Treatment of Antibiotics in Wastewater Using Advanced Oxidation Processes (AOPs) | InTechOpen, Published on: 2017-05-03. Authors: Ayse Kurt, Berna Kiril Mert, Nihan Özengin, et

In this study, we investigated the effect of different radical scavengers on the nitrate and/or nitric acid (NO₃⁻ and/or HNO₃) formation chain in liquid while the dielectric barrier discharge plasma system (DBD) was used for ozone (O₃) generation. The effects of the excess concentration of each scavenger were studied individually. In addition, ultrapure water (UPW), tap water, and surface water samples were examined in the same condition. Due to the absence of scavengers in the UPW, we expected the highest NO₃⁻ formation in this experiment because all active species produced by the DBD system should have formed NO₃⁻. However, the obtained results were unexpected; the highest NO₃⁻ formation was obtained in the tap water at 385 ± 4.6 mg/L. The results can be explained by some compounds in tap water acting as a trap for radicals involved in chain reactions that form NO₃⁻ and/or HNO_3. The second highest result was obtained in the sodium hydroxide solution as 371 ± 4.9 mg/L, since the OH⁻ ions accelerated the decomposition of O₃ to its intermediates such as hydroperoxide (HO₂⁻), ozonide (O₃⁻), and hydroxyl radical (OH^•), and, by increasing radicals in the liquid, more chain reactions can be promoted that lead to the formation of NO₃⁻ and/or HNO₃. On the other hand, the quenching of radicals by scavengers such as carbonate ion and phosphoric acid and/or the long-term stabilization of O₃ as O₃ negatively affected the chain reactions that generate NO₃⁻ and/or HNO₃.

In most cases traditional and advanced treatment technologies transfers and concentrates the pollutants from one phase to other phase. However, nowadays, these concentrated flows containing heavy pollution are rapidly moving away from being manageable. In particular, membrane concentrate flows await immediate solutions to this issue. Electrodialysis Bipolar Membrane (EDBM) Processes are becoming a serious and potential solution technique for similar concentrate streams. In this chapter, principles and potentials of EDBM processes for the recycling or recovery of membrane concentrates are discussed.