 |
|
We should try to avoid cultivating only one type of crop and after harvesting
leaving the land fallow during the autumn and winter. If for example, another
type crop was sown during the autumn, the straw from it can for example
be used to produce methane gas, it can even be mixed with liquid
manure to reduce nitrogen seepage from the soil.
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
It is important that all households, industries
and farms are connected to some form sewage treatment facility. Unfortunately
this is not the case in some of the countries surrounding Sweden. In Sweden
for example, about 98% of the households are connected to a sewage plant
that uses chemical felling as part of the treatment process. This is not
the case amongst some states around the Baltic. In certain former eastern
states, untreated sewage is discharged directly into the rivers that flow
into the Baltic. It is important that more affluent states contribute both
economically and technically to reduce these pressures on the sea.
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!
 |
Page
24 of 28 |
 |
|
