basics on screening and hydraulics...basics on screening and hydraulics mwea lagoon committee may...
TRANSCRIPT
Basics on Screening
and Hydraulics
MWEA Lagoon Committee
May 2018
Presented by:
Steve Aiken
BS Civil Engineering – Wayne State Univ.
20 years in Design, O&M Assistance and Commissioning
Michigan Class A Wastewater Operator
20 years in Plant Operation, Maintenance and Supervision
Steve Aiken
Regional Sales Manager – Duperon Corp
7 years in Sales
Agenda: 1. General overview of different screening technology
2. Primer on Hydraulics
3. Wrap Up and Final Questions
Screening Overview
BackgroundManual screens or
comminutors used
to be the only way
to remove debris
from the influent
Different Screening
Technologies use different
types of bars, plates or screens
Bars Come In All Different
Shapes
Perforated Plate
Wedge Wire Screen
Different Types of Technology
Step Screen
Band Screen
Drum Screen
Climber
Helical Screw
Multi Rake
FlexRake – Sentinel FSP
Technology
Step / Stair
Screen
DEFINED: Utilizes individual
screening elements mounted
vertically which travels up from
the channel floor – similar
operation to an up escalator
STEP SCREEN Advantages
1. Can clean channels with smaller openings
(channel depth)
3. Able to remove non-bulky debris—excellent as
secondary screen for smaller opening
Technology Step Screen
Technology
Band Screen
Screens that move
around tracks or
sprockets that utilize
woven wire mesh or
perforated plate, either
in a continuous belt or
interlocking panels
Technology Band Screen
BAND SCREEN Advantages
1. Ideal for vertical applications
2. Can clean channels with smaller openings
(channel depth)
3. Able to remove non-bulky debris—excellent as
secondary screen for 1mm or 2mm
Technology Band Screen
DRUM SCREEN INTERNAL Advantages
1. Exceptionally fine screening available
2. No carryover
3. Available in-channel and above grade configurations
4. Common technology for membrane protection
Technology Drum Screen - internal
Technology
Drum Screen
- external
Technology -
Climber or Reciprocating RakeClimber arm that operates along a track with a chain to drive the cycle arm
CLIMER RAKE
Advantages
1. No trapped sprockets/tracks or wear in the
channel
2. Cleaning/raking mechanism does not remain in
the channel
3. Cleans coarse screens
Technology Helical Screw
DEFINED:
Cylindrical
screening basket in
the channel, solids
conveyed via helical
screw or augers
with brushes
HELICAL SCREW
Advantages1. Have some washing and light compaction all in
one unit – low capital cost
2. Ideal for low flow situations (up to 5 mgd) and
small channels
3. Completely contained process
Technology
Multi Rake
Flex Rake
Bottom Sprocket
Cantenary Screen
CHAIN/SPROCKET - Advantages
1. Trapped travel of flights/chain operates in back
current
2. Trapped travel—operates in side currents
3. Torque overload protection/reverse shuts unit
down if unable to clear debris
4. Easy-to-understand technology
Different Types of Technology
Step Screen
Band Screen
Drum Screen
Climber or Reciprocating Rake
Helical Screw or Basket
Multi Rake
AWWA
Hydraulics
for
Operators
Continuity Equation
Q = AVFlow (Q) = Cross Sectional Area (A) x Velocity (V)
Continuity Equation
Q = (W x D) * V
Aver Max
Bar Opening (regression) (regression)
(in.) (f^3/MG) (f^3/MG)
0.125 15.4 32.3
0.25 12.3 24.9
0.375 9.8 19.1
0.5 7.8 14.5
0.625 6.2 11.0
0.75 4.9 8.3
1 3.1 4.9
1.25 2.1 3.1
1.5 1.4 2.3
1.75 1.0 1.8
2 0.8 1.5
2.25 0.6 1.2
2.5 0.4 0.9
2.75 0.3 0.8
3 0.3 0.7
3.25 0.3 0.6
3.5 0.2 0.4
As Slot Opening Decreases,
Debris Removal Increases
Headloss Testing
Headloss vs. Approach Velocity
• Measured
• Calculated
Test Channel
Storage
Tank
Slope Adjustment
Pump
Headloss Testing
Open Channel Flow Equations
Bernoulli – 1740’s
Darcy-Weisbach - 1845
Manning - 1870
Hazen-Williams – 1920’s
Kirschmer – 1920’s
Commonly Used Equations in Open
Channel Flow
Bernoulli
Kirschmer HL = β (w/b)1.33 hv sin θ
HL = (V2-ν2)
C(2g)
ANY FINAL QUESTIONS?
Steve Aiken
Duperon Corporation
(O) 989-401-7710
(F) 989-754-2175
(M) 989 556-5265
1200 Leon Scott Court
Saginaw, MI 48601