Ships' sewage used to power trucks

Photo by Tom Fisk

One of Finland's busiest seaports is transforming wastewater discharged from freighters into biogas that can be used as fuel for lorries and trucks.

Southern Finland's port of Hamina-Kotka receives an average of 2,500 freighters a year. The wastewater management project was sparked by the Baltic Sea Action Group (BSAG), a Finland-based non-governmental organisation working to restore the ecological balance of the Baltic, one of the most polluted seas in the world.

The new scheme is part of the group's Responsible Shipping project, which seeks to reduce nutrient pollution from maritime traffic. Nutrient pollution refers to contamination caused by excessive discharge of nutrients which occurs when ships dump sewage into the sea.

"We can achieve our objective of a cleaner Baltic Sea, one ship, one port and one country at a time."

Elisa Mikkolainen, Baltic Sea Action Group

Passenger ships have been voluntarily unloading sewage at seaports for several years now, though the International Maritime Organization (IMO) has issued a ban on untreated sewage discharge from passenger ships, which came into force in 2021.

However, current laws allow freighters to discharge sewage directly into the sea. This can accelerate the growth of harmful algae, as well as oxygen depletion in the Baltic Sea.

"All discharge into the sea is unnecessary. This is why waste from ships should be discharged at the port and recovered. These new voluntary measures will lead the way for responsible operators both on land and at sea," BSAG said in a statement.

"We can achieve our objective of a cleaner Baltic Sea, one ship, one port and one country at a time. The nutrient load on the sea decreases every time wastewater is discharged at the port. We need extensive cooperation to succeed in our mission," added Elisa Mikkolainen, project director at BSAG.

The project currently involves various companies and organisations, with Kotka-based water supply and management company Kymen Vesi treating the wastewater discharged from freighters at the port. The firm also takes samples of the wastewater to obtain data on nutrient concentrations.

The treated wastewater is then processed and transformed into renewable energy at state-owned energy company Gasum's biogas plant, ready for use as vehicle fuel.