Interactions between H_(2)O_(2)and dissolved organic matter during granular activated carbon-based residual H_(2)O_(2)quenching from the upstream UV/H_(2)O_(2)process

Granular activated carbon(GAC)filtration can be employed to synchronously quench residual H_(2)O_(2)from the upstream UV/H_(2)O_(2)process and further degrade dissolved organicmatter(DOM).In this study,rapid small-scale column tests(RSSCTs)were performed to clarify the mechanisms underlying the interactions between H_(2)O_(2)and DOM during the GAC-based H_(2)O_(2)quenching process.It was observed that GAC can catalytically decompose H_(2)O_(2),with a long-lasting high efficiency(>80%for approximately 50,000 empty-bed volumes).DOM inhibited GAC-based H_(2)O_(2)quenching via a pore-blocking effect,especially at high concentrations(10 mg/L),with the adsorbed DOM molecules being oxidized by the continuously generated·OH;this further deteriorated the H_(2)O_(2)quenching efficiency.In batch experiments,H_(2)O_(2)could enhance DOM adsorption by GAC;however,in RSSCTs,it deteriorated DOM removal.This observation could be attributed to the different·OH exposure in these two systems.It was also observed that aging with H_(2)O_(2)and DOM altered the morphology,specific surface area,pore volume,and the surface functional groups of GAC,owing to the oxidation effect of H_(2)O_(2)and·OH on the GAC surface as well as the effect of DOM.Addi-tionally,the changes in the content of persistent free radicals in the GAC samples were insignificant following different aging processes.This work contributes to enhancing understanding regarding the UV/H_(2)O_(2)-GAC filtration scheme,and promoting the application in drinking water treatment.