Comprehensive study of endocrine disrupting compounds using grab and passive sampling at selected wastewater treatment plants in South East Queensland, Australia

Chemical (gas chromatography-mass spectrometry, GC-MS) and biological (E-Screen assay) analyses were used to determine the concentrations of 15 endocrine disrupting compounds (EDCs) and estrogen equivalent (EEq) in grab and passive samples from five municipal wastewater treatment plants (WWTPs) in South East Queensland, Australia. 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. The EDC concentrations and EEq values for the passive samples were several times lower than those of the grab samples: a decrease probably caused by, but not limited to biofouling, low flow rate, biodegradation and temperature which can progressively reduce the uptake of compounds into the sampler. At this stage, grab sampling is the most reliable method for field monitoring; nevertheless, passive sampler is a useful sampling tool but the method requires more research to ensure that the information obtained can be interpreted appropriately. Although alkylphenols and phthalates were detected at higher concentrations in the wastewater samples as compared to natural hormones, the environmental risk may be negligible as their estrogenic potencies are several orders of magnitude lower than that of the natural estrogens. In most wastewater samples, the natural estrogens contributed to 60% or more of the EEq value. Removal efficacy of most estrogenic and xenoestrogenic compounds from the conventional activated sludge or biological nutrient removal (BNR) WWTPs monitored in this study was in the range of 80-> 99%. The efficiency of the WWTPs in removing estrogenic activity was > 95%. The EEqs of the E-Screen and those calculated from the results of extensive chemical analyses using the estradiol equivalency factors were comparable for most of the WWTPs samples.     

Modelling of the fate of selected endocrine disruptors in a municipal wastewater treatment plant in South East Queensland, Australia

The aim of this study was to develop a fugacity-based analysis of the fate of selected industrial compounds (alkylphenols and phthalates) with endocrine disrupting properties in a conventional activated sludge wastewater treatment plant (WWTP A) in South East Queensland, Australia. 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 WWTP A. Input data are the compound's physicochemical properties, measured concentrations and the plant's operating design and parameters. The relative amounts of chemicals that are likely to be volatilized, sorbed to sludge, biotransformed, and discharge in the effluent water was determined. Since it was difficult to predict biotransformation, measured concentrations were used to calibrate the model in terms of biotransformation rate constant. Results obtained by applying the model for the eight compounds showed <40% differences between most of the estimated and measured data from WWTP A. All eight compounds that were modelled in this study had high removal efficacy from WWTP A. Apart from benzyl butyl phthalate and bisphenol A, the majority is removed via biotransformation followed by a lesser proportion removed with the 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.