Influence of the geometric configuration of unplanted horizontal subsurface flow constructed wetlands in the adjustment of parameters of organic matter decay models

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

“…Before being added to the fiberglass boxes, the gravel was passed through a 2 mm mesh sieve to remove the fine fraction. The units were maintained unplanted so that there was no other factor influencing the hydraulic characteristics and degradation of the organic matter (Matos, von Sperling, Matos, & Passos, 2015;Matos et al, 2018). Table 1.…”

“…According Matos et al (2018), based on the suggestion of von Sperling by personal communication in 2016, the analysed MFOKM equation Equation 1developed by Brasil et al (2007) proposed developments of the exponential term, in a similar way to what was undertaken by Shepherd et al (2001), i.e. the insertion of an adjustment for the organic matter decay coefficient with the HRT, so that it would be possible to show the cited model in the FOKM format, as shown in Equation 2. k B .…”

“…It has recently been suggested that the interdependence between hydraulics and kinetics is very strong and influenced by several factors, and that even the latest generation of mathematical models has been considered inadequate to fully explain the observed behaviour and provide a reliable estimate of the parameters (Marsili-Libelli & Checchi, 2005, Matos, Matos, Costa, & von Sperling, 2018. Therefore, it is necessary to expand the knowledge regarding the hydraulic behaviour of HSSF-CWs in order to improve estimates of the kinetic removal rate and to obtain satisfactory predictions of pollutant efficiency in these systems (Garcia et al, 2004).…”

“…Therefore, it is necessary to expand the knowledge regarding the hydraulic behaviour of HSSF-CWs in order to improve estimates of the kinetic removal rate and to obtain satisfactory predictions of pollutant efficiency in these systems (Garcia et al, 2004). For these reasons, some adaptations to the FOKM have been proposed (Laber, Habert, & Shrestha, 1999, Shepherd et al, 2001, Brasil, Matos, Silva, Cecon, & Soares, 2007, Matos et al, 2018.…”

“…According to Brasil et al (2007) and Matos et al (2018), variation in the decay coefficient of the organic material in the wastewater under treatment in HSSF-CWs can be associated to both the decrease in the easily degradable organic fraction, which occurs as the wastewater moves towards the outlet of the reactor, and to changes in the hydraulic behaviour inside the system, especially with regards to the decrease in the HRT. These authors proposed the insertion of a coefficient n, as a power parameter of the HRT variable, in the FOKM, to give Equation 1 which expresses the Modified First Order Kinetic Model (MFOKM) and provides good fit to the experimental data obtained by different authors and several different wastewaters (Brasil et al, 2007, Matos et al, 2018).…”