The occurrence of antibiotics in an urban watershed: From wastewater to drinking water
Introduction
Emerging concern for chemicals such as pharmaceuticals (e.g. antibiotics, antidepressants, hormones) and personal care products (e.g. insect repellents, shampoos, and soaps) has spawned a new generation of water quality issues and resulting management implications. The literature is sparsely documented with reported cases of pharmaceuticals and personal care products from the early 1950s (Levin et al., 1952, Stumm-Zollinger and Fair, 1965), however it wasn't until the mid 1990s that focused research into the fate and consequences of such compounds commenced (Halling-Sørensen et al., 1998, Hirsch et al., 1999).
Antibiotics were recently classified as a priority risk group due to their high toxicity to algae and bacteria at low concentrations and their potential to cause resistance amongst natural bacterial populations (Hernando et al., 2006). Hence, antibiotics in surface waters have the potential to disrupt key bacterial cycles/processes critical to aquatic ecology (nitrification/denitrification) or agriculture (soil fertility) and animal production (rudimentary processes) (Costanzo et al., 2005, Kinney et al., 2006a, Kummerer, 2004). Antibiotics have been reported in hospital wastewaters (Kummerer, 2001, Lindberg et al., 2004), wastewater treatment plant (WWTP) effluents (Batt et al., 2006, Costanzo et al., 2005, Watkinson et al., 2007), WWTP biosolids (Kinney et al., 2006b), soil (Blackwell et al., 2004, Jacobsen et al., 2004, Kinney et al., 2006a), surface waters (Batt et al., 2006, Kolpin et al., 2002, Kolpin et al., 2004), groundwaters (Hirsch et al., 1999, Lindsey et al., 2001, Sacher et al., 2001), sediments (Capone et al., 1996, Kerry et al., 1996, Kim and Carlson, 2006), biota (Dolliver et al., 2007, Kong et al., 2007) and drinking water (Zuccato et al., 2000).
The objective of this study was to investigate the occurrence of 28 antibiotics in watersheds of South–East Queensland, Australia. While the list of investigated antibiotics is by no means exhaustive, it represents a number of key clinical and agricultural antibiotics used in Australia (TGA, 2003). South–East Queensland is currently (2007) the fastest growing area in Australia, supporting approximately 3 million people (SEQRWSS, 2005). Objectives of the South–East Queensland Regional Water Supply Strategy (SEQRWSS) currently include the provision of indirect potable reuse (IPR) of WWTP effluent of the region via the Western Corridor Recycled Water project, due for completion in late 2008 (WCRW, 2007). This study was conducted between February 2005 and July 2006 and will provide baseline information on the presence of targeted antibiotics in South–East Queensland surface waters and the presence of such compounds in the regional drinking water supplies.
Section snippets
Site selection
A total of 114 sites were sampled in this study between February 2005 and July 2006 to investigate the occurrence of antibiotics throughout the urban water cycle. Sites investigated included hospital wastewaters (3 sites), WWTP-influents (5 sites), WWTP-effluents (5 sites), environmental surface waters (81 sites) and drinking waters (20 sites) (Fig. 1). Hospital samples were collected from the largest regional hospital in the study area at the three discharge points to the main sewer. Five
Results
One or more antibiotics were found in over 90% of samples collected, with only the drinking water samples failing to record any antibiotics above detection limits (Table 2). Nine antibiotics were found to have overall detection frequencies above 50% (Table 2), with norfloxacin being the most frequently detected (72%) followed by sulfamethoxazole (68%), naladixic acid (66%), trimethoprim (65%), tylosin (64%), lincomycin, (60%), monensin (61%), clindamycin (58%), and roxithromycin (56%). Of the
Occurrence of antibiotics in hospital wastewater
Relatively high concentrations and frequencies of antibiotics were detected in hospital wastewater compared to other locations, further supporting the notion that hospitals are a contributor of antibiotics to WWTPs (Brown et al., 2006, Kummerer, 2001). The drug classes: β-lactam, quinolone, lincosamide, macrolide and sulphonamides were all detected, a direct reflection of their usage volumes (TGA, 2003). However, there was no significant correlation between concentrations and usage volumes (p =
Conclusions
This study has demonstrated that while WWTPs are not specifically designed for the removal of antibiotics, removal of greater than 80% from the water phase has been demonstrated. The implications of this cannot be fully understood until there is an increased understanding of potential effects at these low concentrations and also the potential presence and effects of degradation products. The effects of degradates is largely unknown and while it is generally thought that these metabolites are
Acknowledgments
The authors wish to acknowledge technical assistance provided by Lesley Johnston, Masooma Trout and the staff at the National Measurement Institute. This project was supported through an ARC Linkage Grant (LP0453-708) and in part by the Wastewater Program of the Cooperative Research Centre for Water Quality and Treatment (Project number 666003). The use of trade, firm, or brand names in this paper is for identification purposes only and does not constitute endorsement by the National Research
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