SCHOTT solutions no. 2/2016 > Focus / Science

Photo: ecoduna

Hanging gardens

Light is energy. This can be directly observed in the growth of microalgae in photobioreactors. The harvests increase significantly when glass tubing from SCHOTT is used.

Alexander Lopez

Microalgae offer the industry an interesting future market. These green unicellular organisms can convert light into biomass five times more efficiently than land plants. They are rich in valuable ingredients and are very versatile, for example, as a food supplement or in the field of cosmetics, food and feed, biofuel, fertilizer and even as ingredient substances for drugs. The market volume of algae production has already exceeded the one billion US dollar mark and continues to grow fast.

Photo: SCHOTT

Why algae?

There is a huge range of applications for algae – from medicine to agriculture. Here are three particularly interesting examples:

1. In cosmetics: Algae contain a high share of proteins. They can provide the skin with energy and prevent it from drying out.

2. For water treatment: Inorganic substances like nitrates and phosphates can be removed by precipitation with the aid of chemical agents, or – in a ‘greener’ way – they can serve as nutrition for algae in a controlled manner and thus be removed before the water is discharged.

3. As dietary supplements: The active ingredient astaxanthin is extracted from algae and sold as a dietary supplement because of its health benefits.

By using high-quality, round DURAN^® glass tubing from SCHOTT, the light that algae need for photosynthesis can be put to better use in photobioreactors. Tubes and multiple distributors are also ideally suited for constructing state-of-the-art vertical photobioreactors. Photo: ecoduna

When it comes to harvest volumes, the material that the photobioreactors are made of plays an important role. Algae manufacturers are increasingly replacing plastic components in their photobioreactors with components made of glass. Glass is easier to clean, has a long service life and is very transparent, important parameters that affect output and the costs of large scale algae production. With plastic-based systems, however, a biofilm gradually forms on the walls over time. The reason is the bacteria that accumulate, grow and eventually lead to contamination of the biomass. To prevent this, regular cleaning is necessary and the production systems need to be switched off. High-quality DURAN^® glass tubing from SCHOTT has very smooth inner surfaces that strongly reduce biofilm formation and make continuous cultivation possible on an industrial scale 365 days of the year. ”Bacteria are algae’s enemies, and the scratches that are common on the inside of the plastic surface after many cleaning cycles make for the perfect breeding ground for those enemies. Thanks to the robustness of SCHOTT’s glass tubing, the photobioreactors offer consistently good production conditions without the risk of contamination,” says Johann Mörwald, CEO of ecoduna. The Austrian company produces and harvests different algae such as chlorella or spirulina, a blue-green algae used for dietary supplements and animal feeds, in vertical photobioreactors.

”Using glass tubing in our ’hanging gardens’ has proved to be a smart investment that lowers our operating expenses and practically eliminates replacement costs.” – Johann Mörwald, CEO of ecoduna. Photo: ecoduna

The world-patented vertical photobioreactors, which ecoduna also refers to as ”hanging gardens,” also eliminate pumps. CO₂ and nutrients are introduced continuously at the bottom. This is highly efficient and guarantees maximum purity.

Ecoduna recently changed its production technology at its plant in Austria from plastic to SCHOTT glass tubes 65 mm in diameter. The photobioreactors have been running continuously since the switch was made. For the company, this means higher yields and lower operating costs. The material’s longevity is also one of its key advantages; ecoduna says it used to plan to replace the plastic elements about every ten years. Now, thanks to an estimated 50-year lifespan of the glass tubing, having to replace the entire system is far less of a concern.

Algae are especially popular for the usage in cosmetics. They contain a high share of proteins, they can provide the skin with energy and protect it from draining. Photos: Thinkstock; Fotolia

Higher output – lower costs

Ecoduna plans to use glass tubing at its new production facility in Austria and in another facility in Denmark that the company operates together with a partner.

Commercial algae producers constantly work to improve biomass yields and harvests. Glass tubing has proven to be extremely effective in both horizontal and vertical photobioreactors because its robustness and cleanliness extend the lifespan of these systems by multiple factors. SCHOTT will continue to work with companies like ecoduna in the future to find ways to improve system efficiencies, boost algae growth, and increase biomass yields. —

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