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Questions and Answers
What is a primary purpose of water treatment?
What is a primary purpose of water treatment?
Which of the following statements about turbidity is true?
Which of the following statements about turbidity is true?
What is a common contaminant that can be excreted by animals?
What is a common contaminant that can be excreted by animals?
Which oxidant is most commonly used in water treatment?
Which oxidant is most commonly used in water treatment?
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What is the main effect of adding potassium permanganate during oxidation?
What is the main effect of adding potassium permanganate during oxidation?
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Which of the following factors can slow down oxidation in water treatment?
Which of the following factors can slow down oxidation in water treatment?
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What is the purpose of coagulation in water treatment?
What is the purpose of coagulation in water treatment?
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What can be a potential negative consequence of using chlorine as an oxidant?
What can be a potential negative consequence of using chlorine as an oxidant?
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What term describes organic carbon that is smaller than 0.45 micrometers?
What term describes organic carbon that is smaller than 0.45 micrometers?
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Which of the following is NOT a common coagulant?
Which of the following is NOT a common coagulant?
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What is the role of stability factors in colloids?
What is the role of stability factors in colloids?
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Which factor does NOT influence coagulation?
Which factor does NOT influence coagulation?
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What type of polymers have a positive charge?
What type of polymers have a positive charge?
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During the simplest coagulation process, what is produced when Alum is added to water?
During the simplest coagulation process, what is produced when Alum is added to water?
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What does alkalinity measure in water?
What does alkalinity measure in water?
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Which mixing system requires additional electric power for coagulant injection?
Which mixing system requires additional electric power for coagulant injection?
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Study Notes
Introduction to Water Treatment
- Two main reasons for water treatment: remove contaminants harmful to health and improve aesthetic qualities (appearance, color, taste).
- Contaminants affecting taste and odor include hydrogen sulfide gas (rotten egg odor), turbidity (scattering of light), and hardness (calcium and manganese ions).
Most Common Contaminants
- Giardia (6-18 micrometers): excreted by animals.
- Cryptosporidium (4-6 micrometers): also excreted by animals.
- Total Trihalomethanes (TTHM): formed when natural organic substances from decaying vegetation react with chlorine.
- Five Haloacetic Acids (HAA5): also formed from reactions between chlorine and natural organic matter.
Basic Water Treatment Unit Processes
- Biological Activated Carbon: removes contaminants from potable water.
- Oxidation: removes inorganic contaminants like iron, manganese, and arsenic. This process also improves removal of particulates, taste, and odor.
- Chlorine is commonly used in gas, solid, and liquid form. Potassium permanganate is a granular solid, dissolved in water. Factors affecting oxidation speed include pH, oxidant type, and contaminant concentrations. Lower pH or temperature slow oxidation.
- Chlorine use can produce disinfection byproducts like total trihalomethanes (TTH) or Haloacetic acids (HAA5). Ammonia may form chloramines. Chloramines are a weaker oxidant and lead to slower oxidation.
Coagulation
- Destabilizes or decreases stability of colloids (hydrophobic and hydrophilic) in water. Common coagulants include aluminum sulfate, sodium aluminate, ferric sulfate, ferrous sulfate, ferric chloride, polyaluminum chloride, and cationic polymers.
- Dissolved Organic Carbon (DOC): fraction of organic material smaller than 0.45 micrometers.
- Various factors affect coagulation, including pH, turbidity, temperature, and alkalinity. Effective treatment often requires coagulants to be thoroughly dispersed within 1-2 seconds.
- Common types of flash mixers include pump diffusion systems, static inline systems.
Jar Test Apparatus
- Used to determine the correct chemical dosage of coagulants.
- Multiple samples of water, along with various dosages, are used in the process.
- The correct dosage is determined by observing the best flocculation (floc formation). It is best to record pH and turbidity levels.
- Flocculation, disinfection, and sedimentation are additional steps in the treatment process.
- Flocculation involves gently stirring the water. Disinfection controls pathogenic organisms.
- Sedimentation involves removal of solid particles through settling.
- Adsorption is the process of a substance gathering on the surface of a solid.
- Precipitation occurs when a solid substance is formed from a liquid phase.
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Description
This quiz covers the fundamentals of water treatment, focusing on its necessity for health and aesthetic improvements. It explores common contaminants like Giardia and Cryptosporidium, as well as key treatment processes such as biological activated carbon and oxidation. Test your knowledge on maintaining safe and clean water!
