Preliminary & Primary Treatment

Front 1

What device is more commonly used for separation of grit slurry?

Back 1

Cyclone classifier

Hint 1

These devices basically spin the grit out of the slurry using centrifugal force.

Your score is 100%.

Front 2

What does H2S turn into that causes the damage to concrete and metal?

Back 2

Sulfuric acid

Hint 2

It's the acidic condition from the sulfuric acid that causes damage to concrete and metal.

There once was a chemist ... a chemist no more ... thought he drank water ... but drank H2SO4

Front 3

What is the guideline velocity number for proper grit removal?

Back 3

1.0 fps

Hint 3

Less than 1.0 fps (feet per second) will also remove organic material with the grit, and create odors in the storage container. Greater than 1.0 fps may allow grit to pass through the grit chamber.

Your score is 100%.

Front 4

Which chemical is typically used for wet scrubber odor control at the solids handling portion of a plant?

Back 4

Acid

Hint 4

Solids handling odors are mainly ammonia based. It typically requires low pH to accomplish absorption in a wet scrubber treating odors from a solids handling process (especially with anaerobic digestion).

Front 5

Aerated grit chambers usually utilize what type of aeration system?

Back 5

Diffused

Hint 5

The diffusers are typically located along one side of the tank creating a rolling action across the tank's width.

Front 6

Grit is mainly:

Back 6

Inorganic material

Hint 6

This material does not provide any food value to the biology and only takes up valuable tank space. It is essential to remove grit from the raw wastewater to protect pipe elbows, pump impellers and other internal surfaces from pitting and erosion.

Front 7

What is H2S?

Back 7

Hydrogen sulfide

Hint 7

Hydrogen peroxide is H2O2. Sulfuric acid is H2SO4.

Front 8

What method of grit removal is the Pista Grit system?

Back 8

Forced vortex

Hint 8

Forced vortex means that it has a mechanical paddle drive system to create the vortex action. Free vortex uses the entry angle to create a vortex without any moving equipment.

Front 9

Which chemical is typically used for wet scrubber odor control at the headworks of a plant?

Back 9

Sodium hydroxide

Hint 9

Headworks odors are mainly H2S based. This requires a high pH to remove the sulfides. Sodium hydroxide (caustic) is the only chemical on the list that is capable of increasing the pH necessary for absorption of H2S in a wet scrubber.

Front 10

Typical primary clarification removes TSS in which range?

Back 10

40 to 60%

Hint 10

One of the main purposes of primary treatment is to allow the downstream biological treatment process to be down-sized ... due to the removal of TSS and CBOD5 from the influent wastewater.

Typical removal efficiency for CBOD5 is about 25 to 30% of the influent wastewater.

Front 11

What is the basic purpose for the screenings removal process?

Back 11

To protect downstream pipes, pumps, valves, and other components from plugging.

Hint 11

Screenings removal is essential to maintain maximum operational capacity of pumps and pipes.

Front 12

Screenings debris is mainly:

Back 12

Organic material

Hint 12

Most material captured and removed by a bar screen is organic ... volatile.

Front 13

What adjustment is generally necessary when gas and/or solids rise to the surface of a primary clarifier?

Back 13

Increase the amount of primary sludge withdrawal

Hint 13

Gas and rising sludge in a primary clarifier is usually caused by anaerobic conditions in the sludge blanket.

Increasing the amount of sludge removed from the clarifier will help to reduce the production of anaerobic gases.

Front 14

Where is a typical location to pump primary sludge?

Back 14

Anaerobic Digestion

Hint 14

Most plants with primary clarifiers also have anaerobic digestion to accomplish stabilization of the primary sludge.

Front 15

What does this formula represent?

(IN - OUT) ÷ IN x 100 = %

Back 15

Removal efficiency

Hint 15

This formula will calculate removal efficiency of most constituents ... TSS, CBOD5, TN, TP, etc.

Front 16

Is H2S lighter or heavier than air?

Back 16

Heavier

Hint 16

Hydrogen sulfide has a higher specific gravity (1.192) as compared to air (1.0). That's why H2S settles to the bottom of a space.

Front 17

Which principle does the wet scrubber use for odor control?

Back 17

Absorption

Hint 17

The odors are basically "soaked" into and held in the liquid stream ... like water soaks into a sponge. This usually requires a pH of at least 9.0 to 10.0 to accomplish absorption of H2S in a wet scrubber.

Front 18

What does SOR mean (associated with primary clarification)?

Back 18

Surface overflow rate

Hint 18

This measures the number of gallons per day that are applied to the clarifier for every square foot of the clarifier surface area (gpd/ft2)

Front 19

A screenings removal unit with less than ½ inch openings is known as:

Back 19

A fine bar/filter screen

Hint 19

These units are typically automated and controlled by timers or differential head across the screen.

Front 20

What is a typical range for an SOR within a primary clarifier?

Back 20

800 to 1,000 gpd/ft2

Hint 20

Hydraulic loading rates are typically higher in primary clarifiers than secondary clarifiers.

Front 21

What does H2S smell like at high concentrations?

Back 21

No smell

Hint 21

There is no smell because the high concentration of H2S basically deadens the sense of smell (olfactory fatigue).

Front 22

Which principle does the activated carbon system use for odor control?

Back 22

Adsorption

Hint 22

Adsorption is like stuff sticking to fly paper. Carbon has a large surface area allowing odor compounds to get externally trapped (adsorbed).

Front 23

What is a typical detention time for a primary clarifier?

Back 23

1 to 2 hours

Hint 23

1 to 2 hours is the standard detention time of a primary clarifier.

A typical secondary clarifier detention time is about 2 to 4 hours.

Front 24

What percent of the settleable solids are typically removed through primary clarification?

Back 24

100%

Hint 24

The standard definition of a settleable solid are those solids that settle within 60 minutes.

Typical primary clarification provides more than 1 hour of detention time ... hence, all settleable solids will settle in the primary clarifier.

Front 25

Which is true?

Back 25

Activated carbon is very non-selective in the removal of odor contaminants

Hint 25

Non-selective means that it will remove a wide array of odor compounds. The trade-off is that carbon can become "spent" very quickly because it removes various odor species.

Front 26

What is the basic purpose for the grit removal system?

Back 26

To protect downstream equipment, pipe elbows, valve seats, pump impellers, and other components from wear and erosion.

Hint 26

Protection of equipment components is always a good investment.

Front 27

What does H2S smell like at low concentrations?

Back 27

Rotten eggs

Hint 27

It's easy to initially smell low concentrations of H2S ... it smells real bad! Rotten eggs is an awful odor ... try it, you'll hate it!

Front 28

Associated with primary clarifier scum, what does FOG mean?

Back 28

Fat, Oil, Grease

Front 29

Which chemical is typically used to regenerate the carbon bed of an activated carbon odor control system?

Back 29

Sodium hydroxide

Hint 29

The addition of caustic to a bed of activated carbon, elevating the pH to about 12, acts to desorb H2S from the media.

Front 30

The main purpose of primary treatment is to remove:

Back 30

TSS & CBOD5

Hint 30

Typical primary treatment removes less of the influent CBOD5 as compared to the removal rate of the influent TSS.