## 3 Results and Discussion  
### Effect of CBZ on the A. brauntii Growth  
The growth of the _A. brauntii_ was followed in both culture media in the absence and in the presence of CBZ to detect whether there would be any effect after the addition of CBZ at both initial inoculum concentrations of \(10^{4}\) and \(10^{5}\) cells/mL. The growth curves (data from the measurements using a Malassez cell) are reported in Figure 1 at the two initial inoculum concentrations. First, all the curves in the figure showed a short latent phase for both media without CBZ of about five days. However, the latent phase was longer when the pollutant was added to both media, at about eight days for both tested inoculum concentrations. This is probably due to the time necessary for the algae to adapt to the presence of the pollutant in the culture media. When comparing growth rates, it was found that the algae in the absence of CBZ had, first, approximately the same growth rates in both media. Discrepancies emerged after 25 days, as growth rates suddenly rose steeply in BB, whereas it followed the same trend with a constant slope in PP. This might be due to the difference in nutritive content, particularly the nitrogen source: proteosepptone of bovine source in PP and EDTA in BB, respectively. As a result, growth was faster in BB than in PP in the absence of CBZ, but the exponential growth phase was shorter, and the death phase started earlier in BB. The consequence is that the maximum amount of algae biomass was higher in PP but was reached far later than in BB. However, it must be pointed out that the amount of algae present was still considerable after 60 days of incubation; due to the delayed maximum, the algae concentration was higher in PP, but the death rate was also higher, while it followed a smooth decreasing shape in BB. The comparison between Figure 1a,b also show that the algae concentrations exhibited exactly the same shape when the inoculum concentration was changed and that, at any time (\(t\)), the algae  
Figure 1: Growth curves of _Ankistrodesmus brauntii_ cultured in Bold’s Basal (BB) and proteosepptone (PP) media at different initial CBZ concentrations (0.0, 2.5, and 10 mg/L, respectively) for an initial inoculum concentration (**a**) \(10^{5}\) cells/mL, (**b**) \(10^{4}\) cells/mL, during 60 days of incubation. concentration was roughly proportional to the inoculum concentration in the absence of CBZ, which means that maximum algae concentrations were observed at the same time, independently from the inoculum concentration without CBZ. Conversely, this pattern changed greatly when CBZ was present in both media in Figure 1. The addition of CBZ shortened the growth phase in both cases. Consequently, the onset of the death phase started earlier, a lower maximum biomass concentration was achieved than without CBZ, and an almost complete death was observed at the end of the 60 days of cultivation. However, differences emerging from the presence of CBZ were media-dependent. For example, the maximum algae concentration was observed in BB, while it was reported in PP without CBZ. The comparison of the results obtained for the cultures with and without CBZ highlighted that the maximum algae concentrations fell due to CBZ in PP, while they were only slightly decreased in BB. A striking result was also that the rapid increase of the algae concentration was forwarded in BB in Figure 1, but with growth rates nearly as high as without CBZ. This differed strongly in PP: although the maximum algae concentration was also forwarded, the values and the growth rate were always smaller than without CBZ. The comparison between Figure 1a,b also highlighted that if the maximum algae concentration was nearly divided by a factor of ten when the inoculum concentration was reduced from \(10^{5}\) to \(10^{4}\) cells/mL (as without CBZ), the time at which this maximum was achieved depended strongly on the inoculum concentration when CBZ was present in both media, which was not observed without CBZ.