Treatment of organic wastewater by a combination of non-thermal plasma and catalyst: a review

Recently, non-thermal plasma technology has been frequently used for wastewater treatment. Plasma technology uses the effect of high-energy electrons, reactive species, ultraviolet light, free radicals, and pyrolysis to treat wastewater. Although in many cases, only the use of non-thermal plasma alone is not successful in degrading the complex organic wastes. This might be because of complexity in wastewater or not appropriate plasma device for wastewater treatment, or improper use of plasma-generated species that plays a critical role in organic waste degradation. To increase the degradation efficiency and reduce treatment time, the combination of non-thermal plasma and catalysts (homogeneous and heterogeneous) improves pollutant removal. This review includes the different non-thermal plasma systems and their action on decolorizing or degradation of dyes, degradation of phenolic pollutants, and degradation of pharmaceutical products, including antibiotics and other volatile organic solvents (VOC’s) with and without catalyst. Finally, probable mechanisms and suggestions to improve the wastewater treatment using non-thermal plasma were put forward. This review aims to help researchers understand the role of treatment time, feed gases, and catalysts on the degradation of organic wastes and looks forward to all possible developments in this field.