The paper compared the removal degrees of selected contaminants of emerging concern in water solutions during advanced oxidation processes such as H2O2, O3, UV and UV/TiO2. The processes were conducted for 10, 30 and 60 min. The influence of the oxidizing agent dose was also investigated. The tested micropollutants belong to the group of pharmaceuticals (benzocaine, akrydyne, carbamazepine, demecolcine, ibuprofen, diclofenac, caffeine), UV blockers (dioxybenzone), hormones (β-estradiol, 17α-ethinylestradiol, mestranol, progesterone), pesticides (triallat, triclosan, oxadiazon) and food additives (butylated hydroxytoluene). The concentration of those compounds in water matrixes before and after selected oxidation processes was determined by GC-MS analysis preceded by solid phase extraction. The highest removal rate of pharmaceutical compounds was observed during the UV/TiO2 process. The decomposition of hormones in this process exceeded 96% and the concentration of the UV filter dioxybenzone was reduced by 75%. Single UV irradiation was most effective during the decomposition of butylated hydroxytoluene, triallat and oxadiazon. Toxicological analysis conducted in post-processed water samples indicated the generation of several oxidation by-products with a high toxic potential. The occurrence of tested micropollutant derivatives was confirmed by chromatographic analyses. The identification of the formed compounds was performed based on the obtained mass spectra.
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Advanced oxidation processes are widely used in real water treatment technologies. Indeed, the implementation of the photocatalysis process requires the use of immobilized catalysts or separation of the catalyst from treated water suspension in a filtration process. On the other hand, the application of the ozonation process should be preceded by the choice of an appropriate ozone generation method. In general, all advanced oxidation processes can by transferred form a laboratory to an industrial scale. The choice of a suitable process is therefore closely related to the physico-chemical proprieties of the water matrix and the type of the pollutants removed. The choice also depends on the financial outlay.
The fact of using high-efficiency micro-cleansing technology in advanced oxidation processes leads to the formation of new derivatives and, at the same time, highly toxic oxidation products.
Do you think that the use of methods based on mechanical processes (eg, nanofiltration) or physicochemical (reverse osmosis, electrolysis ...) would not give a similar effect to this type of micro-infiltration?
Indeed, membrane separation processes, such as nanofiltration and reverse osmosis, do not lead to the formation of micropollutant degradation by-products. However, during the membrane processes, the feed stream is divided into two streams: the permeate (purified stream) and the retentate. Due to the high concentrations of retained contaminants, the retentate becomes another problematic stream that requires proper treatment. In my opinion, sequential water stream treatment processes, that based on advanced oxidation processes and membrane processes can provide a solution for both removing of the formed oxidation by-products and the treatment of the filtration retentate.