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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 #338489
Research Project: The Use of Treated Municipal Waste Water as a Source of New Water for Irrigation

Location: Water Management and Conservation Research

Title: Do septic systems contribute micropollutants and their transformation products to shallow groundwater?

Author
item YANG, YUN-YA - UNIVERSITY OF FLORIDA
item TOOR, GURPAL - UNIVERSITY OF FLORIDA
item WILSON, PATRICK - UNIVERSITY OF FLORIDA
item Williams, Clinton

Submitted to: Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2017
Publication Date: 6/21/2017
Citation: Yang, Y., Toor, G., Wilson, P., Williams, C.F. 2017. Do septic systems contribute micropollutants and their transformation products to shallow groundwater? Environmental Science and Technology. 123:258-267.

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 20 micropollutants, including wastewater markers, hormones, pharmaceuticals and personal care products, and their transformation products were measured from ground including human excretion markers, hormones, pharmaceuticals and personal care products were investigated in three different septic systems. Reduction of micropollutants were similar among three septic systems and ranged from 8% to more than 99%. However, concentrations ranging from <0.3 to 32,000 ng/L reached shallow groundwater. The human health risk assessment showed that the risk to human health due to drinking the groundwater is negligible.

Technical Abstract: Septic systems may contribute micropollutants to shallow groundwater and surface water. We constructed two in situ conventional drainfields (drip dispersal and gravel trench) and an advanced drainfield of septic systems to investigate the fate and transport of micropollutants to shallow groundwater. Unsaturated soil-water and groundwater samples were collected, over 32 sampling events (January 2013 to June 2014), from the drainfields (0.31 m) up to groundwater (3.1–3.4 m). In addition to soil-water and groundwater, effluent samples from the septic tank were also analyzed for 20 selected micropollutants, including wastewater markers, hormones, pharmaceuticals and personal care products (PPCPs), and their transformation products. The removal efficiencies of micropollutants were similar among three septic systems and were 8 – 43% for sucralose and 42–>99% for other micropollutants depending on the drainfield and micropollutants properties. Even with high removal rates within the drainfields, six PPCPs and sucralose with concentrations ranging from <0.3 to 154 ng/L and 121 to 32,000 ng/L reached shallow groundwater, respectively. The human health risk assessment showed that the risk to human health due to the drinking of groundwater is negligible. However, a better understanding of long-term ecotoxicological effects of micropollutant mixtures from septic systems to ecosystem and human health is warranted.