Stormwater Treatment

Ecotechnic Stormwater Treatment

Environmentally friendly treatment


Rainwater from sealed surfaces is often contaminated with pollutants. The range ranges from hydrocarbons and road abrasion to heavy metals dissolved and bound in sediments. Here, too, the sedimentation of the particulate-bound pollutants is usually insufficient to fall below the acceptable limit values for seepage or direct discharge into a flood. This is because dissolved substances also have to be removed from the rainwater.

Depending on the intensity of the use of traffic areas, this pollution can be so great that direct seepage would endanger groundwater and soil. Pre-treatment of rainwater may become unavoidable, as soil and water protection must be taken into account when seepage occurs. Rainwater from metal roofs can also partly wash out high concentrations of metal ions.

Working Principle

  1. The stormwater from the area to be drained is fed in at the lower end of the shaft. The water is tangentially deflected by the deflector.
  2. Here, the sedimentation of particles and in particular the sand fraction takes place in a hydrodynamic separator on account of turbulent secondary flows in a radial laminar flow regime.
  3. The particles are caught in a sludge trap underneath the system via an opening in the lower part of the cleaning shaft. The sludge trap is evacuated at intervals.
  4. There are four filter elements in the centre of the cleaning shaft, with which the fines are filtered in an upward flow process and the majority of the dissolved pollutants are precipitated and adsorptively bound. The filter can be backwashed from above and is easy to replace in case it is fully silted up.
  5. The filter elements are easy to remove via the existing shaft opening.
  6. The clean water is located above the filter elements; it passes through an oil separator and then flows via the outlet into the seepage or a surface water.


Approvals and Verifications

  • General building authority approval from the DIBt for seepage Z-84.2-4
  • Tested in accordance with NRW regulations, on LANUV list
  • Approved in accordance with the Bavarian Water Act for metal roof run-offs
  • Independent in-situ measurement results from different countries are available
  • Tested in accordance with the NJDEP protocol
  • Rainwater Filtration with ecoStorm plus

    • Cleaning of street drains with ecoStorm plus
    • ecoStorm plus for cleaning rainwater from metal roofs



    The Hydroshark sedimentation plant reliably removes filterable solids (TSS) from the rain runoff. It thus protects bodies of water and seepage systems.

    The water is initially fed tangentially into the centre of the system, where the sedimentation of the solids takes place by means of the so-called teacup effect. The solids sink into the sludge trap below, which is hydraulically separated from the treatment chamber by flow breakers so that remobilisation of the settled particles cannot occur in case of heavy rain. The water subsequently flows evenly upwards in the outer ring of the system.

    A serrated weir ensures that no short-circuit flows arise in the system and that the most homogeneous flow possible prevails. The water then subsequently flows over the serrated weir into the outlet. Lightweight substances such as oils or pollen are effectively retained as they cannot pass through the separation wall. There is no height offset between inlet and outlet. The system cannot block.

    The system can be used for all areas, from roof areas to traffic areas and industrial areas. The cleaning performance is designed such that the requirements of M 153, the future A 102 and the NRW separation decree are met.

    Working Principle

    1. The water flows tangentially into the centre of the hydrodynamic separator.
    2. Solids settle at the bottom, floating matter remains on the surface of the water.
    3. The solids are collected in the sludge trap, which is separated hydraulically from the treatment chamber by flow breakers and a grating so that no re-dissolving occurs.
    4. The water rises evenly at the side walls.
    5. The cleaned water flows over a serrated weir and is collected via in a ring chamber and then transported to the outlet.
    6. The water drains off.


    Approvals and Verifications

    • Transmission value according to DWA M 153 D = 0.35 (field D25) for connectable areas according to table, rcrit = r(15.1), here with 150 l/(s·ha) for simplification
    • Transmission value according to DWA M 153 D = 0.50 (field D24) for connectable areas according to table, rcrit = 45 l/(s·ha)
    • Tested in the laboratory on the basis of the requirements for DWA A 102 with TSS63 (retention of TSS63 > 55 % for Category 2 areas, >70% for Category 3 areas)
    • Laboratory test according to NRW regulations decree with TSS200 according to the modified DIBt method
    • Tested according to the American NJDEP protocol