Abstract
The method of rapid infiltration through soil lacks the ability in removing nitrogen from wastewater reason of insufficient of organic substances for denitrification in the anaerobic region. To urge the denitrification it was tried by pouring organic compounds into the deep region of the infiltrator, where the process of nitrification completed and the soils get to be anaerobic. For understanding the processes occurred in this procedure, the mathematical models (with the Finite Element Method) are presented to simulate the flowing and mixing processes occurred within the two-dimensional designed experimental apparatus. Because the hydraulic conductivity of water in variably saturated soils depends on pressure head and water content, this problem is strongly nonlinear. To solve this problem, the Newton-Rampson method have been utilized and the calculated results agree well with that of experimental ones. From the calculated results, a low ratio of denitrification is presumable according to the low mixing between these organic matters and nitrate by means of supplying organic substancs from single point.
