international - wwt-online.de
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international - wwt-online.de
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WASTEWATER Object report<br />
The new three-bla<strong>de</strong> submersible mixers with optimised flow properties used in the<br />
Eisbiegel wastewater treatment plant ensure that the fluid is homogenised optimally<br />
and efficiently, whilst running smoothly and with great reliability. Image 6<br />
improve the overall efficiency<br />
of the system.<br />
Wilo submersible mixers improve<br />
efficiency by around ten<br />
percent compared to the mo<strong>de</strong>ls<br />
that they have replaced. The<br />
large propeller diameter and<br />
low rotation speeds make it possible<br />
to achieve enormously<br />
high thrust values at the same<br />
time as having a low power<br />
consumption. Their modular<br />
set-up means that the submersible<br />
motor, gear unit and propeller<br />
can be precisely adapted to<br />
the required performance data<br />
and basin geometries. The use<br />
of highly economical asynchronous<br />
motors, which are in line<br />
with the new European energy<br />
efficiency class IE3 for asyn-<br />
chronous motors, as well as<br />
frequency converters for infinitely<br />
variable adaptation of the<br />
hydraulic output to the load<br />
status <strong>de</strong>livers an additional reduction<br />
in the units' energy<br />
consumption.<br />
Operational reliability<br />
and energy saving<br />
Regular operation was restored<br />
in the facility's activated-sludge<br />
tanks equipped with Wilo submersible<br />
mixers and proved so<br />
convincing for the operators of<br />
the wastewater treatment plant<br />
that they invested in additional<br />
mo<strong>de</strong>rn mixers. The outstanding<br />
results of the test phase<br />
prompted the <strong>de</strong>cision to launch<br />
a rolling programme of equip-<br />
About WILO SE<br />
WILO SE with headquarters in Dortmund, Germany, is one of<br />
the leading manufacturers of pumps and air-conditioning technology<br />
for water supply, sewage and drainage systems. Wilo<br />
is represented by almost 70 subsidiaries all over the world<br />
and employs about 6,000 people. Its turnover in 2009 was<br />
€ 926 million.<br />
ping other activated-sludge<br />
tanks with new submersible<br />
mixers from Wilo as well. As a<br />
result, 24 out of the 32 submersible<br />
mixers were replaced by<br />
new units over the subsequent<br />
years.<br />
This not only significantly improved<br />
plant operation, but also<br />
<strong>de</strong>livered a marked reduction in<br />
energy costs. Energy consumption<br />
before the replacement was<br />
running at 1.61 W/m3 of sewage,<br />
and was cut to 0.78 W/m3 due to<br />
the conversion measures.<br />
This represents a reduction of<br />
0.83 W/m3 which amounts to a<br />
saving of 52,000 Euros per year,<br />
assuming an energy price of<br />
approx. 0.15 €/kWh.<br />
Plant optimisation<br />
with new recirculation<br />
pumps<br />
In 2006, positive experience<br />
with the newly purchased slowrunning<br />
submersible mixers<br />
prompted HVG to replace the<br />
four recirculation pumps used in<br />
the sewage treatment process<br />
with Wilo units as well. These<br />
feed micro-organisms back into<br />
the purification cycle.<br />
The propellers of the recirculation<br />
pumps have optimised flow<br />
properties and are self-cleaning,<br />
wich allows for highly energyefficient<br />
operation. At the same<br />
time, sewage and activated<br />
sludge can be pumped very<br />
gently by a special bla<strong>de</strong> <strong>de</strong>sign.<br />
These pumps are produced according<br />
to a modular principle<br />
and are optimally adapted to the<br />
requirements of the Eisbiegel<br />
wastewater treatment plant. The<br />
motor, gear unit and propeller<br />
are combined in such a way as<br />
to ensure operation is as gentle,<br />
efficient and reliable as possible,<br />
as well as allowing the operating<br />
costs to be optimised<br />
further.<br />
Conclusion:<br />
Operation improved,<br />
costs lowered<br />
Its investments in more efficient<br />
and reliable mixer and pump<br />
technology has allowed the<br />
HVG to significantly reduce the<br />
operating costs of the Eisbiegel<br />
wastewater treatment plant. The<br />
robust configuration of the submersible<br />
mixers and the sturdier<br />
lowering <strong>de</strong>vices have ren<strong>de</strong>red<br />
downtimes and complicated<br />
maintenance procedures a thing<br />
of the past, thereby significantly<br />
reducing the costs of maintenance.<br />
Furthermore, the three-bla<strong>de</strong><br />
propellers with their optimised<br />
flow properties compared to the<br />
old mixers produce a significant<br />
improvement in the homogenisation<br />
of the fluid in the activated-sludge<br />
tanks, and above<br />
all they perform more reliably<br />
in operation. In addition, using<br />
the latest motor and control<br />
technology has resulted in the<br />
mixers operating with optimised<br />
efficiency and a significant<br />
reduction in energy consumption.<br />
CONTACT<br />
WILO SE<br />
Nortkirchenstraße 100<br />
44263 Dortmund<br />
Tel.: 0231/4102-0<br />
Fax: +49 (0) 2 31 / 41 02-7575<br />
E-Mail: wilo@wilo.com<br />
www.wilo.com<br />
36 INTERNATIONAL 2011
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