Removal of veterinary antibiotics, alkylphenolic compounds, and estrogens from the Wuluo constructed wetland in southern Taiwan

Abstract

This study investigated the treatment in the constructed Wuluo wetland, Taiwan, of 13 veterinary antibiotics, including five classes (tetracyclines, sulfonimides, chloramphenicol, fluoroquinolone, and dyes), five alkylphenolic compounds (nonylphenol di-ethoxylates [NP₂EO], nonylphenol mono-ethoxylates [NP₁EO], nonylphenol [NP], octylphenol [OP], and bisphenol A [BPA]), and three estrogens (17β-estradiol [E₂], estriol [E₃], and 17α-ethynylestradiol [EE₂]). The veterinary antibiotics oxytetracycline (OTC), ciprofloxacin (CIP), chloramphenicol (CAP), oxolinic acid (OXO), sulfamonomethoxine (SMM), and sulfadimethoxine (SDM) were detected in 7.1–96.4% of samples with concentrations varying widely from not detected to 552 ng/L. Removal efficiencies within different units of the wetland system exceeded 87% for OTC, CAP, SMM, and SDM, excluding those for IP and OXO, which were 72.1% and 43%, respectively. The other seven antibiotics (tetracycline [TC], enrofloxacin [ENR], chlortetracycline [CTC], sulfamerazine [SMR], sulfamethazine [SMZ], malachite green [MG], and leucomalachite green [LMG]) were all below detection limits in all samples. Additionally, detection rates were as follows: NP₁EO, 70.0%; NP₂EO, 70.0%; 4-n-NP, 72.9%; 4-OP, 50.0%; BPA, 81.3%; E₂, 52.1%; E₃, 57.1%; and EE₂, 31.3%. Concentrations of the alkylphenolic compounds were as follows: NP₁EO, ND-1092.7; NP₂EO, ND-643.7; 4-n-NP, ND-6812.3; 4-OP, ND-10400.1; and BPA, ND-1733 ng/L. Natural and synthetic estrogens E₂, E₃, and EE₂ in samples were found in the ranges of ND–907.4, ND–749.5, and ND–226.0 ng/L, respectively. Analytical results show that with the exception of EE₂ throughout the wetland system, target compounds were largely removed.

Keywords:

• Alkylphenolic compounds
• estrogens
• constructed wetland
• veterinary antibiotics