The nutrient load from food waste generated onboard ships in the Baltic Sea

• Food waste generated on ships can be discharged to the sea at a distance of 12 NM from the coast
• An estimation of the amounts of food waste generated on ships operating in the Baltic Sea has been made
• Nutrient load from ship-generated food waste and sewage has been compared

The combination of the sensitive characteristics of the Baltic Sea and the intense maritime traffic makes the marine environment vulnerable to anthropogenic influences. The theoretical scenario calculated in this study shows that the annually generated food waste onboard ships in traffic in the Baltic Sea contains about 182 tonnes of nitrogen and 34 tonnes of phosphorus. Today, all food waste generated onboard can be legally discharged into the marine environment at a distance of 12 NM from the nearest land. The annual load of nitrogen contained in the food waste corresponds to 52% of load of nitrogen from the ship-generated sewage. Future regulations for sewage discharge in the Baltic Sea will require significant reduction of total nitrogen and phosphorus released. The contribution of nutrients from food waste compared to sewage will therefore be relatively larger in the future, if food waste still can be legally discharged.