Estrogens are steroid hormones that are excreted by vertebrates and act as potent endocrine-disrupting compounds. The primary source of introduction into the environment is through raw and treated sewage. Treatment with hypochlorite is often used to disinfect wastewater effluent before it is discharged. However, this process forms halogenated forms of estrogens, mainly chlorinated and brominated forms.<br/>Effluent was collected before chlorination at Willow Lake Water Pollution Control Facility in Salem, OR. Batch experiments (25mL) were spiked with 17β-estradiol (E2) and sodium hypochlorite was added at a representative concentration. Aliquots (1mL) were removed over 1 hour and analyzed using liquid chromatography coupled with a mass spectrometer (ABSciex QTRAP4000). A model for halogenation kinetics was constructed in MATLAB.<br/>Small batch reactions of E2 with hypochlorite yielded monoClE2, diClE2, and monoBrE2. The model and the batch reactions agreed in the following ways: E2 decreased &gt;95% over 60 minutes; monoBrE2 was formed and reached its maximum concentration in &lt;10 min; monoClE2 and diClE2 degrade on similar timescales. The model accurately predicts the maximum concentrations of monoClE2, diClE2, and monoBrE2.<br/>The rates of photolysis for halogenated estrogens occur on a timescale of &gt;1 hour. Photolysis parameters will be included in the model to provide a better representation of the behavior of halogenated estrogens through the disinfection basin. Model results will be compared to estrogen concentrations in final treated effluent.

Modeling the formation and fate of halogenated estrogens

2019 Spring National Meeting

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