lagoon seminar 2021 the importance of
TRANSCRIPT
• Michigan Class A Wastewater Operator
20 years in Plant Operation, Maintenance and Supervision
• BS Civil Engineering – Wayne State University
20 years in Design, O&M Assistance and Commissioning
• Regional Sales Manager – Duperon Corporation
10 years in Sales
STEVE AIKEN
AGENDA:
• Background
• General overview of different screening technology
• Step Screen
• Band Screen
• Climber
• Drum Screen
• Helical Screw
• Multi Rake
• Why Now at Lagoons
• Primer on Hydraulics
• Design and Operational Consideration
• Wrap Up and Final Questions
BACKGROUND
• Manual screens or comminutors used to be the only way to remove debris from the influent
• Lagoons typically didn't have screens as it was felt that the paper waste would biologically degrade over time
• Lagoons were considered low maintenance low capital investment that met the needs of a small community
GENERAL OVERVIEW OF
SCREENING TECHNOLOGIES
• Step Screen
• Band Screen
• Climber
• Drum Screen
• Internally or Externally Fed
• Helical Screw
• Multi Rake
• Fixed Sprocket, Link Driven, Cantenary
GENERAL OVERVIEW OF
SCREENING TECHNOLOGIES
• Step Screen
• Band Screen
• Climber
• Drum Screen
• Internally or Externally Fed
• Helical Screw
• Multi Rake
• Fixed Sprocket, Link Driven, Cantenary
STEP SCREEN
TECHNOLOGY
• Utilizes individual screening elements mounted vertically which travels up from the channel floor –similar operation to an up escalator
Advantages:
• Can clean channels with smaller openings (channel depth)
• Able to remove non-bulky debris—excellent as secondary screen for smaller opening
BAND SCREEN
TECHNOLOGY
• Screens that move around tracks
or sprockets that utilize woven wire
mesh or perforated plate, either in
a continuous belt or interlocking
panels.
Advantages
• Ideal for vertical applications
• Can clean channels with
smaller openings (channel
depth)
• Able to remove non-bulky
debris—excellent as secondary
screen for 2mm or 3mm
CLIMBER OR RECIPROCATING RAKE TECHNOLOGY
• Climber arm that operates along a track
with a chain to drive the cycle arm.
Advantages
• No trapped sprockets/tracks or wear in the channel
• Cleaning/raking mechanism does not remain in the channel
• Cleans coarse screens
Advantages
• Exceptionally fine screening available
• No carryover
• Available in-channel and above grade configurations
• Common technology for membrane protection
INTERNAL DRUM SCREENTECHNOLOGY
HELICAL SCREW TECHNOLOGY
• Cylindrical screening basket in
the channel, solids conveyed
via helical screw or augers with
brushes
Advantages
• Have some washing and light compaction all in one unit – low capital cost
• Ideal for low flow situations (up to 5 mgd) and small channels
• Completely contained process
CHAIN/SPROCKET
Advantages
• Trapped travel of flights/chain operates in back current
• Trapped travel—operates inside currents
• Torque overload protection/reverse shuts unit down if unable to clear debris
• Easy-to-understand technology
LINK DRIVEN
Advantages
• No confined space
• Minimal Maintenance requirements (only needs housekeeping)
• Jam evasion technology
• Easy-to-understand technology
TECHNOLOGY REVIEW
• Step Screen
• Band Screen
• Drum Screen
• Climber or Reciprocating Rake
• Helical Screw or Basket
• Multi Rake
OPEN CHANNEL FLOW EQUATIONS
• Bernoulli – 1740’s
• Darcy-Weisbach - 1845
• Manning - 1870
• Hazen-Williams – 1920’s
• Kirschmer – 1920’s
BARSCREEN CHANNEL HYDRAULICS
Kirschmer and Bernoulli ignore countless immeasurable, insignificant (?),
factors that would affect flow;
• Turbulence
• Water temp
• Constituents
• Viscosity
• Streamlines (speed variations)
• Walls of the channel
• Shape of the approach in the channel
• etc.
CONSIDERATIONS
• Opening size
• Bar Shape Factor
• Blinding
• Time to blind
• Channel Depth
• Freeboard
• Debris Removal or Carry Over
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
OPENING SIZEAs Slot Opening Decreases, Debris Removal
Increases
WEF paper: HYDRAULIC SIMILARITY OF HEADLOSS PREDICTIONS DERIVED USING COMMONLY USED METHODS VERSUS ACTUAL RESULTS AS IT
RELATES TO WASTEWATER SCREEN ELEMENTS
BAR SHAPE FACTOR
STEVE AIKEN
Duperon Corporation
(O) 989-401-7110
(F) 989-754-2175
(M) 989 996-5265
1200 Leon Scott Court
Saginaw, MI 48601