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Seaweed holds massive importance in today's world. Since seaweeds are fast-growing algae, they utilise energy from sunlight and take up nutrients and carbon dioxide from the seawater. Scientists suggest seaweed could help fight climate change and offset carbon emissions. Therefore, not only is seaweed used widely as a source of food however after a lot of research and design, but it is also
known that seaweeds are important to make marine bio-resources and is widely used in many fields and industries.
The different and new uses of seaweeds can be found in fertilisers, feed, biomass
and fuels, cosmetics, integrated aquaculture, and water waste management.
Fertilisers
Like all brown seaweeds, Ascophyllum contains alginate, a carbohydrate composed of long chains. When calcium is added to alginate, it forms strong gels. By composting the dried, powdered Ascophyllum under controlled conditions for 11-12 days, the alginate chains are broken into smaller chains and these chains still form gels with calcium, but they are weaker. The composted product is a dark brown, granular material containing 20-25 percent water and it can be easily stored and used in this form. Steep slopes are difficult to cultivate with conventional equipment and are likely to suffer soil loss by runoff. Spraying such slopes with composted Ascophyllum, clay, fertilizer, seed, mulch, and water has given good results, even on bare rock. Plants quickly grow and topsoil forms after a few years. The spray is thixotropic, i.e. it is fluid when a force is applied to spread it, but it sets to a weak gel when standing for a time and sticks to the sloping surface. It holds any soil in place and retains enough moisture to allow the seeds to germinate. Composted Ascophyllum has been used after the construction of roads in a number of countries, and has found other uses as well (Blunden, 1991)
Biomass and Fuels
It is believed that the production of seaweeds can help produce methane gas and
thus can be converted into a type of biofuel that will also be environmental friendly since there would be lesser methane emissions released in the atmosphere instead will be recycled for a more better biofuel
Cosmetics
"Extracts of seaweed" is often found on the list of ingredients on cosmetic packages, particularly in face, hand and body creams or lotions. This usually refers to the use of alginate or carrageenan in the product, and their uses in cosmetics have already been discussed in earlier sections. More information on the use of these two hydrocolloids, as well as agar, can be found in the reference suggested below for further reading. The seaweed pastes are made by freeze grinding
or crushing. The seaweed is washed, cleaned, and then frozen in slabs. The slabs are either pressed against a grinding wheel or crushed, sometimes with additional freezing with liquid nitrogen that makes the frozen material more brittle and easier to grind or crush. The result is a fine green paste of seaweed. Milled seaweed, packed in sachets, is sold as an additive to bath water, sometimes with essential oils added. Bath salts with seaweed meal are also sold.
Thalassotherapy has come into fashion in recent years, especially in France. Mineral-rich seawater is used in a range of therapies, including hydrotherapy, massage and a variety of marine mud and algae treatments. Integrated Aquaculture Seaweeds can be cultivated by the raw material of the agar industry.
Previously, seaweeds were introduced into the aquaculture industry to make it easier. This concept of polyculture, or integrated aquaculture to use the more recent terminology, has since been utilised in many situations where the effluent from the aquaculture of one species, potentially threatening environmental damage, can be utilised by another species to its advantage, with a reduction in
pollution. Various strategies have been tried.
Seaweed cultivation around the outside of fish cages has led to significantly better growth of seaweed but was only partly successful in removing the large
amount of nutrients coming from the fish cages.
Waste Management
The two main areas where seaweeds have the potential for use in wastewater
treatment. The first is the treatment of sewage and some agricultural wastes to reduce the total nitrogen- and phosphorus-containing compounds before release of these treated waters into rivers or oceans. The second is for the removal of toxic metals from industrial wastewater. Seaweeds can be used to reduce the nitrogen and phosphorus content of effluents from sewage treatments. Many seaweeds have a preference to take up ammonium as the form of nitrogen for their growth and ammonium is the prevalent form of nitrogen in most domestic and agricultural wastewater. Another important feature of many seaweeds is their ability to take up more phosphorus than they require for maximum growth. It would be preferable to use seaweeds that have some commercial value, but
these do not necessarily have the ability to withstand the conditions encountered in the processing of the wastewater. There is a need for the seaweed to be able to tolerate a wide variation in salinity because of the dilution of salinity by the sewage or wastewater. Intertidal and estuarine species are the most tolerant, especially green seaweeds such as species of Enteromorpha and Monostroma. Of
the red and brown seaweeds that are of interest because of their commercial value, tropical or subtropical forms have been successfully used, while cold-temperate species are usually too sensitive to change seasons and may fail to grow (and remove nutrients) in the winter months.
While many investigations have demonstrated the suitability of seaweeds for wastewater treatments, their use on a large scale is yet to be implemented, although this may change with the increasing realisation of the need to protect marine environments.
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