Researchers at Stony Brook University have introduced an affordable way to upgrade the many aging septic tank systems on Long Island, aiming to enhance drinking water quality significantly.
At the university’s Water Purification Technology Center, a team led by researcher Thomas Varley has designed a solution to combat the pressing issue of toxic nitrogen seeping from septic tanks into the groundwater—and, subsequently, into local streams, rivers, and bays.
Varley mentioned that they’ve developed a prototype capable of being retrofitted into existing tanks, featuring a unique chamber filled with wood chips that effectively removes nitrogen from wastewater before it seeps into the ground.
“Everything that exits the septic tank goes directly into the earth and ultimately contaminates drinking water and surface waters,” Varley explained.
He added, “We’re witnessing the impact of surplus nitrogen, such as decreased oxygen levels, which can lead to rampant algae blooms, fish deaths, shellfish poisoning, and toxic blue-green algae.”
This innovative creation not only surpasses existing purification systems but also extracts nearly 10 milligrams more nitrogen than the best tanks available today, according to Varley.
He noted that traditional septic systems can release about 80 milligrams of nitrogen per liter, sometimes even more.
Currently, the standard for modern low-nitrogen systems in Suffolk County is 19 milligrams per liter, while Stony Brook’s prototype consistently recorded levels below 10 milligrams per liter.
“Many people don’t realize how significant one household’s contribution can be. This approach will drastically decrease nitrogen pollution entering the groundwater,” Varley said.
Traditional septic tanks act as underground reservoirs where solid waste settles, grease floats, and liquid waste drains into a leach structure.
Low-nitrogen systems typically involve removing the old tank and installing new equipment, which requires extensive excavation. However, the team’s prototype can be set up through a manhole cover, allowing homeowners to retrofit the existing system without invasive digging.
The design transforms a conventional tank into multiple chambers. Wastewater first goes to a treatment chamber, then to a second chamber containing wood chips, where bacteria flourish. This second stage effectively reduces nitrogen at its source, thereby lowering pollution levels that affect groundwater and nearby waterways.
In Suffolk County, around 360,000 homes—approximately 75% of the county—depend on septic systems, while Nassau County has about 35,000 homes, with 90% connected to sewer lines.
If this technology gained widespread adoption on Long Island, Varley believes it would markedly decrease the nitrogen infiltrating water supplies.
Suffolk County Executive Ed Romaine has expressed openness to discussions regarding this technology, mentioning potential grant approvals for local initiatives.
Before the prototype can be eligible for local and state septic tank grants—facilitating a quicker rollout—Suffolk County must assess and approve its grant status. The cost of this inventive system remains unclear for now.
Romaine indicated that his administration is committed to tackling nitrogen issues threatening drinking water, bays, and rivers. “We are eager to explore these new discoveries and technologies,” he stated.
