‘Engineered’ not just built
A new photobioreactor project from OPBio Factory and Varicon Aqua involving DURAN® glass tubing advances sustainable algae production in Okinawa, Japan.
Despite all frugality, there is one thing that algae needs in vast quantities to grow: light. In enclosed tubular photobioreactors (PBR), algae absorbs all the sunlight close to the internal surface of the glass tubing so that it is already dark a few millimeters into the culture. The mixing rate, total length of PBR and many other factors influence this light-to-dark ratio. Striking the optimal balance is key to optimizing the efficiency of the process. Scientists have therefore developed photobioreactors (PBR) to grow microalgae in large quantities for industrial purposes. These diverse microorganisms are rich in valuable ingredients and very versatile. They can be used in applications such as a food supplement or in the field of cosmetics.
OPBio Factory Co. Ltd. is at the forefront of micro algae innovation in Japan. Together with the expertise of the PBR manufacturer Varicon Aqua, the company has created a custom designed tubular photobioreactor (Phyco-Flow™) on Okinawa island. This particular PBR is undoubtedly one of the most complex systems Varicon Aqua has ever built. We spoke to Joe McDonald, Managing Director at Varicon Aqua, about the development of this extraordinary algae project.
What can you tell us about the project background and its creation?
Varicon Aqua has already completed several complex projects before. In total, we have over 15 years of experience and have completed over 250 projects worldwide. However, this particular Japanese project is quite special due to its complexity. The degree of engineering that went into this makes it unique in a long history of projects. Thanks to the close collaboration with Akihiko Kanamoto, the CEO of OPBio Factory Co. Ltd., we managed to create a bespoke design tubular photobioreactor so-called Phyco-Flow™ – in two distinct project phases. First, we designed and installed 2 x 1,100 litre Phyco-Flow™ photobioreactors. This was followed by the installation of another 2 x 7,000 litre photobioreactors.
What was particularly challenging during this project?
The unique weather conditions in Okinawa was one particular challenge that we faced. By using SCHOTT glass components, the Phyco-Flows™ are enclosed within two aluminum frames affixed with stainless steel mesh to protect the photobioreactors and their components from the notorious Okinawa typhoons. The Phyco-Flow™ systems are now referred to affectionately as Typhoon no. 1 – no. 4. In total, each phase contains 5,000 meters of SCHOTT glass tubing.
Are there any further special engineering details that you would like to share with us?
The Phyco-Flow™ incorporate many elements, including fully automated shading and cooling, with associated data acquisition and control for both monitoring and control of the four photobioreactors. We installed all of the process control elements within the main laboratory facility with all flow and return systems gantry mounted between the internal and external elements. The cooling system utilizes a combination of water chillers and chill recovery with mechanical filtration and recycling via ion exchange systems. This approach mitigates the accumulation of precipitates on the external surfaces of the DURAN® tubing thereby maintaining extremely high levels of light transmission into the biological process. This is of particular importance, as it brings the right amount of light to these algae.
What kind of algae was used for this project?
The algae organism of choice is an extremely fragile and sensitive species known as Pavlova sp, renowned for the high value of a key secondary metabolites such as carotenoids. This particular algae type can be used in areas such as aquaculture, nutraceuticals, functional foods and cosmetics. Given the fragility and sensitivity of the client’s strain to shear and light stress, it was extremely important to fully engineer the project. Computational fluid dynamics is a key tool in our arsenal and is used routinely to determine the suitability and limitations of various configurations. For example, it enables the determination of various height-to-length ratios and plays a key role in the selection of an appropriate pumping solution.
Is there anything else you had to consider?
Another key element is the stability of temperature, minute by minute, as well as diurnally, especially when photosynthesis is reliant upon natural daylight and the influence of seasonal weather conditions. We took a similar robust approach to the design of the temperature control systems. We have run many detailed models for a range of geographic locations and environmental conditions. Over many projects, we compared the empirical data with our models, constantly refining the model inputs to enable higher levels of confidence in each project design. We’re pleased to say that our systems are ‘Engineered,’ not just built. The data assists us in determining the thermal load for worst-case scenarios and the flows necessary to maintain optimal conditions for the microalgae.
How did you ensure that this complex and customized project turned out to be successful?
There are many detailed elements to this project, and the interplay of each element is key to the overall success of the designs. We are very fortunate in this case to have a client who has been fully engaged with this project from day one. He has been heavily involved in many of the design discussions to ensure that we deliver what the company envisions. Akihiko Kanamoto is a very ‘hands-on’ CEO and is extremely well-informed on all aspects of engineering and biology.
What’s next? Are further steps planned?
We are happy to say that OpBio is very pleased with the performance and ease of operation of the four Phyco-Flow™ systems. So much so that I already met again with Akihiko Kanamoto in Okayama in mid-September to discuss and agree on the next steps for capacity expansion that are already planned. We hope to start phase three of this project in 2020.
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