Jump to main content
Jump to site search

Issue 5, 2019
Previous Article Next Article

Photodegradation of pharmaceutical compounds in partially nitritated wastewater during UV irradiation

Author affiliations

Abstract

The first step of an anaerobic ammonia oxidation (anammox) system is typically the formation of nitrite (NO2) via partial nitritation, which can generate hydroxyl radical (˙OH) when irradiated with ultraviolet (UV) light. This study demonstrated that the presence of nitrite in buffer and wastewater matrices during medium-pressure UV irradiation (at λ ≥ 220 or ≥ 280 nm) enhanced the degradation of select pharmaceutical compounds of different therapeutic classes (atenolol, carbamazepine, fluoxetine, and trimethoprim). Total pharmaceutical removals in a wastewater matrix irradiated at λ ≥ 280 for 120 minutes were 47% for trimethoprim, 50% for carbamazepine, 60% for atenolol, and 57% for fluoxetine at fluences of 58.6 mEi m−2 (2033.1 mJ cm−2). When irradiated at λ ≥ 220 for 60 minutes, removals were 52% for trimethoprim, 56% for carbamazepine, 69% for atenolol, and 90% for fluoxetine at fluences of 634.7 mEi m−2 (23 969.2 mJ cm−2). Reaction with ˙OH accounted for ∼78–90% of pharmaceutical removal at λ ≥ 280 nm. Although direct photolysis did contribute to target compound removal for irradiation with λ ≥ 220 nm, much of the light was absorbed in the buffer and wastewater matrices, and reaction with ˙OH accounted for ∼70–93% of pharmaceutical removal. Quencher experiments with isopropanol confirmed the importance of reaction with ˙OH as the main contributor to pharmaceutical removal. para-Chlorobenzoic acid was used as a probe to estimate steady-state ˙OH concentrations, which averaged 8.58 × 10−15 M for both matrices at λ ≥ 280 nm and 3.50 × 10−14 M for both matrices at λ ≥ 220 nm. Nitrosamines were formed and accumulated during the UV treatment step, however, concomitant with their direct photochemical destruction. Presence of the pharmaceutical micro-pollutants studied, such as the secondary-amine containing atenolol and fluoxetine, did not elevate nitrosamine formation.

Graphical abstract: Photodegradation of pharmaceutical compounds in partially nitritated wastewater during UV irradiation

Back to tab navigation

Supplementary files

Article information


Submitted
13 Oct 2018
Accepted
07 Mar 2019
First published
07 Mar 2019

Environ. Sci.: Water Res. Technol., 2019,5, 897-909
Article type
Paper
Author version available

Photodegradation of pharmaceutical compounds in partially nitritated wastewater during UV irradiation

P. I. Hora, P. J. Novak and W. A. Arnold, Environ. Sci.: Water Res. Technol., 2019, 5, 897
DOI: 10.1039/C8EW00714D

Social activity

Search articles by author

Spotlight

Advertisements