Pilot 1 - TARAS (University of Gdańsk)
The production of white leg shrimp in most parts of Europe relies on land-based recirculating aquaculture systems (RAS). Although these systems substantially reduce water consumption, they do not fully comply with the principles of a circular economy, as regular partial water exchange is required, particularly at high stocking densities, to maintain suitable water quality conditions.
To minimize water exchange and provide an alternative treatment strategy for nutrient-rich process water, the TARAS project investigated the cultivation of Baltic microalgae in RAS effluents. The aim was to recover excess nutrients and convert them into lipid-rich biomass, which could potentially be recycled as shrimp feed or utilized in other value-added applications.
The results were promising, as all investigated strains were able to grow in RAS process water and efficiently remove nutrients. Nitrate and phosphate concentrations were reduced by up to 85 % and 80 %, respectively. However, further optimization of the process water composition, particularly regarding the N:P ratio and the concentrations of silica and iron, appears necessary to maximize nutrient removal efficiency.
Since nutrient removal performance was comparable among the investigated strains, strain selection should primarily be guided by ecophysiological and biochemical characteristics that enable the production of high-quality biomass with commercial value. Future studies should also explore the potential of mixed microalgal cultures and evaluate the feasibility of using unfiltered or raw process water to further improve the sustainability and resource efficiency of RAS-based shrimp production.