The impact of UVC and VUV treatment on the toxicity, leaching and degradation of tire rubber microplastic
Author
Nielsen, Emil Bock
Term
4. Term
Publication year
2022
Submitted on
2022-06-10
Pages
58
Abstract
Tire rubber microplastics (TRMP) are a significant yet often overlooked source of microplastics and associated toxic substances in aquatic environments. At the same time, short-wavelength UV technologies (UVC and VUV) are used in water treatment, where TRMP and their leachates may be exposed. This study investigates how 254 nm UVC and a combined 185/254 nm VUV/UVC irradiation affect both the leaching of toxic compounds from TRMP particles and the removal of these compounds from particle-free leachates. TRMP suspended in tap water and particle-free leachates were irradiated in a collimated beam setup at varying exposure durations. Toxicity was assessed as growth inhibition of the green alga Raphidocelis subcapitata, and selected contaminants were quantified as zinc and polycyclic aromatic hydrocarbons (PAHs; fluoranthene, pyrene, and benzo(a)pyrene) using a photometric zinc test and gas chromatography. The results showed that both UVC and VUV/UVC promoted the leaching of toxic compounds from TRMP particles. Conversely, treating particle-free TRMP leachates with UVC and especially VUV/UVC reduced toxic compounds; UVC removed 66% of measured PAHs, while VUV/UVC removed 88%. Overall, the findings indicate that VUV/UVC treatment has potential to mitigate the load of toxic compounds from TRMP in aquatic environments, while also highlighting that UV exposure of the particles themselves can increase leaching.
Tire rubber mikroplast (TRMP) er en væsentlig, men ofte overset kilde til mikroplast og tilhørende toksiske forbindelser i vandmiljøet. Samtidig anvendes kortbølget UV-teknologi (UVC og VUV) i vandbehandling, hvor TRMP og deres udvaskede stoffer kan blive eksponeret. Dette projekt undersøger, hvordan 254 nm UVC og en kombination af 185/254 nm VUV/UVC påvirker både udvaskning af toksiske forbindelser fra TRMP-partikler og fjernelse af disse forbindelser fra partikel-frie eluater. TRMP i postevand og partikel-frie eluater blev belyst i en kollimeret stråleopstilling ved varierende eksponeringstider. Toksicitet blev vurderet som væksthæmning af grønalgen Raphidocelis subcapitata, og udvalgte forurenende stoffer blev kvantificeret som zink og polycykliske aromatiske kulbrinter (PAH; fluoranthen, pyren og benzo(a)pyren) ved fotometrisk zinktest og gaskromatografi. Resultaterne viste, at både UVC og VUV/UVC øgede udvaskningen af toksiske forbindelser fra TRMP-partikler. Omvendt reducerede behandling af partikel-frie TRMP-eluater med UVC og især VUV/UVC indholdet af toksiske forbindelser; UVC fjernede 66 % af de målte PAH’er, mens VUV/UVC fjernede 88 %. Samlet peger studiet på, at VUV/UVC-behandling har potentiale til at afbøde belastningen af toksiske forbindelser fra TRMP i vandmiljøet, samtidig med at det fremhæver, at UV-eksponering af selve partiklerne kan øge udvaskningen.
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