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Algae farms are places where algae farmers grow algae for commercial use. Algae farming is also known as algaculture. Algae farms grow a wide variety of algal species. Microalgae are commonly grown commercially. Microalgae are sometimes also known as planktonic algae and phytoplankton. But even the larger algal species, known as macroalgae and including seaweed, also have commercial uses. However, the size and sensitive growing conditions required for macroalgae make them a challenging species to grow in an artificially controlled environment.
The most common commercial uses of algae grown on algae farms are:
1. Food coloring
4. Pollution control agents in water bodies
Algae farmers also grow a few varieties of algae for human consumption and nutritional supplements.
Monoculture refers to algae farms that grow only one type of algae. Algae farmers practicing monoculture take great care to ensure that their algae harvest is pure. It is relatively easy for their algae farms to get contaminated with other algal species. These new algae could dominate the original species, completely wiping them out. Algae obtained through monoculture are valuable for researchers in medicine and fuel.
Farms that grow and harvest a mixture of algal species mainly supply those as food for other aquatic organisms such as larval mollusks. Algae provide a cheap way for aquaculture farmers to feed their stocks.
Algae grow in areas where food crops cannot grow. Algae can also grow in wastewater, where conventional food crops cannot grow. Algae can thrive almost anywhere where carbon dioxide, sunlight, water, and minerals are abundant. In places that do not receive enough sunlight, algae sometimes take in organic substances like plant matter as food.
On algae farms, a delicate and precise balance between light, water, minerals, and carbon dioxide provides a thriving condition for algae. The correct combination of these elements provides energy to the algae and contributes to their healthy growth.
Each species of algae thrives at a different temperature range. Farmers go through great pains to ensure that the water is at the correct temperature for the algae to grow. However, the average optimum temperature range for healthy algal growth is between 25 and 35oC.
Some species of marine phytoplankton are extremely sensitive to changes in water salinity levels. However, most species of marine algae are incredibly tolerant to changes in salinity and mostly thrive in waters with salinity levels slightly lower than their native habitats.
Algae, especially microalgae, are typically present in a diluted state in water. Therefore, farmers use only the best and proven methods to harvest algae. They usually employ one of the following methods:
Only large algae farms usually use this method since it is an expensive way of harvesting algae. Here, farmers use the powdered shells of crustaceans to interrupt the carbon dioxide supply to the algae. With their carbon dioxide supply cut off, the algae float to the surface of the water. Farmers then skim the algae from the water surface.
The centrifugation method is similar to the way scientists use centrifuges in laboratories. In this method, farmers place the water containing the algae in a centrifuge. The rapid spinning of the centrifuge separates the water and the algae. Farmers recover the algae and dispose of the water. This method of harvesting algae is a medium-cost one and is what farmers usually use.
This is the simplest method of harvesting algae. Farmers simply sift the algae out of the water using a fine mesh.
4. Membrane separation
Farmers use this method to harvest microalgae. Membrane separation occurs in the laboratory. It is a form of filtration. The equipment for this method consists of a funnel attached to a vacuum flask. A filter is placed over the funnel. A trained person will pour the contents onto the filter. The vacuum allows the contents to dry quickly on the filter. After a while, only the algae will be left behind on the filter, and all the water will be sucked into the funnel by the vacuum.
Farmers use sedimentation in conjunction with other methods since sedimentation alone is not enough to recover all of the algae. Sedimentation is also known as gravity settling. Farmers employ this method in the initial phase of separating algae from the water. They first agitate or disturb the water. After agitation, they allow some amount of time to pass for the algae to clump together and settle to the bottom. They then retrieve the algal clumps from the bottom of the water.
Algae serves so many purposes. It grows ten times faster than land plants. They use less than a tenth of land to produce an equivalent amount of biomass as that of plants. Algae can grow in non-productive areas, ensuring that they don’t compete with other plants for land. Algae do not require fresh water to thrive. Because of this, we can fertilize it much more efficiently as compared to land crops. We can save the enormous amounts of water associated with modern, land-based agriculture.
Due to its rapid growth, algae can be an important source of biofuel. Biofuel from algae is environmentally and economically viable. Many climate scientists believe that algae could be the answer to our fuel problems, providing a valuable source of carbon-neutral fuel. Apart from fuel, algae also offer a source of high protein for human consumption.
In 2018, Charles Greene, a climate scientist, formed a research team to look into the commercial viability of biofuel from algae. He and his team found that growing algae just to produce biofuels would be expensive. But they also found that the algal biomass leftover after taking what’s needed to produce biofuels is highly nutritional. We could use this residual algal biomass in aquafeeds for salmon and shrimp. We could also use it as animal feed for chickens and swine.
The research team found that to provide biofuel for the entire world, we would have to grow algae in an area only slightly less than three times the size of Texas. Using just this much land, we could provide the world with protein ten times the amount of soy produced all over the world.
Imagine the vast areas of forests, ecosystems, and natural habitats we could save just by increasing our direct and indirect consumption of algae. Clearing rainforests in Brazil and Indonesia to grow soy and palm would stop. By 2050, the Earth will host around 9.5-10 billion people. With algae, we now have a way of feeding all those people. Algae have provided the world with a way of combating malnutrition in developing countries.
Algae farms do not introduce new carbon dioxide into the atmosphere. Algae farms have huge and positive land-use implications. With algae farms, we can have food security and maintain biodiversity. However, right now, the world is producing algae on a tiny scale. We need to grow algae on a large scale appropriate for commodity markets.