Water Treatment Plant Operator Volume 2 Chapter 12

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  • 1/26 Questions

    One way to rid a distribution system of iron bacteria is to develop a flushing program.

    • True
    • False
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About This Quiz

This quiz assesses knowledge on water treatment processes focusing on iron and manganese removal. It covers topics like health effects, treatment methods, and chemical oxidation, essential for operators in training.

Chapter 12 Quizzes & Trivia

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  • 2. 

    If the water to be treated contains no oxygen, both iron and manganese may be removed by ion exchange using the same resins that are used for water softening.

    • True

    • False

    Correct Answer
    A. True
    Explanation
    If the water to be treated contains no oxygen, both iron and manganese may be removed by ion exchange using the same resins that are used for water softening. This is because ion exchange resins are capable of removing both iron and manganese ions from water. The absence of oxygen does not affect the ability of ion exchange resins to remove these contaminants. Therefore, it is true that both iron and manganese can be removed using the same resins used for water softening.

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  • 3. 

    Chlorine will oxidize manganese to the insoluble manganese dioxide and will oxidize iron to insoluble ferric hydroxide.

    • True

    • False

    Correct Answer
    A. True
    Explanation
    Chlorine is a strong oxidizing agent, meaning it can cause the oxidation of other substances. In this case, it will oxidize manganese to form insoluble manganese dioxide, and it will also oxidize iron to form insoluble ferric hydroxide. Therefore, the statement is true.

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  • 4. 

    Chlorine should never be fed ahead of polyphosphate to oxidize iron and manganese.

    • True

    • False

    Correct Answer
    A. True
    Explanation
    Chlorine should never be fed ahead of polyphosphate to oxidize iron and manganese because chlorine can react with polyphosphate, causing it to break down and lose its effectiveness in preventing the formation of iron and manganese deposits. By feeding chlorine ahead of polyphosphate, the polyphosphate will not be able to properly coat the iron and manganese particles, leading to potential issues with water quality and the formation of deposits. Therefore, it is important to avoid feeding chlorine ahead of polyphosphate in order to maintain the desired water treatment results.

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  • 5. 

    In some plants the injection for the potassium permanganate solution in the volute of the pump will produce complete mixing of potassium permanganate. 

    • True

    • False

    Correct Answer
    A. True
    Explanation
    The statement suggests that injecting a potassium permanganate solution into the volute of a pump in certain plants will result in complete mixing of the solution. This means that the potassium permanganate will be evenly distributed throughout the pump, ensuring effective treatment or dispersion of the solution. Therefore, the answer "True" indicates that this statement is correct.

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  • 6. 

    One way to avoid the formation of calcium carbonate coatings on poppet valves is to obtain the dilution water for hypochlorite from an ordinary home water softener.

    • True

    • False

    Correct Answer
    A. True
    Explanation
    This statement is true because using water from a home water softener can help prevent the formation of calcium carbonate coatings on poppet valves. Water softeners remove minerals, such as calcium and magnesium, which are responsible for the formation of calcium carbonate deposits. By using softened water, the hypochlorite solution will be free from these minerals and therefore less likely to form coatings on the valves.

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  • 7. 

    Where should samples be collected to analyze for iron and manganese.

    • As close to the well or other source as possible

    • At the entrance to the distribution system

    • At the far end of the distribution system

    • From a sampling tap at the laboratory

    Correct Answer
    A. As close to the well or other source as possible
    Explanation
    Samples should be collected as close to the well or other source as possible in order to accurately analyze for iron and manganese. This is because the concentration of these elements can vary throughout the distribution system, so collecting samples at the source ensures a more representative analysis.

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  • 8. 

    Iron and manganese are least frequently found in water systems supplied by wells and springs.

    • True

    • False

    Correct Answer
    A. False
    Explanation
    Iron and manganese are commonly found in water systems supplied by wells and springs. These elements can dissolve from the surrounding rocks and soil into the groundwater, leading to higher concentrations in well and spring water compared to other water sources. Therefore, the correct answer is False.

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  • 9. 

    Always allow a back siphon condition to develop in a distribution system.

    • True

    • False

    Correct Answer
    A. False
    Explanation
    Allowing a back siphon condition to develop in a distribution system is not recommended. A back siphon occurs when there is a negative pressure in the system, causing water to flow backwards, potentially contaminating the water supply. Backflow prevention devices are installed in distribution systems to prevent back siphonage and protect the water supply from contamination. Therefore, the statement is false, and it is important to prevent back siphon conditions in a distribution system.

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  • 10. 

    What is the most important piece of equipment in an iron and manganese removal plant?

    • Clarifier

    • Comminutor

    • Filter

    • Mixer

    Correct Answer
    A. Filter
    Explanation
    The most important piece of equipment in an iron and manganese removal plant is the filter. This is because the filter is responsible for removing the iron and manganese particles from the water. It works by passing the water through a medium that can trap and remove these contaminants. Without a filter, the iron and manganese would not be effectively removed, resulting in poor water quality. The clarifier is used to separate solids from liquids, the comminutor is used to grind or shred solids, and the mixer is used to mix chemicals or substances. While these pieces of equipment may be important in the overall treatment process, they are not specifically designed to remove iron and manganese.

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  • 11. 

    There are direct adverse health effects from drinking iron or manganese.

    • True

    • False

    Correct Answer
    A. False
    Explanation
    Iron and manganese are essential minerals that our bodies need in small amounts. While excessive intake of these minerals can be harmful, there are no direct adverse health effects from drinking water that contains normal levels of iron or manganese. In fact, both minerals are commonly found in drinking water and are not considered harmful. However, high levels of iron or manganese in water can affect its taste, odor, and appearance, which may be undesirable but not directly harmful to health. Therefore, the correct answer is false.

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  • 12. 

    Why must iron oxidation basins be covered?

    • To keep out disinfection byproduct

    • To keep out rain, stormwater runoff, rodents,and insects

    • To keep out sunlight

    • To prevent evaporation losses.

    Correct Answer
    A. To keep out rain, stormwater runoff, rodents,and insects
    Explanation
    Iron oxidation basins must be covered to prevent contamination from rain, stormwater runoff, rodents, and insects. These external factors can introduce impurities and bacteria into the basin, affecting the oxidation process and the quality of the water being treated. By keeping the basins covered, the risk of contamination is minimized, ensuring that the water remains clean and safe for further treatment or distribution. Additionally, covering the basins also helps to prevent evaporation losses, ensuring that the water levels in the basin remain stable and sufficient for the oxidation process.

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  • 13. 

    How does agitating greensand with an air wash or an air water wash benefit the filter media?

    • Avoids producing flavors and odors

    • Maintains a free, loose, and fluid condition

    • Retains green color

    • Stays aerobic

    Correct Answer
    A. Maintains a free, loose, and fluid condition
    Explanation
    Agitating greensand with an air wash or an air water wash helps to maintain a free, loose, and fluid condition of the filter media. This is beneficial because it prevents the greensand from becoming compacted or clumped together, which could reduce its effectiveness in filtering out impurities. By keeping the greensand in a loose and fluid state, it ensures that water can flow through it easily, allowing for efficient filtration.

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  • 14. 

    Why are suface waters generally free from both iron and manganese?

    • Because algae growth takes up iron and manganese

    • Because iron and manganese are bound up in ground-water

    • Because iron and manganese react with dissolved oxygen to from insoluble compounds

    • Because precipitation collects iron and manganese in the atmosphere

    Correct Answer
    A. Because iron and manganese react with dissolved oxygen to from insoluble compounds
    Explanation
    Surface waters are generally free from both iron and manganese because these elements react with dissolved oxygen to form insoluble compounds. When iron and manganese come into contact with oxygen in water, they undergo oxidation and form solid particles that are not soluble. These particles then settle down and are removed from the surface water, resulting in low levels of iron and manganese.

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  • 15. 

    Why must iron tests be made on water entering a filter?

    • To be sure that ion flavors and odors are not present

    • To be sure the iron is in the ferric state

    • To be sure the iron is in the ferrous state

    • To be sure there is no rust present in the water

    Correct Answer
    A. To be sure the iron is in the ferric state
    Explanation
    Iron tests must be made on water entering a filter to be sure the iron is in the ferric state. This is because ferric iron is insoluble and can be effectively removed by filtration. If the iron is in the ferrous state, it may not be effectively removed by filtration and can cause staining and other issues. Therefore, testing the iron state is important to ensure the effectiveness of the filtration process.

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  • 16. 

    When iron Bacteria form thick slimes on the walls of distribution system mains, what color does the iron give the slimes.

    • Black

    • Blue-green

    • Orange

    • Rust

    Correct Answer
    A. Rust
    Explanation
    When iron bacteria form thick slimes on the walls of distribution system mains, the iron in the slimes gives them a rust color. This is because iron reacts with oxygen in the presence of water, forming iron oxide, commonly known as rust. Therefore, the slimes appear to be rust-colored due to the presence of iron in them.

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  • 17. 

    Why is chlorine usually fed along with polyphosphate when controlling iron and manganese in water?

    • To comply with drinking water regulations

    • To control the release of flavors and odors

    • To co-precipitate the iron

    • To prevent the growth of iron bacteria

    Correct Answer
    A. To prevent the growth of iron bacteria
    Explanation
    Chlorine is usually fed along with polyphosphate when controlling iron and manganese in water to prevent the growth of iron bacteria. Iron bacteria are microorganisms that thrive in environments with high levels of iron. They can cause issues such as clogged pipes, foul odors, and slime build-up. Chlorine is a disinfectant that helps kill bacteria, while polyphosphate helps to inhibit the growth of bacteria by forming a protective coating on the surfaces of pipes and plumbing fixtures. By using both chlorine and polyphosphate, the growth of iron bacteria can be effectively prevented, ensuring the water remains clean and free from bacterial contamination.

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  • 18. 

    How to potassium and permanganate remove iron and manganese from water?

    • By exchanging iron and manganese for other ions

    • By filtering out the iron and manganese

    • By forming insoluble oxides

    • By forming soluble oxides

    Correct Answer
    A. By forming insoluble oxides
    Explanation
    Potassium and permanganate remove iron and manganese from water by forming insoluble oxides. This means that when potassium and permanganate come into contact with iron and manganese in water, they cause a chemical reaction that results in the formation of oxides that are insoluble, or not able to dissolve in water. These insoluble oxides then precipitate out of the water, effectively removing the iron and manganese.

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  • 19. 

    The higher the pH, the longer the time required for aeration to oxidize iron.

    • True

    • False

    Correct Answer
    A. False
    Explanation
    The given statement is false because the higher the pH, the faster the time required for aeration to oxidize iron. This is because a higher pH indicates a more alkaline environment, which promotes the oxidation of iron. In contrast, a lower pH, indicating a more acidic environment, slows down the oxidation process. Therefore, the correct answer is false, as higher pH levels actually decrease the time required for aeration to oxidize iron.

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  • 20. 

    Which methods are available to control iron and manganese in water?

    • Alternate source

    • Oxidation by aeration

    • Oxidation with permangante

    • Phosphate treatment

    • Removal by ion exhange

    Correct Answer(s)
    A. Alternate source
    A. Oxidation by aeration
    A. Oxidation with permangante
    A. Phosphate treatment
    A. Removal by ion exhange
    Explanation
    The available methods to control iron and manganese in water include using an alternate source of water, oxidizing the contaminants through aeration, using permanganate for oxidation, treating with phosphate, and removing the contaminants through ion exchange. These methods can help to reduce the levels of iron and manganese in water, improving its quality and making it safe for consumption.

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  • 21. 

    How can the settled precipitates from a continuous regeneration (CR) greensand process be disposed of?

    • In a sanitary sewer

    • In a storm drain

    • Sent to a drying bed

    • Sent to a lake

    • Sent to a river

    Correct Answer(s)
    A. In a sanitary sewer
    A. Sent to a drying bed
    Explanation
    The settled precipitates from a continuous regeneration greensand process can be disposed of in a sanitary sewer or sent to a drying bed. Disposing of them in a sanitary sewer ensures that the waste is properly treated and does not harm the environment. Sending them to a drying bed allows for further drying and solidification of the precipitates before disposal. Both methods are safe and environmentally friendly ways to handle the waste generated from the process.

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  • 22. 

    If chlorine is used as an oxidizing agent, which reducing agents can be used to dechlorinate the water?

    • Hydrogen sulfide

    • Sodium bisulfite

    • Sodium Chloride

    • Sodium Sulfite

    • Sulfur Dioxide

    Correct Answer(s)
    A. Sodium bisulfite
    A. Sodium Sulfite
    A. Sulfur Dioxide
    Explanation
    Sodium bisulfite, sodium sulfite, and sulfur dioxide can be used as reducing agents to dechlorinate water when chlorine is used as an oxidizing agent. These substances have the ability to react with chlorine and convert it into a less harmful form, thereby removing the chlorine from the water.

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  • 23. 

    When oxidizing iron using aeration, what factors influence the rate of iron oxidation

    • Flows

    • Hardness

    • Organic Substances

    • PH

    • Temperature

    Correct Answer(s)
    A. Organic Substances
    A. pH
    A. Temperature
    Explanation
    The rate of iron oxidation when oxidizing iron using aeration is influenced by organic substances, pH, and temperature. Organic substances can act as catalysts and increase the rate of oxidation. pH affects the solubility of iron and the reaction rate, with higher pH values promoting faster oxidation. Temperature also plays a role, as higher temperatures generally result in faster reactions.

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  • 24. 

    Pre-treatment May be required before a continues regeneration (CR) manganese greensand plant to oxidize and remove which items?

    • Alkalinity

    • Coliforms

    • Hardness

    • Iron

    • Sulfide

    Correct Answer(s)
    A. Iron
    A. Sulfide
    Explanation
    Pre-treatment is necessary before a continuous regeneration manganese greensand plant to oxidize and remove iron and sulfide. Iron and sulfide are common contaminants found in water sources, and they can cause issues such as discoloration, odor, and taste. The manganese greensand plant utilizes a process called oxidation to convert the iron and sulfide into insoluble forms that can be easily removed from the water. This pre-treatment step ensures that the greensand plant operates efficiently and effectively in removing these contaminants from the water supply.

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  • 25. 

    How are greensand filters different than conventional filters?

    • Backwash rate is lower

    • Effluent color is clearer

    • Filtration rate is slower

    • Run time is shorter

    • Sand is finer than conventional filter sand

    Correct Answer(s)
    A. Backwash rate is lower
    A. Filtration rate is slower
    A. Sand is finer than conventional filter sand
    Explanation
    Greensand filters are different from conventional filters in several ways. Firstly, the backwash rate in greensand filters is lower, meaning that less water is required to clean the filter. Secondly, the filtration rate in greensand filters is slower, allowing for more thorough filtration. Additionally, the sand used in greensand filters is finer than the sand used in conventional filters, resulting in better filtration and clearer effluent color. These differences contribute to a shorter run time for greensand filters compared to conventional filters.

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  • 26. 

    When trouble shooting manganese greensand filters, operators should look for what kinds of trouble?

    • Excessive pressure drop across bed immediately after backwashing

    • Filter effluent clear, But manganese higher than raw water

    • Filter effluent turbid with yellow to brownish color

    • Iron low and manganese low

    • On multiple unit installations, water quality good on some units, but bad on other units.

    Correct Answer(s)
    A. Excessive pressure drop across bed immediately after backwashing
    A. Filter effluent clear, But manganese higher than raw water
    A. On multiple unit installations, water quality good on some units, but bad on other units.
    Explanation
    Operators should look for the following kinds of trouble when troubleshooting manganese greensand filters: excessive pressure drop across the bed immediately after backwashing, filter effluent that is clear but has a higher manganese level than the raw water, and water quality that is good on some units but bad on other units in multiple unit installations. These issues indicate potential problems with the filter's performance and can help operators identify and address any issues with manganese removal.

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  • Mar 22, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • May 16, 2017
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    Poghosyanvahagn
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