A comparison of three different residence time distribution modelling methodologies for horizontal subsurface flow constructed wetlands

We worked out a method in Maple environment to help understand the difficult transport processes in horizontal subsurface flow constructed wetlands filled with coarse gravel (HSFCW-C). With this process, the measured tracer results of the inner points of a HSFCW-C can be fitted more accurately than with the conventionally used distribution functions (Gaussian, Lognormal, Fick (Inverse Gaussian) and Gamma). This research outcome only applies for planted HSFCW-Cs. The outcome of the analysis shows that conventional solutions completely stirred series tank reactor (CSTR) model and convection-dispersion transport (CDT) model do not describe the internal transport processes with sufficient accuracy. This study may help us develop better process descriptions of very complex transport processes in HSFCW-Cs. Our results also revealed that the tracer response curves of planted HSFCW-C conservative inner points can be fitted well with Frechet distribution only if the response curve has one peak.

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“…This means that the main flow is at the bottom. Bonner et al (2016) and Liu et al (2018) came to a similar conclusion from their results.…”

Section: Resultssupporting

confidence: 71%

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

Dittrich

Klincsik

Somfai

et al. 2020

Environ Sci Pollut Res

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“…Richter et al (2003) measured HSFCW and were the first in the literature who found that the actual HRT could be higher than the theoretical HRT; however, they didn't find the reason for this phenomenon. Bonner et al (2017) completed a tracer test on laboratoryscale HSFCWs with red fluorescent dye used as tracer. There were 13 sampling points in the CW.…”

Section: Introductionmentioning

confidence: 99%

“…Bonner et al ( 2017 ) completed a tracer test on laboratory-scale HSFCWs with red fluorescent dye used as tracer. There were 13 sampling points in the CW.…”

Section: Introductionmentioning

confidence: 99%

Application of divided convective-dispersive transport model to simulate variability of conservative transport processes inside a planted horizontal subsurface flow constructed wetland

Dittrich

Klincsik

Somfai

et al. 2020

Environ Sci Pollut Res

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This paper offers a novel application of our model worked out in Maple environment to help understand the very complex transport processes in horizontal subsurface flow constructed wetland with coarse gravel (HSFCW-C). We made tracer measurements: Inside a constructed wetland, we had 9 sample points, and samples were taken from each point at two depths. Our model is a divided convective-dispersive transport (D-CDT) model which makes a fitted response curve from the sum of two separate CDT curves showing the contributions of the main and side streams. Analytical solutions of CDT curves are inverse Gaussian distribution functions. This model was fitted onto inner points of the measurements to demonstrate that the model gives better fitting to the inner points than the commonly used convective-dispersive transport model. The importance of this new application of the model is that it can resemble transport processes in these constructed wetlands more precisely than the regularly used convective-dispersive transport (CDT) model. The model allows for calculations of velocity and dispersion coefficients. The results showed that this model gave differences of 4–99% (of velocity) and 2–474% (of dispersion coefficient) compared with the CDT model and values were closer to actual hydraulic behavior. The results also demonstrated the main flow path in the system.

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“…However, the water path can be very complex due to particle size distribution and uniformities of the granular media packing, the development of biofilms and, particularly, the spread of the plants' roots. As a result, the water flow is usually modeled empirically using tracer experiments [3,4].…”

Section: Introductionmentioning

confidence: 99%

Tracer experiments with lithium chloride to evaluate the hydrodynamics of constructed wetlands. Comparison of alternative analytical methods

Pinho

Mateus

Alves

et al. 2019

Proceedings of the International Conference of Computational Methods in Sciences and Engineering 2019 (Iccmse-2019)

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The characterization of water flow dynamics (hydrodynamics) through constructed wetlands is relevant for optimizing wastewater treatment. Although constructed wetlands consist of simple systems, the water flow is complex and irregular, therefore, the study of hydrodynamics requires the use of experimental technics such as tracer experiments. To evaluate the effects of the use of three different analytical methods to compute the concentration of lithium chloride on the main hydrodynamics parameters, tracer experiments were conducted in ten independent lab-scale constructed wetlands. The concentration of lithium chloride in the output flow of the wetlands was calculated by flame photometry, electrical conductivity using a calibration curve and electrical conductivity using the salt molar conductivity. The paired samples Ttest or the non-parametric Wilcoxon's Signed-Ranks test were used to demonstrate that the computed hydraulic retention time and the number of tanks accordingly with the tanks-in-series model were not significantly affected by the selected analytical method.

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A comparison of three different residence time distribution modelling methodologies for horizontal subsurface flow constructed wetlands

Cited by 17 publications

References 69 publications

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

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

Application of divided convective-dispersive transport model to simulate variability of conservative transport processes inside a planted horizontal subsurface flow constructed wetland

Tracer experiments with lithium chloride to evaluate the hydrodynamics of constructed wetlands. Comparison of alternative analytical methods

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