## 3 Results
### Overall CW WWTP Functioning and Performance
\begin{table}
\begin{tabular}{c c c c c c c c} \hline  & & **IN** & **OUT FRB** & **OUT HF 1** & **OUT HF 2** & **OUT FWS** & **OUT Fin** \\ \hline pH & Mean & 6.8 & 7.7 & 7.9 & 7.9 & 8.0 & 8.1 \\  & Std. dev. & 0.6 & 0.3 & 0.2 & 0.2 & 0.2 & 0.2 \\  & Min & 5.2 & 7.3 & 7.5 & 7.6 & 7.6 & 7.7 \\  & Max & 8.2 & 8.5 & 8.3 & 8.3 & 8.5 & 8.6 \\  & 80\({}^{\circ}\) perc. & 7.3 & 7.9 & 8.0 & 8.0 & 8.2 & 8.3 \\  & No. of s. & 29 & 29 & 28 & 28 & 29 & 38 \\ \cline{2-7}  & Discharge limit & & & & & 5.5–9.5 \\ \hline COD & Mean & 1159 & 345 & 84.0 & 105.9 & 57.1 & 29.0 \\ \([\)mg L\({}^{-1}]\) & Std. dev. & 432 & 273 & 66.1 & 83.0 & 45.4 & 19.2 \\  & Min & 166 & 30 & 34.6 & 34.5 & 20.5 & 8.9 \\  & Max & 1930 & 948 & 387.0 & 347.0 & 249.0 & 114.0 \\  & 80\({}^{\circ}\) perc. & 1530 & 509 & 94.3 & 143.0 & 70.8 & 37.9 \\  & No. of s. & 29 & 29 & 28 & 28 & 29 & 37 \\ \cline{2-7}  & Discharge limit & & & & & 160 \\ \hline N-NO2- & Mean & 0.24 & 0.05 & 0.06 & 0.05 & 0.03 & 0.04 \\ \([\)mg L\({}^{-1}]\) & Std. dev. & 0.63 & 0.02 & 0.03 & 0.02 & 0.02 & 0.06 \\  & Min & 0.03 & 0.01 & 0.02 & 0.02 & 0.01 & 0.00 \\  & Max & 3.50 & 0.09 & 0.10 & 0.10 & 0.09 & 0.35 \\  & 80\({}^{\circ}\) perc. & 0.16 & 0.07 & 0.08 & 0.07 & 0.04 & 0.04 \\  & No. of s. & 29 & 29 & 28 & 28 & 29 & 38 \\ \cline{2-7}  & Discharge limit & & & & & 20 \\ \hline TP & Mean & 7.2 & 7.5 & 6.4 & 6.7 & 5.6 & 3.9 \\ \([\)mg L\({}^{-1}]\) & Std. dev. & 5.6 & 3.8 & 2.6 & 2.9 & 2.5 & 2.1 \\  & Min & 1.4 & 2.4 & 2.5 & 2.8 & 2.0 & 0.9 \\  & Max & 19.1 & 16.0 & 10.5 & 12.1 & 11.2 & 8.6 \\  & 80\({}^{\circ}\) perc. & 12.1 & 11.0 & 9.4 & 10.0 & 8.6 & 5.2 \\  & No. of s. & 29 & 29 & 28 & 28 & 29 & 38 \\ \cline{2-7}  & Discharge limit & & & & & 10 \\ \hline MBAS & Mean & 3.0 & 0.8 & 0.5 & 0.5 & 0.4 & 0.2 \\ \([\)mg L\({}^{-1}]\) & Std. dev. & 0.7 & 0.5 & 0.2 & 0.3 & 0.3 & 0.1 \\  & Min & 0.9 & 0.2 & 0.2 & 0.1 & 0.1 & 0.1 \\  & Max & 4.5 & 2.0 & 1.3 & 1.4 & 1.4 & 0.6 \\  & 80\({}^{\circ}\) perc. & 3.5 & 1.3 & 0.7 & 0.8 & 0.5 & 0.3 \\  & No. of s. & 29 & 29 & 28 & 28 & 29 & 38 \\ \cline{2-7}  & Discharge limit & & & & & 2 * \\ \hline \end{tabular} \({}^{*}\) Expressed in terms of total surfactants.  
\end{table} 
Table 2: Statistical analysis of pollutant concentrations of wastewater treated by the CW of Cecchi winery at the different stages of the CW of Cecchi winery: influent (IN); effluent from the 1 st stage FRB beds (OUT FRB); effluent from the 2 nd stage refurbished HF bed (out HF 1); effluent from the 2 nd stage HF beds built during the 2009 upgrade (OUT HF 2); effluent from the 3 rd stage FWS bed (OUT FWS); effluent from the official effluent sampling point, after the optional sand filter (OUT fin). Data from 19 January 2017 to 14 June 2019. Despite that statistically significant differences are evident only from IN to OUT, the pH Box-Whisker plot suggests a constant basification of treated wastewater among the different stages. The mean influent pH passes from an influent value of 6.8 to 8.1 in the effluent (mean values). By the way, the effluent pH never exceeded the limit value for discharge (9.5). The role of the different stages is less evident in terms of total phosphorous. Indeed, a statistically significant difference is registered only for the whole CW WWTP, as visible in Figure 3 and Table 3. On the other hand, the whole system successfully worked as a buffer and a sink of TP, helping to respect the limit for discharge. Although the mean influent TP concentration (7.2 mg L\({}^{-1}\)) is already below the limit value (10 mg L\({}^{-1}\)), the influent TP concentrations are showing several peaks above this value (up to a maximum measured value of 19.1 mg L\({}^{-1}\)), leading the CW WWTP to be fundamental to respect the Italian legislation for discharge. Other monitored nutrient pollutants, i.e., N-NO2- and N-NO3-, resulted less problematic, since their influent values were always below the target values (0.6 mg L\({}^{-1}\) and 20 mg L\({}^{-1}\), respectively).