Drinking Water Treatment Practice Exam (OHIO Class 1)
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Questions and Answers

Many sources of water are directly suitable for drinking purposes without treatment.

False

Water treatment plant operators have the responsibility for the health and well-being of the community they serve.

True

What is the purpose of coagulation-flocculation?

  • To filter out suspended particles
  • To settle out larger suspended particles
  • To control corrosion
  • To gather together fine, light particles to form floc to aid the sedimentation and filtration processes. (correct)

    • What is the purpose of filtration?

    <p>To filter out suspended particles</p> Signup and view all the answers

    What is the main purpose of a water treatment plant's intake structure?

    <p>To draw in water while preventing leaves and other debris from clogging or damaging pumps</p> Signup and view all the answers

    Smaller sized particles, such as bacteria and fine clays and silts, readily settle out of water.

    <p>False</p> Signup and view all the answers

    Overdosing as well as underdosing of coagulants may lead to reduced solids removal efficiency.

    <p>True</p> Signup and view all the answers

    The maximum allowable level of turbidity in water is 0.5 NTU with a recommended level of 0.1 NTU.

    <p>True</p> Signup and view all the answers

    What is alkalinity?

    <p>The capacity of water to neutralize acids.</p> Signup and view all the answers

    What is the usual culprit when there are sudden increases in filtered water turbidity?

    <p>Poor coagulation-flocculation process performance</p> Signup and view all the answers

    The settling rate of a particle becomes much slower as the temperature increases.

    <p>False</p> Signup and view all the answers

    Whenever actual flows in a water treatment plant approach or exceed design flows, problems are likely to develop.

    <p>True</p> Signup and view all the answers

    What are the purposes of the sedimentation process?

    <p>To remove suspended solids that are denser than water and to reduce the load on the filters</p> Signup and view all the answers

    What is adsorption?

    <p>The taking in or soaking up of one substance into the body of another by molecular or chemical action</p> Signup and view all the answers

    What is filter backwashing?

    <p>A process of reversing the flow of the water through the filter media to remove the entrapped solids.</p> Signup and view all the answers

    Direct filtration is considered a feasible alternative to conventional filtration when source waters are low in which constituent?

    <p>Turbidity</p> Signup and view all the answers

    Excessive turbidity will greatly increase the efficiency of the disinfecting chemical process.

    <p>False</p> Signup and view all the answers

    Organics found in the water can consume great amounts of disinfectants while forming unwanted compounds.

    <p>True</p> Signup and view all the answers

    The demand for chlorine must be satisfied before chlorine becomes available to accomplish disinfection.

    <p>True</p> Signup and view all the answers

    Which of the following is direct filtration?

    <p>Coagulation &gt; Flocculation &gt; Filtration</p> Signup and view all the answers

    The minimum number of filter modules is __________.

    <p>2</p> Signup and view all the answers

    Multi-media filters use sand, anthracite coal, and ________ for the filter media.

    <p>Garnet</p> Signup and view all the answers

    Which of the following processes takes the longest amount of time?

    <p>Flocculation</p> Signup and view all the answers

    Detention time is theoretical time required ___________.

    <p>For the water to pass through a basin at a given rate of flow</p> Signup and view all the answers

    Which of the following factors affects the settling of floc in the sedimentation basin?

    <p>The length of the backwash cycle</p> Signup and view all the answers

    What happens if the velocity of water leaving the sedimentation basin is too high?

    <p>Floc may be carried over to the filters</p> Signup and view all the answers

    The purpose of the sludge zone is to ______________.

    <p>Allow the floc to settle</p> Signup and view all the answers

    The chemical name for bleach is ____________.

    <p>Hypochlorite</p> Signup and view all the answers

    Which form of chlorine has the highest disinfecting ability in water?

    <p>Chlorine gas</p> Signup and view all the answers

    Which of the following water quality parameters is of greatest concern with UV disinfection?

    <p>Turbidity</p> Signup and view all the answers

    What is the effect of organics in water on disinfection?

    <p>May form THMs</p> Signup and view all the answers

    The 1986 amendments to the Safe Drinking Water Act required the U.S.EPA to ____________.

    <p>Define approved treatment techniques for regulated contaminants</p> Signup and view all the answers

    The maximum allowable level of turbidity in water is

    <p>0.5 NTU</p> Signup and view all the answers

    Put the steps of coagulation and flocculation in order from first to last:

    <p>Chemical dosing, flash mix, gentle mix</p> Signup and view all the answers

    The ideal size for floc is between

    <p>0.1 and 3 mm</p> Signup and view all the answers

    Poor floc formation could be the result of

    <p>Insufficient mixing</p> Signup and view all the answers

    Secondary coagulants aid primary coagulants by adjusting the pH and providing additional surface area.

    <p>True</p> Signup and view all the answers

    To determine which chemicals are the most effective and the proper dose to achieve the desired results, you should conduct a(n) ____________.

    <p>Jar test</p> Signup and view all the answers

    The frequency and amount of sludge removed from the sedimentation basin depends on.

    <p>Floc settling in the basin</p> Signup and view all the answers

    Sedimentation works by increasing the velocity of the water so suspended particles settle.

    <p>False</p> Signup and view all the answers

    In the inlet zone, the velocity of water is _____________ to keep the floc from breaking.

    <p>Slowed</p> Signup and view all the answers

    Which agency regulates bottled water?

    <p>FDA</p> Signup and view all the answers

    If a treatment plant violates a secondary standard, they may face enforcement action.

    <p>False</p> Signup and view all the answers

    The standard requires the removal for Giardia and viruses at

    <p>99.9%</p> Signup and view all the answers

    The most severe violation is a health hazard, which is classified as ________.

    <p>Tier 4</p> Signup and view all the answers

    The minimum contact time for chlorine is

    <p>30 minutes</p> Signup and view all the answers

    A system is classified as a Public Water System if it serves more than 25 individuals daily at least 60 days of the year or has more than 15 connections.

    <p>True</p> Signup and view all the answers

    Transient Noncommunity Water Systems serve at least 25 of the same people over 6 months.

    <p>True</p> Signup and view all the answers

    Study Notes

    Water Treatment Basics

    • Many water sources require treatment before being deemed suitable for drinking.
    • Water treatment operators play a critical role in ensuring community health and safety.

    Coagulation and Filtration Processes

    • Coagulation-flocculation aims to cluster fine particles into floc for easier removal.
    • Filtration is essential to eliminate suspended particles from water.

    Water Intake Structures

    • The intake structure of a water treatment plant is designed to draw in water while filtering out debris that could damage the pumps.

    Turbidity Standards

    • The maximum allowable turbidity in drinking water is 0.5 NTU, with 0.1 NTU being the recommended level.
    • Excessive turbidity can hinder the effectiveness of disinfection processes.

    Chemical Properties and Treatment

    • Alkalinity is the water's capacity to neutralize acids, which is crucial for maintaining pH levels during treatment.
    • Organics in water can react with disinfectants, creating unwanted byproducts, such as trihalomethanes (THMs).

    Processes in Water Treatment

    • Coagulation involves introducing coagulants to clump particles, followed by flocculation and then sedimentation to remove these larger aggregates.
    • Backwashing filters is a necessary step to clean the filter media by reversing water flow to dislodge trapped particles.

    Water Quality Management

    • Chlorine gas possesses the highest disinfecting ability compared to other forms of chlorine.
    • Turbidity significantly impacts the efficacy of UV disinfection, which is sensitive to the clarity of water.

    Regulatory Framework

    • The 1986 amendments to the Safe Drinking Water Act mandated the U.S. EPA to outline treatment techniques for regulated contaminants.
    • A public water system must serve over 25 people daily or have more than 15 connections to meet classification criteria.

    Hazard Classification and Treatment Requirements

    • The most serious violations of health standards are classified as Tier 4 hazards.
    • The minimum contact time for chlorine to ensure effective disinfection is set at 30 minutes.

    Practical Application in Treatment Plants

    • Direct filtration is viable when source waters have low turbidity levels, while insufficient mixing can lead to poor floc formation.
    • Understanding sedimentation dynamics is essential as high water velocities can lead to floc carryover into filters.

    Testing and Monitoring

    • Conducting a jar test is critical for identifying effective coagulants and determining appropriate dosing.
    • The frequency of sludge removal from sedimentation tanks depends on floc settling efficiency.

    Definitions and Terminology

    • Adsorption refers to the process where substances cling to the surface of materials, an important concept in water treatment chemistry.
    • Transient Noncommunity Water Systems serve groups of individuals but do not maintain the same population for extended periods.

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    Description

    Test your knowledge on drinking water treatment with this practice exam designed for OHIO Class 1. The quiz includes questions on the responsibilities of water treatment plant operators and the processes involved in water purification. Ideal for those preparing for certification or seeking to enhance their understanding of water safety.

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