Podcast
Questions and Answers
What are the two important factors impacting the effectiveness of chlorination?
What are the two important factors impacting the effectiveness of chlorination?
Concentration of chlorine and contact time
The treatment process that controls corrosion or scaling is known as what?
The treatment process that controls corrosion or scaling is known as what?
Stabilization
Permanganate reactions are highly dependent on what factor?
Permanganate reactions are highly dependent on what factor?
pH
It is hardest to kill the organism that causes what illness?
It is hardest to kill the organism that causes what illness?
Disinfection of water wells with free chlorine requires exposure for how long and at what concentration?
Disinfection of water wells with free chlorine requires exposure for how long and at what concentration?
Flocculation basins are usually designed to provide for detention times of how long?
Flocculation basins are usually designed to provide for detention times of how long?
Alum works best in a pH range of what?
Alum works best in a pH range of what?
What has little effect on colloidal particles because of their small size?
What has little effect on colloidal particles because of their small size?
What natural electrical force keeps colloidal particles apart in water treatment?
What natural electrical force keeps colloidal particles apart in water treatment?
What does the zeta potential measure?
What does the zeta potential measure?
What device collects the settled water as it leaves the sedimentation basin?
What device collects the settled water as it leaves the sedimentation basin?
In solid-contact basins with fairly constant water quality parameters, how often should the solids concentration be determined?
In solid-contact basins with fairly constant water quality parameters, how often should the solids concentration be determined?
What is the definition of decant?
What is the definition of decant?
How often should sedimentation basins with mechanical sludge removal equipment be drained and inspected?
How often should sedimentation basins with mechanical sludge removal equipment be drained and inspected?
What is the most important reason to reduce turbidity?
What is the most important reason to reduce turbidity?
What is the filtration flow rate through a manganese greensand pressure filter at 10 degrees C?
What is the filtration flow rate through a manganese greensand pressure filter at 10 degrees C?
When is a filter ripening?
When is a filter ripening?
Virgin greensand can be regenerated by soaking the filter bed for several hours in a chlorine solution of what?
Virgin greensand can be regenerated by soaking the filter bed for several hours in a chlorine solution of what?
What precipitates can foul a cation exchange resin?
What precipitates can foul a cation exchange resin?
What process works best for sequestering manganese?
What process works best for sequestering manganese?
Adding CO2 to water is known as what?
Adding CO2 to water is known as what?
What must be done in the ion-exchange softening process once the resin can no longer soften water?
What must be done in the ion-exchange softening process once the resin can no longer soften water?
What type of analysis, under no circumstances, should a composite sample be collected?
What type of analysis, under no circumstances, should a composite sample be collected?
The number of monthly distribution system chlorine residual samples required is based on what?
The number of monthly distribution system chlorine residual samples required is based on what?
What is the ideal indicator for pathogens?
What is the ideal indicator for pathogens?
When one substance is dissolved in another and will not settle out, what is the product called?
When one substance is dissolved in another and will not settle out, what is the product called?
Acids, bases, and salts lacking in carbon are known as what?
Acids, bases, and salts lacking in carbon are known as what?
What type of violation requires an all clear notification to the public?
What type of violation requires an all clear notification to the public?
How many coliform positive samples are allowed each month from water systems that collect less than 40 samples per month?
How many coliform positive samples are allowed each month from water systems that collect less than 40 samples per month?
If a water sample tests positive for coliforms, the system must collect a set of repeat samples within how many hours?
If a water sample tests positive for coliforms, the system must collect a set of repeat samples within how many hours?
What are the minimum number of service connections/people/days to make up a public water system?
What are the minimum number of service connections/people/days to make up a public water system?
Where are the sampling points located for required sampling of coliform bacteria in community water systems?
Where are the sampling points located for required sampling of coliform bacteria in community water systems?
The main purpose of mechanical seals is to do what?
The main purpose of mechanical seals is to do what?
The purpose of packing is to do what?
The purpose of packing is to do what?
What part of a pump houses the packing or mechanical seal?
What part of a pump houses the packing or mechanical seal?
What is the only type of pump that can be operated against a closed valve?
What is the only type of pump that can be operated against a closed valve?
What is a principal problem associated with the preliminary treatment screening?
What is a principal problem associated with the preliminary treatment screening?
What is the most important thing to consider in automatic startup after a power failure?
What is the most important thing to consider in automatic startup after a power failure?
At what range of temperature will fusible plugs on chlorine cylinders melt?
At what range of temperature will fusible plugs on chlorine cylinders melt?
When should a new gasket be used when a chlorine cylinder is changed out?
When should a new gasket be used when a chlorine cylinder is changed out?
What is the best type of gasket to be used when connecting a chlorine cylinder or container to the chlorine feed system?
What is the best type of gasket to be used when connecting a chlorine cylinder or container to the chlorine feed system?
What part of the human body is the most vulnerable to allowing microorganisms to enter?
What part of the human body is the most vulnerable to allowing microorganisms to enter?
What are the organisms used to indicate the likelihood that pathogenic bacteria may be present?
What are the organisms used to indicate the likelihood that pathogenic bacteria may be present?
What adverse effects does the secondary contaminant manganese have?
What adverse effects does the secondary contaminant manganese have?
In general, what causes an increase in taste and odors when natural waters lack dissolved oxygen?
In general, what causes an increase in taste and odors when natural waters lack dissolved oxygen?
What physical property, as opposed to a chemical property, is important to water treatment?
What physical property, as opposed to a chemical property, is important to water treatment?
What are the two principal chemicals that cause water hardness?
What are the two principal chemicals that cause water hardness?
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Study Notes
Chlorination and Disinfection
- Effectiveness of chlorination depends on concentration of chlorine and contact time.
- Disinfection of water wells requires 12 to 24 hours exposure at 50 mg/L concentration.
- Reducing turbidity is crucial to remove pathogens from water.
Water Treatment Processes
- Stabilization is the treatment process that controls corrosion or scaling.
- Flocculation basins typically designed for detention times of 15 to 45 minutes are essential in removing particles.
- Decanting involves drawing off liquid without disturbing sediment.
Biological and Chemical Considerations
- Cryptosporidiosis is the hardest organism to kill in water treatment processes.
- Permanganate reactions are heavily influenced by pH levels.
- The zeta potential measures excess electrons on particulate matter surfaces, crucial for understanding colloidal behavior.
Filtration and Composition
- Manganese greensand filters operate efficiently at a flow rate of 2 to 3 gpm/sq ft at 10 degrees C.
- Virgin greensand can be regenerated using a chlorine solution of 100 mg/L.
- Cation exchange resin can be fouled by iron and manganese deposits.
Sampling and Monitoring
- Monthly distribution system chlorine residual samples are determined by system size.
- Composite samples should not be used for bacteriological analysis under any conditions.
- Coliform group bacteria are ideal indicators for the presence of pathogens in water.
Mechanical and Pump Operations
- Mechanical seals control water leakage from pump stuffing boxes, while packing manages leakage along the pump's shaft.
- Centrifugal pumps are unique in their ability to operate against closed valves.
- Fusible plugs on chlorine cylinders melt between 157 to 162 degrees F, serving as a safety mechanism to prevent accidents.
Treatment Challenges and Solutions
- Clogging is a principal challenge during preliminary treatment screening.
- Anaerobic decomposition in oxygen-poor waters can lead to increased taste and odors.
- Manganese is a secondary contaminant that can discolor laundry and affect the taste of beverages.
Regulatory and Safety Measures
- A public water system must have a minimum of 15 service connections, serving at least 25 people over 60 days.
- If a water sample tests positive for coliforms, repeat samples are required within 24 hours.
- Annual inspection and draining of sedimentation basins with mechanical sludge removal are necessary for maintaining system integrity.
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