## 4 Conclusions  
This study showed the feasibility of using _C. vulgaris_ for the bioremediation of a paper industry effluent fortified with a nitrogen source, targeting phosphorus removal. _C. vulgaris_ was able to grow in all studied effluent conditions (in non-diluted and diluted ones). However, it was possible to conclude that growing on non-diluted effluent resulted in lower biomass productivities, which was also reflected in nitrogen and phosphorus removal efficiencies. From microalgal growth and nitrogen removal points of view, the effluent dilutions used in assays 3 and 4 (intermediate dilutions) seem to be the most adequate, as microalgal growth was not inhibited in these conditions and nitrogen mass removal was quite satisfactory, achieving final concentrations of (7.1 \(\pm\) 0.7) mg\({}_{\rm N}\) L\({}^{-1}\) and (2.81 \(\pm\) 0.05) mg\({}_{\rm N}\) L\({}^{-1}\), respectively. Regarding phosphorus removal, concentrations achieved in the last day of culturing in assays 3 and 4 were higher ((4.63 \(\pm\) 0.04) mg\({}_{\rm P}\) L\({}^{-1}\) and (2.940 \(\pm\) 0.005) mg\({}_{\rm P}\) L\({}^{-1}\), respectively) than the one obtained in assay 5 ((1.85 \(\pm\) 0.02) mg\({}_{\rm P}\) L\({}^{-1}\)). However, the results obtained in assay 5 suggest a growth limitation, mainly related to nitrogen concentration. Accordingly, the obtained results indicate that these \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Effluent** & **Microalgae** & **Culture Time** & **Element / Form** & **Initial** & **\%R** & **RR** & **(mg L\({}^{-1}\)** \\  & & **(d)** & **(mg L\({}^{-1}\))** & **(\%)** & **(\%)** & **(d\({}^{-1}\))** \\ \hline \multirow{6}{*}{Paper} & \multirow{6}{*}{_C. vulgaris_} & \multirow{6}{*}{\(11\)} & (NO\({}_{3}\)+NO\({}_{2}\))-N & 34.2 & 24 & 0.75 & \multirow{6}{*}{This study} \\  & & & PO\({}_{4}\)-P & 12.3 & 13 & 0.14 & \\ \cline{1-1}  & & & (NO\({}_{3}\)+NO\({}_{2}\))-N & 28.2 & 43 & 1.1 & \\ \cline{1-1}  & & & PO\({}_{4}\)-P & 8.55 & 17 & 0.13 & \\ \cline{1-1}  & & & (NO\({}_{3}\)+NO\({}_{2}\))-N & 21.5 & 67 & 1.3 & \\ \cline{1-1}  & & & PO\({}_{4}\)-P & 6.04 & 23 & 0.13 & \\ \cline{1-1}  & & & (NO\({}_{3}\)+NO\({}_{2}\))-N & 16.7 & 83 & 1.3 & \\ \cline{1-1}  & & & PO\({}_{4}\)-P & 4.22 & 30 & 0.12 & \\ \cline{1-1}  & & & (NO\({}_{3}\)+NO\({}_{2}\))-N & 12.7 & 80 & 0.93 & \\ \cline{1-1}  & & & PO\({}_{4}\)-P & 4.01 & 54 & 0.20 & \\ \hline Pulp and & \multirow{6}{*}{_C. vulgaris_} & \multirow{6}{*}{14} & NH\({}_{4}\)-N & 240 & 99 & 17 & \multirow{6}{*}{[19]} \\  & & & PO\({}_{4}\)-P & 8.00 & 97 & 0.55 & \\ \cline{1-1}  & & & & NH\({}_{4}\)-N & 22.4 & 99 & 3.7 & \\ \cline{1-1}  & & & NO\({}_{3}\)-N & 1.06 & 27–53 & 0.048–0.094 & \\ \cline{1-1}  & & & PO\({}_{4}\)-P & 10.1 & 96–98 & 1.6–1.7 & \\ \cline{1-1}  & & & & NH\({}_{4}\)-N & 14.8 & 96–98 & 2.3–2.4 & \\ \cline{1-1}  & & _dimorphus_ & & NO\({}_{3}\)-N & 1.08 & 41–46 & 0.074–0.083 & \\ \cline{1-1}  & & _Selensrum_ & & PO\({}_{4}\)-P & 1.60 & 96–97 & 0.25-0.26 & \\ \cline{1-1}  & & & & NH\({}_{4}\)-N & 21.0 & 99 & 3.5 & \\ \cline{1-1}  & & & NO\({}_{3}\)-N & 1.25 & 27–43 & 0.056–0.090 & \\ \cline{1-1}  & & & PO\({}_{4}\)-P & 2.99 & 90–94 & 0.45–0.47 & \\ \hline Paper mill & \multirow{2}{*}{_Scondesmus_ sp.} & \multirow{2}{*}{28} & NO\({}_{3}\)-N & 2.24 & 65 & 0.052 & \multirow{2}{*}{[1]} \\  & & & PO\({}_{4}\)-P & 9.86 & 71 & 0.25 & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison between nutrients removal efficiencies (%R, in %) and average removal rates (RR, in mg L\({}^{-1}\) d\({}^{-1}\)) obtained in this study and other studies reporting microalgal growth in effluents resulting from pulp and paper industries. values can be further improved by studying different N:P molar ratios, different microalgal cultivation conditions, dilution with other effluents, among others. Improving the remediation performance can significantly contribute to the development of an effective microalgae-based remediation process of pulp and paper industry effluents. Conceptualization, B.P., A.L.G., V.J.PV. and J.C.M.P. ; methodology, B.P., A.L.G.