Water Treatment Class D Practice Exam - Prof. Authur, Exams of Water and Wastewater Engineering

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#3) Q&A’s 100% Verified Correct

What is the criteria for a community water system? - ANS ✔ - Has at least 15 service connections used by all year residents, or regularly serves at least 25 all year residents

What is the acceptable limit of copper in drinking water? - ANS ✔ - 1.3 mg/L

Which type of reservoir is rich in nutrients? - ANS ✔ - eutrophic

What is a mechanical seal? - ANS ✔ - Metallic flat surfaces used to minimize leakage around the pump shaft.

What is a confined aquifer? - ANS ✔ - An aquifer that is bounded above and below by confining beds

Which of the following best describes pumping water level in a well? - ANS ✔ - Upper surface of the groundwater that is being pumped

What is the name of the deepest layer of a reservoir under thermal stratification? - ANS ✔ - hypolimnion

What is the health effect of consuming water with high levels of copper? - ANS ✔ - Stomach and intestinal distress such as nausea, vomiting, diarrhea and stomach cramps

Which of the following best describes a turbine pump? - ANS ✔ - A centrifugal pump that is mainly used to pump water from wells

What is typically used to clean the sludge on the bottom of a rectangular clarifier? - ANS ✔ - Chain and flight collectors

#3) Q&A’s 100% Verified Correct

How often should preventative maintenance be performed on equipment? - ANS ✔ - Use manufacturer's recommendation.

What is CT? - ANS ✔ - Contact time x chlorine residual concentration

What is absorption? - ANS ✔ - Constituent is sucked in

What is the purpose of a check valve? - ANS ✔ - Allows water to flow in one direction, and prevents reverse flow

What would happen to the pH of water if lime is added? - ANS ✔ - increases pH

What is the term used to describe groundwater that flows naturally from the ground? - ANS ✔ - spring

Once thermal stratification occurs in the middle and lower zones of a reservoir, what type of problem occurs in these layers? - ANS ✔ - Depletion of total dissolved oxygen

What is the most critical problem that may be encountered when entering a confined space? - ANS ✔

• Oxygen deficiency and toxic gas

Which of the following is a settle able solid? - ANS ✔ - Sand

Which of the following is not a commonly used coagulant? - ANS ✔ - sodium hypochlorite

What is the purpose of a coagulant aid? - ANS ✔ - Add density to slow-settling flocs and add toughness to the flocs.

What is the purpose of coagulant (not coagulant aid)? - ANS ✔ - Neutralize electrical charge.

#3) Q&A’s 100% Verified Correct

Which of the following is least likely to be removed in the sedimentation process? - ANS ✔ - Aqueous form of manganese

In the sedimentation process, what would happen if the flowrate were increased? - ANS ✔ - lower efficiency

If turbidity is rising rapidly, what should you do? - ANS ✔ - Verify the effectiveness of the coagulant chemicals and dosage at the flash mixer

The collection of a bad sample is useful as which of the following? - ANS ✔ - No result

Which of the following is not a mechanism that occurs in a filter media? - ANS ✔ - precipitation

Which of the following is not a type of filter media used for gravity filtration? - ANS ✔ - diatomaceous earth

What are the three types of media used in a multimedia filtration system? - ANS ✔ - sand, anthracite coal, garnet

What does the term "fluidized" mean in filtration? - ANS ✔ - Filter media is expanded during backwash

Which of the following is not an attribute of activated carbon? - ANS ✔ - removes nitrate

How is the filtration efficiency evaluated? - ANS ✔ - turbidity measurement

Which of the following is not a way to address backwashing problems in a filter? - ANS ✔ - Adjust chemical injection rate

#3) Q&A’s 100% Verified Correct

Which of the following is a requirement of the surface water treatment rule? - ANS ✔ - At least 99. percent removal of giardia cysts

Which of the following is not a process that will remove pathogens from water? - ANS ✔ - screening

Which of the following will be formed when free chlorine combines with water? - ANS ✔ - hypochlorous acid

Which of the following is true about chlorine gas, by itself? - ANS ✔ - Nonflammable and nonexplosive.

What is the most common source of waterborne disease outbreaks? - ANS ✔ - backflow

Why would a water utility switch from using sodium hypochlorite to chloramines? - ANS ✔ - Reduce formation of THMs

What is a CT value? - ANS ✔ - A measure of the degree of pathogenic inactivation.

When is a hypo chlorinator typically used? - ANS ✔ - To feed liquid chlorine.

Which contaminant should never be sampled using a composite sample? - ANS ✔ - bacteria

If liquid chlorine is leaking from a cylinder, what you should do - ANS ✔ - Turn the Container so that the leak is on top

Which of the following provides the most convenient and repeatable chlorine residual results? - ANS ✔ - Amperometric titration

Which of the following does not have a primary MCL? - ANS ✔ - Iron

#3) Q&A’s 100% Verified Correct

Which of the following is not true about chlorine gas? - ANS ✔ - Most people cannot detect chlorine gas at about 2 ppm.

What is the disadvantage of using ozone to disinfect water? - ANS ✔ - Cost

What is the most common technique used to control taste and odor? - ANS ✔ - PAC

What does an organic compound always contain? - ANS ✔ - Carbon

Which of the following is a type of acid? - ANS ✔ - hydrochloric

Select the answer that violates the basic rules or laboratory work - ANS ✔ - Pipet hazardous materials with your mouth

Which of the following is true regarding water sampling? - ANS ✔ - Collecting water samples at a water treatment plant is no different than collecting samples from a stream or river.

What has a "rotten egg" smell? - ANS ✔ - hydrogen sulfide

Which coliform bacteria test involves the use of lauryl tryptose broth? - ANS ✔ - Multiple tube fermentation method

How alkalinity is usually expressed? - ANS ✔ - Calcium carbonate equivalents

What does a pH of 2 represent? - ANS ✔ - Strong acid

What impact does total dissolved solids (TDS) have on water quality? - ANS ✔ - adverse taste

#3) Q&A’s 100% Verified Correct

What is the optimum pH of water for disinfecting bacteria? - ANS ✔ - 7.

What is wire-to-water efficiency? - ANS ✔ - The combine efficiency of a pump and motor.

Select the answer that is not a type of positive displacement pump - ANS ✔ - Metering

Which of the following rotates at a high speed and imparts velocity to the water? - ANS ✔ - Impeller

What is the term used to describe a connection between a drinking water system and an unapproved water supply? - ANS ✔ - cross connection

Which is the term used to describe the shallow water of a reservoir with abundant plant growth? - ANS ✔ - littoral zone

What impacts do algal blooms have on the pH of a reservoir? - ANS ✔ - Increases pH

What type of charge would you expect to see on a coagulant? - ANS ✔ - positive

What would cause excessive media to be in the spent backwash water? - ANS ✔ - Backwashing at high velocity

What safety equipment must be worn before entering a confined space? - ANS ✔ - harness

What are the typical characteristics of the source water for a direct filtration plant? - ANS ✔ - Low turbidity level, less than 2 NTU.

What is the purpose of the coagulation and flocculation process? - ANS ✔ - Neutralize the negative charges on the colloids, and slowly stir water to create flocs.

#3) Q&A’s 100% Verified Correct

Which of the following would not trigger a filtration system to backwash? - ANS ✔ - temperature

What is the definition of disinfection? - ANS ✔ - Inactivation of most pathogens

Which if of the following is secondary contaminant? - ANS ✔ - Manganese

What is the safety hazard of working with polymers? - ANS ✔ - Slippery floor

What is the disadvantage of using chloramines? - ANS ✔ - Weak disinfectant.

What is the purpose of a dial indicator? - ANS ✔ - measure shaft misalignment

What is an attribute of a diatomaceous earth filter? - ANS ✔ - Mesh screen is pre-coated with powdered media.

Which of the following is true about the presumptive test? - ANS ✔ - It takes 48hours to obtain results for the total coliform test

What is a carcinogen? - ANS ✔ - causes cancer

What is the minimum required disinfection residual concentration leaving a surface water treatment plant? - ANS ✔ - 0.2 mg/L

Which of the following is equal to 1ppm - ANS ✔ - 1mg/L

What is the disadvantage of using UV to disinfect water? - ANS ✔ - No disinfectant residual

#3) Q&A’s 100% Verified Correct

What would most likely occur if a higher quantity of chlorine is added to water? - ANS ✔ - More THMs will form.

What is the most common error in water quality analysis? - ANS ✔ - Sampling

What is the term used to describe the introduction into water of microorganisms, chemicals, and toxic substances in a concentration that makes the water unfit for its next intended use? - ANS ✔ - contamination

Which acid is formed when chlorine is mixed with water? - ANS ✔ - hypochlorous acid