## 3 Results and Discussion
### Waste Sector Emission by Biogas NH\({}_{3}\) Emission Factor  
In Korea, NH\({}_{3}\) emissions are measured in the waste sector only from other waste treatment such as wastewater treatment. However, this study recognized NH\({}_{3}\) emissions from biogas production facilities, emphasizing the importance of measuring these emissions in the future. As mentioned in the Section 2.3, describing the factors considered for the emission factor, it is difficult to manage NH\({}_{3}\) emissions because it is not based on nitrogen content as is the case in other countries. Waste treatment and biogas production are managed statistically, so the emission factor can be calculated.  
In this study, the results of the improvement of the current domestic air pollutant inventory were applied to the waste sector to check the feasibility of improving the NH\({}_{3}\) inventory and applying NH\({}_{3}\) emission factors for biogas production facilities (Figure 3).  
As a result of applying the NH\({}_{3}\) emission factor based on biogas production, 68 tons/year of NH\({}_{3}\) was found to be emitted. This is approximately three times higher than the existing waste sector NH\({}_{3}\) emissions of 22 tons/year. If the existing NH\({}_{3}\) emissions from the waste sector and the NH\({}_{3}\) emissions from waste based on the emission factor are combined, a total of about 90 tons/year of NH\({}_{3}\) would be emitted. Applying the waste based NH\({}_{3}\) emission factor calculated in this study results in approximately 144 tons of NH\({}_{3}\) emissions per year, which is approximately six times higher than the existing waste sector's annual NH\({}_{3}\) emissions of 22 tons. When combined with NH\({}_{3}\) emissions from the waste sector, the total is 166 tons per year, of which 144 tons are not considered when applying the NH\({}_{3}\) emission factor based on waste and 90 tons when applying the NH  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Site**} & **Mean** & **SD** & **Sampling** \\  & **(kgNH\({}_{3}\)/10\({}^{3}\) Nm\({}^{3}\)-Biogas)** & **(kgNH\({}_{3}\)/10\({}^{3}\) Nm\({}^{3}\)-Biogas)** & **Sampling** \\ \hline A biogas production facility & 0.023 & 0.025 & 31 \\ \hline B biogas production facility & 0.166 & 0.419 & 122 \\ \hline C biogas production facility & 0.192 & 0.263 & 84 \\ \hline Total & 0.150 & 0.334 & 237 \\ \hline \hline \end{tabular}
\end{table}
Table 6: NH\({}_{3}\) emission factor based on biogas production of the investigated biogas production facilities.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{Classification} & \multicolumn{2}{c}{Netherlands National Institute for} \\  & This study & Public Health and the Environment, \\  & (kgNH\({}_{3}\)/Ton-Waste) & Informative Inventory Report, 2020 [22] \\  & & (kgNH\({}_{3}\)/Ton-Waste) \\ \hline NH\({}_{3}\) emission factor & 0.005 & 0.002 \\ \hline \hline \end{tabular}
\end{table}
Table 5: NH\({}_{3}\) emission factor based on the waste of the investigated biogas production facilities.  
emission factor based on biogas production. This again confirms the need to develop emission factors that reflect country-specific characteristics to increase the reliability of the inventory.  
The difference in the application of each unit is judged to be the difference between the amount of waste treated and the amount of biogas produced. The amount of waste processed is relatively high. In the actual field survey data, there were cases where biogas was not produced that day even if the waste was processed at the biogas production facility, so simple waste disposal statistics may not reflect this characteristic. Therefore, this study concludes that this difference is due to differences in the collection of related activity data.