lagoon seminar 2021 the importance of

LAGOON SEMINAR 2021

Presented by: Steve Aiken

THE IMPORTANCE OF SCREENING TECHNOLOGY AT LAGOONS

• 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

SHAPES OF SCREENING ELEMENTS

STEP SCREEN

TECHNOLOGY

STEP SCREEN

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

INTERNAL DRUM SCREEN

TECHNOLOGY

Advantages

• Exceptionally fine screening available

• No carryover

• Available in-channel and above grade configurations

• Common technology for membrane protection

INTERNAL DRUM SCREENTECHNOLOGY

INTERNAL DRUM SCREEN

EXTERNALLY FED DRUM SCREEN

TECHNOLOGY

EXTERNALLY FED DRUM SCREEN

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

HELICAL SCREW

MULTI RAKETECHNOLOGY

FLEXRAKE

BOTTOM SPROCKET

CANTENARY SCREEN

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

AWWA HYDRAULICS FOR OPERATORS

CONTINUITY EQUATION

Q = AV

Flow (Q) = Cross Sectional Area (A) x Velocity (V)

Q = (W x D)

* V

CONTINUITY EQUATION

OPEN CHANNEL FLOW EQUATIONS

• Bernoulli – 1740’s

• Darcy-Weisbach - 1845

• Manning - 1870

• Hazen-Williams – 1920’s

• Kirschmer – 1920’s

HEADLOSS TESTING

Headloss vs. Approach Velocity

• Measured

• Calculated

Test Channel

Storage

Tank

Slope Adjustment

Pump

COMMONLY USED EQUATIONS

Bernoul

li

HL = β (w/b)1.33 hvsin θ

HL = (V2-

ν2)

C(2g)

Kirschme

r

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

BARSCREEN & RELATED TERMS

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

• Blinding

• Time to blind

CONSIDERATIONS

• Channel Depth

• Freeboard

• Debris Removal

CONSIDERATIONS

BARSCREEN & RELATED TERMS

ANY FINAL QUESTIONS?

STEVE AIKEN

Duperon Corporation

(O) 989-401-7110

(F) 989-754-2175

(M) 989 996-5265

1200 Leon Scott Court

Saginaw, MI 48601

[email protected]

lagoon seminar 2021 the importance of

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