wwtp brochure

8/3/2019 WWTP Brochure

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At present, the plant will treat, on average, 3 million gallons of wastewater per day. That's enough

flow to cover the playing surface of Beaver Stadium and fill it 7.5' deep. WOW!

Throughout this brochure, you will find many terms with which you might not be familiar. To help

you better understand these terms, a list of definitions is provided on page 4.

GRIT BUILDING

Flumes One and Two

Wastewater enters the plant through metering flumes from the State College Borough and University lines. The first

step in the treatment is to remove abrasive material called "grit," then remove non-biodegradable solids (plastics,

rags, etc.) contained in the influent by passing all incoming wastewater through a screen. Ferric chloride is thenadded to aide in the removal of phosphorus. The sewage is then equally distributed into three primary

aeration/settling tanks.

PRIMARY

SETTLING TANKS

First, the wastewater is aerated to prevent septicity. Then it flows into settling tanks. At this time, any solids in the

sewage are allowed to settle to the bottom of the tanks where they are pushed continuously into hoppers for periodictransfer to the digesters. Material that floats is also collected and transferred to the digesters for treatment. The flow

from the settling tanks, with most of the solid matter removed, is split, with a portion of flow going to the tricklingfilters and the remainder of flow going to the activated sludge plant.

TRICKLING FILTER

Number One

Trickling filters are not filters at all, but merely a large "pile of rocks." This "pile of rocks" provides a large surface

area for aerobic bacteria ("bugs") to cling to and feed on the organic waste in the settled effluent as it passes through

the filter. A rotary device, powered by the thrust of the liquids from the nozzles located along the length of the

distributor, spreads the settled effluent evenly over the filter bed. It then progresses to a quiescent zone in the final

settling tanks.

ANOXIC

TANK

Because we recycle our treated wastewater by irrigating farmland and forestland, we have a goal to minimize the amoun

of nitrogen in the water. We minimize the nitrate in our wastewater by nitrification (ammonia oxidation to nitrate) in th

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aeration tanks and denitrification (nitrate reduction to nitrogen gas) in the anoxic tank. This removal of nitrate in the

wastewater by converting it to nitrogen gas released to the atmosphere is called nitrification/denitrification.

SLUDGE

THICKENER

The sludge thickener uses the air flotation process to remove water from the sludge. This lessens the hydraulic load

on the digesters where the sludge is sent.

ACTIVATED SLUDGE

Units One and Two

The activated sludge process consists of two identical units. The circular tanks have an inner area used for aeration and

mixing of the biomass (a whole lot of bugs), and an outer quiescent zone for separation of the biomass by settling. The

settled solids are collected and removed from the bottom of the tank. The solids are recirculated back to the aeration

zone as seed or removed from the system as excess sludge (biomass) and sent to the sludge thickener. The clarified

effluent flows to the chlorine contact tank for chlorination. These tanks also provide nitrification/denitrification.

BLOWER AND

PUMP BUILDING

Pumps in the basement are used to recirculate sludge from the activated sludge tanks. The noise heard in the

background is caused by blowers supplying air to the activated sludge tanks.

CHLORINE

CONTACT TANKS

Chlorine is used to control bacteria before the final effluent is discharged. Remember that bacteria are critical for

the treatment process.

PRIMARY

DIGESTERS

The sludge digesters are anaerobic in that they utilize bacteria that thrive in a warm, 95°F, atmosphere in the absence

of oxygen. The action of these bacteria reduces the volume of the sludge with an end product of stable sludge,

methane gas and CO2. The methane gas is burned in a heater to keep the sludge warm, and the excess is flared. The

digestion process is carried on in two stages. The initial stage produces the digestion, and the second stage is used to

separate the sludge and water and provide storage space. The digested, thickened sludge is withdrawn from the

bottom of the secondary unit for disposal and sent to the belt filter press. A clear liquid called "supernatant" iswithdrawn from the top of the secondary digester and recycled throughout the plant. The digestion process requires

approximately 60 days to complete.

WASTE GAS

BURNER

The excess methane gas that is produced is flared at this burner.

BELT FILTERPRESS BUILDING

The thickened, digested sludge is pumped to a device called a "belt filter press." The filter press squeezes water out

of the sludge. The sludge is conveyed to the storage pad.

SLUDGE STORAGE

PAD

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This is where sludge is stored and air-dried prior to removal to a landfill. Presently, the sludge is disposed in a state-

approved double-lined landfill.

SOIL FILTER

This captures the atmospheric conditions in the large white domes of both trickling filters. Large blowers push air

through a mixture of mulch which removes the odors associated with this process.

FINAL SETTLING

TANK

These are the final settling tanks used to collect solids traveling from the trickling filter.

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What Happens Next?What Happens Next?Instead of being discharged into Spring Creek after chlorination, the treated effluent is pumped to the

spray irrigation sites. The sites sprawl over 516 acres on two tracts of land several miles north of the

campus, in the state gamelands, and near the University Deer Research Pens.

The "Astronomy" site, owned by the University, occupies 156 acres bounded by Fox Hollow Road on

the west and Sawmill Road on the south. On this tract, Living Filter land application experiments

began in 1962.

The "Gamelands" site was recently purchased by the University from the Pennsylvania Game

Commission and comprises 360 acres. It is situated directly north of the Toftrees residential

development.

On these two sites, approximately 60 miles of pipe have been installed. The system has over 3,000

sprayheads, through which the effluent is applied to fields and forests at planned intervals.

A maximum of 2 inches of treated effluent per acre per week can be sprayed on these sites. The rate

of application is about 1/6 inch per hour, which permits easy infiltration into the soil. In addition,

only about 7 percent - or 36 acres - of the total application area is sprayed at any one time.

List of Definitions

Advanced treatment:

A level of treatment that removes additional contaminants that have not been removed by secondary treatment.

Aeration:To supply a liquid with air by spraying the liquid to the air or bubbling air through the liquid.

Aeration tank:

A tank in which wastewater or other liquid is aerated.

Aerobic:

Living or active only in the presence of oxygen.

Anaerobic:

Living or active only in the presence of free oxygen.

Biochemical Oxygen Demand (BOD):

A measure of the quantity of oxygen used in the biochemical oxidation of organic matter in a specified time, at aspecific temperature, and under specific conditions.

Carbon dioxide (CO2):A heavy colorless gas that does not support combustion and is formed in animal respiration and in the combustion and

decomposition of organic substances.

Chlorine (Cl2):

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A nonmetallic chemical element that is found alone as a heavy, strong-smelling, greenish yellow irritation gas and is

used as a bleach, oxidizing agent, and disinfectant in water application.

Effluent:Water that flows from a treatment facility after the wastewater has been treated.

Methane:

A colorless, odorless flammable gas produced by decomposition of organic matter (as in marshes) or from coal and

used as a fuel.

Microorganisms:

Small living organisms, including bacteria. Some species consume the organic parts of sewage.

Oxygen (O):

A colorless, odorless gaseous chemical element that is found in the air, is essential to life, and is involved in

combustion.

Potable water:

Suitable for drinking.

Primary treatment:

The first stage of the wastewater treatment process at the facility in which mechanical procedures are used to remove pollutants.

Reclaimed water:

Effluent that is used for irrigation or other purposes.

Secondary treatment:

The second stage in wastewater treatment in which microorganisms consume the organic parts of the waste.

Supernatant:

The liquid remaining above a sediment or precipitate after sedimentation.

Wastewater treatment facility:

A structure with a series of tanks, screens, filters, and other processes used to clean wastewater before it is returned to

the environment.

Wastewater:Polluted water that has been used in homes, schools, businesses, and industries that is not suitable for reuse prior to

treatment.

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