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Abstract
Endocrine disrupting chemicals in the environment are widely implicated as a major cause of physiological abnormality in wildlife. Thus, it is crucial to better understand the fate and behaviour of potent endocrine disruptors, such as 17β-estradiol (E2), estrone (El) and ethinylestradiol (EE2). This research study has: (a) Developed assays for identifying estrogens in environmental matrices; (b) Determined estrogenic activity in aqueousand solidphasesofprimary,secondaryandtertiarysewagetreatment plants (STPs); and (c) Determined sorption behaviour of estrogens in wastewater and receiving environments. The development of solid phase and liquid extraction methods, coupled to gas chromatography-mass spectrometry, has enabled detection and quantification of low-level estrogens in STPs.
Removal efficiency of Hand E2 from wastewater in primary STPs was poor (~14% and ~4% respectively). Secondary treatment removed significantly greater El and E210ads (~85% and ~96%) and these were further reduced folloWing tertiary treatment to below limit of Quantification (<0.1 ng.L-1) EE2 was <0.1 ng.L-1 in all tested wastewater samples.
Secondary biosolids contained low-level estrogens, e.g., 9% Hand 1% E2 in waste activated sludge. EE2 also occurred at detectable levels in sludge. Suspended fine particulates in wastewater contained H , E2 and EE2, although actual levels varied between raw and treated effluent. Addition of NaCI caused particle aggregation and reduced levels of suspended estrogens in wastewater (containing 12% particles ≤1.5µm). Marine sediments near STP ocean outfall had 0.16-1.17 El, 0.22-2.48 E2 and <0.5 EE2 (ng/g).
Estrogens removal via secondary treatment is controlled by preferential partitioning to the solid phase, due to high solid content in wastewater and extensive contact time between pollutants and sludge. Removal rates during activated sludge treatment are mainly caused by both sorption and degradation. The inefficiency of primary treatment is attributed to preferential partitioning to the water phase.
Estrogens are not fully dissolved in waste water but are partially sorbed to fine particulates possessing colloidal characteristics; the high-strength ionic environment causes coagulation and aggregation of colloidal estrogens. Treated effluent released to marine waters undergoes particle aggregation, leading to eventual accumulation of estrogens in marine sediments. Modelling of the physico-chemical properties of estrogens provided generally robust predictions of their fate and behaviour, although results were inconsistent for biological treatments.