Even when individual elements are connected together, their boundary conditions must be taken into account. BundleTube ensures that internal and external flow conditions are the same for each membrane element. By creating defined downward flow zones within the module, the total installation space required for the modules is significantly reduced.

The challenge

  • In all submerged membrane modules for MBR applications, air is introduced into the modules from below for flushing purposes. This creates an upward flow of sludge.

  • In stationary operation, the rising sludge must also flow down again somewhere. This usually happens outside the modules in so-called downward flow zones. Therefore, sufficient space must be provided surrounding the modules.
  • To reach these downward flow zones the sludge has to flow above the modules from the module centre to the outside of the modules. Depending on the module dimensions, this requires an additional suldge height above the modules, which can be up to 100 cm or more. This additional height also increases the air injection depth and thus the energy requirement for module aeration.

The solution: BundleTube

  • With Membion, each membrane bundle is laterally confined over its entire length by a rectangular tube (BundleTube).
  • The air entering from below thus remains completely trapped in the BundleTube during its ascent and is used effectively.
  • In addition, the membranes are protected by the BundleTube against external influences.
  • The same boundary conditions prevail inside each BundleTube.
  • In order to compensate the sludge upward flow close to each BundleTube, the membrane elements are mounted at a distance during module assembly to create the required downward flow zones within the module. 
  • As a result, Membion need less space surrounding the modules during installation, so that the overall space requirement for the modules is reduced.
  • BundleTube also reduces the flow paths of the sludge above each membrane element to the integrated downward flow zones.
  • As a result, the liquid height above the modules can be significantly reduced (< 10 cm), which also contributes to a reduction in the energy requirement for module aeration.

Downward flow zones between the membrane elements through BundleTube