# Effects of Caprolactam Wastewater on Algal Growth and Nutrients Removal by _Arthrospira platensis_
## 3 Results and Discussion
### Fed-Batch Supply of WCP Decreasing the Impact on A. platensis
#### 3.3.3 Effect of WCP Supply Modes on Biochemical Composition of _A. platensis_
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Culture Time** &
\begin{tabular}{c} **WCP Supplying** \\ **Modes** \\ \end{tabular} & **Chl-a (mg/g)** & **Carotenoid (mg/g)** & **PC (mg/g)** & **APC (mg/g)** & **T-PC (mg/g)** \\ \hline \multirow{4}{*}{Day 4} & Control & 17.37 \(\pm\) 0.29 a & 4.29 \(\pm\) 0.03 b & 112.53 \(\pm\) 1.19 a & 47.26 \(\pm\) 1.12 a & 159.79 \(\pm\) 1.40 a \\  & Fed-batch Mode 1 & 15.06 \(\pm\) 0.48 b & 4.08 \(\pm\) 0.17 b & 99.07 \(\pm\) 1.25 b & 42.98 \(\pm\) 1.6 b & 142.05 \(\pm\) 2.81 b \\  & Fed-batch Mode 2 & 14.66 \(\pm\) 0.36 b & 4.22 \(\pm\) 0.13 b & 98.32 \(\pm\) 2.43 b & 44.06 \(\pm\) 0.66 b & 142.38 \(\pm\) 2.42 b \\  & Batch mode & 9.33 \(\pm\) 0.29 c & 4.58 \(\pm\) 0.15 a & 54.63 \(\pm\) 1.85 c & 34.06 \(\pm\) 1.64 c & 88.69 \(\pm\) 3.34 c \\ \hline \multirow{4}{*}{Day 8} & Control & 19.12 \(\pm\) 0.29 a & 4.78 \(\pm\) 0.14 c & 131.99 \(\pm\) 2.04 a & 50.44 \(\pm\) 1.30 a & 182.43 \(\pm\) 3.34 a \\  & Fed-batch Mode 1 & 16.38 \(\pm\) 0.45 b & 5.11 \(\pm\) 0.09 b & 98.01 \(\pm\) 2.30 b & 44.77 \(\pm\) 0.81 b & 142.78 \(\pm\) 3.02 b \\  & Fed-batch Mode 2 & 15.86 \(\pm\) 0.29 c & 5.20 \(\pm\) 0.16 d & 89.98 \(\pm\) 3.21 c & 43.80 \(\pm\) 1.02 b & 133.78 \(\pm\) 4.23 c \\  & Batch mode & 12.59 \(\pm\) 0.11 d & 5.38 \(\pm\) 0.15 a & 69.52 \(\pm\) 1.67 d & 39.92 \(\pm\) 0.51 c & 109.45 \(\pm\) 1.64 d \\ \hline \multirow{4}{*}{Day 12} & Control & 18.65 \(\pm\) 1.09 a & 4.83 \(\pm\) 0.18 ab & 131.78 \(\pm\) 8.08 a & 56.90 \(\pm\) 6.86 a & 188.68 \(\pm\) 14.39 a \\  & Fed-batch Mode 1 & 13.74 \(\pm\) 0.17 b & 5.04 \(\pm\) 0.06 a & 81.78 \(\pm\) 3.27 b & 47.52 \(\pm\) 3.75 b & 129.29 \(\pm\) 5.72 b \\ \cline{1-1}  & Fed-batch Mode 2 & 12.67 \(\pm\) 0.47 c & 4.88 \(\pm\) 0.19 ab & 73.93 \(\pm\) 3.82 bc & 45.86 \(\pm\) 1.90 b & 119.78 \(\pm\) 5.52 bc \\ \cline{1-1}  & Batch mode & 12.12 \(\pm\) 0.48 c & 4.75 \(\pm\) 0.07 c & 67.76 \(\pm\) 5.83 c & 42.17 \(\pm\) 2.82 b & 109.93 \(\pm\) 8.66 c \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Photosynthesis pigments content of _Arthospira platensis_ as affected by caprolactam wastewater supply modes. Data with different letters indicate significant differences (\(p<\) 0.05) between the control and treatments. content of 40.65% in 25.0% (\(v/v\)) wastewater from a monosodium glutamate factory [37]. _Arthrospira platensis_ had a protein content of 38.13% in olive oil mill wastewater in the presence of excess nutrients [43]. _Spirulina platensis_ was found to contain a protein content of 46.02% in municipal wastewater [44]. In contrast, the batch mode significantly increased the carbohydrate content of _A. platensis._ The carbohydrate content in fed-batch mode 1 was 18.80%, 15.02%, 16.65%, and 13.51% on days 4, 8, 12, and 16, respectively, and the carbohydrate content in fed-batch mode 2 was almost the same as that in fed-batch mode 1. The carbohydrate content in the batch mode was 30.37%, 22.94%, and 20.22% on days 4, 8, and 12, respectively, which was significantly higher than that of fed-batch mode 1. The total lipid content was not affected by the WCP supply modes, and remained stable during the 16 d of cultivation. A similar result was reported in a study by [PERSON] et al. (2015), in which the carbohydrate content increased from 3.29% to 17.69% as the wastewater concentration increased from 0.00% to 50.00%, but the wastewater had little influence on the total lipid content [37]. Table 5 shows the protein and total phycobiliprotein (T-PC) production of _A. platensis_ affected by the WCP supply modes. The total yields of protein and T-PC of fed-batch mode 1 were 3573.38 mg/L and 745.49 mg/L, respectively. Although these yields were lower than those of the control, they were significantly higher than those of fed-batch mode 2 and the batch mode (\(p<0.05\)). These results implied the advantage of fed-batch mode 1 in wastewater supply in WCP denitrification. Considering all the results of the effects of the WCP supply modes on the growth, photosynthesis pigments, and biochemical composition of _A.