Relationships of nitrous oxide fluxes with water quality parameters in free water surface constructed wetlands

The effects of chemical oxygen demand (COD) concentration in the influent on nitrous oxide (N2O) emissions, together with the relationships between N2O and water quality parameters in free water surface constructed wetlands, were investigated with laboratory-scale systems. N2O emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent, and the total N2O emission in the system with middle COD influent concentration was the least. The relationships between N2O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear regression analysis to predict N2O flux. The multiple linear regression model against principal components indicated that different water parameters affected N2O flux with different COD concentrations in the influent, but nitrate nitrogen affected N2O flux in all systems.