Assessment of the endocrine disruption potential of an advanced tertiary treated sewage effluent using multiple lines of evidence
- Publication Type:
- Thesis
- Issue Date:
- 2010
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In Australia, due to increased uncertainties over security of water supply because of
unpredictable drought and flood cycles, alternative water sources are being investigated
for commercial, agricultural, industrial and domestic supply, including the option of
reusing treated sewage effluents. However, sewage effluent is a known source of
estrogenic endocrine disrupting chemicals (EDCs) in the environment. Exposure to
sewage effluents containing steroid estrogens and xenoestrogens can cause
developmental and behavioural reproductive abnormalities in fish and other aquatic
animals. As such, risk of endocrine disruption is one of the water quality issues that
needs to be evaluated when assessing the appropriate level of treatment required for
reuse applications. The Gerringong-Gerroa sewage treatment plant (GGSTP), currently
employs advanced tertiary treatment technology to treat domestic sewage from two
small coastal towns (Gerringong and Gerroa), which receive large seasonal influxes of
holiday makers. In this study, the efficacy of the treatment at the GGSTP in removing
estrogenically active chemicals was assessed using a multi-tiered assessment approach,
incorporating chemical analysis, in vitro bioassays and in vivo fish exposure studies.
The raw sewage influent was found to contain steroidal estrogens; 17βestradiol (E2),
estrone (E1) and estriol (E3) as well as synthetic phenolic xenoestrogens; 4-tertoctylphenol,
Bisphenol A and technical nonylphenol at concentrations commonly found
in sewage influents. The influent also displayed high levels of activity in the two-hybrid
yeast in vitro bioassay. However, the final effluent had no detectable concentrations of
steroidal estrogens, no estrogenic activity in the two-hybrid yeast assay and only
infrequent occurrence of low concentrations of synthetic phenols. Biodegradation by
activated sludge treatment provided significant, but incomplete removal of measured
EDCs and estrogenic activity, with the in-line combination of ozone oxidation and
biologically activated carbon filtration reducing the remaining estrogenic activity to
undetectable levels. EDCs in both the dissolved and particulate phases of the effluent
were removed by the treatment process and the efficacy of treatment was not
compromised by increases in influent flow during the peak holiday seasons. Treatment
of the effluent at the GGSTP was also successful at reducing retinoic acid receptor
(RAR) activity and genotoxicity to below detection limits and greatly reducing
arylhydrocarbon receptor (AhR) activity.
On-site real-time exposure tests using the mosquitofish (Gambusia holbrooki) and
rainbowfish (Melanotaenia fluviatilis) demonstrated that the final effluent did not elicit
up-regulation of vitellogenin, a well known biomarker of exposure to estrogenic EDCs.
Despite the presence of residual concentrations of E1 and the in vitro activity in effluent
after being processed through activated sludge treatment, clarification and
sandfiltration, vitellogenin up-regulation was not detected in fish exposed to this
partially treated effluent. Overall, the results provide evidence that the application of
advanced tertiary treatment technology to domestic sewage can produce a final effluent
that is unlikely to pose an endocrine disruption risk to the aquatic biota.
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