Nitrogen wastewater irrigation study and its contamination risk analysis

Based on the nitrogen wastewater irrigation experiments carried out in the field experimental base,the movement and transformation regularities of nitrogen compound in wastewater irrigation were analyzed in this paper.The results showed that wastewater irrigation had a little influence on the ammonium concentration in deep-depth soil solution,but a big influence on the nitrate concentration in groundwater,especially in the soil with seriously wastewater irrigation before.The mathematical model,which was developed in the paper,could be used to predict the temporal and spatial distribution of ammonium-N and nitrate-N in soil solution and groundwater.The groundwater contamination risk analysis was conducted by using the Monte-Carlo simulation techniques.It is noteworthy that the maximum nitrate-N concentration at 5m depth of groundwater level is predicted to be great than 0.76 times of nitrate-N concentration in irrigated wastewater with 25% probability,and great than 0.43 times with 75% probability.Groundwater contamination risk should be considered in wastewater irrigation.