Sassari Consortium: How Posidonia Oceanica Goes From Waste to Fertilizer and Fuel

In Sardinia, an all-Italian project will transform 20 tons of waste into new products every year.

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Posidonia screening

A marine plant, widespread throughout the Mediterranean, which is transformed from waste into new products, primarily fertilizer and green fuel. The Sassari Industrial Consortium, at the San Marco site in Alghero, in southern Sardinia, provides various services related to waste management and the circular economy. In recent months, it launched a major project for the recovery of beached Posidonia oceanica plants: a facility with the potential to treat 20 tons per year.

In general, the process follows these steps:

1. Collection and transfer
The Posidonia oceanica accumulated on the beaches is collected by municipal or environmental services and transported to the authorized areas managed by the consortium.

2. Storage and first separation
The material is left in storage areas where a natural dehydration process begins. This phase reduces the volume and facilitates the separation of the sand.

3. Sifting and recovery of sand
An important part of the treatment is the recovery of the sand trapped between the leaves and rhizomes: it is sifted and returned to the beach management cycle, reducing waste of natural material.

4. Biomass treatment
The plant fraction (the Posidonia itself) can be:

  • dried and stabilized
  • or sent to controlled composting processes.

At this point, the treatment reaches its final stage: transformation. And the Posidonia oceanica waste becomes:

  • Natural fertilizer or soil improver (rich in organic matter, excellent for organic farming).
  • Roofing or mulching material in gardens or agriculture.
  • Green fuel in some biomass plants, if treated properly.

During the manufacturing process, 60-70 percent of the sand present in the Posidonia oceanica is also recovered, which in turn is relocated to protect the coasts.
The benefit is twofold: on the one hand, it significantly reduces waste arriving from the sea and beaches; on the other, this waste, instead of ending up in some landfill, is used to create new products, which are also very beneficial to the environment.

The large amount of beached Posidonia oceanica we see on the coasts is largely a natural and seasonal phenomenon, also amplified by poor beach management.

Here are the main reasons for the huge amount of beached Posidonia oceanica waste:

1. Natural cycle of the Posidonia
Posidonia oceanica regularly sheds its older leaves, especially in autumn and winter. These leaves break off, are carried by the currents, and end up on beaches.

2. Storm surges and currents
During winter storms, the sea “tears” and moves large quantities of plant material from the ocean floor, accumulating it on the shore within hours or days.

3. Ecological function of the “banquettes”
These accumulations are not just waste: they form the so-called banquettes, which:

  • they protect the beach from erosion
  • they hold the sand
  • they host small organisms.

Cover photo from https://algherolive.it

The project is a candidate for the 2026 Non Sprecare Award, in the Companies section. To submit your projects for free, follow the instructions here.

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