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30 Cards in this Set
- Front
- Back
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What does H2S smell like at low concentrations?
? Rotten eggs ? Anaerobic sludge ? Sulfuric acid ? No smell |
Correct!
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! |
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Which chemical is typically used to regenerate the carbon bed of an activated carbon odor control system?
? Alum ? Acid ? Sodium hydroxide ? Methanol |
The addition of caustic to a bed of activated carbon, elevating the pH to about 12, acts to desorb H2S from the media.
Your score is 50%. |
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What does H2S smell like at high concentrations?
? Rotten eggs ? Anaerobic sludge ? Sulfuric acid ? No smell |
There is no smell because the high concentration of H2S basically deadens the sense of smell (olfactory fatigue).
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What is the guideline velocity number for proper grit removal?
? 1.0 fps ? 1.5 fpm ? 1.0 fpm ? 1.0 rpm |
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.
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Where is a typical location to pump primary sludge?
? Aerobic Digestion ? Secondary Clarifier ? Anaerobic Digestion ? Gravity Belt Thickener |
Most plants with primary clarifiers also have anaerobic digestion to accomplish stabilization of the primary sludge.
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What does H2S turn into that causes the damage to concrete and metal?
? Hydrogen peroxide ? Hydrogen sulfide ? Sulfuric acid ? Hydrogen sulfate |
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 |
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Which is true?
? Activated carbon is very selective in the removal of odor contaminants ? Activated carbon is very non-selective in the removal of odor contaminants |
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
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What is a typical detention time for a primary clarifier?
? 4 to 8 Hours ? 1 to 2 Hours ? 30 to 45 Minutes ? 15 Minutes at Peak Flow |
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 |
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Which chemical is typically used for wet scrubber odor control at the solids handling portion of a plant?
? Acid ? Polymer ? Caustic soda ? Sodium hydroxide |
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).
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Which chemical is typically used for wet scrubber odor control at the headworks of a plant?
? Acid ? Polymer ? Sulfur dioxide ? Sodium hydroxide |
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
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What is the basic purpose for the grit removal system?
? To protect the valuable capacity of tanks and process units (by not filling them with grit). ? To protect downstream equipment, pipe elbows, valve seats, pump impellers, and other components.from wear and erosion. ? To improve chlorination ? To improve sludge dewatering |
Protection of equipment components is always a good investment. Also see A
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Associated with primary clarifier scum, what does FOG mean?
? Fully Organic Gold ? Far Oily Gate ? Fat Oil Grease ? Fat Old Guy |
It just does!
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What is the basic purpose for the screenings removal process?
? To stop bacteria growth ? To protect downstream pipes, pumps, valves, and other components from plugging. ? For sample testing ? To remove inorganic material |
Screenings removal is essential to maintain maximum operational capacity of pumps and pipes.
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A screenings removal unit with less than ½ inch openings is known as:
? A coarse bar rack ? A manual bar screen ? A fine bar/filter screen ? A comminutor |
These units are typically automated and controlled by timers or differential head across the screen
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The main purpose of primary treatment is to remove:
? Chlorine ? TSS & CBOD5 ? Ammonia ? Inorganic material |
Typical primary treatment removes less of the influent CBOD5 as compared to the removal rate of the influent TSS.
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Which principle does the wet scrubber use for odor control?
? Absorption ? Adsorption ? Desorption ? Sequestering |
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
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Aerated grit chambers usually utilize what type of aeration system?
? Mechanical ? Diffused ? Transverse ? Low speed mixer |
The diffusers are typically located along one side of the tank creating a rolling action across the tank's width.
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Which principle does the activated carbon system use for odor control?
? Absorption ? Adsorption ? Desorption ? Sequestering |
Adsorption is like stuff sticking to fly paper. Carbon has a large surface area allowing odor compounds to get externally trapped (adsorbed).
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What is H2S?
? Hydrogen peroxide ? Hydrogen sulfide ? Sulfuric acid ? Hydrogen sulfate |
Hydrogen peroxide is H2O2. Sulfuric acid is H2SO4
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What percent of the settleable solids are typically removed through primary clarification?
? 20 to 30% ? 40 to 60% ? 25 to 30% ? 100% |
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 |
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What does SOR mean (associated with primary clarification)?
? Standard Operating Regime ? Sand Organic Rut ? Surface Operating Rotation ? Surface Overflow Rate |
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)
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Grit is mainly:
? Inorganic material ? Organic material ? Total suspended solids ? Volatile solids |
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.
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What does this formula represent?
(IN - OUT) ÷ IN x 100 = % ? SOR ? Detention Time ? Removal Efficiency ? Loading Rate |
This formula will calculate removal efficiency of most constituents ... TSS, CBOD5, TN, TP, etc.
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What method of grit removal is the Pista Grit system?
? Free vortex ? Low velocity ? High velocity ? Forced vortex |
Forced vortex means that is 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
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What adjustment is generally necessary when gas and/or solids rise to the surface of a primary clarifier?
? Increase the amount of primary sludge withdrawal ? Decrease the amount of primary sludge withdrawal ? Stop pumping primary sludge ? Gas and rising sludge is normal ... not a problem |
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 |
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Screenings debris is mainly:
? Inorganic material ? Organic material ? Total suspended solids ? Egg shells |
Most material captured and removed by a bar screen is organic ... volatile.
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Is H2S lighter or heavier than air?
? lighter ? heavier |
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
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What device is more commonly used for separation of grit slurry?
? Aerated grit chamber ? Clarifier ? Cyclone classifier ? Air lift |
These devices basically spin the grit out of the slurry using centrifugal force
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What is a typical range for an SOR within a primary clarifier?
? 1 to 2 Hours ? 100 to 200 gpd/ft ? 400 to 550 degrees C ? 800 to 1,000 gpd/ft2 |
Hydraulic loading rates are typically higher in primary clarifiers than secondary clarifiers.
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Typical primary clarification removes TSS in which range?
? 20 to 30% ? 40 to 60% ? 25 to 30% ? 100% |
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 |
