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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Water Management and Conservation Research » Research » Publications at this Location » Publication #323795
Title: Septic systems as hot-spots of pollutants in the environment: Fate and mass balance of micropollutants in septic drainfields

Author
item YANG, YUN-YA - University Of Florida
item TOOR, GURPAL - University Of Florida
item WILSON, P.CHRIS - University Of Florida
item Williams, Clinton

Submitted to: Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/7/2016
Publication Date: 6/14/2016
Citation: Yang, Y., Toor, G.S., Wilson, P., Williams, C.F. 2016. Septic systems as hot-spots of pollutants in the environment: Fate and mass balance of micropollutants in septic drainfields. Environmental Science and Technology. doi: 10.1016/j.scitotenv.2016.06.043.

Interpretive Summary: Approximately 25% of households in the United States use septic systems for treatment and disposal of sewage. Effluent discharged from septic systems can be an important source of micropollutants in the environment. The fate and transport of 17 micropollutants, including human excretion markers, hormones, pharmaceuticals and personal care products were investigated in a septic system. Water entering the septic drainfield contained 14 micropollutants and only 12 were present in the leachate from septic drainfields. Concentrations of most micropollutants in the leachate were low (<200 ng/L) and more than 85% of the present micropollutants were removed by the septic drainfields. Sorption to soil was the key mechanism for retention of 3 compounds (acetaminophen, carbamazepine, and sulfamethoxazole) while microbial degradation was responsible for reducing the other 11 compounds. The leaching of micropollutants indicates that septic systems are potential sources of micropollutants in the environment. Future research should focus on understanding the conditions that lead to micropollutant removal in septic systems so that design and operational parameters can be optimized to prevent contamination of the environment.

Technical Abstract: Effluent discharged from septic systems, also known as onsite wastewater treatment systems, can be an important source of micropollutants in the environment. We investigated the fate and transport of 17 micropollutants, including human excretion markers, hormones, pharmaceuticals and personal care products (PPCPs) in a septic system. Commercial septic drainfields were constructed in lysimeters (1.5 m length, 0.9 m width, 0.9 m height) and managed similar to the field practice. This study is a first attempt to determine the fate of micropollutants in the septic drainfields. We found 14 micropollutants in the effluent and 12 in the leachate from septic drainfields. Concentrations of most micropollutants in the leachate were low (<200 ng/L) because >85% of the added micropollutants were attenuated in the septic drainfields. We discovered that sorption was the key mechanism for retention of acetaminophen, carbamazepine, and sulfamethoxazole, while microbial degradation attenuated 11 micropollutants in the drainfields. The leaching of micropollutants indicates that septic systems are hot-spots of micropollutants in the environment and a better understanding of the fate and transport of micropollutants in septic systems will aid in minimizing environmental impacts. Future research should investigate transformation products of various micropollutants in the septic drainfields and shallow groundwater.