Preliminary treatment

Preliminary treatment

The entire UWA program ranges from engineering/ planning services, analyses and capacity optimisation to individual turn-key plant construction services.

UWA is a reliable, experienced partner possessing numerous reference objects in Germany and abroad.

Take advantage of our know-how in terms of wastewater/ sewage treatment. We would be pleased to inform you about our products or respectively submit you an offer.

Belt-type filter, filter screens / step screens / rotary screens

Our products enable a trouble-free integration into existing systems or plants - thanks to technical innovations and process improvements. For the preliminary treatment of wastewater in inlet basins we offer customised:

  • Belt-type filters, filter screens
  • Step screens
  • Rotary screens

The entire system is made of stainless steel in order to guarantee an optimal corrosion protection. Furthermore, they are equipped with fully-automatic control system with touch panel.

The step screen represents a further development of the belt-type filter. It is also a rake screen, but contrary to the normal belt-type filter it is equipped with perforated plate elements arranged in a stepped version. This screen ensures a high degree of separation by means of these perforated plate elements. Further advantages of the step screen is the minimisation of rolling formations at the screen as well as the omission of unwanted crushing of screenings caused by shearing effects of the lamellas. The driving rate as well as the screen rate can be adjusted to the volume of the incoming wastewater/sewage. The step screen can also be used in case of very high water levels and is especially suitable for combined wastewater and sewage systems. Furthermore, it is equipped with a system program for rainy days.

The rotary screen essentially consists of a slotted screen basket and a screw conveyor. The slot widths are designed according to the hydraulic requirements. Alternatively, the width can be selected. The slot screen is automatically cleaned by a spraying stick. Organic materials can be flushed out in the screw area (option). The separated are drained and pressed in the press zone.

The rotary screen can be adjusted to each kind of channel or basin/ tank. There is no wear of the screening system.

Grit washing systems


UWA grit washing systems are used in order to separate solid matter from liquid material within the wastewater/ sewage treatment system.

The grit washing systems are designed as grit classifiers and carry out washing and dewatering processes. The grit-water mix is separated in three different fractions:

  • Washed and drained grit
  • Wastewater/ sewage water, overflow water
  • Organic water

Reliable results with a high separation and cleaning rate can be obtained by means of an effective grit washing with a three-stage process.

The further treatment of the wastewater/ sewage in downstream treatment stages can thus be effected failure-free.

The grit classifier can be equipped with a surface heating in case of an outdoor operation.

Sewage intake station


The sewage intake station is completely closed and serves as a preliminary treatment of faecal sludge and sewage by screening non-biodegradable solid matters and impurities. The intake station can optionally be equipped with an aerated grit chamber for the direct injection into biology basins or digesters. This is required according to the German ATV-Arbeitsblatt A123. Its compact construction design even enables a retrofitting of existing wastewater/ sewage treatment plants. The stations can be adjusted to all requirements thanks to the integrated UWA step screen with adjustable hole size. The stations are directly fed by the tank lorry and are equipped with a control system. This control system enables an automatic control from the total process to the drop pit.

Process advantages

  • Optimal screening of non-biodegradable material
  • Avoids blockages and clogging
  • Better quality of surplus activated sludge
  • Highest operational reliability

Our intake stations made of stainless steel can additionally be equipped with an automatic sewage identification system including a registration unit.

Washing press for screenings


This unit presses the material discharged from the screen and simultaneously separates the organic matter from the screenings. The washing press is equipped with a specifically designed intensive washing zone. Optionally, we can fit the washing press with a washing facility via the worm shaft, a replaceable press zone as well as with a specific program for rainy days. The latter enables a proper reaction towards impact loads in case of heavy rain. Spare parts can be replaced in a trouble-free and cost-effective way. The washing water with the separated organic material is recirculated into the treatment processes. The supply pipeline can be manifoldly adjusted according to the required transport routes. The separated organic material can be biologically degraded by means of a recirculation into the wastewater/ sewage treatment plant. The washing press can also be installed outside. In this case the hopper (optionally even the supply pipeline) is equipped with an electrical heating.