2.1. Culture conditions and Materials of FACHB-314
Spirulina FACHB-314 was purchased from Wuhan Institute of Aquatic Plants, Chinese Academy of Sciences. Zarrouk medium (Lebron et al., 2018; Liang et al., 2018) is used as a medium for FACHB-314experiments, composition (g/L: NaHCO3 16.8, NaNO3 2.5, K2SO4 1.00, NaCl 1.00, MgSO4·7H2O 0.20, FeSO4·7H2O 0.01, K2HPO4 0.50, CaCl2·2H2O 0.04, EDTA 0.08, 1mL of trace elements. Among them, trace element composition (g/L): H3BO3 2.86, MnCl2·4H2O 1.81, ZnSO4·4H2O 0.22, NaMoO40.018, CuSO4·5H2O 0.08.
Inoculate FACHB-314 into the reactor and put it in the smart light incubator (Khanra et al., 2018). The structure of the reactor is shown in Scheme 1. The photobioreactor is a 1 L conical flask with a bottom radius of 9 cm and a height of 20 cm. Place the photobioreactor in a smart light incubator, keep the temperature at 25°C, and continuously supply air at a ventilation rate of 0.7 vvm (Karthikeyan et al., 2018a). In an Erlenmeyer flask containing TiO2 and rGO-TiO2, 50 mg of nanomaterials were added for co-cultivation.