Algae flourish in fish farming wastewater and produce valuable materials – AI models intensify the process
The Midas project, a collaboration between the Ģֱ’s Faculty of Information Technology and Department of Biological and Environmental Science and the VTT Technical Research Centre of Finland, studies algae biotechnology and how it could be intensified.
In the project, green algae are cultivated in connection with the recirculating aquaculture systems. These systems are modern fish farms that use a variety of filtration techniques to allow reuse of the process water in fish tanks. The purpose is for algae to grow and receive the nutrition they need from the wastewater of fish farms.
Academy Research Fellow Pauliina Salmi from the Faculty of Information Technology leads the consortium. She says that algal biotechnology is a growing field of technology that also has significant commercial potential.
“You can get almost everything from algae that you get from fossil oil,” Salmi says.
“Algae can be used as food and a source of pigments. As they grow, algae bind plenty of carbon dioxide and nutrients dissolved in water. Moreover, you can get hydrogen from them and use it in the production of fuels.”
The Midas project focuses especially on cultivating the species of green algae that produce hydrogen and testing new algae for the production of hydrogen. Hydrogen raises interest both as a fuel and for use in the refining processes of fuels.
Algae can give salmonids a red colour
Producing hydrogen with algae is not as efficient as with the most important industrial methods so the scale of hydrogen production in the process is much smaller. However, in the process used in the research, algae grows as a side product of the fish farming industry as if by itself.
“In certain living conditions, algae produce hydrogen naturally and the needed technology is simple,” Salmi says.
“On the other hand, the growth of algae must be monitored continuously so that it is possible to improve the efficiency of cultivation and ensure that the algae are growing in the desired manner so that they will have a good concentration of valuable biomolecules.”
In addition to producing hydrogen, the project has, among others, tested the production of valuable astaxanthin pigment from green algae. Astaxanthin produces the red meat colour of salmon. Currently, the astaxanthin used in the farming of salmonid fish is synthetic, but the pigment produced by green algae would decrease the need to use synthetic products.
Automated growth monitoring with artificial intelligence
In the project, the role of the Faculty of Information Technology is to develop monitoring methods to support the process management so that the quality of the algal biomass can be monitored effectively.
The growth of the algae and the production of biomolecules is monitored using spectroscopy and artificial intelligence. The purpose is to automate the whole process and for artificial intelligence to identify the issues that possibly threaten the growth of algae and, vice versa, the issues that are beneficial for their growth.
“In the current commercial production of algae, monitoring is arranged by taking individual samples from the reactors in which algae grow,” Salmi says. “After that, the samples are analysed in a laboratory. Monitoring this way is expensive and haphazard, and samples cannot be taken from very large volumes of algae.”
The methods developed in the project are non-invasive. No sampling is needed and sensors monitor the quality of the algal culture without disrupting the growth.
If the new methods prove to be efficient, they will be much more effortless and efficient than those currently in commercial use.
“Monitoring based on artificial intelligence and, for example, a spectral camera is efficient because it enables the monitoring of the whole algal culture in real time,” says Salmi. “This makes it possible to react to different changes in algal growth exactly at the right time.”
In principle, these monitoring methods could also be used for traditional algal cultures. However, in this project the focus is on green algae grown in connection of recirculating fish farming.
Practical applications of the circular economy support environmental protection
Contrary to traditional fish farming, in the recirculating fish farms the fish are grown in tanks that use only a small amount of new water while the used water is filtered and recirculated back to the fish with pumps.
Recirculating aquaculture enables nutrients to accumulate in the system to the extent it is possible to grow algae.
“The perspective of circular economy in this project comes especially from how we utilise waste from a system to produce new biomass,” says Senior Lecturer Juhani Pirhonen from Department of Biological and Environmental Science. “This means that when fish are fed, their metabolism produces nutrients in the water, and these nutrients are utilised for the algal culture.”
Instead of chemically cleaning the nutrient-rich water that comes as a by-product of fish farming, the algae growing in the wastewater absorbs the nutrients for better use.
As such, the mere cultivation of algae as part of recirculating aquaculture would be beneficial, but algae are also good carbon sinks.
“I would say that in this project we build a concept that we can utilise commercially in fish farming and possibly also elsewhere, where carbon dioxide is a by-product of industry,” Salmi says.
This project has received funding from the European Union – NextGenerationEU instrument.
