Analysis of conservative tracer measurement results using the Frechet distribution at planted horizontal subsurface flow constructed wetlands filled with coarse gravel and showing the effect of clogging processes

Abstract

A mathematical process, developed in Maple environment, has been successful in decreasing the error of measurement results and in the precise calculation of the moments of corrected tracer functions. It was proved that with this process, the measured tracer results of horizontal subsurface flow constructed wetlands filled with coarse gravel (HSFCW-C) can be fitted more accurately than with the conventionally used distribution functions (Gaussian, Lognormal, Fick (Inverse Gaussian) and Gamma). This statement is true only for the planted HSFCW-Cs. The analysis of unplanted HSFCW-Cs needs more research. The result of the analysis shows that the conventional solutions (completely stirred series tank reactor (CSTR) model and convection-dispersion transport (CDT) model) cannot describe these types of transport processes with sufficient accuracy. These outcomes can help in developing better process descriptions of very difficult transport processes in HSFCW-Cs. Furthermore, a new mathematical process can be developed for the calculation of real hydraulic residence time (HRT) and dispersion coefficient values. The presented method can be generalized to other kinds of hydraulic environments.

Analysis of conservative tracer measurement results inside a planted horizontal subsurface flow constructed wetland filled with coarse gravel using Frechet distribution

“…Further details are found in Dittrich and Klincsik (2015a). The mathematical procedure was published in Dittrich and Klincsik (2015a). Dittrich and Klincsik (2015a) demonstrated that the Frechet distribution is the best-fitting function to effluent point measurement results.…”

“…The mathematical procedure was published in Dittrich and Klincsik (2015a). Dittrich and Klincsik (2015a) demonstrated that the Frechet distribution is the best-fitting function to effluent point measurement results. The results show that Frechet had the best average R 2 of the effluent measurement point.…”

“…In tracer test analysis, scientists do not usually measure porosity; instead, they use the porosity value of newly built filter media before starting the operation or they estimate porosity (Schierup et al 1990;Tanner and Sukias 1995). In our study (Dittrich and Klincsik 2015a), by measuring the porosity of the analysed HSFCW-C, a very precise analysis was performed. Our results show that the effective porosity of the HSFCW-C decreased by more than 50% in the first 6 months as a result of intense biological activity and root growth.…”

Explicit Residence Time Distribution of a Generalised Cascade of Continuous Stirred Tank Reactors for a Description of Short Recirculation Time (Bypassing)

“…Martin [25] generalised the TIS model to non-integer n ≥ 1 to fine-tune the resulting RTD. This generalisation has been used as a stand-alone model and as a building block in reactor networks [13,24,[26][27][28]. Toson et al [29] used the model with a narrow parameter range 0.5 < n < 1.1 to fit the RTD of a continuous powder mixer and linked n to the quality of the mixing process.…”

Influence factors in the adjustment of parameters of the modified first-order kinetics equation used to model constructed wetland systems

“…The First Order Kinetic Model (FOKM) is the most utilized model for describing the process (Kadlec & Wallace, 2008), however it has not shown good fit to the experimental data because the reactors do not presented an ideal hydraulic behaviour, due to the occurrence of flow anomalies such as dispersion, shortcircuits and the presence of dead zones (Dittrich & Klincsik, 2015), and due to the decay coefficient of organic material suspended in wastewater which varies with the hydraulic retention time (HRT) (Shepherd, Tchobanoglous, & Grismer, 2001). According to Langergraber et al (2009), the simplified assumption of an ideal plug-flow in HSSF-CWs may introduce significant errors to the parameters, as well as the HRT, and consequently on the pollutant removal estimates.…”