The Wonders of Microalgae
The sight of microalgae floating on seemingly unclean water, be it on an unkempt swimming pool or the edge of a lake or surface of wastewater, is sure to make one wince. But it will be surprising to discover that a lot of potentials abound in microalgae. If the microalga is removed from the water surface, oil can be extracted from it which is capable of running a car when the oil is converted to fuel. The microalga body mass (Biomass) can be source to different fuels- including cooking gas, healthy food supplements (proteins, carbohydrates, oils and vitamins) for human consumption, animal feeds additives, and a variety of inorganic and complex organic molecules. There are so many other good things that can be derived from Microalgae.
Algae are simple plants that can range from the microscopic (microalgae), to large seaweeds (macroalgae). Now, what are microalgae?
Microalgae are microscopic algae, typically found in freshwater and marine systems. They are unicellular (one-celled) species which exist individually, or in chains or groups. Depending on the species, their sizes can range from a few micrometers to a few hundreds of micrometers. Unlike higher plants, microalgae do not have roots, stems, or leaves. Microalgae, capable of performing photosynthesis, are important for life on earth; they produce approximately more than half of the atmospheric oxygen and use simultaneously the carbon dioxide to grow. In other words they produce about 60 percent of all the air we breathe.
Microalgae are the origin of the food chain, their presence on earth existed at the very early stages of earth. After billions of years of environmental changes, they did not become extinct and are still visible in our surroundings.
A Chemical Engineer and a researcher in the area of microalgae with Federal Polytechnic, Bida, Niger State, Engr. David Tsado, disclosed that microalgae can be grown using water resources such as brackish-, sea-, and wastewater unsuitable for cultivating agricultural crops. When using wastewater, such as municipal, animal and even some industrial runoff, they can help in its treatment and purification, while benefiting from using the nutrients present. Most microalgae grow through photosynthesis – by converting sunlight, CO2 and a few nutrients into material known as biomass. This is called “autotrophic” growth.
“Algae have been considered as potentials for next generation and renewable fuels. They have been regarded as one of the most promising candidate or source of biofuel production among the bio-feedstock currently being explored.
In recent times, emphasis has shifted to exploring algae as biocrude or for biofuel. Algae have been variously described as the ‘green solution’ to world’s energy problem, ‘next generation of biofuel’, ‘the ultimate in renewable energy’, ‘the biofuel of the future’, ‘potentials for next generation and renewable fuels’”, he added.
Engr. Tsado explained that some of the reasons why alternative sources of fuel should be vigorously considered and pursued include: the rising and unstable cost of petroleum-based energy in the world market; the dwindling petroleum reserves in the world; the restiveness in the oil-producing areas of the world; exacerbated environmental problems; and non-renewability of petroleum as against the renewability of other sources.
“Algae are generally favourable as biofuel feed stock because of their high photosynthetic efficiency, lipid productivity coupled with their rapid reproductive rate. Biodiesel, bioethanol, biomethanol and even biogas can be produced from algae. The use of algae will not compete with economic or food crops like corn, soybean, oil palm etc.
The biodiesel produced through microalgae is environmentally friendly and renewable source of energy. Biodiesel can be used to substitute non-renewable fossil fuels, whose reserves are fast depleting, thereby making them unsustainably expensive”, he clarified.
Engr. Tsado further explained that the use of microalgae biodiesel has several advantages over conventional diesel. For one, it is environmentally friendly, as the carbon dioxide emissions from the combustion of biodiesel are re-absorbed during photosynthesis by the same number of plants from where it was derived. In fact, biodiesel reduces net carbon dioxide emissions in the atmosphere by 78.5% as compared to that of conventional diesel fuel. It is easier to grow microalgae, since they grow faster than terrestrial crops and require a smaller tract of land for cultivation. They can reproduce themselves very fast; doubling their biomass within 24 hours thereby makes its harvest possible in multiple folds in a year, unlike the oil seed producing plants which are harvested once or twice per year. Its oil yield is also higher compared to that of other oil-yielding vegetable crops (soybeans, jathropha, rape seed, sunflower, palm oil, and so on). It yields more oil as much as 15 to 300 times and over 30 times more of fuel per hectare.
He added that microalgae can grow well on waste water or salt water, not necessarily fresh water. Therefore microalgae can be used to treat waste water, whereby the tiny organisms consume nutrients such as nitrogen, potassium and phosphorus, before it can be disposed of safely. “Furthermore, microalgae do not need application of pesticides or herbicides and, even though they are aquatic plant, they do not utilize as much water as the terrestrial crops. There cultivation style does not make it compete with other conventional food crops in terms of land and nutrient use”, he enlightened.
Engr. Tsado also noted that microalgae are also quite versatile in their use. The by-product in the form of glycerin which is obtained from biodiesel production has a great market value as its prime consumers are pharmaceutical, cosmetic and soap industries. The microalgae cake left over in the process can be burnt to produce heat energy or methane gas that can be used for heating or cooking in households.
A Nutritionist in the department of Nutrition and Dietetics, Federal Polytechnic Bida, Niger State, Mrs. Millicent Akpu stated that even though microalgae are tiny, they are still the most nutritious food source. It contains up to 65% of vegetable protein. Amongst the nutritional values, it contains up to 50% of the amino acids that the human body needs, and capable of providing a 90% absorption rate for the human body. Not only can microalgae provide us with nutrition, it can also help us maintain a healthy body, and therefore it has been known as the ‘Green Super Food’ for the 21st century.
She further said that microalgae supplements are a source of energy, protein, and are easy to digest. These supplements are often taken for supporting healthy brain functions, detoxification, and building of the immune system. Some microalgae are used to treat fibromyalgia, high blood pressure, fungal infections, cholesterol-related conditions, and certain types of cancer. The consumption of microalgal biomass as a human health food supplement is currently restricted to only a few species, e.g., Spirulina, Chlorella, Dunalliella, and to a lesser extent, Nostoc and Aphanizomenon. Microalgae are a source of a wide variety of nutrients such as omega-3 fatty acids, and are a particularly large source of protein. Fish oil has become famous for its omega-3 fatty acid content. Microalgae are consumed by prey fish such as sardines and herring, which in turn are consumed by bigger fish. The omega-3 fatty acids from a fish like salmon are not in fact from the salmon, but from the presence of microalgae in the food chain. In other words, fish don’t actually produce omega-3s, instead accumulating their omega-3 reserves by consuming microalgae. These omega-3 fatty acids can be obtained in the human diet directly from the microalgae that produce them.
“Microalgae contain calcium, phosphorus, iron and many other mineral elements, but is also rich in β-carotene, pantothenic acid, folic acid, biotin, vitamin complexes A, B, C and E. Vitamin B12 and iron values are higher in microalgae than our livers, and the calcium values are higher than that of milk.
Due to the complete nutrition values of microalgae, many countries have labeled it as a health food, functional food or dietary supplements. At one time, the Mexican government even made regulations that children’s food must contain 5% of spirulina (an algal specie), and Olympic athletes were to have more than 20% of spirulina in their food. In 1996 The Japanese Health and Nutrition Food Association categorized spirulina and chlorella as health foods, and in 1998 the US Food Development Authority followed by categorizing chlorella and spirulina as dietary supplements”, she added.
A specialist in animal farming, Dr. Ikewe Matthews, revealed that microalgae are also used as feed in the aquaculture of mollusks, crustaceans (shrimp), and fish. Most frequently used species are Chaetoceros, Chlorella, Dunaliella, Isochrysis, Nannochloropsis, and some others.
“Microalgal biomass has also been used with good results (i.e., better immune response, fertility, appearance, weight gain, etc.) as a feed additive for cows, horses, pigs, poultry, and even dogs and cats. The main species used in animal feed are Spirulina, Chlorella and Scenesdesmus.
Microalgae-produced coloring agents are used as natural dyes for food, cosmetics, and research, or as pigments in animal feed. Astaxanthin, a carotenoid produced by Hematococcus pluvialis, has been successfully used as a salmon feed to give the fish meat a pink color preferred by the consumers”, he further expounded.
Engr. David Tsado came in again and said that there are a number of specialty products and chemicals that can be obtained from microalgae. These include bioflocculants, biopolymers and biodegradable plastics, cosmetics, pharmaceuticals and bioactive compounds, polysaccharides, and stable isotopes for research. The market for these specialty products is likely to be very small due to their specialized applications.
A Microbiologist and a co-reseacher with Engr. David Tsado, Mr. Abdulkadir Nda Umar of the same institution, threw more light on the culture of microalgae. He explained that the origin of microalgae and water source should be carefully assessed before consumption of microalgae products, one should also be aware if the production process been affected with heavy metal or radiation contamination. Strict quality control and manufacturing procedures can also avoid possible skin disorders from the consumption of microalgae. Therefore, it is best to choose qualified or certified products that have not been contaminated by heavy metal or pollutants, avoiding the consumption of poisonous elements of entering our bodies. The water source used for cultivating microalgae is vitally important, the water source cannot be polluted or contain heavy metals. Sufficient sunlight will enable the microalgae to create high quality nutrient elements.
“There are many types and species of microalgae, some of which are highly toxic. An incident in Hong Kong known as the red tide, occurred because of poisonous algae had contaminated other algae in the ocean, which created a red color. The sea creatures consumed the algae then became also contaminated. Therefore, cultivation of microalgae should be of pure strand cultivation.
Most microalgae are strictly photosynthetic, i.e., they need light and carbon dioxide as energy and carbon sources. This culture mode is usually called photoautotrophic. Some algae species, however, are capable of growing in darkness and of using organic carbons (such as glucose or acetate) as energy and carbon sources. This culture mode is termed heterotrophic.
Microalgae cultivation using sunlight energy can be carried out in open or covered ponds or closed photobioreactors, based on tubular, flat plate, or other designs. Closed systems are much more expensive than ponds, present significant operating challenges (overheating, fouling), and, due to, among other things, gas exchange limitations. If the algae are destined for consumption, its cultivation using pond system is not advisable for fear of contaminations”, Mr. Umar said.
To cap it up and also to spur someone’s interest in exploring microalgae potentials, Engr. David Tsado suggested that a large number of potential pathways exist for the conversion from algal biomass to fuels. These pathways can be classified into the following three general categories: those that focus on the direct algal production of recoverable fuel molecules (e.g., ethanol, hydrogen, methane, and alkanes) from algae without the need for extraction; those that process whole algal biomass to yield fuel molecules; and those that process algal extracts (e.g., lipids, carbohydrates) to yield fuel molecules.
He further said that there are at least five different options for recovering economic value from the lipid-extracted microalgal biomass. These are: maximum energy recovery from the lipid extracted biomass, with potential use of residuals as soil amendments; recovery of protein from the lipid-extracted biomass for use in food and feed; recovery and utilization of non-fuel lipids; recovery and utilization of carbohydrates from lipid-extracted biomass, and the glycerol from the transesterification of lipids to biodiesel; and recovery/extraction of fuel lipids only, with use of the residual biomass as soil fertilizer and conditioner.
The versatility of microalgae has been x-rayed. However, this will arouse sufficient interest both in the subject area and utilization of algal products, and also researchers. The exploitation of algal resources for commercial products and as alternative sources of energy is strongly advocated. This is a challenge to Nigerians, especially those in the corridor of powers, to make policies that will make a shift from petroleum to other energy resources which is common, familiar and renewable, in the light of low cost of petroleum-based energy in the world market, the dwindling petroleum reserves in the world, and the restiveness in the oil-producing areas of the Niger Delta region of the country. Nigeria should key in to the money-spinning industry as is done in other parts of the world with respect to microalgae resourcefulness.