Questions and Answers
What is contamination?
The introduction into water of microorganisms, chemicals, toxic substances, wastes or wastewater in a concentration that makes the water unfit for its intended use.
Which of the following are chemicals that raise alkalinity? (Select all that apply)
Which of the following chemicals lower alkalinity? (Select all that apply)
What is disinfection?
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What is sterilization?
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What are the four categories of contaminants?
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Name three types of microbial/biological contaminants.
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List five properties of chlorine gas.
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Which of the following are types of chemical disinfectants? (Select all that apply)
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What factors influence disinfection?
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What are physical means of disinfection?
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What is the difference between available free chlorine and combined chlorine?
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What happens when chlorine is added to water?
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What is a hypo-chlorinator?
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What is the purpose of an Amperometric Titration Chlorine Residual Analyzer?
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What is the DPD test?
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What is the purpose of Sodium Thiosulphate in water treatment?
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What are chlorine leak kits used for?
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What happens when ammonia is used for leak detection?
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What does 'adit' refer to?
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What are the treatment steps in water processing?
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What is conventional treatment?
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What does conductivity measure?
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What is the best pH range for coagulation?
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What is sweep coagulation?
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Study Notes
Water Treatment Terminology and Processes
- Contamination involves introducing harmful substances into water, making it unsuitable for intended use.
- Chemicals that raise alkalinity include Hydrated Lime, Caustic Soda, Soda Ash, Calcium Hypochlorite, and Sodium Aluminate.
- Chemicals that lower alkalinity consist of Aluminum Sulfate, Carbon Dioxide, Chlorine Gas, Ferric Chloride, Ferric Sulfate, and Sulfuric Acid.
- Disinfection is the process to kill or inactivate most microorganisms in water, targeting pathogenic bacteria.
- Sterilization completely destroys all microorganisms, including harmful microbes and their spores.
- Categories of contaminants: Physical (e.g., temperature, taste, odor, turbidity), Chemical (e.g., minerals, acids), Biological (e.g., bacteria, viruses, protozoans), and Radiological.
- Types of microbial/bio contaminants: Bacteria, Viruses (smallest), Protozoans (single-celled, motile organisms).
Chlorine and Chemical Disinfection
- Chlorine gas: Greenish-yellow liquid, 2.5 times heavier than air, expands significantly, non-flammable, supports combustion.
- Types of chemical disinfectants: Chlorine (varieties include Chloramines), Iodine, Bromine, Ozone (no residual), and high pH bases.
- Key factors influencing disinfection: pH (lower is better), temperature (higher is better), contact time, and concentration of disinfectants.
- Physical means of disinfection include ultraviolet rays and boiling water.
- Free chlorine refers to the portion of chlorine available for disinfection, while combined chlorine interacts with ammonia or organic nitrogen to assist in oxidization and bacterial kill.
- When chlorine is added to water, it creates Hypochlorous Acid and Hydrochloric Acid, with varying forms dependent on pH.
Equipment and Testing
- A hypo-chlorinator feeds liquid chlorine using a positive displacement pump and solution tank.
- An Amperometric Titration Chlorine Residual Analyzer provides accurate chlorine residual testing results.
- The DPD Test is widely used for measuring free and residual chlorine concentrations.
- Sodium Thiosulphate is utilized to remove chlorine residuals from microbial samples.
- Chlorine leak kits are categorized based on the size of the chlorine container: Cylinder (A), 1-Ton Container (B), Box Car Clean-Up (C).
- Ammonia can indicate chlorine leaks as it produces white smoke.
Water Treatment Steps and Processes
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Treatment steps include:
- Raw water screened to remove debris.
- Prechlorination (optional) to kill organisms and control odor.
- Flash-mixing chemicals with raw water to encourage particle clumping.
- Coagulation and flocculation creating larger particles.
- Suspended particle sedimentation in a basin.
- Filtration for remaining particles.
- Post-chlorination to ensure water safety and provide residual chlorine.
- Chemicals added to control corrosion before water moves into a clear-well for storage and contact time.
- Conventional treatment processes involve coagulation, flocculation, sedimentation, and filtration.
Additional Water Quality Measures
- Conductivity measures a solution's ability to carry an electric current, indicating ion concentrations.
- A streaming current-meter optimizes coagulant doses, working as an online jar-test to match negative charges of particles with positively charged coagulants.
- The best pH range for coagulation is between 5-7.
- Sweep coagulation involves overdosing coagulants to achieve a desired pH range.
Laboratory Procedures
- The Jar Test simulates coagulation processes to determine effective chemical dosing strategies.
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Description
This quiz covers essential terminology and processes related to water treatment. Participants will learn about contamination, various chemicals that affect alkalinity, and methods of disinfection and sterilization. Understand the categories of contaminants and the types of microbial contaminants that can affect water quality.
