Enhancement of disturbance on oleaginous microalgal growth applying in semi-open photobioreactors: Dynamic response of physiological characteristics, application of wastewater cultivation.

To investigate hydrodynamic effect on microalgal physiological character, the self-designed photobioreactor was used to cultivate microalgae for evaluating bioenergy feasibility. The oleaginous microalgae were chosen as objective, analyzing growth, photosynthesis activity, and lipid accumulation under varying hydrodynamic disturbance. The microalgal biomass accumulation display statistically significant variation across different flow rates (p < 0.05). The best flow rate of 0.1 L/s for promoting microalgae biomass under flow velocity of 0.178 m/s, yielding maximum biomass production of 660.54 mg/L and lipid productivity of 30.02 mg·L·d. Below this threshold velocity of 0.178 m/s, biomass production exhibited a positive correlation with increasing flow rate. The chlorophyll a concentration peaked at 31.90 mg/L, indicating enhanced photosynthetic activity, consistent with maximum quantum yield of Y(II) and electron transport rate of ETR, confirming superior algal growth performance. When cultivated in domestic wastewater for lipid production, the oleaginous microalgae exhibited efficient nutrient utilization, achieving removal efficiencies exceeding 99 % (total nitrogen), 87 % (total phosphorus), and 41 % (total organic carbon). The lipid profiling revealed 204.07 mg/L triacylglycerol production in photobioreactor-cultured strains, representing an 84 % increase over Desmodesmus sp., corroborated by overexpressed enzymes of acetyl-CoA carboxylase and diacylglycerol acyltransferase. The fatty acids performed elevated saturation and monounsaturation levels, demonstrating optimal biodiesel feedstock characteristics.