Management of ship-generated food waste and sewage on the Baltic Sea: A review

The combination of increased maritime transportation and the sensitivity of the Baltic Sea makes it necessary to establish efficient, eco-friendly and profitable ship-generated waste management strategies. This study aims to identify best management practices for ship-generated nutrient-rich organic wastes, i.e. food waste and sewage, on the Baltic Sea. Ship-generated waste quantities and characteristics, maritime waste regulations, and disposal methods are reviewed and discussed according to the available literature for the Ports of Helsinki, Stockholm, Tallinn and Copenhagen Malmö, which are the most important and busiest ports on the Baltic Sea. Sorting onboard and separation of food waste from other waste sources such as sewage and grey water is a suitable solution that facilitates further treatment. However, this procedure demands special facilities and sufficient storage space. Aforementioned food waste can be delivered to port reception facilities (PRFs) and used to produce biogas at land. However, currently only food waste from ships operating in the EU may be used as input for biogas production, not international food waste. Grinding of food waste and discharge into the sea is still common practice. In addition, shipping companies can choose buffet type restaurants in order to reduce food waste generation. Grey wastewater is generally discharged into the sea, whereas sewage needs to be treated on board before discharge or delivered to PRFs for treatment. New MARPOL regulations for passenger ships on the Baltic Sea require advanced treatment of pollutant nutrients, nitrogen and phosphorus, before sewage discharge in order to combat eutrophication of this sensitive area.