Objective:
Together with its partners Erwin Sander Elektroapparatebau GmbH and KS VTCtech GmbH, the Alfred Wegener Institute (AWI) is developing and testing an integrated aquaculture system based on recirculating aquaculture systems (RAS).
The project aims to combine the breeding of fast-growing marine warm-water species, the giant grouper (Epinephelus lanceolatus) and the tropical saltwater shrimp Litopenaeus vannamei, with the production of salt-tolerant plants and the carbonization of solid waste.
The OptiRAS concept: Effective use of residual flows in integrated saltwater aquaculture. Graphic: Bert Wecker
The intelligent linking of material flows from land-based warm-water marine animal farming will result in the creation of new, commercially interesting products, but above all, it will significantly optimize the nutrient and particle loads of wastewater and waste streams and prepare them for feed-in.
As part of the project, scientific experiments with giant grouper and shrimp at the AWI will first be used to develop the basic data for the structural and production-related design of the pilot plant. With regard to the cultivation of salt-tolerant plants, different cultivation methods will be investigated and the rearing parameters for interesting candidates will be determined. In addition, the material and energy flows of halophyte and aquatic animal farming will be recorded. The analysis of this data will be incorporated into the structural design of the pilot plant.
Erwin Sander Elektroapparatebau GmbH will be responsible for constructing the pilot plant. In addition to the design and construction of both breeding areas, the coupling of animal and plant breeding and the test run on an application-oriented scale will be carried out here.
In order to make sensible and effective use of the residues produced in the production of marine fish, shrimp, and halophytes (feces, bacterial biomass, plant material, other residues), the project will investigate the carbonization of these materials into high-quality biochar using the HTC process. Experiments are being conducted to investigate the effects of specific waste properties on the carbonization process and to determine material and energy balances.
Juvenile giant grouper at the AWI Bremerhaven. Photo: Mirko Bögner
European samphire: a representative of salt-tolerant plants. Photo: Mirko Bögner
Not every type of burnt material is equally suitable for use as fertilizer! However, those who carefully select the raw materials for burning and also ensure that they are used appropriately will benefit from a natural supply of nutrients and lush growth. Photo: Gerald Dunst
Die Hydrothermale Karbonisierung (HTC-Verfahren, etwa: „wässrige Verkohlung bei erhöhter Temperatur“), das Produkt auch als Hydrokohle bezeichnet, ist ein chemisches Verfahren zur einfachen Herstellung von Braunkohle-Substitut, Synthesegas, flüssigen Erdöl-Vorstufen und Humus aus Biomasse unter Freisetzung von Energie und Wasser. Der Prozess, der die in der Natur in 50.000 bis 50 Millionen Jahren ablaufende Braunkohle-Entstehung („Inkohlung“) innerhalb weniger Stunden technisch nachahmt, wurde von Friedrich Bergius erforscht und erstmals im Jahre 1913 beschrieben.
To the Wikipedia article on hydrothermal carbonationAquakultur oder Aquafarming ist die kontrollierte Aufzucht von aquatischen, also im Wasser lebenden Organismen, insbesondere Fischen, Muscheln, Krebsen und Algen. Allen in Aquakultur produzierten Organismen gemein ist die Zuordnung zu einem Besitzer. So unterscheidet sich die Aquakultur vom klassischen Fischfang in öffentlichen Gewässern. In den letzten Jahrzehnten haben Nahrungsmittel aus Aquakultur, unter anderem wegen der Überfischung von Wildbeständen, zunehmend an Bedeutung gewonnen. Nach Angaben der Ernährungs- und Landwirtschaftsorganisation der Vereinten Nationen lag der weltweite Jahresertrag im Jahr 2020 bei über 122,6 Mio. t. In Aquakulturen wurden 2020 insgesamt 57,5 Mio. t Fisch, ca. 18 Mio. t Weichtiere, rund 11 Mio. t Krebstiere sowie etwa 35 Mio. t Algen und weitere Wasserorganismen produziert. Die weltweiten Hauptaktivitäten im Bereich der Aquakultur lassen sich in drei Bereiche untergliedern: Fisch-, Muschel-, Garnelenzucht und anderes (Mast) für die Nahrungsmittelindustrie, z. B. Austernzucht Mikro- und Makroalgenzucht für die chemische, pharmazeutische und lebensmitteltechnische Industrie sowie den Futtermittelmarkt Setzlingszucht für die Fischzucht, zur Arterhaltung…
To the Wikipedia section on recirculating aquaculture systems (RAS)
Can aquaculture function completely without residues? The OptiRAS project has developed an approach. In a concept unique throughout Germany, process water was used for hydroponics, and residues from marine fish farming systems were carbonized. Several production levels including their residues were connected to form a well-thought-out circular system, with surprisingly versatile results.
At the center of the project: the warm-water fish species Giant Grouper, salt-tolerant plants such as samphire and saltwort for utilizing dissolved nutrients from fish farming, and a process to transform all solid materials arising in aquaculture into valuable biochar.
Economically farming new fish species: The giant grouper (Epinephelus lanceolatus) is considered a delicacy in Asia. In Germany, it has now been tested for the first time in a marine recirculating aquaculture system (RAS), with success. The animals grew excellently under different stocking densities without signs of stress, showed good health values and can be well fed with EU-approved feed.
Cultivating plants in saltwater: In a specially developed aeroponic system, samphire, saltwort and buck’s-horn plantain were cultivated. The result: Some plants even thrive better in saline aquaculture water than with normal fertilizer, a sustainable addition to fish farming.
Utilizing residues instead of disposing of them: Instead of disposing of excretions and feed residues from fish farming, they were converted into biochar in the project through hydrothermal carbonization (HTC). This biochar can be used for fertilization, for compost soil (“Terra Preta Shrimp”) or for thermal utilization.
The OptiRAS system is more than an aquaculture, it is a modular building-block system that combines animal farming, plant production and residue utilization. Particularly innovative is the aeroponic plant module, which can be operated stacked on top of each other in buildings and is therefore extremely space-saving. The plants grow there on a mist basis, without soil, but with precisely adjusted nutrients from the fish water.
The combination with plants increases the utilization of resources, and the biochar even creates a new product for the horticulture or energy sector.
OptiRAS provides a coherent concept for the marine aquaculture of the future: no wastewater, no fertilizer from outside, no residues, instead a clever coupling of biological processes. The pilot plants will remain in use even after the end of the project in order to further optimize the system.
Project coordination: Mirko Bögner, Alfred Wegener Institute (AWI)
