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Class C Wastewater Treatment Plant Operator Questions

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Wastewater Wastewater Treatment Study Material Quiz on Class C Wastewater Treatment Plant Operator Questions, created by Dean Lampman on 29/12/2017.
Dean Lampman
Quiz by Dean Lampman, updated more than 1 year ago
Dean Lampman
Created by Dean Lampman over 6 years ago
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Resource summary

Question 1

Question
pH is the measure of
Answer
  • Amount of an acid
  • Intensity of basic or acidic condition of a liquid
  • Acidity
  • Alkalinity

Question 2

Question
The second stage of anaerobic digestion is called
Answer
  • Acid formation
  • Stabilization
  • Methane formation
  • Pathogenic formation

Question 3

Question
One liter of elemental liquid chlorine can evaporate and produce how many liters of chlorine gas
Answer
  • 100
  • 250
  • 457
  • 567

Question 4

Question
Chlorine gas is how many times heavier than air?
Answer
  • 1 times
  • 2.5 times
  • 7 times
  • 25 times

Question 5

Question
PLANT PROBLEM: Plant effluent coliform count fails to meet required standards for disinfection. Chlorine residual is normal. Disinfection supplies are not a problem.
Answer
  • Capacity of chlorinator too low
  • Too little solids in effluent
  • Contact time too short
  • Chlorine demand too high

Question 6

Question
The most important adjustments to the activated sludge process are made by adjusting
Answer
  • Aeration, pH, and RAS
  • Aeration, pH and WAS
  • RAS, WAS and aeration
  • pH, RAS and WAS

Question 7

Question
Problem: Classic sludge bulking occurring in the final clarifier of a conventional activated sludge plant. Indicators include solids pouring over the weirs, excessive floc observed at the surface, and a homogenous sludge blanket appearing throughout the clarifier. Sludge in settling test settles slowly leaving a cloudy supernatant. What is the MOST probable cause?
Answer
  • Over-oxidized sludge
  • Hydraulic washout
  • Young sludge
  • SVI too low

Question 8

Question
PROBLEM: Operational data is given below for a primary clarifier: Influent flow: 2.5 mgd Primary tank volume: 41,310 cubic feet
Answer
  • 0.3 hours
  • 3.0 hours
  • 13.0 hours
  • 16.8 hours

Question 9

Question
As the operator of a primary clarifier, you notice black and odorous septic wastewater leaving the clarifier. What is the probable cause?
Answer
  • Withdrawing sludge too frequently
  • Improper sludge removal
  • Excessive I&I entering WWTP
  • Excessive oil and grease entering WWTP

Question 10

Question
PROBLEM: Plant fecal coliform counts do not meet State standards. The chlorine supply is not the problem, there is adequate vacuum and chlorine feed. The chlorine contact tank has no solids build-up and the effluent flow is below design. That is the MOST likely cause?
Answer
  • High chlorine demand from excessive ammonia in effluent
  • High chlorine demand from excessive nitrate in effluent
  • High chlorine demand from excessive nitrite in effluent
  • High chlorine demand from excessive polymer in effluent

Question 11

Question
A fixed sample is
Answer
  • Not broken
  • A sample purposely 'spiked' by the lab technician for QA/QC
  • A series of composite samples
  • A sample preserved in the field upon completion

Question 12

Question
According to FDEP Chapter 62-602 FAC, an operator could have his/her license permanently revoked for
Answer
  • Falsified or misrepresented reports, logs or lab sheets
  • Cheating on an exam
  • Incompetence in operation of a wastewater treatment plant
  • Submitting false data on license application

Question 13

Question
PROBLEM: Excessive white, billowing foam in the aeration tank surface.
Answer
  • pH too high
  • MLSS too low
  • Waste temperature too high
  • WAS too low

Question 14

Question
According to Chapter 62-620 FAC, Wastewater Permitting, plant records must be maintained on-site for how many years?
Answer
  • One year
  • Three years
  • Five years
  • Forever

Question 15

Question
What happens in the stabilization (re-aeration) tank in the contact-stabilization process?
Answer
  • Adsoption of the activated floc
  • Adsorption of waste material by microorganisms
  • Agglomeration of the activated floc
  • Adsorption and digestion of the waste material collected by microorganisms

Question 16

Question
PROBLEM: Good settling in the 30 minute settleability test. Excessive floc billowing in the clarifier and washing out. Sludge scrapers and RAS system appear normal. What is the BEST solution to fix the problem?
Answer
  • Lower aeration tank effluent weirs
  • Increase RAS
  • Add chlorine to RAS
  • Reduce clarifier hydraulic loading rates.

Question 17

Question
PROBLEM: Classic sludge bulking occurring in the final clarifier of a conventional activated sludge plant. Indicators include solids pouring over the weirs, excessive floc observed at the surface, and a homogenous sludge blanket appearing throughout the clarifier. Sludge in settling test settles slowly leaving a cloudy supernatant. What is the necessary check to confirm the cause?
Answer
  • Weir over flow rate
  • Determine effluent suspended solids concentration
  • Calculate the sludge age
  • DO in the aeration tank

Question 18

Question
In a well operated activated sludge plant, when the RAS rate is decreased but the WAS rate remains constant, the expected conditions would be
Answer
  • MLSS decreases, F/M Ration increases, MCRT decreases
  • MLSS decreases, F/M Ration decreases, MCRT increases
  • MLSS increases, F/M Ration increases, MCRT decreases
  • MLSS increases, F/M Ration decreases, MCRT increases

Question 19

Question
The first step in anaerobic digestion is called
Answer
  • Acid formation
  • Stabilization
  • Methane formation
  • Alkalinity formation

Question 20

Question
A screenings dumpster is full at the headworks of the treatment plant. The dumpster is 6 ft tall, 10 ft long and 8 ft wide. How many cubic yards of screenings myst be disposed of.
Answer
  • 17.8
  • 129.6
  • 480.0
  • 575.0

Question 21

Question
The two main gases formed in the anaerobic digestion process are
Answer
  • Nitrogen and oxygen
  • Methane and oxygen
  • Methane and water
  • Methane and carbon dioxide

Question 22

Question
In an activated sludge plant, if the DO in the aeration tank suddenly decreases and the aerators are not the problem, what is the most probable cause
Answer
  • F/M Ratio decreased
  • Increased organic load into tank
  • Denitrification occuring
  • MCRT too long

Question 23

Question
How many fusible plugs can be found on a one-ton chlorine container?
Answer
  • 1
  • 2
  • 6
  • There are no fusible plugs on a one-ton container

Question 24

Question
A fire has started in the maintenance shop due to an ignition of petroleum oil. Which type of fire extinguisher should not be used to fight the fire?
Answer
  • CO2
  • Purple K
  • Pressurized water
  • Dry chemical

Question 25

Question
Mixing dry granular chlorine with petroleum products will
Answer
  • Create anhydrous chlorine dioxide
  • Create an explosive device
  • Create hydrogen dioxide
  • Create a white cloud

Question 26

Question
A confined space is defined as having a space large enough to bodily enter and perform work, has limited entry and egress and is _______________ ?
Answer
  • Not designed for continuous occupancy
  • Designed for state exam prep classes
  • Not designed to perform strenuous computer calculations
  • Designed as a long term hurricane and tornado shelter

Question 27

Question
What is the dosage of chlorine, in mg/L, if the flow being treated is 85,000 gpd and 3 pounds of chlorine are used per day?
Answer
  • 0.42 mg/L
  • 1.4 mg/L
  • 2.3 mg/L
  • 4.2 mg/L

Question 28

Question
When properly adjusted, the rope packing on a centrifugal pump is designed to leak how much?
Answer
  • One drip per second
  • One drip per hour
  • A steady, pencil sized stream should flow at all times
  • There should be NO leaks from a rope packing

Question 29

Question
In a lab, a dilute acid solution must be prepared for titration in the alkalinity test. The proper procedure for making the weak acid is to:
Answer
  • Add the water slowly to the concentrated acid to begin dilution
  • Add the water quickly to the acid to begin dilution
  • Add the acid directly to the sample without dilution
  • Add the acid slowly to the dilution water

Question 30

Question
What is the removal efficiency of the solids contact/trickling filter process if the influent TSS is 439 mg/L and the plant effluent TSS is 4.0 mg/L?
Answer
  • 4%
  • 40%
  • 89%
  • 99%

Question 31

Question
As an operator of a gravity thickener, you notice floating sludge rising throughout the thickener. All of the following may be a cause for the problem EXCEPT
Answer
  • Sludge decomposing in the tank
  • Sludge collection mechanism is off
  • Insufficient sludge removal
  • Sludge blanket too low

Question 32

Question
PROBLEM: Upon arriving at the package treatment plant serving a small community, you find a uniform sludge blanket rising throughout the clarifier. A settlettling sludge leaving a clear supernatant. MLSS test results are normal, but a calculation of the SVI shows a high sludge volume indability test reveals a very slow seex. What is the MOST likely cause of the high sludge blanket ?
Answer
  • The operator has wasted too much sludge, causing a young sludge condition
  • An extreme rain event washed out the majority of the solids
  • Filamentous bacteria are causing the slow settling
  • An overdose of chlorine has killed the floc forming and filament bacteria

Question 33

Question
PROBLEM: Solids are washing out of the secondary clarifier of the activated sludge plant. Plant personnel increase the return activated sludge (RAS) flow rate, which slows the problem temporarily, but gets worse after 30 minutes. What is the cause of the plant problem?
Answer
  • Increasing the RAS increased the detention time in the clarifier
  • Increasing the RAS decreased the detention time in the clarifier
  • Increasing the RAS increased the detention time in the aeration tank
  • Increasing the RAS caused the DO in the aeration tank to increase

Question 34

Question
PROBLEM: Solids are washing out of the secondary clarifier of the activated sludge plant. A settleability test shows good settling CAN occur. The MOST likely cause of the problem is:
Answer
  • High flows are entering the treatment plant
  • The RAS rate is too low
  • Denitrification is occurring in the chlorine contact tank
  • The sludge collector mechanism is rotating clockwise

Question 35

Question
PROBLEM: The chlorine residual is falling, and inspection of the 150 lb cylinder and chlorine feed equipment shows ice forming on the chlorine regulator and feed lines. The BEST method to fix the falling chlorine residual is:
Answer
  • switch over to sodium hypochlorite solution
  • place a second chlorine cylinder on-line
  • roll the cylinder so liquid is feeding instead of gas
  • place a 1500W space heater next to the cylinder to thaw the ice

Question 36

Question
The fusible plug on a chlorine cylinder is designed to:
Answer
  • Melt at 1500 degrees F
  • Prevent a dangerous vacuum from forming in the cylinder
  • Melt at 158-165 degrees F
  • Melt when placed in the direct sunlight

Question 37

Question
How many times heavier than air is methane gas?
Answer
  • 1 time
  • 2.5 times
  • 4.6 times
  • Methane is lighter than air

Question 38

Question
The combination of methane and _____________ can be very combustible?
Answer
  • Carbon monoxide
  • Carbon dioxide
  • Carbon tetrazini
  • Oxygen

Question 39

Question
A class C fire extinguisher is safe to use of what type of fire?
Answer
  • Ordinary paper, wood and trash
  • Flammable fuels
  • Electrical equipment
  • Flammable metals

Question 40

Question
F/M Ratio can be BEST be described as:
Answer
  • The pounds of CBOD applied to a pound of MLVSS
  • The amount of influent TSS applied to the aeration tank
  • The loading of solids to a trickling filter
  • The amount of soluble CBOD fed to an RBC

Question 41

Question
According to FDEP chapter 62-601, FAC, a composite sample shall be used for which test?
Answer
  • Total chlorine residual
  • Effluent CBOD
  • Effluent pH
  • Effluent fecal coliform

Question 42

Question
According to FDEP chapter 62-604.550 (a) FAC, a wastewater spill shall be verbally reported to the state warning point no later than:
Answer
  • 8 hours from discovery
  • 12 hours from discovery
  • 24 hours from discovery
  • 72 hours from discovery

Question 43

Question
According to F DEP chapter 62-600.440 (4)(b), basic disinfection is described as:
Answer
  • A chlorine residual of 0.5 mg/L for 30 minutes at peak hourly flow
  • A chlorine residual of 1.0 mg/L for 15 minutes at peak hourly flow
  • A chlorine residual of 0.5 mg/L for 15 minutes at peak hourly flow
  • A chlorine residual of 0.5 mg/L for 30 minutes at average daily flow

Question 44

Question
According to FDEP chapter 62-600.440 (4)(c) 4, basic level disinfection, any ONE sample may not exceed how many colonies per 100 ml sample?
Answer
  • 100
  • 200
  • 500
  • 800

Question 45

Question
The preservative used for transport of the fecal coliform sample is:
Answer
  • Ice the sample for no less than 6 hours minimum
  • Ice to 4 degrees C
  • 0.5% nitric acid
  • 0.2% sulfuric acid
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