1. Waste Water Treatment in Finland
Suvi Holopainen

2. History of Waste Water Treatment in Finland
First waste waters were piped to water system without purification.
It lead to water pollution in water systems close to cities.
The first waste water plants were built in Lahti and Helsinki in 1910.

3. 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
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

4. Waste Water Treatment in Finland Nowadays
80% of inhabitants live within centralized sewerage system and waste water treatment.
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

5. 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

6. Waste Water Treatment in Urban Areas
Steps of waste water treatment:
Screening
Separation of grease and sand
Preliminary settling
Aeration
Final sedimentation

7. Waste Water Treatment in Urban Areas
Nitrogen removal
The most common method is biological process, which bases on nitrification and denitrification.
Phosporus removal
Chemical treatment is the most common method.

8. Waste Water Treatment in Communities
Sludge
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.

9. Waste Water Treatment in Urban Areas
Results:
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.

10. Waste Water Treatment in Rural Areas
20% of Finnish inhabitants live in houses, which are not connected to the centralized sewerage system
Waste water treatment systems of those houses are often obsolete or otherwise ineffective

11. Waste Water Treatment in Rural Areas
Thanks to legislation, waste water treatment in rural areas will be improved notably over coming years.
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 while the waste water systems of new buildings must fulfil those standards immediately.

12. City of Helsinki Helsinki :
The capital city of Finland
About inhabitants
Located on the coast of the Baltic Sea
All waste waters of Helsinki are treated in one WWTP called Viikinmäki.

13. Viikinmäki Waste Water Treatment Plant
Viikinmäki treats waste water of over one million inhabitants.
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.

14. Viikinmäki Waste Water Treatment Plant
Many benefits have been achieved by concentrating waste water treatment on one plant:
Results of the treatment have improved.
Major economies have achieved.

15. Waste Water treatment Process at Viikinmäki
Viikinmäki is a activated sludge plant.
Waste water treatment consists of three parts:
mechanical
chemical
biological purification

16. Waste Water treatment Process at Viikinmäki

17. Sludge Processing at Viikinmäki
In thermal energy, Viikinmäki is totally self-sufficient and about 50% self-sufficient in electricity.
All that sludge is composted on the composting site called Metsäpirtti

18. Conclusions Public waste water treatment works rather well
In future, the biggest challenge will be the reduction of nitrogen
Waste water treatment in rural area has more problems
Situation will improve in the near future, thanks to legislation.

19. Thank you for your attention