Sustainable nutrient recovery process in brackish aquaculture effluent with microalgae technology

The rapid expansion of the aquaculture industry has led to the generation of large volumes of nutrient-rich wastewater, posing significant environmental risks if not properly managed. This study investigates Parachlorella kessleri for treating brackish effluent within a ‘Circular Economy’ framework. Cultivation was tested in 2 L batch and 8 L semi-continuous reactors under various nutrient supplementations. Maximum batch productivity (91.72 mgSS·L −1 ·d −1 ) required phosphorus and micronutrients addition, achieving nutrient removal below the permitted limit. In semi-continuous operation productivity reached 50.55 mgSS·L −1 ·d −1 . Results indicate that unsupplemented batch operation maximises lipid content, while supplemented semi-continuous operation favors carbohydrate and protein enrichment. These findings demonstrate a scalable pathway for integrating microalgae into industrial aquaculture, providing reclaimed water for reuse and high-value biomass for sustainable feed or biofuels. This approach closes the nutrient loop, enhancing resource efficiency in the industry.