Presence and Reduction of Anthropogenic Substances with UV Light and Oxidizing Disinfectants in Wastewater—A Case Study at Kuopio, Finland

Jenni Ikonen,Anna-Maria Hokajärvi,Marjo Niittynen,Ilkka T Miettinen,Ilpo Nuutinen,Eero Antikainen,Tarja Pitkänen

doi:10.3390/w13030360

Abstract

Anthropogenic substances are a major concern due to their potential harmful effects towards aquatic ecosystems. Because wastewater treatment plants (WWTPs) are not designed to remove these substances from wastewater, a part of the anthropogenic substances enter nature via WWTP discharges. During the spring 2019, the occurrence of anthropogenic substances in the municipal wastewater effluent in Kuopio, Finland, was analysed. Furthermore, the capacity of selected disinfection methods to reduce these substances from wastewater was tested. The disinfection methods were ozonation (760 mL min−1) with an OxTube hermetic dissolution method (1), the combined usage of peracetic acid (PAA) (<5 mg L−1) and ultraviolet (UV) disinfection (12 mJ/cm2) (2), and the combined usage of hydrogen peroxide (H2O2) (<10 mg L−1) and UV disinfection (12 mJ/cm2) (3). The substances found at the concentrations over 1 µg L−1 in effluent (N = 3) were cetirizine (5.2 ± 1.3 µg L−1), benzotriazole (BZT) (2.1 ± 0.98 µg L−1), hydrochlorothiazide (1.7 ± 0.2 µg L−1), furosemide (1.6 ± 0.2 µg L−1), lamotrigine (1.5 ± 0.06 µg L−1), diclofenac (DCF) (1.4 ± 0.2 µg L−1), venlafaxine (1.0 ± 0.13 µg L−1) and losartan (0.9 ± 0.2 µg L−1). The reduction (%) with different methods (1, 2, 3) were: cetirizine (99.9, 5.0, NR = no removal), benzotriazole (67.9, NR, NR), hydrochlorothiazide (91.1, 5.9, NR), furosemide (99.7, 5.9, NR), lamotrigine (46.4, NR, 6.7), diclofenac (99.7, 7.1, 16.7), venlafaxine (91.3, NR, 1.1), losartan (99.6, 13.8, NR). Further research concerning the tested disinfection methods is needed in order to fully elucidate their potential for removing anthropogenic substances from purified wastewater.

Highlights

Emerging anthropogenic pollutants are a permanent global challenge to freshwater quality and safety [1,2,3]
In Finland, the legislation does not require the removal of anthropogenic substances from wastewater before discharge into the environment and most of the treated wastewaters are discharged to the receiving waters without disinfection
The anthropogenic substances with detected concentrations over 1 μg L−1 in the wastewater are shown in Table 1, as well as the removal efficiencies for the chemicals with the tested disinfection methods

Summary

Introduction

Emerging anthropogenic pollutants are a permanent global challenge to freshwater quality and safety [1,2,3]. A major group of emerging pollutants in the aquatic environmental consists of pharmaceuticals [4]. After being used for human or animal medication [5], pharmaceuticals are mainly excreted in urine and faeces as such or as metabolites [6]. They are distributed in the environment via wastewater treatment plants (WWTPs) [7] where they pass through various treatment processes and, are transferred to the receiving waters. In Finland, the legislation does not require the removal of anthropogenic substances from wastewater before discharge into the environment and most of the treated wastewaters are discharged to the receiving waters without disinfection.

Methods

Results

Conclusion