Chemical and Biological Analyses of Selected Endocrine Disruptors in Wastewater Treatment Plants in South East Queensland, Australia

Abstract

Studies in North America, Europe, Japan and Australia have reported the presence of endocrine disrupting compounds (EDCs) in wastewater treatment plants (WWTPs) effluent could affect physiological and reproductive function in exposed fish consistent with exposure to hormonally active chemicals. The occurrence of EDCs in rivers and receiving environments situated near WWTPs raises concern over the removal efficacy of these compounds by conventional treatment processes. The main aim of this study was to utilize chemical analyses to assess concentrations of selected endocrine disruptors as well as a biological assay to measure the potential estrogenic effects of EDCs present in water discharged from wastewater treatment plants in South East Queensland, Australia. Currently, there are few reported studies on the estrogenic effects of EDCs released from WWTPs into receiving environments in Australia. Two field sampling methods were used. Grab sampling with subsequent extraction using a solid-phase extraction (SPE) technique and passive sampling utilizing EmporeTM (styrene-divinylbenzene copolymer) disk were used in this study. A gas chromatography-mass spectrometric (GC-MS) method was successfully developed to simultaneously analyze 15 environmentally ubiquitous EDCs including phthalates, alkylphenols, tamoxifen, androgens and estrogens. Application of these methods for the determination of target EDCs in wastewater samples in this study showed 80 – 99% removal of most EDCs from influent to effluent, despite the wastewater treatment plants having different treatment processes. It was observed that the passive samplers accumulated less EDCs than predicted when compared to the grab samples. This is probably caused by, but may not be limited to, biofouling, low flow rate, biodegradation and temperature which can progressively reduce the uptake of compounds into the sampler. A future challenge would be to improve the reliability of passive samplers by reducing or controlling the environmental conditions that may impact on the passive sampler performance. Stir bar sorptive extraction (SBSE) in combination with thermal desorption coupled to GC-MS was successfully applied to analyze a range of EDCs in wastewater, biosolids and sludge. The technique was shown to be very versatile, shortening extraction time, reducing sample volume needed as well as being sensitive for the analysis of a wide range of EDCs. The results showed that there were high amounts of phthalates, alkylphenols and female hormones present in the raw influent wastewater and biosolids of the WWTP samples. For the complimentary bioassay, a proliferation assay using human breast cancer cell line MCF-7 (E-Screen assay) was used to determine estrogen equivalents (EEqs) in grab and passive samples from five municipal WWTPs. EEq concentrations derived by E-Screen assays for the grab samples were between 108 – 356 ng/L for the influents and <1 – 14.8 ng/L for the effluents with the exception of one effluent sample which was at 67.8 ng/L EEq. In most wastewater samples, the natural estrogens contributed to 60% or more of the EEq value. Based on the chemical and in vitro biological analyses results and coupled with reported no observed effect concentration (NOEC) in vivo studies (mainly based on fish vitellogenin studies), the risk of EDCs found in effluents of the monitored WWTPs having a significant impact on the receiving environment is reasonably low. Furthermore, a fugacity-based analysis was employed to model the fate of selected industrial chemicals with endocrine disrupting properties in a conventional activated sludge WWTP. Using mass balance principles, a fugacity model was developed for correlating and predicting the steady state-phase concentrations, the process stream fluxes, and the fate of four phthalates and four alkylphenols in a WWTP. The relative amounts of chemicals that are likely to be volatilized, sorbed to sludge, biotransformed, and discharged in the effluent water was assessed. Results obtained by applying the model for the eight compounds compared satisfactorily with data from the WWTP. All eight EDCs modelled in this study had high removal efficacy from the WWTP. Apart from benzyl butyl phthalate and bisphenol A, the majority is removed via biotransformation followed by a lesser proportion removed through primary sludge. Fugacity analysis provides useful insight into compound fate in a WWTP and with further calibration and validation the model should be useful for correlative and predictive purposes. In conclusion, the complementary chemical and biological analyses used in this study provided a comprehensive assessment which showed that the EDCs discharged from the monitored WWTPs would be expected to have a low impact on the receiving environments.