Podcast
Questions and Answers
The two most important factors impacting the effectiveness of chlorination are?
The two most important factors impacting the effectiveness of chlorination are?
- pH and temperature of the water
- concentration of chlorine and the content of foreign substances in the water
- concentration of chlorine and contact time (correct)
- pH of the water and the content of foreign substances in the water
The treatment process that controls corrosion or scaling is known as?
The treatment process that controls corrosion or scaling is known as?
- chemical control
- passivation
- stabilization (correct)
- corrosion kinetics
Permanganate reactions are highly dependent upon?
Permanganate reactions are highly dependent upon?
- alkalinity
- pH (correct)
- organics in the water
- temperature
It is hardest to kill the organism that causes which one of the following illnesses?
It is hardest to kill the organism that causes which one of the following illnesses?
Disinfection of water wells with free chlorine requires exposure for ____ at a concentration of ----?
Disinfection of water wells with free chlorine requires exposure for ____ at a concentration of ----?
Which index determines the calcium carbonate deposition property of water?
Which index determines the calcium carbonate deposition property of water?
The advantage to using the oxidant ozone is that it?
The advantage to using the oxidant ozone is that it?
Pretreatment with chlorine is being eliminated at many water treatment plants because it has been shown to?
Pretreatment with chlorine is being eliminated at many water treatment plants because it has been shown to?
CTs are based on?
CTs are based on?
If the natural fluoride content of the raw water is variable, the concentration should be measured?
If the natural fluoride content of the raw water is variable, the concentration should be measured?
Which is the primary drawback for facilities that use ultraviolet light to disinfect water?
Which is the primary drawback for facilities that use ultraviolet light to disinfect water?
Potassium permanganate is most effective in?
Potassium permanganate is most effective in?
Chlorine is advantageous over chloramines in that chlorine?
Chlorine is advantageous over chloramines in that chlorine?
Which oxidant has the potential of producing ClO3 by-products?
Which oxidant has the potential of producing ClO3 by-products?
How thick should the layer of sodium fluoride crystals be maintained in a saturator tank for flows of less than 100 gpm?
How thick should the layer of sodium fluoride crystals be maintained in a saturator tank for flows of less than 100 gpm?
Which disinfectant would work best against Cryptosporidium?
Which disinfectant would work best against Cryptosporidium?
Which chemical oxidant would be best to use for controlling trihalomethanes formation potential?
Which chemical oxidant would be best to use for controlling trihalomethanes formation potential?
Ozone generators must be supplied with?
Ozone generators must be supplied with?
A conventional treatment plant has raw water with high organic content. What are the most probable oxidants and disinfectants to use?
A conventional treatment plant has raw water with high organic content. What are the most probable oxidants and disinfectants to use?
If air is used to generate ozone, which percentage of the air is usually converted to ozone?
If air is used to generate ozone, which percentage of the air is usually converted to ozone?
Detention time in flocculation basins are usually designed to provide for?
Detention time in flocculation basins are usually designed to provide for?
Alum works best in a pH range of?
Alum works best in a pH range of?
Which statement is true concerning colloidal particles?
Which statement is true concerning colloidal particles?
Which natural electrical force keeps colloidal particles apart in water treatment?
Which natural electrical force keeps colloidal particles apart in water treatment?
The zeta potential measures the number of excess ____ found on the surface of all particulate matter.
The zeta potential measures the number of excess ____ found on the surface of all particulate matter.
Low temperature water can be compensated for when using alum by?
Low temperature water can be compensated for when using alum by?
Which is the optimal pH range for the removal of particulate matter when using alum as a coagulant?
Which is the optimal pH range for the removal of particulate matter when using alum as a coagulant?
Which forces will pull particles together once they have been destabilized in the coagulation-flocculation process?
Which forces will pull particles together once they have been destabilized in the coagulation-flocculation process?
Which is a common mistake that operators make in regards to flocculation units?
Which is a common mistake that operators make in regards to flocculation units?
Ferric sulfate has which advantage over aluminum sulfate (alum)?
Ferric sulfate has which advantage over aluminum sulfate (alum)?
How much alkalinity as CaCO3 will dry-basis alum consume?
How much alkalinity as CaCO3 will dry-basis alum consume?
Natural zeolites that have become exhausted with use are regenerated by immersing them in a strong solution of which chemical?
Natural zeolites that have become exhausted with use are regenerated by immersing them in a strong solution of which chemical?
The zeta potential on a particular sample of water is -2. The degree of coagulation is best described as?
The zeta potential on a particular sample of water is -2. The degree of coagulation is best described as?
Which is a disadvantage of using static mixers?
Which is a disadvantage of using static mixers?
Which is the usual effective pH range of iron salt coagulants?
Which is the usual effective pH range of iron salt coagulants?
Which is the minimum recommended number of flocculation basins?
Which is the minimum recommended number of flocculation basins?
Which type of polymer(s) is (are) sometimes formulated with regulated substances?
Which type of polymer(s) is (are) sometimes formulated with regulated substances?
Which is the most probable solution if rotifers are visible in the finished water?
Which is the most probable solution if rotifers are visible in the finished water?
The best addition for water that is highly colored due to organic matter would be?
The best addition for water that is highly colored due to organic matter would be?
If the activation process of silica is not carefully controlled, what could happen?
If the activation process of silica is not carefully controlled, what could happen?
Which device collects the settled water as it leaves the sedimentation basin?
Which 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?
The definition of decant is?
The definition of decant is?
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?
Which is the most important reason to reduce turbidity?
Which is the most important reason to reduce turbidity?
If enteric disease-causing protozoans have been found in the effluent of a water plant, what is the most probable solution?
If enteric disease-causing protozoans have been found in the effluent of a water plant, what is the most probable solution?
Which is the major cause of short circuiting in a sedimentation basin?
Which is the major cause of short circuiting in a sedimentation basin?
Conventional sedimentation has a ___ removal of Cryptosporidium oocysts.
Conventional sedimentation has a ___ removal of Cryptosporidium oocysts.
In solids-contact basins, the weir loading normally should not exceed ____ of weir length.
In solids-contact basins, the weir loading normally should not exceed ____ of weir length.
Dissolved-air flotation is particularly good for removing?
Dissolved-air flotation is particularly good for removing?
Which determines whether colloidal-sized particles in suspension repel each other, stay in suspension, or agglomerate?
Which determines whether colloidal-sized particles in suspension repel each other, stay in suspension, or agglomerate?
If the sludge in a sedimentation basin becomes too thick, what could happen?
If the sludge in a sedimentation basin becomes too thick, what could happen?
In basins using tube and plate settlers, which parameter must be better than conventional treatment basins?
In basins using tube and plate settlers, which parameter must be better than conventional treatment basins?
Which type of sedimentation basins have the flow of water admitted at an angle?
Which type of sedimentation basins have the flow of water admitted at an angle?
At which minimum angle must self-cleaning tube settlers be placed?
At which minimum angle must self-cleaning tube settlers be placed?
If nematodes are interfering with the disinfectant, what is the most probable solution?
If nematodes are interfering with the disinfectant, what is the most probable solution?
At which angle should the parallel inclined plates be installed when using the shallow-depth sedimentation method?
At which angle should the parallel inclined plates be installed when using the shallow-depth sedimentation method?
Why do solids-contact basins have much shorter detention times than conventional treatment basins?
Why do solids-contact basins have much shorter detention times than conventional treatment basins?
The pulsating energy in a pulsator clarifier helps to?
The pulsating energy in a pulsator clarifier helps to?
Pulsator clarifiers are used to treat water that is?
Pulsator clarifiers are used to treat water that is?
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Study Notes
Water Treatment and Disinfection Processes
- Chlorination Effectiveness: Dependent on chlorine concentration and contact time.
- Corrosion Control: Stabilization is the treatment process that prevents corrosion and scaling.
- Permanganate Reactions: Highly influenced by the pH of the water.
- Pathogen Resistance: Cryptosporidiosis is the disease hardest to eliminate from water.
Disinfection Procedures
- Chlorine Exposure: Requires 12 to 24 hours at a concentration of 50 mg/L for water wells.
- Langelier Saturation Index: Determines water's calcium carbonate deposition potential; negative values indicate corrosive water.
- Ozone as an Oxidant: Holds advantages due to minimal effects on pH compared to other disinfectants.
Chemical Properties and Usage
- Chlorination Drawbacks: Can produce carcinogenic disinfection by-products, prompting alternative methods.
- CT Values: Calculated using chlorine concentration, contact time, pH, and temperature.
- Fluoride Monitoring: Should be measured daily if its concentration varies in raw water.
UV Disinfection Challenges
- Ultraviolet Light Limitations: UV systems may fail to inactivate all microorganisms due to potential light obstruction.
Oxidants and Coagulants
- Potassium Permanganate: Most effective for removing iron from water.
- Chlorine Advantages: Stronger oxidant than chloramines, thereby more effective in disinfection.
- Chemical Control of Trihalomethanes: Chlorine dioxide is preferable for managing formation potential.
Flocculation and Sedimentation
- Flocculation Process: Detention times in basins typically range from 15 to 45 minutes to facilitate proper floc formation.
- Alum Effectiveness: Optimal pH range for alum is 5.8 to 8.5 for effective coagulation.
- Colloidal Behavior: Zeta potential influences whether colloidal particles repel or agglomerate in the water.
Sludge Management
- Sedimentation Basin Management: Sludge should be drained and inspected annually to ensure effective operation.
- Short Circuiting Causes: Poor inlet baffling is the primary reason for inefficient sedimentation.
Equipment and Testing
- Effluent Launder: Device that collects water after it has settled in sedimentation basins.
- Tube Settlers: Require better floc settling characteristics than conventional basins for effective performance.
Process Optimization
- Algal Issues: Efficient removal of algae achieved through dissolved-air flotation techniques.
- Flocculation Optimization: Adjustments during flocculation time can improve water treatment efficacy.
General Water Treatment Principles
- Turbidity Reduction: A key goal is to decrease turbidity to eliminate pathogens effectively.
- Organic Matter Treatment: The addition of acid prior to coagulation helps address high organic color in water.
Nematodes and Clarification
- Nematode Interference: Solutions involve optimizing the settling process to mitigate their impact on disinfection.
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