Cultivating Marine Microalgae Nannochloropsis oculata and Chaetoceros muelleri in Shrimp Farming Effluent: Growth and Nutrient Removal for Sustainable Aquaculture

Abstract

Shrimp farming effluents (SFEs) are rich in nitrate and phosphate, posing significant eutrophication risks to receiving water bodies if discharged untreated, necessitating sustainable bioremediation strategies. Although microalgae‐based treatment has been explored, limited research has systematically compared the performance of different species under varying dilution ratios and initial cell densities specifically for shrimp effluent. This study assessed the cultivation performance and nutrient removal efficiency of Nannochloropsis oculata and Chaetoceros muelleri for bioremediation of SFE, focusing on nitrate and phosphate removal. Experiments evaluated nutrient dynamics and algal growth across SFE dilutions (0%–50%) and initial cell densities (C. muelleri: 35 × 104 and 70 × 104 cells/mL; N. oculata: 200 × 104 and 400 × 104 cells/mL). Both species demonstrated effective nutrient removal, with higher removal efficiencies observed at lower initial densities. Under optimal 25% SFE conditions, N. oculata achieved 97% nitrate and 95% phosphate removal within 12 days, while C. muelleri reached 81% nitrate and 94% phosphate removal within 6 days. Specific growth rates surpassed controls, yielding maximum biomasses of 2425 × 104 (N. oculata, 12 days) and 595 × 104 cells/mL (C. muelleri, 10 days). The novelty of this study lies in the systematic optimization of operational parameters and identification of species‐specific advantages for tailored bioremediation. These findings highlight the robustness of both microalgae across SFE gradients and support their application in sustainable aquaculture wastewater treatment, nutrient recycling, and biomass valorization. Future studies should focus on pilot‐scale validation, long‐term stability assessment, and comprehensive biomass characterization for downstream applications.