Assessment of the nutrient removal performance in integrated constructed wetlands with the self-organizing map

The self-organizing map (SOM) model was applied to predict outflow nutrient concentrations for integrated constructed wetlands (ICWs) treating farmyard runoff. The SOM showed that the outflow ammonia-nitrogen concentrations were strongly correlated with water temperature and salt concentrations, indicating that ammonia-nitrogen removal is effective at low salt concentrations and comparatively high temperatures in ICWs. Soluble reactive phosphorus removal was predominantly affected by salt and dissolved oxygen concentrations. In addition, pH and temperature were weakly correlated with soluble reactive phosphorus removal, suggesting that soluble reactive phosphorus was easily removed within ICWs, if salt concentrations were low, and dissolved oxygen, temperature and pH values were high. The SOM model performed very well in predicting the nutrient concentrations with water quality variables such as temperature, conductivity and dissolved oxygen, which can be measured cost-effectively. The results indicate that the SOM model was an appropriate approach to monitor wastewater treatment processes in ICWs.