Experimental Research on Tracing Degradation Principle of Leachate 15N

Simulated semi-aerobic landfill equipment and anaerobic landfill equipment (CK) were installed, and the in-situ trace experiment based on the ¹⁵N isotope technique was carried out. The two equipments were respectively added with 4 g standard ¹⁵NH₄Cl tracer(the abundance of ¹⁵N is 99.6%), and leachate samples at the bottom of the equipments were taken at 20 h, 44 h, 68 h, 116 h and 188 h after the tracer was added, to detect the concentration of total nitrogen (TN) and the abundance of ¹⁵N of TN. The migration rules of extraneous source ¹⁵N during the semi-aerobic and anaerobic landfilling process in the leachate, and the dynamic degradation principles of nitrogen element in both complicated nitrogen pool treating system were discussed. Results showed that, dilution factor (x_i) of extraneous source ¹⁵N of the semi-aerobic treatment nitrogen pool at 20 h ,44 h, 68 h, 116 h and 188 h was attenuated in turn, and x_i of those of anaerobic treatment nitrogen pool after 20 h, 44 h, 68 h and 116 h was also attenuated in turn, while the values of x_i at 116 h and 188 h was equal. Contents of ¹⁵TN (m_i) in the bottom leachate of both treating pools and the percentage y_i that m_i occupies in TN (M_i,1042.54/x_i) of the nitrogen pool were augmented with the time lapse of anaerobic treatment were both obviously larger than those of corresponding semi-aerobic treatment at each monitoring time point, while xt showed an opposite rule. Semi-aerobic treatment could reach a migration and transfer balance and a stable degradation status of the system earlier than the anaerobic treatment, and the average variation speeds of m_i and x_i of semi-aerobic treatment were obviously larger than those of the anaerobic treatment under these balance status, the variation rate of m_i and x_i- of the anaerobic treatment were very small (near zero) or equal to zero.