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Waste Water Treatment in Finland

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Waste Water Treatment
in Finland
Suvi Holopainen
History of Waste Water
Treatment in Finland
First waste waters were piped to water
system without purification.
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It lead to water pollution in water systems
close to cities.
The first waste water plants were built in
Lahti and Helsinki in 1910.
History of Waste Water
Treatment in Finland
In the 1920s and 1930s, sewers and waste
water treatment plants were also built in smaller
cities.
However, only small part of waste waters was
treated those days and water pollution of water
systems close to cities was a big problem
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The pollution situation of water systems was the worst
at the beginning of the 1970s.
Mechanical waste water treatment plants were
built in the 1960s but biological purification
systems became more common in the 1980s
Waste Water Treatment in Finland
Nowadays
80% of inhabitants live within centralized
sewerage system and waste water
treatment.
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In all population centres, waste waters are
treated chemically and biologically
Approximately 20% of the inhabitants live
in houses that are not connected to
centralized sewerage system
Waste Water Treatment in Urban
Areas
There are approximately 550 waste water
purification plants in Finland
The most common method of purification
is biological-chemical simultaneous
precipitation
Waste Water Treatment in Urban
Areas
Steps of waste water treatment:
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Screening
Separation of grease and sand
Preliminary settling
Aeration
Final sedimentation
Waste Water Treatment in Urban
Areas
Nitrogen removal
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The most common method is biological
process, which bases on nitrification and
denitrification.
Phosporus removal
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Chemical treatment is the most common
method.
Waste Water Treatment in
Communities
Sludge
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The treatment of the sludge constitutes 30%
of costs of waste water treatment plant.
Approximately 1 million cubic meters of
sludge forms in public waste water treatment
plants in one year.
After treatment sludge can be used as
gardening and landscaping purposes.
Waste Water Treatment in Urban
Areas
Results:
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97% of organic matter of waste water and
95% phosphorus was removed (2005).
The biggest challenge will be the reduction of
nitrogen
Nowadays, approximately approximately 54 % of
nitrogen can be removed.
Waste Water Treatment in Rural
Areas
20% of Finnish inhabitants live in houses,
which are not connected to the
centralized sewerage system
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Waste water treatment systems of those
houses are often obsolete or otherwise
ineffective
Waste Water Treatment in Rural
Areas
Thanks to legislation, waste water treatment in
rural areas will be improved notably over coming
years.
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According to the Decree, at least 90% of organic
matter should be removed from waste water, as well
as over 85% of total phosphorus and over 40% of
total nitrogen.
The waste water systems of buildings that have been
completed before 2004 must fulfil new standards by
1.1. 2014 while the waste water systems of new
buildings must fulfil those standards immediately.
City of Helsinki
Helsinki :
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The capital city of Finland
About 570 000 inhabitants
Located on the coast of
the Baltic Sea
All waste waters of
Helsinki are treated in
one WWTP called
Viikinmäki.
Viikinmäki Waste Water Treatment
Plant
Viikinmäki treats waste water of over one
million inhabitants.
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All waste water from Helsinki and the runoff
water from downtown area.
All waste waters of Järvenpää, Kerava, Sipoo
and Tuusula.
Part of waste waters of Vantaa.
Viikinmäki Waste Water Treatment
Plant
Many benefits have been achieved by
concentrating waste water treatment on
one plant:
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Results of the treatment have improved.
Major economies have achieved.
Waste Water treatment Process at
Viikinmäki
Viikinmäki is a activated sludge plant.
Waste water treatment consists of three
parts:
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mechanical
chemical
biological purification
Waste Water treatment Process at
Viikinmäki
Sludge Processing at Viikinmäki
In thermal energy, Viikinmäki is totally selfsufficient and about 50% self-sufficient in
electricity.
All that sludge is composted on the composting
site called Metsäpirtti
Conclusions
Public waste water treatment works rather
well
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In future, the biggest challenge will be the
reduction of nitrogen
Waste water treatment in rural area has
more problems
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Situation will improve in the near future,
thanks to legislation.
Thank you for your
attention
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