Upgrading treatment
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Major upgrades of treatment at Metro mean improved water quality in Onondaga Lake.
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The Metropolitan Syracuse Wastewater Treatment Plant (Metro) provides high quality treatment for
270,000 people and many industrial and commercial
customers in the City of Syracuse and some areas
outside the city in Onondaga County.
Metro treats an average of 84 million gallons per day.
Full secondary and tertiary treatment can be provided
for up to 126 million gallons per day. Metro has a total
hydraulic capacity of 240 million gallons per day
during wet-weather events such as rainstorms.
Project superlatives.
Construction photos
This $125 million state-of-the-art facility is
providing advanced treatment at Metro and reducing
levels of ammonia and phosphorus in the plant's
effluent to Onondaga Lake.
What do the latest data show?
The 2005 results are consistent with the trend of
improving conditions. Phosphorus and ammonia
concentrations have decreased to the lowest
concentrations ever measured in the lake over the 36
years of Onondaga County monitoring.
Concentrations of
dissolved oxygen have increased, and
algal blooms are diminishing. Improved water clarity
has allowed the beds of aquatic plants to
expand; this has provided improved nesting and nursery
habitat for the warm-water fish
community.
Improvements to the county's wastewater collection and
treatment system are primarily responsible for the
improved water quality conditions in the lake.
Significant public investment in wastewater treatment
technology has achieved far lower discharges of
wastewater-related pollutants, particularly ammonia
and phosphorus.
Dissolved oxygen has increased, algal blooms are diminishing. Improved water clarity has allowed the beds of aquatic plants to expand, providing improved nesting and nursery habitat for warm-water fish.
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.
Enhanced phosphorus removal from wastewater is another
objective of the Metro improvements currently
underway. A High Rate Flocculated Settling (HRFS)
physical-chemical treatment system (known as ACTIFLO)
was brought on-line in 2005 to reduce effluent total P
concentration. This stage of phosphorus treatment is
designed to bring effluent TP levels to meet a
12-month rolling average limit of 0.12 mg/L.
Compliance with this limit will be assessed beginning
in April 2006. The TP concentration in Metro's main
outfall (Outfall 001) in 2005 was reported at 0.195
mg/L. As a basis of comparison, the average Metro TP
concentration from 2000-2004 was 0.351 mg/L.
In 2005, Metro contributed about 43% of the total
external phosphorus load to Onondaga Lake through the
main outfall (38%) and the bypass (4.9%). The balance
of the external loading comes from nonpoint sources
throughout the large watershed. The magnitude of the
nonpoint sources varies each year depending on the
weather. The total loading from point and nonpoint
sources determines the in-lake concentrations. The
2005 lake phosphorus concentrations were the lowest
measured since Onondaga County began monitoring in
1969.
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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Advanced ammonia & phosphorus removal
Susan Miller, Project Deputy Director
Onondaga County Dept of Water Environment Protection