Disinfection of Wastewater by UV-Based Treatment for Reuse in a Circular Economy Perspective. Where Are We at?

Abstract

Among the critical issues that prevent the reuse of wastewater treatment plants (WWTPs) effluents in a circular economy perspective, the microbiological component plays a key role causing infections and diseases. To date, the use of conventional chemical oxidants (e.g., chlorine) represent the main applied process for wastewater (WW) disinfection following a series of operational advantages. However, toxicity linked to the production of highly dangerous disinfection by-products (DBPs) has been widely demonstrated. Therefore, in recent years, there is an increasing attention to implement sustainable processes, which can simultaneously guarantee the microbiological quality of the WWs treated and the protection of both humans and the environment. This review focuses on treatments based on ultraviolet radiation (UV) alone or in combination with other processes (sonophotolysis, photocatalysis and photoelectrocatalysis with both natural and artificial light) without the dosage of chemical oxidants. The strengths of these technologies and the most significant critical issues are reported. To date, the use of synthetic waters in laboratory tests despite real waters, the capital and operative costs and the limited, or absent, experience of full-scale plant management (especially for UV-based combined processes) represent the main limits to their application on a larger scale. Although further in-depth studies are required to ensure full applicability of UV-based combined processes in WWTPs for reuse of their purified effluents, excellent prospects are presented thanks to an absent environmental impact in terms of DBPs formation and excellent disinfection yields of microorganisms (in most cases higher than 3-log reduction).

Metoprolol and Its Degradation and Transformation Products Using AOPs—Assessment of Aquatic Ecotoxicity Using QSAR

“…Comparison of all c-t curves suggested that for the elimination of metoprolol and its degradation products, UV-irradiation in combination with hydrogen peroxide might be the more efficient AOP. With respect to installation in WWTP, UV-irradiation based technical processes often suffer from high capital and operative costs and the limited or absent experience of full-scale plant management [ 12 ].…”

“…These comprise ozonation, UV radiation treatment, and the use of photocatalysts such as Photo-Fenton, hydrogen peroxide or titanium dioxide. A recent comprehensive survey on the UV based processes and their technical upscaling was conducted by Collivignarelli et al [ 12 ]. The AOPs lead to the formation of hydroxyl radicals that are able to destroy organic micropollutants, but the hydroxyl radicals can also attach themselves to the substances, leading to even more hazardous products [ 13 , 14 ].…”

Simultaneous Disinfection and Organic Microcontaminant Removal by UVC-LED-Driven Advanced Oxidation Processes

“…In this regard, the use of light-emitting diodes (LEDs) as a replacement for mercury lamps as a source of UV radiation is gaining growing interest [12]. This system has significant advantages, such as low power consumption, long lifetime (100,000 h), high spectral purity, uniform illumination, energy efficiency, and flexible configuration [13]. In terms of the emitting wavelength, the UV radiation electromagnetic spectrum is divided into UVA (315-400 nm), UVB (280-315 nm), and UVC (100-280 nm), with photonic energy of 3.10-3.94 eV, 3.94-4.43 eV, and 4.43-12.40 eV, respectively.…”

Advances in the Synthesis and Application of Anti-Fouling Membranes Using Two-Dimensional Nanomaterials

“…As water scarcity continues to be a global challenge, there is a need to explore various pathways to close the water consumption cycle at the nexus of food, water, and energy systems [ 1 ]. There is a paradigm shift needed towards the circular economy considering municipal and industrial wastewater as a valuable source of clean water, nutrients, and fertilizer instead of a grave environmental issue [ 2 ]. In fact, treated water has been considered as an alternative source to augment the clean water supply and tackle issues caused by a shortage of fresh water in different parts of the world, especially arid regions [ 1 ].…”