Sewage Purification and Sludge Treatment Systems Sewage Treatment by act50979


									Sewage Purification and Sludge Treatment Systems
Sewage Treatment Plant, Unterföhring, Extension for Phosphorus and Nitrogen Elimination

Project period                             1993 - 2000

Construction cost                          600 000 mio. € approx.

Services provided                          Project planning, tendering site supervision, construction management
                                           and commissioning, planning and construction management of the proc-
                                           ess, procedure and electronic instrumentation technology

Technical details                          Extension of the existing mechanical-biological sewage treatment plant with
                                           anaerobe sludge treatment for the elimination of phosphorus and nitrogen
                                           Size of extension: 20 000 population units

This combined mechanical and bio-
logical treatment plant went into
operation in 1981.
In 1993, the up-grading of the legal
and water-management require-
ments governing the elimination of
nutrients called for the installation of
a simultaneous precipitation plant,
followed in 1997 by the adoption of
measures to reduce the nitrogen
After inspecting the different plant
extension alternatives for nitrogen
elimination for technical and com-
mercial viability, the municipality
decided in favour of the carrier-
material method. The use of carrier
material makes it possible to in-
crease the amount of micro-
organisms in each tank, thereby
improving the purification power of
the sewage plant. This means that a
reduced tank volume is sufficient for
purposes of nitrification.
The extra tank volume made avail-
able in this way was separated off by
means of stainless steel walls, and is
being used as a preliminary denitrifi-
cation tank to further increase the
removal of nutrients. Apart from this,
the preliminary sedimentation tank
was made smaller, with part of it
being used for denitrification and
biological elimination of phosphorus.
The carrier-material method meant
that structural extensions in the form
of an extra activated sludge tank
could be dispensed with.
The extension of the sewage plant
for purposes of nitrogen elimination
furnishes values well below the run-
off works required by water man-
agement regulations, resulting in an
additional reduction in the amount of
effluents discharged.

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