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Exterior of ammonia-phosphorus treatment facility, October 2004
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Removing ammonia through advanced treatment
Onondaga Lake is a small waterbody that suffers from algal
blooms. To reduce these blooms and their adverse
effects, Onondaga County has added ammonia treatment to the
effluent of the Metropolitan Syracuse Wastewater Treatment Plant. This plant serves most of
Syracuse and many adjacent areas.
The County chose to use biological aerated
filters (BAFs) to lower ammonia in the effluent. The
technology is used extensively in Europe and
proved effective in a demonstration project
that the County completed.
 Testing ammonia treatment technology.
It is critical that the technology be effective
because Onondaga County's treatment goal is to reduce
ammonia to 2 mg/L during summers and to 4 mg/L in
winters. In the near future—the year 2012—the County
will further reduce ammonia, to 1.2 mg/L in the summer
and 2.4 mg/L in the winter.
Onondaga County submitted its ammonia report to NYSDEC on
June 29, 2007. The Amended Consent Judgment set submission of this report
as a major milestone for July 1, 2007. The report
summarizes the County's efforts and successes in
reducing ammonia in its Metro effluent to within both
Stage II and Stage III limits.
The completion and successful operation of the BAF
system to remove ammonia is the main reason why the
County has met the current and future ammonia limits.
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Southern half of the BAF gallery
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Eighteen new tanks were built for the ammonia
treatment. The tanks are filled with polystyrene
beads whose purpose is to expand the surface area of the
wastewater that is exposed to the treatment process.
Special bacteria in the tanks nitrify the nitrogen in
the ammonia. Here are a few facts about the ammonia
treatment:
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466 trillion biostyrene beads were installed in the eighteen BAF cells. Each bead is 3.6 millimeters (0.14 inch) in diameter.
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130,000 nozzles allow treated effluent to leave the cells while trapping the beads for continued use.
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Each of the eighteen BAF cell holds 273,000 gallons of water effluent, totaling nearly 5 million gallons.
Onondaga Lake has exhibited elevated ammonia
concentrations for decades. Monitoring results from
1970 to 2002 documented that ammonia levels in the
lake waters were above New York State's ambient water
quality standards designed to protect aquatic life.
Metro effluent was the largest source of ammonia to
the lake, averaging about 90% of the total annual
input. Recent improvements to Metro were designed to
reduce ammonia levels in the treated effluent and
bring the lake's water quality into compliance with
state standards.
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The final stage of the Metro improvements for ammonia
treatment came on line in early 2004. The Biological
Aerated Filter (BAF) system has resulted in year-round
nitrification (conversion of ammonia to nitrate) in
wastewater. Metro had reduced its annual discharge of
ammonia from an average of 1210 metric tons (MT) from
1990-1997, to an average of 521 MT from 1998 to 2003.
In 2004, the annual Metro ammonia discharge was
reduced to 152 MT as the BAF system came on line. In
2005 the Metro contribution fell to 21 MT. As of 2005,
Metro is no longer the largest source of ammonia N to
Onondaga Lake. Lake ammonia concentrations in 2005
were the lowest ever measured, and remained at safe
levels for even the most sensitive aquatic organisms.
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Susan Miller, Project Deputy Director
Onondaga County Dept of Water Environment Protection