Two research groups, one in Curitiba in Paraná, and the other in São Carlos, in the interior of São Paulo, are developing new technologies to produce biofuels from microalgae. These single-celled aquatic organisms, which are among the oldest on the planet, reproduce rapidly and are powerhouses for the production of biomass and bioactive compounds. In addition to performing photosynthesis like plants, and utilizing sunlight and carbon dioxide (CO2) from the atmosphere, they can use organic sources of carbon found in waste. As a result, as long as they are in suitable lighting and temperature conditions, they produce oxygen and organic materials from which, through various separation processes, chemical compounds used as fuel, cosmetics or food supplements can be extracted. In the laboratory and in experimental plants, microorganisms have demonstrated the ability to feed themselves on waste – from the production of oil and ethanol or even from raising animals, such as pigs, among others – and convert it into useful and environmentally acceptable chemical compounds. In any case, there is still great difficulty in increasing the volume of production.
The Center for Sustainable Energy Self-Research and Development at the Federal University of Parana (NPDEAS-UFPR) is conducting experiments in an attempt to overcome this problem. The group’s long-term goal is to produce green diesel, a biofuel with a similar composition to petroleum diesel. One study uses industrial-scale photobioreactors with a capacity of 12,000 litres. The first step is to produce biomass from microalgae in this equipment. Once harvested, the material is dried and dissolved in a hot solvent consisting of a mixture of chemical compounds. In the next step, the researchers remove the solvent and, through distillation, separate the resulting oils.
Preliminary results indicate that the conversion rate of the microalgae Tetradesmus obliquus concentrate into crude oil could reach 25%, a significant jump from the current 10%. “It’s going well,” says petroleum and chemical engineer Yago Gomez Costa, who is in charge of the work. “We are in the process of adjusting the temperature range, but we have already been able to recover the solvent from the concentrate, which can be reused, and separate the oil fractions.”
As detailed in a September article in the journal Environmental Management, by distilling crude algal oil, the researchers obtained 25 different compounds, including hydrocarbons such as alkanes, used in cooking gas and gasoline, and alkenes, the basic materials for plastic packaging. . UFPR’s research is one of the few in the country that goes beyond the stage of biomass production from microalgae.
Another possibility of producing biofuel using microalgae is being evaluated in the laboratory of biologist Ana Teresa Lombardi, from the Federal University of São Carlos (UFSCar). At the beginning of September, in one of the laboratory rooms, the first test was carried out on a slightly larger scale, in a 20-litre tank. The goal was to increase oil production from microalgae, perhaps to 70%, as has already been verified in smaller-scale tests, through a process the team has patented.
“We have achieved great results by stimulating microalgae with specific nutrients, so that growth and generation of biomass with a high oil content are maintained,” says Lombardi. “The traditional approach is to expose them to stress, which stops growth.” The UFSCar researcher plans to transfer her findings to industrial applications.
Working independently, the UFPR and UFSCar teams are renewing scientific and technological interest in microalgae. About 15 years ago, they were seen as an alternative for reducing excess carbon dioxide in the atmosphere, turning it into biofuels that could be used in cars, planes and ships, with lower polluting emissions than fossil fuels.
However, the algae did not show the desired yield. It also became clear that production on a commercial scale would not be feasible and that the final price would be more than double the price of petroleum derivatives. As a result, many companies that invested in producing biofuels from these microorganisms have closed or refocused their research. “The big difficulty is moving from the laboratory production scale, from 100 to 1,000 litres, to the industrial scale, from 10,000 liters and above,” comments agronomist Sergio Goldemberg. In the laboratory, teams from research centers and companies have determined the best temperature and light ranges and nutrient combinations for microalgae to create the mass from which commercially important compounds are extracted. However, as production increased to 10 or 20 times larger volumes, it became more difficult to maintain a stable temperature, because biodigestion generates heat. As a result, the risk of bacterial contamination increased and production decreased, making the process infeasible.
In 2009, Goldemberg founded one of the few companies in this field in Brazil, Algae Biotechnologia. For years, Algae has maintained support from research funding agencies, including FAPESP. In 2014, a project was started at InterCement, part of the Camargo Corrêa group, to use carbon dioxide generated from microalgae produced in cement production. After a few years, the contract to continue the research was not renewed, and in September of this year, InterCement began an extrajudicial recovery process.
The foliar fertilizer for supplying micronutrients and the action of plant biostimulants produced by microorganisms, developed by the two companies, showed good results in the laboratory. But difficulty obtaining funding for field tests caused work to halt. “We use stillness [resíduo da produção de açúcar e álcool] To grow microalgae, but we faced many technical difficulties.” In 2019, without clients, Goldemberg closed the company.
Biologist Silvia Helena Giovone Brondi faced a similar situation. In 2020, with the support of FAPESP, an orange pigment, carotenoids important for human health, was obtained from microalgae such as Chlorella vulgaris, but it could not avoid temperature fluctuations in the process, which harms production. “The equipment is expensive,” she says. Without additional funding, he also closed his company, AlgaeTech Pesquisa, in São Carlos.
Companies for niche markets still exist, using microalgae to produce cosmetic and food ingredients, such as the pigments that give the pink color to captive-raised salmon. In Brazil, Fazenda Tamanduá, in Santa Teresinha (PB), and Ocean Drop, in Balneário Camboriú (SC), both produce spirulina (Arthrospira platensis). Relatively simple processed microalgae can be used as a nutritional supplement because it is a rich source of proteins, minerals, B vitamins, iron and antioxidants. In Orindiova (SP), Terravia, a subsidiary of a US-based multinational company, uses microalgae that consumes sucrose from sugar cane to produce fatty acids, a type of oil used as an ingredient in soaps and facial creams.
The possibilities of using microalgae for the use of industrial and agricultural wastes and effluents are also emerging. During his postdoctoral training at UFSCar, fisheries engineer Lucas Guimarães Cardoso, in partnership with the Lombardi team, developed a process that uses microalgae to treat so-called produced water. The liquid, loaded with minerals, oil, chemicals and gases, is used to raise oil from wells to the surface.
In 1.5-liter bioreactors containing cultures of Chlorella vulgaris, the group found that microalgae consume (feed off) compounds present in the produced water. From this experiment, they have produced two sets of commercially valuable products: linoleic and palmitoleic acids, which are part of biodiesel, and carbohydrates and proteins, which can be used to produce ethanol. Researchers were also able to remove heavy metals such as copper, manganese, and molybdenum from produced water, as detailed in a 2022 article published in Environmental Technology and Innovation.
From that year on, he was appointed as a professor at the University of El Salvador (Unifacs), in Bahia, and in the graduate program in Chemical Engineering at the Federal University of Bahia (UFBA), Cardoso continued his research. At an international biotechnology conference, held in August in Florianopolis, he presented a discovery to chemical engineer Ingrid Rocha Teixeira, his doctoral advisor: fed with a solution of 50% produced water and 50% crude glycerol, the microalga Phaeodactylum tricornutum removed heavy residues more efficiently. . metals and produced a biodegradable polymer that could be an alternative to traditional plastics. “I intend to present the results next November to the companies that supply us with oil exploration waste,” he says.
In another experiment, Cardoso and the group of food engineer Jorge Alberto Vieira Costa, of the Federal University of Rio Grande (FORGE), in Rio Grande do Sul, found that two species of microalgae, Spirulina sp. Chlorella fusca, which grows in brackish water, produces fats and carbohydrates, respectively, as reported in a 2022 article in Bioresource Technology. In collaboration with colleagues from the Semi-Arid Unit of the Brazilian Agricultural Research Foundation (Embrapa) and with support from the Ministry of Science, Technology and Innovation (MCTI), Costa is preparing a pilot unit to be built in Petrolina (PE) for the production of microalgae. Food, feed, fertilizer and drinking water are brackish, common in remote areas of the northeast of the country.
Another strategy for absorbing pollutants from polluted water is porous charcoal obtained by gently heating a mass of microalgae. The method was developed by the Forge group and detailed in an article in Enzyme and Microbial Technology, in 2023. Costa, the group’s coordinator, who has worked in this field for 30 years, is optimistic: “The pressure from legislation to use waste is increasing in Brazil.”
Microalgae also seem to enjoy waste, such as pig and poultry manure, which the UFPR NPDEAS team diluted and used as nutrients for these microscopic organisms. “It grew faster, in three days, instead of 15,” said industrial pharmacist Andre Belén Mariano, deputy coordinator of the group, also composed of postdoctoral student Ihna de Aguiar Severo. The research is being conducted on a pilot scale using a 6,000-litre bio-digester. Microalgae removed 99% of the phosphorus and nitrogen from waste and produced water that could be used to quench the thirst of farm animals. “Despite the good results, we still have challenging aspects to work on in many waste utilization processes using microalgae,” he comments.
The above report, “The Many Uses of Microalgae,” was published in print edition No. 345, November 2024.
Projects 1. Bioprospecting, characterization and improvement of Brazilian microalgae for CO2 biofixation and production of biomolecules of commercial interest (No. 18/07988-5); Thematic project of the method; Researcher in charge Anna Teresa Lombardi (UFSCar); Investment: R$3,011,694.89. 2. Identification of the best cultivation systems to expand the range of new microalgae species (species selected in previous phases of the thematic project) (No. 20/15688-1); Postdoctoral method. Researcher in charge Anna Teresa Lombardi (UFSCar); Lucas Guimarães Cardoso Scholarship; Investment: R$153,834.88. 3. Cultivation of microalgae Chlorella sorokiniana and Chlorella vulgaris for the production of carotenoids and proteins to serve the pharmaceutical, food, cosmetics and fine chemical industries (No. 17/50360-4). Innovative research method in small companies (pipe); Responsible researcher Silvia Helena Giovone Brondi; Investment: R$431,085.08. FAPESP Research Journal
