Effects of Nitrogen from Sewage with Different Treatment Levels on Farmland Soil Environment

Soil column model experiment was done for simulating two grades wastewater in soil.The characteristic of nitrogen accumulation and leaching in soil were investigated.For primary treatment of wastewater，experimental results showed that the level of ammonium nitrogen in the sewage basic would not accumulate in soil layers and leached while nitrate and total nitrogen concentration would be accumulated and leached in the depth soil with increase of irrigation frequency.For secondary treatment of wastewater，because of the low nitrogen concentration，concentration of each layer of soil was relatively low，and concentration of nitrogen in the soil was result of interaction of nitrogen in soil and nitrogen in sewage.With increase of irrigation times，the nitrate and total nitrogen had a downward trend.The test results also showed that，compared with secondary treatment wastewater，the first stage treatment of sewage irrigation would bring high pollution risk to soil environment and groundwater environment.