Stamford will receive money for nitrogen reduction

By Magdalene Perez
02/16/2009; The Advocate, Norwalk, CT

STAMFORD — The city’s wastewater authority earned a record $939,510 in nitrogen credits for 2008 under the state’s credit trading program.
The program requires sewage treatment facilities to buy or sell credits based on how effective they are at removing nitrogen from sewage during treatment. If a treatment plant discharges more nitrogen than its share of the state limit, it must buy credits at $4.50 per pound of nitrogen per day.
Statewide, 30 "over-performing" plants earned $2.7 million in credits, while 49 municipalities that did not meet state regulations will be required to purchase $6.1 million in credits. Waterbury earned the second highest credits at $349,853, followed by Bridgeport at $258,283. The worst performer, Stratford, must purchase $1,093,872 in credits, according to a draft report provided by the state Department of Environmental Protection.
Greenwich earned $167,535 in credits; Norwalk, $170,820; and Westport, $85,164.
The program’s goal is to prevent excess nitrogen found in wastewater from encouraging the growth of harmful algae in Long Island Sound, said Jeannette Brown, executive director of the Stamford Water Pollution Control Authority.
Nitrogen acts as a fertilizer to phytoplankton, microorganisms that can block sunlight from other plants. When phytoplankton die, they use up oxygen in the water, suffocating fish and other water animals. The environmental problem of very low levels of dissolved oxygen in the water is known as hypoxia.
To help stop hypoxia, Connecticut began the Nitrogen Credit Exchange in 2002. By reducing permitted levels each year, the program aims to reduce the amount of nitrogen discharged into the Sound by 65 percent by 2014.
Stamford has reduced its nitrogen levels to the 2014 goal, releasing less than 48 percent of the amount allowed under the statewide permit, Brown said and city officials said. Overall, the water treatment plant kept more than 200,000 pounds of nitrogen out of the Sound.
A $105 million upgrade to the city’s treatment plant in 2005 made the reductions possible, according to a statement released by Mayor Dannel Malloy.
"We made the investment in the treatment plant because it was the right thing to do for Long Island Sound," Malloy said. "But it is very gratifying that we have a system in place that rewards us for being so proactive in keeping nitrogen out of our waters."
The Water Pollution Control Authority owes about $65 million to the Connecticut Clean Water Fund for the upgrade, which costs about $4.5 million annually in debt service.
The money Stamford receives from the state for its credits will help reduce the amount Stamford residents pay in user costs for debt service, operating and maintenance, Brown said. She said she could not yet estimate how large the reduction would be to each user. Regulations require the state to pay the money directly to the authority, she said.
"We’ll actually get a check in August for $939,510," Brown said.
She said the new system uses microorganisms to convert ammonium, found in wastewater, to nitrate. Then another group of organisms converts the nitrate to nitrogen gas, which the plant releases into the air. The effect is harmless, Brown said, because air is naturally about 80 percent nitrogen, and the amount the plant releases is "infinitessimal" in comparison.
"You’re not creating an air pollution problem while you’re solving a water pollution problem," Brown said. "That’s pretty much the state of the art, every nitrogen removal plant does it biologically now."
Stamford received the highest amount of credits in 2007 as well, with $681,119.

— Staff Writer Magdalene Perez can be reached at or 964-2240.