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