The City of Helsinki Baltic Sea challenge and City of Helsinki construction services Stara are working together with Clewat Oy over the summer by testing a new type of Cleansweep trash collecting vessel 23 June−3 July and 21−31 July 2020. The tests are conducted to determine how well the vessel performs in controlling the amount of rubbish in the sea.


The City of Helsinki Baltic Sea challenge and City of Helsinki construction services Stara are working together with Clewat Oy over the summer by testing a new type of Cleansweep trash collecting vessel 23 June−3 July and 21−31 July 2020. The tests are conducted to determine how well the vessel performs in controlling the amount of rubbish in the sea.

An increasing amount of garbage is continuously collecting in the sea. Last year, Stara collected roughly 80 cubic metres of rubbish from the coast of Helsinki with its Lippo vessel. Rubbish is mostly generated by people eating, drinking and smoking. Rubbish ends up in the sea via stormwater, rivers and winds. More than 70 per cent of the trash that ends up in the sea is plastic, which decomposes slowly and causes harm to people and animals.

Stara is in charge of cleaning waters in the sea areas and waste management in the archipelago. In the summer, Stara will be testing the performance and operation of the Cleansweep vessel and comparing it to the Lippo vessel for a period of one month. The objective is to develop and streamline trash collection so that small plastic particles could also be collected.

The operation of the Cleansweep vessel, developed by Clewat Oy, is based on the utilisation of water flow. The vessel uses beams in the front to collect plastic trash to the mouth of the vessel, where the flow of water is controlled so that various types of debris end up on the vessel’s conveyor, where it is sorted into tanks. The Cleansweep vessel is able to collect plastic pieces as small as half a millimetre in diameter from the water.

New innovations through agile trials to control the amount of rubbish in the sea

The Baltic Sea challenge, a City of Helsinki coordination programme for voluntary protective measures of the Baltic Sea, started agile trials this spring to find innovative solutions to control littering in the sea areas of Helsinki. Clewat Oy was selected to join the trials to determine the quantity and quality of the plastic debris collected by the Cleansweep vessel especially in sea areas that are challenging to keep clean. Over the summer, the Cleansweep vessel will be operating in Kalasatama, Vanhankaupunginlahti and Töölönlahti. In addition to Clewat Oy, Bloft Design Lab, Green House Effect Oy and Biosatama Oy were also selected for the agile trials.

The Baltic Sea challenge is a Baltic Sea protection effort coordinated by the Cities of Helsinki and Turku, including a shared Baltic Sea Action Plan of the cities and the Baltic Sea challenge partnership network. The Baltic Sea challenge network includes more than 300 organisations, and it welcomes all organisations interested in protecting the Baltic Sea.

Image: Clewat Oy.