Disinfection of municipal secondary effluents with microwave‐induced electrodeless ultraviolet irradiation for water reuse

Abstract

Abstract BACKGROUND Disinfection is an essential way to ensure the safety of recycled water. Ultraviolet ( UV ) is an effective and environmentally friendly technique suitable for the disinfection of recycled water. However, UV disinfection also leads to photoreactivation. This work proposes a combined use of UV irradiation and microwave technique to compensate for the limitations of UV disinfection. RESULTS The process of microwave‐induced electrodeless ultraviolet ( MW‐EUV ) irradiation was utilized to disinfect municipal secondary effluents. A homemade columnar electrodeless UV lamp was used as the source of UV irradiation. Good disinfection results under optimal microwave power at 600 W were obtained. There was no photoreactivation after sufficient irradiation. Cell damage to Escherichia coli by MW‐EUV irradiation was investigated by measuring the leakage of K + and protein from cells and was observed by atomic force microscopy ( AFM ). CONCLUSION The MW‐EUV irradiation was demonstrated to be a faster and more effective disinfection method than UV or microwave irradiation alone. The irradiated samples met the hygiene standard for the reuse of urban recycling water (Standard Number GB /T 18920–2002) in China. Disinfection depended mainly on UV irradiation, while microwaves were the main cause of bacterial breakup and deformation. This irreversible damage offsets the biological self‐healing phenomenon of UV disinfection. © 2016 Society of Chemical Industry