Ozonation mechanism of carbamazepine and ketoprofen in RO concentrate from municipal wastewater treatment: Kinetic regimes, removal efficiency and matrix effect

Abstract

A relatively important disadvantage of reverse osmosis (RO) application to municipal wastewater reclamation is related to management of a concentrated waste stream containing high levels of organic contaminants. The present study investigated ozonation performance of RO concentrate from municipal wastewater treatment in a stirred semi-batch reactor. In this work, carbamazepine (CBZ, as a representative of ozone-reactive micropollutants) and ketoprofen (KET, one of ozone-resistant organic chemicals) were selected as target micropollutants. The absence of dissolved ozone within the first 60 min corresponding to initial ozone demand (IOD) complement suggested that chemical reactions took place quite fast, and ozone mass transfer was considered as a limiting step. A complete elimination of CBZ and an excellent removal of KET were observed in this period, indicating that molecular ozone was a dominated oxidant responsible for the decomposition of the target micropollutants in RO concentrate containing initial dissolved organic carbon (DOC 0 ,~50.8 mg L −1 ). N90% of ozone-reactive CBZ was eliminated at a low ozone dose of 0.33 g consumed ozone per g DOC 0 . More ozone dose requirement for an equivalent removal of KET was ascribed to its low ozone kinetic rate constant below 10 L mol −1 s −1 . In addition, the presence of high contents of organic matters and alkalinity in RO concentrate exhibited pronounced effects on the degradation of KET because of a competition with oxidants. Overall, ozonation appeared to be a promising alternative for disposal of RO concentrate in terms of micropollutant removal. However, additional technologies should be followed to further enhance the degradation rate of organic matters for a zero liquid discharge treatment scheme.

Selected Micropollutants Removal from Municipal Wastewater

“…Deng [65] applied the ozonation process to investigate the ozonation performance of reverse osmosis (RO) concentrate from municipal wastewater treatment using semi-batch stirred reactor. In his work, the target micropollutant carbamazepine, was added to municipal secondary waste as RO feed at a concentration of 10 mg/l.…”

“…Ultimately, over 90% of carbamazepine was removed at a low ozone dosage of 0.33 grams of consumed ozone per gram of initial dissolved organic carbon (DOC). The RO concentrate contained initial DOC ~50.8 mg/l [65]. The degradation of carbamazepine by ozonation is associated with the carbon double bond a acked by molecular ozone [66].…”

Treatability of Wastewater Containing Reactive Yellow 145 Dyestuff by Ozonation Process

“…Even if there is an increase in the ozone dose, the amount of ozone dissolved in the wastewater may have reached saturation, so the increase in removal efficiency is gradually [38].…”

Efficacy of Bacillus subtilis BMT4i/Activated carbon composite for removal of diclofenac and carbamazepine from aqueous solution

“…To address this critical issue, several techniques have been effectively used for the removal of these contaminations including ozonation [6][7][8] , degradation by photo-Fenton process 9,10 , degradation by UV Irradiation 11,12 , the adsorption process [13][14][15] . Some of these techniques have major disadvantages where the contaminant generates several by-products, which are more toxic than the initial compound.…”