As an advanced oxidation process, vacuum ultraviolet/ultraviolet (VUV/UV) has been intensively studied for drinking water treatment, but assessment of its feasibility for wastewater treatment has rarely been conducted. This study investigated the treatment of fluorine-containing pharmaceutical wastewater by VUV/UV process and examined the defluorination and therefore the improvement of biodegradability of the wastewater after the process. The results indicated that the degradation of a model fluorine-containing organic compound (namely, 4-fluorophenol) was mainly achieved via the attack of the fluorine atom linking directly to the aromatic ring by the HO• generated from VUV photolysis of water. As the solution pH increased from 4.0 to 10.0, the COD removal efficiency of the real pharmaceutical wastewater decreased slightly from 18.1 to 15.9%, while the release ratio of F- increased from 50.8 to 75.5%. As the dissolved oxygen increased from 0.15 to 12 mg L-1, the removal efficiency of COD and the release ratio of F- increased from 9.2 to 17.1% and from 48.2 to 75.5%, respectively. The biodegradability index (BOD/COD) increased significantly from 0.24 to 0.47 after the VUV/UV irradiation, which confirmed the feasibility of applying the VUV/UV process for improving biodegradability of the pharmaceutical wastewater.
Keywords: Biodegradability; Defluorination; Pharmaceutical wastewater; VUV/UV.
© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.