Trace Organic Pollutant Removal by VUV/UV/chlorine Process: Feasibility Investigation for Drinking Water Treatment on a Mini-Fluidic VUV/UV Photoreaction System and a Pilot Photoreactor

Abstract

The vacuum-ultraviolet/ultraviolet/chlorine (VUV/UV/chlorine) process, with a VUV/UV mercury lamp used as the light source, was found to be a highly efficient advanced oxidation process (AOP) in a previous study. Hence, its application feasibility for trace organic pollutant removal from drinking water becomes attractive. In this work, a bench-scale mini-fluidic VUV/UV photoreaction system was used to determine the degradation kinetics of sulfamethazine (SMN), a model sulfonamide antibiotic frequently detected with trace levels in aquatic environments. Results indicated that SMN (0.1 mg L) could be degraded rapidly by VUV/UV/chlorine, and a synergism was observed between the VUV/UV and UV/chlorine processes. Photon-fluence based rate constants of SMN degradation were determined to be 6.76 × 10 and 8.51 × 10 m einstein at chlorine doses of 0.05 and 0.5 mg L, respectively. The presence of natural organic matter in real waters significantly inhibited SMN degradation. In addition, pilot tests were conducted to explore the practical performance of the VUV/UV/chlorine process, thereby allowing electrical energy per order to be calculated for cost evaluation. The effect of flow pattern on photoreactor efficiency was also analyzed by computational fluid dynamics simulations. Both bench- and pilot-scale tests have demonstrated that the VUV/UV/chlorine process, as a new AOP, has potential applications to trace organic pollutant removal in small-scale water treatment.

State of the Art of UV/Chlorine Advanced Oxidation Processes: Their Mechanism, Byproducts Formation, Process Variation, and Applications

“…They mentioned that the synergistic effect of VUV radiation on UV/chlorine system was mainly ascribed to the effective use of HO˙ for methylene blue removal through formation of longer-lived secondary radicals like ClO˙ produced by reaction R 1 in Table 1. The research group of Li et al also discussed sulfamethazine degradation using the same system and observed similar results, namely >1.6-times higher degradation rate by the VUV-emitted LP-UV/chlorine process than the sum of those by the controls [104].…”

“…If 185 nm radiation is unnecessary, soft glass (sodium-barium-glass) is available, which transmits more than 80% of UV light at 254 nm, but cuts off 185 nm light [102]. Two papers have been published, in which effect of vacuum UV light (VUV light at 185 nm) emitted from LP-UV lamps on UV/chlorine AOPs was discussed [103,104]. Li et al discussed methylene blue degradation using a VUV-emitted and VUV-free LP-UV/chlorine systems [103].…”

“…There is no report on excimer-UV/chlorine AOPs. However, since it was reported that VUV-emitted LP-UV/chlorine processes has a synergistic effect on pollutants removal compared with VUV-free LP-UV/chlorine process and VUV photolysis [103,104], excimer lamps using Ar 2 *, Kr 2 *, or Xe 2 * may enhance the performance of UV/chlorine AOPs. A XeCl* excimer lamp is another candidate of an UV light source for UV/chlorine AOPs at a basic pH, because emission spectrum of XeCl* excimer lamp accords with the absorption peak of ClO − (Fig.…”

Effect of UV-A, UV-B and UV-C irradiation of glyphosate on photolysis and mitigation of aquatic toxicity

“…Nonetheless, further studies should focus on UV effects at lower glyphosate concentrations and the applicability for different water types and under different hydraulic conditions. Such studies may also include UV techniques such as Vacuum UV that will likely increase oxidation potential and contaminant removal 46 , 47 . Because the suggested UV based techniques are fundamentally non-invasive and free of added reactants, they may be attractive for various water treatment practices including drinking water treatment.…”

Effect of Radical Species and Operating Parameters on the Degradation of Sulfapyridine Using a UV/Chlorine System

“…Li et al reported that sulfamethazine was degraded rapidly by the vacuum-UV/UV/chlorine process. 24 Guo et al observed that sulfamethoxazole degradation was also more efficient by the UV/chlorine process, and reactive chlorine species (RCS) plays a dominant role in the removal of sulfamethoxazole. 20 Such previous studies mainly focused on the degradation kinetics and contributions of • OH and RCS on the degradation efficiency of SAs under the UV/chlorine system.…”