Dortmund fountain
A Dortmund well (English: Dortmund tank or hopper-bottom tank ) is a settling tank that is used in a sewage treatment plant for the secondary treatment of wastewater . It differs from other sedimentation basins in that it is designed as a deep funnel in which the flow takes place vertically instead of horizontally. The name results from the fact that the use of this design was first mentioned in Dortmund in 1887 .
Layout and function
The Dortmund tank consists of a funnel-shaped basin through which the wastewater to be treated flows vertically from bottom to top . In the basin there is sedimentation of the sewage and activated sludge due to the different densities of the water and the sludge that settles on the walls of the basin. The flow rate of the water decreases due to the expansion upwards, whereby the solids contained sink down and slide on the sloping walls into the sludge collecting space. Due to the construction with a wall inclination of about 60%, the sludge slides completely down and is collected in the tip of the funnel, here it can be sucked off without additional mechanical collectors, which are necessary in a horizontally arranged basin. The separated material can then be fed to a sludge treatment.
commitment
These wells , which are very complex and expensive due to their depth , are now only implemented in small systems. The hydraulic efficiency is around 60%.