Christopher Hill December 6, 2006 CE 679 Application of Ballast Flocculation for Sanitary Sewer...
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Transcript of Christopher Hill December 6, 2006 CE 679 Application of Ballast Flocculation for Sanitary Sewer...
Christopher HillDecember 6, 2006
CE 679
Application of Ballast Flocculation for Sanitary
Sewer Overflow Management
North Dakota State University
Outline• Problem Overview
• Introduction
• Application
• Design
• Conclusion
Problem Overview
• What are SSOs?
• What is the cause of SSOs?
• Why are SSOs a problem?
• What is the frequency of SSOs?
• How are SSOs managed?
Ballasted Flocculation
• What is ballasted flocculation?
• Why ballasted flocculation?
• Actiflo®, DensaDeg®, Sirofloc®
Actiflo® System
Application – Satellite
Basin
Interceptor Sewer
WWTP
River
Actiflo
Disinfection
Sludge
Actiflo®
Screen
• Located in the collection system
• Does not meet EPA secondary treatment standards
• Cost effective
Application – WWTP Bypass
Headworks
River
Disinfection
Actiflo®
• Located at WWTP
• Mixing with the WWTP effluent to comply with permitting limits
• Cost effective
Secondary Treatment
Design – Flow MonitoringBasin 8
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00
Time (hr)
Flo
w (
mg
d)
0.0
1.0
06/11/20010.92 inches/hr
Ra
in F
all
(in
)
Wet-Day Flow Dry-Day Flow Rain Fall
Inflow
Infiltration
• Base on flow monitoring, develop model for sewer system.
• Typically designed for 5 year return period storm
• Design peak wet weather flow = 15 MGD
Design - Pretreatment
• Design Flow– Ramp-up 150% Q– Ramp-down 50% Q– Hydraulically 200%
Q
• Pretreatment– Screening
(3 – 6 mm)– 2 x 10 MGD
Q = 10 MGD
2 x 5 MGD
Design – Coagulation
• Coagulation– Chemical Coagulant – HRT 1 – 2 minutes– Rapid Mixing
(G = 500-1500 s-1)
V
PG
Jar Test/Pilot Study
Sizing TankV = (HRT) x Q = 1 min x 3472.5 gal/min = 3472.5 gal or 464.2 ft3
Mixing
Theoretical Power Requirement
P = G2 V = 12002(1.307x10-3 N*s/m2)13.2m3
= 24,844 W or 25 kW
Design – Flocculation
• Flocculation– Polymer– Sand (2 – 4 g/L)– HRT 1 – 2 minutes– Rapid Mixing
(G = 500-1500 s-1)
V
PG
Jar Test/Pilot Study
Sizing TankV = (HRT) x Q = 1 min x 3472.5 gal/min = 3472.5 gal or 464.2 ft3
Mixing
Theoretical Power Requirement
P = G2 V = 12002(1.307x10-3 N*s/m2)13.2m3
= 24,844 W or 25 kW
Design – Maturation
• Maturation– HRT 3 – 5 minutes – Slow Mixing
(G = 160 – 200 s-1)
Sizing TankV = (HRT) x Q = 3 min x 3472.5 gal/min
= 10,417 gal or 1,393 ft3
Mixing
Theoretical Power Requirement
P = G2 V
= 2002(1.307x10-3 N*s/m2)52.6m3
= 2,750 W or 2.8 kW
Design - Settler• Settler
– Overflow Rate 20 to 80 gal/ft2*min
– Typically 30 gal/ft2*min– Length: Width = 1:1 – Lamellar Tubes
Tank AreaA = Q / Vo
= 3472.5 gal/min / 30 gal/ft2*min = 115.75 ft2
Tank DimensionsL = W = A1/2
= 115.751/2
= 10.75 ft Use 11 ft
Design Criteria Between 45o and 60o InclineNominal Spacing 2 inIncline Length 3 to 6 ft
Design – Actiflo® System
• Assume Depth of 12 ft
Design - Microsand
4.8% of Q Sludge
Actiflo®
Influent Q
Hydrocyclone
1.2% of QRecycled
Sand
River
Clarified Water 6% of Q
Sludge Handling
WWTP
• 2 – 4 g/L of Microsand• Total Volume – Coagulation = 3,375 ft3 or 95,600 L• The system requires 191.2 - 382.4 kg (421.5 - 843 lb)• Sludge = 10 MGD x 0.048 = 480,000 gal/day
Actiflo® Design
Actiflo® Design
Conclusions• Evaluation of Alternatives• Design• Pilot Study• Disadvantages
Questions?