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Identifying Toxic Chemicals and Keeping Our Groundwater Safe

Cwt nitrogen biofilter

New York State Center for Clean Water Technology reveals a novel approach to removing contaminants

Cwt nitrogen biofilter
Image depicting the ability of Nitrogen Removing Biofilters, developed by the New York State Center for Clean Water Technology at Stony Brook University, to reduce wastewater effluent levels to less than 10 mg N per liter.

Emerging research from the New York State Center for Clean Water Technology (CCWT) at Stony Brook University affirms household products as a likely source of the carcinogen 1,4-dioxane in wastewater, but also reveals a novel approach for removing this chemical and other contaminants before it enters groundwater.

The center has developed a series of innovative Nitrogen Removing Biofilters (NRBs) comprised of layers of natural products commonly found across Long Island: sand and woodchips. In a new paper published in the international peer-reviewed journal Ecological Engineering, scientists from the center demonstrate that their NRBs, installed in Massachusetts and New York, remove up to 80-90 percent of nitrogen from wastewater before it is discharged to ground.

“In 2015, we set a goal to develop a septic system that reduces nitrogen from wastewater to less than 10 milligrams of nitrogen per liter; with this publication we’re showing the world we’ve met that goal and can achieve nitrogen levels lower than any commercially available system,” said CCWT director Chris Gobler.

Founded in 2015, a prime mission of the center — a joint venture between the top-ranked School of Marine and Atmospheric Sciences and the Department of Civil Engineering — has been to solve the nitrogen overloading crisis in Long Island’s groundwater and surface waters by developing innovative and alternative onsite septic systems.

Excessive nitrogen has shown to cause harmful algal blooms, the loss of important aquatic habitats like seagrass meadows, and the collapse of shellfisheries like clams and scallops. High nitrate in drinking water is also a public health concern.

Beyond nitrogen, the center is also focused on the ability of NRBs to remove other contaminants of concern, including 1,4-dioxane. In addition to monitoring nitrogen, the center has been collecting samples from homes outfitted with NRB septic systems, specifically collecting tap water, representing water entering the homes; influent wastewater, representing sewage exiting homes and entering the NRBs; and effluent (treated wastewater) exiting from the NRBs before it enters Long Island’s drinking water supply.

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Chris Gobler, director of the New York State Center for Clean Water Technology (CCWT).

The paper, published this month in the international peer-reviewed scientific journal, Science of the Total Environment, demonstrated that while tap water samples have levels of 1,4-dioxane less than one part per billion (ppb) — the drinking water standard for New York State — levels of 1,4-dioxane in the wastewater leaving homes were consistently higher than tap water levels, peaking as high as eight ppb, and increasing by more than tenfold, on average.

The results also show that the treated wastewater exiting the NRBs were, on average, 56% lower than the wastewater leaving the homes and was usually less than one ppb.  These analyses hold two important discoveries: The increase in 1,4-dioxane concentrations in the wastewater exiting homes suggests household products and activity is an important source of 1,4-dioxane in wastewater, and the NRBs are cleaning the wastewater, reducing 1,4-dioxane concentrations to levels below the proposed state drinking water standard of one ppb.

The efficient removal of 1,4-dioxane from wastewater by the NRBs is a breakthrough finding, as the chemical 1,4-dioxane is extremely difficult to remove from contaminated water supplies, with advanced oxidation processes being one of the only reliable approaches. This has Stony Brook University scientists encouraged.

“The enrichment of 1,4-dioxane in water supplies by household activity and the ability of our NRBs to remove this extremely persistent, probably carcinogen has important implications for protecting water supplies,” said Gobler.

“The results are very surprising and at the same time encouraging as 1,4-dioxane is expected to resist natural degradation processes and are not removed efficiently by filtration. Our team is performing controlled experiments to understand the mechanism by which 1,4-dioxane is removed by NRBs”, added Dr. Arjun Venkatesan, the CCWT’s associate director for drinking water initiatives.

These results could soon have broad implications for Long Island. NRBs just completed the experimental testing phase in Suffolk County and have entering the County’s ‘piloting test phase’. Upon the collection of 12 more months of data, NRBs will earn provisional approval in Suffolk County at which point anyone will be able to install these systems in their home. Current state, county, and town grant programs allow such systems to be installed at little-to-no cost to homeowners.

New York State Department of Environmental Conservation Commissioner Basil Seggos said, “The studies announced today bolster New York’s aggressive approach of preventing water contamination from 1,4-dioxane by eliminating it in household and personal care products, providing extensive resources including $14.5 million to support the Center for Clean Water Technology, investigating and remediating potential sources of contamination, and committing record funding for clean water infrastructure to protect drinking water quality on Long Island and across the state.”

Adrienne Esposito, executive director of Citizens Campaign for the Environment (CCE), said, “This type of cutting-edge science will further efforts to protect drinking water and surface water from both 1,4-dioxane and nitrogen. Strong, enforceable policies based on good science is the only way we can to continue to protect our aquifer and water resources for future generations. I want to thank the team at Stony Brook for engaging in research that directly benefits public health and provides meaningful guidance for a cleaner, safer future.”

“Last year, I worked closely with other state representatives to pass legislation to restrict the levels of 1,4-dioxane that would be permissible in household products,” said New York State Assemblyman Steve Englebright, chair of the Assembly Environmental Conservation Committee. “This study demonstrates how important that legislation was and how critically important it is that we now move swiftly to implement the action imposed by that bill.”

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