Fluorescent tracer trials are performed to obtain useful information for hydrodynamic modeling. Particularly they have
been used in constructed wetlands, aimed for residual water treatment, in order to find residence time distribution for
particles entering the system and, in general, to know the flux pattern. Nevertheless, it has been reported that some
tracers, as Rhodamine WT, exhibit adsorption phenomena over the substrate. This situation has to be considered in the
analysis of residence time distribution curves, taking into account advection-dispersion processes which are given by the
diffusion modified equation. Laser Induced Fluorescence (LIF) with a Nd:YAG laser (532 nm; 35mW), was used to
determine Rhodamine WT accumulated concentration. Through adsorption coefficients obtained experimentally, an
advection - dispersion model for solute transport in a subsurface flow constructed wetland was evaluated. Including this
phenomenon allows to optimize the model, and another important condition is added in the behavior prediction of these
Constructed wetlands are a very efficient, clean and economical way to remove organic contaminants from waste water.
In the whole water cleaning process, some other complex processes, such as physical sedimentation, filtration, chemical
precipitation, and material absorption by vegetation, are involved. The Nitrogen absorption efficiency by heliconnia
psitacorumm, was studied at laboratory scale in a small reactor simulating a subsurface flow constructed wetland.
Chlorophyll increasing was measured by fluorescence, using blue LED, 460 [nm] as excitation light source. Besides,
spectral differences were observed in the spectral signal and in its derivative, indicating changes in the plant