## 3 Results
### Final Characteristics of the Obtained CTs  
#### 3.3.1 Chemical Features of the Final CTs and Their Dilutions  
The chemical characteristics of the final CTs are reported in Table 4. With respect to the pH values, Wh-CTs could be classified as acid to sub-acid. The pH of the remaining CTs showed an alkaline reaction. EC of the final CTs ranged from 4.45 to 8.20 mS cm\({}^{-1}\), resulting particularly high and not suitable for a direct agronomical application of CTs. SAR, as a salinity index, ranged from a minimum of 2.4, measured for CT-Wh2, to 8.1 for CT-M3 (Table 4). In all CTs, total N content showed an increasing trend with respect to the concentration measured in CT-Wa. Such increases were proportional to the applied doses of additives. Total N concentrations ranged from 97 mg L\({}^{-1}\) measured in CT-Wa to 288 mg L\({}^{-1}\) found in CT-M3 (Table 4). On average, N-NH\({}_{4}\)\({}^{+}\) represented 22  
A general increase in the metals concentration was observed in all CTs with additives compared to the CT obtained only with water addition (Table 4). Such evidence was confirmed by the enrichment factors of the CTs, calculated as the ratio between the heavy metal concentration in CT and the concentration in the corresponding extracting solution (Table 5). Such findings underline the high extractive capacity of metals from the compost. Figure 2 shows pH and EC values measured in the CT diluted with tap water. The CIs seemed well buffered at all the dilutions examined. All the extracts at dilution ratio 1:4 (CT to water) showed EC ranging from 1 and 2 mS cm\({}^{-1}\). Such EC values are opportune for agronomical purposes (CT distribution by means of an irrigation system). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Parameter** & **CT-Wa** & **CT-Wh1** & **CT-Wh2** & **CT-M1** & **CT-M2** & **CT-M3** & **Limits Imposed by the Italian Law** \\ \hline pH & U pH & 8.60 & 5.00 & 6.02 & 8.72 & 8.77 & 8.99 & - \\ EC & mS cm\({}^{-1}\) & 4.45 & 6.87 & 8.20 & 5.82 & 6.03 & 7.45 & - \\ SAR & & 3.6 & 3.4 & 2.4 & 5.6 & 7.1 & 8.1 & - \\ Total-N & mg L\({}^{-1}\) & 97 & 138 & 197 & 151 & 194 & 288 & - \\ N-NH\({}_{4}\)\({}^{+}\)/ & \({}^{\prime\prime}\) & 24 & 21 & 50 & 39 & 47 & 50 & - \\ N-NH\({}_{4}\)\({}^{+}\)/Total-N & & 0.25 & 0.15 & 0.25 & 0.26 & 0.24 & 0.17 & - \\ TOC & g L\({}^{-1}\) & 1.53 & 2.18 & 2.89 & 1.97 & 1.61 & 1.76 & - \\ HA + FA & g L\({}^{-1}\) & 0.03 & 0.52 & 0.66 & 0.25 & 0.41 & 0.53 & - \\ Ca & mg L\({}^{-1}\) & 51 & 226 & 416 & 59 & 59 & 74 & - \\ Mg & \({}^{\prime\prime}\) & 12 & 33 & 60 & 14 & 16 & 17 & - \\ K & \({}^{\prime\prime}\) & 373 & 545 & 731 & 524 & 567 & 615 & - \\ Na & \({}^{\prime\prime}\) & 103 & 199 & 187 & 170 & 218 & 275 & - \\ Fe & \({}^{\prime\prime}\) & 1.86 & 1.6 & 3.37 & 2.62 & 2.19 & 2.43 & 2.0 \\ Cu & \({}^{\prime\prime}\) & 0.20 & 0.15 & 1.16 & 0.23 & 0.25 & 0.20 & 1.0 \\ Zn & \({}^{\prime\prime}\) & 0.32 & 0.37 & 0.43 & 0.53 & 0.44 & 0.45 & 0.5 \\ Mn & \({}^{\prime\prime}\) & 0.18 & 1.07 & 1.91 & 0.30 & 0.28 & 0.28 & 0.2 \\ Cr & \({}^{\prime\prime}\) & 0.244 & 0.029 & 0.034 & 0.027 & 0.021 & 0.045 & 0.1 \\ Cd & \({}^{\prime\prime}\) & 0.000 & 0.004 & 0.001 & 0.002 & 0.000 & 0.000 & 0.005 \\ Ni & \({}^{\prime\prime}\) & 0.037 & 0.029 & 0.054 & 0.064 & 0.071 & 0.105 & 0.2 \\ Pb & \({}^{\prime\prime}\) & 0.04 & 0.05 & 0.07 & 0.05 & 0.06 & 0.05 & 0.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Chemical and physical features of the final CTs and concentration limits of total heavy metals imposed by the Italian law for wastewater reuse (Decree No. 185, 12/06/2003, Ministry for Environment). \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c} \hline \hline
**Metal** & **A\({}_{1}\)** & **A\({}_{2}\)** & **A\({}_{3}\)** & **A\({}_{4}\)** & **A\({}_{5}\)** & **A\({}_{6}\)** & **B\({}_{1}\)** & **B\({}_{2}\)** & **B\({}_{2}\)** & **B\({}_{4}\)** & **B\({}_  
Additives significantly influenced the assessed community levels of physiological profiles (Table 7).