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Sheet 9: Other ways of using Sargassum

AFAI HUE 12 DEC 2022

A sea of opportunity

Sargassum continues to proliferate and invade Caribbean, West African and North American coasts every year, with an average 3 million tons more Sargassum at sea each year than the previous year.  Unlike some natural resources that are dwindling, such as wood, the necessity to exploit the seaweed is pressing, since the resource is increasing and becoming increasingly toxic. However, the random aspect of the strandings continues to hinder development and financing plans that do require a certain stability. Citizens, associations, local authorities, governments and entrepreneurs are all organising themselves and building projects on their own scale.


Sargassum paste and its uses

In Saint Barthélémy, the Sargasse Project was born from the desire of one man, Pierre Antoine Guibout, to use this harmful raw material and convert it into useful and ecological biomaterial, for a circular economy.

Faced with the increasing number of strandings, Pierre-Antoine began testing seaweed samples in his kitchen, with the initial idea of reducing them to a powder to be used in shoe polish. The idea was not very conclusive and was abandoned in favour of the manufacture of a paste based on Sargassum, made according to a precise procedure: harvesting, drying, grinding and alloying with the alginate and cellulose contained in the seaweed. A future base for various possible uses: traditional paper, cardboard paper that absorbs heavy metals, anti-bacterial cardboard paper, food packaging, construction materials (the compressed pulp can withstand 10 bars of pressure, a capacity similar to that of wood) and even electronic payment paper (insofar as the metal ions make the paper forgery-proof). This paper will not be manufactured by the Sargasso Project but by the numerous industrialists interested. This is a promising prospect, especially yield wise: 500 kg of fresh seaweed can be used to obtain 250 kg of dried seaweed and the same amount of pulp. 100% biosourced and environmentally friendly, Sargassum pulp is becoming increasingly attractive. Two dents in the picture remain however- the still difficult management of lead captured by the algae, since if heavy metals can be degraded, lead on the contrary is an exception to the rule except from being made inert. Furthermore, the unevenness of the strandings hinders the production and development stages of the project at industrial level.


In Mexico, others have had the idea of making paper from Sargassum, but in a more artisanal way. Victoria Morfin, a young woman of 18, decided to take up the idea of recycling Sargassum with the aim of respecting the environment. The first tests carried out with the help of her mother took time, Victoria trained herself online, but they were finally conclusive and in one year, Sarganico, a family business, has used nearly 12 tons of Sargassum. The collection is well thought out and reasoned, since out of these 12 tons of Sargassum collected in 2018, 10 tons of sand were extracted and returned to the beach; the objective being to limit the impact of the collection on soil erosion as much as possible. Sarganico paper has become very popular and the local printing company Grupo Regio, has already joined in the development and marketing of this innovative material.

papier sargasse

Environmentally friendly plastic

The figures speak for themselves: every year, nearly 8.3 billion tons of plastic are produced, 500 kilos per minute end up in the oceans, and the most inaccessible and therefore most protected coastlines, are also affected by this pollution. However, we note that investment in petrochemical and plastic industries is increasing year by year, along with production quantities.

Since 2011, a team has been working to find solutions and produce bioplastic, i.e. plastic made from biomass and 100% natural. Algopack, a company based in Saint Malo, Brittany, led by a former engineer from the plastics industry, was founded spurred by the catastrophic observation of massive pollution. The idea is to develop materials having a positive impact on the environment, as Brittany has long been faced with invasions of green algae and is one of the pioneer regions in their management. Since 2011 and the arrival in quantity of Sargassum seaweed in the Caribbean, Algopack have been working on its valorisation. Sargassum is a more fibrous biomass than green algae and its water content is much lower (around 90 to 98% less). Also, the polysaccharides (sugars) contained in the seaweed ensure better stability in the recovery process. 

2018 marked the year when the scientific formula was found- Sargassum can be used to make bioplastics. Today the company is developing a pilot chain ranging from population protection with the avoidance of strandings (mainly booms installation), to the recovery of the material- including collection, pre-treatment, and the transformation of the algae into bioplastics. 


In Mexico, scientists* from the Universidad Autonóma Metropolitana in Azcapotzalco (Mexico State), whose research is aimed at obtaining a natural, compostable polymer (or plastic) based on starch, cellulose and alginate extracted from Sargassum, are obtaining very satisfactory results. This natural polymer shows similar capabilities to conventional plastic, with the advantage that it does not pollute and degrades naturally and even faster than cardboard. 

The manufacturing techniques for these sargassum-based bioplastics are very advanced (although still at R & D stage) and consist of two phases. The first consists of extracting sodium alginates from the Sargassum by infrared, the second involves the agglomeration of cellulose and starch. A whole series of processes is applied, i.e. washing collected seaweed, drying, mixing, acid extractions, filtrations, solidification phases, and sodium ion additions. 

These bioplastics have the same applications as conventional plastics, they can be used for food packaging (heavy metals will have been neutralized), as materials for the automotive industry, furniture etc., with the enormous difference that they are Carbon neutral throughout their life cycle. 

Sargassum plates that were made for the experiments for example, show to have the same lifespan as conventional plastic plates, same solidity, more flexibility and a similar look. 

The degradation characteristics are not comparable as it is noted that a Sargassum plate is subject to the action of micro-organisms which degrade it in six weeks, while cardboard plates take between 2 and 5 months to degrade, while conventional plastic plates require between 100 and 1000 years. 

*García Martínez Katia and Sanchez Fuentez Cinthia Erika, Environmental Systems Engineering Department; Salazar Cano Juan Ramón, Biophysics Department; Gómora Herrera Diana Rosa, Mexican Petroleum Institute; Sanata Cruz Alejandra, Department of Basic Sciences.


Sargassum molecules to heal?

As with seaweed recovery solutions, research is progressing into the use of Sargassum molecules for potential treatment of serious diseases, with fruitful starting results.

First leads concern the use of molecules for diseases such as lung cancer, HIV or Alzheimer’s. These projects are expensive, like the lung cancer or Alzheimer’s projects estimated to cost 750 000 euros.

The National Research Agency (ANR), together with the Collectivité de Martinique (CTM), Guadeloupe, Guyana and Brazil are gathering international funds to support the fight against Sargassum and for medical research.

In Portugal, some University of Porto Chemistry department researchers have observed that populations consuming a lot of plant-based foods have lower rates of cancer, identifying Sargassum as very promising, insofar as some of its molecules can act against cell death and certain damage to DNA. More research is needed.


Université Virtuelle de l’Environnement et du Développement Durable
Holdex Environnement
Les Echos

Interreg Caraïbe
Ocean Legacy
Université des Antilles
Revista Tendencias en dociencia e investigación en química
Universidad Autónoma Metropolitana de Azcapotzalco