Post on 12-Apr-2018
DISINTEGRATION OF
FLUSHABLE WET WIPES IN
WASTEWATER SYSTEMS
Fatih KARADAGLI, Ph.D.
Associate Professor
Department of Environmental Engineering
Sakarya University, Turkey
ORGANIZATION
BACKGROUND AND RESEARCH PROBLEM
PHYSICAL CHARACTERIZATION OF WET WIPES
TRANSLATION OF RESULTS TO SEWER SYSTEMS
CONCLUSIONS AND FUTURE
PHYSICAL DISINTEGRATION
Theory, Mathematical Modeling, and Experimental Testing
Time
line
Team Collaborator Goal
2001-2003
Prof. Bruce E.
Rittmann and Fatih
Karadagli (Graduate
Student) of
Northwestern University
Dr. Drew C. McAvoy of
Environmental R&D
Departmant at Procter and
Gamble Co.
1- Theoretical and mathematical model
development for physical disintegration
2- Experimental testing with tampons
2004-2007 Prof. Bruce E.
Rittmann and Dr.
Fatih Karadagli
Dr. Drew C. McAvoy,
and John E. Richardson
of Blue Hill Hydraulics,
Inc.
1- 3-Dimensional flow modeling of the shake-
flask experimental system,
2- Estimation of flow velocity, kinetic energy,
and Reynold’s number of fluid motion in the
experimental system
2007-2011 Dr. Fatih Karadagli
and Mr. Beytullah
Eren
Meral Tirak and Besim
Kaplan of Georgia-
Pacific-Eczacibasi (Turkey)
Disintegration of toilet papers in wastewater
systems
2014- Dr. Fatih Karadagli,
Dr. Beytullah Eren
Prof. Bruce E. Rittmann,
Biodesign Institute at
Arizona State University
Disintegration of flushable wet wipes in
wastewater systems
Flushable Wet Wipes
Product variety
Baby cleansing
Toddler wipes
Patient wipes
Adult wipes
Feminine wipes
Facial cleansing
Product Structure or Composition
Cellulosic fibers (wood, tencel)
Cotton fiber
Latex fiber
Binding chemicals
Fragrances
Flushable Wet Wipes – North America
Flushable Wet Wipes - Europe
Adverse Effects In Sewer Networks
• Food waste – Fat, oil, and grease (FOG) FOG deposits
• Detergents, cleaning agents, personal care products
• Water flow characteristics – flow rate and velocity
• Pipe characteristics – slope, diameter, and pumping stations
• In streets – Sanitary sewer overflows
• Rainfall and surface debris, root penetration,
By courtesy of
Mr. Barry Orr,
Wastewater treatment
operations
City of London
Consequences and Problems
50,000 SSOs and 400,000 basement backups per year in the USA
Microbial & Chemical Threats : Chlorea, Giardasis, Chryptosporidiosis, and Hepatitis
Financial problems due to cloggings and equipment failures
Research Questions
How do wet wipes disintegrate?
Can we identify disintegration patterns?
Do sewer systems support transport and disintegration of wipes?
Environmental feedback to manufacturers
Consumer expectations vs. environmental impacts
Characterization of wet wipes
Physical disintegration
Translation of results to sewer systems
CHARACTERIZATION OF WET WIPES
SAMPLES OF FLUSHABLE WIPES FROM NORTH AMERICA
Product Category Brand Name Product Name Manufacturer /
Distributor
Baby Pampers Kandoo P&G
Baby Charmin Freshmates P&G
Adult Scott Scott Naturals Kimberly-Clark
Adult Cottonelle FreshCare Kimberly-Clark
Adult Cottonelle Ultra ComfortCare Kimberly-Clark
Adult Kirkland Signature Moist Flushable Wipes Costco
Adult GreatValue Flushable Wipes Walmart
Adult Equate Flushable Wipes Walmart
Feminine Equate Personal Cleansing Cloths Walmart
Patient Tucks Medicated Cooling Pads McNeil-PPS
Patient Equate Hemorrhodial Pads Walmart
Patient Preparation H Medicated Wipes Wyeth Consumer
Healthcare
Country Brand Name Product Name Manufacturer / Distributor
Austria Clever Feuchtes toilettenpapier Pantos Productions- und Vertriebsges
Austria Quality First Feuchtes toilettenpapier Albaad Deutschland GmbH
Austria Tempo Sanft & Pflegend SCA
Austria Hakle Clean Comfort Kimberly-Clark/Hakle
Austria Hakle Natütlich pflegend Kimberly-Clark/Hakle
Germany Favora Kamille Feuchtes toilettenpapier Albaad Deutschland GmbH
Germany Favora Sensitiv Feuchtes toilettenpapier Albaad Deutschland GmbH
Germany Hakle Clean Comfort Kimberly-Clark/Hakle
Germany Hakle-Cottonelle Pure Sensitive Kimberly-Clark/Hakle
Hungary Alouette Kamille Feuchtes toilettenpapier Dirk Rossmann Co.
Holland Albert Heijn Voching ToiletPapier Albert Heijn Co.
Italy Fria Carta Igienica Umidificata Diva International S.r.i, Spello (PG)
Finland Lambi Kosteuspyyhe Metsa Tissue Oyj
France Nivea Baby Toddies Beiersdorf
France Pampers Kandoo P&G
England Andrex Washlets To Go Kimberly-Clark
England Sainsbury’s Flushable Toilet Tissue Wipes Sainsbury’s Supermarket Ltd
England Tesco Moist Toilet Tissue Tesco Stores Ltd
SAMPLES OF FLUSHABLE WIPES FROM EUROPEAN UNION
SAMPLES OF FLUSHABLE WIPES FROM FAR EAST
(JAPAN, CHINA, AND SOUTH KOREA)
Product Category Brand Name Product Name Manufacturer /
Distributor
Adult Haso Adult sheets Haso Ltd.
Baby Haso Skin-care baby wipe Haso Ltd.
Adult Pigeon Habisasu Pigeon Ltd.
Baby wipes Pigeon Baby wipes Pigeon Ltd
Physical Properties Used for Categorization
Sheet mass (g)
Sheet surface area (mm2)
Thickness of a sheet
Sheet volume (mm3)
Basis weight (g/m2): Weight per surface area = Sheet mass / sheet surface area
Specific volume (dm3/kg): Volume per unit mass = Sheet volume/sheet mass
Thickness Measurements
I.D. Sheet Mass
(mg/sheet)
Surface Area
(Length x Width)
(mm2)
Basis Weight
(g/m2)
Sheet
Thickness
(µm)
Sheet
Volume
(mm3)
Specific
Volume
(dm3/kg)
Additional
Info.
Range 1830 - 5807 4475 - 27440 170-616 227 - 611 2099 - 8206 1.0 – 1.6
Average 4513 19982 265 351 6385 1.4
NA-SN-4 4889 23680 206 305 7218 1.5 Adult – SFT
NA-SN-6 4571 23607 194 316 7448 1.6 Adult
Physical Properties of Flushable Wet Wipes from North America (as received)
I.D. Sheet Mass
(mg/sheet)
Surface Area
(Length x Width)
(mm2)
Basis Weight
(g/m2)
Sheet
Thickness (µm)
Sheet Volume
(mm3)
Specific
Volume
(dm3/kg)
Moisture
(%)
Range 307-1797 4416-26030 59-92 263-712 2069-14015 4.1-7.8 63 – 86
Average 1332 18861 72 440 7809 6.0 72
NA-SN-4 1797 22196 81 631 14015 7.8 63
NA-SN-6 1631 22125 74 449 9943 6.1 64
Physical Properties of Flushable Wet Wipes from North America (dry state)
Physical properties of flushable wipe samples from European
Countries (as received)
I.D. Sheet Mass
(mg/sheet)
Surface Area
(Length x Width)
(mm2)
Basis Weight
(g/m2)
Sheet Thickness
(µm)
Sheet Volume
(mm3)
Specific
Volume
(dm3/kg)
Additional
Info.
Range 2853-5196 19998-26880 117-244 150-397 3343-9314 0.8-2.7
Average 4363 23384 188 297 6952 1.6
EU-SN-14 3943 22154 178 255 5654 1.4 Toddler wipe
I.D. Sheet Mass
(mg/sheet)
Surface Area
(Length x Width)
(mm2)
Basis Weight
(g/m2)
Sheet Thickness
(µm)
Sheet Volume
(mm3)
Specific
Volume
(dm3/kg)
Moisture
(%)
Range 1020-1599 19500-25350 48-69 174-378 4128-8836 3.7-6.8 61-76
Average 1335 22323 60 299 6650 5.0 69
EU-SN-14 1052 20200 52 352 7114 6.8 73
Physical properties of flushable wipe samples from European
Countries (dry state)
PHYSICAL DISINTEGRATION
Theory
Time = 0
Main product
Time = t1
Intermediate size solids
Time = t2
Small size solids
Physical disintegration is controlled by
Solid characteristics – density, fiber matrix, mechanical strength – represented with disintegration rate coefficient (k)
Turbulence in water – shear forces that break up solids – represented with Reynold’s Number (Re) = depth(d)·water velocity(v)·density(ρ)/ viscosity(µ)
f1
Main
Product
(>12 mm)
8-12 mm
4-8 mm
f2
f3
f4
f5
f6
Size Ranges: (8-12) mm (4-8) mm (<4) mm
MATHEMATICAL MODEL
]12Re[]12[
1 mmkdt
mmd
])128Re[(]12Re[])128[(
211 mmkmmkfdt
mmd
])84Re[(])128Re[(]12Re[])84[(
32412 mmkmmkfmmkfdt
mmd
])84Re[(])128Re[(]12Re[])4[(
32513 mmkmmkfmmkfdt
mmd
Mass Balance Equations for a Batch System:
The model has been tested previously with tampons and toilet papers
It should capture disintegration of wet wipes
We conducted experiments with various wipe samples to obtain for disintegration coefficients (k) and distribution ratios (fj)
We used the model to capture disintegration patterns of the wipe samples
MATHEMATICAL MODEL
Disintegration
Experiments
Representative Discharge Rates of Wet
Wipes and Water
WIPE DISCHARGE RATES:
Average of 1 sheet, and a maximum of 2 sheets per flush (4-6) L.
WATER DISCHARGE RATES:
Minimum of 1 and maxium of 5 flushes per person per day.
4-6 litres of water per flush, and, 4 to 30 litres of water per person per day.
Maximum - 2 sheets are discharged with one flush (4-6) L per day:
2 sheets / 4 L = 0.5 sheet / L – Experimental testing
Experimental case: 2 sheets with 1 flush (4 L) of water
EXPERIMENTAL TESTING
½ Sheet of Wet Wipe
1 L tap water into 2.8 L Fernbach Flask
Rotating Shaker - Turbulence
Sampling – Wet Sieve Analysis
Dry mass measurements
Sampling - Wet Sieve Analysis
12 mm
8 mm
Experimental Results
Day 0 Day 5
Day 9 Day 10
Day 0 Day 3
Day 6 Day 10
Intermediate and small size
solids (47%)
Large size solids = Intact main
product (53%)
After 3 hours
EXPERIMENTAL AND MODELING
RESULTS
PRODUCT: F-NA-No-4 (0.5 sheet/L at 200 rpm)
Experimental and Modeling Results
A B
C
D
Disintegration rate coefficients and fractional distribution ratios
Fractional distribution ratios (fi)
Solid size range
ki·Re
(hour-1)
8 - 12 mm
%
4 - 8 mm
%
<4 mm
%
Total
%
> 12 mm 0.5 75 15 10 100
8 - 12 mm 1.24 25 75 100
4 - 8 mm 0.11 100 100
PRODUCT: F-US-No-4
TRANSLATION OF RESULTS TO WASTEWATER SYSTEMS
Comparison of Experimental
System to Sewer Environment
Comparison of turbulence levels in experimental setup (200 rpm) to
those of partial flow conditions in sewer pipes
Compute and compare Re numbers between the two systems
%60
%10
Turbulence levels in rotating fluid in the experimental system
Turbulence levels in sewer pipes
(a) (b)
(c) (d)
KEmean = ΣmiVi2 / M
Estimated Parameters
Mean Kinetic Energy:
Average velocity:
Vave = SQRT (KEmean)
Reynold’s Number:
Re = Vave· d · ρ / µ
y = 270.28x - 1135.2R² = 0.9407
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
0 50 100 150 200 250 300 350
Re
Num
ber
Rotations per minute rpm (1/minute)
Re Numbers for 1 L water rotating at 64-300 rpms
Re at 200 rpm => Re = 270,3*(200) – 1135,2 => Re = 52900
Representative Sewer Pipes
Pipe type Diameter (inches)
Notes
Household drains 4-6
Small sewer pipes 8-12 8 inch is the smallest sewer pipe in the USA
Mid-size sewer pipes 15-20 Suitable for city streets with low population density, e.g., Tempe, Mesa
Mid-to-large size sewer pipes 24-40 Suitable for densely populated streets
Reynold’s Number for wastewater flow in pipes
Re = (v·r·w) /
Where v: flow velocity, r: hydraulic radius, : wastewater density, and : viscosity
Manning’s Equation for flow velocity:
v = (1/n) · r(2/3) · s(1/2)
Where n: pipe coefficient, r: hydrualic radius, and s: pipe slope
Pipe Diameter
(inch - cm)
Hydraulic radius (rpartial) (cm) Flow velocity at partial flow (vpartial) (cm/sn)
% 10 fill-ratio
(rpartial-10)
% 60 fill-ratio
(rpartial-60)
% 10 fill-ratio
(vpartial-10)
% 60 fill-ratio
(vpartial-60)
6 – 15 0,95 4,16 0,94 0,71
8 – 20 1,27 5,55 0,88 0,68
12 – 30 1,91 8,33 0,88 0,68
15 – 40 2,54 11,10 0,93 0,68
18 – 45 2,86 12,49 0,90 0,66
20 – 50 3,18 13,88 0,87 0,65
24 – 60 3,81 16,65 0,91 0,65
28 – 70 4,45 19,43 0,94 0,65
32 – 80 5,08 22,20 0,94 0,68
%60
%10
Pipe Diameter
(inch - cm)
Re Number
(dimensionless)
Corresponding Rotational Speed
(1/minute)
Minimum Maximum Minimum Maksimum
6 – 15 8840 29209 37 112
8 – 20 10070 39582 45 151
12 – 30 16562 56283 65 212
15 – 40 23485 75138 91 282
18 – 45 25572 81814 99 307
20 – 50 27484 89054 106 334
24 – 60 34280 106643 131 399
28 – 70 41211 125934 157 470
32 – 80 47265 148678 179 554
Re value in our experimental system (52900) is comparable with average Re
value (49200) of waste water flow in small-to-mid size sewer pipes
Conclusions and Future
Only a few wipe samples disintegrate completely, while most wipes show partial or no disintegration
Building drains (D: 4-6 inches) and small sewer pipes (D: 8-20 inches) are critical parts of sewer networks where disintegration will be limited under most flow conditions.
In most sewer pipes (D: 20 – 40 inches), wet wipes will disintegrate very slowly under low flow conditions as in summer days.
Performance criteria and standards must be developed for flushable products to ensure sustainability of wastewater systems
Consumer expectations must be evaluated along with environmental concerns to optimize a product’s functional and environmental performance.
Conclusions and Future
Conclusions and Future
Disintegration rate coefficients and fractional distribution ratios can be integrated into existing sewer models to predict how flushable products will behave in sewer systems. Below is an example for tampons.
PUBLICATIONS
Water Environment Research, 2009, 81 (5), pp. 459 - 465
Water Environment Research, 2012, 84 (5), pp. 424 - 433