Potentially commercialisable alga, Coelastrella sp. SDEC-28, for stable growth and multiple product applications in pilot-scale seawater-wastewater cultivation

The use of seawater for low-cost cultivation of freshwater microalgae faces limitations because hyperosmotic environments restrict microalgal growth and reduce metabolite accumulation. This study applied monosodium glutamate wastewater to seawater cultivation (SMGW) for the high-value microalgal strain Coelastrella sp. SDEC-28. With the assistance of aeration, biomass and lipids productivity increased twofold, reaching values of 188.95 and 63.24 mg/L/d in SMGW. The special structure of Coelastrella contributed to the stability of its intracellular environment. Thus, three metabolites—carbohydrates, lipids, and proteins—remained stable in the seawater medium at 28.31%, 36.59%, and 30.52%, respectively. The fatty acids and amino acids profiles highlighted potential for producing biodiesel and health supplements. Finally, the establishment of the first 1000-L microalgal cultivation system for SDEC-28 demonstrated the feasibility of large-scale commercial production. This study highlights SMGW with aeration as a cost-effective strategy for boosting SDEC-28's biomass and lipids yields while stabilizing metabolites and enabling scalable production through a 1000-L cultivation system.