Podcast
Questions and Answers
The objective of the jar test is to find the optimal ______, coagulant dose, and the theoretical amount of alkalinity that would be consumed at the optimal dose.
The objective of the jar test is to find the optimal ______, coagulant dose, and the theoretical amount of alkalinity that would be consumed at the optimal dose.
pH
In the first jar test, the optimal pH chosen was ___.
In the first jar test, the optimal pH chosen was ___.
6.0
The optimal alum dose estimated from the second jar test was about ___ mg/L.
The optimal alum dose estimated from the second jar test was about ___ mg/L.
12.5
To pinpoint the optimal conditions, the laboratory technician would vary the alum dose between ___ and 15 mg/L.
To pinpoint the optimal conditions, the laboratory technician would vary the alum dose between ___ and 15 mg/L.
Signup and view all the answers
From Figure 6-11, the optimum pH was estimated to be ___ and the optimum dose was estimated to be 12.5 mg/L.
From Figure 6-11, the optimum pH was estimated to be ___ and the optimum dose was estimated to be 12.5 mg/L.
Signup and view all the answers
In the jar test, the laboratory technician would probably try to repeat the test using a pH of 6.25 and varying the alum dose between 10 and 15 to pinpoint the ___ conditions.
In the jar test, the laboratory technician would probably try to repeat the test using a pH of 6.25 and varying the alum dose between 10 and 15 to pinpoint the ___ conditions.
Signup and view all the answers
COV is defined as the coefficient of variation with time where COV is the ______ of concentration
COV is defined as the coefficient of variation with time where COV is the ______ of concentration
Signup and view all the answers
The standard deviation is defined as the sum of (Ct minus C) squared divided by n-1, where Ct is the concentration of the sample and n is the number of ______
The standard deviation is defined as the sum of (Ct minus C) squared divided by n-1, where Ct is the concentration of the sample and n is the number of ______
Signup and view all the answers
The design criteria may include a COV of 1 to 10 percent with an average of 5 percent, a Gt range of 350–1700, a mixing time of 1 to 3 s, and a maximum headloss of 0.6 to 0.9 m. The design should specify that the mixing elements be ______
The design criteria may include a COV of 1 to 10 percent with an average of 5 percent, a Gt range of 350–1700, a mixing time of 1 to 3 s, and a maximum headloss of 0.6 to 0.9 m. The design should specify that the mixing elements be ______
Signup and view all the answers
According to Bayer et al. (2003), three elements in mixers designed for turbulent flow will yield a COV of about 10 percent, while six elements will yield a COV of about 1 percent for Reynolds number greater than 5,000. Turbulent flow may be assumed for water entering water treatment plants from ______ sources
According to Bayer et al. (2003), three elements in mixers designed for turbulent flow will yield a COV of about 10 percent, while six elements will yield a COV of about 1 percent for Reynolds number greater than 5,000. Turbulent flow may be assumed for water entering water treatment plants from ______ sources
Signup and view all the answers
The selection process for mixers is highly dependent on the approach suggested by the ______ for their mixer
The selection process for mixers is highly dependent on the approach suggested by the ______ for their mixer
Signup and view all the answers
The method suggested by Bayer et al. (2003) is to select the number of mixing elements to achieve the desired COV, where three elements yield a COV of about 10 percent and six elements yield a COV of about 1 percent for mixers designed for turbulent ______
The method suggested by Bayer et al. (2003) is to select the number of mixing elements to achieve the desired COV, where three elements yield a COV of about 10 percent and six elements yield a COV of about 1 percent for mixers designed for turbulent ______
Signup and view all the answers
Because of the time delay in conducting the test, other techniques such as zeta potential measurements and the use of a streaming current detector (SCD) have been used to augment the ______ test.
Because of the time delay in conducting the test, other techniques such as zeta potential measurements and the use of a streaming current detector (SCD) have been used to augment the ______ test.
Signup and view all the answers
None of these relieve the operator of the necessity of a significant amount of attention. Monitoring of the chemical feed system to detect clogging of the lines and maintenance of the mixers ranks second in the need for close O&M oversight. Appropriate mixing energy is an important part of optimization of the chemical ______.
None of these relieve the operator of the necessity of a significant amount of attention. Monitoring of the chemical feed system to detect clogging of the lines and maintenance of the mixers ranks second in the need for close O&M oversight. Appropriate mixing energy is an important part of optimization of the chemical ______.
Signup and view all the answers
Excess dosing with coagulant to compensate for inefficient mixing not only is uneconomical in terms of chemical usage, it is expensive in terms of ______ production.
Excess dosing with coagulant to compensate for inefficient mixing not only is uneconomical in terms of chemical usage, it is expensive in terms of ______ production.
Signup and view all the answers
All of the design calculations in this chapter were based on the design flow, that is, the maximum daily flow rate at the end of the design life. Because the minimum flow rate at start-up will probably be considerably less than the design flow, operational problems may be severe. It is highly recommended that the design be evaluated at minimum flow ______.
All of the design calculations in this chapter were based on the design flow, that is, the maximum daily flow rate at the end of the design life. Because the minimum flow rate at start-up will probably be considerably less than the design flow, operational problems may be severe. It is highly recommended that the design be evaluated at minimum flow ______.
Signup and view all the answers
Most drive failures are caused when the unit is started at the top rotational speed. O&M manuals should note that mixers should be started at low speed to avoid very high torque force and a high ______ requirement.
Most drive failures are caused when the unit is started at the top rotational speed. O&M manuals should note that mixers should be started at low speed to avoid very high torque force and a high ______ requirement.
Signup and view all the answers
Suggestions from operators include the following: Because of the time delay in conducting the test, other techniques such as zeta potential measurements and the use of a streaming current detector (SCD) have been used to augment the ______ test.
Suggestions from operators include the following: Because of the time delay in conducting the test, other techniques such as zeta potential measurements and the use of a streaming current detector (SCD) have been used to augment the ______ test.
Signup and view all the answers
Study Notes
Coagulation and Flocculation
- The objective of jar testing is to find the optimal pH, coagulant dose, and theoretical amount of alkalinity consumed at the optimal dose.
- A jar test apparatus is used to test different pH and alum dose combinations to determine the optimal conditions for coagulation and flocculation.
Jar Test Results
- The optimal pH was determined to be 6.0 in the first jar test.
- The optimal alum dose was estimated to be around 12.5 mg/L in the second jar test.
Coefficient of Variation (COV)
- COV is defined as the ratio of the standard deviation of concentration to the average concentration, multiplied by 100%.
- COV is used to measure the uniformity of mixing in tanks.
Design Criteria for Mixers
- The design of mixers should specify removable mixing elements for easy cleaning and maintenance.
- The mixing elements should be designed to achieve a COV of 1 to 10% with an average of 5%.
- The maximum headloss should be between 0.6 to 0.9 m.
- The mixing time should be between 1 to 3 seconds.
Selection of Mixers
- The selection of mixers depends on the approach suggested by the manufacturer.
- The number of mixing elements can be selected based on the desired COV.
- Bayer et al. (2003) suggest that three elements will yield a COV of about 10% and six elements will yield a COV of about 1% for mixers designed for turbulent flow.
Operational and Maintenance (O&M) Considerations
- Monitoring of the chemical feed system is crucial to detect clogging of lines and maintenance of mixers.
- Appropriate mixing energy is important for optimization of chemical dose.
- Excess dosing with coagulant can be uneconomical and lead to excess sludge production.
Hints from the Field
- Design calculations should be evaluated at minimum flow conditions to avoid operational problems.
- O&M manuals should specify that mixers should be started at low speed to avoid high torque force and power requirement.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz focuses on determining the optimal pH, coagulant dose, and calculating the theoretical amount of alkalinity consumed during water treatment. It involves analyzing data from jar tests and understanding the process of coagulation and flocculation.
