## 3 Results and Discussion
### Effect of Different Glucose Concentration on Microalgal Growth, Pigments, and Nutrient Removal  
The carbon source concentration significantly impacts microalgal growth rates in mixotrophic cultivation. However, excessive concentrations may inhibit biomass accumulation and lead to substrate inefficiency [55]. Consequently, following the identification of glucose as the optimal carbon source, the effect of varying glucose concentrations (0, 2, 5, 8, 10, 20, 30 g/L) on the biomass growth of FACHB-8 was systematically assessed. ADSW without glucose supplementation (0 g/L) served as the control. As shown in Figure 4, the algal growth was severely inhibited in this control group, with all glucose-supplemented groups exhibiting a higher biomass accumulation than the control after 14 days. Also, enhancing the initial glucose concentration in the ADSW significantly enhanced the biomass growth. During days 0-4, all treatment groups (except the 2 g/L and control groups) showed comparable growth rates. A marked acceleration in biomass accumulation occurred in the 20 g/L group from days 4 to 6, reaching 3.56 g/L by day 6 (Figure 4). This group ultimately achieved the highest biomass production (3.81 g/L) after 14 days of cultivation (Table 4), as compared to 0.58 g/L in the control group. According to Table 4, the 20 g/L group also reached the highest biomass productivity (271.31 mg/L/day) and maximum biomass productivity (1350.00 mg/L/day). [PERSON] et al. [41] reported that culturing _C. vulgaris_ 31 in a modified Bristol medium supplemented with 10 g/L of glucose under mixotrophic cultivation achieved a biomass productivity of 0.226 g/L/day, which is similar to our results. Furthermore, this group showed the highest specific growth rate of 0.42 d\({}^{-1}\) (Table 4). In contrast, as readily seen in Figure 4, the 30 g/L group displayed a suppressed growth (1.92 g/L). This suppression was likely caused by excessive glucose inhibiting cellular respiration, thereby impairing growth, a phenomenon aligning with previous studies [29; 56]. As shown in Figure 5a, chlorophyll \(a\) concentrations in ADSW-supplemented cultures increased compared to the control. Chlorophyll \(a\) levels peaked on day 6 across all glucose treatments, which was followed by stabilization. The 2 g/L glucose group achieved the highest chlorophyll \(a\) accumulation (27.32 mg/L), while the 20 g/L group showed a slightly lower but comparable value (22.85 mg/L). Figure 5b reveals that carotenoid concentrations increased significantly by day 4 in all groups except the 2 g/L and control treatments, mirroring the chlorophyll \(a\) trend. Caroenoid accumulation began on day 4 and stabilized by day 6, indicating a robust algal growth during this period. The 20 g/L glucose group yielded the highest carotenoid concentration (13.57 mg/L) after 14 days of cultivation. These results aligned with the aforementioned growth data, demonstrating the superior growth performance of FACHB-8 in ADSW supplemented with 20 g/L of glucose. As shown in Table 5, intriguingly, the 2 g/L glucose group achieved the highest TN removal rate (92.15%), while the 20 g/L glucose group showed the highest TP removal rate (82.93%). Numerous studies have reported that microalgae-mediated wastewater treatment often achieves removal efficiencies of 60-99% for TN and 50-95% for total phosphorus TP [14; 18; 42]. Notably, TN removal rates remained similar (-85%) across all glucose-supplemented groups except the control and the 2 g/L glucose group (Table 5).