Efficient purification of waste waters
Actor: Environmental services of the Helsinki region, Water (HSY Vesi)
Category of actor: Municipality
Location: Hernepellontie 24, Helsinki, Finland
Theme of action: Waste waters
Description:
The water treatment plant of Viikinmäki has set for itself higher cleaning targets than the legislation. Solid substances, substances which consume oxygen, 95 percentage of phosphorus and 90 percentage of nitrogen are removed from the waste water.
In the waste water treatment plant, mainly built inside of rock, the waste waters of about 800 000 inhabitants and the regional industry are treated. The treated waste water is led in a rock tunnel to a distance of eight kilometres from the southern point of Helsinki to the sea in front of Katajaluoto, depth of more than 20 meters.
Benefits
According to the 2008 purification results the waste water treatment plant purifies phosphorus 0.08mg/l more that the term of the license requires. The annual amount of treated waste water is 100 million m³. This means that 8 tonnes less of phosphorus is getting into the Baltic Sea every year.
|
|
Environmental licence |
Demands of the EU |
Cleaning result of the year 2008 |
|
BHK7 |
< 10 mg/l > 95 % |
< 30 mg/l > 70 % |
6,7 mg/l 97 % |
|
Phosphorus |
< 0,3 mg/l > 95 % |
< 1,0 mg/l > 80 % |
0,22 mg/l 96 % |
|
Nitrogen |
> 70 % |
< 10 mg/l > 70 % |
87 % |
BHK7 describes the amount of the oxygen consuming organic dirt material in the waste water. The phosphorus and the nitrogen are elements which make water systems eutrophic.
Background and legislation
The Urban Waste Water Treatment Directive of the European Union defines the minimum level of the waste water purification. However, Finland has its own higher demands for the level of the waste water treatment (Vesioikeuden jätevesienlaskulupa 264/1961). The environmental license for waste water treatment plant of Viikinmäki specifies the institution’s purification demands. It also gives regulations for the emissions released into the air and for the solid waste. The valid treatment obligations of the waste water treatment plant are its immediate and concrete objectives.
The authorities follow the execution of the treatment demands using the annual and quarterly reports. Furthermore the waste water purification plant of Viikinmäki is obligated to achieve the quality objectives laid down by the city council of Helsinki in its Baltic Sea regulation.
Additional Information:
Tommy Fred
Waste water treatment
Director of the department
Environmental services of the Helsinki region (HSY)
tommy.fred (a) hsy.fi