Disinfection behavior of a UV-treated wastewater system using constructed wetlands and the rate of reactivation of pathogenic microorganisms

The use of constructed wetlands as a wastewater treatment system is a feasible solution for rural areas. However, these systems do not efficiently eliminate pathogenic microorganisms. Therefore, it is necessary to implement disinfection systems such as ultraviolet (UV) disinfection systems in constructed wetlands. To evaluate the behavior of a UV system, a pilot system of artificial wetlands connected to one such disinfection system was operated. The results show that when the total suspended solids (TSS) of the influent (already treated by the system of constructed wetlands) reached values of 26.7 mg/L, a reduction of 2.03 uLog in fecal coliforms was obtained. However, when the TSS increased to 34.7 mg/L, the reduction was only 0.33 uLog. In addition to the influence of the TSS on the fecal coliform reduction efficiency, there is a direct relationship between the transmittance and the sizes of the particles present in the influent. After UV treatment, the microorganisms showed a peak in photoreactivation of 27.8% at 4 h after irradiation with visible radiation, while under conditions of darkness, no reactivation was observed.