Coastal Seaweed Solutions
de Bruijn, L.
de Vries, S. (mentor)
Miedema, S.A. (mentor)
Civil Engineering and Geosciences
In recent years, strange phenomena occurred in the Caribbean, Gulf of Mexico and West Africa: a massive tide of sargassum, brown algae, washed ashore causing considerable damage to the local economy and environment. The sargassum mostly consists of Sargassum Natans and Sargassum Fluitans. Old studies concluded that the sargassum came from the Sargasso Sea, however the most recent massive tide of sargassum (named as golden tide) came from an area north of the Amazon river delta. Texas A&M University of Galveston and the University of Florida developed detection systems in cooperation with NASAs satellite images. With the detection system it is possible to track, trace and make forecasts of sargassum landings. Hereby it is possible to act a few days before the sargassum washes ashore, instead of reacting when it landed on the beach already. Most of the problems occur when the massive influxes of sargassum are washed ashore. Currently, the most used harvesting methods on the beach are by use of rakes and wheelbarrows or by using mechanical equipment like a cane loaders and front-end loaders. The beach cleaning methods causes beach erosion and endangers local wildlife. Therefore, harvesting methods at sea are under development. Sargassum is an organic material and can be an useful source for processing. The most used processing methods of sargassum are burying at the beach or using it as a fertiliser. One of the challenges in processing sargassum is working with the unpredictable appearing character of sargassum. The known detection methods have been critically analysed and the most favourable method is developed by Texas A&M University Galveston. This system is applicable on other areas as well and it makes forecasts of sargassum landings. The harvesting methods have also been critically analysed and it can be concluded that the most recommended harvesting method has to be done at sea in combination with a floating barrier. Most of the problems are avoided in this manner. For processing multiple opportunities have been pointed out. Biofuel and bioplastics are having large potential. For the mean time using sargassum as a fertiliser is a su cient solution. The uneven appearances can be solved by drying the sargassum. Finally, an implementation plan is developed for Quintana Roo to overcome the sargassum problems. It is a step-by-step approach which can be conducted by a party who is willing to take the lead. In this approach the detection system of Texas can be used and new harvesting methods have to be developed. For processing, dry facilities have to be built in order to solve the uneven appearances.
« From the multi criteria analysis can be concluded that a harvesting boat with a barrier has the highest potential. This will therefore be the recommended method. High potential lies within barges with an extra system for harvesting. The characteristics of the equipment and the exact
processing method depends per case. In section 8.3 an elaboration is given for a specic golden tide project.
When a barrier cannot be applied, harvesting boats at the shore face will give the best results according to the MCA. But one has to keep in mind that this method especially scores good on environmental related aspects and that the exact eciency still has to be researched. In theory a skimmer with a barrier will also lead to good results, but equal to the other methods: workability and efficiency have to be researched in a later stage of development. Beach harvesting methods result in rather low scores and will therefore only be favoured as an additional back-up plan or when none of the other methods for some reason can be applied. »