Up-flow Sludge Blanket Flocculator™

Jim

Wan

Flocculating since 2005®

Coagulation & Flocculation

Coagulation- Charge neutralization and “sweep floc”

Flocculation- Hydraulic shear forces lead to collisions between unstable particles

Sludge Blanket

Acts as a filter to remove turbidity from the influent

Proportional to the hydraulic residence time of the influent

An increased height of the sludge blanket will increase hydraulic time thus allow more floc to get trapped in bigger floc

Why?

Cheap Remove high levels of turbidity Construction materials readily available

Main Goal

Developing alternative treatment technologies for high turbidity drinking water in regions of the world where conventional flocculation, sedimentation, filtration processes are not yet sustainable

Research Objectives

Test the ability for a self-forming conical system to produce flocculent at a varying up-flow velocity

Find the optimum height of sludge blanket

Methods

Varying Flow Rates Varying Sludge

Blanket Height See Diagram

Tap Water Qtap

P P P

T

Alum Qa

Clay Qc

Sludge Blanket

Calculations

output output input inputQ C Q Cml

min200output total tap clay alum tapQ Q Q Q Q Q

argoutput t etC C

arg

ml mg g

min L L

ml

min

250 40 20

0.5

tap t et alum alum

alum

alum

Q C Q C

Q

Q

arg

ml mg ml

min L min

g

L

250 200 1.75

where 3.5

28.57

tap t et clay clay

clay

clay

alum

clay

Q C Q C

C

Q

Q

C

Alum Calculation Clay Calculation

Experimental Setup

Summary of ExperimentDate Flow Rate (ml/min) Sludge Blanket Height

Tap Water Clay Alum (cm)

14-Nov 250 1.75 0.5 -

16-Nov 250 1.75 0.5 34

18-Nov 250 1.75 0.5 40

20-Nov 250 1.75 0.5 45

22-Nov 250 1.75 0.5 45

23-Nov 300 2.1 0.6 45

24-Nov 350 2.45 0.7 45

28-Nov 400 2.8 0.8 45

29-Nov 500 3.5 1 45

30-Nov 600 4.2 1.2 45

30-Nov 100 0.7 0.2 45

1-Dec 250 1.75 0.5 25

2-Dec 200 1.4 0.4 45

3-Dec 150 1.05 0.3 45

Results Effects of Sludge Blanket Height on Final Turbidity

0

5

10

15

20

25

30

35

40

10000 15000 20000 25000 30000

Time (s)

Tu

rbid

ity

(NT

U)

25 cm

34 cm

40 cm

45 cm

Results Effects of Sludge Blanket Height on Final Turbidity

0

5

10

15

20

25

30

35

20 30 40 50

Height of sludge blanket (cm)

Fin

al T

urbi

dity

(NT

U)

Results Effects of Up-flow Velocity on Final Turbidity

Flow RateUp-flow

Velocity

ml/min m/d

100 19.27

150 28.90

200 38.53

250 48.17

300 57.80

350 67.44

400 77.07

500 96.34

600 115.60

0

10

20

30

10000 20000 30000

Time (s)

Tu

rbid

ity

(NT

U)

150 ml/min

200 ml/min

250 ml/min

300 ml/min

350 ml/min

400 ml/min

500 ml/min

600 ml/min

Results Effects of Up-flow Velocity on Final Turbidity

0

5

10

15

20

25

30

0 20 40 60 80 100 120

Up-flow Velocity (m/d)

Fin

al T

urb

idit

y (N

TU

)

Hydraulic Residence Time

Flow rateUp-flow

VelocityHRT

Sludge height

HRT

ml/min m/d min cm min

100 19.26 33.63 25 7.47

150 28.90 22.42 34 10.16

200 38.53 16.82 40 11.96

250 48.16 13.45 45 13.45

300 57.80 11.21

350 67.43 9.61

400 77.06 8.41

500 96.33 6.73

600 115.6 5.61

Results

0

5

10

15

20

25

30

35

4 9 14 19 24

Hydraulic residence time (min)

Fin

al t

urb

idit

y (N

TU

)

sludge blanket exp flow rate exp

Conclusion

Sludge blanket acts as unstable filter Flow rates 300-400 ml/min (Up-flow

velocity of 57-77 m/d) are optimum Sludge blanket height is important Creating flocs without

mechanical/hydraulic mixing

Future work

Different location, different characteristics• pH, Alkalinity (coagulant chemistry)

Phosphorus + alum

Density formation of flocs• Solid retention time

Different influent turbidity

3 34 4n

nAl H PO AlPO s nH

References [1] Tchobanoglous, G., Burton, F., and H. Stensel. (2003). Wastewater

Engineering: Treatment and Reuse, 4th ed., McGraw Hill, New York. [2] Zeta-Meter, Inc. (1993). Everything You Need to Know About

Coagulation and Flocculation, 4th ed., Zeta-Meter, Inc, Virginia. http://www.zeta-meter.com/coag.pdf

[3] Luu, Kim. (2000). Study of Coagulation and Settling Processes for Implementation in Nepal, Massachusetts Institute of Technology. http://web.mit.edu/watsan/Docs/Student%20Theses/Nepal/Luu2000.pdf

[4] Rog K. and M. Wilson. (2005). Jar Test for Laboratory Research in Environmental Engineering. In press.

[5] Yukselen, M.A. and J. Gregory. (2002). Breakage and Re-formation of alum flocs. Environmental Engineering Science. 19 (4), 229.

[6] Lee, C.C. and S. Dar Lin (eds.). (2000). Handbook of Environmental Engineering Calculations, McGraw Hill, New York.

Acknowledgement

Monroe Weber-Shirk Everyone