1,4-Dioxane (1,4-D), a likely human carcinogen, is a widespread drinking water contaminant across the United States. Though primarily used as an industrial solvent, commercial household products such as shampoos, body wash and laundry detergents have been shown to contain very high (parts-per-million) levels of 1,4-D. As a result, its presence and release from domestic wastewater serves as an important and ongoing source of environmental contamination. Due to its resistance to biodegradation, 1,4-D is not effectively removed (&lt;30% removal) in conventional wastewater treatment systems (WTS) such as activated sludge treatment. In case of traditional on-site WTS (OWTS) such as septic tanks and cesspools, wastewater is directly discharged to the subsurface environment, increasing the risk of 1,4-D contamination in groundwaters. A combination of concentrated OWTS, sole-source aquifer (i.e. groundwater as the only source of drinking water), and elevated 1,4-D levels in groundwater, as observed in Long Island, NY, presents a unique challenge to prevent further contamination via wastewater discharges. In this study, we evaluated the performance of Nitrogen Removing Biofilters (NRBs) as OWTS, consisting of a top sand layer and a bottom woodchip + sand layer, to remove 1,4-D. NRBs have been demonstrated to reduce total nitrogen by &gt;90% in residential wastewater and have the potential to remove other organic contaminants given that they take advantage of naturally occurring microorganisms and feature long hydraulic retention time (several days). We monitored 1,4-D removal in two NRB systems installed at residences on Long Island, NY. Monthly samples of tap water at the residence, influent, interface, and effluent of NRBs were analyzed from November 2018 to September 2019. During this period, the mean 1,4-D concentration was 2.0 µg/L (range: 0.2~8.4 µg/L) in the influent and 0.6 µg/L (range: 0.1~2.6 µg/L) in the effluent, and the overall removal efficiency was 64±17%. Tap water was not the primary source of 1,4-D in these systems, confirming that 1,4-D originated from the use of household products. The majority of 1,4-D removal (~80%) occurred in the top oxic layer (nitrifying sand layer) of the NRB systems, implying that the removal was likely driven by aerobic microbial degradation. The results thus far show that NRBs can consistently reduce 1,4-D to levels lower than the proposed NY State drinking water standard of 1 µg/L.

Removal of 1,4-dioxane during on-site wastewater treatment using nitrogen removing biofilters

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.