A good water basin is also another important measure that can reduce the leakage of nitrogen and phosphorus compounds. A water basin is an area where the land is drained of water and the system that transports it to the sea (i.e. brooks, rivers and lakes). If the water is transported over a long and open route, it is possible for the excess nitrogen and phosphorus to be used up by natural Biological processes before it reaches the sea. To try and create a good water basin, the authorities in Schleswig-Holstein in Germany introduced regulations in 1989 prohibiting the use of artificiel fertilizers within 10 metres from a watercourse.
Measures in sewage treatment
In a sewge plant, treatment is a process involving several stages. In one stage, nitrogen cleaning is a priority. With the use of bacteria to bind the nitrogen, the content is drastically decreased in the water that is afterwards discharged into the sea. With modern techniques, the nitrogen content can be reduced by up 70-80%. Unfortunately, the reduction of nitrogen content is a rather complicated proceedure and not used by many of the states bordering the Baltic. Algae is also used to bind nitrogen, whereafter it is strained from the water.
Nitrogen cleaning efforts have shown good results. From certain sewage plants, a reduction of 15% was achieved from between 1985 and 1995. Today, Swedish sewage plants release about 17 500 tons of nitrogen annually into the environment. With the currently planned construction of about 70 sewage plants in Swedish coastal areas, it is expected that the above discharge of nitrogen will be reduced by an additional 4 500 tons annually!
|A splendid outing ?|
|Problems and expectations|
|It was better before"|
|Seawater and soluble salts|
|The sea moves|
|Coastal waters are close to us|
|What is eutrofication?|
|Sources of over-fertilization|
|How the open masses of water are effected|
|How shallow bays are effected|
|What can we do?|