Using Ultraviolet Absorbance and Color To Assess Pharmaceutical Oxidation during Ozonation of Wastewater

Abstract

The reduction of ultraviolet (UV) absorbance at 254 nm (UV 254 ) and true color were identified as appropriate surrogates to assess the oxidation of six pharmaceuticals (i.e., carbamazepine, meprobamate, dilantin, primidone, atenolol, and iopromide) during ozonation of wastewater. Three tertiary-treated wastewaters were evaluated during oxidation with ozone (O 3 ) and O 3 coupled with hydrogen peroxide (O 3 /H 2 O 2 ). The correlation between pharmaceutical oxidation and removal of UV 254 was dependent upon the reactivity of each specific compound toward ozone, as measured by the second-order rate constant (k′′ O 3 ). Oxidation of compounds with k′′ O 3 > 10 3 M -1 s -1 correlated well (R 2 > 0.73) with UV 254 reduction between 0-50%. Oxidation of compounds with apparent k′′ O 3 < 10 M -1 s -1 resulted primarily from hydroxyl radicals and correlated well (R 2 > 0.80) with the UV 254 reduction of 15-65%. The removal of true color also correlated well (R 2 > 0.85) with the oxidation of pharmaceuticals during the ozonation of two wastewaters. These correlations demonstrate that UV 254 reduction and true color removal may be used as surrogates to evaluate pharmaceutical oxidation in the presence or absence of dissolved ozone residual during advanced wastewater treatment with O 3 or O 3 /H 2 O 2 . The use of online UV 254 measurements would allow wastewater utilities to optimize the ozone dose required to meet their specific treatment objectives.

Development of surrogate correlation models to predict trace organic contaminant oxidation and microbial inactivation during ozonation

“…The results from the bench-scale experiments were compared with an independent pilot-scale data set from the literature (Wert et al, 2009b) and three pilot-scale reactors associated with the current study. The ozone test matrices were comprised of five different sand-filtered effluents, one ultrafiltration filtrate, and one membrane bioreactor (MBR) filtrate.…”

“…Validation data are limited for some compounds since the study from the literature only included a subset of the target compound list, and some compounds were not detected in the ambient matrices. The Wert et al (2009b) study evaluated pilot-scale ozonation (1 L/min) of sand-filtered tertiary effluent from three different locations in the U.S. The ozone doses ranged from 0 to 12 mg/L (no H 2 O 2 addition), which corresponded to massbased O 3 :TOC ratios ranging from 0 to 1.2.…”

“…Buffle et al (2006) proposed the use of DUV to determine ozone exposure in wastewater applications after observing a first-order kinetic relationship between the two parameters. Based on this concept, Bahr et al (2007), Wert et al (2009b), and Nanaboina and Korshin (2010) developed preliminary correlations between DUV 254 and several indicator compounds and microbes. Bahr et al (2007) presented the linear regression parameters in relation to second-order ozone and OH rate constants.…”

“…Bahr et al (2007) presented the linear regression parameters in relation to second-order ozone and OH rate constants. Wert et al (2009b) indicated that ozone-susceptible target compounds (i.e., k O3 > 10 3 M À1 s…”

Combined Process of Ozone Oxidation and Ultrafiltration as an Effective Treatment Technology for the Removal of Endocrine-Disrupting Chemicals

“…The reduction of three-dimensional fluorescence spectra at excitation/emission wavelengths of 225-250/325-400 nm and 275-300/325-400 nm, and ultraviolet absorbance at 254 nm, 258 nm, 260 nm and 280 nm are proposed herein as potential surrogates to assess the removal of organic compounds. For example, ultraviolet absorbance at 254 nm can be used to evaluate the removal of aromatic components within organic compounds during ozonation [18]. The five typical EDCs selected as research objects were estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynyl estradiol (EE2), and bisphenol A (BPA).…”