3.2 Nitrous oxide (N2O) emission calculating principles

Nitrogen oxides are associated with microbial conversion of nitrogen compound in wastewater and emerge as emissions from wastewater discharge to waterways, lakes, or seas and treatment plants or wastewater. The emission factor (0.005) is taken for domestic wastewater nitrogen effluent, referring to the default value recommended by IPCC [16]. The factor 44/28 is the conversion of kg N2O-N into kg N2O. A simplified equation is given in Eq. (8).

N2O emissions from constructed wetlands

$$\text{(N\_2O emissions)} = \sum\_{j} \left(\text{N}\_{j} \cdot \text{EF}\_{j} \cdot 44/28\right) + \sum\_{i,j} \left(\text{N}\_{i,j} \cdot \text{EF}\_{j} \cdot 44/28\right) \tag{8}$$

where N2O emissions, N2O emissions in inventory year, kg N2O/year; Nj, total nitrogen in domestic wastewater entering CWs in the inventory year, kgN/year; Ni,j, total nitrogen in industrial wastewater entering CWs in the inventory year, kgN/year; EFj , emission factor, kg N2O-N/kg N. If more than one type of CW is used in an industrial sector, this factor would need to be a Ni,j weighted average: i, industrial sector; j, type of CW; 44/28, the factor 44/28 is the conversion of kg N2O-N into kg N2O.
