Attenuation of Erythromycin-laden wastewater using constructed wetland technique

Erythromycin (ERY) is environmentally resilient because of its aromatic nature, which hinders degradation. In the present study, silty-sandy soil, having a saturated hydraulic conductivity value (K) of 1.66 x 10(-7) m/s, has been studied for its potential to remove aqueous erythromycin using a laboratory-scale constructed wetland. With a dose of 10 g/l, concentration of 25 mg/l, and a contact time of 30 minutes, maximum adsorption reached 89.79 +/- 1.5 %, as found from batch experiments. The Freundlich isotherm (R-2 = 0.983, n = 0.575, K-f = 0.04 mg/g) was the best fitting among different user models. In the kinetic study, the Pseudo-second order model (qe = 1.297 mg/g, K-2 = 0.182 g/mg min) had the best fit with experimental data. A one-dimensional vertical column study exhibited an exhaustion time of 2.7 days for 40 mm deep soil bed to remove ERY. A laboratory-scale constructed wetland model composed of silty sandy soil showed a reduction of ERY 92.44%. Finally, the results were validated with CW2D wetland model of HYDRUS, which corroborated the experimental results. The outcome entails that constructed wetlands with silty-sandy soil may be an effective technique for the reduction of ERY present in wastewater, which has profound importance from a social health perspective.

Automated summary

This study investigates the potential of silty-sandy soil in a laboratory-scale constructed wetland to remove aqueous erythromycin. The maximum adsorption reached 89.79% in batch experiments with a dose of 10 g/l, concentration of 25 mg/l, and a contact time of 30 minutes. The Pseudo-second order model provided the best fit in the kinetic study. A one-dimensional vertical column study showed that a 40 mm deep soil bed could remove erythromycin within 2.7 days.