Removal of pharmaceuticals and personal care products (PPCPs) from wastewater: A review.

The removal efficiency for 220 micropollutants was studied at the scale of a municipal wastewater treatment plant (WWTP) upgraded with post-ozonation followed by sand filtration. During post-ozonation, compounds with activated aromatic moieties, amine functions, or double bonds such as sulfamethoxazole, diclofenac, or carbamazepine with second-order rate constants for the reaction with ozone >104 M−1 s−1 at pH 7 (fast-reacting) were eliminated to concentrations below the detection limit for an ozone dose of 0.47 g O3 g−1 dissolved organic carbon (DOC). Compounds more resistant to oxidation by ozone such as atenolol and benzotriazole were increasingly eliminated with increasing ozone doses, resulting in >85% removal for a medium ozone dose (∼0.6 g O3 g−1 DOC). Only a few micropollutants such as some X-ray contrast media and triazine herbicides with second-order rate constants <102 M−1 s−1 (slowly reacting) persisted to a large extent. With a medium ozone dose, only 11 micropollutants of 55 detected in the ...

Elimination of organic micropollutants in a municipal wastewater treatment plant upgraded with a full-scale post-ozonation followed by sand filtration.

Fluoroquinolones and their metabolites are found in surface and ground waters, indicating their ineffective removal by conventional water treatment technologies. Advanced oxidation processes (AOPs) are alternatives to traditional water treatments. They utilize free radical reactions to directly degrade fluoroquinolones. This work reports absolute rate constants for the reaction of ciprofloxacin with several free radicals, OH, N 3 and SO 4 − as well as hydrated electrons. Pulsed radiolysis experiments showed that OH, N 3 and e aq − reacted quickly with ciprofloxacin, with bimolecular reaction rate constants of (2.15 ± 0.10) × 10 10 , (2.90 ± 0.12) × 10 10 and (2.65 ± 0.15) × 10 10  M −1  s −1 , respectively, while the SO 4 − radical appeared not to react with ciprofloxacin. Transient spectra were observed for the intermediate radicals produced by hydroxyl and azide radical reactions. Moreover, ciprofloxacin can be degraded rapidly using a typical advanced oxidation process, TiO 2 photocatalysis, with half-lives of 1.9–10.9 min depending upon pH values. Seven degradation products were elucidated by LC/MS/MS analysis, and the degradation mechanism of ciprofloxacin was also tentatively proposed by combining the experimental evidence with theoretical calculations of frontier electron densities. The calculations suggest that the addition of a hydroxyl radical to ciprofloxacin and photo-hole direct attack is two predominant reaction pathways.

Kinetics and mechanism of advanced oxidation processes (AOPs) in degradation of ciprofloxacin in water

Comparison between activated carbon, carbon xerogel and carbon nanotubes for the adsorption of the antibiotic ciprofloxacin

Adsorption of ciprofloxacin on surface-modified carbon materials

Degradation products formed during ozonation of an aqueous solution of the antibiotic ciprofloxacin in a bubble column are analyzed by HPLC-UV high-resolution mass spectrometry. Based on the identification of the reaction products, reaction pathways are proposed starting with (1) degradation at the piperazinyl substituent, (2) degradation at the quinolone moiety with formation of isatin analogues, and (3) degradation at the quinolone moiety with formation of anthranilic acid analogues. Unlike H2O2 addition (10 microM), pH (3,7, and 10) strongly affects degradation product formation during ozonation. Degradation at the quinolone core is favored at pH 7. Addition of t-butanol, a hydroxyl radical scavenger, ruled out formation of isatin and anthranilic acid analogues. Because the carboxylic group and the keto group at the quinolone moiety are essential for antibacterial activity, degradation at pH 7 seems to be promising for reduction of bacterial resistance against quinolones in contaminated water.

Vincent Van De Vyvere

Papers

Ozonation of ciprofloxacin in water: HRMS identification of reaction products and pathways.