Kinetic behavior and modeling the space distribution of basic pollutants in a subsurface flow constructed wetlands with Pontederia cordata

Abstract

Water pollution is one of the most serious environmental problems nowadays, so it is relevant to study improvements in the wastewater treatment system. In this work, the kinetics of experimental degradation of basic pollutants were evaluated, as well as the behavior of their spatial distribution, within a subsurface flow constructed wetland (SSFCW) with Pontederia cordata. To achieve so, a factor design was made with five treatments at different planting distances within wetland (0, 0.42, 1.25, 2.08 and 2.4 m) with three replicates and nine sampling points. The experimental reactors showed a hydraulic retention time of 4.5 days, treating 185.1±58.6 L/day of wastewater, with river gravel as support medium with a volume of 0.66±0.05 m3, porosity n=56±3.5%, density of 2670±19.3 kg/m3, allowing a water volume of 0.1±0.05 m3. In the evaluation phase, a k of -0.37 days-1 was obtained, removing 81.8% of BOD5 and 70% turbidity. With the modeling of the spatial distribution, it was demonstrated that the biomass (microorganisms) adhered to the support medium, as well as the BOD5, have a significant decrease related to the distance within the SSFCW throughout the reactor. The contaminant removal efficiency is presented from the distance 2.08 to 2.4 m in length within the experimental wetland.