Environmental Exposure Assessment of Fluoroquinolone Antibacterial Agents from Sewage to Soil

Abstract

The behavior of fluoroquinolone antibacterial agents (FQs) during mechanical-biological wastewater treatment was studied by mass flow analysis. In addition, the fate of FQs in agricultural soils after sludge application was investigated. Concentrations of FQs in filtered wastewater (raw sewage, primary, secondary, and tertiary effluents) were determined using solid-phase extraction with mixed phase cation exchange disk cartridges and reversed-phase liquid chromatography with fluorescence detection. FQs in suspended solids, sewage sludge (raw, excess, and anaerobically digested sludge), and sludge-treated soils were determined as described for the aqueous samples but preceded by accelerated solvent extraction. Wastewater treatment resulted in a reduction of the FQ mass flow of 88-92%, mainly due to sorption on sewage sludge. A sludge-wastewater partition coefficient (log Kd approximately 4) was calculated in the activated sludge reactors with a hydraulic residence time of about 8 h. No significant removal of FQs occurred under methanogenic conditions of the sludge digesters. These results suggest sewage sludge as the main reservoir of FQ residues and outline the importance of sludge management strategies to determine whether most of the human-excreted FQs enter the environment. Field experiments of sludge-application to agricultural land confirmed the long-term persistence of trace amounts of FQs in sludge-treated soils and indicated a limited mobility of FQs into the subsoil.

Occurrence and fate of eleven classes of antibiotics in two typical wastewater treatment plants in South China

“…The high concentrations of ofloxacin (1500-5800 ng/g) and norfloxacin (1820-5610 ng/g) in the present study are consistent with previous reports in other regions of China (Gao et al, 2012;Jia et al, 2012) and in Switzerland (Golet et al, 2003). Ciprofloxacin was another frequently detected compound, with its concentrations of 296-714 ng/g in the present study, but with its concentrations of 1700-2700 ng/g in Switzerland (Golet et al, 2003). The results further suggest that norfloxacin and ofloxacin are more frequently used than ciprofloxacin in China.…”

“…Such high concentrations in the sludge would have negative impacts on the environment if the sludge was applied on agricultural land, including effects soil microbial diversity, respiration and denitrification due to their antimicrobial activities (Chander et al, 2005;Kotzerke et al, 2011;Zielezny et al, 2006). The high concentrations of ofloxacin (1500-5800 ng/g) and norfloxacin (1820-5610 ng/g) in the present study are consistent with previous reports in other regions of China (Gao et al, 2012;Jia et al, 2012) and in Switzerland (Golet et al, 2003). Ciprofloxacin was another frequently detected compound, with its concentrations of 296-714 ng/g in the present study, but with its concentrations of 1700-2700 ng/g in Switzerland (Golet et al, 2003).…”

“…2 and Tables S6-S7). Similar concentrations have also been observed in the wastewaters of other WWTPs in China (Gao et al, 2012;Jia et al, 2012;Leung et al, 2012;Li and Zhang, 2010;Xu et al, 2007) and other countries (Golet et al, 2003;Karthikeyan and Meyer, 2006;Lindberg et al, 2005;Watkinson et al, 2007). However, ciprofloxacin was found at lower concentrations than those reported previously in other countries (Golet et al, 2002(Golet et al, , 2003Yang et al, 2005), or at the lower end of those concentration ranges in Hong Kong (Li and Zhang, 2010) and Sweden (Lindberg et al, 2005).…”

“…The predominant removal mechanism of the fluoroquinolones has been suggested to be adsorption onto sludge rather than biodegradation (Golet et al, 2003;Jia et al, 2012;Li and Zhang, 2010;Lindberg et al, 2006). The mass load of the fluoroquinolones in the raw sewage was Fig.…”

Excretion masses and environmental occurrence of antibiotics in typical swine and dairy cattle farms in China

“…These antibiotics (e.g. tetracyclines, fluoroquinolones and sulfonamides) could persist in the soils for a long time (Forster et al, 2009;Golet et al, 2003;Hamscher et al, 2002). Antibiotic residues in soil could be taken up by vegetables Hu et al, 2010), and affect soil microbial and enzyme activities (Liu et al, 2009;Underwood et al, 2011), thus resulting in negative impacts on the soil environment and human health.…”