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

Abstract

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.

Organic Compounds and Antibiotic-Resistant Bacteria Behavior in Greywater Treated by a Constructed Wetland

“…The effluents assessed in this study contain TC and FC concentrations of 7.6 × 10 5 and 1.9 × 10 4 MPN/100 mL. This is consistent with the findings of various authors, who state that CW systems are not designed for the removal of E. coli, coliforms, or helminth eggs [9,26,50]. Because bacteria require more than 10 3 cells to cause an infection [59], the fecal load present in the effluents can pose a health risk in any projected reuse without prior disinfection treatment [50,63].…”

“…However, the biodegradation capacity of the influents could be decreased due to the presence of surfactants and low nutrient loads [12]. In addition, it has been reported that CWs are not efficient for pathogen removal and could trigger the spread of resistance into the environment [17,26,27].…”

Study of coliforms and Clostridium bacteria inactivation in wastewaters by a pilot photolysis process and by the maturation lagoons of a low-cost nature-based WWTP

“…Furthermore, disinfection is required in some areas to fulfil certain directives, such as the Habitats Directive (92/43/EEC) and Bathing Water Directive (2006/7/EC). The level of disinfection of microorganism is insufficient in constructed wetlands (López et al 2019 ), which is why some authors propose the use of UV photolytic reactors (Azaizeh et al 2013 ; González et al 2019 ) and others the use of maturation lagoons (Tanner et al 2005 ; Russo et al 2020 ).…”

Constructed wetlands to treat polluted waters in Latin America and the Caribbean

“…Este proyecto se puso en marcha el año 2011 y se ha generado investigación con conclusiones muy relevantes, respecto de la materia orgánica los sistemas lograron una eficiencia de eliminación de materia orgánica entre 69-72%. Sin embargo, tienen una baja capacidad de eliminación de nutrientes con eficiencia de eliminación de nitrógeno total de 37-44% y de fósforo total de 19-29% y para la desinfección de aguas es necesario un sistema terciario(Araya et al, 2016, Andrés et al, 2018, Leiva et al, 2020, González et al, 2020, Carrillo et al, 2022. También juega un rol relevante si las plantas macrófitas…”