A filtration system has been designed to combat the release of 1,4-dioxane from onsite wastewater treatment systems to groundwater. The system developed by Stony Brook University researchers was tested in Long Island, New York, a region highly dependent on groundwater resources.

Different configurations of nitrifying sand beds coupled with denitrifying biofilters were applied to the capture of 1,4-dioxane from onsite wastewater treatment systems. The chemical is present in many household products and is highly resistant to biodegradation in conventional wastewater treatment systems.

The nitrogen removing biofilters consisted of a top sand layer and a bottom woodchip/sand layer and were demonstrated to remove both 1,4-dioxane and total nitrogen with an overall removal efficiency of 56 ± 20% and 88 ± 12%, respectively. Substantial quantities of total nitrogen were removed in the sand beds, likely due to denitrification in anoxic micro-zones.

Schematic of the nitrogen removing biofilter system. Source: Christopher J. Gobler et al./Stony Brook University

The filtration scheme described in Science of the Total Environment may help reduce the risk of contamination from residential septic and other onsite treatment systems to shallow aquifers. The research also confirms that biofilter installation can reduce 1,4-dioxane to levels even lower than the New York State drinking water standard of 1 μg/liter.