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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 [ABSTRACT FROM AUTHOR]

Microwave discharge electrodeless lamps (MDELs) have been examined for continuous on-site field treatment of contaminated water using solar cells to provide the necessary electrical power. The equipment aimed to decontaminate water in areas impacted by natural disasters such as the extensive earthquake that hit Eastern Japan in 2011. An energy-saving semiconductor microwave generator provided the microwaves to activate the MDELs in a microwave/UVreactor setup operated using a single- mode applicator and an E/H tuner. The herbicide 2,4-dichlorophenoxyacetic acid degraded within a shorter time compared to methylene blue at a defined flow rate through the microwave/UV reactor. Sterilization of natural water contaminated with the bacterial microorganism Escherichia coli was complete within 20 min. [ABSTRACT FROM AUTHOR]

The production of chemicals from lignin by green and sustainable technologies is a promising alternative route to replace fossil fuels. Photooxidation of guaiacol, a model of lignin, to value-added carboxylic acids with microwave discharge electrodeless lamps as light source was investigated in the presence of hydrogen peroxide (H2O2). The coupled UV-vis/microwave irradiation led to a more effective degradation of guaiacol than with conventional photocatalysis. Hydroxyl radicals as active species, confirmed by electron spin resonance spin-trapping, were generated and participated in the oxidation. The effect of different operating conditions such as reaction time, guaiacol concentration, solution pH, as well as oxidant concentration, was evaluated. [ABSTRACT FROM AUTHOR]

Biologically treated leachate usually contains considerable amount of refractory organics and trace concentrations of xenobiotic pollutants. Removal of refractory organics from biologically treated landfill leachate by a novel microwave discharge electrodeless lamp (MDEL) assisted Fenton process was investigated in the present study in comparison to conventional Fenton and ultraviolet Fenton processes. Conventional Fenton and ultraviolet Fenton processes could substantially remove up to 70% of the refractory organics in a membrane bioreactor treated leachate. MDEL assisted Fenton process achieved excellent removal performance of the refractory components, and the effluent chemical oxygen demand concentration was lower than 100 mg L−1. Most organic matters were transformed into smaller compounds with molecular weights less than 1000 Da. Ten different polycyclic aromatic hydrocarbons were detected in the biologically treated leachate, most of which were effectively removed by MDEL-Fenton treatment. MDEL-Fenton process provides powerful capability in degradation of refractory and xenobiotic organic pollutants in landfill leachate and could be adopted as a single-stage polishing process for biologically treated landfill leachate to meet the stringent discharge limit. [ABSTRACT FROM AUTHOR]

The destruction of low concentration of toluene (0-30 ppm) has been studied under the UV/photogenerated O3/MnO2-impregnated granular activated carbon (MnO2-impregnated GAC) process by the combination of self-made high frequency discharge electrodeless lamp (HFDEL) with MnO2-impregnated GAC catalyst. Experimental results showed that the initial toluene concentration can strongly affect the concentration of photogenerated O3 from HFDEL and the efficiency and mass rate of destruction of toluene via HFDEL/MnO2-impregnated GAC system. Active oxygen and hydroxyl radicals generated from HFDEL/MnO2-impregnated GAC system played a key role in the decomposition of toluene process and the intermediates formed by photolysis are more prone to be mineralized by the subsequent MnO2-impregnated GAC catalyst compared to the original toluene, resulting in synergistic mineralization of toluene by HFDEL/MnO2-impregnated GAC system. The role of MnO2-impregnated GAC catalyst is not only to eliminate the residual O3 completely but also to enhance the decomposition and mineralization of toluene. [ABSTRACT FROM AUTHOR]