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Heike Frühwirth brings engineering methods into the hype about algae

Heike Frühwirth is not terribly taken by the euphoria surrounding the potential of algae. She knows better as she has become aware of the potential pitfalls from her own personal experience. Frühwirth was born in the Austrian city of Graz where she also studied process engineering. She has been in charge of process engineering under the industrial biotechnology study programme at Biberach University of Applied Sciences since 2012. She specializes in algae, a biogenic raw material that has inspired many projects. Hardly any other biomass has generated so many expectations in the context of a future bioeconomy.

Heike Frühwirth understands why. She is a child of the 1970s environmental movements and she grew up wanting to save the world, sorting her waste and saving energy. However, Frühwirth, who calls herself an ‘advocate for the environment’, finally opted for a pragmatic approach to saving the world, in an area where she could really make a difference. She studied process engineering at Graz University of Applied Sciences where she soon discovered that she was on the right track as process engineering was basically all about environmental technology.

Biotech liaison starts with doctoral thesis

Algae expert and process engineer Prof. Dr. Heike Frühwirth. © Biberach University of Applied Sciences

Frühwirth came to the field of biotechnology when she did her PhD as part of a EU-funded project on the development of a new method for the purification of bioplastics up to the pilot plant stage. The method involved feeding halophilic archae bacteria with whey, a by-product of cheese-making and giving them an osmotic shock, which is a rather smart way of releasing bacterial proteins, in this case polyhydroxybutyrate (PHB). PHB is a carbon reserve found in some bacteria that can be used for the production of plastics.

After a short postdoctoral period, Frühwirth joined the research department of the biodiesel production plant supplier and biofuels specialist BDI – BioEnergy International AG in 2005 where she was initially responsible for continuing the company’s bioplastics project. However, she soon came up against the hype surrounding algae. Skimming the relevant literature, she found a huge amount of information about fantastic per hectare yields and audacious up-scaling procedures. She then began focussing on the suitability of algae as a source of raw material for biodiesel. 

She screened many microalgae isolates and strains in order to find the ones that grew rapidly and produced large quantities of fat. However, she came to the conclusion that microalgae do not initially appear suitable for the production of biodiesel as they take a great deal of energy to cultivate.

Cardinal problem: a lot of water, few algae

Prof. Dr. Heike Frühwirth knows that algae grow very quickly. © Pytlik/BioRegionUlm

The main problem with algae is that in contrast to yeasts, algae normally mature in a highly diluted state, with a biomass yield of as little as ten grammes per litre of water. “One percent biomass and 99 percent water.” In addition to the low yield, biomass still needs to be converted into oil. Moreover, algae produce not only neutral oils suitable for transesterification and hence biodiesel fuel production, they also contain lipids with polar constituents that are unsuitable as biodiesel feedstock.

Frühwirth’s test series revealed that instead of producing biodiesel, it is far more profitable to use microalgae for producing materials in the high-price range such as omega-3 fatty acids. Frühwirth explains that long-chain (26 carbons) omega-3 fatty acids are excellent nutritional supplements and can also be used as animal feed in order to improve animal health and the quality of meat and eggs. Microalgae therefore have an economic importance that should not be underestimated. 

As head of research at BDI, Frühwirth developed new processes with specifically selected algae from the Erlenmeyer flask stage to the 300-l reactor stage for the operative business with a medium-term perspective. Frühwirth worked with great enthusiasm on basic research-based projects such as the generation of hydrogen from algae.

Expensive radical scavengers

Nevertheless, it was not too hard for her to leave industry when the time came as she swapped market-driven project work for the freedom of research (“it is absolutely fantastic to do something that is so exciting”) – although this came with a rather heavy teaching load. After a year of teaching subjects unrelated to algae, she ended up returning to her speciality area.

In Biberach, Frühwirth used the Haematococcus algae to produce astaxanthin, a red pigment that the unicellular algae produce under situations of stress. Pure astaxanthin is an antioxidant with a selling price of several thousand euros per kilogramme. In addition to being biosynthesised by Haematococcus algae, astaxanthin can also be produced chemically in the laboratory. Frühwirth knows of two companies that use algae to produce astaxanthin.

Frühwirth’s second research focus is on the development of adsorbents. Research with lead and arsenic in Biberach has shown that algae can accumulate heavy metals on their surface. Together with her students, Frühwirth is now planning to carry out research into arsenic adsorption with a specific focus on finding solutions for drinking water problems in Bangladesh. The drinking water collected from wells in these areas is often heavily contaminated with arsenic and represents a major public health risk.

The Biberach project aims to help people to help themselves: “We are looking to develop a simple, robust algae cultivation process so that people can use algae for cleaning their drinking water on site. They would then not need a drinking water treatment plant that consumes a lot of energy.” Meanwhile, the researchers are toying with a number of different concepts in the laboratory. “Many students are interested in improving the world,” says Frühwirth with a smile, apparently recalling her early days as a student in Graz.

Back to the basic shapes

Green stands for hope: algal reactor at Biberach University of Applied Sciences © Biberach University of Applied Sciences

Frühwirth has gone back to what she was doing before and is developing algal reactors once again. In analogy to the research approach used by AlgaePARC in the Dutch city of Wageningen, Frühwirth is now specifically focused on finding the best reactor model and is comparing different culturing systems with one another in order to assess the rate of biosynthesis and the impact of technology on algal growth to obtain an optimal reactor design.

The researchers are also comparing astaxanthin synthesis in different types of reactor and using similar methods to investigate the effect of light. The latter project is being carried out with an energy engineer from Biberach University of Applied Sciences.

Her research follows the procedural notion according to which systems that are used for upscaling need to be physically and geometrically similar. Although from a technical point of view there might not be any problems in upscaling production, Frühwirth is nevertheless aware that biological systems will always be associated with a high degree of uncertainty.

The fact that the automated determination of algal density in a reactor still fails due to trivialities, e.g. gas bubbles and the adherence of the algae to the reactor walls, clearly shows that industrial algae cultivation is still far from technologically mature. The automated harvesting of cells is therefore not possible for technical reasons. In principle, it is fairly easy to measure the density of liquids as long as there are no gas bubbles and the algae do not adhere to the surface. However, if this happens, the measurement of algal density in a three-phase system becomes an enormous technical challenge. 

Water management – a key to economic success

The water balance is another crucial factor in the economic operation of algae reactors. Frühwirth has developed a recycling system that facilitates the treatment of the fermentation supernatant, thus enabling an 1800-hour operation by keeping the water in a closed system for several months.

Given the early stage of development of algae-based bulk production, it is not surprising that many different laboratory approaches come to an abrupt halt when the researchers try to upscale them. However, Frühwirth is convinced that algae are the biomass of the future. Given dwindling supplies of raw materials and residue resources, one huge advantage of algae is that they do not need agricultural land on which to be grown. She believes that algal reactors could be placed on roofs when other types of biomass become expensive. It would then also be possible to run demonstration plants economically. All this is technically feasible as there is enough sunlight, water and CO2.

Algae technology still faces huge challenges

Chlorella algae have a generation time of around 20 hours; one mature cell divides into four new ones every 20 hours or so. © Pytlik/BioRegionUlm

But all this is still just a pipedream. Frühwirth is convinced that algae can be used in the high-price segment, for example for the production of omega-3 fatty acids that could be produced directly without having to use fish oil. However, technical solutions for managing the water cycle need to be developed. She also believes that the production of omega-3 fatty acids from algae would achieve a relatively good ecobalance.

The algae expert from Biberach believes that the mass production of algae will in principle be possible in the medium to long term, and that it will be another four to five decades before the technology is mature enough. The algae will then be able to live up to their potential because they use sunlight more efficiently than land plants. Frühwirth knows that algal biotechnology needs to overcome four major challenges before the production of algal biomass becomes economically feasible on the industrial scale: water treatment (water cycle), temperature increase due to sunlight, the still low level of automation and energy use that is not yet optimized for the operation of algal plants.

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