## 3 Results and Discussion
### Carbon and Nitrogen Removal Study
#### 3.1.1 Cod  
The influent concentrations of COD varied throughout the study, but they were generally between 5000-6000 mg/L. Phase 1 had an average influent concentration of 6189 mg/L, Phase 2 was 4997 mg/L, and Phase 3 was 5851 mg/L. Despite the varying influent concentrations, 90% of all effluent samples were below 50 mg/L, and 33% were below the detection limit of 20 mg/L. Across all of the treatment systems and phases, over 90% of the total COD removal occurred in the first column. No significant differences in COD removal were observed between the control system and the treatment systems with the nitrogen adsorption media (\(p>0.05\)). The high level of treatment that was observed throughout the study was consistent with the performance of other configurations of vertical flow constructed wetlands for the treatment of winery wastewater and previous applications of this system in treating milling facility wastewater. In a 2011 study by [PERSON] et al. (2011) [PERSON] et al. (2011), the vertical flow stage of a hybrid constructed wetland was shown to remove up to 70% COD from winery wastewater. The influent concentrations to the vertical flow stage ranged from 422 to 2,178 mg/L COD and surface loading rates to this stage ranged from \(4.3\times 10^{-2}\) to 4.66 kg COD/m\({}^{2}\)/d (\(8.78\times 10^{-3}\) to \(9.5\times 10^{-2}\) lb COD/ft\({}^{2}\)/d) [PERSON] et al. (2016) [PERSON] et al. (2016) monitored six years of performance data from a similar system treating winery wastewater that was mixed with domestic wastewater in the cold-weather climate of Ontario, Canada. The system had four subsurface treatment cells that contained a gravel-and-sand mixture with the third cell saturated and containing wood chips to facilitate denitrification. This system had a surface loading rate of \(3.4\times 10^{-2}\) kg COD/m\({}^{2}\)/d (\(6.96\times 10^{-3}\) lb COD/ft\({}^{2}\)/d) and treated an average influent concentration of 3043 mg/L COD during the six warmest months of the year and 2117 mg/L COD during the six coolest months of the year. This system consistently removed an average of 99% COD [PERSON] and [PERSON] (2015) [PERSON] and [PERSON] (2015) observed 96% COD removal while using an SVFCW to treat milking facility wastewater with an average influent concentration of 736 mg/L COD. Although the influent concentration was lower than that used in this study, the treatment systems were sized while using the same surface loading rate of 5.18e-2 kg COD/m\({}^{2}\)/d (\(1.06\times 10^{-2}\) lb COD/ft\({}^{2}\)/d) [PERSON] and [PERSON] (2015). This surface loading rate is the greatest of the discussed systems, which indicated the smallest land area needed for maintaining high treatment efficiency. A review of biological treatment systems for winery wastewater found that COD removal efficiencies are generally within 90-95% of total COD due to the recalcitrant soluble fraction of COD that cannot be biologically or physically removed [PERSON] et al. (2016). Biological removal is a main method of COD removal in constructed wetlands [PERSON] et al. (2016). Treatment systems are commonly inoculated before operation to decrease the start-up time of the microbial populations [PERSON] et al. (2016); [PERSON] et al. (2016), as was done in this study. Even with inoculation, a start-up period of approximately 13 days was required for each treatment system to reach \(>\)90% removal efficiency. The first column of the systems was operated without prior inoculation to investigate the role of inoculation in the start-up period. Figure 4 illustrates the COD removal efficiency over time for columns that were inoculated and those that were not inoculated before operation. The removal efficiency was higher than in the columns that were not inoculated in the first 13 days of the start-up period for the inoculated columns. However, by the thirteenth day, both sets of columns had reached \(>\)90% COD removal efficiencies.