## 3 Results  
### Overall CW WWTP Functioning and Performance  
The monthly volume discharged by the CW WWTP is represented in Figure 2. Neglecting the evapotranspiration and the precipitation, the effluent volume can be considered a suitable measure to make some consideration on influent hydraulic loads. To this regards, it must be noted that the monthly pattern of effluent discharge can be also affected by the precipitation pattern; therefore, consideration on winery wastewater production based on data exposed in Figure 2 must be taken only as indicative of real influent hydraulic loads faced by the CW WWTP in the monitoring period. Averaging the monthly volume, the daily treated flow was \(60.5\pm 28.3\) m\({}^{3}\) d\({}^{-1}\) during the monitoring period, with the maximum value equal to \(118.4\) m\({}^{3}\) d\({}^{-1}\). Therefore, the CW WWTP worked within the range of hydraulic loads sets in the design phase, which assumed an influent flow rate variable from 70 to 100 m\({}^{3}\) d\({}^{-1}\) function of a different scenario of winery production. As expected, the wastewater production is quite stable among the different months, with a significant monthly variability only in summer months. The results of the statistical analysis on the pollutant parameters are graphically represented by the Box-Whisker plots of Figure 3, while the numerical results are reported in Table 2. Mean removal efficiencies and the results of the \(t\)-tests are resumed in Table 3. The effluent water quality limits were respected for all the monitored pollutants throughout the studied period. This confirms the high overall performance of the CW WWTP. Referring to mean concentrations, the mean removal efficiencies during the monitoring period were 97.5%, 45.5%, 84.7%, 39.9%, and 93.1% for COD, TP, N-NO2-, N-NO3-, and MBAS, respectively, all significantly different according to the \(t\)-test (Table 3). The FRB 1 st stage already provided a very efficient and statistically significant removal of COD (mean removal 70.2%) and MBAS (73.4%), as clearly visible from Figure 3. Statistically significant differences were registered for all the stages in terms of COD and MBAS (see Figure 3 and Table 3). Figure 2: Monthly effluent discharge from the CW of Cecchi winery, monitored from January 2017 to May 2019. This is particularly relevant for the COD parameter; indeed, the high removal efficiencies of the FRB 1 st stage would not be enough to respect the water quality standard (mean COD concentration OUT FRB, 345 mg L\({}^{-1}\)), leading HF 2 nd (mean COD concentration OUT HF, 95 mg L\({}^{-1}\)), and FWS 3 rd (mean COD concentration, OUT FWS 57 mg L\({}^{-1}\)) stages to play a fundamental role in making the CW WWTP effluent suitable for discharge in water body in terms of COD pollutant. The Box-Whisker plot of Figure 3 also evidences the capability of CW to smooth the influent organic load variability, as clear by observing the very high variability of COD concentration in the influent. Figure 3: Box-Whisker plots for pH, COD, N-NO2-, N-NO3-, TP, and anionic surfactants (MBAS) at the different stages of the CW of Cecchi winery: influent (IN); effluent from the 1 st stage French Reed Bed (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 fm). Data from 19 January 2017 to 14 June 2019.