A rich source of polyunsaturated fatty acids, proteins, enzymes, vitamins, minerals and trace elements, it’s not surprising that algae has become a highly sought after raw material for numerous products in the pharma, chemical and food sectors. For more than 50 years, GEA has accompanied start-ups and algae producers with R&D support and high-quality and processing technologies that meet strict industry standards.
The most important consumer of CO2 on our planet, 1 kilogram of algae biomass is able to store around 2 kilograms of CO2 while simultaneously releasing 1.6 kilograms of oxygen. In addition to this very important job, the applications in which algae are used are extensive, including everything from toothpaste, shoe polish, facial cream, animal feed, food and food supplements, natural food colorants, bio fertilizer, soil conditioners, in wastewater treatment and as a binder of heavy metals. And the list is growing.
Existing in either marine or freshwater form, algae are further classified according to size – macro or microalgae – and by color: blue, green, brown or red. Macroalgae include larger aquatic plants such as kelp and seaweed varieties which can grow up to 50 meters long. Microalgae, which includes for example, Chlorella and Spirulina:
- Are generally microscopic single cell organisms (average cell size between 2-10 micrometers)
- Have no roots, stems or leaves
- Can be cultivated in photo-bioreactors (PBRs) or in open ponds and fed on wastewater, including sewage, or cultivated via heterotrophic fermentation, whereby the algae is fed on sugars rather than sunlight
- Cultivation can take place on lands unsuitable for food crops and therefore do not compete with food production
Processing, or harvesting, is necessary to separate the algal biomass from the water it was grown in – a field GEA has been active in since the 1960s, with technologies for concentrating, extracting and washing algae, as well as drying.
From a nutritional standpoint, algae are hard to beat. Fish, like salmon, for example, contain beneficial omega-3 fish oils, but do not produce it naturally, but rather via the consumption of microalgae. That means algal oil has even more potential to support global nutritional needs and can help take pressure off the global fish supply, for example, if it is more widely used in fishmeal. Likewise, increasing demand for reliable, sustainable, and low cost sources of energy and biodegradable plastics are major factors expected to drive growth in this exciting sector.
Gently, gently: Putting the brakes on shear to increase algae survival rates
Modern algae processing requires centrifugal technology to concentrate, extract and wash the harvested algae suspensions. Due to the biological make up of algae, centrifuges are often the only economical means by which to efficiently process microalgae, not only because they use less energy than ceramic membrane filtration, but also because cell size causes binding or blockage in traditional rotatory vacuum filters.
That said, a centrifuge means centrifugal force, and keeping algae cells alive while they are exposed to up to 15,000 g-force can be tricky. During this process, there are two critical steps: getting the cells into the centrifugal field and getting them out again. GEA solved the challenge of feeding sensitive cells into a rotating system several years ago with its patented hydrohermetic feed system. The system consists of a disc at the end of a feed tube that feeds the cells underneath the liquid level in the pre-filled bowl – similar to the effect achieved when further filling a bucket with water whereby the hose fills the container from below the water’s surface, which eliminates splashing.
More recently, GEA developed a much-needed solution for discharging extremely shear-sensitive cells like Diatoms and Haptophyta from the rotating system without damaging or destroying them, given mortality rates can reach more than 90 percent even at reduced speeds. Most processed products can handle rough treatment without any negative effect, and during normal ejection, the bowl is opened while operating at full or reduced speed and the gathered solids are simply shot out into the catcher.
In the case of algae, the centrifuge concentrates the cells and collects them during operation in the solids holding space at the bowl periphery – the exact spot in the centrifuge where centrifugal forces are highest. The key to GEA’s solution was finding a way to slow the solids down during discharge, thus reducing the speed with which the cells collide against the catcher wall. This led to the development of the GEA hydro brake assist ejection system. The brake assist functions as a curtain of fluid through which the solids are ejected. Created by mounting a series of spray nozzles on the catcher, as soon as the piston is activated, the control system triggers the nozzles and a curtain of fluid is sprayed down into the catcher, substantially slowing or braking the ejection speed of the solids. The fluid used is normally water, however the separated clear phase can also be employed. Because the nozzles spray only briefly when the second the piston is activated, re-diluting the concentrated algae can be mitigated.
Reduction of product losses from 95 to 2 percent with a new feature
In 2018, OP Bio Factory in Japan, which researches and develops natural products from marine resources for use in potential drugs and functional substances, began using the new GEA hydro brake. With a conventional ejection system, 95 percent of the customer’s algae cells were being destroyed during discharge. With the new assist feature their algae cell losses have been reduced to just 2 percent, representing a massive improvement in costs and efficiency. So now OP Bio Factory can successfully process even the most sensitive algae cells with centrifuges.
Partnering to meet growing global demand for algae products
For start-ups and businesses in the algae industry, funding is key to moving from the laboratory to the pilot phase. Investors generally want some evidence that demonstrates that a given technology works on a small scale or can be scaled up to produce several tons of algal biomass or gallons of algal oil before committing funds. Key factors in successfully scaling up algae production and processing are reducing energy consumption and operating costs.
Since 2015, GEA has supported a French bio-technology start-up, beginning with onsite separation trials. Working together, GEA helped the customer develop a customized algae harvesting process that produces high quality biomass microalgae at industrial scale for use in animal nutrition, food and cosmetics. The GEA viscon® nozzle separator, for example, is being used in heterotrophic microalgae separation, resulting in homogeneous algae concentrate with maximum dry matter using a fully-CIP-able machine for high separation efficiency.
Dutch company Duplaco is also leveraging GEA separation know-how to process Chlorella microalgae, grown via heterotrophic fermentation, which can be used in the production of healthy foods, like smoothies, algae burgers or pasta, in food supplements or animal feed. GEA solutions help ensure that Duplaco’s algae powder and food supplements are of high quality with maximum consistency, while minimizing the producer’s energy costs and production footprint.
Being able to partner customers early on is critical when it comes to developing algae harvesting processes, particularly given the demands to drive down production and per unit costs.”- Alexander Piek, Application Manager - Separation, Algae, GEA Renewables
The growing focus on refining algae to support sustainable food production has drawn GEA and several partners from the EU’s scientific and business community to form the Sustainable Algae Biorefinery for Agriculture and Aquaculture (SABANA) project in 2016. An EU-funded Horizon 2020 initiative, the team has developed a large-scale integrated microalgae-based biorefinery for the production of feed and feed additives, including biostimulants, biofertilizers and biopesticides, by demonstrating the technical, environmental and social feasibility of producing valuable algae bi-products using only marine water and wastewater as a nutrients source.*
In the biopesticide workstream, the team is growing, testing and processing strains of algae that have antimicrobial agents that fight against various plant pathogens. In order to process the sensitive biomass, GEA has supplied expertise and equipment, including centrifuges for harvesting and concentrating the microalgae; homogenizers for cell disruption and a spray dryer for biomass drying so that the active agents can then be tested, the results of which will be available at the end of 2021.
GEA has the right tool for the job
For the concentration process GEA offers several separators and decanters to choose from, each with individual advantages and according to algae type and cultivation conditions. Choosing a separator also depends on the capacities to be handled, product viscosity, the solids content, the pH value in the fermentation broth and cell structure. For the further concentration and dewatering of biomass or classifying microalgae, a GEA decanter is the next step in processing.
When it comes to processing red and green microalgae, GEA homogenizers are ideal, as they deliver the extreme high quality raw material required for food and vitamin supplements as well as biomaterial or bioplastics. This technology ensures reliable and long-lasting components that meet aseptic requirements and products that are fully compliant with all regulations. Homogenization is a mechanical process which breaks the outer cell wall with up to 1500 bar to release the intracellular fluid. It offers advantages in terms of reliability and recouping total costs of ownership, given:
- It is a quick and continuous process
- The results obtained in the laboratory are 100% reproducible at an industrial scale
- The pressure can be varied to find the right degree of cell rupture
- There is no chance of contamination of the product by other substances
While centrifuges can remove most of the free water from algae suspensions, some applications require algae powder which necessitates spray drying. Dry algae powder is a high-quality protein and can be used, for example, as an additive in animal feed.
* This project has received funding from the European Union’s Horizon 2020 Research and Innovation program under the Grant Agreement No. 727874.