## 3 Results and Discussion
### Sequential Batch Photobioreactor Experimentation with Duckweed and microalgae
#### 3.3.2 Tolerance Test of the Microalgae to RW-Based Media Pre-Treated with Duckweed  
The aim of this duckweed pretreatment was not to completely bioremediate the pollutants but to reduce their concentration in each RW% to less inhibitory levels for the microalgae. To test this hypothesis, the supernatants of each pretreatment in PBR-1, coded as TRW-10%, TRW-20%, and TRW-30% (see Section 2.4), were used to cultivate both microalgae in flasks (Figure 6A,B), following the same procedure as described in Section 2.3 with RW%. The results of the two-way ANOVA conducted to examine the effects of factor MEDIUM and factor ALGA on the dependent variables \(\mu_{max}\), \(P_{B}\), and  
Figure 5: Bioremediation effectiveness of raw whey (RW) pollutants by _Lemaa minor_ grown in the 4 L photobioreactor (PBR-1) at an initial surface density of wet biomass of 5.00 g dm\({}^{-2}\) and at the RW% proportions of 10%, 20%, and 30% in the culture medium. Pollutant disappearance kinetics in the culture: (**A**) COD; (**B**) nitrate, NO\({}_{3}\) –; (**C**) phosphate, PO\({}_{4}\)3 –; and (**D**) sulfate, SO\({}_{4}\)2 –. (**E**) Removal efficiency (RE) of pollutants (%). (**F**) Photograph showing part of the effluents pre-treated or clarified by the duckweed culture on the last day of treatment. Columns denoted by different lowercase letters differed significantly in each RW%. Statistical analyses were performed using one-way multivariate analysis of variance (MANOVA). Bars represent standard error. are presented in Figure 6. The analysis revealed a significant main effect of MEDIUM (F (6, 28) = 92.7, \(p\) < 0.001) and ALGA (F (1, 28) = 46.2, \(p\) < 0.001) on the three response variables. Additionally, there was a significant, but weak, interaction effect between both factors (F (6, 28) = 5.7, \(p\) < 0.001). Post hoc comparisons using [PERSON]'s HSD test for MEDIUM showed that \(\mu_{max}\), \(P_{B}\), and \(Y_{B}\) for media pre-treated with duckweed (TRW%) were significantly higher (_p_ < 0.05) than their counterparts (RW%) (Figure 6D,G,J). For factor ALGA, \(\mu_{max}\), \(P_{B}\), and \(Y_{B}\) were also significantly higher for _Chlorella_ than _Scenedesmus_ (_p_ < 0.01) (Figure 6E,H,K) as observed for the RW% in Section 3.2. Further examination of the interaction effect (Figure 6F,J,L) revealed that the relationship between both factors and \(\mu_{max}\), \(P_{B}\), and \(Y_{B}\) varied weakly depending on the level of the factor ALGA. Specifically, \(\mu_{max}\) and \(P_{B}\) (Figure 6F,I) at _Chlorella_ increased more rapidly than _Scenedesmus_ as MEDIUM changed from BG11 to RW-10%; above RW-10%, the trends of the three variables for both microalgae were parallel. These findings suggest that both MEDIUM and ALGA independently influence \(\mu_{max}\), \(P_{B}\), and \(Y_{B}\), while their interaction hardly further modulates the effect on them. The above outcomes anticipated promising results regarding the tolerance of microalgae to raw whey (RW)-based media pre-treated with duckweed. By assessing the growth parameters of microalgae in both treated (TRW%) and untreated (RW%) media, significant improvements in growth performance were observed in TRW% media. Furthermore, the selection of microalgae species significantly influenced their tolerance to RW-based media, with _Chlorella_ demonstrating superior performance compared to _Scenedesmus_. These findings underscore the potential of duckweed pretreatment to improve RW bioremediation and highlight the importance of microalgal species selection in optimizing remediation strategies. This investigation of the tolerance of microalgae to raw whey (RW)-based media pretreated with duckweed anticipated promising results. Assessment of growth parameters in both treated (TRW%) and untreated (RW%) media reveals significant enhancements in growth performance within the TRW% media, suggesting that duckweed pretreatment effectively reduces the inhibitory effects of RW on microalgae growth, leading to improved bioremediation potential.