1. [Settling tank/clarifier design] An outlet stream from an aeration tank is fed to a circular settling tank (aka sedimentation tank or clarifier). The stream has a sludge concentration of 3340 mg L-1 and the SSVI of the sludge is 110 L kg-¹. a) To ensure that the maximum underflow velocity is not surpassed, what is the maximum actual sludge flux in the sedimentation tank (Fa), assuming a constant overflow velocity (velocity of clarified effluent coming out of settling tank) of 1.2 m h-¹? [Ans: 6.4 kg m² h-¹] b) Calculate the maximum sludge flux that the sedimentation tank can handle during normal hindered settling (Fp). Assuming that the settling tank operates at Fa = 0.8xFp and at an underflow velocity of 0.575 m h¹, calculate the new velocity of clarified effluent coming out of settling tank? [Ans: = 0.777 m h¹] c) Assume that a single settling tank is used and that the settling tank operates at the conditions defined in part (b). Assume also that the area required for the stilling box is 10% of the area required for settling (As). For a value of clarified effluent flow rate of 1000 m³ day¹ what should be the (average) diameter of the settling tank? [Ans: D = 8.67 m] ● Supplementary information: Note: overflow velocity or velocity of clarified effluent coming out of settling tank is equal to Qe/As, with Qe in m³ h-¹. • Equations: Fp=306.9[SSVI]-0.77 Fa = = [l₁ ++ Qr] x As = 1.5- "max where Fp Qu As Qu/As SSVI Fa Q Q₁ X SSVI 140 0.68 maximum sludge flux the sedimentation tank can handle during normal hindered settling (kg m-²h-¹) underflow flow rate from settling tank (m³ h-¹) sedimentation area of the settling tank (m²) underflow velocity from settling tank (m h-¹) SSVI value (L kg-¹) measured at a sludge concentration of 3500 mg L-1 actual sludge flux (kg m-²h-¹) inlet flow rate to the activated sludge process (see lecture 5) (m³ h-¹) recycle flow rate (see lecture 5) (m³ h-1) solids/sludge concentration (kg m-³)
1. [Settling tank/clarifier design] An outlet stream from an aeration tank is fed to a circular settling tank (aka sedimentation tank or clarifier). The stream has a sludge concentration of 3340 mg L-1 and the SSVI of the sludge is 110 L kg-¹. a) To ensure that the maximum underflow velocity is not surpassed, what is the maximum actual sludge flux in the sedimentation tank (Fa), assuming a constant overflow velocity (velocity of clarified effluent coming out of settling tank) of 1.2 m h-¹? [Ans: 6.4 kg m² h-¹] b) Calculate the maximum sludge flux that the sedimentation tank can handle during normal hindered settling (Fp). Assuming that the settling tank operates at Fa = 0.8xFp and at an underflow velocity of 0.575 m h¹, calculate the new velocity of clarified effluent coming out of settling tank? [Ans: = 0.777 m h¹] c) Assume that a single settling tank is used and that the settling tank operates at the conditions defined in part (b). Assume also that the area required for the stilling box is 10% of the area required for settling (As). For a value of clarified effluent flow rate of 1000 m³ day¹ what should be the (average) diameter of the settling tank? [Ans: D = 8.67 m] ● Supplementary information: Note: overflow velocity or velocity of clarified effluent coming out of settling tank is equal to Qe/As, with Qe in m³ h-¹. • Equations: Fp=306.9[SSVI]-0.77 Fa = = [l₁ ++ Qr] x As = 1.5- "max where Fp Qu As Qu/As SSVI Fa Q Q₁ X SSVI 140 0.68 maximum sludge flux the sedimentation tank can handle during normal hindered settling (kg m-²h-¹) underflow flow rate from settling tank (m³ h-¹) sedimentation area of the settling tank (m²) underflow velocity from settling tank (m h-¹) SSVI value (L kg-¹) measured at a sludge concentration of 3500 mg L-1 actual sludge flux (kg m-²h-¹) inlet flow rate to the activated sludge process (see lecture 5) (m³ h-¹) recycle flow rate (see lecture 5) (m³ h-1) solids/sludge concentration (kg m-³)
Introduction to Chemical Engineering Thermodynamics
8th Edition
ISBN:9781259696527
Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Chapter1: Introduction
Section: Chapter Questions
Problem 1.1P
Related questions
Question
100%
![1. [Settling tank/clarifier design] An outlet stream from an aeration tank is fed to a circular settling
tank (aka sedimentation tank or clarifier). The stream has a sludge concentration of 3340 mg L-1
and the SSVI of the sludge is 110 L kg-¹.
a) To ensure that the maximum underflow velocity is not surpassed, what is the maximum actual
sludge flux in the sedimentation tank (Fa), assuming a constant overflow velocity (velocity of
clarified effluent coming out of settling tank) of 1.2 m h-¹?
[Ans: 6.4 kg m2 h-¹]
b) Calculate the maximum sludge flux that the sedimentation tank can handle during normal
hindered settling (Fp). Assuming that the settling tank operates at Fa = 0.8xFp and at an
underflow velocity of 0.575 m h¹, calculate the new velocity of clarified effluent coming out of
settling tank?
[Ans: = 0.777 m h¨¹]
c) Assume that a single settling tank is used and that the settling tank operates at the conditions
defined in part (b). Assume also that the area required for the stilling box is 10% of the area
required for settling (As). For a value of clarified effluent flow rate of 1000 m³ day-¹ what should
be the (average) diameter of the settling tank?
[Ans: D = 8.67 m]
Supplementary information:
Note: overflow velocity or velocity of clarified effluent coming out of settling tank is equal to
Qe/As, with Qe in m³ h-¹.
Equations:
Fp = 306.9[SSVI]-⁰.
= [Q₁ + Qr] x
Aç
= 1.5-
Fa
[2]
max
where
23 200×
-0.77
SSVI
140
0.68
maximum sludge flux the sedimentation tank can handle during normal hindered settling (kg m-²h-¹)
underflow flow rate from settling tank (m³ h-¹)
sedimentation area of the settling tank (m²)
Qu/As underflow velocity from settling tank (m h-¹)
SSVI SSVI value (L kg-¹) measured at a sludge concentration of 3500 mg L-1
actual sludge flux (kg m-²h-¹)
inlet flow rate to the activated sludge process (see lecture 5) (m³ h-¹)
recycle flow rate (see lecture 5) (m³ h-1)
solids/sludge concentration (kg m-³)](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fde55ad6b-27eb-44c5-bca1-afdb32f2dfc7%2F69796427-15ca-4c01-9b0f-8b8579140f65%2Fgcnrv1r_processed.png&w=3840&q=75)
Transcribed Image Text:1. [Settling tank/clarifier design] An outlet stream from an aeration tank is fed to a circular settling
tank (aka sedimentation tank or clarifier). The stream has a sludge concentration of 3340 mg L-1
and the SSVI of the sludge is 110 L kg-¹.
a) To ensure that the maximum underflow velocity is not surpassed, what is the maximum actual
sludge flux in the sedimentation tank (Fa), assuming a constant overflow velocity (velocity of
clarified effluent coming out of settling tank) of 1.2 m h-¹?
[Ans: 6.4 kg m2 h-¹]
b) Calculate the maximum sludge flux that the sedimentation tank can handle during normal
hindered settling (Fp). Assuming that the settling tank operates at Fa = 0.8xFp and at an
underflow velocity of 0.575 m h¹, calculate the new velocity of clarified effluent coming out of
settling tank?
[Ans: = 0.777 m h¨¹]
c) Assume that a single settling tank is used and that the settling tank operates at the conditions
defined in part (b). Assume also that the area required for the stilling box is 10% of the area
required for settling (As). For a value of clarified effluent flow rate of 1000 m³ day-¹ what should
be the (average) diameter of the settling tank?
[Ans: D = 8.67 m]
Supplementary information:
Note: overflow velocity or velocity of clarified effluent coming out of settling tank is equal to
Qe/As, with Qe in m³ h-¹.
Equations:
Fp = 306.9[SSVI]-⁰.
= [Q₁ + Qr] x
Aç
= 1.5-
Fa
[2]
max
where
23 200×
-0.77
SSVI
140
0.68
maximum sludge flux the sedimentation tank can handle during normal hindered settling (kg m-²h-¹)
underflow flow rate from settling tank (m³ h-¹)
sedimentation area of the settling tank (m²)
Qu/As underflow velocity from settling tank (m h-¹)
SSVI SSVI value (L kg-¹) measured at a sludge concentration of 3500 mg L-1
actual sludge flux (kg m-²h-¹)
inlet flow rate to the activated sludge process (see lecture 5) (m³ h-¹)
recycle flow rate (see lecture 5) (m³ h-1)
solids/sludge concentration (kg m-³)
Expert Solution
This question has been solved!
Explore an expertly crafted, step-by-step solution for a thorough understanding of key concepts.
Step by step
Solved in 5 steps with 5 images
Recommended textbooks for you
Introduction to Chemical Engineering Thermodynami…
Chemical Engineering
ISBN:
9781259696527
Author:
J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:
McGraw-Hill Education
Elementary Principles of Chemical Processes, Bind…
Chemical Engineering
ISBN:
9781118431221
Author:
Richard M. Felder, Ronald W. Rousseau, Lisa G. Bullard
Publisher:
WILEY
Elements of Chemical Reaction Engineering (5th Ed…
Chemical Engineering
ISBN:
9780133887518
Author:
H. Scott Fogler
Publisher:
Prentice Hall
Introduction to Chemical Engineering Thermodynami…
Chemical Engineering
ISBN:
9781259696527
Author:
J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:
McGraw-Hill Education
Elementary Principles of Chemical Processes, Bind…
Chemical Engineering
ISBN:
9781118431221
Author:
Richard M. Felder, Ronald W. Rousseau, Lisa G. Bullard
Publisher:
WILEY
Elements of Chemical Reaction Engineering (5th Ed…
Chemical Engineering
ISBN:
9780133887518
Author:
H. Scott Fogler
Publisher:
Prentice Hall
Industrial Plastics: Theory and Applications
Chemical Engineering
ISBN:
9781285061238
Author:
Lokensgard, Erik
Publisher:
Delmar Cengage Learning
Unit Operations of Chemical Engineering
Chemical Engineering
ISBN:
9780072848236
Author:
Warren McCabe, Julian C. Smith, Peter Harriott
Publisher:
McGraw-Hill Companies, The