CIRCULAR AQUACULTURE: A SUSTAINABLE MODEL FOR ROTIFER PRODUCTION WITH MICROALGAE AND WASTEWATER UTILIZATION

Abstract

Rotifers (Brachionus plicatilis) are essential live feed organisms in marine fish hatcheries. However, rotifer production raises sustainability concerns because it depends highly on costly imported commercial feeds and generates large volumes of wastewater that is rich in nutrients. To address these two challenges, this study developed a sustainable aquaculture model in which rotifer wastewater (RWW) is utilized as a growth medium for microalgae. The wastewater-grown microalgae are then used as a feed source for rotifers. Five microalgae species and a commercial feed were initially screened to identify the most efficient species in producing rotifers. The five microalgae were Nannochloropsis sp. (NS), Dunaliella salina (DS), Porphyridium sp. (PC), Tetraselmis sp. (TS), and Phaeodactylum tricornutum (PT). DS produced the highest rotifer density (485 ± 112 individuals/mL), followed by PC (419 ± 52 individuals/mL) and NS (390 ± 48 individuals/mL), while commercial feed produced 197 ± 33 individuals/mL. The species, NS, DS, and PC, were then cultivated in RWW, resulting in nitrogen removal efficiencies of 74.31%, 49.31%, and 85.67%, respectively. NS produced the highest biomass (0.929 g/L), and its nutritional profile increased significantly when cultivated in RWW (lipid content from 23.25% to 34.41% and total fatty acids from 884.58 ppm to 2855.30 ppm). Finally, wastewater-grown NS produced significantly higher rotifer populations (1096 individuals/mL) than commercial feed (323 individuals/mL). The study concluded that the proposed rotifer production model can effectively treat wastewater, enhance microalgae nutritional profile, increase rotifer production, and reduce reliance on imported commercial feeds.