Ships still discharging hundreds of tons of sewage into Baltic Sea

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With the lavatory waste released from ships, much more eutropic nutrients enter the Baltic Sea than from the entire city of Helsinki.
      Some treated lavatory waste, the so-called black water, still ends up in the Baltic Sea, even though since the fuss around the Tallink cruise line in November, more ships now pump their effluent into sewer systems at harbours.
     
The sewage treatment systems on ships are rarely as effective as the treatment facilities on shore.
      Cargo vessels still release both their sewage and washing water into the sea after only light processing. Some of the washing water, the so-called grey water, still ends up in the sea totally untreated.
      According to HELCOM, the Baltic Marine Environment Protection Commission, at any given moment there are around 1,800 vessels sailing the Baltic Sea carrying a minimum of 200,000 passengers and crew.
      It is estimated that half of the sewage from these vessels ends up in the Baltic Sea, enriching its waters with 440 tons of nitrogen and 100 tons of phosphorus each year.
      Limnologist Seppo Knuutila from the City of Helsinki Environment Centre confirms that the combined phosphorus emissions of the vessels are fourfold compared to those from the entire Helsinki area.
      The measure of nitrogen, in turn, equals the amount processed by the Viikinmäki waste water treatment facility, which processes the effluent from 750,000 people.
     
Compared with the total nutrient strain on the Baltic Sea - 6,000 tons of phosphorus and 120,000 tons of nitrogen per year - the ships' impact is minute.
      Yet, as individual sources of nutrients the ships are significant, particularly in the summer, when their effluents directly fuel the growth of algae.
      "With its treated effluents, a single 2,000-passenger cruise vessel releases the same amount of phosphorus into the sea in a year as does the city of Kotka on the southern coast of Finland", Knuutila compares.
      He also issues the reminder that from the environmental protection point of view the treatment of effluents on ships is inconsequential, as it does not remove the nutrients responsible for eutrophication.
     
Last November, Helsingin Sanomat caused a stir by reporting on the Estonian Tallink cruise line's vessels having released their wastes into the Gulf of Finland after an onboard biological treatment.
      The practice was, and still is, legal, but from the moral point of view it was considered questionable because of its impact on eutrophication.
      Because of the fuss and boycott threats from passengers, Tallink has since changed its practice, as has Superfast Ferries, which was purchased by Tallink in the spring.
     
Cargo ships still tend to release their waste water into the sea after only a light physiochemical treatment.
      The shipping companies complain that cargo ports often lack facilities to pump the ships' effluents into any onshore sewage systems.


Previously in HS International Edition:
  Superfast Ferries prepares to dispose of wastewater into sewage system on land (18.11.2005)
  Tallink vessel pumps wastewater into City of Helsinki´s sewer system (16.11.2005)
  Tallink ships still discharging sewage into Baltic Sea (14.11.2005)

Links:
  HELCOM

Helsingin Sanomat