Effect of coupled UV-A and UV-C LEDs on both microbiological and chemical pollution of urban wastewaters

Wastewater reuse for irrigation is an interesting alternative for many Mediterranean countries suffering from water shortages. The development of new technologies for water recycling is a priority for these countries. In this study we test the efficiency of UV-LEDs (Ultraviolet-Light-Emitting Diodes) emitting UV-A or UV-C radiations, used alone or coupled, on bacterial and chemical indicators. We monitored the survival of fecal bioindicators found in urban wastewaters and the oxidation of creatinine and phenol which represent either conventional organic matter or the aromatic part of pollution respectively. It appears that coupling UV-A/UV-C i) achieves microbial reduction in wastewater more efficiently than when a UV-LED is used alone, and ii) oxidizes up to 37% of creatinine and phenol, a result comparable to that commonly obtained with photoreactants such as TiO2.

► We test UV-LEDs as an urban wastewater tertiary treatment.
► UV-A and UV-C are coupled, combining germicidal and oxidative properties of UV.
► Coupled wavelengths have the most efficient bactericidal effect.
► Coupling UV-A and UV-C leads to photooxidation of creatinine and phenol.