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HYDRAULIC HEADLOSS PREDICTIONS AS ITPREDICTIONS AS IT RELATES TO INFLUENT WASTEWATER SCREENS
Michigan Water Environment Wastewater Administrators
C f F k th MIConference Frankenmuth, MI –January 20, 2012
Presented by:Presented by:Steve Aiken
Agendag1. Background on hydraulics
2. Driving Factors why you want the hydraulics righty g
3. Hydraulic modeling and results3. Hydraulic modeling and results
BackgroundgManual screens or comminutors used t b th lto be the only way to remove debris from the influentfrom the influent
Reasons for accurate headloss estimationheadloss estimation
– Allows proper selection of screening equipmentscreening equipment
– Allows proper operation of screening equipmentscreening equipment
– Required to properly size all elements associated with screening equipmentassociated with screening equipment (channel depth and width, geometry, etc.)
BerezinskiBerezinskiBernoulliDarcy WeisbachDarcy-WeisbachHazen-WilliamsKi hKirschmerManning FelleniusSpanglerp gEscandeZimmermanZimmerman
Concerns or Issues to consider:
Slot VelocitSlot Velocity
• As the velocity through the screen increases the debris capture rate decreases
Concerns or Issues to consider:Hydraulic Bottleneck
• There is an increase in headloss with finer screens and the upstream water level a peak flow has to be taken into account
Concerns or Issues to consider:Blinding
Cleaning c cle times ha e to be• Cleaning cycle times have to be considered as the screen can be clean one minute and blinded off theclean one minute and blinded off the next
Testing (cont.)gOriginal coefficientsRe ised coefficientsRevised coefficients
Equation Opening, mm [in]
Bar Shape Trap Rect Tear
Original Kirschmer: 1.4 2.42 0.76g
Kirschmer β 6 [0.25] 1.3 1.2 0.7613 [0.5] 1.7 2.1 1.4
19 [0.75] 2.4 2.42 1.2[ ]Original Bernoulli: 1.42 1.42 1.42
Bernoulli C 6 [0.25] 2.2 2.5 3.513 [0.5] 2 2.1 2.213 [0.5] 2 2.1 2.2
19 [0.75] 1.4 1.5 2.5
Duperon CorporationHead Loss Vs Downstream Water Depth 25%
Bl k dDate: 1/3/2012 Bar Width: 0.25 [In]
4014
BlockedProposal no.: P4584
Description: Missouli WWTPMachine Type: FPFS
Clear Opening: 0.25 [In]Channel Depth: 3.5 FeetChannel Width: 4 FeetMaximum Capture:15.49 [Ft^3/Hr]MontanaSite
Address:
30
35
40
10
12
]
20
25
6
8
Upstream Level [In
Headloss [In]
5
10
15
2
4
U
000 0.5 1 1.5 2 2.5 3 3.5
Downstream Depth [FT]
Average Flow 12.54 MGD Minimum Flow 6 MGD Setteling Threshold 2
Setteling Threshold 3 Upstream level 6 MGD