Report No FR0125
REVIEW OF MARINE DISCHARGE PRACTICES IN EUROPEAN
To provide the members of the FWR with information on the treatment and disposal of
municipal sewage in coastal areas of countries in northern Europe.
The European Commission has published (COM (89) 518 final) a proposal for a directive
which stipulates minimum levels of treatment for sewage prior to its discharge into inland
watercourses, estuaries and coastal waters. The Commission has also published (COM (88)
708 final) a proposal concerning the protection of fresh, coastal and marine waters
against pollution caused by nitrates from diffuse sources. The Third International
Conference on the Protection of the North Sea agreed various common actions aimed at
reducing inputs of nutrients to the sea, including the loads arising from sewage. The
investment implications of these measures are substantial and it is therefore of interest
to review the situation elsewhere in Europe and particularly in countries surrounding the
- The present status of sewage treatment in the countries reviewed reflects previous
policies and levels of investment as well as regional patterns of population density and
industrial development. Considerable investment has been made in most countries since 1970
to improve sewerage, sewage treatment and disposal facilities. It is recognised in
Belgium, France and Ireland that substantial additional capital investment is required to
extend the municipal sewerage systems and to ensure that adequate conventional treatment
facilities are available for the resulting flows.
- National standards for the control of discharges have been adopted in most countries,
either as limit values (FRG, Belgium, Denmark, France, Netherlands, Ireland and Norway) or
values typically applied on a case-by-case assessment (Sweden). Limits for some
determinands vary in several countries depending on the location of the discharge
(Belgium, Ireland, Norway, Sweden) and/or its size (Denmark, FRG, Norway, Netherlands,
Sweden). In France, the departmental administration selects the level of treatment (and
associated limit values) to be applied to a particular discharge according to local
- Discharges to marine waters account for more than half the municipal sewage and
wastewater in Ireland (84% of sewered polluting load), Norway (75%) and Denmark (62%), and
for only 43% in Sweden, 27% in the UK and 21% in the Netherlands. No distinction is made
in the FRG between discharges to inland or tidal waters.
- Secondary biological sewage treatment is widely used throughout northern Europe. The
activated sludge process and biological filtration are mainly applied, although a variety
of treatment types are used in the Netherlands and chemical precipitation is also
practised in Scandinavia and lagooning of sewage effluent in parts of France. Sewage is
disinfected only in a few situations for relatively small flows.
- Concern about eutrophication and its effects in marine waters has led to the control of
nutrients from sewage and wastewaters. Sweden, for example, has applied chemical
precipitation for the removal of phosphorus to the majority of urban sewage. More
stringent standards recently adopted in Belgium, Denmark, FRG, Netherlands, Norway and
Sweden will require additional treatment to reduce concentrations of phosphorus and
nitrogen in sewage effluents (in most cases by 1995). Five countries (Denmark, FRG,
Netherlands, Norway and Sweden) have action plans expected to reduce total annual inputs
of phosphorus and nitrogen from municipal effluents by 45 000 and 242 000 tonnes,
- The major European rivers (Rhine, Elbe, Weser and Scheldt) are principal sources of
polluting loads entering the North Sea and concern about transport of pollutants from
upstream countries is reflected in the pollution control policies of countries further
downstream. Concerted action is being taken to improve effluents discharged to the River
Rhine and similar action is contemplated in the case of the other rivers.
V RESUME OF CONTENT
- Note should be taken that the provision of sewerage and sewage treatment facilities in
each country reviewed varies considerably. Particular attention should be given to the
concern about nutrient loads discharged from municipal sewage and wastewaters shown in a
number of the countries around the North Sea. The extent to which treatment has been
adopted or is planned to reduce nutrient concentrations in municipal effluents discharged
to coastal waters should be recognised, together with the levels of investment involved in
achieving the discharge standards already set. The review should be read in conjunction
with proposals for new EC legislation concerning municipal wastewater treatment and
international policy decisions about environmental protection of the North Sea.
- Data quoted in this report were taken preferably from returns to questionnaires, from
Sobemap (1990) and Waterfacts (1988 and 1989). As the data vary sometimes significantly
from one source to the other, the data source is indicated where appropriate.
An interim report (FR 0064) published in January 1990 was based on readily available
published literature on sewage treatment in coastal areas of the nine countries reviewed.
Further information obtained from questionnaire enquiries and personal contacts has been
incorporated in this report which concentrates on discharge standards and treatment
practices. The earlier report should be consulted for information on legislation and
Copies of the report are available from FWR, price £35.00, less 20% to FWR Members.