A multi-disciplinary assessment of endocrine disrupting chemicals, pharmaceuticals and personal care products in australia's largest inland sewage treatment plant and the molonglo/murrumbidgee effluent-receiving environment
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2015
Authors
Roberts, Jenna Elizabeth
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An important milestone in twentieth-century environmental science was the publication of several reports from the United Kingdom in the 1990's, showing reproductive abnormalities in fish living downstream of sewage effluent outfalls. These observations triggered an outpouring of research targeted at endocrine-disrupting chemicals (EDCs), pharmaceuticals and personal care products (PPCPs) in sewage treatment plants (STPs) and effluent-receiving environments. However, the Australian evidence base is still limited. Differences in demographics, sewage treatment methods, climate and hydrology make extrapolation from Northern Hemisphere data problematic. This multi-disciplinary study is targeted at Australia's largest inland STP and the Molonglo/Murrumbidgee effluent-receiving environment. Using a range of chemical, immunological, in vitro and ecotoxicological techniques, the following topics were investigated: a. The application of hydrochemical sewage tracers to quantify effluent mixing and dilution; b. Behaviour of selected EDCs and PPCPs during sewage treatment, and loads in the effluent-receiving environment in high- and low-flow conditions; c. Estrogenic biomarkers in wild European carp; d. Whole-sediment toxicity in freshwater invertebrates; and e. Screening-level quantification of ecological risk Major research findings were as follows: 1. The zone of influence of effluent discharge changed significantly according to flow conditions. In some cases, simple tools that require minimal capital outlay (such as chloride analysis and electrical conductivity monitoring) are adequate tools for quantifying effluent mixing. 2. Removal of estrogenic chemicals in the STP was consistently high; however, concentrations of the potent synthetic estrogen ethinylestradiol increased along the treatment train, and were low but biologically relevant in effluent (0.8 parts-per-trillion). Total estrogenic potency in effluent was consistent with a 'low hazard' rating. In vivo testing revealed no evidence of reproductive impairment or adverse health in carp or midges specifically related to effluent discharge; however, a degree of biological impairment was observed in the Murrumbidgee River, upstream and downstream of effluent inputs. 3. Monitoring PPCPs in two seasons showed that removal during sewage treatment was incomplete and highly variable. The pharmaceuticals venlafaxine, carbamazepine, diphenhydramine, propranolol and sotalol showed increases in concentration along the treatment train. Influent loads varied between seasons for the same compounds, in some cases substantially (up to 8-fold). This variability may be due to changing behaviour of metabolites en route to the STP, according to ambient conditions in the sewer. This may in turn influence the extent of removal of these compounds from the wastewater stream during treatment. Effluent loads to the Molonglo/Murrumbidgee Rivers were consistently highest for carbamazepine, venlafaxine and sotalol (up to 64 g/day). 4. Total in vitro glucocorticoid receptor (GR) activity showed relatively poor removal during sewage treatment. Progestagenic receptor (PR) activity was low in influent, but increased along the treatment train. GR and PR activity persisted in the Molonglo/Murrumbidgee receiving environment to 4+ km downstream of the effluent outfall. 5. Calculation of risk quotients (RQs) revealed that there is a potential ecological risk associated with loads of venlafaxine, carbamazepine, fluoxetine, diphenhydramine and progestagenic compounds delivered to the Molonglo/Murrumbidgee via effluent discharge. Further intensive investigation of environmental fate and effects is needed.
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