## 3 Results
### Evolution of the Measured Parameters during the Production Process of CTs  
#### 3.2.1 Electrical Conductivity and pH  
During the extraction process, the temperature of all CTs was around 19 \({}^{\circ}\)C (as the room temperature). EC and pH during the extraction process (0 h, 24 h and 48 h from the start of the process) are reported in Table 3.  
From the start to the end of CTs extraction, pH values showed a slight increasing trend in both CT-Wa and in all the CTs obtained with molasses addition (Table 3). CT-Wh1 and CT-Wh2 pH decreased from 0 to 24 h to then reach values close to the starting ones.  
Marked differences were observed for EC from 0 h to 48 h (Table 3). A more detailed description of the EC pattern is displayed in Figure 1. Particularly, it evolved according an exponential model (sigmoidal) for all the CTs, even if it showed (just after 24 h) growing values according to the following sequence CT-Wh2 \(>\) CT-M3 \(>\) CT-Wh1 \(>\) CT-M2 \(>\) CT-M1 \(>\) TC-Wa. The same sequence was also observed after 48 h (Figure 1).  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Metal**} & \multicolumn{2}{c}{**CT-Wh1**} & \multicolumn{2}{c}{**CT-Wh2**} & \multicolumn{2}{c}{**CT-M1**} & \multicolumn{2}{c}{**CT-M2**} & \multicolumn{2}{c}{**CT-M3**} \\ \cline{2-7}  & \multicolumn{5}{c}{**g Supplied**} \\ \hline Ca & 411 & 685 & 88 & 146 & 292 \\ Mg & 117 & 195 & 32 & 53 & 106 \\ K & 1776 & 2960 & 121 & 201 & 403 \\ Na & 2826 & 4710 & 357 & 595 & 1190 \\ Fe & 0.780 & 1.300 & 0.009 & 0.016 & 0.032 \\ Cu & 0.120 & 0.200 & 0.064 & 0.107 & 0.214 \\ Zn & 0.810 & 1.350 & 0.525 & 0.875 & 1.750 \\ Mn & 0.030 & 0.050 & 0.776 & 1.293 & 2.587 \\ Cr & 0.036 & 0.060 & 0.007 & 0.012 & 0.024 \\ Cd & 0.000 & 0.000 & 0.001 & 0.001 & 0.002 \\ Ni & 0.033 & 0.055 & 0.182 & 0.303 & 0.606 \\ Pb & 0.081 & 0.135 & 0.026 & 0.044 & 0.088 \\ \hline \end{tabular}
\end{table}
Table 2: Amounts of metals added to the CTs by means of the source materials.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**CT**} & \multicolumn{2}{c}{**pH**} & \multicolumn{2}{c}{**EC**} & \multicolumn{2}{c}{**TOC**} & \multicolumn{2}{c}{**(HA + FA)**} & \multicolumn{2}{c}{**[(HA + FA)/TOC] \(\times\) 100**} \\ \cline{2-11}  & \multicolumn{5}{c}{**m5 cm\({}^{-1}\)**} & \multicolumn{2}{c}{**g L\({}^{-1}\)**} & \multicolumn{2}{c}{**g L\({}^{-1}\)**} & \multicolumn{2}{c}{**} \\ \cline{2-11}  & **0 h** & **24 h** & **48 h** & **0 h** & **24 h** & **48 h** & **24 h** & **48 h** & **24 h** & **48 h** \\ \hline CT-Wa & 8.00 & 8.47 & 8.60 & 0.92 & 4.41 & 4.45 & 1.67 & 1.53 & 0.19 & 0.03 & 11.41 & 1.66 \\ CT-Wh1 & 6.46 & 4.90 & 5.00 & 2.18 & 5.92 & 6.87 & 2.14 & 2.18 & 0.30 & 0.52 & 13.99 & 23.91 \\ CT-Wh2 & 6.05 & 4.81 & 6.02 & 2.34 & 6.60 & 8.20 & 2.73 & 2.89 & 0.61 & 0.66 & 22.33 & 22.64 \\ CT-M1 & 8.04 & 8.54 & 8.72 & 2.35 & 5.51 & 5.82 & 2.49 & 1.97 & 0.43 & 0.25 & 17.35 & 12.90 \\ CT-M2 & 8.24 & 8.60 & 8.77 & 2.34 & 5.66 & 6.03 & 2.40 & 1.61 & 0.18 & 0.41 & 7.43 & 25.30 \\ CT-M3 & 8.32 & 8.62 & 8.99 & 4.36 & 7.10 & 7.45 & 2.14 & 1.76 & 0.31 & 0.53 & 14.54 & 30.32 \\ \hline \end{tabular}
\end{table}
Table 3: pH and electrical conductivity (EC) measured in the CTs during the extraction process (at 0 h, after 24 h, after 48 h). Comparison between total organic carbon (TOC, g L\({}^{-1}\)), humic and fulvic acids (HA + FA, g L\({}^{-1}\)), and humic and fulvic acids to TOC ratio [(HA + FA)/TOC] \(\times\) 100, measured after 24 and 48 h from the start of the extraction process.