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Written by Sara Bottome

At the moment, as much as 65% of the estuaries and coastal waters in the U.S. have been affected by moderate to severe diminishing of the diversity and health of their ecosystems. The main reason? A process known as eutrophication, where excessive amounts of nutrients from runoff containing animal waste, nitrogen, and phosphorus from fertilizers are deposited into lakes and coastal waters. These dense nutrients lead to the growth of plants and massive algal blooms, which are eventually decomposed by bacteria, depleting the waterways of oxygen and killing animal life. Currently, most algal blooms are nothing but destructive. Many researchers and industries have become interested in the potential of algae as a useful alternative to common contributors of pollution. This article will discuss three of these developing (and some already implemented) uses for algae.

Can better plastics be made from algae?

Most people use typical plastic items, such as plastic bags and wrappers, for mere minutes, perhaps an hour. But what happens to these fossil-based plastics once they litter the environment? Many plastics contain additives that make them more flexible and durable, and as a consequence, they are harder to break down. Plastics are estimated to remain in the environment for hundreds of years, even thousands, and their production increases every year. Plastics eventually degrade into microplastics, which have a multitude of negative effects on water, air, and food (mostly seafood) quality, and the health of marine life. While certain efforts exist, such as recycling and decreased manufacturing, to fix the issue of plastic pollution, they are not enough, and replacing current plastics with biodegradable bio-based plastics would help eradicate the issue of plastic pollution in the first place.

Bioplastics currently make up only 1% of the annual plastic production worldwide. Why haven’t they become more mainstream? Current bioplastics are produced mainly from crops such as corn and potatoes, which compete with food sources and use up large amounts of land and resources, making their production unsustainable in the long run. Commercialization has been difficult due to economic issues with large-scale production and competition from cheaper fossil-based plastics. 

Algae-based bioplastics pose a promising solution; algae is a potentially better biomass source for bioplastic production since it is not a food source, has the ability to grow on waste resources, and can achieve high lipid accumulation. The current challenge is the development of more efficient and sustainable bioplastic production technologies for algae. Many current technologies are still lab-based and are difficult to commercialize due to high costs and the use of additives. One promising approach which is being explored due to lower costs is a biorefinery concept in which the by-products of high value chemical production from microalgae are used to produce bioplastic.         

Can better biofuels be made from algae?

The main contributors to global CO2 emissions and the increasingly devastating effects of climate change are fossil fuels. It is clear that their use is extremely unsustainable and harmful for our planet, and yet, the world still struggles to move away from their use. Compared to many forms of renewable energy, fossil fuels are cheap, reliable, and fully integrated into the technologies and way of life of millions of people. These advantages do not outweigh the negative consequences of their use, but they do explain part of why it has been so difficult to make a transition to renewable, clean energy sources. 

This is where biofuels come in. Biofuels are admittedly not as beneficial for the environment as other forms of renewable energy such as geothermal and wind energy, but they are more renewable and sustainable than fossil fuels. Most importantly, they are easier and faster to substitute for fossil fuels than other forms of renewable energy due to the already-existing infrastructure that could be applied to their transportation and use. Biofuels could therefore act as important replacements for fossil fuels, until the full transition can be made to the cleanest energy sources. There are issues with biofuel though; same as with bioplastics, many biofuels are currently made from crops that could also be used as food sources and thereby expand land use. Even cellulosic biofuels, which are made from non-food crops and waste biomass, can result in increased crop prices, encouraging the development of untouched land, harming its biodiversity and releasing even more greenhouse gases. Not to mention, the production of biofuels is more expensive than the production of fossil fuels, often requiring subsidies and other market interventions to compete economically with fossil fuels.

Once again, algae presents a possible solution. The main advantage of using algae for biofuels is its greater biomass productivity and oil production in comparison to other sources of biomass, which renders it more competitive against diesel and fossil fuels. Furthermore, algae can be grown almost anywhere, including on waste resources and at locations where the algae can absorb the nutrients from fertilizers near farms, thereby preventing the spread of the fertilizers to regions where the algae could cause more harm. Current research on the production of biofuels from algae focuses on reducing production costs and commercialization.   

Algae: the final step in wastewater treatment

Many of the substances that pollute the environment are produced as a result of industrial, agricultural, and domestic uses of water. Currently, most treatments of these wastewaters consist of a primary and a secondary treatment which eliminate settled materials and oxidize any organic material present. However, the resulting “purified” water often still contains inorganic nitrogen, phosphorus, and some heavy metals, which are then released into the environment along with the “purified” water. These elements contribute to the eutrophication of aquatic environments and to the growth of destructive algal blooms.

Already implemented in many wastewater treatment centers, the controlled use of algae as a tertiary treatment of wastewater eliminates the presence of the destructive elements, while also providing algal biomass for other purposes. Algae grows from the nutrients provided by nitrogen and phosphorus, and is even able to remove heavy metals and certain toxic organic compounds from the wastewater, which is then safe to release.

The possible uses of algae do not end with the production of bioplastics and biofuel, or with its use in wastewater treatment. Algae can be used in everything from animal feed and vegetable oil to fertilizers. Only time (and research) will tell what else it can do.