The barriers installed on the Sarno river |
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THE INTUITION OF AN ITALIAN ENGINEER Ten years ago Fabio Dalmonte, an Italian engineer, was about to obtain a master’ s degree in waste management in Scotland and was engaged on some projects on the rivers in Indonesia. At the basis of his path and his intuitions, there has always
been the awareness that about 80 % of the plastics entering the oceans come from rivers. The fastest solution to reduce plastic waste should be, therefore, to stop plastic in river basins before uncontrolled dispersion can start into the seas and oceans. A vision that would have further confirmation from another illustrious quote by Coehlo:“ The waters of a river adapt themselves to whatever route proves possible, but never forget the objective: the sea.” Within this context and driven by valid scientific
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reasons, Dalmonte began to develop the“ Blue Barriers”, engineered systems capable of effectively blocking plastic waste in rivers. In 2017 the first prototype was tested in the Lamone river, while the following year an industrial invention patent was filed which attracted the interest of another engineer, Mauro Nardocci, resulting in the foundation of a startup named Seads- Sea Defence Solutions.
A COMPLEX TASK Trapping plastic debris in moving water might seem an easy task. As a matter of fact it’ s surprisingly complex. Rivers are challenging environments, and plastic behaves in a particular way in them. Seads is not the only company looking for solutions to rid rivers of plastic waste, so that there are numerous contacts with other players such as, for example, The Ocean Cleanup. The problem, in fact, has taken on such a critical and dangerous dimension that it can no longer be solved through competitive approaches, but it is necessary to create a collaborative network of stakeholders. Within this network, Seads’ Blue Barriers stand out for their simple design that guarantees a general ease of construction and assembly. Each 20-meter section is composed of floating modules of recyclable materials: an internal core of steel cables inside a floating polyethylene structure. The barriers sink up to 90 cm below the water surface, while waste plastics usually occupy 50 cm in the water column. The barriers always maintain a perpendicular position, as a result maximising their harvesting capacity. Finally, they are designed to have no impact on navigation or the river fauna. About 31,000 rivers, mostly small in size and near urban areas, are responsible for most of the
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plastics entering the oceans. Ideally, Blue Barriers will be produced locally, in the region where they will be installed, in order to minimise the impact of transport while creating jobs in the local communities. Seads has also been working in recent months on a new version of Bluer Barriers, even simpler to produce, geared to increasing its scalability potential.
BARRIERS CAPTURE ALMOST 100 % OF PLASTICS Strategically placed, Blue Barriers can trap almost 100 % of the plastics floating in the river. When the river course is sinuous, a single barrier( or at least a barrier of shorter length) placed downstream a meander can stop practically any solid object flowing. When the river course is straight, the barriers have to be staggered and placed in sufficient number to cover the entire width of the river. When conditions are particularly challenging, such as during storms or floods, the barriers are designed to open automatically in order to prevent damage or overflows. Thereafter, they can be manually pushed back into place. After successfully testing a Blue Barrier in the Tiber River in Rome, Seads installed its first system in 2022 in a bend of Aniene, a medium-sized river that reaches a maximum width of 27 meters. This barrier responded so effectively to the tests, that the project will soon be extended to allow the installation of a permanent barrier. Seads is planning to install the Blue Barriers in 30 rivers over the next five years. It is estimated that around 70,000 tonnes of waste will be harvested, CO2 emissions will be reduced by 14,000 tonnes and 7,000 birds and marine mammals will be rescued annually, while creating 280 direct and indirect jobs. Three projects are currently in the pipe-
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Italian technology plast / April 2025 |
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www. plastmagazine. it |
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