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“Modern Collection System Solids-handling
Challenges / Energy Saving Advancements”
Bob Domkowski Municipal Business Development Manager / Engineering Consultant
Xylem, Inc., Water Solutions USA - Flygt
How many of you recognize this?
Pumps choked with
modern trash!
Modern day collection system headaches
Modern trash
Baby wipes
‘Swiffer’ wiping sheets
Plastics
Baby diaper liners
Toilet bowl cleaning pads and wands
Shop rags
‘Wettex’ spongy / cotton reinforced kitchen sheets
Dusting sheets
Hygiene products
Typical WWTP Diurnal Curve
Sewage flow pattern for a typical municipality
Treatm
ent
capacit
y (
mgd)
WE&T – August, 2008 Edition Portland Water District (PWD) – ‘Awareness campaign’
Pro
babili
ty
The reality of today’s wastewater: Probability of solids distribution
Solids Rags
100%
0%
Complications of ‘Modern Trash’
Concerns first raised at: Environment 1993 Conference…
“Flushability, Transportation and Decomposition of Non-woven Products”
- Authors related that:
- Non-woven flushable products may not be flushable
- 1994 Fed. legislation reduced flush volume to 1.6 gal.
- Laboratory and field studies predicted difficulties in
developing consumer products that met both:
- Regulations
- Consumer needs
INDA – ‘Flushability’ Investigation
Flushability project
Flushability Project… a 3-year project
• What is flushable?
• ‘Flushability’ has been left up to individual product manufacturers
• High risk:
- Non-woven products can harm both homeowners and municipal
collection systems
• Develop standardized test procedure for product manufacturers
• INDA external experts have worked to develop a test program
• Flygt is one such ‘external expert’ consultants
• Final guidance is expected within ~12-months
INDA - The Association of Non-woven Fabrics
Flushability – INDA Definition
INDA: For a product to be flushable it must:
1.) Clear toilets and properly maintained drainage pipe
systems under expected product usage conditions;
2.) Be compatible with existing wastewater conveyance,
treatment, reuse and disposal systems; and
3.) Become unrecognizable in a reasonable period of time
and be safe in the natural receiving environments.
Today’s reality: MWWCA Membership 2010 Collection System Operations Survey
87.5% experienced problems with “flushable’ products.
61.4% experienced >10 incidents with “flushable” items
84.4% clogging problems in small lift stations due to “flushables”
51.1% clogging problems in large lift stations due to “flushables”
59.6% Costs due to ‘flushables’ is up to $1,000 per incident
12.8% Costs due to ‘flushables’ of up to $2,000 per incident
88.9% Report that problems with “flushables” are increasing
Case Study: Town of Moraga, Costra County, CA
• Significant number of pump clog incidents per month
• 3” bar screen replaced with 1.5” bar screen
• Case study results:
- Increased frequency of bar screen cleaning
- Bar screen blinding by ‘pan-caking’ of brown towel sheets
- While reduced, pumps each still clogged 3-4 times /mo.
Town of Moraga, Costra County, CA Recorded wastewater trash distribution
Paper
Hygenic
Wipes
Other
Other
Hygenic
Wipes
Bar screen capture Pump clog components
54%
17%
13%
16%
70%
19%
11%
Case Study: Town of Moraga, Costra County, CA
Pump clogs mainly consisted of:
- Long, twisted, knotted, rope-like formations
- Strong non-woven materials
- Long fibrous products:
- Personal hygiene products
- Household cleaning wipes
- Personal wipes
Town of Moraga, Costra County, CA Typical pump clog sample
Pump clog debris
Decomposed debris clog
Pro
babili
ty
The reality of today’s wastewater: Probability of solids distribution
Solids Rags
100%
0%
On the Legislative Front
California – 2010 Rep. Jared Huffman drafts legislation requiring
manufacturers to follow INDA definition of ‘flushable’ and
require consistent packaging
Maine – 2011 Rep. Melissa Walsh submits a bill on behalf of MWWCA
addressing concern of the impact of products marked as
‘flushable’ that are not dispersing in wastewater systems.
Bill would prohibit the sale of ‘flushable’ products that do not
meet flushability standards
Modern wastewater: Wastewater pumping is a tough application!
Innovative technology in pump design
Q: How many of you believe that today, the most
effective solids-handling pump…
Is one that can pass a 3-inch diameter solid?
Innovative technology in pump design
For the sewage historians in the room…
Q: Where and when did the requirement for
wastewater impellers having a 3” throughlet
originate?
Solids-handling pumps – A history lesson
A: Mr. A. Baldwin Wood – 1915 • Assistant Superintendent, New Orleans S & WB
• “Father of the ‘non-clog’ wastewater pump” developed the
Wood “Trash Pump”
Typical 2-channel solids-handling impeller
Solids-handling pumps – A history lesson
• Wood theorized that a better wastewater pump
would result if an impeller had vanes with blunt
leading edges and large throughlets
• His intuitive specifications resulted:
- Minimum sized conveying line: 4-inch
- Minimum throughlet size: 3-inch
Today’s Collection Systems Challenge: Keeping sewage pumps operating
Innovative technology In solids-handling pump design
Semi-open, non-clog, multi-vane,
self-cleaning impeller with
horizontal back-swept vanes
Vane leading edges are wiped
clean at the interface of the relief-
groove during each rotation
Innovative technology
Self-cleaning, N-Hydraulics
providing sustained high
hydraulic efficiency
Innovative technology In solids-handling pump design
What Is Clogging Anyway?
Innovative technology In solids-handling pump design
These pumps are clogged!
Innovative technology In solids-handling pump design
What Is Clogging Anyway?
• Clogging is defined as “a partial or full blockage of the
pump resulting in from reduced to non-existent flow”.
• Most clogging instances result in limited flow reductions
( i.e. ) the pump will still deliver some flow, but not very
efficiently.
• A. Baldwin Wood’s ‘non-clog’ pump was developed to
minimize the risk of complete blockage.
Innovative technology
In solids-handling pump design
A dose of reality… • The ‘Pumping Station Design’ book by Dr. Robert L.
Sanks defines a non-clog pump as:
“… a centrifugal pump designed to pump liquids
containing suspended solids and stringy materials.
( Ed. Note: In spite of the name, they will
sometimes clog )”
Innovative technology In solids-handling pump design
Both laboratory tests and field installations
alike show that sewage pump clogging is
mainly due to:
1. Rags and stringy materials that get stuck on the
impeller vane edge or in the eye of the impeller.
2. Jamming of the impeller / wear ring interface.
3. Full plugging of the volute (Vortex pumps)
Innovative technology In solids-handling pump design
Laboratory pump clog test rig
Innovative technology
In solids-handling pump design
• 10” x 10” test objects were fed into each pump
- One at a time, at 15 sec. intervals.
• Test objects: 10 mil plastic strips, ‘Wettex’ dish cloths
and reinforced textile rags, 50 pcs of each.
• Tests were performed at flows of:
- 900 gpm and 1,250 gpm
• All test program pumps had 4” discharge
Laboratory test protocol developed...
Innovative technology In solids-handling pump design
Laboratory test objects
Innovative technology In solids-handling pump design
0
10
20
30
40
50
60
70
80
90
Closed 1-V 2-V Vortex Screw Open 1-V Chopper N-Hydraulics
Hydraulic efficiency in clean water
Hydraulic efficiency recorded during repeated clog tests
Pump efficiency comparison by impeller type
Innovative technology
In solids-handling pump design
• Impeller design is much more important than throughlet
size to prevent clogging.
• Impeller vane leading edge angle is very important.
• The maintaining of cleanliness of the leading edge of the
impeller vane(s) is of utmost importance.
Clog test conclusions
Wastewater pumping / energy consumption
Constant duty Typical lift sta. Self-cleaning type
Innovative technology In solids-handling pump design
Since 2000, more than 70,000 Flygt N-Pumps have been
sold and are successfully operating in the U.S. pumping raw,
unscreened sewage, wastewater and sludge.
N-Pump Performance Field
500-hp
3-hp
250 500 1,000 2,000 5,000 7,500 10,000
US gpm
10
25
50
100
200
300
The Adaptive Flygt® N-impeller
Small jumps take you to the highest level
The Adaptive Flygt® N-impeller
Back-swept
impeller vanes
Integral
guide pin
Relief
groove
Replaceable
volute insert
ring
The Flygt AdaptiveTM N-impeller
1.The N Technology
self-cleaning concept
2.The Adaptive functionality
N-Hydraulics chosen as
2011 WEF Innovative Technology
Award Winning Product
3.0-hp through 10-hp
Adaptive N-Impeller operation
Differential
pressure during
normal operation
Impeller can rise ~15mm (0.6”)
F F
Santa Fe, NM WWTP: N-3085
Clarifier scum pit
- Centrifugal pump clogged daily
- Chopper pump clogged several times weekly
- Adaptive-N has not clogged once since 11/21/08
Berkley Co., SC: P.S. #015
Existing submersible pumps clog frequently
- N-3102.160 / 5-hp installed 7-Jan, 2010… No clogs
- Original pump continues to clog
- Energy study by owner is now underway
Consortium for Energy Efficiency
Municipal water and wastewater systems
• Consumes 4% of all U.S. energy
• 52,000 water systems produce 51Bn gallons of water per day
• 16,320 wastewater treatment facilities treat 34.8Bn gallons per day
• Greatest energy consumer in water treatment: Pumps
• Greatest energy consumers in wastewater treatment are:
- 1. Blowers
- 2. Pumps
- 3. Sludge handling equipment
Industrial Programs
National Municipal Water and
Wastewater Facility Initiative
Energy savings: Typical life cycle cost for a pumping system (Source: EPA)
Downtime
Maintenance
InstallationPump
Energy
Operating
Environmental
25%
40%
10% 7%
5% 10%
3%
Potential energy savings: By motor hp and application (Source: WEF)
Pump savings
Motor upgrades
Air compressor savings
Other savings
Fan savings
Downsize savings
Rewind savings
1-5
HP
5-2
0 H
P
25-5
0 h
p
51-1
00 H
P
101-2
00 H
P
201-5
00 H
P
501-1
000 H
P
> 1
,000 H
P
Lumberton, TX – Municipal Utility District Recorded Energy Savings 2003 to 2010
Service area: 63 mi2 Population: 20,400
Budget saving project overviews
Rockport, TX • (2) 25-hp self priming pumps replaced by…
• (2) 10-hp Flygt N-pumps
• Results: - Monthly energy charges reduced by 40%
- Utility demand charges eliminated
- Pump run-time cut in half!
Vancouver, WA – Anderson P.S. • (4) 40-hp submersible pumps had frequent fouling and clogging
- 2-in thick pile of work orders for unclogging pumps over 2-years
• (4) Flygt N-3171 / 25hp pumps installed
- $20,000 first year savings: maintenance / energy charges
Recent energy saving project As seen in WWD Spring 2012 “Pump Source”
City of Andalusia, AL
• U.S. DOE Block Grant
- Alabama Dept. of Economics and Community Affairs
• Project specification:
- 25% energy savings guarantee the responsibility of the contractor
- Failure to achieve: Contractor reimburses $250,000 ADECE funding
- Central Lift Station
- (3) 85-hp and (2) 45-hp N-pumps installed
56.1% Energy savings recorded by engineer: Goodwyn, Mills & Caywood
- Riverside WWTP
- (3) 45-hp N-pumps installed
48.1% Energy savings recorded by engineer: Goodwyn, Mills & Caywood
Recent energy saving project As seen in P&S – March 2012
City of Waconia, MN
Duplex 70-hp pump station
Prior to 01/11 retrofit (10-month period)
18 daytime clogs
16 nighttime clogs (Out sourced)
$14,027 spent on pulling pumps
Average of $1,400 per month
Since January 2011installation…
NO Clogs experienced!
Average energy savings is 30%
Average maintenance savings is $21,000
Clean Water SRF –
20% Green Project Reserve Funds
Guidance for Determining Project Eligibility
3.2-2 Projects that achieve a 20% reduction in energy
consumption are categorically eligible for GPR4.
Retrofit projects should compare energy used by
the existing system or unit process5 to the proposed
project. The energy used by the existing system
should be based on name plate data when the
system was first installed.
EPA SRF Green Project Reserves
Guidance
Typical Worksheet
Bob Domkowski Municipal Business Development Manager / Engineering Consultant
Xylem, Inc., Water Solutions USA - Flygt
“Modern Collection System Solids-handling
Challenges / Energy Saving Advancements”