

Schritt 5

Step 5

The floating scum baffle is in low end position again.

The advantages

  • Effective retention of floating solids by floating baffle
  • Compact application due to modular arrangement
  • Effective retention of solids due to floating baffle acting with the water level
  • Installation possible even through very small access openings
  • Operation without external energy
  • High flexibility with regards to different geometries by adaptive system versions
  • Ideal for large and fluctuating water levels
  • Adjustable immersion depth with water ballast possible
  • Excellent price-benefit-ratio
  • Low maintenance