Feedstock of the future

The air in the 600-square-meter building is pleasantly fresh. A reddish hue emanates from 11 steel and glass production lines where microalgae are thriving under LED lights. Borna Semenjuk dips a pH sensor into a 30-liter glass cylinder where algae are forming at the head of a big cultivation line. There’s a deep green shimmering through the glass. The production engineer points to a fine line of these single-cell organisms that have settled on the cylinder wall. “The algae are agglomerating because they don’t have enough carbon,” says the 26-yearold, who then glances at the display: 6.6 – indeed a bit on the low side. He presses a button on the wall, and fine CO2 bubbles effervesce through the cylinder.

While training as a food technologist a few years ago, Semenjuk learned how to banish algae. Now he does everything to help them proliferate. The right mix of nutrients, heat, illumination and CO2 keeps the microorganisms happy. In a matter of days, the chlorella in this glass cylinder will have multiplied to the point where they can be moved to intermediate storage in two progressively larger tanks and then decanted into one of the eleven 10,000-liter production lines.

Semenjuk works for Phyox in Novska, which is a good hour’s drive from the Croatian capital Zagreb. Here the company has been manufacturing dry powder from chlorella algae for the pharmaceutical, cosmetics and food industries since late 2022. Phyox is involved both in customer business and on the development side. It aims to create ideal conditions for the industrial production of algae and plans to increase capacity twentyfold in the near future. This would make Phyox one of the world’s larger manufacturers, if not the largest, of high-purity microalgae powder.

While other producers grow algae outdoors in open tanks or closed glass tubes, Phyox has moved its manufacturing to proprietary indoor bioreactors. Water containing the algae meanders past LED strip lighting with an intensity and pulse rate precisely tailored to the needs of cultivating the chlorella algae. Fine nozzles on the bioreactor floor pump in a blend of oxygen and carbon dioxide, ensuring even distribution of warmth and nutrients while steadily propelling the liquid forward. At the end of the line, algae in suspension are pumped back to the start and continue repeating their transit until a turbidity sensor indicates that it is time for the harvest. A separator then extracts algae from the water and the permeate – the filtered water – flows back to the line, where it is manually replenished with fresh stock.

“Phyox’s visionary ideas fascinated me from the start,” says Christian Fischer of Endress+Hauser Germany. “This kind of production is not dependent on the sun or the seasons. Nor are there any contamination risks, unlike with open tanks,” adds the technical sales manager, who has been helping to oversee the project since its inception. So Phyox can continue manufacturing 24 hours a day, 365 days a year in a highly controlled environment, he says. Along with process instrumentation, Endress+Hauser also supplied the automation solution including remote access.

All this allows Phyox to do more than just make a high-purity product and maximize production yields. “We can also cultivate microalgae with very specific properties for precise customer requirements.” Indeed, the focus has long since shifted away from algae as a straightforward generic product and toward individual extracts such as carotene and lutein. Adding just a single gram of phosphate to the nutrient mix can make the difference here. “Every measurement value is a field of research in its own right,” says Herrmann, who aims to take the facility to the next level by creating a fully automated and digitalized ‘plant 5.0’ for up to 15 different varieties of microalgae. The plan is also to use artificial intelligence to ensure optimum cultivation conditions.

Algae are both sensitive and highly diverse organisms. For example, while chlorella must be vigorously agitated to prevent adhering to the glass cylinder wall, dunaliella drift freely through the water. Some varieties of algae need a lot of light, others prefer it a little darker. Herrmann regrets the lack of support from academic research: “Most of the work to date has been with small quantities, so it’s not particularly useful for volume production.” With its planned expansion, Phyox therefore wants to build a campus for algae research. The goal is to develop the largest algae cultivation plant in the world with scientifically based, highly automated production.

The fact that this is a realistic vision is evident from the interest shown by investors as well as industrial and research partners worldwide. And the chlorella algae at Phyox give a helping hand too. In a natural habitat, the organisms reach around five to eight micrometers in diameter. But at Phyox, they grow three to five times that size. “Without losing any of their constituents,” says Herrmann. “And right now, we only know a fraction of what there is to learn about algae,” he adds with a smile.