Application of a mechanistic UV/hydrogen peroxide model at full-scale: Sensitivity analysis, calibration and performance evaluation

Abstract

Numerous mechanistic models describing the UV/H 2 O 2 process have been proposed in literature. In this study, one of them was used to predict the behavior of a full-scale reactor. The model was calibrated and validated with nonsynthetic influent using different operational conditions. A local sensitivity analysis was conducted to determine the most important operational and chemical model parameters. Based on the latter, the incident UV irradiation intensity and two kinetic rate constants were selected for mathematical estimation. In order to investigate changes of the NOM content over time, some time delay was considered between calibration and validation data collection. Hydrogen peroxide concentration, the decadic absorption coefficient at 310 nm (UVA 310 , as a surrogate for natural organic matter) and pH could be satisfactorily predicted during model validation using an independent data set. It was demonstrated that quick real-time calibration is an option at less controllable full-scale conditions. The reactivity of UVA 310 towards hydroxyl radicals did not show significant variations over time suggesting no need for frequent recalibration. Parameters that determine the initiation step, i.e. photolysis of hydrogen peroxide, have a large impact on most of the variables. Some reaction rate constants were also of importance, but nine kinetic constants did show absolutely no influence to one of the variables. Parameters related to UV shielding by NOM were of main importance. At the conditions used in this study, i.e. H 2 O 2 concentrations between 0.5 and 4 mM, hydraulic residence times between 90 and 200 s and alkalinity concentrations between 2.5 and 6 mM, competitive radiation absorption by NOM was more detrimental to the micro pollutant removal efficiency than hydroxyl radical scavenging. Hydrogen peroxide concentration was classified as a non-sensitive variable, in contrast to the concentration of a micro pollutant which showed to be very to extremely influential to many of the parameters. UV absorption as a NOM surrogate is a promising variable to be included in future models. Model extension by splitting up the UVA 310

Kinetic model describing the UV/H2O2 photodegradation of phenol from water

“…In agreement with several authors [9,14,37], the decrease in DOC by means of direct photolysis (R 22 from Table 2) was obviated.…”

Prediction of key structural features responsible for aromaticity of single-benzene ring pollutants and their photooxidative intermediates

“…HO Å ). Additionally, the mineralization effectiveness can be simulated as well by including (simplified) degradation mechanism into the modeling formulation [17,18]. However, global water quality parameters related to biodegradability, toxicity, and aromaticity are more dependent on structural characteristics of formed intermediates thus may significantly vary during the treatment.…”

“…The effectiveness of UV-C/H 2 O 2 process, the most studied photochemical AOP, for the treatment of a vast array of organic pollutants, either simple-(e.g. single benzene ring) or complex-structured, is well documented [11][12][13][14][15][16][17], as well as its full-scale applications [18][19][20]. Since the complete mineralization of organic contaminants by AOPs might be costly, their application can be aimed at the elimination of targeted refractory organics (mainly of aromatic structures), thus increasing biodegradability and lowering toxicity and aromaticity of the treated water, which are often cross-correlated [21].…”

Fe3−Cu O4 as highly active heterogeneous Fenton-like catalysts toward elemental mercury removal

“…The Å OH radicals produced by Fenton-like reactions can oxidize and remove various pollutants with simple and secure process, low energy consumption, and no secondary pollution. During the past years, Fenton-like method has been widely applied for coal-fired flue gas cleaning Tan et al, 2007;Wang et al, 2010;Audenaert et al, 2011). Zhan et al (2013) developed a wet Ultraviolet (UV)/Fenton system to remove Hg 0 by setting a UV lamp into a lab-scale bubble reactor, and the oxidation process was enhanced by converting the insoluble Hg 0 into its soluble oxidized form and then removed by the wet scrubber.…”