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Water TreatmentPackage Plant Design

Sedimentation TankDesign

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Sedimentation Tank design

Typical design criteria for horizontal-flow rectangular tanks with tube settlers

MWH pp.823

"Tube settlers typically have detention time less than 20min, but they still have a settling efficientycomparable to that of a rectangular settling tank with a minimum 2h detention time."

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Water TreatmentPackage Plant Design

Sedimentation TankDesign

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General Data

Raw water, Q = MLDRaw water, Q = m3/s

Number of basin = No.

Unit Load = m3/s= MLD

Tube settlers

Length Lp = mWidth d = m

Settling Velocity, Vs = m/s AssumedƟ = 60 degrees

Adopted Parameters

Settling Zone Dimension by trial and error

Width W = m AssumedDepth D = m AssumedLength L = m Assumed

Settling Area, = m2Vf Ɵ = m/sVf Ɵ = m/h < 2.5 to 6.25 m/h

Total TankWidth W = mDepth D = mTotal Length L = m

Tank volume, V = m3 including additional % for settling.Thus, Total length = m

Detention time, T = s= 79 min ( 6 to 10 min.) OK

2.5

0.625

11.50.00206

0.00061

0.05

2.32.4

6.25

6.25

0.0289

4

2.31

0.9

0.00723

34.5

5

4769

25

7.42918

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MWH, pp.810

Design Calculations

Settling Velocity, Vs = m/s Assumed

Countercurrent Settlers

= s

= s

Reynolds Number < 20,000

=

Froude Number > 0.00001

=vf = m/sAx = m2Pw = mv = m2/sg = m/s2Rh = m

1E-067.1

85.906

479.39

0.0006

1598

5.58E-070.0021

5.52

9.810.7775

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Water Treatment Unit Processes: Physical and Chemical pp.590By David W. Hendricks

Submerged Trough Design

Trough Design

Input Load = m3/s (includes both clarifier discharge)

Wash down loss = % Assumed

Est. Trough load = m3/s or MLDMax. over flow Rate, vf = m/s

Area Req. , Ax = m2

Trough width = mwater depth = mFree board = mTrough heigth = m

2.375

11.3

13.3

0.0021

1.211.10.2

0.0289

5

0.0275

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