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Many micropollutants including hormones, pharmaceuticals and personal care products (PPCPs), are used daily in households for personal health and cleaning purpose. Wastewater discharged from onsite wastewater treatment system (OWTS), commonly known as septic systems, can be an important source of micropollutants in the environment. This study investigated the fate and transport of 17 micropollutants, including human excretion markers, hormones, and PPCPs in OWTS drainfields. Effluent samples were collected from a tank and leachate samples were collected from three replicate OWTS drainfields constructed in lysimeters (1.5 m length, 0.9 m wide, 0.9 m high). Each lysimeter contained stacked layers of sand-gravel (7.6 cm), natural soil (30.5 cm), and commercial sand (30.5), as per guidelines for construction of commercial drainfields. A drip tube with three emitters was placed on top of the sand layer to disperse 9L/d of effluent equivalent to maximum allowable rate of 3 L/ft2 per day. The drip tube was covered with 15 cm of sand and St Augustine grass was planted on the top and sides of lysimeters to mimic typical Florida residential drainfields. Over 8-months, 14 micropollutants in the effluent and 12 in the leachate samples were detected at variable concentrations. Lysimeters were destructively sampled at end of the study from different layers and locations. The presence of acetaminophen, carbamazepine, and sulfamethoxazole in the drainfields suggested that sorption was the key mechanism. The removal of many micropollutants was >85% within 60 cm deep drainfields, suggesting vadose zone processes such as sorption, transformation, and microbial degradation likely limited leaching of micropollutants. |