title: Application of divided convective-dispersive transport model to simulate conservative transport processes in planted horizontal sub-surface flow constructed wetlands.
abstract: We have created a divided convective-dispersive transport (D-CDT) model that can be used to provide an accurate simulation of conservative transport processes in planted horizontal sub-surface flow constructed wetlands filled with coarse gravel (HSFCW-C). This model makes a fitted response curve from the sum of two independent CDT curves, which show the contributions of the main and side streams. The analytical solutions of both CDT curves are inverse Gaussian distribution functions. We used Fréchet distribution to provide a fast optimization mathematical procedure. As a result of our detailed analysis, we concluded that the most important role in the fast upward part of the tracer response curve is played by the main stream, with high porous velocity and dispersion. This gives the first inverse Gaussian distribution function. The side stream shows slower transport processes in the micro-porous system, and this shows the impact of back-mixing and dead zones, too. The significance of this new model is that it can simulate transport processes in this kind of systems more accurately than the conventionally used convective-dispersive transport (CDT) model. The calculated velocity and dispersion coefficients with the D-CDT model gave differences of 24-54% (of velocity) and 22-308% (of dispersion coeff.) from the conventional CDT model, and were closer to actual hydraulic behaviour.
authors.affiliation: Pollack Mihály Faculty of Engineering and Informatics, Department of Environmental Engineering, University of Pécs, Boszorkány u. 2, H-7624, Pécs, Hungary. dittrich@pmmik.pte.hu.
authors.forename: Ernő
authors.identifier: http://orcid.org/0000-0003-3964-2011
authors.initials: E
authors.lastname: Dittrich
authors.affiliation: Pollack Mihály Faculty of Engineering and Informatics, Department of Mathematical Sciences, University of Pécs, Pécs, Hungary.
authors.forename: Mihály
authors.initials: M
authors.lastname: Klincsik
mesh_terms: D008962:Models, Theoretical; D014872:Water Movements; D053833:Wetlands
keywords: Divided convective-dispersive transport (D-CDT) model; Fréchet distribution; Inverse Gaussian distribution; Sub-surface flow constructed wetlands; Tracer test; Transport processes