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Wastewater Treatment
Techniques for pumping
sludge
Paul A. Nelsen
ITT Flygt Corporation
Marketing & Business Development
Manager
paul.nelsen@itt.com

Choosing the “right” pump…
….is like choosing the right golf club
at the Augusta National

…is like selecting the correct golf
club to match the conditions!
•Transfer (Driver)
•Metering (Putter)

Pumping Sludge
• Properties or the rheology of sludge
• What type of pump do I use?
• Advantages & Disadvantages
• Progressing Cavity
• Rotary Lobe
• Special Centrifugal
• Practical examples of sludge pumping

What’s your application?
− Return Activated
− Waste Activated
− Primary
− Supernatant
− Scum
− Digester feed
− Imported
− Centrifuge feed
− Belt press feed

Sludge video #1

Sludge video #2

Sludge video #3

Sludge video #4

To select a pump, you must know
the following properties:
1. Performance
a. Flow rate
b. Discharge Pressure
c. Suction Pressure (NPSHa)
2. % Dry Solids
3. Solid size
4. Abrasiveness
5. Do you need to Transfer & Meter Sludge?

Viscosity
• Viscosity, property of a fluid that tends to prevent it from
flowing when subjected to an applied force. The tenacity
with which a moving layer of fluid drags adjacent layers of
fluid.
Viscosity is the fluid property responsible for friction.

Viscosity as a function of shear rate
Viscosity is the property of a fluid that prevents it from flowing when
subjected to an applied force.
The tenacity with which a moving layer of fluid drags adjacent layers of fluid

NEWTONIAN
• Viscosity decreases
with the rate of shear.
Non NEWTONIAN
“thixotropic”
NON NEWTONIAN
“dilatant”
• Viscosity increases with
the rate of shear.

Measuring viscosity
Viscosity testing using both a Searle & Hache viscometer

Municipal wastewater sludge
• Municipal wastewater sludge is a Non-Newtonian Fluid.
• Sludge can start out at 300,000 cps and with the addition
of shear can come down to less then 300 cps.
• A centrifugal pump can not pump a viscosity >350 cps
and a sludge density of >6-8 percent.
Beware: water treatment sludge uses ALUM which is dilatant or
shear thickening.

Why do we
need to know
the type of
sludge?

What is the Rheology of the
sludge?
Things we need to know…
DS content?
Are there flocculants/polymers?

We hired a
team of
scientists
and
technicians
to perform
field tests
The test rig consisted of a tank, a dry-mounted pump N-
3127HT and a 4 inch flow loop with a flow meter, two pressure
transmitters and a control valve.

Laboratory & Field test results
• Pump derating:
• Performance curve:
- 1% per % DS (H)
• Power requirement:
Head - [m]
20
15
10
5
1 - 8 %
1 – 8 %
+ 1% per % DS
0
0 50 100 150 200 0
Flow - [m³/h]
5
4
3
2
1
Power - [kW]

Pipe dimension 1%
DS
4”
6”
8”
We charted the results
0.01 1)
1) 44 gpm 2) 132 gpm
0.01 2)
2%
DS
3%
DS
4%
DS
5%
DS
6%
DS
7%
DS
0.0. 0.02 0.05 0.1 0.15 0.25 0.35
0.01 0.01 0.01 0.02 0.04 0.07 0.11 0.17
0.01 0.01 0.01 0.01 0.02 0.04 0.06 0.09
8%
DS
0.01 0.04 0.08 0.15 0.25 0.38 0.54
0.01 0.01 0.01 0.03 0.06 0.11 0.17 0.24
0.01 0.01 0.01 0.02 0.03 0.06 0.1 0.14
Pressure loss estimation (ft/ft pipeline)

Things we learned:
• When designing system
• for DS>4% start-up condition must be considered (Δp>t x 4L/d)
• DS change of 2.5% → 4.5%, yield stress increases by factor of 5
• DS change of 2.5% → 8.5%, yield stress increases by factor of 30
Definition: Yield point, is defined in materials science as the stress at
which a material begins to plastically deform.

“TR185”
and
“Frost”

• Hydraulic gradient
• Pressure gradient
dP
dl
i
TR 185
2
V
g D
2
2
V
D
f
2
f
where,
i= hydraulic gradient (m/m)
V= average velocity (m/s)
g= gravity acc. (m/s 2 )
D= pipe diam. (m)
ρ= density (kg/m 3 )
f= Fanning friction factor
dP/dl= pressure gradient

TR 185
Reynolds number
R
Flow parameters:
V
D 8 V
e L
D
L – laminar viscosity (Nsn/m2)
n – power law index
( 1n
)
where,
ρ= density (kg/m 3 )
V= av. velocity (m/s)
D= diameter (m)
L= laminar viscosity
(Ns n /m 2 )
n= power law index

TR 185
h
where,
2
V
F
K
2
g
K= point loss factor
Fittings-loss factor
1000
Empirical relation between fitting-loss factor and
100
10
1
0,1
Reynolds number
F
1
1 10 100 1000 10000 100000
Reynolds number
2000
Re

Pump de-rating
• Performance curve: -
1% per % DS (H)
• Power requirement: +
1% per % DS (kW)
Head - [m]
20
15
10
5
1 - 8 %
1 – 8 %
0
0 50 100 150 200 0
Flow - [m³/h]
5
4
3
2
1
Power - [kW]

Flygt’s Sludge Module within FLYPS.
Flyps pump selection program to derate
pump curves.
Also, FLYPS can help you evaluate the
added losses experienced through
pipe work and fittings when pumping
sludge, as well as correct the motor
power data.

Enough about the fluids!
Let’s talk pumps!!!

Types of pumps used for “Thickened
sludge”
Diaphragm
Progressing
Cavity
Pumping
sludge
Rotary
Lobe
Special
Centrifugal

WEAR & TEAR!!!!!!!!!!!!!

What’s really important to WWTP?
• Reducing Operations Budget
• Increase reliability (solve clogging issues)
• Increase resistance to wear
• Reduce Energy Costs
• Flood-proof Protection
(i.e. recent floods in Nashville & Atlanta)

Positive displacement pumps are..
• Those in which energy is imparted to the liquid in a fixed
displacement volume.
Dynamic pumps are…
Dynamic pumps impart energy to the liquid by means of
an impeller or propeller.
This force is converted to pressure as the fluid is pushed
against the pump casing.

PD versus Centrifugal pumps
• Positive displacement or “PD” pumps
PD pumps are good metering devices.
PD pumps self-prime themselves.
• will supply as much pressure as needed until
the rated motor horsepower is exceeded.
• Centrifugal pumps
Centrifugal pumps do not meter.
Centrifugal pumps will not self-prime
• Need flooded suction
Flow rate will change as head pressure changes
(variations in suction or discharge pressure will
change flow rate).

Why use a Centrifugal pump?
• Low initial cost (< $$$’s)
• Lower cost of operation (< $$$’s)
• Less maintenance
• Easy maintenance
• Less energy consumption
• Reliable Operation
• Less chance of clogging
• More durable materials
• Less components to break
• No gear box required

Progressing Cavity Pumps

Manufacturers of “PC” pumps
• Moyno
• Monoflo (Mono)
• Netzsch
• Allweiler
• Seepex
• Tarby

Progressive Cavity Pumps
A single helix rotor turning in a double helix stator creating a
progressive cavity as the rotor turns

Advantages
•Pressures to 400 psig
•Pulls suction to 28 in-Hg V
•Metered flow
•Low shear
Disadvantages
•Will not run dry
•High starting torque
•Must run 180 rpm or less
•Requires a macerator
•Costly repairs & difficult to rebuild in place
•Liquid wants to be 200-300 cps viscosity or greater
Progressing Cavity
•Wears 3-4 times faster than a centrifugal pump in hard iron
•Typical WWTP application exposes mechanical seal to full discharge pressure

Failure points…

Rotary Lobe Pumps

Manufacturer’s of Rotary Lobe pumps…
•Vogelsang
•Boerger
•LobePro
•Alfa Laval
•Swaby Lobeline
•Netzsch

ROTARY LOBE Advantages
•Metered flow rate
•Pressures to 90 psig (really 40-50 psig)
•Runs dry for 5-10 minutes
•Compact
•Low shear pumping
•Low pulsations with screw rotor design
•Runs in either direction
Disadvantages
•High maintenance (3-4 times Npump)
•Expensive initial & repair costs
•High wear due to slip
•Not rag friendly, requires a macerator
•Requires gearbox running 180 rpm or less
•High starting torque

Failures…

FLYGT A-C Series
NS Non-clog Pumps

NON-CLOG PRODUCT
FEATURES
Tangential Discharge for ease of
Solid passing Capability. Discharge
Nozzle can be rotated to suit any one
of 8 discharge positions
Packing, Single , Double
Mechanical seal, or
Dynamic seal available
Back pull-out design eliminates
need to remove casing from piping
Horizontal and vertical mounting
arrangements available
Handhole or Clean-out port is standard on
casing (and suction nozzle when applicable)
Standard Gauge Connections
Standard 2-vane impellers.
Available in either CW or
CCW rotation
Close tolerance stainless steel
impeller wear ring and suction
cover wear plate combination to
provide high and easily renewable
operating efficiencies
Tapered shaft/impeller fit (will
not loosen and hence reduces
vibration)
Standard Casing Drain & Vent

Non-clog impeller

Non-clog Pumps

•Advantages
Centrifugal Recessed Impeller
•Slurry design
•Handles large solids
•Minimal contact with solids
•Quiet operation
•Semi-clog resistant
•Disadvantages
•Does not meter flow
•Very low efficiency
•Requires special materials

RECESSED IMPELLER or Vortex
Spherical
Solid Size…

Recessed
Impeller
Grit Pumps

Centrifugal Screw Pump
Vertical leading edge which grabs rags
Advantages
•Solids handling
•Smooth flow
•Efficient to 80 percent
Disadvantages
•High initial cost
•Requires special materials
•Not a metering pump
•Tough to manufacture & balance
•Clogs at vertical leading edge
•Very long shaft overhang causing shaft
deflection
•premature bearing failure and
contact/interference to suction cover

Flygt N-Pump
•Advantages
•Solids Handling to 6-8 percent
•Clog resistant (Back swept leading edge)
•Cutter grove in volute “Insert ring” tears
solids
•Efficient operation
•Small, compact design
•Center-line discharge
•Disadvantages
• will not become air bound
•Does not meter (without FMC & VFD)
•Requires special materials
•Must be installed in the NZ configuration

WEAR: Cast iron impeller & insert ring

Advantages
Centrifugal CHOPPERS
• Heavy duty design
• Chops solids to small sizes
• Reliable operation until cut bar wears
Disadvantages
• Inefficient design
• High wear on cutter bar
• Clogs with minimal wear on cutter bar

FLYGT “Chopper” pumps
Advantages
• Heavy duty design
• Chops solids to small sizes
• Modular design
• Hard iron 25% Cr
• Guide pin
Cast Iron Impeller
Disadvantages
• Efficiency drops 15-20 percent over Npump
• Does not meter
• Requires special materials
Cast Iron Insert ring Hard-Iron Insert ring
Hard-Iron Chopper ring
Pump housing
Hard-Iron Impeller

Pump selection recommendations
Flow (gpm)
30
Primary
sludge
removal
RAS
WAS
Digested
sludge
N-pump, first choice
PC-pump, first choice
Thickened
sludge
Dewatered
sludge
PC-pump,
first choice
Global market (MUSD/Year)

Let’s talk clogging…

Must handle rags!

…or these modern day clogging headaches

What is the efficiency of a clogged pump?
•NP 3127 impeller 488
•Pump after 5 years of operation
•Never Clogged !

JEA – Jacksonville, Florida

Practical examples of pumping
sludge
•Oak Ridge, TN.
•Tybee Island, GA.

Oak Ridge, TN

Tybee Island, GA
Flygt replaced two 25 hp PC pumps with two 5hp
NT3102-465 pump!
Application = RAS

Summary
If it flows, use gravity.
If gravity does not work… use a centrifugal pump.
Lower Life Cycle Cost (LCC)
A centrifugal pump can not pump a viscosity
>350 cps and a sludge density of >8 percent.
Keep pipe work simple with short suction line
constant diameter
no bends or elbows

Paul A. Nelsen
Marketing & Business Development Mgr
FLYGT Products
paul.nelsen@itt.com

• What’s really important to this market?
• Selling against competing technologies:
• Sludge Pumps
• Reciprocating
• Progressing Cavity
• Rotary Lobe
• Influent Pumps
• Archimedes Screw Pumps
• Miscellaneous
• Cutter pumps
Agenda
• Presenting ITT’s Sludge Handbook

What’s really important to this customer?
• Reducing his Operations Budget
• Increase reliability (solve clogging issues)
• Increase resistance to wear (3-4 times the life)
• Reduce Energy Costs
• Flood-proof Protection
(i.e. recent floods in Nashville & Atlanta)

But to properly select a pump,
you must know the following properties:
Performance expectations
a. Flow rate
b. Discharge Pressure
c. Suction Pressure (NPSHa)
d. % Dry Solids
e. Does customer need to Transfer & Meter Sludge?

It’s like choosing the right golf club….
•Transfer (Driver)
•Metering (Putter)

Types of pumps used for sludge
Plunger,
Double Disc,
&
Diaphragm
Progressing
Cavity
Pumping
sludge
Rotary
Lobe
Centrifugal

Positive displacement pumps are..
• Those in which energy is imparted to the liquid in a fixed
displacement volume.
• Such as a casing or a cylinder, by the rotary motion of gears,
screws or vanes, or by reciprocating pistons or plungers.
Dynamic pumps are…
Dynamic pumps impart energy to the liquid by means of
an impeller or propeller.
This force is converted to pressure as the fluid is pushed
against the pump casing.

PD vs. Centrifugal pumps
• Positive displacement or “PD” pumps
PD pumps are good metering devices.
PD pumps self-prime themselves.
PD pumps will supply as much pressure as needed until
the rated motor horsepower is exceeded
• Centrifugal pumps
× Centrifugal pumps do not meter.
× Centrifugal pumps will not self-prime
× Need flooded suction
× Flow rate will change as head pressure changes
(variations in suction or discharge pressure will change flow rate)

Why use an Npump?
• Lower initial cost (< $$$’s)
• Lower cost of operation (< $$$’s)
• Less maintenance
• Easy maintenance
• Less energy consumption
• No Macerator required
• Reliable Operation
• Eliminates potential for clogging
• More durable materials
• Less components to break
• No gear box required

Competing Technologies

Plunger Pumps

How does a Plunger pump work?

Manufacturers of Plunger pumps
•WASTECORP.
•Komline-Sanderson
•Carter Pumps Inc.

Easy to Maintain????

Here’s a “typical” parts list…

Advantages
• Positive displacement
• Self priming
• Meters flow
• Flow rate is not system head
dependent
• Flow rate is not sludge
concentration dependent
• Easy clean out capability
• Low cost of maintenance???
Plunger Pumps
Disadvantages
• High Capital Cost
• High Maintenance
• Lots &Lots of Parts
• Packing Leaks
• Must lubricate Babbit that
drives plungers
(2-3 drops/min = 1 quart/day)
• Very Messy

Existing TWAS Pump

New TWAS Pump
• NT3102 – 5hp was installed in 2002.
• Empties tank in less than a third of the time it took the previous pump.

Double Disc & Diaphragm Pumps

Manufacturers of Disk or Diaphragm pumps
• Penn Valley
• SSP Alfa Laval
• Dorr Oliver ODS
• Carter Pumps
• Gorman-Rupp

Operating Principle
The Double Disc is based on a “Free Diaphragm”
technology, the pump utilizes a unique principle of
operation where the discs perform the duties of both
diaphragm and valve.
Suction Cycle Discharge Cycle

Operation sequence of Diaphragm pumps

Features & Benefits
Repair-in-Place design w/ hinged housings
Only 5 wetted components
Self-priming with high suction lifts
Seal-less design, no packing or mechanical seals
No seal water required
Runs dry without damage
No check valves, no fouling problems
Handles up to 3/4” solids
Two (2) year warranty

Do It Yourself with genuine Double Disc parts.

Double Disc & Diaphragm Pumps
Advantages
• Simple, rugged design
• Easy maintenance
Disadvantages
• High purchase price
• Frequent maintenance
• Flexure life = 400,000 cycles
• large pulsations w/o dampeners
• Do not handle bottle caps

Midland, Texas – Diaphragm pump
• Eight Gorman-Rupp pumps being powered by six – 7.5 to 10hp compressors
• Efficiency goes from 100% theoretical to 20-22% because of high cost for making air.

Progressing Cavity Pumps

Manufacturers of “PC” pumps
• Moyno
• Monoflo (Mono)
• Netzsch
• Allweiler
• Seepex
• Tarby

Progressive Cavity Pumps
A single helix rotor turning in a double helix stator creating a
progressive cavity as the rotor turns

Advantages
•Pressures to 400 psig
•Pulls suction to 28 in-Hg V
•Metered flow
•Low shear
Disadvantages
•Will not run dry
•High starting torque
•Must run 180 rpm or less
•Requires a macerator
•Costly repairs & difficult to rebuild in place
•Liquid wants to be 200-300 cps viscosity or greater
Progressing Cavity
•Wears 3-4 times faster than a centrifugal pump in hard iron
•Typical WWTP application exposes mechanical seal to full discharge pressure

Failure points…

6,000
5,000
4,000
3,000
2,000
1,000
0
Primary Sludge
• 3-5% Dry Solids
• Transfer 360 ft, 30ft Static
• Pumps Start with Flooded Suction
• Then Run on Suction Lift
• $4000 Savings – per pump/yr.
Capex Energy Spares Labor Total
P C Pump
N Pump
Saving

Digester Recirculation
• Replaced existing “PC” pumps
• Pumps run 24/7 with minimal spare parts usage
• 8-9 degF rise in digester temperature (82 to 91 degF)
(Less energy input into heat exchanger)
• Reduced cost of ownership

Digester Recirculation
• Digester Recirculation Sludge ~ 5% DS
• Very Raggy, existing pumps block daily
• Expensive to Repair ~ $9500
• Digester Temp. 9 o F Higher
• Three Pumps Installed in Total
• Process down-time eliminated!

Replaced 25 hp PC pumps with 5hp Npumps
•Trial Pump for RAS Application
(immediately purchased a 2 nd pump)
•Repaired PC pumps 2-3 times/yr.
•3 yrs - never touched their Npump

Rotary Lobe Pumps

Manufacturer’s of Rotary Lobe pumps…
•Vogelsang
•Boerger
•LobePro
•Alfa Laval
•Swaby Lobeline
•Netzsch

ROTARY LOBE Advantages
•Metered flow rate
•Pressures to 90 psig (really 40-50 psig)
•Runs dry for 5-10 minutes
•Compact
•Low shear pumping
•Low pulsations with screw rotor design
•Runs in either direction
Disadvantages
•High maintenance (3-4 times Npump)
•Expensive initial & repair costs
•High wear due to slip
•Not rag friendly, requires a macerator
•Requires gearbox running 180 rpm or less
•High starting torque

Failures…

Replace RLP with Npumps
• Customer was spending $8k
per month to repair the Boerger
pumps (nine total)
Boerger pump
Replaced RLP with Npump on 6 month
trial and customer immediately
purchased a second pump (before trial
was completed)
Flygt N-pump

Economics (Life Cycle Costs)
Life Cycle Cost
Initial Purchase
Planned maintenance
*Cost of rebuild
10 year cost
PC
$21,000
$0
$7,000
$42,000
Lobe
$19,000
$0
$6,000
$37,000
DISC
$23,000
$0
$2,000
$33,000
* Considers three rebuilds for both PC & RL pumps, 5 rebuilds for DISC and no
rebuilds for Npump
(N pump must have Hard iron impeller & Insert Ring)
N pump
$11,000
$4,000
$0
$15,000

Screw Conveyor Pumps

Why Use a Screw Pump?
The Archimedes Screw Pump
• Efficient in handling large volumes of liquid at relatively low lifts.
• Ability to handle variable capacity with a simple constant speed drive.
• Operates at or above 70% efficiency for 2/3 of its operating capacity.
• No increase in pumping head caused by deep influent as required for centrifugal pumps.
• Less head required because there are no friction losses created by pipe, valves, and fittings.
• Non-clog

Screw Conveyor Pump Manufacturers
• Siemens (US Filter)
• Lakeside Equipment Company
• Spaans Babcock
• BioSec Enviro
• Martin Sprocket & Gear, Inc.
• Torqueflow Sydex
• Schreiber LLC.
• Arlat Technology - A Div. of Price Schonstrom Inc.
• Landustrie Sneek BV (Landy Screw Pumps)
• EPIC International
• Ritz-Atro GmbH
• SPECO Division of WAM S.p.A.

Advantages
• Rugged, Heavy-duty
• Non-Clogging design
• Lower cost concrete trough
• Low speed
• Low noise
Screw Conveyor Pumps
Disadvantages
• Huge Capital cost
• Purchase price (3-5 x’s)
• Installation cost (3-5 x’s)
• Requires a lot of space
• Huge grease lubrication costs
(Upwards of $70,000/ yr.)
• 3-4 days to remove & service
• Highly inefficient when flighting to
concrete trough wears

Screw
Conveyor
Pumps

Screw Pump Replacement
Delta Township, MI

Screw Pump Replacement
O’Fallon, MO

JCH replaced these 10 mgd @ 50 feet CPC Screw Pumps
•CP pump ran from 1992-2007 (15 years)
•N pumps have since replaced C pumps (1997-today)

Cutter Pumps
• Vaughan
• Landia
• Tsurumi
• Barnes
• BJM

Their Sales Pitch…

Competitor’s pump

Competitor’s pump

Weakness as perceived by the competition

Tsurumi selling points

Advantages
• Heavy duty design
• Cuts solids to small sizes
• Reliable operation
(until cut bar wears)
Disadvantages
• Inefficient
• Inferior cutter bar material
• Clogs with minimal wear
CHOPPER/ CUTTER

FLYGT “Chopper” pumps
Advantages
• Heavy duty design
• Chops solids to small sizes
• Modular design
• Superior Hard iron material
• Guide pin
Disadvantages
• Efficiency drops 15-20%
over Npump
• Does not meter
Cast Iron Impeller
Cast Iron Insert ring Hard-Iron Insert ring
Hard-Iron Chopper ring
Pump housing
Hard-Iron Impeller

Flygt N-Pump Advantages
•Solids Handling to 6-8 percent
•Clog resistant (Back swept leading edge)
•Cutter grove in volute “Insert ring” tears solids
•Efficient operation
•Small, compact design
•Center-line discharge
• will not become air bound
•Complete ownership for pump & motor
Disadvantages
•Does not meter
•Does not self-prime
•Not a “PD” pump

High chrome gives…
4 x life vs. cast iron
2 x life vs. hardened tool steel

Vaughan Chopper Replacement
• Requirement: Flygt Cutter had to Work on Vaughan RotoMix System
• Installed Since March 2010 w/ no sign of wear
• Higher Flow than Vaughan Unit (870 vs. 443 gpm)
• Indications of Better Mixing
• Surface Crust Appears to be Breaking

Npump replaces competitors Chopper
Lift station pump which clogged weekly due to worn cutter
bar was replaced with Npump and has not clogged since!
* City now has flood-proof protection!

MACERATORS

MACERATORS
These types of pumps require a Macerator:
•Piston Plunger
•Diaphragm
•Double Disc
•Progressing Cavity
•Rotary Lobe

…because they cannot handle rags!

…or these modern day clogging headaches

Npumps do not require a Macerator!
• No Muffin Monster!
• No Franklin Miller!
• No Seepex!
• No Vogelsang!
• No Boerger!
• No Allweiler!
• No Monoflo!

Summary: Rule of thumb
If it flows, use an Npump!
Lower Life Cycle Cost (LCC)
A centrifugal pump can not pump a viscosity
>350 cps and a sludge density of >6-8 percent.
Keep pipe work simple with short suction line
constant diameter
no bends or elbows
no constrictions

For ALL Treatment Plant Pump Activities…
Applications
− RAS, WAS, TWAS & Primary
− Scum pits
− Digester feed
− Imported
− Influent/ Final Effluent
Competing technologies
− Plunger
− Diaphragm
− Double Disc
− Progressing Cavity
− Rotary Lobe
Please call or Email me for help &
guidance:
Paul Nelsen
(203) 610-0853

To be released
soon!

THANK
YOU!
Paul A. Nelsen
Market Manager
Industrial & Treatment Plant Pumping
paul.nelsen@itt.com