>> Every day we wash our hands, clothes, and dishes. We take
showers and flush the toilet. But how often do we stop to
think about what happens next? Where does that water go?
Hi.
My name is Melissa. Welcome to the virtual tour of Fairfax
County's Noman M. Cole Jr. Pollution Control Plant.
During this tour we will show how our wastewater treatment
plant helps make your dirty water (or sewer water) clean by
removing pollutants before our reclaimed water is returned to
the local waterways.
Before we begin the tour, let me tell you a little about
Fairfax County's Noman Cole treatment plant.
Fairfax County's Wastewater Management Program maintains
over 3,300 miles of gravity sewer pipes and 63 waste water
pump stations located throughout the county. These
pipes and pump stations move wastewater from their homes and
businesses to one of the region's 5 advanced wastewater
treatment plants. Noman Cole is an advanced treatment plant
with the capacity to receive 67 million gallons of wastewater
per day. This is enough to fill 90 Olympic sized swimming
pools!
On average, we receive and treat about 40 million gallons
of wastewater per day from nearly 265,000 residential,
commercial, and industrial customers located in the
southern part of Fairfax County. Our wastewater
management system, and team of dedicated professionals,
work 7 days a week, 24 hours a day, And 365 days a year.
A critical task to providing reliable sewer service to the
residents of Fairfax County and protecting water quality,
human health, and the environment.
>> hard hat, safety
vest, long pants, sturdy shoes. Looks like we're ready! Let's
go.
>> Welcome to our first treatment process. Behind me
are the bar screens. This is where untreated wastewater
arrives at the treatment plant.
Here, wastewater passes through bar screens that collect and
remove trash, large objects, and debris that could damage
equipment in the treatment plant. This includes items that
are improperly disposed of down toilets and sinks, and do not
disintegrate or dissolve in wastewater. Once collected,
the trash and debris are mechanically raked onto a
conveyor system, dewatered, and collected in a dumpster that
sends it to the landfill.
After passing through the bar screens, the wastewater
continues to our primary clarafiers, which are large
settling tanks where heavier items settle to the bottom as
sludge and lighter items such as fats, oils, and grease float
to the top as scum. Once settled, an automated belt
skims the scum and sludge from the tank, sends it through
solids processing where it is then treated in the onsite
furnace.
These are the first processes for treating wastewate. Both
processes use an enclosed environment and have an
associated odor control system. This is a very important part
of the process for us and the surrounding community.
These processes also remove fats, oils, grease, and wipes
even those labeled as flushable.
These can clog and damage wastewater systems.
This results in sanitary sewer emergencies, like backups into
homes and overflows into the environment. You can help by
disposing of these items in the trash.
The wastewater now enter our secondary treatment. This is a
biological process where we use microorganisms that are so
small they cannot be seen with the naked eye. The
ASTs are a biological nutrient removal system. They remove a
significant amount of nitrogen, as well as phosphorus and
organic matter.
In these tanks, wastewater move between 2 zones: the aerobic
zone where oxygen is added, and anoxic zone where no free
oxygen is added. This is what makes the tanks look different
at one end versus the other
end. After multiple passes through these zones, the
microorganisms have been so effective in removing waste,
which
they use as food, that we need to add supplemental carbon to
the system as another food source to keep them alive.
After the ASTs, wastewater continues to the secondary
clarifiers, another step in the process. But this time we are
removing solids and microorganisms. Some of the
settled microorganisms are returned to the ASTs to start
the process again.
In some places, wastewater treatment ends at the secondary
treatment. This was true for Noman Cole when it went online
in 1970 and only had the capacity to treat 18 million
gallons of wastewater a day.
But if treatment may end here, the water should start to look
cleaner, right? Look at the muddy water entering the
clarifiers, and then how clear the water looks going over the
weirs to the next step of the treatment. Those microorganism
do a great job!
We can see the critical role microorganisms play in treating
wastewater. Improper disposal of household hazardous waste
down the drain can potentially harm the microorganism
populations and the quality of our final effluent.
So, if it's toxic, corrosive, ignitable, reactive,
safely pack these items in a box. Take them to the household
hazardous waste facility for proper disposal.
After secondary treatment, wastewater is sent to retention
ponds before starting our advanced treatment process.
Why do we use retention ponds at this point? Well, the final
2 treatment processes operate most efficiently when a
constant flow is maintained.
From the retention ponds, wastewater is pumped to the
moving bed biofilm reactor where we start advanced
treatment. This biological process uses a small plastic
media in the shape of pasta wheels, microorganisms, and
supplemental carbon to further lower nitrate and nitrite
levels and ultimately produce a higher quality final effluent.
The plastic media increase the surface area for microorganisms
to live and form small colonies referred to as biofilm. The
supplemental carbon is their food source.
From the moving bed biofilm reactor, wastewater enters the
tertiary clarifiers, where the chemical Ferric chloride is
added to remove pollutants in a process called chemical
floculation. Ferric chloride naturally attracts phosphorus,
microorganisms, and other solids which form flock.
They become heavier and settle to the bottom of the tank.
The settled sludge sent back to the head of the plant to start
the treatment process again, and the treated wastewater
continues to our final treatment process.
Final treatment includes filtration and disinfection to
remove particulate and microorganisms. As wastewater
flows into the filtration system, suspended solids and
microorganisms are removed. It passes through a
disinfection process to eliminate microorganisms prior
to discharging our final effluent into Pohick Creek.
Disinfection can be obtained through chlorination
dechlorination process or ultraviolet light. Since
beginning operations in 1970, Noman Cole used chlorine for
this process.
In early 2021, we are converting our disinfection
process to ultraviolet light. This process improvement
instantly neutralizes any remaining microorganisms with
ultraviolet light and significantly reduces the
chemicals used.
This completes the treatment process. It takes about 24
hours from the time wastewater enters the plant until the time
it is discharged. So,
how do we know that our final effluent is safe for aquatic
life in Pohick Creek?
We have an on site accredited state of the art environmental
monitoring laboratory that analyzes samples from all
stages of the treatment process to ensure each plant process is
running efficiently and that our final effluent meet
regulatory requirements.
Also, our plant operators, warehouse staff, mechanics,
instrumentation technicians, electricians, maintenance
crews, environmental technologists and
administrative personnel work together as a team leading us
to decades of success within the Wastewater Management
Department.
Fairfax County Wastewater Management is committed to
protecting, restoring, and enhancing the environment,
and ensuring there is fresh accessible water for
generations to come.
Fairfax County, with assistance from GMU, has been monitoring
water quality and acquatic life in Gunston Cove for 35 years.
Throughout the study, GMU and Fairfax County have documented
significant improvements to water quality and aquatic
ecosystems of the cove. The Water Reuse Project uses
reclaimed water for irrigation and industrial purposes.
This helps save drinking water and reduces pollutants such as
nitrogen and phosphorus from entering our rivers and
streams.
Flood walls have been incorporated to keep
surrounding creek water out, prevent flooding, and protect
the treatment process.
Since 2012, the plant has participated in the PJM
Emergency Response Program that provides relief to the
electrical grid and helps curtail energy use doing
emergency events. This resulted in the installation of new
generators capable of powering all wastewater treatment
operations.
Noman Cole continuously looks for ways to improve processes,
reduce our carbon footprint, and show environmental
stewardship. Noman Cole has received the Platinum Peake
Performance award for 22 years of continuous permit
compliance, maintained certification as an E4
participant in the Virginia Environmental Excellence
Program, and is recognized with the Utility of the Future
Award.
You can also help protect the environment. Remember to throw
trash in the trashcan. Keep
the fats, oils and grease and household hazardous waste out
of your drains and only flush human waste and toilet paper.
Thank you for watching our virtual tour. For more
information visit our website.
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