Simulation Study On Transportation Of NH₃-N With Constructed Rapid Infiltration

As one type of land-treatment technologies ,Constructed rapid infiltration (CRI) system was stemmed from the fast infiltration systerm,which used the applicability of fast infiltration media to replace the natural soil. Compared with other ecological process ,the CRI system has the characteristics of high hydraulic loading and less land area possession.From the previous experiment, the characteristic of low nitrogen removal rate has restricted the CRI system. This article emphatically syudy the transportation of NH₃-N and NO₃-N in CRI systerm under a certain soil and climate conditions, and use the conclusion to simulate a NH₃-N transportation model. Through the analysis of NH₃-N and NO₃-N transportation process in the CRI system, we found that:Most NH₃-N are adsorpted in the CRI system at the water distribution phase, and the surface soil has the largest contribution to this process,and then the adsorpted NH₃-N would be oxidized to NO₃-N in the dry process, which would easily be outflowed from the soil at the beginning of water distribution in the second cycle.Through the research of NO₃-N transportation in the CRI system, we found that: the process of NO₃-N denitrification mainly occurred in the soil of 25-70cm department in the time of 9-24hours after water distribution.Through the use of NH₃-N transportation model to simulate the NH₃-N transportation process, we found that: the simulation and the measurement have a consistent trend, but need the join of error compensation to simulate the results.Through the sensitivity analysis of three main parameters: the block coefficient , the average pore velocity and vertical dispersion coefficient, we found the increasing of block coefficient and vertical dispersion coefficient would improve the removal of NH₃-N in CRI system,while the raising of average pore velocity will had a negative-effective to the removal of NH₃-N in CRI system. According to the analysis of importance of parameters on NH₃-N removal: the average pore velocity> the block coefficient> the vertical dispersion coefficient.