EPA-660/2-73-037
January 1974
Environmental Protection Technology Series
Modular Wastewater Treatment System
Demonstration for The Textile
Maintenance Industry
Office of Research and Development
U.S. Environmental Protection Agency
Washington. D.C. 20460
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental studies
This report has been assigned to the ENVIRONMENTAL
PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and
methodology to repair or prevent environmental
degradation from point and non-point sources of
pollution. This work provides the new or improved
technology required for the control and treatment
of pollution sources to meet environmental quality
standards.
EPA REVIEW NOTICE
This report has been reviewed by the Office of Research and
Development, EPA, and approved for publication. Approval does
not signify that the contents necessarily reflect the views
and policies of the Environmental Protection Agency, nor does
mention of trade names or commercial products constitute
endorsement or recommendation for use.
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EPA-660/2-73-037
January 1974
MODULAR WASTEWATER TREATMENT SYSTEM
DEMONSTRATION FOR THE TEXTILE MAINTENANCE INDUSTRY
By
Gary Douglas
Project 12120 FYV
Program Element 1BB037
Project Officer
Arthur Mallon
Environmental Protection Agency
Washington, D.C. 20460
Prepared for
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402- Price $3.45
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ABSTRACT
An industrial waste survey of the textile maintenance industry was
performed to characterize and quantify the pollutants emanating from
various types of laundry plants. Bench scale waste treatment tests
were performed to design a system for the textile maintenance industry.
A wastevater treatment system consisting of chemical treatment and floccu-
lation facilities, dissolved-air flotation for solids-liquid separation,
diatomaceous earth filtration for polishing the flotation effluent, and
vacuum filtration dewatering of flotation scum was installed at a
commercial laundry.
Data was obtained on effluent quality, sludge volume, chemical costs and
other operating costs for industrial laundry wastewater, linen laundry
wastewater, and uniform laundry wastewater. The final effluent of the
linen and uniform laundry wastewater treatment met municipal sewer
ordinance requirements for grease and heavy metals. Wastewater suspended
solids and BOD were also significantly reduced, so that high municipal
sewer surcharges would not be Imposed. The effluent from the industrial
laundry wastewater treatment did not consistently meet municipal sewer
ordinance standards.
Complete wastewater treatment operating costs were on the order of
$0.80/cu m ($3.00/1000 gal.) for industrial laundry wastewater, $0.66/
cu m ($2.50/1000 gal.) for uniform laundry wastewater and $0.40/cu m
($1.52/1000 gal.) for linen laundry wastewater. It was concluded that
the treatment system had applicability in treating laundry wastewater.
This report was submitted in fulfillment of Contract No. FYV 12120 by the
Linen Supply Association of America and the Institute of Industrial
Launderers under the partial sponsorship of the Environmental Protection
Agency. Work was completed as of May 1973.
ii
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CONTENTS
Page
Abstract ii
List of Figures iv
List of Tables vi
Acknowledgments xiii
Sections
I Conclusions 1
II Recommendations 4
III Introduction 6
IV Modular Laundry Wastewater Treatment System Design 8
V Industrial Laundry Wastewater Treatment System Operation 71
VI Uniform Laundry Uastewater Treatment 122
VII Linen Laundry Wastewater Treatment 147
VIII Recommended Wastewater Treatment Practice for the
Laundry Industry 175
IX References 182
X Glossary 184
XI Abbreviations 188
XII Appendices 190
Appendix A 191
Appendix B 214
Appendix C 227
Appendix D 313
Appendix E 319
Appendix F 322
Appendix G 340
iii
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FIGURES
No. Page
1 Laundry Wastewater Distribution System 9
2 Variation of pH with Tine for Sewer Discharge on
March 3, 1971 20
3 Variation of Total Solids with Time for Sewer Discharge
on March 3, 1971 21
4 Variation of Total Organic Carbon with Time for Sewer
Discharge on March 3, 1971 22
5 Variation of pH and Suspended Solids with Washing
Operation for a 364 kg Load of Print Wipers 26
6 Variation of Total Solids and TOG with Washing Operation
for a 364 kg Load of Print Wipers 27
7 Carryover of Silica in Succeeding Wash Cycles for a
364 kg Load of Machine Wipers 30
8 Variation of Laundry Sewer Discharge pH with Time on
April 15, 1971 39
9 Correlation of pH and Wastewater Alkalinity for Grab
Samples of April 15, 1971 42
10 Industrial Laundry Wastewater Treatment Flow Sheet 56
11 Diatomaceous Earth Filter Schematic Diagram 63
12 Process and Instrumentation Diagram for Laundry Waste
Treatment System 65
13 Variation of Treatment System Solids with Time on
October 11, 1972 81
14 Variation of Raw and Effluent Wastewater pH and TOC with
Time for November 10, 1972 Wastewater Treatment
System Operation 84
15 Variation of Several Wastewater Characteristics with Time
for November 10, 1972 Wastewater Treatment System
Operation 85
iv
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No. Page
16 Effect of Sludge pH on Filterability for Three Different
Mixes of Laundry Wastevater 89
17 Effect of Various Ratios of Print Wiper Scum and
Machine Wiper Scum on Scum Filterability 90
18 Effect of Calcium Chloride Dosage on Flotation Effluent
Grease and Surface Overflow Rate on Effluent
Suspended Solids 101
19 Laundry Washroom Water Costs Including Fresh Water Sewer
Surcharges and Sewer Use Charges for 100 Laundries 117
•
20 Variability of Wastewater Quality with Time at the
Sewer Discharge for a Uniform Laundry on 5/24/72 128
21 Variability of Filter Yield with Uniform Flotation Scum
Solids 139
22 Laundry Wastewater Reuse Proportions 179
A-l Water Consumption Vs. Industrial Laundry Size 198
A-2 Water Consumption Vs. Linen Laundry Size 199
A-3 Linen Laundry Washroom Costs Including Sewer Use Taxes
Fresh Water Costs, and Sewer Surcharges as a Function
of Product Unit Weight 202
A-4 Industrial Laundry Washroom Costs Including Sewer Use
Taxes, Fresh Water Costs, and Sewer Surcharges
as a Function of Product Unit Weight 203
A-5 Fresh Water Costs for Laundries 204
A-6 Sewer Use Charges for 100 Laundries 205
A-7 Sewer Surcharges for BOD and Suspended Solids for
Laundries 206
A-8 Laundry Washroom Water Costs Including Fresh Water,
Sewer Surcharges, and Sewer Use Charges for 100
Laundries 208
B-l Test Equipment 222
F-l Diaper Laundry Wash Load Vs. Water Consumption 336
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TABLES
No. Page
1 Typical Laundering Schedule for Shop Towels 12
2 Typical Laundering Schedule for Kitchen Towels 13
3 Industrial Laundry Wastewater Characteristics of Four
Samples 15
4 Chicago Sewer Mandatory Discharge Requirements 18
5 Typical Medium Strength Sanitary Sewage 19
6 Wastewater Analyses of Various Grab Samples of March 3,
1971 23
7 Variation of Wastewater Quality with Washing Operation
for 364 kgs of Print Wipers 25
8 Variation of Wastewater Quality for Machine Wipers with
Washing Operation 28
9 Variation of Wastewater Quality for Dust Mops with
Washing Operations 29
10 Wastewater Quality of Final Rinses for Various Washed
Articles 32
11 Estimated Waste Load Quantities from Washing Operations 33
12 Suspended Solids Analyses of Various Wash Operations of
Various Laundered Articles 35
13 Results of Bench Scale Flotation Tests Using Acid and
Alum Chemical Treatment 37
14 Optimum Alum and Sulfuric Acid Dosages for Wastewater
Effluent Grab Samples of April 15, 1971 41
15 Results of Bench Scale Flotation Tests Using Calcium
Chloride Chemical Treatment 43
16 Results of Bench Flotation Testing Performed on the
April 15 Composite Sample Using an Bnulsion Breaker 45
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No. Page
17 Chemical Treatability Characteristics of Individual Articles
Utilizing Three Different Chemical Systems 46
18 Chemicals That Would Not Treat Laundry Wastewater
Effectively 47
19 Scum Characteristics from Two Types of Chemical Treatment
Flotation Bench Scale Testing 48
20 Filter Cloths Used in Bench Scale Filter Leaf Tests 50
21 Recommended Vacuum Filter Characteristics and Operating
Conditions Obtained from Leaf Tests Conducted on
Flotation Scum 51
22 Removal of Heavy Metals by Calcium Chloride Treatment
and Bench Scale Flotation of Industrial Laundry
Wastewater 53
23 Rotary Precoat Vacuum Filter Test Results of Chemically
Treated Industrial Laundry Wastewater 55
24 Bench Scale Design Criteria for the Industrial Laundry
Wastewater Treatment System 57
25 Process Variables to be Investigated for Laundry
Wastewater Treatment 68
26 Laundry Wastewater Analyses to be Performed on Composite
Samples 70
27 System Operating Conditions for Runs of July and August,
1972 72
28 Results of Vacuum Filter Operation of July and August,
1972 73
29 Initial Industrial Wastewater Treatment Results 74
30 System Operating Conditions for October 11 to October
20, 1972 7.7
31 Wastewater Quality for Five Test Days Between October
11 and October 20., 1972 78
vii
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No. Page
32 Removal of Heavy Metal Contaminants by the Industrial
Laundry Wastewater Treatment System on October 20, 1972 80
33 Proportions of Printer's Towels in the Total Laundry
Wash Volume 82
34 Average Characteristics of Print and Machine Wiper
Wastewater for November 10, 1972 86
35 Chemical Characteristics of Scums Used in Laboratory
Testing 88
36 Heavy Metal Content of Two Laundry Flotation Scums 91
37 Waste Treatment System Operating Conditions of January
9 to 11, 1973 94
38 Laboratory Analytical Results for January 9 to 11, 1973 95
39 Vacuum Filter Results for Various Ratios of Printer's
Towels 96
40 Effect of Varying Time Interval Between Calcium Chloride
Addition and Polyelectrolyte Addition on Afterfloc
Formation for Industrial Laundry Wastewater 98
41 Changes in Flotation Effluent Quality with Treatment
System Changes 102
42 Waste Treatment Efficiencies for Various Parameters in
Industrial Laundry Waste Treatment 104
43 Average Contaminant Concentration Achieved in the
Industrial Laundry Treatment System 105
44 Ranges of Waste Treatment Efficiencies for the
Industrial Laundry Waste Treatment System 107
45 Ranges of Wastewater Quality for the Industrial Laundry
Wastewater Treatment System 108
46 General Optimum Operating Conditions for the Industrial
Laundry Waste Treatment System 112
47 Industrial Laundry Wastewater Treatment System
Operating Results 114
viii
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No. Page
A8 Industrial Laundry Waste Treatment Costs in c/Cubic Meter 115
49 Reuse Wastewater Analyses for Two Loads of Shop Towels on
January 30, 1973 119
50 Variation of Wastewater Quality with Washing Operation
For Synthetic Pants 123
51 Variation of Wastewater Quality with Washing Operation
for Synthetic Shirts 123
52 Variation of Wastewater Quality with Washing Operation
for Uniforms ' 124
53 Wastewater Quality of Final Rinses for Various Laundered
Items at the Roscoe Uniform Laundry 126
54 Estimated Waste Load Quantities from Uniform Laundering
Operations 127
55 Composite Wastewater Analyses of Uniform Laundry
Wastewater on March 23 and 24, 1972 129
56 Analysis of Print Wiper Suds at the Roscoe Uniform
Laundry on March 24, 1972 131
57 Results of Bench Scale Flotation Tests of Uniform
Laundry Composite Samples of March 23 and 24, 1972 132
58 Average Wastewater Quality for Uniform Laundry
Wastewater Treatment 135
59 Ranges of Wastewater Quality Encountered in Uniform
Laundry Wastewater Treatment 136
60 General Optimum Operating Conditions for the Uniform
Wastewater Treatment System 140
61 General Operating Results of the Uniform Treatment
System 141
62 Uniform Laundry Waste Treatment Costs in c/Cubic Meter 143
63 Reuse Wastewater Analyses for Two Loads of Synthetic
Pants 144
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No. Page
64 Variation of Wastewater Quality with Washing Operation
for a 364 kg Load of Kitchen Towels 149
65 Variation of Wastewater Quality with Washing Operation for
a 136 kg Load of Tablecloths 150
66 Estimated Waste Load Quantities from Various Laundered
Items 151
67 Waste Characteristics of Linen Composites of May 20, 1971 153
68 Bench Scale Flotation Tests Conducted on Linen Composite
Sample of May 20, 1971 154
69 Water Quality of Diatomaceous Earth Filtered Linen
Flotation Effluent as Compared to Linen Final Rinse
Quality of May 20, 1972 156
70 Comparison of Linen Wastewaters Obtained on Various
Dates and From Various Laundries 157
71 Results of Flotation Testing of Linen Wastes of 1/10/73 159
72 The Effect of Varying the Time Interval Between Calcium
Addition and Polyelectrolyte Addition on the
Formation of Afterfloe on Linen Laundry Wastewater 161
73 Linen Wastewater Treatment Effluent Quality Data 163
74 Type of Linen Soil Handled by the Wastewater Treatment
System for Each Test Day 165
75 Optimum Operating Conditions for the Linen Laundry
Wastewater Treatment System 168
76 General Operating Results of the Linen Laundry Treatment
System 169
77 Operating Costs for Linen Laundry Wastewater Treatment
in c/Cubic Meter 171
78 Linen Laundry Wastewater Reuse Testing for Table Linen 173
79 Required Water Quality for Heat Exchangers 178
80 Laundry Wastewater Reuse Cost Analyses 181
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No. Page
A-l IIL - LSAA Survey Form for Laundry Wastewatcr Treatment
Project 194
A-2 Average Water Costs and Usage for 96 Linen and Industrial
Laundries 196
A-3 Comparison of Water Costs and Usage for Linen and Industrial
Laundries 201
A-4 Ranges of Sewer Discharge Standards for Approximately 20
Municipal Sewer Ordinances 209
A-5 Industrial and Linen Laundry Responses to' the Laundry
Industry Survey 210
C-l Industrial Laundry Survey Wash Wheel Discharge Data 228
C-2 Uniform Laundry Survey Wash Wheel Discharge Data 238
C-3 Linen Laundry Survey Wash Wheel Discharge Data 245
C-4 Industrial Laundry Wastewater Treatment System
Operating Conditions 254
C-5 Vacuum Filtration Operating Conditions for Industrial
Laundry Wastewater Treatment 256
C-6 Laboratory Analysis for Industrial Wastewater Treatment 258
C-7 Uniform Waste Treatment System Operating Conditions 277
C-8 Vacuum Filtration Operating Conditions for Uniform
Laundry Wastewater Treatment 278
C-9 Laboratory Analysis for Uniform Wastewater Treatment 279
C-10 Linen Laundry Waste Treatment System Operating Conditions 287
C-ll Vacuum Filtration Operating Conditions for Linen Laundry
Wastewater Treatment 290
C-12 Laboratory Analysis for Linen Wastewater Treatment 292
D-l Mathematical Incineration Model Test Case Conditions 315
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No. Page
D-2 Case 1 - On Site Fluidized Bed Laundry Sludge Incineration
Costs 316
D-3 Case 2 - On Site Fluidized Bed Laundry Sludge Incineration 317
F-l Variation of Wastevater Quality with Washing Operation
for 182 kgs of Diapers (Load 1) 325
F-2 Variation of Wastewater Quality with Washing Operation
for 182 kgs of Diapers (Load 2) 326
F-3 Variation of Wastevater Quality with Washing Operation
for 273 kgs of Diapers (Load 1) 327
F-4 Variation of Wastewater Quality with Washing Operation
for 273 kgs of Diapers (Load 2) 328
F-5 Estimated Waste Loads From Diaper Laundering 330
F-6 Wastewater Characteristics of Diaper Laundry Composites
of 12/17/71 332
F-7 Results of Bench Scale Flotation Test for Diaper Laundry
Composites of 12/17/71 333
F-8 Average Water Usage and Water Costs for 20 Diaper
Laundries 335
F-9 Diaper Industrial Survey Responses Regarding Water
Consumption and Cost 338
xii
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ACKNOWLEDGEMENT S
The support of the following organizations during the course of this pro-
ject is acknowledged with sincere thanks.
Linen Supply Association of America (LSAA)
Institute of Industrial Launderers (IIL)
Laundry and Cleaners Allied Trade Association (LACATA)
KEX National Association
National Institute of Infant Service
The cooperation and assistance of thses organizations was of considerable
aid in facilitating the work performed. In particular, the cooperation and
interest of Mr. Robert B. Knaggs of LSAA (now of Broward Linen Service) and
Mr. Charles Humphrey of IIL are gratefully acknowledged.
Likewise, Mr. Donald Buik, President of The Roscoe Co., and his chief en-
gineer, Mr. Daniel Uhlir, are gratefully acknowledged and thanked for all
the work and assistance they provided in locating the treatment system in
their plant, helping set it up, and in general trouble shooting. The en-
tire maintenance staff of The Roscoe Co. helped considerably in getting the
treatment system operating and in keeping it operating, and this is deeply
appreciated.
This investigation was carried out by the Environmental Sciences Division
of Envirex Inc. Dr. Robert Agnew directed the work, and Mr. Gary Douglas
is the author of this report. The bench scale studies, analytical determi-
nations and statistical investigations were conducted by Mr. R. Wullschleger
and his staff. Their efforts and diligence were essential to the collection
and evaluation of the data presented. Messrs.F. Toman and R. Christensen
are thanked for actual unit operation and sampling. The brunt of the typing
was born by Susan Bauer, Sylvia Louderback and Betsy Kisnoski, whose dili-
gent efforts facilitated the presentation of this manuscript.
The support of the project by the Environmental Protection Agency, formerly
the Federal Water Quality Administration, and the willing assistance and
helpful advice of Project Officer Mr. Arthur Mallon in the conduct of the
project and in the presentation of this report is acknowledged with sincere
thanks.
xili
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SECTION I
CONCLUSIONS
The following conclusions can be made based on the data obtained from
this study, as applied specifically to the operation at the Roscoe
Laundry and their laundry formula:
1. Uniform and linen laundry wastewater, as defined in this report,
may be treated by coagulation, dissolved-air flotation and
diatomaceous earth filtration to meet most presently applicable
sewer discharge standards.
2. Industrial laundry wastewater, as defined in this report,
requires additional treatment, more c-msistent raw wastewater
quality, or different treatment unit operation to meet
municipal sewer standards consistently.
3. Calcium chloride coagulation followed by solids separation is
an effective heavy metals separation technique for the laundry
formula and wastewater investigated in this study. Laundries
using different wash formulas may not find calcium chloride
treatment effective.
4. The amortization and operation costs for this demonstration
system were found to be as follows:
industrial laundry $0.77/cu m (cubic meter) or $2.90/1000
gallons (gal.)(See Section V for detailed
breakdown)
uniform laundry $0.67/cu m or $2.53/1000 gal. (See
Section VI for detailed breakdown)
linen laundry $0.40/cu m or $1.52/1000 gal. (See
Section VII for detailed breakdown)
Bulk chemical handling and alternate sludge handling facilities for
linen laundries and bulk chemical handling for uniform and
industrial laundries will reduce the operating costs for the
demonstration system to:
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industrial laundry $0.71/cu m ($2.70/1000 gal.)
uniform laundry $0.60/cu m ($2.29/1000 gal.)
linen laundry $0.32/cu m ($1.21/1000 gal.)
5. Up to ninety percent removals of iron, lead, copper and zinc
were obtained for uniform and industrial laundry wastewater.
Mercury and cadmium are also significantly reduced in concen-
tration by the treatment process.
6. The laundry washload of printer's towels had to be maintained at
less than 15% of the wash poundage at any one time to Insure
effective operation of the treatment system.
7. The sludge volumes generated by various types of laundry waste-
water are as follows:
industrial laundry 2% to 4% of the raw waste volume
uniform laundry 1% to 2% of the raw waste volume
linen laundry 0.4% to 0.8% of the raw waste
volume
8. No sewer surcharges will be incurred for linen laundry or
uniform laundry wastewater treatment system effluent at this
plant. A surcharge might have to be paid for the industrial
laundry wastewater treatment system effluent.
The following conclusions can be made based on the data obtained from
this study, regarding laundry wastewater treatment in general:
1. Wastewater treatment is not cheap or easy, but is a complex
problem requiring resolution by a competent engineering firm.
2. As the complexity of the wastewater decreases, the treatability
and consistency of treatment Improve considerably.
3. There is no economic benefit in treating laundry wastewater to
reduce sewer surcharges for suspended solids and biochemical
oxygen demand (BOD), .as treatment costs will usually exceed
the surcharge* If a linen wastewater treatment system is
installed in a high sewer surcharge and water cost area, treat-
ment conceivably could produce cost savings, but this would
be an unusual situation.
4. Wastewater age is a significant variable in designing linen
laundry treatment systems. Bench tests for linen wastewater
should be performed on the freshest samples possible to prevent
significant changes in wastewater treatability from occurring.
5. Wastewater reuse has potential in producing wastewater treatment
cost savings dependent upon water costs.
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6. Most laundry wastewater treatment installations will have to be
custom designed from mechanical and configurative standpoints
due to space limitations of many plants.
7. Wastewater reuse is feasible with a separate water storage and
heating system for the wastewater treatment system effluent.
Only city softened water should be used for boiler feed water.
Separate programming of washing machines for effluent water is also
required if it is not feasible to use this water for final rinses.
8. The wastewater effluent is good enough to clean articles without
harming them, but is high in dissolved solids and calcium
hardness, thus limiting its reuse potential. The presence of
dyes can also limit the water's reuse value, as this is not
removed in the treatment process. The water will have to be sof-
tened to be reused in the laundering process.
9. If the wash load of a laundry is seasonal, or the wash load
proportions change radically over a period of time, e.g.,
industrial to linen, it must be known prior to designing a
wastewater treatment system. A change in the wash mix can
render a wastewater treatment system ineffective, as could the
addition of new customers of industries radically different from
the normal laundry clientele.
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SECTION II
RECOMMENDATIONS
It is recommended that:
1. All laundries whose wash load is greater than fifty percent shop
towels who are contemplating wastewater treatment, or who have a
heavy metal problem, perform pilot plant (not laboratory) waste-
water treatment studies in order to obtain design information for
a large scale treatment system.
2. Equalization time at least equal to the length of one complete wash
cycle be provided for all laundry wastewater treatment plants.
3. The treatment system concept employed for this demonstration plant
be evaluated on a laboratory basis by all laundries considering waste-
'water treatment before installing a cheap "miracle" wastewater
treatment system. Laundry owners should be aware that waste treat-
ment is not easy or cheap, and be leery of package plants that fit
into small areas.
4. Any treatment system installed be located away from areas of produc-
tion activity, if possible, in order to facilitate maintenance; and
that approximately 0.074-0.098 square meters (sq m) of floor space,
with due consideration of head room, be allocated for each 1pm of
treatment capacity (3 to 4 sq ft/gpm capacity). This area require-
ment does not include space for wastewater equalization.
5. More information on the effect of laundry supplies on the treatment
process be obtained to more adequately define the applicability of
this treatment concept. Different wastewater coagulants may be
required for different laundry formulas.
6. More information on the variability of laundry wastewater from plant
to plant within the same wash category be obtained to establish if
the variability is significant and if this significantly affects
wastewater treatment results.
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7. More extensive Information on laundry water costs, treatment problems
and profit margins be obtained so that waste treatment break even
analyses can be performed for a variety of wastewater treatment cases
to more completely define the magnitude and scope of the national
laundry water pollution problem.
8. The above information be obtained from wastewater samples from as
many laundries as possible by bench scale application of the
demonstration system treatment concept so that treatment costs and
effluent quality data are available for a variety of laundry
circumstances. This same survey should obtain cost and wash formula
information from each subject laundry such that treatment costs and
a treatment system flow sheet can be developed for that laundry. If
this is done for a dozen or more laundries, the scope of the treat-
ment problem and the universality of the applicability of the demon-
strated treatment concept can be accurately defined.
9. The same type of information as outlined in Recommendation No. 8 be
developed for various laundry wash mixes, i.e., different percentages
industrial, uniform, and linen.
10. The 1971 survey of Appendix A be periodically updated.
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SECTION III
INTRODUCTION
The early portion of the 1970's has experienced a pronounced increase in
governmental activity in the area of water pollution control legislation
and regulation. In 1971, the 1899 Refuse Act was uncovered by the
Congress and enforced by the Army Corps of Engineers. All industries
discharging any water to a storm sewer or receiving body of water had to
file for a permit to discharge with the Army Corps of Engineers and
provide them with a detailed chemical analysis of their waste discharge.
In 1972, the United States Congress passed a water pollution control bill
aimed at eliminating water discharges by 1985. Many municipalities and
counties are now tightening already existing water pollution control and
sewer discharge ordinances or passing new ones. Local governments are
doing this to comply with strict federal regulations, and are doing it
in the easiest manner possible - by shifting the burden of cleaning the
water to the producer of the wastewater. This has caused a variety of
water pollution control problems for industry and has forced many
specific industries to seek a solution to their water problems and
provide waste treatment.
Not the least of those industries affected by these and related develop-
ments are commercial laundries of various types; linen, uniform, diaper,
shop towel, etc. This is significant when one considers that laundry
wastes from all sources make up 5% to 10% of all municipal wastewater(1).
It can be appreciated that this percentage becomes even more significant
when one considers that the suspended solids and biochemical oxygen
demand (BOD) of laundry wastewater can be from 3 to 20 times higher than
average domestic sewage, if the average suspended solids and BOD of muni-
cipal wastewater are considered to be 250 milligrams/liter (mg/1) (1)(2)(3).
The concentration of these pollutiohal parameters is dependent upon type
of laundry, type of laundry formulation used for cleaning, laundry
location, general laundry housekeeping practices, laundry customer
habits, etc. Other areas of concern for various laundry wastewaters
include high alkalinity, color, grease, and assorted heavy metals.
Generally, almost all laundries can be in violation of common municipal
sewer ordinances regarding any of the above parameters, dependent upon
a variety of considerations. High strength wastes in terms of BOD and
suspended solids may also lead to excessive wastewater surcharges,
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a tax on wastewater strength, for certain laundries. Subsequent waste-
water treatment conceivably could lower these charges, if the waste-
water treatment cost was lower than the surcharges.
The above considerations led to the Linen Supply Association of America
contracting the Rex Chainbelt Technical Center to do a bench scale waste
treatment feasibility study for linen laundry wastes (2). From this
study, several promising wastewater treatment processes were developed,
not only for treating the wastewater for discharge, but also for reusing
it in the wash process.
Based on the results of this study, it was decided to construct and operate
a 757 liter per minute (1pm)(200 gallons per minute) laundry wastewater
treatment demonstration system at a laundry washing a variety of articles.
General laundry wastewater treatment feasibility could then be demonstrated
for a variety of laundry wastes. Consequently, a project involving the
installation, operation and evaluation of a laundry waste treatment
system consisting of chemical treatment, dissolved air flotation, diato-
maceous earth filtration, and vacuum filtration dewatering of residual
sludge was initiated. (Development of this concept is completely out-
lined in Referenced.) This project was funded, in part, by the
Environmental Protection Agency Grant No. 12120 FYV and in part by the
Linen Supply Association of American, the Institute of Industrial
Launderers, and various other laundry organizations and institutions
enumerated in the Acknowledgments. The resulting project was divided
into two phases:
I. Design, Fabrication and Planning of Prototype Equipment
II. Operation and Evaluation of System
This report summarizes the work performed in the above two phases in the
design, installation, operation and evaluation of a modular laundry
wastewater treatment system coupled with water reuse in the laundering
process.
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SECTION IV
MODULAR LAUNDRY WASTEWATER TREATMENT SYSTEM DESIGN
DESCRIPTION OF LAUNDRY SELECTED FOR TREATMENT SYSTEM INSTALLATION
The laundry selected for the installation of the wastewater treatment
system is located in Chicago, Illinois and washes shop towels, printer's
towels, dust mops, table linen, kitchen towels, and continuous towels.
The majority of the wash poundage is generally shop and printer's towels.
These two items are also referred to as machine and print wipers
respectively. When this project was initiated in March of 1971, the
laundry's linen wash poundage amounted to about 25% of the total wash
poundage. It was envisioned at this time that the linen wash wastewater
would be segregated from the industrial portion of the wastewater so
that the treatment system could be operated on either linen laundry
wastewater or industrial laundry wastewater. Because of the low volume
of linen cleaned in this plant, it was not possible to wash all .linens
at any one time and run the treatment system. Consequently, linen and
industrial items had to be washed concurrently and a means developed to
separate the two wastewaters.
An old basin of approximately 32.3 cu m (8,500 gal.) capacity was available
for storage of linen wastewater. This could be segregated from the indus-
trial wastewater by the usage of only certain washing machines for linen
laundering and appropriate dams. Figure 1 shows a layout of the laundry
and the trenches which carried the laundry wastewater. The rectangles
marked "l" are industrial washing machines and those marked "L" are
linen washing machines. All machines dump their loads of water Into
trenches directly beneath them. All these trenches drain into a small
pit where the wastewater is pumped into a vibratory screen to remove
large particles from the wastewater. The screened wastewater flows into
the heat reclaimer pit where it is pumped through a heat reclaimer where
zeolite softened city water is preheated by the hot wastewater. The
wastewater then exits from the heat reclaimer and flows out into the
city sewer.
For the purposes of this project, the trench under one of the linen washing
machines was extended.past the already used sewer discharge point to an old
unused 30.5 centimeter (cm) or 12 inch (in.) sewer. This is marked by the
8
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iixcracror / /
>
L
n
i
i
i
t
i
*-*
-H»-
//
/ /
//
||
:J
. j *
p~*i
To
Sewer
/
Dam
w
._ I__ _ _.I __ I I
i i
1 r-,
' 1 1
^^" ~™ — — —* |
Jl Manhole
M
^S>v
\
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\
1
i
^
-4
\
Linen S
I Treatment j
p. «J System Location '
1 i_ _J
Heat Reclaimer ;Creer """00
<£> p" * PIt >-v_
1 I V* — bcreen
\ V J Industrial
\ ^T »- Flow
s* 1 - ^ T. fn*»n Flow
\L = Linen
I = Industrial
Heat Reclaimer p = Pump
m t FT! Installed for
. — 1- • » i
©-- J ''
FIGURE 1
LAUNDRY WASTEWATER DISTRIBUTION SYSTEM
-------
diagonal lines in Figure 1. By placing dams at the two points shovm in Fijmre
1 and usine those washers marked "L" for linen wastes, it was possible to
separate linen wastewater from the industrial wastewater and store it
in the 32.2 cu m pit. The industrial laundry wastewater was taken
directly from the discharge side of the heat reclaimer into the treatment
system. It could go either to the present laundry sewer discharge or the
waste treatment system, or to the linen storage pit. A sump pump in the
linen storage pit was used to pump the linen wastewater back to the treat-
ment system, which was located as shown in Figure 1 between the heat
reclaimer pit and the washing machines.
It may be noted here that the term "industrial laundry wastewater" through-
out this report will be taken to mean that water emanating from the
laundering of shop towels, printer's towels, and dust mops.
Softened city water, after passing through the heat reclaimer, flows to
two water storage tanks where it is heated by steam coils. The steam is
produced by hot water boilers. The preheated water is then brought up
to the required temperature in the storage tank, and is then used in
those cycles requiring hot water. Those portions of the wash cycle using
softened cold water bypass the heat reclaimer system and go directly to
the washers.
LAUNDRY OPERATION
This section of the report will serve to describe general operating
practices of the laundry under consideration. The items cleaned by the
laundry are hauled in by truck and deposited in drums or bags at an
unloading dock. At this point, the wipers are taken to a counting
station, where the wipers are manually counted and sent through a cage
mill to remove metal chips or large pieces of refuse. The linen items
are sorted elsewhere. These counted items fall into large bags that are
then lifted onto a monorail system that conveys them to the washing machine
area. Here the bags are emptied into the washing machines and the wash
cycle started.
Each different item washed has its own laundry formula, which is the type
and amount of cleaning chemicals required. These chemicals are referred to
as supplies. For wipers, this laundry utilizes a formula consisting of
alkali to swell the fibers of the cotton cloth to help loosen the dirt and
grease present. This dirt and grease is referred to as the soil. Silicates
are added to the wash at the same time to provide buffering between the
caustic and cotton fibers. A nonionic detergent is also added to emulsify
the oils and greases present. All these chemicals are added at one time
during one washing operation; where a washing operation is defined as a
portion of the wash cycle providing one batch of wastewater such as a
suds operation, bleaching operation, or rinse operation. After this suds
operation is completed, 6 to 11 rinses may follow to flush out the soil
and supplies. Linen washing is similar except that bleach and a sour
are also added. A sour is an acid chemical added in the last washing
10
-------
machine operation for pH adjustment. Starch is also added to linen
wash loads, as well as other compounds, dependent on what is being laundered,
Thus, each item laundered may utilize different cleaning agents, different
proportions of cleaning agents, different wash operations, and different
volumes of water per wash load.
Tables 1 and 2 present typical laundering schedules for shop towels and
kitchen towels respectively. Schedules for other items would vary
slightly from these. The first operation or flush is merely an initial
rinse to remove readily loosened soil. The suds operation of Table 1
is that operation which emulsifies the oils and greases and loosens all
the soil. The carryover is merely an extension of the suds operation
in that a high percentage of the supplies initially added are still
present. This operation takes advantage of that fact by utilizing the
remaining cleaning ability of the suds chemicals. The carryover is
followed by ten rinses to remove the used detergent and removed soil.
The shop towels are then dyed, with salt added to set the dye. A final
cold rinse also aids in setting the dye and removing excess dye. The
operations outlined in Table 2 are similar, except that the linen wash
load utilizes two suds operations and a bleach and sour operation. A
mildicide is added with the sour. The initial break operation is
similar to a suds operation except that no soap is added. This operation
emulsifies the oils and greases present. The base oil compound added
does this effectively. The soap is then required to remove stains, dirt,
etc.
The laundered items are then unloaded from the washers into stainless
steel tubs. The tubs are rolled into an extractor where excess water is
squeezed out. This water also drains into the heat reclaimer pit. The
clean articles are then taken to gas fired driers where the rest of the
water is evaporated. After this operation, the clean wipers are folded
and packaged into standard bundles and redistributed to the customers.
The linen items follow a similar procedure.
The above considerations and Tables 1 and 2 demonstrate many items that
could cause laundry wastewater to be highly variable in nature. The
many different types of soil, the different laundry formulations for
each soil type, and the different laundry operations as well as the batch
type operation of each washing machine contribute to extreme variability
in flow and contaminant concentrations. Each wash operation presented
in Tables 1 and 2 discharges after its completion, such that with only
one machine discharging, a series of wastewater surges would be received
at some point with each surge being of different wastewater quality than
the one preceding.
During the early part of this project, a survey of the laundry industry
in general was made to determine water usage rates, water costs, washing
practices, application of sewer ordinances, etc. This information was
needed in order to determine the applicability of the wastewater treatment
system to the laundry industry, both in terms of cost and practicality.
However, this information does not have any direct bearing on the technical
11
-------
TABLE 1
TYPICAL LAUNDERING SCHEDULE
FOR SHOP TOWELS
Washing Operation
Flush
Suds
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Rinse 7
Rinse 8
Rinse 9
Rinse 10
Dye
Salt
Cold Rinse
Uater Level
(cm)
45.6
20.4
20.4
45. to
45.6
45.6
45.6
45.6
45.6
45.6
45.6
45.6
45.6
45.6
—
20.4
Temperature
Op
line
190
190
190
190
190
190
190
190
185
175
165
155
145
—
100
Operation
Length
(min. ) Supplies
2
15 NaOH,
silicate &
base oil
4
2
2
2
2
2
2
2
2
2
2
2 Dye
4 Sodium
phlorid
\slH.\J L XU
2
12
-------
TABLE 2
TYPICAL LAUNDERING SCHEDULE
FOR KITCHEN TOWELS
Washing Operation
Flush
Flush
Break
Suds
Rinse 1
High Suds
Bleach
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Sour
Water Level
(cm)
45.6
45.6
20.4
20.4
45.6
45.6
25.4
45.6
45.6
45.6
45.6
15.2
Temperature
°F
Medium
Hot
Hot
Hot
Hot
150°F
Hot
Med ium
Medium
Medium
Cold
Operation
Length
(min)
4
2
5
4
2
4
7
2
2
2
2
4
Supplies
base oil,
alkali
alkali,
soap
Soap,
alkali
Bleach
Sour,
mildicide
13
-------
evaluation of the vastewater treatment system installed at the laundry
under consideration. Consequently, a report summarizing the results of
this survey for industrial and linen laundries is presented in
Appendix A.
The data from this laundry wastewater survey report will b« utilized to
compare treatment system effluent quality with required sewer discharge
standards. It will also be used to compare laundry wastewater treatment
costs to present laundry water usage costs and to determine the amount
of money saved by reducing sewer surcharges on laundry wastewater BOD and
suspended solids. It is common knowledge that municipalities charge
Industries for the amount of BOD and suspended solids they send to the
municipal treatment plant that is above a defined level. This practice
is well documented in the literature (4)(5).
WASTEWATER SAMPLING PROGRAM AND BENCH SCALE TREATMENT PLANT DESIGN
The laundry was first visited in March of 1971 and several times there-
after to obtain both composite and grab samples of the wastewater for
laboratory bench scale testing for sizing the waste treatment equipment.
Initial sampling was also designed to characterize the wastewater
discharging from the plant into the city sewer.
Analytical results for three separate full shift, composite samples and
one grab sample obtained from the subject laundry are presented in Table 3.
The March 16 sample is the grab sample. As can be seen, the range of
wastewater contaminant concentrations is quite large. It is evident that
the wastewater contains an exceedingly high concentration of organic
materials, hexane solubles, and an inordinate alkalinity. All analyses
were performed in accordance with the thirteenth edition of Standard
Methods for the Examination of Water and Wastewater (6). All analytical
methods utilized are detailed and referenced in Appendix B.
These samples demonstrated a wastewater suspended solids variation between
1,946 and 2,380 mg/1 and that the suspended solids may be 27% to 35% of
the total solids. Thus the majority of the solids are dissolved, which
is here defined as those solids passing through a 0.45 v membrane filter
or a standard Gooch crucible with a glass fiber mat in it. Analysis of
sample's other than these demonstrated that 70% to 90% of the total organic
carbon (TOC) was associated with the suspended material (see Table 6).
A good portion of the TOC would be expected to be associated with the
hexane solubles that were measured. The hexane soluble material for the
most part was emulsified oils and greases and a small portion of free oil.
It is possible that during the suspended solids analyses that a portion
of the hexane soluble material was measured as suspended solids due to
absorption on the filter paper during membrane filtration, or absorption
to the walls of a Gooch crucible and filter medium during glass fiber
suspended solids analyses. This could lead to low soluble TOC analyses
because of loss of what could be classified as soluble TOC in the
filtration. The degree of emulsification of the wastewater makes it
14
-------
TABLE 3
INDUSTRIAL LAUNDRY WASTEWATER CHARACTERISTICS
OF FOUR SAMPLES
Sample Date
Analysis
Total Solids, mg/1
TOC, mg/1
Total Volatile Solids, mg/1
Suspended Solids, mg/1
Volatile Suspended Solids, mg/1
Hexane Solubles, mg/1
pH, units
Total Alkalinity as CaC03, mg/1
BOD, mg/1
Phosphorus, mg/1 as P
Silica, mg/1 as Si02
Total Dissolved Solids, mg/1
3/3
6850
4400
3250
2287
1953
493
11.9
1825
1695
1.3
900
4563
3/16
5990
2200
3290
2115
1920
1838
12.0
2200
—
—
1000
3875
4/15
7431
3050
3641
2380
2225
2229
12.6
3190
2482
—
673
5051
5/20
7245
3400
5284
1946
1458
245
11.6
1050
—
—
—
5299
* 3 full shift composite samples & one grab sample for 3/16
15
-------
difficult to determine the exact nature of the contaminants present.
It is expected that some of the emulsified oils would pass a membrane
filter and some be absorbed by the solids being filtered. Thus, some
emulsified oils" and greases would show up as suspended material part of
the time, and some would not. If the same emulsion could not be
completely broken by the procedure for hexane solubles in reference 6,
then a portion of the emulsion may not be measured in the hexane soluble
testing. Large greasy particulates would be measured as hexane solubles.
These facts make it difficult to distinguish between the exact amounts of
particulate soil and greases since some non-particulate matter may show
up as suspended solids, and some particulates as grease. Likewise it
may be noted that the wastewater contained a quantity of solvent materials
which might interfere with waste treatment, but do not show up in any
solids analyses measured by evaporating a portion of the waste at 102°C.
At this temperature, some volatile substances present would evaporate
with the water and not appear as total solids.
A typical sample of the wastewater is a black or dark colored colloidal
suspension which does not settle at all upon standing for many days.
The wastewater can best be described as a thin oily mud. The material
that comprises or contributes to the wastewater contaminants may be any
material present in the shop towels and printer's towels being washed.
The types of materials which may come from the machine wipers include
greases and oils from tool and die operations, filling stations, and
all-types of factories where shop rags are utilized. The print wipers
may contain paints, varnishes, lacquer, latex rubber, ketone solvents,
or inks utilized in catalog and candy wrapper manufacture, as well as
carbon black and other materials utilized at newspaper printing plants.
One of the largest print wiper customers of the subject laundry was
contacted in an effort to define the sources of organic pollutants in
the wastewater. They reported that they routinely used over 30 hydro-
carbon solvents, and over 300 dyes, pigments, and inks daily in printing
fliers, catalogs, and the like. The laundry had dozens of such customers
at this time. Thus, the laundry ends up with whatever product its
customers may be using. Consequently, the variety of materials present
in the wastewater is Immense and emphasize the difficulty in inter-
preting the meaning of gross analyses such as total solids, total organic
carbon and hexane solubles. These points, coupled with the analytical
problems, should be considered in all discussions regarding industrial
laundry waste treatment in this report. These same points emphasize the
degree of variability that might be expected in the wastewater both hourly
and daily.
Table 3 also demonstrates that this laundry has a good deal of suspended
solids and BOD associated with it. Thus one of the project goals was
to significantly reduce these contaminants in order to prevent sewage
surcharges. Another project goal was to upgrade the laundry effluent
so that it would meet an already existing Chicago municipal sewer
ordinance regulating discharges, as well as to upgrade the wastewater
16
-------
for potential reuse in the laundering process. The standards of this
ordinance, are presented in Table 4. It is readily discernible that
alkalinity and hexane solubles are definite problem areas, as well as
the suspended and biologically degradable material. The wastewater did
not contain much phosphorus as little synthetic detergent is used at
this plant. In comparison with a medium strength sanitary sewage, the
laundry wastewater is quite strong, as may be seen by comparing Tables 3
and 5. Table 5 presents wastewater characteristics for sanitary waste-
water as reported by Babbitt and Baumann (7). Thus the laundry wastewater
BOD is 8 to 12 times greater, the laundry wastewater suspended solids 6 to
8 times greater, and the laundry wastewater alkalinity 18 to 32 times
greater than a medium strength sanitary sewage. It can thus be appreciated
that this is indeed a high strength industrial waste.
To determine the degree of variability in an operating day, grab samples
of the wastewater going to the sewer were taken every 10 minutes on
March 3, 1971. All samples obtained were analyzed for total solids, total
organic carbon (TOC), and pH. Selected samples were analyzed for suspended
solids and soluble TOC. The results of the laboratory tests for pH,
total solids, and TOC are shown in Figures 2, 3, and 4 respectively. Time
zero occurs at the time the first sample was taken (7:30 am). The time
thereafter represents the number of minutes after this sample was taken.
From these curves, it can be seen that there is a great deal of varia-
bility with time for the TOC, total solids and pH of this waste stream.
The large decrease in pH, TOC, and total solids at about 300 minutes
occurred at lunch break when only the linen washing machines were dumping.
The contaminant concentrations increase again after the lunch period is
over. The total solids reached levels exceeding 15,000 mg/1 and the
TOC reached levels of 13,000 mg/1.
Figure 2 demonstrates the observed variability in the wastewater pH.
It can be seen that the effluent pH was always between 11.0 and 13.0.
Though this does not appear to be a large variation, one should keep
in mind that this represents a variation of two orders of magnitude in
hydrogen ion concentration. It is obvious that this extreme fluctuation
would complicate any pH dependent chemical treatment processes.
Table 6 presents the balance of the analyses performed on these waste
samples. These analyses indicated that the wastevater suspended solids
may vary between 950 and 4,350 mg/1 and were 26% to 40% of the total
solids for those samples tested. The total dissolved solids content for
the wastewater ranged from 1,550 to 6,545 mg/1. These analyses also
show the large variability of the waste stream characteristics.
The degree of variability demonstrated in these samples would be intoler-
able in conventional biological or physical-chemical treatment plants.
The large change in alkalinity would make pH controlled chemical dosages
difficult, and shock organic loadings would interfere with most biolog-
ical processes. This preliminary information demonstrated that waste-
water equalization is desirable.
17
-------
TABLE 4
CHICAGO SEWER MANDATORY DISCHARGE REQUIREMENTS
Concentration
Parameter (mg/1)
Boron 1.0
Chromium (total) 25.0
Chromium (Hexavalent) 10.0
Copper 3.0
Cyanide (total) 10.0
Cyanide (readily released at 150°F
and pH • 4.5) 2.0
Iron 50.0
Lead 0.5
Nickel 10.0
Temperature not over 150°F
pH 4.5 - 10.0 units
Zinc 15.0
Cadmium 2.0
Hexane Solubles 100
Mercury 0.0005
IB
-------
TABLE 5
TYPICAL MEDIUM STRENGTH
SANITARY SEWAGE
Parameters Concentration, «g/l
Total Solids 500
Suspended Solids 300
BOD 200
Alkalinity (as CaO>3) 100
19
-------
13
12 .
1C
4J
§ 11 .
10 -
9 -
8
0
50
100
150
300
350 400
200 250
Time - Minutes
FIGURE 2
VARIATION OF pH WITH TIME FOR SEWER DISCHARGE ON MARCH 3, 1971
450
-------
20,000
60
I
CD
O
cn
OJ
4J
O
H
15,000 -
10,000 .
5,000 -
0
2"00 250 300 350
Time - Minutes
FIGURE 3
VARIATION OF TOTAL SOLIDS WITH TIME FOR SEVER
-DISCHARGE ON MARCH 3, 1971
400
450
-------
NJ
Ni
20,000
15,000 -
c
o
1
u
u
•H
nj
ec
10,000
5,000
450
- \
Minutes
FIGURE 4
VARIATION OF TOTAL ORGANIC CARBON WITH TIME FOR
SEWER DISCHARGE ON MARCH 3, 1971
-------
TABLE 6
WASTEWATER ANALYSES OF VARIOUS GRAB SAMPLES OF MARCH 3, 1971
to
Time - Minutes
After First Sample
0
10
50
80
158
178
250
385
409
435
Suspended
Solids
(rag/1)
2920
—
2100
—
—
950
1150
—
4350
1660
Total Dissolved
Solids
(mR/1)
6230
—
5978
—
—
1730
1550
--
6545
3205
Soluble
TOC
(mg/1)
370
—
725
835
194
—
1208
—
365
Percent
Soluble
TOC
__
9.3
—
33.0
14.2
19.4
—
21.4
—
18.8
-------
Wash Operation Sampling
Further sampling at the laundry was performed to characterize the waste-
water emanating from the washing operations of various articles and to
identify the major pollutant contributors. It was desirable to establish
with which articles and in what wash operation the majority of the
pollutants evolved as well as to obtain an idea of the amount of contami-
nation generated by a unit mass of a particular item. Grab samples were
obtained from each machine dump for the entire washing cycle of print
wipers, machine wipers, and dust mops. Due to the nature of the launder-
ing cycle, each load of water is well mixed by the washer action.
Therefore, a grab sample will be an excellent representation of the waste-
water characteristics generated during that particular washing cycle (8).
All samples obtained were analyzed for total solids, total organic
carbon and pH. Selected samples were analyzed for suspended solids and
soluble TOG.
The results of a typical series of analyses are presented in Table 7 for
a 364 kilogram (kg) (800 pound) load of print wipers utilized by such
industries as catalog and candy wrapper manufacturers. The results of
eleven other sampling cycles for different items displayed similar trends.
The contaminant concentrations varied, however, depending on the article
washed. From Table 7 it may be seen that there is a sharp increase in
total solids, pH, and TOC after the flush. The flush is merely an initial
water rinse. This reflects the addition of the supplies as well as the
removal of contaminants in the wipers. After the suds there is a steady
decrease of TOC, pH and total solids with each succeeding rinse. Graphs
of these data in Figures 5 and 6 reflect this trend. All of the curves
demonstrate a sharp increase after the flush followed by a steady
decrease in contaminant concentration, as the contaminants are washed out
at a decreasing rate. Tables 8 and 9 present similar trends for machine
wipers and dust mops. The addition of dye in the next to last rinse in
these cycles is reflected by an increase in total solids.
These curves clearly show the great variability of wastewater that may
occur during the washing of one load of any item. Each wash operation is
dumped independently of any other one, so that each machine dump may flow
to some point as a slug. Each dump is separated by a period of two
minutes or more. It can be appreciated that a discharge of this type
could cause a very significant variability in wastewater characteristics,
even with several machines operating together, when the various
washing machines are cleaning different articles from many different
laundry customers. This reflects the difficulty one might have in
chemically treating this waste unless alternate provisions, such as
wastewater equalization, are made. This type of information can prove
to be very useful in designing laundry wastewater treatment equipment.
A series of tests for silica were made on the different dumps of a load
of machine wipers to determine the rate at which it is washed out of
the wipers. Figure 7 demonstrates that while essentially all of the
silica has been flushed from the wipers by the seventh rinse, the
majority of the silica had been discharged during the first two operations,
24
-------
TABLE 7
VARIATION OF WASTEWATER QUALITY WITH WASHING OPERATION
FOR 364 KGS OF PRINT WIPERS
Operation
Flush
Suds
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Rinse 7
Rinse 8
Rinse 9
Rinse 10
Rinse 11
Water
Utilized
(liters)
1340
420
420
1340
1340
1340
1340
1340
1340
1340
1340
1340
1340
1340
TOC
(mg/1)
8,500
100,000
58,000
9,125
9,000
4,150
5,000
2,400
1,100
800
575
600
460
520
Total Solids
Gng/1)
7,440
74,200
49,300
28,100
19,600
8,930
10,700
5,630
3,100
2,280
1,620
1,740
1,440
1,230
pH
(units)
8.0
13.1
13.2
12.9
12.8
12.6
12.7
12.5
12.2
12.0
11.7
11.5
11.5
11.2
Suspended
Solids
(mg/D
2,010
5,040
6,320
1,900
1,510
690
2,420
910
640
420
380
300
270
580
25
-------
CO
JJ
T-l
e
Suspended
Solids
_ 8,000
_ 6,000
4,000
I
CO
•a
T3
ai
1
a
CO
3
, 2,000
FIGURE 5
VARIATION OF pH, AND SUSPENDED SOLIDS WITH WASHING OPERATION
FOR A 364 KG LOAD OF PRINT WIPERS
-------
100,000
TOG
80,000
i
u
"g
cd
at
•o
O
CO
CO
4J
O
H
60,000
40,000
20,000
FIGURE
VARIATION OF TOTAL SOLIDS AND TOG WITH WASHING OPERATION
FOR A 364 KG LOAD OF PRINT WIPERS
-------
TABLE 8
VARIATION OF WASTEWATER QUALITY FOR
MACHINE WIPERS WITH WASHING OPERATION
S3
00
Operation
Flush
Suds
Carryover
1 Rinse
2 Rinse
3 Rinse
4 Rinse
5 Rinse
6 Rinse
7 Rinse
8 Rinse
9 Rinse
Dye
10 Rinse
TOC
(mg/1)
18,000
43,500
30,000
13,900
4,000
2,000
850
730
470
810
236
136
288
194
Total
Solids Grease
(mg/1) (mg/.ll
51,087 18,000
864175
80,725
38,746
13,031
8,649
3,368
2,261
1,240
1,233
818
609
2,252
1,277 191
pH
(units)
8.3
13
13.1
12.7
12.5
12.3
12.0
11.6
11.2
10.6
10.4
10.1
9.9
9.7
Silica
as Si02
(mg/1)
7,200
5,000
3,000
920
660
*> n F
325
200
* t F
145
70
62
**rt
39
• j
44
30
BOD
(mg/1)
<100
7,960
6,825
4,500
900
380
Soluble
TOC
(ms/l)
23
?n
f.\j
13
-------
NJ
10
TABLE 9
VARIATION OF WASTEWATER QUALITY FOR
DUST MOPS WITH WASHING OPERATION
Operation
Flush
Suds
Carryover
1 Rinse
2 Rinse
3 Rinse
4 Rinse
5 Rinse
6 Rinse
Dye
7 Rinse
TOC
(mg/1)
910
12,500
15,250
9,800
5,950
4,920
2,150
1,460
850
650
304
Total
Solids
(mg/1)
3,731
40,543
50,591
32,740
18,940
10,541
6,236
3,291
2,201
3,686
1,987
PH
(units)
9.0
13.2
13.1
12.9
12.8
12.7
12.4
12.1
11.9
11.3
10.9
Suspended Soluble
Solids TOC
(mg/1) (mg/1)
1,420 520
2,990 775
685 69
-------
7,000
6,000
5,000
4,000
CN
c
•H
in
tn
ta
to
3,000
2,000 .
1,000 .
\o
00
er>
ed >
o o Pi
FIGURE 7
CARRYOVER OF SILICA IN SUCCEEDING WASH CYCLES
FOR A 364 KG LOAD OF MACHINE WIPERS
30
-------
A total of 12.1 kg or 27.5 pounds (Ibs) of silica as Si(>2 was measured
coming front this load of wipers. This compares with the addition of
approximately 3.6 kg (8 Ibs) of silica based on laundry supplier's data.
It may be noted that the water volumes of the different machine dumps
were not measured, but were determined by the level of water in the washing
machine, and may not be accurate. Likewise the addition of the required
amount of silica is dependent on the people loading the washing machine.
Some silica may have beeen present within the wipers themselves and
would also increase the amount measured.
Table 8 lists the data plotted in Figure 7 as well as some analyses -for
wastewater BOD. It is apparent that the BOD also varied significantly
with wash operation, but that after the carryover, it quickly decreases.
A load of print wipers laundered on this same day was checked for soluble
TOC for each machine discharge. It was found that 34.5% of the TOC
generated was soluble.
Table 10 presents the wastewater characteristics of various final rinses
sampled. In almost every instance, the water has a high TOC, total
solids, and suspended solids level. From the standpoint of TOC and
suspended solids, the last rinse has a water quality substantially poorer
than domestic sewage which may be expected to have a suspended solids
content of 250 mg/1 and a TOC of 100 mg/1. All final rinse samples of
the wipers and mops were visually dark and turbid. In some cases, the
final rinse samples from the print wipers were visually indistinguishable
from the first rinse samples. This raises the question of what quality
water is necessary for washing wipers in the laundering process. The
final rinse data indicate a high quality water may not be needed to
launder wipers, and demonstrates potential reuse benefits of reclaimed
water from the wastewater treatment system. As the pH and hexane soluble
content of final rinses of machine wipers and print wipers do not meet
the general standard of municipal sewer ordinances regarding discharges
(pH - 10.0, hexane solubles = 100 mg/1), the entire volume of wastewater
generated by these articles must be treated. In the wastewater reuse
portion of this study, it was hoped that the question of required reuse
quality would be resolved.
The data obtained from these individual washing operation samples was
also used to compute the mass of wastewater total solids and TOC
generated per 100 kgs of articles washed. The results of these computa-
tions are presented in Table 11. It may be noted that these results
include the mass of TOC and total solids that are added by the supplies.
The supplies generally add 2 to 5 kg of solids/100 kg of articles washed
dependent on the amount of soil present. More supplies are required for
heavier soil. The actual amount of solids contributed by the laundered
articles is then approximately 2 to 5 kg less per 100 kg of articles
washed than the results shown in Table 11-. Computations based on the
values in Table 11 and on actual laundry wash poundage, obtained on
days when composite samples of the sewer discharge were obtained,
predicted TOC and total solids twice as high as the composite sample
contained. Other samples obtained later in the project and utilizing
31
-------
1*1
TABLE 10
WASTEWATER QUALITY OF FINAL RINSES
FOR VARIOUS WASHED ARTICLES
Article Washed
Machine Wipers
Print Wipers, large
Print Wipers, small
Dust Mop
Dust Mop
Print Wipers, small
Machine Wipers
New Wipers
Print Wipers, large
PH
(units)
10.4
10.3
11.2
11.2
10.9
10.0
9.7
10.8
11.4
TOC
(mg/1)
400
200
520
768
304
236
194
676
260
Total
Solids
(mg/1)
1,660
660
1,230
2,910
1,990
640
1,280
2,700
1,180
Suspended
Solids
(mg/1)
445
272
580
750
685
440
—
—
__
Hexane
Soluble
(mg/1)
—
202
—
—
191
—
166
-------
TABLE 11
ESTIMATED WASTE LOAD QUANTITIES
FROM WASHING OPERATIONS
u>
Article Washed
Machine Wipers
Dust Mops
Print Wipers, small
New Wipers, small
Table Cloths
Kitchen Towels
Print Wipers, large
KGS TOC per
100 KGS Article Washed
23.9 - 44.6
12.0 - 13.0
18.4 - 33.9
4.3
0.9
2.3
29.3 - 41.9
KGS Total Solids per
100 KGS Article Washed
65.3 - 73.1
39.7 - 40.9
48.2 - 52.2
13.7
4.9
8.9
62.0 - 66.2
-------
average values for the TOG and total solids per 100 kgs articles
laundered predicted the composite sample TOC and total solids to within
10%. Thus the daily variability of the wastewater is demonstrated in
that the kilograms of soil washed out per unit mass of soiled article
varies significantly.
The small print wipers shown in Tables 10 and 11 measured 45.7 cm
by 47.5 cm (18"xl8") while the large ones measured 45.7 cm by 76.2 cm
(18"x30"). The large ones were used at large newspaper printing establish-
ments, and tended to produce more TOC and total solids per kg washed than
those used at smaller more varied printing plants. Whether the difference
in the contaminant values is due to the industry or the wiper size is
unknown. Similar analyses performed for linens demonstrated that they
contributed little to the waste load at this plant. It is apparent from
Table 11 that new unused wipers also contributed little to the wastewater
TOC and total solids. Approximately 902 of the wastewater TOC and total
solids come from the wipers and dust mops, with wipers contributing
significantly more solids and TOC per 100 kgs of articles laundered
than dust mops. Since larger amounts of wipers are washed per day than
either dust mops or linens, it is apparent that these are the main
sources of solids and TOC in the wastewater.
A series of BOD tests were performed on waste samples obtained for the
machine wiper washing cycle in Table 8. The tests of the last seven
rinses did not yield results because of improper dilutions and possibly
unacclimated BOD seed. However, they could be reasonably estimated from
the other data by plotting a curve similar to Figures 5 and 6. It was
found that approximately 4.9 kg of BOD/100 kg of wipers washed was
discharged during this operation. It is felt that this is low compared
to the high TOC values obtained and may be caused by the presence of
some bacteriologically toxic substances. Tests for suspended solids and
soluble TOC on small print wiper discharges indicates that 5.8 kgs of
suspended solids and 11.7 kgs of soluble TOC were dumped per 100 kgs of
articles laundered. Thus the suspended solids measured were 12% of the
total solids and the soluble TOC 34.5% of the total TOC for these print
wipers, indicating the presence of a large amount of dissolved inorganic
material. Average suspended solids analyses for various laundered articles
are compared for two rinses and a flush in Table 12. It may be seen that
the majority of the suspended solids come from machine wipers.
Considering all the data it appears that the majority of the suspended
solids are associated with the machine wipers and that a large portion
of the dissolved solids are associated with the print wipers.
From the foregoing analyses, it is evident that the waste discharge of
this laundry is highly variable in quality and strength, dependent on
what is being washed. The shop and printer's towels produce the most
contamination, and thus are the major problems in treating this waste-
water, as 60% to 70% of the wash poundage consists of these items.
34
-------
TABLE 12
SUSPENDED SOLIDS ANALYSES OF VARIOUS WASH OPERATIONS
OF VARIOUS LAUNDERED ARTICLES
In
Article Washed
Machine Wiper
Print Wiper, small
Dust Mop
New Wipers
Table Cloths
Kitchen Towels
Print Wipers, large
Average Suspended
Solids of Flush
(me/1)
Average Suspended
Solids of 4th Rinse
(tng/1)
7,700
1,690
1,415
605
1,160
2,410
3,780
5,110
2,030
2,290
— -
—
- —
1,550
Average Suspended
Solids of Last Rinse
455
510
718
240
272
-------
Thus, when designing an industrial laundry wastewater treatment system,
the factors of what items and how much of each item are laundered must
be known. Then with more data similar to that in Table 11, an approxi-
mation of the wastewater characteristics can be made for preliminary
studies. Likewise, the supplies and class of customers are important
in anticipating wastewater treatment problem areas. If the wash load
of the laundry is seasonal, or the wash load proportion changes radically
over a period of time (e.g., print wipers to linens), this must be known
prior to designing a wastewater treatment system. Addition of new
customers with different industrial operations than the normal clientele
may also affect a change in wastewater characteristics, thus rendering
a treatment system ineffective. It would not be necessary to go into
as much detail as was done here in characterizing the waste, but an
attempt should be made to identify the type and amount of soil associated
with each separate article laundered in order to determine what will
happen if the proportions of items change. This type of analysis can
also provide information on the degree of wastewater variability.
Laboratory Bench Scale Chemical Treatment and Solids Separation Tests
The significance of the wastewater variability was reflected in bench
scale chemical treatment and flotation tests conducted on both composite
and grab samples obtained from the laundry's sewer discharge. Chemical
tests in a preliminary feasibility study had indicated that alum and
acid treatment appeared to offer the most promising results for linen
laundry wastes (2). Consequently this was one of the chemical treatment
systems investigated for industrial laundry wastewater.
Investigations for alum chemical treatment characteristics were carried
out on three different wastewater samples of laundry discharge obtained
on March 3, 1971, March 15, 1971 and April 15, 1971. The chemical
characteristics of these three samples were presented in Table 3. The
optimum alura-sulfuric acid dosages were determined by jar tests, the
procedure for which may be found in Appendix B. Samples of wastewater
chemically treated at various dosages with various chemicals were subjected
to bench scale flotation tests to obtain design information as well as
to observe the effect of the chemical treatment.
Table 13 presents the results of several bench scale flotation tests
performed at various alum and acid dosages on the three samples. Jar
testing determined the chemical dosage range to use as well as the rapid
mix and flbcculation times. All mixing was done by hand, the rapid
mix by inverting the graduated cylinder several times and the flocculation
by a gentle swirling with the wrist. Developed recycle of actual waste-
water effluent was used as pressurized flow for all tests. It was
determined that the best results were achieved by adding the acid first,
then the alum, and then the polyelectrolyte, a nonionic one, with complete
mixing in between each chemical addition. The flocculation period
36
-------
TABLE 13
RESULTS OF BENCH SCALE FLOTATION TESTS
USING ACID AND ALUM CHEMICAL TREATMENT
Test No.
Chemical Treatment Sample Date
H2S04 (mg/1)
A12(S04)3-18H20 (mg/1)
Purifloc Nil (mg/1)
Rapid Mix Time, min.
Flocculation Time, min.
(mpm)
Recycle Rate, %
Rise Rate, meters/min.
Detention Time, min.
Scum Volume, 1/1000 1
Sludge Volume. 1/1000 1
Effluent:
pH
Suspended Solids, mg/1
Total Solids, mg/1
Volatile Total Solids, mg/1
TOC, mg/1
Silica, mg/1 as Si02
Conductivity, ymhos/cm
Sulfate, mg/1 as 804
Magnesium, mg/1 as CaCOj
Grease, mg/1
Percent Reduction in:
Suspended Solids
Total Solids
Total Volatile Solids
TOC
1
3/16
1270
2000
2
0.2
1.5
50.0
0.30
8
105
none
5.1
3
3750
405
115
460
3600
2000
15
27
99.9
37
88
94.8
2
3/16
1270
2000
0
0.2
1.5
50.0
0.15
8
97
3
5.1
37
3780
505
135
— —
—
—
11
— -
98.3
37
85
93.9
3
3/16
1760
800
2
0.2
1.5
50. n
0.52
8
60
trace
5.3
48
3980
473
140
— —
3700
2500
10
— —
97.7
34
86
93.6
4
3/16
1960
450
2
0.2
2
50. n
0.52
8
45
trace
5.1
25
4200
524
152
—
3900
2400
12
—
98.8
30
84
93.1
5
3/3
980
2000
2
0.1
1.5
50.0
0.24
8
120
trace
4.5
12
•3660
524
363
405
—
—
—
™
99.0
47
77
92
6
3/3
845
2500
2
0.1
1.5
50.0
0.21
8
150
trace
4.1
24
3976
560
395
450
—
--
—
•••••
99.0
42
76
91
7
4/15
2940
750
2
0.1
5.0
50.0
0.43
10
83
trace
3.8
105
6000
934
664
170
—
— —
__
•b^
95.6
19
61
78
8
4/15
2940
500
2
0.1
5,0
50.0
0.10
10
45
trace
3.85
112
6209
932
674
180
—
—
— *
tniim
95.3
16
61
78
-------
started with the last chemical addition. The effluent from these tests,
though low in suspended solids, was turbid and colored. The effluent
quality, deteriorated as the alum dosage was reduced for the March 16
sample. This is best reflected by the effluent volatile total solids and
effluent TOC data. The effluent suspended solids data in the table may
be misleading since the untreated colloidal solids remaining in suspension
are not measured as suspended solids. However, the scum volumes generated
were considerably lower at low alum dosages.
Combinations of calcium chloride, sulfuric acid and alum were also tried.
The addition of calcium chloride prior to treatment with acid and alum did
not substantially reduce the amounts of acid or alum needed nor did it
raise the pH at which the best floe was formed.
The addition of a polyelectrolyte to the waste treated with alum and acid
or with calcium chloride was found to improve the rate of floe formation
and the effluent clarity. No attempt was made to find the minimum amount
needed, since the cost of the polyelectrolyte is small compared to the
cost of the inorganic chemicals needed. Comparison of Tests 1 and 2 shows
that the polyelectrolyte helped in the removal of suspended material.
Considerable hanging floe developed without the use of the polyelectrolyte.
An average of 98% of the suspended solids were removed in all tests along
with an average of 89% of the TOC, indicating an association of the
organic material with the suspended matter. In all cases, the rise rates
were fairly rapid.
The sample obtained on April 15 did not demonstrate the same results as the
previous samples, as both effluent TOC and suspended solids Increased
considerably at alum dosages of 500 to 750 mg/1. This testing demonstrated
considerable variability inherent in the optimum chemical dosages, and that
jar tests would have to be run in the field each day. The percentage
reduction of contaminants occurring however, still looked impressive.
Concern was expressed as to the effect of the wastewater discharge varia-
bility on this type of chemical treatment. Consequently, grab samples
of the wastewater going to the sewer were obtained at 10 minute intervals
on April 15, 1971. All samples were analyzed for alkalinity. Bench
scale chemical treatment tests were performed on many of the samples to
determine the effect of wastewater variability on the chemical treatment
process.
Figure 8 demonstrates the observed variability in the wastewater pH
measured in the field as a function of time. It can be seen that the
effluent pH was always between 11.0 and 13.5 Though this appears to be a
small variation, one should keep in mind that this represents a variation
of two orders of magnitude in pH since it is a logarithmic function.
The grab samples obtained were tested for chemical treatability
using alum and sulfuric acid. It was initially anticipated that this
chemical treatment could be performed within a small pH range utilizing
a constant alum dosage. By controlling the influent pH to the treatment
system with an acid feeder stroked by a pH meter, a constant pH could
38
-------
14
13
c
•3
i 12
OJ
vO
11
10
JL
J.
JL
50
100 150 200 250
Time After First Sample - minutes
300
350
FIGURE 8
VARIATION OF LAUNDRY SEWER DISCHARGE pH WITH TIME ON APRIL 15, 1971
-------
be maintained. Then by providing a constant alum feed, the wastewater
could then be effectively coagulated. It was demonstrated, however, that
neither pH nor alum dosage could be maintained at a constant level and
provide consistently good chemical treatment. A summary of optimum
alum-acid chemical treatment-conditions for several of the grab samples
In Table 14 Illustrates this point. For samples with alkallnities near
500 mg/1, an initial pH of 9.0 is required for effective alum treatment.
For samples higher in alkalinity, a pH of 4.0 to 4.6 is required. For
some samples having alkalinities greater than 500 mg/1, alum dosages near
2000 mg/1 are required. Thus it is apparent that, because the acid-alum
treatment is very pH sensitive and the required alum dosage is highly
variable, it was felt that consistent chemical treatment would be exceed-
ingly difficult, and would require an equalization basin of inordinate
size considering the space limitations of the laundry. Likewise the dally
variability of the wastewater would require that jar tests be run to
determine optimum chemical dosage. It was felt that this would be
unrealistic in terms of the project objectives since it would take the
good part of an operating day to obtain a representative sample from an
equalization process, and would require laundries to hire a relatively
skilled treatment plant operator to run these tests and observe the system.
It appeared that alum-sulfuric acid coagulation was too sensitive to the
characteristics of the wastewater to easily and consistently provide good
chemical treatment. Therefore, sulfuric acid-alum treatment was rejected
for treating this particular wastewater.
Calcium chloride was also evaluated as the flocculating chemical. It was
found that 2000 to 2500 mg/1 CaCl2*2H20 would provide consistent treatment
with no pH adjustment in 85% of the April 15 grab samples tested. The
floe formed was stable. Those wastewater samples with alkalinities of
1000 to 6000 mg/1 were all treated effectively, as demonstrated in
Figure 9. A least squares regression line is drawn through the data.
Bench scale flotation tests were also performed using calcium chloride
and an anionic polyelectrolyte as coagulants. Calcium chloride is a
known emulsion breaker, so its usage for this wastewater was indicated.
Table 15 presents the results obtained on the previous mentioned waste-
water samples. The resulting effluent was a pale orange reflecting
the usage of a red dye for the shop towels. However, the subnatant was
clearer than the acid-alum treatment had been, even though it appeared
the suspended solids were slightly higher. (See tests 1 to 4 in Table 13.)
The rise rates were about the same, while the sludge volume was consider-
ably increased. Scum handling is discussed later in the report. The
effluent TOC obtained was approximately the same for each chemical system.
Nalco 7720, a cationic emulsion-breaker, was also evaluated as a treatment
chemical. It was found that 30 mg/1 of this chemical utilized in
conjunction with 100 mg/1 bentonlte clay at a pH of 3.8 to 4.8 would
provide fairly consistent treatment for the April 15 composite sample.
However, the floe formed by the emulsion breaker was very fragile.
40
-------
TABLE 14
OPTIMUM ALUM AND SULFURIC ACID DOSAGES FOR
WASTEWATER EFFLUENT GRAB SAMPLES OF
APRIL 15, 1971
Sample
NoT
1
2
10
17
19
24
27
31
34
36
37
39
Alkalinity
as CaC03
mR/1
2500
1570
528
970
1472
1440
580
6150
4690
1500
2200
1020
H2S04 Dosage
mg/1
2450
2150
196
1080
1670
1375
245
6860
4800
980
2150
785
pH
After
Acid
Addition
5.3
5.6
8.8
4.1
4.4
4.8
9.1
4.55
4.2
8.6
4.6
6.7
Optimum
Alum
Dosage
mR/1
500
500
500
500
750
500
500
500
2000
2000
500
750
Final
PH
4.6
5.0
7.2
3.9
4.3
4.3
5.8
4.5
3.9
5.0
4.2
5.1
-------
10,000
5,000
F
8
a
>
_
•-
-
r
<
-
-
I
1,000
50
100
Low pH
poor treatability
Correla
Coefficient = 0.886
Good
Treatability
tion
High pH
Poor T
abllltv
11 12 13
pH
FIGURE 9
CORRELATION OF pH AND WASTEWATER ALKALINITY FOR GRAB SAMPLES OF APRIL 15, 1971
•42
-------
TABLE 15
RESULTS OF BENCH SCALE FLOTATION TESTS
USING CALCIUM CHLORIDE CHEMICAL TREATMENT
w
Test No.
Date of Sample
Chemical Treatment
CaCl2*H20, mg/1
Purifloc A23,mg/l
Gallon 3000-A. mg/1
Mix Time, mln
Flocculation Time, min
Recycle Rate, %
Rise Rate, mpm
Detention Time, mln
Scum Volume, 1/1000 1
Sludfie Volume. 1/1000 1
Effluent:
pH
Suspended Solids, mg/1
Total Solids, mg/1
Volatile Total Solids, mg/1
TOC, mg/1
Silica, rag/1 as S102
Magnesium, mg/1
Ca, mg/1
Percent Reduction in:
Suspended Solids
Total Solids
Volatile Total Solids
TOC
1
3/3
2000
2
0.1
1.0
50
0.52
8
120
trace
11.5
79
2830
644
540
160
96
59
80
88
2
3/16
2500
2
0.2
1.5
50
0.15
8
270
none
11.6
32
3030
533
142
60
1
98.5
50
84
93.5
3
3/16
2000
2
0.2
1.5
50
0.30
8
180
trace
11.8
65
2920
600
192
96.9
51
82
91.3
4
4/15
1500
1
5.0
0.5
50
0.12
8
248
none
12.1
59
4038
1318
613
43
31
97.4
46
64
80
-------
Table 16 lists bench scale flotation test results for this type
chemical treatment. Hanging floe developed in the test, and the sub-
natant was very turbid, as in the acid alum testing. The scum volume
generated was low but the rise rate was slower than the other chemicals.
The emulsion breaker would not work without the addition of bentonite.
A longer flocculation time was also required. The effluent quality
measurements made were similar to that of the other tests in Tables 13
and 15.
Tests were also performed to compare the results of the alum and acid,
calcium chloride, and Nalco 7720 emulsion breaking systems on a more
direct basis. Consequently, samples obtained from each dump of the
entire washing cycle of various articles on the March 16 trip to the
laundry were composited for chemical treatment tests to determine which
individual articles yielded wastewater that was the most difficult to
treat. Each dump was composited in proportion to the amount of water
utilized in the washing cycle. Chemical treatment tests utilizing alum,
Nalco 7720, and calcium chloride were performed. The results of these
tests are presented in Table 17. All treatment evaluations listed in
the table are qualitative in nature.
From Table 17 it is self evident that the calcium chloride treatment
provided the most consistent results of all the chemicals tested. The
most difficult items to treat were the print wipers. From the above
studies, it was determined that calcium chloride was the best coagulant
that could be utilized for the demonstration system for chemical treatment
of the laundry discharge. It was also evident that the calcium chloride
was more tolerant of wastewater variability.
Many other chemicals were also tried in combination with many polymers
of different varieties, but none were found to be effective. Table 18
lists other chemicals that were tried and rejected.
Laboratory Bench Scale Filtration Testing
The composite sample obtained on April 15, 1971 was a 200 1 (55 gal.) bar-
rel of Wastewater. This sample was divided into two equal volumes with
each individual volume subjected to flotation utilizing the pressure
tank of a prototype flotation unit. Two separate flotations were per-
formed in a 189 I (50 gal.)-.plastic container to obtain scum for Buchner
funnel testing and vacuum filter leaf testing. One flotation was
performed utilizing 30 mg/1 Nalco 7720 after adjustment of the pH of
the wastewater to 4.2, 100 mg/1 bentonite clay, and 2 mg/1 Purifloc
Nil; and the other utilizing 2000 mg/1 CaCl^ • 21^0 and 2 mg/1 Purifloc
A-23. Tap water was used for recycle with the pH adjusted to that of
the chemically treated wastewater. Fifty percent recycle was used.
Approximately 20 1 (5 gal.) of scum were obtained from each test. Solids
analyses for the two scums are presented in Table 19. In both instances,
the flotation scum had a suspended solids content suitable for vacuum
filtration.
44
-------
TABLE 16
RESULTS OF BENCH FLOTATION TESTING PERFORMED
ON THE APRIL 15 COMPOSITE SAMPLE USING AN EMULSION BREAKER
H2S04 Added, mg/1 2940
pH after H2S04 4.1
Nalco 7720, mg/1 30
Ben ton! te, mg/1 100
Mix Time, min. 0.1
Flocculation Time, min 5
Recycle Rate, % 50
Rise Rate, mpm 0.08
Detention Time, min. 10
Scum Volume, 1/1000 1 68
Sludge Volume, 1/1000 1 0
Effluent:
pH 4.1
Suspended Solids, mg/1 44
Total Solids, mg/1 5722
Volatile Total Solids, mg/1 713
TOC, mg/1 571
Ca, rag/1 24
Si, mg/1 as Si02 170
% Reduction:
Suspended Solids 98.0
Total Solids 36
TOC 81
Volatile Total Solids 80
45
-------
TABLE 17
CHEMICAL TREATABILITY CHARACTERISTICS OF
INDIVIDUAL LAUNDERED ARTICLES UTILIZING THREE
DIFFERENT CHEMICAL SYSTEMS
Articles Washed
Large print wiper
used at newspapers
Small print wipers
Dust Mops
Machine Wipers
pH-Alkalinity
pH - 12.3
alk - 3577 mg/1
as CaC03
pH - 12.6
alk - 6076 mg/1
as CaCC«3
pH - 12.5
alk - 4557 mg/1
as CaC03
pH - 12.3
alk - 3185 mg/1
as CaC03
Nalco 7720 -
Bentonite Clay
initial pH - 3.9
100 mg/1 7720
+300 mg/1 bentonite
-»very fine floe
treatment - poor
initial pH » 3.9
+200 mg/1 bentonite
-*»fine floe
treatment - poor
initial pH - 7.0
30 mg/1 7720+
100 mg/1 bentonite
treatment - fair
initial pH - 4.6
30 rag/1 7720+
600 mg/1 bentonite
treatment - fair
Alum - Acid
(b)
initial pH 6.5
5000 mg/1 alum
to pH 3.95-^no floe
treatment - poor
initial pH - 4.6
2000 mg/1 alum
at pH 4.3
treatment - poor
CaCl2'2H20
(c)
initial pH - 5.6
2000 mg/1 alum
-••small floe at pH 5.1
treatment - fair
^ Composite samples of individual washing machine dumps for each article.
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TABLE 18
CHEMICALS THAT WOULD NOT TREAT
LAUNDRY WASTEWATER EFFECTIVELY
Alum and Sulfuric Acid
Ferric Sulfate and Sulfuric Acid
Magnesium Chloride and Calgon 3000A
Nonionic Emulsion Breakers
Anionic Emulsion Breakers
Cationlc Emulsion Breakers
Ferric Chloride and Sulfuric Acid
Ferric Chloride
Lime
47
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TABLE 19
SCUM CHARACTERISTICS FROM TWO TYPES OF
CHEMICAL TREATMENT FLOTATION BENCH SCALE TESTING
00
Chemicals Emulsion Breaker CaC 12*2^0
Total Solids, mg/1 38,400 61,100
Volatile Total Solids, rag/1 38,157
Suspended Solids, mg/1 18,800 55,600
-------
The procedure utilized for the Buchner funnel and leaf testing may be
found in Appendix B. Conditioning of the emulsion breaker scum
demonstrated that lime, ferric chloride, and an anionic polyelectrolyte
would provide a large visual floe. However, specific resistances, a
measure of the ability of the sludge cake to impede water flow through
the cake's pore structure, of 1.2 to 1.5 x 10 sec2/pm were obtained with
chemical dosages of 10% to 30% lime, 6% to 10% ferric chloride, and 0.05%
to 0.1% anionic polyelectrolyte on a dry solids basis.
Other combinations of lime alone and ferric chloride alone did not
appreciably lower these values. This compared with specific resistances
of 2 to 5 x 10' sec^/gm for ferric chloride conditioned digested sludge
that was filterable (9). The specific resistance was thus relatively
high for this sludge after chemical conditioning. Likewise the sludge
was exceedingly compressible, and the cake pore structure readily
collapsed near the end of each test creating a gelatinous cake and
thus indicating possible vacuum filter cloth blinding problems. Blinding
is here defined as the plugging of vacuum filter cloth pore openings
with sludge solids such that that portion of the cloth can no longer
pass water. This reinforced the rejection of Nalco 7720 for usage
in the wastewater treatment system.
Buchner funnel testing of raw calcium chloride scum indicated specific
resistances of 5.0 x 107 sec /gm. Utilizing conditioning chemicals of
lime, ferric chloride and various poly electrolytes not only did not
improve this value, but in most instances increased the specific
resistance. Consequently, it was decided no conditioning chemicals were
needed to vacuum filter this sludge. Consequently, filter leaf tests
were performed on the remaining scum without chemical conditioning for
the purpose of filter sizing, filter medium selection, filtrate quality
analyses, filter operating conditions, and filter cake solids
determinations.
Fourteen different filter leaf tests were performed on the remaining
sludge sample utilizing four different filter cloths whose properties
are listed in Table 20. The monofilament was found to be unsuitable
due to the presence of cloth fibers wrapping around the large openings
and blinding the cloth. These, could not be washed out. The cloth
selected from the remaining three was number two of Table 20, because
it had better discharge characteristics than either cloth 3 or 4 and
provided better filtrate quality. The discharge from the cloth was
excellent and it manifested no blinding problems during the testing.
The final tests were performed utilizing this cloth. Because of cake
cracking at 18% cake solids, no higher cake solids could be achieved.
The cake formed was greasy, but was 6 millimeters (rim) or 0.25" thick and
discharged readily. Therefore, a vacuum filter of the characteristics
outlined in Table 21 was recommended. The size was based on a supply
of 272.4 kg (600 Ibs) of dry solids an hour, or on a chemically treated
suspended solids concentration of 6,000 mg/1 at 757 1pm (200 gal./min -
gpm). Previous testing showed this to be a reasonably expected solids
concentration.
49
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TABLE 20
FILTER CLOTHS USED IN BENCH
SCALE FILTER LEAF TESTS
No.
Type
Permeability Thread
cmm/sq m Count Weave
1 Polypropylene Monofilament
2 Polypropylene Multifllament
3 Polypropylene Multifilament
4 Polypropylene Multifilament
too open
2.97
4.07
0.70
56x39 7/1 satin
58x46 2/2 twill
58x32 1/1 plain
50
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TABLE 21
RECOMMENDED VACUUM FILTER CHARACTERISTICS AND
OPERATING CONDITIONS OBTAINED FROM LEAF TESTS CONDUCTED ON
FLOTATION SCUM
Filter Size
Media
Pick-Up Time
Dry Time
Submergence
Cycle Time
Expected Yield
Expected Cake Solids
1.52 m (5 feet - ft) diameter
x 2.13 m (7 ft)
1PP 129-6009800 of Mero & Company
40 seconds
80 seconds
25% surface area wetted
2.6 minutes
26.4 kg/sq m/hr
18.0%
51
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Another large sample of laundry vastewater was obtained on July ]5,
1971. This too was subjected to flotation, as the first barrel of
wastewater had been, utilizing 2000 mg/1 CaCl2*2H20 and 2 me/1 Purifloc
A-23 with 50% recycle. The scum generated had a total solids content
of 4.24%. Leaf tests performed at the same conditions as Table 21
provided filter yields of 39.2 kg dry solids per square meter per hour
(kg/sq m/hr) (8.0 Ibs dry solids per sq ft per hr) at cake solids of 11%.
A one minute filter cycle time could also be utilized to achieve yields
of 65.9 kg dry solids per sq meter per hour (13.5 Ibs dry solids per sq
foot per hour). The cake cracked at 11% solids. This same problem
occurred for the first sample that was leaf tested at 18% cake solids.
These tests demonstrated that the filtration rate of the sludge could
be expected to vary markedly from day to day, and that cake cracking
is characteristics of the sludge. These tests confirmed the earlier
recommendations for the vacuum filter.
The raw wastewater and flotation effluent of the above test was subjected
to heavy metal analysis, as it now came to our attention that heavy
metals could be a problem at many industrial laundries. Many sewer
ordinances prohibit the discharge of heavy metals. Table 22 presents
the results of these analyses. From Table 22 it can be seen that heavy
metals are present in the waste at concentrations considerably greater
than trace amounts, and that the heavy metals are reduced significantly
by treatment with calcium chloride and flotation. This is most likely
due to the high pH of the waste resulting in most of the metals being
present as colloidal hydroxides. As suspended material these metals are
then effectively removed. If a chemical treatment system was utilized
that resulted in an operating pH near neutrality, many of these metals
would solubilize and not be removed. This is another point in favor of
calcium chloride as the primary flocculant, as it works effectively at
a high pH. Because of this, the area of heavy metal removal was monitored
throughout the rest of the project. Lead and mercury were the large
problems at this laundry under the Chicago Sewer Ordinance.
Because of the nature of the solids remaining in the wastewater, it was
evident that they would be readily amenable to diatomaceous earth (DE)
filtration. The solids were very flocculant. A flotation effluent of
about 100 mg/1 suspended solids was expected. Bench scale testing of a
mixed media filter consisting of 29 cm anthracite, 22 cm sand, and
7 cm of gravel demonstrated only 50% removal of the flotation effluent
residual suspended solids at a hydraulic loading of 167 liters per
minute per square meter (Ipm/sq m) or 4.1 gal. per minute per sq ft
(gpra/sq ft). There was no visual difference between the influent and
effluent. Diatomaceous earth filtration of the same wastewater removed
almost 100% of the suspended material and produced an effluent having a
high degree of clarity though orange in color. It was felt this was
required if the wastewater effluent was to be reused in this study.
Because diatomaceous earth filtration produced such good results, it
was decided to perform bench scale leaf tests utilizing a diatomaceous
52
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TABLE 22
REMOVAL OF HEAVY METALS BY CALCIUM CHLORIDE
TREATMENT AND BENCH SCALE FLOTATION OF INDUSTRIAL
LAUNDRY WASTEWATER
Metal
Iron
Lead
Cadmium
Copper
Zinc
Chromium
Cobalt
Mercury
Influent
Concentration
mg/1
11.5
7.3
0.06
2.3
2.08
1.66
0.23
0.05
Effuent
Concentration
mg/.l
1.9
0.3
0.01
1.2
0.29
0.5
0.10
0.03
Percent
Removal
84
96
48
86
70,
58
40
40
53
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earth filter on chemically treated raw industrial laundry wastewater.
In this way, the flotation tank would be bypassed so that space could
be conserved. The raw wastewater sample utilized was the Hay 20, 1971
sample of Table 3. A 2.54 cm (1 inch) filter leaf precoat of Johns-
Manville Hy Flo Supercell was utilized at varying test conditions to
get an idea of process feasibility. The support septum was the same
cloth selected for the vacuum filter. The bench scale test procedure
utilized may be found in Appendix B.
Table 23 presents the results of this testing. It is apparent that
excellent filtrate quality was achieved. The cake solids content
measured was in the range of 40% to 50%. Thus sludge volumes could be
reduced threefold to fourfold as compared to the flotation, vacuum
filtration system. However, due to the amount of diatomaceous earth
required, the. operating cost would be exceedingly high. The cost for
diatomaceous earth-alone at 17.6 cents per kg (8 cents per pound) would
be between $0.30 and $0.48 per cu m ($1.15 and $1.83/1000 gal.) of
raw wastewater plus chemical costs, sludge handling costs, and capital
investment. The diatomaceous earth usage rate was calculated by assuming
a 0.013 cm (0.005 in.) filter aid cut, a final cake thickness of 0.65 cm
(0.25 in.), and a diatomaceous earch packed density of 340.2 kgs/cu m
(21 Ibs/cu ft). Consequently, though the process looked feasible and
provided water of a high effluent quality, the concept was not pursued.
Investigations of sludge incineration were also pursued and found to be
uneconomical. This study may be found in Appendix D.
RECOMMENDED FLOW SHEET
On the basis of the foregoing test work, it was decided that calcium
chloride chemical treatment, dissolved-air flotation, diatomaceous
earth filtration of flotation effluent, and vacuum filtration of the
flotation scum would be able to treat the wastewater. On the basis of
the test results with the calcium chloride, it was decided that no
additional wastewater equalization would be required at this time.
Figure 10 represents a flow diagram of the recommended treatment scheme.
The filtrate from the vacuum filter was recycled to the rapid mix
chamber, because it was felt that the filtrate would not be of high
enough quality to discharge. The flotation effluent is neutralized with
sulfuric acid prior to discharge to lower the pH to 10.0. The other
process elements shown in the flow sheet are self-explanatory.
The design criteria utilized for the wastewater treatment system are
presented in Table 24. All of these were developed from the bench
scale treatment testing presented previously. It was felt that these
design criteria would provide a system with enough flexibility to meet
the project objectives. The expected solids generation data were also
based on the bench scale testing. The DE filter was sized later with
the aid of the filter manufacturer, and is reported on elsewhere.
54
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TABLE 23
ROTARY PRECOAT VACUUM FILTER
TEST RESULTS OF CHEMICALLY TREATED
INDUSTRIAL LAUNDRY WASTEWATER*
Test #1 Test #2 Test #3 Test
Pick-up Time, sec. 60 30 45 25
Dry Time, sec. 30 15 49 20
Cycle Time, min. 2121
% Drum Submergence 50 50 37.5 37.5
Filtrate Volume, ml 277 160 240 153
Filtration Rate, 1pm/sq n 14.6 16.9 12.8 16.3
D.E. Thickness Required, cm 6.3 7.6 6.3 7.6
Filter Area Required, sq m 51.6 44.6 59.4 46.5
Kgs DE/day 706 1130 814 1080
Filtrate Suspended Solids, mg/1 6738
DE Cost, V-/GU m 30 48 35 46
* Chemical treatment - 2,000 mg/1 CaCl2*2H20, 2 mg/1 purifloc A-23
55
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Flocculation
Rapid
Mix
I
Pressurized
in
ON
CaCl.
I
Flow
Vacuum
Filter
Polyelectrolyte
Vacuum Filtrate
Final Effluent
Sludge
Cake
Storage
Ultimate Disposal
of Sludge
FIGURE 10
INDUSTRIAL LAUNDRY WASTEWATER TREATttETrT FLOW SHEET
-------
TABLE, 24
BENCH SCALE DESIGN CRITERIA FOR THE
INDUSTRIAL LAUNDRY WASTEWATER TREATMENT SYSTEM
Item
Chemical Treatment
Waste Characteristics
Flotation
Vacuum Filtration
1500 mg/1 CaCl2
2 mg/1 Purifloc A-23
Rapid Mix - 1 to 3 min.
Flocculation Time - 5 to 8 min.
Nine Hour Day
r
pH range - 11.7 to 13.0
6000 mg/1 suspended solids after
chemical addition
Recycle - 50%
Rise Rate - 0.15 mpm - 152 Ipm/sq m
Flow Rate - 757 1pm
150 1 scum/1000 1 wastewater
Detention Time - 15 min.
Scum Solids -4%
1 Kgs dry solids - 2,450/day
Metric tons wet solids - 12.25/day
Cubic meters of sludge - 13.8
No Chemical Conditioning
10.2 sq m of filter .
Mero & Co. 1PP 129-6009800 Filter Cloth
57
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This completed the initial laundry survey and preliminary system design.
The rest of this report is devoted to the sizing and operation of the
recommended 757 1/min (200 gpm) treatment system on various types of
laundry wastewaters.
FINAL SYSTEM DESIGN
At the beginning of the full scale design phase of this project, it was
realized that floor area was going to be a definite problem in fitting in
and designing a 757 1/min (200 gpm) demonstration laundry wastewater treatment
system. The available area as shown in Figure 1 measured about 2.13 m
(7 feet) wide by 12.8 ra (42 feet) long with a maximum height of 3.2 m
(10.5 feet). This area was to accommodate the flotation, vacuum
filtration, and flocculation facilities. The diatomaceous earth filter
was to be placed beside the vacuum filter shown at the widest end of the
treatment system location outline of Figure 1. This occupied an area
of about 1.5 m (5 ft) by 4.25 m (14 ft) itncluding all tanks and pumps.
Because the wastewater treatment system was located right on the laundry
washroom floor, floor area was at a premium in this critical work area.
Consequently, the design of the demonstration system had to be made to
fit in this area. The overhead monorail s;ystera used to transport dirty
laundry completely surrounded the wastewafier treatment area thus making
it physically impossible to build outside of this space even if it was
desirable. All pumps, accessories, instrumentation and chemical
storage was to be in this same area. The sludge front the vacuum filter
was to be conveyed outside the building, over an alley, and into an
open topped dumpster located in a fenced-in enclosure.
Therefore the design philosophy was to me.et the bench scale design
criteria as closely as possible, utilizing the available volume.
Flotation System Design
Because laboratory testing had showed that the chemically treated floe
formed was exceedingly tough and readily filterable, the most critical
portion of the system was the flotation solids separator rather than
the flocculation and vacuum filtration facilities. Therefore, this
piece of equipment was given priority in the allocation of the floor
area. The dissolved air flotation basin was based on the criteria
utilized by the American Petroleum Institute (API) (10). The major
design parameters are overflow rate, detention time, horizontal
velocity and depth to width ratio.
The basic principle of dissolved air flo tation is to produce extremely
small air bubbles (<100u) which can be attached to the particulate
matter in a wastewater and cause flotation and removal of the particulate
matter. To provide these fine air bubbles a liquid stream is mixed with
air under pressure. The pressure is th(»n released through a weir type
diaphragm valve to form the bubbles. Tltie bubble laden stream is then
58
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mixed with the remaining wastewater to be clarified in a contained mixing
zone within the flotation tank. This mixing zone has a detention time
of approximately 90 seconds. The bubbles attach to the solids in this
mixing zone. The bubble formation system is termed the pressurized flow
system. 'The source of pressurized flow was the flotation effluent.
Because of the possible presence of a significant amount of solids in the
pressurized flow stream, a pressure tank without packing material was
utilized. This avoided the potential clogging problems associated with
a, pressure tank packed with some form of tower packing to increase the
air water interface.
The following discussion will delineate the process steps occurring in
the flotation tank. Flotation effluent water is pumped into the pressure
tank. Air is mixed with the water at the inlet to the pressure tank.
The water level in the tank is controlled by a liquid level float switch.
A slight excess of air is always added. If the water level becomes too
low the air stream is vented to atmosphere to allow the water level to
rise. There is a deflector baffle in the tank which spreads the incoming
water and promotes a large air water interface for good air solution.
The pressure in the tank is controlled by an air operated weir valve;
this valve provides the proper back pressure as well as the required
shearing action to form the small bubbles. This valve is controlled by
a pneumatic controller. Once the pressure has been released and the
bubbles formed, the bubble laden stream is mixed with the remainder of
the raw wastewater flow. A 90 second mixing chamber is provided in the
tank prior to entering the flotation zone. This allows time for bubble/
solid attachment. Once the pressurized stream and remaining raw waste
have been mixed, they enter the flotation zone of the tark where separa-
tion occurs. A skimming system skims the floated scum into one scum
trough located at the inlet end of the tank, which conveys the scum to
a vacuum filter.
The following set of design criteria were utilized:
flow rate 757 1pm (200 gpm)
hydraulic loading H* Ipm/sq m (28 gpm/sq ft)
horizontal velocity 0.68 mpm (2.23 ft/mln)
pressurized flow rate 378 1pm (100 gpm)
operating pressure 2.81 kg/sq cm (40 psi)
detention time 10 minutes
depth to width ratio 0.5
The effective dimensions of the flotation tank were 5.36 m (17.6 ft)
long by 1.82 m (6 ft) wide by 0.91 m (3 ft) deep. The outside dimensions
of the tank were 1.37 m (4.5 ft) deep by 6.33 m (20.8 ft) long by 1.83 m
(6 ft) wide. The width was fixed by the treatment system area, and the
depth limited by the need of having room under the flotation tank for
pumps and chemicals. It would have been desirable to make the tank
larger to increase the detention time, but this was not feasible. Thus
59
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the detention time was 5 minutes less than desirable for the design
flow rate.
Vacuum Filtration System Design
The size of the vacuum filter was selected from the bench scale testing
to be 1.52 m (5 ft) in diameter by 2.13 m (7 ft) long. Consequently
a rotary belt, continuously washed filter of this size was purchased
from Amatek Inc. They also supplied the filter cloth belt, Amatek No.
WNX-F4EO-KM8, which was a nylon belt with properties very similar to the
one specified, but was no longer available. The cloth was a heavy spun
staple with a 130 x 66 thread count, a weight of 391 gm/sq m (12.8 oz/
sq yd) anrl a 7/1 satin weave. This cloth was identical in visual
appearance to the specified cloth. City water was sprayed on the cloth
to clean it on both sides.
Vacuum filtration is a solids dewatering process utilized for sludge
volume reduction. In the process, the sludge flows into a vat within
which rotates a cylinder with a plastic grid supporting the cloth filtra-
tion medium. As the cylinder rotates into the vat, a vacuum is applied
drawing liquid through the cloth and retaining the sludge solids on the
cloth. The total time one point on the drum is submerged in sludge is
termed the sludge pickup time. The cylinder continues rotating out of
the sludge vat still under vacuum such that the deposited solids are
further dewatered. In the final step, the vacuum is released and a semi-
dry solid is discharged from a variable speed driven roller. The time
from the vacuum release to when the sludge rotates out of the sludge is
termed the sludge dry time. Thus the process is continuous as long as
there is sludge in the vat.
The filtrate or separated liquid goes to a receiver tank which is under
vacuum from a 20 horsepower (hp) Bingham vacuum pump, sized for 8.50 cubic
meter/min (cmm) of air. The liquid filtrate is pumped back to the rapid
mix tank at a rate of up to 151 1pm (40 gpm) by a 3 hp La Hour centri-
fugal pump. The sludge was conveyed from the vacuum filter by a Moyno
bridge breaker progressive cavitating filter cake pump rated at 45 1pm
(12 gpm) and 3 hp. A Badger totalizing oscillating piston water meter
is on the filtrate line to measure the volume of filtrate generated.
The filter drum and discharge roller were driven by Reeves variable speed
drives. The sludge level in the filter vat, often referred to as drum
submergence, was controlled by a bubbler and a weir type diaphragm valve
located on the sludge inlet line. Thus the sludge level could be
maintained constant so that the filter vat would not overflow, and the
sludge pickup time and consequently cake thickness is maintained constant.
This is important because if the pickup time is too long, the cake will
be so thick it will slough off the filter as it rotates out of the
filter vat; and if the pickup time is too short, the filter will produce
such a thin cake, it will not discharge. A thin cake is a form of
filter blinding. Thus, as long as enough sludge is available, the
60
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optimum pickup time is maintained. Sludge was skimmed from the flotation
tank into a 220 1 (58 gal.) tank directly behind the perforated baffle.
The discharge from this tank flowed by gravity to the vacuum filter. This
was the line controlled by the diaphragm valve.
Diatomaceous Earth Filter System Design
Nine DE filter manufacturers were contacted in order to select the most
economical and workable filtration system. A DE filter capable of
handling the following wastewater characteristics was asked for:
suspended solids 100 mg/1
total solids 5,000 mg/1
temperature 120°F
grease 50 mg/1
pH 11.5 to 12.0
solid size 1.6 to 5.0 y
The particulate size range was determined from a bench scale flotation
effluent sample by a DE filter manufacturer.
The filtration elements or septurns are coated with a layer of diatoma-
ceous earth, a naturally occurring sedimentary rock consisting of
millions of dead aquatic plants known as diatoms. Deposits of this
siliceous material are found in California. These deposits are quarried,
crushed, dried, calcined, and air classified into different grades.
The final product is a mass of diatom skeletons and fragments of skeletons
ranging in size from 5 to 50 microns. This material is exceedingly
porous and adsorptive. Thus it is capable of removing small solids
and oils.
After the septums are coated with diatomaceous earth, the process
liquor is fed to the filter. Depending upon the suspended solids
content of the liquid, a body feed is or is not required. Body feed
is the addition of diatomaceous earth to the process liquor after the
precoat. This builds up a layer of diatomaceous earth with the suspended
solids and prevents the filter from clogging up quickly. It also
provides more surface area for the filtration. After the pressure
differential across the filter builds up to a predetermined level, 3.5
to 5.3 kg/sq cm, (50 to 75 pounds per square inch - psi) the filtration
is stopped, and the liquid flow reversed to remove the diatomaceous
earth and removed solids. This reverse flow, at a rate of 40.71 to
81.5 Ipm/sq m (1 to 2 gpm/sq ft) of filter, lasts for 1 to 2 minutes
and is collected in an adjacent tank. Then the filter is precoated again
and the filtration restarted.
With the responses from the inquiries to the DE filter manufacturers
and with the aid of a Johns-Manvi11e Corp. representative, the following
DE filter design criteria were developed for this application:
61
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filter area 27.9 sq m (300.2 sq ft)
flow rate 607 to 757 1pm (160 to 200 gpm)
precoat 0.5 kg/sq ra (0.10 Ib/sq ft)
body feed 4 parts DE to 1 part suspended solids
DE required Hyflow Super Cel
DE size 50% <11 y
The filter selected was a Keene Model 610.-E-328 pressure filter with a
total surface area of 30.5 sq m (328 sq ft) with filtration elements
consisting of polypropylene septum supports while the septum itself was
a polypropylene cloth bag. This was the most economical filter of all
those offered. The filter was sized to hold 0.52 cu m (18.5 cu ft) of
filter cake. The filter was to be backwashed at a rate of 19 I/sec
(300 gpm) with the Environmental Sciences Division designing the precoat
and body feed tanks. Two 946 1 (250 gal.) tanks were provided so that a
precoat and body feed DE concentration of 40 to 60 gm/1 could be
maintained. The slurry was kept in suspension by a 1/3 hp, 1750 rpm
Cleveland mixer. After precoating, both 946 1 (250 gal.) tanks were to
be utilized for body feed, whereas only one tank was needed for
precoating. The filter was precoated by a Durco Mark II centrifugal
pump rated at 568 1/m (150 gpm) at 18.3 ra (60 ft) of head. The body
feed was metered by a B.I.F. Industries Model 1731-30-0917 diaphragm
metering pump with a right angle gear drive.
Figure 11 is a sketch of the final diatomaceous earth filtration system
showing the plumbing between the different components of the system.
The direction of flow of the precoat cycle, backwash cycle, and forward
filtration are shown on the diagram. The filter backwash was directed
into the heat exchange pit.
Design of Supporting Systems
The appurtenant equipment and tasks necessary to provide a functional
demonstration system included site preparation, selection of the neces-
sary flow metering equipment, and design of suitable electrical and
pneumatic control systems. The site preparation included moving two
washing machines from the treatment system area, providing concrete
pads for the equipment, and filling in an existing water channel with
concrete.
Bids for the erection, plumbing, and electrical work were obtained by
laundry personnel.
The instrumentation includes two venturi flow meters with recorders and
integrator totalizers to measure both inlet and outlet flow rates. It
was hoped that the difference of these two measurements would be the
scum volume generated each day. A flow through pH meter with strip
chart recorder was also Installed in the system to both measure and
control effluent pH. The output of the pH meter went to a pneumatic
62
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Effluent
946 1
Body Feed
Tank
946 1
Precoat
Tank
Body Feed
Pump
Drain
FIGURE 11
DIATOMACEOUS EARTH FILTER SCHEMATIC DIAGRAM
Raw Flow
_. Precoat Flow
__._._._ Backwash Flow
-------
transducer which converted the recorder's 4-20 milliamp signal to
a 0.21 to 1.05 kg/sq cm (3 to 15 psi) air signal. This air pressure
positioned a diaphragm valve on the discharge side of the acid feed
pump. The air signal received was proportional to the difference in the
desired pH (setpoint) and the measured pH. In this way, effluent pH
would always meet the sewer code. Any excess acid pumped was recycled
hack into the acid container by bypassing the valve. An indicating
mercury manometer connected to a sharp edged orifice plate measured
pressurized flow. Various pressure gages were included in the air
flotation system to keep track of the air solution process.
Figure 12 presents a process and instrumentation diagram for the system
and shows all system controls. The untreated wastewater flow comes from
the discharge side of the heat exchanger pump discharging to the sewer
shown in the upper right hand corner of the diagram. The raw flow then
goes to a rapid mix and flocculator chamber of the dimensions (1.8 x 1.8
x 3.4 meters (6 x 6 x 11 ft) deep. A movable baffle alloxjs the detention
time of each section to be varied. The raw flow to this process is
recorded. Dissolved calcium chloride was added to either the pipeline or
the rapid mix section of this tank and the polyelectrolyte to the
flocculator section. Mixing and flocculation were achieved with either
sparged air or three variable speed Cleveland mixers which could gently
agitate the whole tank. The odd size of the chemical treatment facilities
was also determined by the available floor area. Because of the shape of
the flocculator tank, conventional turbine or paddle wheel flocculators
could not be used. -The tank was made 'extraordinarily deep in order to
get the desired mixing time. It was felt the length of mixing for this
particular wastewater was more important than the type of mixing, as
laboratory testing had demonstrated that the floe was tough and not
easily sheared. It also reformed readily. There was a total of 10
minutes detention time available in this tank.
From the flocculator, the chemically treated raw flow enters the
flotation tank where solids separation occurs. The operation and
control of this system was described previously. The flotation effluent
then overflows a weir into a small storage tank, where it is either
pumped to the sewer through the diatomaceous earth bypass or to the DE
filter. An air operated weir type diaphragm valve on the discharge side
of the diatomaceous earth pressurization or transfer pump was controlled by
a bubbler level controller in the effluent storage tank. This was to
insure that the transfer pump never ran dry and to control the flow to
the DE filter. Theoretically, as the pressure drop built up in the DE
filter, the flow to the filter would decrease causing a liquid level
rise in the storage tank. The bubbler sensing this would cause the
diaphragm valve to open wider to bring the level in the effluent storage
tank down to the set point. The level controller was the same type
used in the vacuum filter vat.
64
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FIGURE 12 PROCESS AND INSTRUMENTATION DIAGRAM
FOB LAUNDRV WASH IRtAIMENI SYSTEM
-------
From the transfer pump, the flow could go to the DE filter, operated
as described previously. A differential pressure sensor on the DE filter
sounds an alarm when the setpoint is exceeded to indicate when backwashing
is required. During a backwash the flow to the filter is reversed, and
the transfer pump discharge used to backwash. The backwash water is
directed to the heat exchanger pit. While the filter is being precoated
again, the transfer pump discharge is directed to the DE bypass and to
the sewer.
The heat exchanger pump feeding the system was controlled by a float
switch in the heat exchanger pit. The demand for hot water in the
laundrv was also tied into this pump. At periods of low level in this
pit or no heat demand (durinp. lunch break) tMs pump would shut off.
In order to prevent the wastewater treatment system from having to be
shut down and started up frequently, whenever the pump shut off, two
Grinnel diaphragm valves were actuated by a solenoid valve connected to
plant air to redirect final effluent to the effluent storage tank. In
this way, positive pressure was maintained on the PE filter to prevent
cake loss and the pressurized flow was always kept running. When the
pump started again, the flow was redirected to the sewer. When all
motor starters and other switches were in the automatic position, this
control scheme was in operation. Manual overrides were provided for all
systems.
Two adjustable timers controlled the on time and the off time of the
skimmers and bottom sludge scrapers. Automatic samplers were provided
for the raw wastewater, vacuum filtrate, flotation effluent, and diato-
maceous earth effluent. These were controlled by two adjustable timers
such that the sampling interval and the length of sample could be
controlled. The samplers were air driven valves, which opened when the
first timer timed out and closed when the second timer timed out. In
this way, true composite samples could be obtained from all four points.
This sequencing was also stopped when the heat exchanger pump turned off.
The scum from the flotation unit was directed to the vacuum filter which
operated as described previously. Vacuum level could be controlled by
two butterfly valves on the pickup and dry vacuum lines. The scum could
also be directed to a sludge conditioning tank with a side entering mixer
and three minute detention time, if sludge conditioning should be required
due to changes in sludge characteristics. Filtered sludge was pumped
to a storage location outside the plant for ultimate disposal by a
scavenging service.
The chemical feed system selected for this wastewater treatment installa-
tion consisted of two 473 1 (125 gal.) polyelectrolyte tanks, one
1,892 1 (500 gal.) calcium chloride tank, and a Chemcon triple headed
metering chemical pump. Calcium chloride at a concentration of 500 gm/1
of solution can be fed at rates of 0-4 1pm (Orl gpm). The polyelectrolyte
at a concentration of 0.2% can be fed at rates up to 1.0 1pm & gpm) as can
66
-------
concentrated sulfuric acid. The acid was pumped from the drum in which
it was supplied to the pH control system. Another double headed chemical
metering pump was available for sludge conditioning if this should be
required. All plumbing connections were made with 1.27 cm (0.5 in.)
plastic tubing.
The design drawings for the system were completed in October of 1971.
The tanks and system components were contracted for fabrication or
ordered by mid-November of the same year. The contractors to perform the
installation of the unit were selected by January of 1972 and all
erection, plumbing and electrical work completed in April of that year.
Costs for the demonstration system are presented in Appendix £•
OPERATIONAL METHODS AND TEST PLAN
The demonstration system was put into operation in May of 1972, The unit
was to be tested to determine the effect of various process variables on
effluent quality, as these related to local sewer ordinances. Variables
requiring investigation are presented in Table 25. It was hoped that
each of these variables could be run at several levels of operation so
that their effect on effluent quality could be determined. It was
desirable during the testing of the unit to firmly establish the follow-
ing items for each type of laundry waste listed in Table 25!
operating costs
sludge volume production
optimum operating conditions
effect of laundry mix on treatment process
It was also part of the original EPA grant that the feasibility of reusing
renovated wastewater in the laundering process be investigated. This
was to be done by utilizing treatment system effluent directly in a 364 kg
(800 Ib) washing machine bringing it to the desired level on a batch
basis for each washing operation. The water is then heated to the
desired temperature with steam prior to commencing"the laundering cycle.
This is repeated for each wash operation. Samples of each dump are then
taken to be compared to samples taken from each washing machine dump of
a control batch of articles washed with softened city water. Laundry
personnel then inspected each batch of washed items and evaluated their
cleanliness. It was hoped that those laundering operations the waste-
water effluent could be reused in could be identified as well as the
rate of buildup of dissolved solids in the rinsed water. Likewise, it
was hoped to determine if this dissolved solids buildup would have a
detrimental effect on the wastewater treatment process.
During the evaluation of the system, it was to be operated four days per
week at the specified overflow rate, chemical dosage, and other variable
levels. Composite samples of influent, flotation effluent, and vacuum
filtrate were taken automatically and analyzed for the constituents
67
-------
TABLE 25
PROCESS VARIABLES TO BE INVESTIGATED
FOR LAUNDRY WASTEV/ATER TREATMENT
Laundry Mix
Industrial - wipers, dust mops
Uniforms - shirts, pants, coveralls
Linens - tablecloths, towels, etc.
Diapers
Chemical Treatment
Dosage
Point of addi tion
Flocculation time
Rapid mix time
Flotation
Overflow rate
Skimming Cycle
Pressurized Flow
Diatomaceous Earth Filtration
DE grade
Body feed rate
Hydraulic Loading
Pressure buildup - length of filter run
Vacuum Filtration
Pick-up time
Cycle time
Vacuum level
68
-------
listed in Table 26 at the interval specified. The vacuum filtrate samples
would have only solids analyses performed on them. Grab samples of scum
were composited manually. Grab samples of any process stream were taken
during any system upset or unusual condition and analyzed for those
constituents deemed important.
The vacuum filter was sampled manually with a sharp edged circular cutter
of approximately 0.0093 sq m (0.1 sq ft) area. Normally 3 cake samples of this
size were taken at both ends and the center of the drum to equalize the
variation in cake solids and thickness normally found across the filter
drum. Several samples of this type were taken at regular intervals and
averaged to represent the response variable values at a particular set of
operating conditions. Following any change in operating conditions, at
least 5 drum revolutions were allowed to occur before any cake samples
were taken as representative of those operating conditions. After
sampling, the cake was placed in an aluminum tin and weighed immediately.
The vacuum filter was operated so that it would just keep pace with the
sludge production of the flotation system, so that 'the filter could be
operated continuously. A vacuum filter is generally not amenable to
sporadic operation. Due to our limited sludge storage, sludge had to be
filtered almost as soon as it was produced.
No rigid test schedule was followed so that when unanticipated important
parameters manifested themselves, they could be properly investigated.
Likewise, the nature and variability of the wastewater made it evident
that certain operating conditions would have to be developed during the
progress of the project as experience with the treatment system was
gained. Thus it was felt that this test plan would accomplish the
project objectives set out at the beginning of this report.
It was desirable to. test the four different types of laundry wastewater
listed in Table 25 because of the very different characteristics of all
four wastewaters and because each one made up a significant portion of
the laundry industry in general. It was felt that if the treatment
system was designed for the strongest, and presumably the most difficult
to treat wastewater, it would be flexible enough to handle linen, diaper,
and uniform laundry wastewater which would be expected to be weaker.
These other wastewaters and the bench scale test work and design deci-
sions associated with them are presented later in this report.
69
-------
TABLE 26
LAUNDRY WASTEWATER ANALYSES TO BE
PERFORMED ON COMPOSITE SAMPLES
Parameter
BOD
TOC
Hexane Solubles
pH
Suspended and Volatile Suspended Solids
Total and Volatile Total Solids
Alkalinity
Ca 1 c i urn
Lead
Mercury
Cadm i urn
Zinc
Copper
Chromium
Iron
Nickel
Si 1 ica
Analysis Interval
weekly
daily
daily
dai ly
dai ly
dai ly
dai ly
weekly
weekly
weekly
weekly
weekly
weekly
weekly
weekly
weekly
weekly
70
-------
SECTION V
INDUSTRIAL LAUNDRY WASTEWATER TREATMENT SYSTEM OPERATION
INITIAL OPERATION AND DEBUGGING
The operation of the system was initially delayed due to the lack of a
permit from the City of Chicago to construct a sludge discharge line from
the laundry over an alley to the sludge dumpster site. Until this permit
could be received, it was not possible to operate the treatment unit and
remove sludge from the system, making evaluation of the operation fruitless.
During this time period, the system was operated wet with the scum generated
being drained to the heat exchanger pit, so that mechanical malfunctions or
process problems could be resolved prior to actual system operation. Some
of the problems that were corrected during this time period are listed
below.
Improper motor heater sizes on all motors
Misalignment of skimmer sprocket and chains
Additional skimmers added
Replacement of bolts in bottom scrapers
Plumbing modification to vacuum filter
Moved effluent flow meter
After performing the above tasks and many other minor ones, the system was
operated utilizing one cubic yard carts to collect the vacuum filtered
sludge. The unit could only be operated for short periods of time in this
manner due to the large quantities of sludge generated. Six runs were
performed in this manner to evaluate initial treatment results and to further
debug the wastewater treatment system. Wastewater samples were obtained
from four of the runs. Table 27 presents the basic operating conditions
for these four runs, while Table 28 reflects the performance of the vacuum
filter and Table 29 presents the wastewater analyses performed on the
composite samples obtained. The length of operation was limited by the
volume of sludge that could be processed.
It can be seen that the vacuum filter results varied significantly even
while operating at the same conditions. Cake solids varied between 10%
and 22Z. Likewise, filter yield also fluctuated significantly. Some of
this variability in solids could be due to volatilization of some greases
71
-------
TABLE 27
SYSTEM OPERATING CONDITIONS
FOR RUNS OF JULY AND AUGUST, 1972
8/8 8/8
Parameter Run 1 Run 2 8/9 7/19
Length of Run, hours
CaCl2 Dosage, rag/1
A-23 Dosage, mg/1
Recycle Ratio, %
Raw Flow, 1pm
Overflow Rate, Ipm/sq m
Vacuum Filter Cycle Time, rain.
Vacuum Level, cm Hg.
Avg. Pick Up Time, sec.
Sludge Flow Rate, 1pm
DE Filter Pressure Buildup, kg/sq
hr
DE Body Feed, rag/1
DE Grade
1.5
1860
1.8
80
473
85.5
3.25
50.8
40
15
cm/ —
1.5
1300
1.2
56
681
105.8
3.25
50.8
40
15
;;
MMi^HMV
2.9
1660
1.3
59
643
101.7
—
—
—
—
0.5
200
Hyflow
Super
Cell
•••I^HBB
3.25
1170
0.9
57
662
105.8
3-5.7
38.1-45.7
—
12.5
72
-------
TABLE 28
RESULTS OF VACUUM FILTER
OPERATION OF JULY AND AUGUST, 1972
Vacuum Pickup Cycle
Level Time Time
Date (cm Hg) (sec) (min)
7/13
7/13
7/18
7/19
7/19
7/19
7/19
8/8
8/8
8/8
8/8
8/8
25.4-
50.8
25.4- —
50.8
50.8-
63.5
38.1-
45.7
38.1-
45.7
38.1-
45.7
38.1-
45.7
50.8 40
50.8 40
50.8 40
50.8 40
50.8 51
3.25
3.25
5.7
3.0
3.0
5.7
5.7
3.25
3.25
3.25
3.25
4.16
Solids
Loading
(kg/sq m)
0.622
0.622
1.681
0.676
0.730
1.480
1.078
1.152
1.176
0.990
0.936
0.862
Yield
(kg/sq m/hr)
11.52
11.47
17.64
13.57
14.55
15.53
11.32
21.22
21.71
18.33
17.30
12.40
Cake Solids
Percent
14.02
21.90
18.62
14.85
15.18
16.60
12.61
10.12
18.76
14.01
12.79
20-65
73
-------
TABLE 29
INITIAL INDUSTRIAL WASTEWATER TREATMENT RESULTS
DE
-7—Raw Wastewater Flotation Effluent Eff. System % Removal
Analysis 7/19 8/8-1 8/8-2 8/9 7/T9 8/8-1 8/8-2 8/9 8/19 7/19 8/8-1 8/8-2 8/9
pH - units .12.2 11.8 11.8 11.8512.1511.6 11.5 11.511.45—
Total Solids, mg/1 6469 5042 5042 8649 4117 3704 3369 5694 5609 36.4 26.5 33.2 35.1
Suspended Solids, mg/1 1870 2096 2096 4950 385 99 H2 108 9 79.4 95.3 94.7 99.8
TOC, rag/1 4150 3200 3200 6300 700 490 620 440 320 83.1 84.7 80.6 94.9
Hexane Solubles, mg/1 5319 2121 2121 2805 215 23 60 146 17 96.0 97.1 98.9 99.4
Silica, rag/1 230 78 97.0
Mercury, ug/1 1.2 <0.5 18 98<0
Nickel, mg/1 1.0 0.30 0.20 80.0
Lead, mg/1 35.8 0.35 0.10 99.7
Chromium, mg/1 3.60 3.25 3.86 0
Cadmium, mg/1 0.60 0.03 0.03 95.0
Copper, mg/1 9.3 0.69 0.50 93.4
Iron, mg/1 126 2.4 2.4 9.81
-------
and oils when drying in the oven at 102°C. Likewise, since there is no
sludge blending or storage time available in the unit, the solids concen-
tration of the scum varied significantly with time. Scum solids concen-
trations of 3.3% to 9.0% were demonstrated on two of the days, and this
contributes to changing vacuum filter performance.
The initial vacuum filter yield, i.e., the kilograms of dry sludge solids
filtered on one square meter of cloth in one hour, was not as high as hoped
for. The cake solids obtained were about what was expected. The solids
loading presented in Table 28 is the mass of dry sludge solids filtered per
square meter of filter area, whereas the cycle time is the length of time
required for one drum revolution. Filter yield is calculated by multiply-
ing the solids loading by 60 over the cycle time. The moisture content
of the sludge is calculated as 100% minus the cake solids. It may be noted
that filter yields of only 12 to 20 kgs/sq m/hr (3 to 4 Ibs/sq ft/hr) were
obtained as against projected yields of 24 to 29 kg/sq m/hr (5 to 6 Ib/sq ft/
hr). The filter manifested no blinding problems duirng these operations, and
demonstrated that it was debugged.
The nature of the sludge caused difficulties in the sludge handling
facilities. After the sludge had been pumped by the Moyno cake pump, it
liquified. This made the sludge a liquid disposal problem, and as such
could not be handled in an open topped dumpster by an ordinary scavenger.
Since the sludge was a liquid, it could not be legally landfilled as a solid
waste. Consequently, haulers specializing in the disposal of liquid wastes
had to become the regular handlers of the wastewater treatment residue.
This caused a considerable increase in hauling cost; $11.75/cu m ($9.00/
cubic yard - cu yd) versus $3.20 cu m ($2.50 cu yd). All sludge generated
for the rest of this project was handled as a liquid waste. The location
of the laundry on the western side of Chicago limited the alternatives
for sludge handling at this site.
Table 29 demonstrates that the flotation unit was doing its job in removing
grease and solids as well as a good deal of organic matter. The effluent
quality obtained from these samples was excellent considering the raw
wastewater characteristics. It was not anticipated that the results would
be as good as the bench scale testing, due to the batch nature of this
type of test. The flotation tank produced an acceptable effluent operating
near the design conditions during these four runs, notably 1,500 mg/1 of
calcium chloride and a raw flow of 644 to 682 1pm (170-180 gpm). Waste-
water variation in characteristics did not appear to adversely affect the
chemical treatment.
The diatomaceous earth filter operation of August 9 was highly promising,
as the DE filter built up little pressure drop during the run indicating
the DE filter might need little DE to do an effective treatment job. The
clarity of the DE effluent was excellent as attested to by the 9 mg/1
suspended solids in the effluent. It is apparent the DE filter was an
excellent polishing step, and that it removed a residual of heavy metals.
75
-------
Table 29 lists the results of the August 9 heavy metals analyses and the
percentage removal of each contaminant. From this table, it is evident
that the treatment system was removing all contaminants under consideration
except for chromium. Evidently, no chromium was removed because it was
present in the hexavalent form. In order for chromium to be removed at a
high pH, it must be reduced to the trivalent form to be precipatated as a
hydroxide. The heavy metal removal demonstrated in the laboratory was
duplicated in the field.
Thus the initial operation of the industrial laundry wastewater treatment
system was very promising. Based on these results, it was felt that the
debugging of the system was completed.
WASTEWATER TREATMENT SYSTEM OPTIMIZATION
The permit for the sludge carrying pipe was received in August of 1972, so
that the sludge handling facilities were ready for full time operation in
September of that year. The open topped dumpster was replaced at this
time with a liquid tanker. The completion of this part of the system
allowed the actual test plan to commence. The first test was performed
on October 11, 1972 with the first full week of operation occurring during
the week of October 15. The basic operating parameter for these runs are
presented in Table 30. During these runs, the DE filter was utilized
only once.
Irrespective of the test conditions, it is apparent that the operation of
the flotation unit was unsatisfactory on all test days in terms of effluent
suspended solids and hexane solubles, as shown in Table 31. Of all the
test runs, the one at the lowest overflow rate provided the best results.
However, in no case were the effluent suspended solids, TOC, or hexane
solubles approaching the concentrations obtained in the bench scale testing
or the preliminary operation* Neither overflow rate or chemical dosage
appeared to affect the solids separation - an inconsistent result.
A severe vacuum filter cloth blinding problem now manifested itself also.
During the October 17 and 18 operations, filter blinding was a definite
problem. At times the filter cloth would produce a cake one half inch
thick and then suddenly not produce a cake thick enough to discharge.
When this occurs, the filter must be shut down and the cloth manually
cleaned, and if the problem is not rectified, the whole treatment system
must be shut down in order to get rid of the scum. It thus appeared that
some substance was coining through periodically causing poor filtration,
then disappearing and the filter recovering* Filter cake solids of 27Z
to 54Z were obtained with filter yields varying from 11.3 to 34.3 kgs/sq m/hr
(2.3 to 7.0 Ibs. dry solids/sq ft/hr). The scum total solids concentra-
tions were somewhat variable, but were generally near 5%. Some scum
samples that caused blinding contained 7.6% solids - a more than adequate
concentration to provide a thick cake. The scum concentration did not
correlate well with filter yield as it should have; as according to
filtration theory, the higher the solids concentration, the higher the
filter yield (11). Therefore, the filter blinding was not related to
inadequate scum solids concentration.
76
-------
TABLE 30
SYSTEM OPERATING CONDITIONS FOR OCTOBER 11 TO OCTOBER 20, 1972
Parameter
Length of Run
Avg. Raw Flow
% Recycle
CaCl2 Dosage -
A-23 Dosage -
Skimmer Speed
Overflow Rate
- hours
Rate - 1pm
- mg/1
n»g/l
- mpm*
- Ipm/sq m
10/11
5.0
568
80
2,100
1.5
0.60
102
10/17
3.8
719
53
1,550
0.9
0.46
110
10/18
3.0
814
4-6
—
0.5
0.46
118
10/19
5.1
341
111
1,355
1.3
0.46
73
10/20
4.3
795
48
2,040
0.5
0..46
118
* 5 minutes on and 5 minutes off.
77
-------
TABLE 31
WASTEWATER QUALITY FOR FIVE TEST DAYS
BETWEEN OCTOBER 11 AND OCTOBER 20, 1972
Operating Date
Analysis 10/11 10/17 10/18 10/19 10/20
Raw Wastewater
Total Solids - mg/1 6,068 4,230 6,217 5,996 6,662
Suspended Solids - mg/1 — 2,825 3,965 3,620 3,775
TOC - mg/1 — 3,200 3,120 3,260 4,200
Hexane Solubles - mg/1 — 2,600 3,363 3,418 3,756
pH - units 12.0 10.0 11.5 11.65 11.7
Silica - mg/1 as Si02 — 690 810 670 830
Flotation Effluent:
Total Solids - mg/1 4,541 3,891 4,736 5,033 6,670
Suspended Solids - mg/1 908 1,058 1,991 782 2,914
TOC - rag/1 -- 980 1,360 920 1,740
Hexane Solubles - mg/1 502 566 1,006 425 1,663
pit - units 11.4 9.9 10.6 11.6 10.9
Silica - mg/1 as Si02 — 55 72 16 43
Scun Concentration
Average Total Solids - % 6.9 1.7 8.6 8.4 5.2
Grease - 2 of Solids — 56 76 53
DE Filter Effluent:
Total Solids - mg/1 2,876
Suspended Solids - rag/1 48
TOC - mg/1 123
Hexane Solubles - rag/1 16
pll units , 10.65
Silica - mg/1 as Si02 108
78
-------
During the October 20 operation, a complete series of heavy metal analyses
were performed to determine if these contaminants were still being
removed by the treatment system in view of its poor performance.
Table 32 provides this data, and indicates a quite favorable DE effluent
quality in terms of heavy metals, in spite of the poor flotation effluent.
The very high suspended solids concentration of the flotation effluent
shortened the DE filter run considerably (0.5 hrs), but demonstrated that
the DE filter could produce very high effluent quality, even under adverse
conditions. Thus the DE filter could be expected to cover up system
upsets for short periods of time. However, better quality flotation
effluent was obviously required if DE usage was to be kept at a reasonable
cost. The high removal percentages of the heavy metals indicated that
they were still in a form amenable to solids separation, in spite of the
deterioration in the wastewater treatment system performance.
Analysis of grab samples of the various waste streams from the October 11
run demonstrated that the performance of the flotation process was erratic
even at the same operating conditions. This is aptly demonstrated by
Figure 13. This did not appear to be a function of raw wastewater solids
concentration, as shown in Figure 13. Because of the erratic and ineffi-
cient operation of the flotation unit, and the blinding of the vacuum
filter, work was halted to evaluate these problems. Until the root cause
of the filtration blinding problem was identified, no meaningful treatment
system performance data could be obtained.
Problem Identification
While evaluating the above problems, it appeared that there might have
been a change in the washing mix since the time the bench scale tests were
first performed in March of 1971. The basic change appeared to be in the
percentage of printer's towels now making up the wash load. Table 33
presents all the data available on this information at this time. The
general wash mix had not been extensively recorded up to this time, and
the laundry did not keep these records for long periods. It is evident
that the print wiper percentage was considerably greater during the
October 17, 1972 operation of the treatment system. It is not known if
this was due to an actual increase in the laundry's print wiper trade or
merely indicative of a large amount of variability in the proportion of
printer's towels washed that was not reflected in the initial sampling
program. The extent of the filter blinding problem, which had not
manifested itself before, suggested that some basic change had indeed
occurred.
Because of this observation, on November 10, 1972 the system was operated
while print wipers and machine wipers were laundered at different times.
From 7:30 am until 11:00 am, only printer's towels were laundered in the
industrial washing machines. From 11:00 am to 1:15 pin, only shop towels
were laundered in these same washing machines. The laundry maintained its
normal linen and dust mop wash schedule throughout the day. At 1:15 pm,
the laundry again began washing printer's towels.
79
-------
TABLE 32
REMOVAL OF HEAVY METAL CONTAMINANTS
BY THE INDUSTRIAL LAUNDRY WASTEWATER
TREATMENT SYSTEM ON OCTOBER 20, 1972
Analysis Raw Wastewater DE Effluent % Removal
Zinc-- mg/1 6.8 0.06 99.1
Chromium - mg/1 2.25 0.26 88.A
Lead - mg/1 16.5 0.20 98.8
Copper - mg/1 6.1 0.20 96.7
Cadmium - mg/1 0.45 0.1 77.8
Iron - mg/1 67 0.2 99.7
Nickel - mg/1 1 1 0
80
-------
oo
13.0
2500
S3
•a
JJ
o
H
§
O
11.0
7000
9.0
tH
E
*
w
7.0 5000
o
H
5.0
3.0
3000
Vacuum Filtrate Suspended Solids
Scum
Total
Solids
Raw Total Solids
Flotation
Effluent Suspended Solids
'2 3 ^
Hours After Start Up
FIGURE 13
VARIATION OF TREATMENT SYSTEM SOLIDS WITH TIME ON OCTOBER 11, 1972
2000
be
6
1500 '
us
•o
o
t/3
O
"S
1000 o>
500
-------
TABLE 33
PROPORTIONS OF PRINTER'S TOWELS IN THE
TOTAL LAUNDRY WASH VOLUME
Percentage Printer's Towels
Date in Total Wash Volume
3/3/71 0
3/15/71 17
5/19/71 25
5/20/71 29
10/17/72 42
82
-------
During this testing, the flotation system was operated at a flow rate of
567 1pm (150 gpm) and 67% recycle. The calcium chloride dosage was 2,200
mg/1 and the A-23 polyelectrolyte dosage was 2.3 mg/1. The vacuum filter
was operated at a cycle time of 4 to 5.5 minutes at a 15.2 cm (6 in.)
submergence and vacuum levels of 25.A to 63.5 cm Hg. Grab samples of
raw flow, scum, and flotation effluent were obtained every 15 minutes.
Buchner funnel tests were performed side by side with the vacuum filter
using different cloth media to determine if a different filter cloth would
overcome the blinding problem.
Figures 14 and 15 present the variation of influent and effluent wastewater
quality during the test day. The time periods when the laundering of each
item occurred are clearly marked. There were large variations in waste-
water quality for both print wipers and machine wipers. However, the
figures show no readily discernible differences in wastewater quality for
either of the two items. Consequently, the data ptesented in Figures 14
and 15 for the various grab samples were averaged for comparative purposes.
The results are shown in Table 34, and two apparent differences between
print wiper and machine wiper wastewater which manifest themselves are in
the areas of TOO and grease. The print wiper wastewater has a somewhat
higher grease and TOC content than the machine wiper wastewater. Scum
samples also indicated a higher suspended solids content for the scum
generated by the machine wipers than that generated by the print wiperst
This would indicate that print wipers produce a smaller amount of
filterable solids than machine wipers, and that the print wipers contain
more organic material than the machine wipers. These samples did not
demonstrate any dramatic differences in wastewater characteristics that
would account for any difference in sludge filterability.
During this test, the print wiper scum never was in a filterable condition.
The vacuum filter blinded immediately and discharged for a period of
only 0.5 hours out of the 3.5 hours available during the print wiper
laundering. After the print wiper testing, the print wiper scum was all
skimmed from the flotation unit and allowed to drain from the system prior
to sampling for the machine wiper wastewater. At 11:00 (200 minutes) when
the waste treatment operation was converted over to machine wiper waste-
water, the scum was Immediately dewaterable. At 1:15 (335 minutes), when
print wipers were again being washed, the filter blinding again manifested
itself.
The Buchner funnel tests performed with various cloth types side by side
.with the vacuum filter failed to provide any filter cloths that did not
blind. Even relatively open meshed branched monofilament polypropylene
cloths with air permeabilities of 17 to 42.5 cu m/sq m (200 to 500 cfm/
sq ft) blinded quickly on the print wiper scum. Neither open mesh mono-
filament or multifilaraent cloths of various characteristics could filter
the print wiper scum properly. This demonstrated that the filter blinding
was not a characteristics of the filter cloth, but of the print wiper sludge
since this sludge would not filter well on any filtration media tested.
83
-------
12 r-
11
n
u
•H
10
00
- 4000
00
E
3000 ,
u
c
H
2000
1000
200 300
Minutes after First Sample
FIGURE 14
VARIATION OF RAW AND EFFLUENT WASTEWATER pH and TOC WITH TIME
FOR NOVEMBER 10, 1972 WASTEWATER TREATMENT SYSTEM OPERATION
400
-------
10,ODO r
-, 12
8000 _
bO
B
0)
to
(0
0)
03
6000
oo
-a
-------
TABLE 34
AVERAGE CHARACTERISTICS OF
PRINT AND MACHINE WIPER WASTEWATER
FOR NOVEMBER 10, 1972
Parameter Print Wipers Machine Wiper
Raw TOC, mg/1 2,758 2,175
Effluent TOC, mg/1 536 760
Raw Grease, mg/1 2,932 2,379
Effluent Grease, mg/1 832 1,112
Effluent Suspended Solids, mg/1 309 654
Scum Total Solids, Z 8.05 8.98
Raw Total Solids, mg/1 6,048 5,964
Raw Volatile Total Solids, % 55.4 51.4
Effluent Suspended Volatile
Solids, Z 50.0 65.9
Scum Volatile Total
Solids, Z 67.4 68.4
Scum Suspended Solids, % 6.47 9.15
Scum Volatile Suspended
Solids, Z* 67.2 70.4
* Not run on all samples.
86
-------
Consequently, sludge samples of machine wiper and print wiper scum were
brought back to the laboratory for further testing. The sludge concen-
trations of these samples are presented in Table 35. The scum samples
obtained were then Buchner funnel tested to determine if there were
sludge conditioning methods that would increase the sludge filtration rate.
Buchner funnel testing was performed using a 9 cm funnel at a vacuum of
63.5 cm Hg to 68.6 cm Hg with a volume of 150 ml of sludge and No. 541
Whatman filter paper in all cases. With no modification in sludge
characteristics, the machine wiper sludge would yield 100 ml of filtrate
in 10 seconds while print wiper sludge provided 100 ml of filtrate in
240 seconds. Thus the difference in sludge filterability was evident.
Various polyelectrolytes were used in sludge conditioning tests to deter-
mine if this would improve the filtration rate of print wiper sludge.
Comparisons were made on the basis of filtration rate (sec/volume) rather
than specific resistance to facilitate more rapid testing.
r
Cationic and anionic polyelectrolytes utilized at different sludge pH's,
and in combination with ferric chloride, lime, and other metal salts
failed to improve print wiper sludge filterability. However, it was
found during these studies that pH adjustment of the sludge resulted in
increased filtration rates. Therefore, a series of experiments were
performed to determine sludge filtration rates at various pH values. This
was done for print wiper scum, machine wiper scum, and a blend of one
half of each of the scums by volume. Figure 16 presents these results
where the ordinate of Figure 16 is the time required to collect 75 ml of
filtrate during this test. It is evident from this figure that decreasing
pH resulted in increased filtration rates for all three sludges. The
optimum pH was found to be near 3.0.
Because of the good vacuum filtration dewatering characteristics of
machine wiper sludge, various blends of print wiper and machine wiper
sludges were filtered in the same manner as the previous testing. Figure 17
demonstrates that the combined sludge filtration rate decreases at an
increasing rate as more and more print wiper scum is added. This figure
indicates the need for sludge equalization. Due to the difficulty of
doing this at this laundry, equalization of the raw waste could be used to
accomplish the same result. This would help prevent slugs of material
emanating from the print wipers from reaching the vacuum filter.
Some of the print wiper scum was centrifuged in order to separate the
oily fraction from the solids. Buchner funnel testing of these solids
also demonstrated filter blinding properties. Filter blinding was then
not associated with the oily material.
It is common knowledge that metallic hydroxides do not filter well due to
their gelatinous nature (15). Consequently, both the machine and print
wiper scums were analyzed for heavy metals. Table 36 shows that there
were more heavy metals in the machine wiper scum than the print wiper
scum. The machine wiper scum filtered better than the print wiper scum,
thus tending to rule out th« hypothesis that metallic hydroxides were
87
-------
TABLE 35
CHEMICAL CHARACTERISTICS OF SCUMS
USED IN LABORATORY TESTING
Analysis
Total Solids - %
Volatile Total Solids - Z
Suspended Solids - %
Volatile Suspended Solids
Grease - %
Machine Wiper
Scum
10.7
7.2
9.2
6.0
7.4
Print Wiper
Scum
8.8
6.9
3.5
2.1
4.3
88
-------
100
80
0)
4J
PJ
•S 60
to
•a
8 40
OJ
20
Print wiper
Sludge
0
50% Blend of Both Scums
Machine Wiper^ Sludge
8
ie
12
Sludge pH
FIGURE 16
EFFECT OF SLUDGE pH ON FILTERABILITY
FOR THREE DIFFERENT MIXES OF LAUNDRY WASTEWATER
89
-------
250
0)
4J
i-H «
•rt
U.
«M 200
o
c
IB
"S 150
o
o
0)
100
50
100
20
80
40 60
% Print Wiper Scum
60 40
Machine Wiper Scum
80
20
100
0
FIGURE 17
EFFECT OF- VARIOUS RATIOS OF PRINT WIPER SCUM
AND MACHINE WIPER SCUM ON SCUM FILTERABILITY
90
-------
TABLE 36
HEAVY METAL CONTENT
OF TITO LAUNDRY FLOTATION SCUMS
Item
Lead - iag/1
Copper - mg/1
Zinc - mg/1
Iron - mg/1
Machine Uiper
Sludge
261
48
89
818
Print Wiper
Sludge
162
31
41
199
91
-------
the problem. However, there can be two types of metal present in the
wipers. Chips of lead and iron can be present in both types of wipers,
and would be measured in the heavy metal analyses. Likewise, some
metallic ions would be dissolved and would be precipitated as hydroxides
by the caustic of the wash formula. A particular metal can then be
present as its hydroxide1 or its un-ionized form. The metal chips would of
course filter quite well, whereas the metallic hydroxides would not.
Because no distinction could be made between the two forms of metal for
the two samples, the results of the testing were inconclusive. An attempt
to use heavy metal analysis of filtered acidified scum filtrate as a
measure of metallic hydroxides, i.e., assuming that metallic hydroxides
would dissolve quickly in acid and particulate metals would not, also
failed to show any significant differences between the two sludges.
Thus it was determined that the characteristics of the solids associated
with the print wiper wash water were the cause of the filter blinding
problems. An effort to identify the nature of the solids causing this
problem met with no success. Based on these results, it was concluded
that raw wastewater equalization was required, and that sludge neutraliza-
tion would increase the filtration rate. This led to replumbing of the
treatment system so that the linen storage pit could be used for equaliza-
tion and sulfuric acid could be fed into the sludge conditioning tank.
The equalization basin was mixed with air diffusers.
On December 20 a two hour run of the treatment system utilizing sludge
neutralization was performed in an attempt to improve the dewaterability
of the scum. The unit was initially operated for a period of one hour
without neutralization to establish base conditions and initial sludge
filterability characteristics. During this time, the cake thickness
decreased from about 3 mm (1/8") thickness which did discharge, to a very
thin 1.5 mm (1/16") thick cake which did not discharge at all. Operating
conditions for the system were kept constant at a flowrate of 719 1pm (190
gpm) 53% recycle, a poly electrolyte dosage of 1.5 mg/1 and a 2,000 rag/1
calcium chloride dosage. After one hour, concentrated sulfuric acid was
then metered into the scum conditioning tank and mixed with the floated
scum. The pH of the scum was monitored manually and the acid dosage
adjusted to allow a gradual decrease in pH from an untreated scum pH
of 11.4 to a low pH of 1.5.
Although the filter cake from the acid conditioned sludge darkened in
color, as was observed in laboratory tests, there was no apparent
increase in the filterability of the scum. Very little cake discharge
could be obtained even with the pH of the sludge adjusted.
Wastewater Equalization
Three wastewater treatment system runs were performed on January 9, 10, and
11, 1973 to evaluate the usage of the 32.2 cu m (8500 gal.) linen storage pit
as an equalization tank. During this operation, bench scale flotation,
chemical treatment, and leaf tests were performed to determine if the full
scale units performed in the same manner as the bench tests. The equalization
92
-------
pit was used for the January 10 and 11 testing, but not January 9. These
runs were merely performed to establish if the system could be operated
consistently using equalization, and as such, detailed laboratory analyses
were not performed on the samples obtained.
The basic operating conditions of the three runs are presented in Table 37.
The percentage print wipers reported is the percentage of the total
industrial wash poundage for that day that was print wipers. The percen-
tage filter blinded reported is the percentage of time during each day's
run that the filter cake failed to discharge from the filter drum. On
January 9, the unit was run as it has been in the past to establish a base
of comparison.
Total solids, suspended solids, and pH analyses were performed on raw
wastewater and effluent composite samples, as well as scum samples. On
January 9, seven grab samples were obtained, and each one analyzed
individually. The averages of these analyses are presented with the
analyses of the other composite samples for the runs in Table 38. In
general, it appears from Table 38 that the flotation unit performed about
the same each day. The only area where the change from no equalization to
the use of equalization clearly had an effect is delineated in Table 39,
showing that the changeover to equalization on January 10 had a beneficial
effect in that the filter never blinded at all.
During the January 9 run, with no equalization, and only 27% print wipers,
the filter blinded for one hour when print wiper sludge came through as
a slug, and then recovered. On January 10, when equalizing approximately
the same proportion of print wiper wastewater, the filter did not blind at
all. On January 11, the filter completely blinded even with equalization
when treating wastewater emanating from 40% print wipers. Though the scum
was thick enough to filter, 6.75% solids, the cake never discharged. This
demonstrated that the treatment unit cannot operate consistently without
equalization or when the proportion of printer's towels in the wash load
is much above 25%. Above this level, the solids present in the printer's
towels dominate the wastewater and cause filter blinding. There is then
too much print wiper wastewater present to dampen its adverse filtration
effects by equalization.
The cake solids and yield data presented in Table 39 is misleading as the
scum suspended solids vary significantly and consequently affect filter
performance. The variability of the scum solids makes it difficult to
compare vacuum filter results over any length of time. The basic criterion
of Importance for the vacuum filter is that it produce a relatively dry
cake at a rate compatible with the flotation unit. Thus the vacuum filter
does best when the wastewater is equalized with the printer's towels at
an acceptable proportion of the wash load.
The flotation, chemical treatment, and vacuum filter bench tests performed
provided results reasonably similar to the full scale operation. The
performance of the treatment system could be simulated by bench scale
93
-------
TABLE 37
WASTE TREATMENT SYSTEM OPERATING CONDITIONS
OF JANUARY 9 to 11, 1973
January 9
No
Parameter
CaCl2 dosage - rag /I
A-23 Dosage - mg/1
Ayg. Raw Flow - 1pm
Recycle - %
Length of Run - hours
Print Wiper - % of Industrial
Washload
Filtrate Flow - 1pm
%x>f Time Filter Blinded
Sludge Volume - 1/1000 1
raw waste
Surface Overflow Rate, Ipra/sq m
Equalization Time - hours
Equalization
1,690
1.5
473
80
5.62
27
44
18
42
85
1.13
January 1C
2,720
0,5
473
80
3.14
21.6
50
0
2<»
85
1.13
January 11
2,590
1.8
613
70
2.85
39.5
—
100
0
106
0.87
94
-------
TABLE 38
LABORATORY ANALYTICAL RESULTS
FOR JANUARY 9 to 11, 1973
Parameter
Scum Total Solids - %
Scum Suspended Solids - %
Raw pH - units
Effluent pll - units
Saw Total Solids - mg/1
Effluent Total Solids - mg/1
Raw Suspended Solids - mg/1
Effluent Suspended Solids - mg/1
Vacuum Filtrate pH - units
Vacuum Filtrate Total Solids - mg/1
Vacuum Filtrate Suspended Solids - mg/1
Effluent Grease - mg/1
5.33
4.10
11.05 to
11.75
11.1 to
11.85
9,279
3,933
2,705
510
384
4.13
2.60
11.6
H.I
5,770
3,678
2,285
795
11.9
5,340
580
312
7.78
6 75
—
8,564
4,817
3,916
516
271
95
-------
TABLE 39
VACUUM FILTER RESULTS FOR
VARIOUS RATIOS OF PRINTER'S TOWELS
% of Time Cake Solids Yield
% Printer's Towels Filter Blinded (% Dry Solids) (kgs/sq m/hr)
0% - no equalization 0% 48.23 30.5
21.6% - equalization 02 24.97 19.6
27.0% - no equalization 18% 26.85 29.1
39.5% - equalization 100% 0 0
100% - no equalization 100% 0 0
96
-------
testing for all unit processes, while performing them side by side with
the large system.
At this time, it was discerned that samples of flotation tank effluent
developed a considerable amount of afterfloc on standing overnight.
Afterfloc is the condition of precipitation or solids crystalization
occurring in a water. Thus the mechanism creates suspended material that
can be measured as suspended solids. The walls of glass sample containers
were observed to often be coated with a hard scale. Tests were conducted
in the laboratory to determine whether afterfloc and scale formation
might be reduced by increasing the amount of time between the addition of
calcium chloride and the polyelectrolyte. The present system operation
only allowed 1 to 2 minutes with the calcium chloride being added first,
and it was suspected that the polyelectrolyte may have been tying up the
calicum chloride floe too quickly, thus not allowing it to complete its
chemical reactions.
These tests were performed on the January 9, 1973 wastewater composite,
and the results are presented in Table 40.
It was found that increasing the length of time between chemical additions
could reduce afterfloc formation. Table 40 shows a definite increase in
turbidity and a reduction in silica concentration for the chemically
treated wastewater with increased time between chemical additions, thus
showing that silica is precipitating while the samples stand. It is known
that the calcium chloride precipitates the majority of the silicates
present in the wastewater (see Tables 28 and 29). From this testing, it
was evident that two minutes did not allow this reaction to go to
completion.
This phenomenon influenced all effluent suspended solids analyses up to
January 11, 1973 and could probably account for a significant portion of
the variability encountered in effluent suspended solids data to this date.
The samples often were several days old before analysis due to the distance
from the treatment site to the laboratory. Thus, afterfloc could cause
effluent suspended solids to appear much higher than they actually were
and account for the differences observed between the initial bench tests
and field performance.
Based on the operation of the industrial laundry wastewater treatment
system, the following changes in the treatment system were implemented:
1. Wastewater equalization of at least 1 hour required for consistent
treatment unit operation.
2. Only 25% of the industrial wash load could be printer's towels
during any treatment system operating day at any one time during
the day.
97
-------
TABLE 40
EFFECT OF VARYING TIME INTERVAL BETWEEN CALCIUM CHLORIDE ADDITION
AND POLYELECTROLYTE ADDITION ON AFTERFLOC FORMATION
FOR INDUSTRIAL LAUNDRY WASTEWATER
vO
'00
Time Interval
1/2 minute
1 minute
2 minutes
5 minutes
10 minutes
30 minutes
Turbidity. FTU
Initial* 8 hrs Later
Si, mg/1 as Si02
After 1 Day
33
48
23
21
17
13
40
48
34
32
20
14
Initial
60
54
43
47
34
24
Total
45
39
24
24
28
21
Supernatant
13
13
15
19
28
19
* Measured within 30 minutes of A-23 addition.
After Floe Formation
Formed within 5 min.
Formed within 15 min.
Formed after 1 hour
Formed within 8 hours
No after floe
No after floe
Test Procedure:
Results: 1.
2000 mg/1 CaCl2'2H20 added to waste, mixed 10 seconds, then allowed to stand 1/2,
1, 2, etc. minutes. 2 mg/1,A-23 was then added, the waste mixed 1 minute and the
floe allowed to settle. Hanging floe was removed by filtration through 541 paper.
The filtrate was then allowed to stand to observe afterfloc formation.
The initial turbidity readings for the 1/2 and 1 minute tests include afterfloc
already formed. After 8 hours, the afterfloc was very large and did not indicate
a high turbidity value.
Scale formed on the sample container walls during one day storage.
silica value also decreased.
The total
3. After the afterfloc settled, the supernatant contained significantly less silica
indicating that the afterfloc may be a calcium silicate material.
-------
3. Calcium chloride added to the equalization pit to provide the
necessary detention time between the addition of calcium chloride
and polyelectrolyte. The floe was tough enough that long
periods of agitation would not harm it.
OPERATING THE INDUSTRIAL LAUNDRY WASTE TREATMENT SYSTEM
WITH EQUALIZATION
The treatment system was operated from January 23, 1973 to January 31,
1973 utilizing industrial laundry wastewater generated when the printer's
towel wash load was kept below 20% of the total wash load to
prevent filter blinding problems. The equalization pit was used for all
runs, theoretically providing 53 minutes to 77 minutes equalization over
the rauge of flowrates studied. During this operation, the chemical dosage
and flotation tank overflow rate were varied to study the effect of these
two parameters. Composite samples of raw wastewater, flotation effluent,
vacuum filtrate, and diatomaceous earth effluent were obtained during each
run. Complete analyses including heavy metals were performed on all
samples. On two days, January 25 and 30, separate sample sets were
obtained when the diatomaceous earth filter was brought into the treatment
system after two hours of flotation tank operation. There was a set of
samples taken during the flotation tank operation and a set of separate
samples obtained after the diatomaceous earth filter came on line.
All operating data and wastewater analyses are reported in Tables C-4,
C-5, and C-6 of Appendix C for this test work. It will not be recorded
again in this section of the report, since this would be redundant. In
the data analysis which follows, two previous tests performed without
the additional equalization are also included, because they include a
complete set of heavy metal analyses. The data presented in the following
tables thus includes ten treatment system tests, two of which did not have
equalization. Only seven of the tests were performed utilizing the diato-
maceous earth filter.
The calcium chloride dosage and surface overflow rate were varied widely
during this testing to determine the effects of these parameters on
effluent quality. Likewise, information was obtained on sludge production
and operating skill required in order to obtain system operating costs.
The data obtained from the wastewater treatment system testing was erratic.
However, close observation of the results can provide insight into the
characteristics of industrial laundry wastewater treatment. Figure 18
demonstrates the variation of flotation effluent grease and suspended
solids with calcium chloride dosage and surface overflow rate respectively
for the data of Appendix C. The August 9 operation is not included in
this graph, because the measurement of the flow rate on this day was open
to some question. Likewise, the October 20 suspended solids analysis is
open to some question due to afterfloc formation. However, it was evident
that for these operating conditions that the effluent suspended solids
were much higher than normal. Therefore, this test day is included in
99
-------
Che graphs. From Figure 18 it appears that "000 mg/1 calcium chloride
is required to hreak the majority of the hexane soluble emulsion. Much
above this level, no additional hexane soluble removal is obtained.
Generally, 2,000 mg/1 calcium chloride provided a floe of very good
appearance, but the additional calcium chloride dosage may be needed to
obtain more hexane soluble removal in some cases. Flotation effluent
suspended solids were found to be very dependent on surface overflow rate,
increasing rapidly at overflow rates greater than 98 Ipm/sq.m (2.4 gpm/
sq ft). Operating much below 94 Ipm/sq n (2.3 gpm/sq ft) did not;.
enhance effluent suspended solids greatly. The optimum overflow rate of
the unit was then about 90 Ipm/sq m (2.2 gpm/sq ft). It is desirable to
keep the flotation effluent suspended solids low to prevent plugging of the
DE filter.
That the operation of the flotation system was improved by the system
changes is evident in Table 41 which presents some average flotation
effluent analyses of October and November, 1973 versus the January 23 to
January 31, 1973 flotation effluent analyses. Eight January samples are
compared to seven previous runs. The effluent hexlme solubles show an
improvement of 29% and the effluent suspended solids an improvement of 45%.
The change in the chemical addition points and equalization helped improve
effluent quality, even though the flotation effluent TOG stayed the same.
A least squares regression analysis on the January TOC and grease data
demonstrated a correlation coefficient of, 0.86 indicating that the
majority of the effluent TOC is related to hexane soluble material not
retained in the flotation tank. Any improvement in hexane soluble retention
would also considerably^lover the organic content of the wastewater. Since
DE filtration readily sorbs non-emulsified oils, it is to be expected that
the DE filtration step would considerably lower the TOC content of the
wastewater. As will be seen, this is what happened.
Other attempts at correlating the mass loading of the flotation unit,
overflow rate or calcium chloride dosage with other parameters did not
meet with success* This points out that the performance of the unit during
this testing was quite erratic, and could not be relied on to do an effec-
tive job 100% of the time. This also demonstrates the complexity of the
wastewater being dealt with, and the undoubtedly many intricate chemical
and physical phenomena associated with this wastewater. Because of this,
the performance of the industrial laundry wastewater treatment system will
be discussed on only a gross basis. .-
The erratic performance was also influenced by the equalization basin
initially, as a lot of material settled in the basin, and did not; show up
in the raw wastewater samples obtained going to the pit. Later the same
material was resuspended and appeared-at the inlet of the flotation tank.
Therefore, the raw wastewater sample po^t varied^during the course of
the January, 1973 testing to reflectjjthis trend. The first two s'ystem runs,
January 23 and 2Ut indicated very loW raw &rease and..suspended solids
analyses which led to concern that-a lot of material was settling-in the
equalization pit. Upon using the, pit ^entrance for the raw sample point
during the January 25 run, the suspended solids and grease immediately
increased. This demonstrated that the contents of the equalization pit
100
-------
1,500 -
CO
o>
i-t
•§
1,000 -
500 -
4J
g
«M
W
0
1,000
2,000
w 3,000 -
o
CO
"S 2,000
1
a
n
9
en
3 1,000 -
w
250
61
3,000 4,000
Dosage - mg/1
5,000
6,000
81.5 102 122.5
Surface Overflow Rate - lpm/sq m
FIGURE 18
EFFECT OF CALCIUM CHLORIDE DOSAGE ON FLOTATION
EFFLUENT GREASE AND SURFACE OVERFLOW RATE ON EFFLUENT SUSPENDED SOLIDS
101
-------
TABLE 41
CHANGES IN FLOTATION EFFLUENT QUALITY
WITH TREATMENT SYSTEM CHANGES
Effluent Suspended Solids, tng/1
Hexane Solubles, rag/1
TOG, mg/1
Oct. - Nov.
1972
1230
872
1049
January 1973
674
620
1077
102
-------
yere not mixed well enough. However, there was not time available to
rectify this problem before completion of the industrial laundry test work.
Table 42 presents the average removal of various industrial laundry waste-
water contaminants by the flotation unit and the diatomaceous earth filter.
Table 43 presents the average contaminant concentrations for these same
runs utilizing all the data presented in Table C-6 of Appendix C. Each
specific point on these two tables is the average of all numbers available
for that point. The number of observations for each point is in parenthesis
beside each observation.
It is apparent when considering these two tables that the system does not
readily remove BOD. When comparing the BOD values to the total organic
carbon, it is also evident that much of the organic material is'
not measured as BOD. There is some amount of organic, solvents and hydro-
carbons present that are probably refractory or non-biodegradable under
certain conditions. These materials can come from the printing industry
which utilizes various solvents for scrubbing presses or from an oil which
is added to the dust mops to provide them with the power to pick up dirt
particles. These refractory compounds also have other sources'. A large
portion of this organic fraction is removed after the wastewater oil
emulsion is broken, since the fraction lighter than water will readily
separate in the flotation tank. After flotation, the remaining particulate
matter and oil is readily separated and absorbed by the diatomaceous earth
filter. The remaining TOC is mostly the soluble non-hydrocarbon organic
fraction which is probably biodegradable.
It may be noted in Table 43 that there are considerable amounts of heavy
metals in the wastewater, most notably zinc, lead, and copper. These metals
may affect the BOD analyses at some point during the incubation period.
Laboratory studies demonstrated no lag time during the incubation period,
but they did demonstrate that almost 100% of the BOD was exerted in 5 days,
possibly indicating toxicity at some point before the 5 day period or
before the ultimate 20 day BOD is exerted.
From the TOC/BOD ratio of Table 43, it appears that the presence of refrac-
tory organics cause a high TOC/BOD ratio (average = 2.5) in the raw waste-
water, since theoretically this ratio can be as low as 0.375 for simple
organic compounds. Thus much of the TOC is not oxidized by bacteria.
The presence of toxic heavy metals would also tend to suppress BOD values
by killing bacteria available to oxidize the organic matter. However, the
exact effect these metals might have on sample BOD is not readily discernable
since a fraction of the metals are present as water insoluble forms and as
such would not be toxic during the BOD test. Of course, a certain fraction
is always soluble. It may be noted that the TOC/BOD ratio decreases as
the wastewater proceeds through the treatment system indicating that the
bacteria are more readily able to oxidize the organics present. This
phenomenon could be due to reduction of heavy metal toxicity or refractory
organic removal in the treatment system. Based on these findings, it is
doubtful if BOD is a meaningful parameter for this type of wastewater.
103
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TABLE 42
WASTE TREATMENT EFFICIENCIES FOR VARIOUS PARAMETERS
IN INDUSTRIAL LAUNDRY-WASTE TREATMENT
Parameter
BOD
TOG
Suspended Solids
o Total Solids
*•
Hexane Solubles
Copper
Lead
Mercury
Cadmium
Zinc
Chromium
Iron
Nickel
Average %
Removed by Flotation
24.4 (6)
50.1 (10)
70.0 (9)
25.2 (10)
48.2 (9)
64.8 (8)
59.5 (8)
56.5 (5)
26.7 18)
83.3 (8)
21.1 (8)
83.3 (8)
29.4 (8)
Average %
Removed by System
57.1 (3)
74.0 (6)
88.7 (9)
33.7 (7)
83.4 (7)
68.2 (6)
69.5 (6)
70.8 (5)
35.4 (6)
96.5 (6)
20.6 (8)
92.8 (6)
29.3 (6)
-------
TABLE 43
AVERAGE CONTAMINANT CONCENTRATION
ACHIEVED IN THE INDUSTRIAL LAUNDRY TREATMENT SYSTEM
Diatomaceous
Parameter
BOD, mg/1
Suspended Solids, rag /I
VSS, % of Sus. Solids
TOC, mg/1
Total Solids, mg/1
VTS,-% of Total Solids
Hexane Solubles, mg/1
Chromium, mg/1
Copper, mg/1
Lead, mg/1
Zinc, mg/1
Cadmium, mg/1
Iron, mg/1
Nickel, mg/1
Mercury, Mg/1
TOC /BOD
Raw Waste
830 (6)
2809 (9)
62.7 (7)
2482 (10)
6748 (5)
31.5* (3)
1538 (10)
2.3 (9)
4.0 (8)
12.7 (9)
3.9 (9)
0.24 (9)
39.5 (9)
1.6 (9)
3.3 (5)
2.5 (6)
Flotation
Effluent
611(6)
674 (9)
82.2 (7)
1067 (10)
4693 (10)
25.7 (6)
568 (9)
1.8 (8)
0.7 (8)
2.3 (8)
0.4 (8)
0.23 (8)
1.4 (8)
1.2 (8)
1.0 (6)
1.5 (7)
Earth
Effluent
335 (3)
87 (6)
75.8 (4)
362 (6)
4073 (7)
16.6 (4)
95 (7)
2.0 (6)
0.5 (6)
1.4 (6)
0.1 (6)
0.19 (6)
0.4 (6)
1.2 (6)
0.7 (6)
1.25 (4)
Alkalinity to pH 8. 3 mg/1 as
CaC03, 326* (4)
Alkalinity to r>H 4.5 mg/1 as
CaC03, 1725* (4)
* To pit without CaCl2 addition
+ without I^SO^ neutralization
105
152 (5V
295 (5)
142 (3)"
249 (3)
-------
Table 42 and 43 demonstrate that suspended solids and grease are readily
removed by the treatment system. Approximately 80% of the hexane solubles
and 90% of the suspended matter are removed by the two process elements.
It is also evident from Table 43 that the flotation effluent needs further
treatment to reduce hexane solubles, BOD, suspended solids, and certain
heavy metals to more acceptable levels. Even the diatomaceous earth
filter effluent does not provide the degree of treatment required for all
the parameters as specified in the Chicago ordinance of Table 4. The
average lead and mercury are slightly above the allowable limits.
Dependent upon the wastewater treatment objectives, some form of post
treatment after diatomaceous earth filtration may be required to meet
specified levels of certain contaminants.
A great deal of treatment system variability in performance was noted, as
demonstrated in Tables 44 and 45. The large range of removal percentages
Is significant, and is influenced somewhat by the wide range of raw waste-
water contaminant concentrations. When the influent heavy metal concen-
tration is low or near its limit of solubility, then the percentage removal
of this element approaches zero. This causes the performance of the
wastewater treatment system to appear much more erratic than it actually is
for these elements. It may be noted from Table 42 that the average removal
percentages for these elements other than nickel, chromium, and cadmium
are all near 70%; thus indicating that the removal percentages of the heavy
metals are generally toward the high side of the ranges shown in Table 44.
Because the pH of the wastewater is commonly greater than 10 after the
calcium chloride addition, it is evident that most of the metallic compounds
are present as hydroxide precipitates of some form. Consequently, a liquid
solids separation device is capable of removing heavy metals. It may be
noted that if more conventional coagulants such as alum or ferric chloride
were utilized, the pH required for chemical treatment would probably have
to be between 4 and 6.5. Such being the case, many of the metals removed
at an elevated pH would not be soluble and remain in the wastewater.
Calcium chloride chemical treatment will only work at an elevated pH,
consequently heavy metal removal is a beneficial side effect.
The treatment system has its greatest difficulty in removing nickel,
chromium, and cadmium. The chemical and physical pehnomena that may be
causing this are not well defined, because of the complex chemical nature
of the wastewater and the chemical treatment characteristics.
It can be observed that copper, lead, iron and zinc are consistently
removed in the treatment system. The removal of certain heavy metals
and what fraction of heavy metals are removed is undoubtedly affected by
wastewater pH, organic and inorganic metallic complexing, calcium
chloride dosage, the chemical structure of the metallic compounds, waste-
water temperatures, solution ionic strength, compound solubilities, and
various other items that affect reaction kinetics and chemical equilibria.
It is difficult at best to identify the exact removal mechanism for a
specific heavy metal. However, it may be noted that, even though the
cadmium, nickel, and chromium were not removed to any great or consistent
106
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TABLE 44
o
•vl
Parameter
BOD
'TOC
Suspended Solids
Total Solids
Hexane Solubles
Copper
Lead
Mercury
Cadmium
Zinc
Chromium
Iron
Nickel
RANGES OF WASTE TREATMENT EFFICIENCIES
FOR THE INDUSTRIAL LAUNDRY WASTE TREATMENT SYSTEM
Range of %
Removals by Flotation
0-67
0-93
38 - 98
0 - 54
0-95
0-93
17 - 99
0-91
0-95
36 - 99
0-73
62 - 99
0-70
Range of %
Removal by System
48 - 73
54-95
79 - 99
5-57
34 - 99
0-73
40 - 99
33 - 91
0-95
89 - 99
0 - 88
85 - 99
0-80
-------
TABLE 45
RANGES OF WASTEWATER QUALITY
FOR THE INDUSTRIAL LAUNDRY UASTEWATER TREATMENT SYSTEM
Parameter
BOD, tag/I
Suspended Solids, mg/1
VSS, % Suspended Solids
TOC, mg/1
Total Solids, rag/1
VTS, % Total Solids
Hexane Solubles, mg/1
Chromium, mg/1
Copper, mg/1
Lead, mg/1
Zinc, mg/1
Cadmium, mg/1
Iron, mg/1
Nickel, mg/1
Mercury, pg/1
pH, units
Raw Waste
647 - 1314
649 - 4950
54.5 - 64
950 - 6300
4856 - 8649
21.3 - 43.9
403 - 3756
1.0 - 3.6
0.2 - 9.3
3.0 - 35.8
0.55 - 8.9
0 - 0.6
3.5 - 126
1.0 - 2.5
1.2 - 7.0
10.2 - 11.9
Flotation
Effluent
313 - 1167
108 - 2914
68.2 - 95.1
370 - 2080
3452 - 6670
14.7 - 47.6
146 - 1663
0.9 - 3.2
0.3 - 1.5
0.35 - 3.3
0.02 - 0.6
0.02 - 0.40
0.8 - 2.5
0.3 - 2.0
0.5 - 1.2
10.1 - 11.5
Diatoraaceous
Earth
Effluent
319 - 353
9 - 174
60.6 - 89.9
123 - 470
2876 - 5609
12.5 - 20.0
16 - 266
0.3 - 3.9
0.2 - 0.7
0.1 - 2.2
0.02 - 0.18
0.01 - 0.35
0.2 - 2.4
0.2 - 1.8
0.5 - 1.2
9.8 - 11.45
108
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extent, the effluent concentrations of these materials still meet the
majority of municipal sewer ordinances. It can be concluded that this
treatment technique will remove a significant amount of heavy metals from
industrial laundry wastewater.
System effluent quality data in Table 45 demonstrate that very high
quality water can be produced by the waste treatment system at times.
Effluent suspended solids of 9 mg/1 and hexane solubles of 16 mg/1 are
exceedingly low. Likewise, almost all the heavy metals were removed to
levels less than 0.3 mg/1 at one time or another. From Table 43, the
average wastewater DE effluent quality obtained was quite good, and
suitable for discharge to almost all sewers. A large amount of the organic
matter remaining (TOG) was associated with the dye used at the laundry, as
the effluent was always a pale orange.
Two of the tests performed exhibited no reduction for TOG and grease in the
flotation process, but the diatomaceous earth filter demonstrated 60% to
80% removals for these contaminants during the same runs. Thus, there
were time periods when the flotation tank was not functioning as desired,
and the diatomaceous earth filter acted as the primary solids separator.
Thus the DE filter provides a good backup to the flotation tank, if it is
upset for short time periods.
Because of the erratic performance of the treatment system, it may be
desirable to have a form of post treatment after the DE filter. This could
be a variety of treatment modules - mixed media filters, activated carbon,
demineralizers of various types, chemical oxidation, etc. - dependent on
the contaminant under consideration. For heavy BetaIs, the post treatment
would have to be somewhat more sophisticated, especially if the remaining
metals are dissolved. Here, ion exchange or reverse osmosis might be in
order. Research would be required in this area to establish what would
work and determine what operational problems might be encountered. For
high ihexane soluble or organic contents, extra DE filter capacity or
activated carbon columns would provide the desired effluent quality. In
some instances, no additional treatment will be required, especially for
lower strength wastewaters. It is felt that the present treatment technique
could provide more consistent results if more equalization time, and better
equalization mixing were available, as well as more detention time in the
flotation unit to allow this unit to better handle short surges of high
strength wastewater and provide better solids separation. Twenty minutes
effective detention time would be more desirable than the ten minutes
presently available at an overflow rate of 90 Ipm/sq m (2.2 gpm/sq ft).
During the industrial laundry operation, it was discovered that the
diatomaceous earth filter was not being properly backwashed, because of a
lack of sufficient backwash water. Backwashing the filter at a low flow
rate causes only part of the filter cake to discharge leaving much of the
dirty cake on the filter septums. This soon leads to areas of the filtra-
tion surface becoming completely blinded and bridging of the filter septums
occurs. Consequently, the head loss of the filter builds up more quickly
than it otherwise would, and the effective filtration area is decreased.
109
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This leads to a higher hydraulic loading and a deterioration in effluent
quality. It may be noted that the earlier runs of the DE filter, August
9, 1972 and October 20, 1972, produced effluent much superior to the
January effluents. Likewise, so did the January 30, 1973 run when the
problem was recognized, and the filter cleaned by hand. It is strongly
felt that the need for post treatment is considerably reduced with this
problem rectified, and the DE filtration process properly operated.
The DE backwash during this testing was directed to the heat exchanger pit.
In normal practice, it would be beneficial to direct this flow to another
tank of about 4,000 liters (1000 gal.) capacity to collect the backwash.
This could then be fed to the vacuum filter at a controlled rate for
dewatering with the laundry scum. In summary, it is evident that calcium
chloride chemical treatment at a high pH followed by solids separation is
an effective grease and heavy metal separating technique.
From Table C-4 of Appendix C, it is apparent that even after the printer's
towel wash load was controlled and equalization provided, filter blinding
still manifested itself at times, especially when the printer's towels
were near 20% of the wash load. During the January 26, 1973 operation, the
filter blinded completely due to short circuiting in the equalization basin.
No detention time could be maintained in the equalization basin, due to
the low flow rate coining to it. Consequently, the wastewater that flowed
in was almost immediately pumped out. If this day is-ignored, it is
evident that when the printer's towels are kept at 15% of the industrial
wash load at any one time, and with approximately one hour equalization,
vacuum filter cloth blinding is not a problem.
The amount of sludge generated was significant, and the volume produced
varies directly with the moisture content of the sludge. Generally, the
cake solids obtained were between 25% and 30%. No attempts were made to
optimize the vacuum filter performance, as it nicely kept up with the
scum generated at its lowest cycle time, 5.5 minutes. The submergence
varied with the on-off cycling of the skimmer, but this was not a problem,
as a cake thick enough to discharge was produced. Generally, the vacuum
filter produced 20 to 40 liters of sludge/1000 liters of raw wastewater
treated. The final waste to be disposed of is then about 3% of the
design flow rate.
During the operation of the system, a check valve on the acid neutraliza-
tion system failed such that only limited neutralization data could be
obtained. This part could not be replaced prior to the completion of
the project. The information obtained indicated that 200 to 400 mg
H2S04/1 of wastewater would keep the effluent pH below 10.0. The
alkalinity data obtained from those samples without acid neutralization
indicated that 100 to 250 mg I^SO^/l would be sufficient to neutralize
the flotation effluent pH to 8.3. Thus, it appears that 200 tng/1 l^SO^ is
generally sufficient to neutralize this wastewater to a level suitable
for sewer discharge.
110
-------
During this test work, body feeding the DE filter did not seem to provide
a great increase in the length of filtration runs. Because the solids are
flocculant, they are of a blinding character such that when they are
filtered by the DE, they plug that portion of the filtration surface.
Consequently, DE body feed should be beneficial in that this provides a
new relatively clean, filtering surface. However, the variation in
suspended solids from the flotation unit masked any effect the body feed
rate may have had. When the flotation unit was upset, the pressure
differential built up quickly, and body feed would not have significantly
altered this rate, e.g. October 20, 1972. The character of the other runs
are masked by the problems discussed previously. When the flotation unit
worked well, little pressure buildup was measured indicating that if
the flotation unit performs consistently, a full shift run may be obtained
at hydraulic loadings of 12 to 20 Ipm/sq m (0.3 to n.5 gpm/sq ft) and a
flotation effluent containing 100 mg/1 to 250 rag/1 suspended solids. Thus
DE filtration can be an attractive process for industrial laundry waste-
water treatment in that it is highly efficient at separating solids, utilizes
little floor area, and absorbs oils and greases.
Optimum Treatment System Operating Conditions
Based on the above data and many months experience with the treatment
system, the optimum operating conditions of the wastewater treatment
system were defined and are presented in Table 46. Originally the
system was designed for an overflow rate of 114 1pm/sq-rn, (2.8 gpm/sci ft)
a design flow of 757 1pm,(200 gpm) and 378 1pm (100 gpm) pressurized
flow or 50% recycle, where percent recycle is defined as pressurized flow
over raw flow. However, system operation demonstrated that the optimum
overflow rate of the system is 90 Ipm/sq m (2.2 gpn/sq ft) and that
100% recycle rather than 50% is desirable due to the large concentration
of flocculated solids present. This means the flotation tank has an
optimum flowrate of 446 1pm (118 gpm). The optimum detention time
associated with this flow should be at least 15 minutes. Table 46
reports only 10 minutes for this system due to the limited size of the
flotation unit.
A calcium chloride dosage of at least 2,000 mg/1 as determined by field
observation is required to insure adequate chemical treatment at all times.
The polyelectrolyte is required to strengthen the floe though its dosage
is not critical provided it is above 1.0 mg/1. Likewise, the time between
chemical additions is not critical provided it is greater than about 30
minutes. Generally the vacuum filter can be operated at a cycle time of
5 minutes and filter all the sludge generated. Pickup time and vacuum
level are not critical. The diatomaceous earth filter operated satisfac-
torily when the flotation unit operates well. A flotation unit operated
at the above conditions would provide the consistency required for the DE
filter. Therefore, a body feed ratio of 1 to 2 parts DE per part of
suspended material should prove adequate to achieve an 8 hour DE filter
run, if a 5.3 kg/sq cm (75 psi) differential pressure buildup is allowed
at low hydraulic loadings. This may not always be the case if a flotation
upset occurs. Another problem is significant variation in flow may cause
111
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TABLE 46
GENERAL OPTIMUM OPERATING CONDITIONS
FOR THE INDUSTRIAL LAUNDRY WASTE TREATMENT SYSTE1
Flotation Overflow Rate Based on Raw Flow
Flotation Recycle
Flotation Detention Tine
% Print Towels in Washload
Equalization Tine
CaCl2 Dosage
Polyelectrolyte Dosage
Detention Time Between Two
Chemical Additions
Vacuum Filter Cycle Time
Vacuum Filter Pickup Time
Vacuum Filter Vacuum Level
DE Filter Hydraulic Loading
DE Precoat
DE Body Feed
446 Ipra/sq ft
100%
10 minutes
1 hour
2,000 mg/1
2 mg/1
1 hour
5-5.5 minutes
1. 0-1. 5 minutes
>25 cm Hg.
163 1pm/ sq m
0.74 kg/sq m
1-2 parts DE to 1 part
suspended solids
112
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a loss of filter cake yielding poor effluent quality. Based on the
operation of the treatment system, it is also desirable to keep printer's
towels at less than 15% of the industrial wash load to prevent all
vacuum filter blinding. Table 46 suinaarizes all of these observations.
Table 47 presents the general operating results of the treatment system
exclusive of effluent quality. The solids rise rates were determined
from bench flotation tests in the field performed side by side with the
large flotation tank. Approximately 80 to 120 liters of scum are gener-
ated in the flotation unit for each 1,000 liters of chemically treated
vastewater. Thus scum volume is reduced threefold to fourfold in volume
by the vacuum filter, based on an assumed sludge density of 1.13 gm/cc
(9.5 Ibs/gal.). All sludge volumes were calculated using 1.13 gm/cc (9.5
Ibs/gal.) as the density. The final sludge contains 20% to 30% dry solids
and a large amount of grease and oil. After the sludge is pumped to a
storage bin, it has been liquified to the point where it must be hauled away
as a liquid rather than a solid. The sludge production and handling
system performed as determined in the preliminary laboratory bench tests
after resolving the blinding problem.
The operating costs for the system, as obtained from the field installation
are presented in Table 48. The coagulation chemical cost is based upon
the addition of 2,000 mg/1 calcium chloride and 2 mg/1 anionic polyelectrolyte,
Neutralization costs are based on neutralizing 200 mg/1 excess alkalinity as
calcium carbonate with sulfuric acid. Power costs are calculated from 63
total system horsepower and a unit power cost of 2c/kw hr. Material and
maintenance costs are calculated on the basis of one man being needed half
time to operate the unit at a labor rate of $5.00 per hour. Diatomaceous
earth costs are based on utilizing 200 mg/1 (1.6 lbs/1000 gal.) of
diatomaceous earth as body feed. Sludge disposal costs are $0.012 per
liter ($0.045 per gallon) of sludge.
Capital costs are based on a 20 year life for the system recovered at a
6% interest rate, with an initial investment of $74,298 installed,
in 1971 dollars. The unit amortization operating cost is of course
influenced by the number of shifts the laundry operates; the more shifts
the laundry operates, the lower the unit cost. It has been assumed that
this treatment unit operates for 8 hours at 446 1pm (118 gpm). If the unit is
operated beyond the 8 hour period at a one shift laundry, extra operating
labor cost will be required. This tends to offset any gain in treating
more water (stored in the equalization tank) to bring the amortized
operating cost down. The fixed amortized cost is $24.39/day. For a
one shift operation, the amortization cost is 11.6c/cu m (44C/1000 gal.);
for a two shift operation, the amortized cost is 5.8c cu m (22c/1000
gal.); and for three shifts, 4c/cu m (15C/1000 gal.). It is evident that
amortized capital costs will vary from laundry to laundry dependent on
interest rates, operating labor rates, hours worked, length of time
desired to recover investment, initial investment, size of equipment, etc.
As an example, a 12 year life at 6% would provide amortized costs of
16.6c/cu m (630/1000 gallons) for a one shift operation, 8.4c/cu m
(31C/1000 gal.) for two shifts, and 5.5c/cu m (21C/1000 gal.) for
113
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TABLE 47
INDUSTRIAL LAUNDRY WASTEWATER TREATMENT SYSTEM
OPERATING RESULTS
Flotation Scum Volume
Sludge Volume
Sludge Moisture
Filter Yield
Filter Blinding
Solids Rise Rate
80-120 1/1000 1 raw flow
20-40 1/1000 1 raw flow
70 to 80%
19.6 to 39.4 kg dry solids/sq m/hr
0 to 10%
0.12 - 0.3 mpm
114
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TABLE 48
INDUSTRIAL LAUNDRY WASTE TREATMENT COSTS IN C/CUBIC METER
Item Cost
Coagulation Chemicals 22.5 (16.2)b
Neutralization 1.8
Sludge Disposal 27.2
Power 2.6
Material & Maintenance 6 .6
Amortization - 20 years @ 6% 11.6
Diatomaceous Earth 4.2
TOTAL Cost for Sewer Disposal 76,5 (70.2)
Present Washroom Costs3 7.9 - 18.5
a From laundry wastewater survey
If chemicals bought in bulk
115
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three shifts. The reader may calculate his amortized rate using
any table of capital recovery factors for any design life or interest
rate desirable. Ten percent may be added to the capital cost of the
unit to cover wastewater system engineering. A detailed breakdown of
the demonstration system capital costs is given in Appendix E.
The sludge volume was assumed to be 23 1/1000 1 (23 gal./lOOO gal.)
of wastewater, the average of all runs in Table C-4 except for October
20, 1973, which had abnormally high cake solids. The total operating
cost is almost $0.80/ cu m ($3.00/1000 gal.) of wastewater. This can
be reduced by $0.063/cu m ($0.24/1000 gal.) if the calcium chloride is
handled in bulk as a liquid rather than as individual bags of pellets
as was done during this project. The costs presented can be expected
to vary from day to day due to different wash loads and different
wastewater alkalinities.
The wastewater treatment system operating cost is considerably greater
than present average laundry washroom costs of $0.079 to $0.185/cu m,
1971 dollars, (0.30-$0.70/1000 gal.) of raw water. This cost range
includes sewer taxes, raw water cost, and sewer surcharges for approxi-
mately 70% of a group of laundries surveyed for water consumption and
cost information (See Appendix A). Figure 19 is a frequency distri-
bution for the water costs of those laundries surveyed. It is evident
from this figure and.the treatment system operating cost that water
pollution control is not a money making proposition for laundries in
general. Because of the wastewater characteristics, three t6 six times
more has to be spent on wastewater treatment than is presently spent
on all water related costs.
The operating cost figure given here should not be taken as absolute,
however, as this is.the cost only for the Roscoe Laundry in Chicago,
and applies to industrial (shop towel, printer's towels, and dust mops)
laundry wastewater. The treatment costs presented would be expected
to decrease for weaker laundry wastewater, since not as much sludge
would be generated, and smaller dosages of treatment chemicals possibly
could be utilized. This would lower costs significantly as the coagula-
tion chemicals and sludge disposal costs amount to two-thirds of the
total treatment cost. Likewise, sludge disposal costs vary from place
to place dependent on how the sludge is handled and on sludge moisture
content.
INDUSTRIAL LAUNDRY WASTEWATER REUSE TESTING
On January 30, a water reuse test was performed using diatomaceous earth
effluent to wash shop towels. This was accomplished by filling one
364 kg (800 Ibs) washing machine with effluent to the desired level on a
batch basis for each washing operation. The water was then heated to the
desired temperature with steam prior to commencing the tumbling action
for each wash operation. Samples of each washing machine dump were
then taken to be compared to samples taken from each machine dump of a
116
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25
fl>
u
c
0)
v<
3
O
g
20
15
o
c
-------
control load of shop towels washed the usual way with softened city
water. The same amount of supplies were added to each load. A water
absorption test was then performed on each set of cleaned shop towels
to compare the degree of cleanliness of both loads of shop towels.
Analyses for grease and TOC were performed on samples obtained from the
carryover and ninth rinse cycles of each load. Table 49 presents these
results. It may be noted that all analyses in Table 49 indicate higher
grease and TOC concentrations for the load of shop towels washed with
treated effluent. This could be a result of one load of wipers being
dirtier than the other load or to the use of effluent for washing. The
water used for washing had a grease content of 82 mg/1. No TOC analyses
was available for this water, but it probably measured several hundred
ppm.
A test was performed on cleaned wipers from each load washed, whereby the
time for several wipers to sink to the bottom of a pail is measured.
This is a measure of the water absorptive powers of the wipers. The
wipers washed with treatment system effluent took a much longer time to
sink than those washed with city water, indicating that the wipers
washed with effluent were contaminated with water repelling grease. It
was felt by some observers of this test that the reason for this was the
heating system utilized for the reused water. In the standard way of
washing wipers, the water used to clean them is hot before it enters the
machine, whereas the treatment system effluent was placed in the washer
cold and heated with steam. Putting cold water into the washing machine
after the grease has been emulsified by the supplies and hot water can
cause the grease to congeal and reset itself in the wipers. It is
therefore not known if the difference in the washed products was due to
the water used or the method of heating the water. The results are
inconclusive. It may be emphasized here that the wastewater treatment
system effluent contains red dye, and as such could not be used to
launder anything of a light color.
INDUSTRIAL LAUNDRY WASTEWATER TREATMENT SYSTEM APPLICABILITY
Prom the foregoing discussion of the wastewater treatment system
operation, it is evident that for industrial laundry wastewater of the
strength encountered here, the system modifications previously discussed
are needed to upgrade the consistency of the treatment process. A
larger more completely mixed equalization basin would be desirable in
this respect. This would provide more dilution for strong wastes and
would provide a surge tank for periods of high flow (many washing
machines dumping within a short time interval). This, coupled with
consistent backwashing of the DE filter, assists in upgrading the
effluent quality to the required standards.
However, the treatment method employed obviously is a good step toward
handling metallic and greasy wastewaters emanating from industrial
laundries. It may be noted that other laundries using radically
118
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TABLE 49
REUSE WASTEWATER ANALYSES
FOR TWO LOADS OF SHOP TOWELS ON JANUARY 30, 1973
Sample
Reused Water
City Water
Reused Water
City Water
Wash
Operation
carryover
carryover
ninth rinse
ninth rinse
Grease
TOG
58,712
49,018
604
383
62,700
59,300
810
430
119
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different laundry supplies, e.g. synthetic detergents, may not find
this system exactly suitable for their needs. Previously developed
laundry treatment processes have extensively utilized alum chemical
treatment in combination with various other chemicals (1)(12).
Consequently, those laundries utilizing wash formulas other than the
caustic, silicate, base oil formula used by Roscoe Co., may find that
calcium chloride treatment of their vastewater is ineffective. If
alum chemical treatment were utilized at an industrial laundry, it is
certain that the scum generated by the flotation process could not be
dewatered by conventional vacuum filtration, due to its blinding
qualities. It is similar in nature to the print wiper scum. The
alternatives would be to haul the scum or dewater it on a DE precoat
vacuum filter, both of which would greatly increase already exceedingly
high operating costs. Consequently, it is advantageous to stay with
calcium chloride chemical treatment if at all possible so that a
dewaterable sludge can be obtained (15)(16).
It is certain that preliminary laboratory testing will have to be
performed for all industrial laundries contemplating wastewater treat-
ment to identify those chemicals that will effectively treat the
wastewater. The samples obtained should be 1 to 2 hour composites to
represent the effluent from a moderately sized equalization tank.
Likewise, wastewater analyses are required to identify the problem
constituents. For industrial laundries, alkalinity and hexane solubles
will always be a problem. Therefore, any treatment system installed
must effectively deal with these two parameters.
From the data presented, it is obvious that no biological systems will
be able to treat industrial laundry wastewater. The toxicity of organic
solvents, high temperatures, high pH, and heavy metals is well documented
in the literature (13). A chemcial coagulation, solids separation system
such as the one demonstrated at the Roscoe laundry is required.
At the present time, the treatment concept outlined here is applicable
to those industrial laundries utilizing a wash formula similar to the
one herein described. Other wash formulas would require further
laboratory work to identify the effect of these different supplies on
wastewater treatment. The effect of different types of clientele on
wastewater treatment should also be investigated. The customers of
the laundry will of course have a marked effect on the character of the
wastewater. It is doubtful considering these points and the wastewater
variability encountered, space requirements, variation in flow rates,
and the particular problems under consideration for each laundry if
this system will ever be a standard item. Each one will have to be
custom designed to fit that particular laundry's needs, especially in
view of the complexity of the wastewater itself. Based on these
considerations and the results of initial laboratory testing, it will
be desirable in some cases to perform pilot plant studies to further
120
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prove the merit of the treatment concept chosen. Erratic laboratory
results would indicate the need for pilot plant (40 1pm - 10 gpni) work.
The final factor determining the treatment system concept a laundry
owner might employ is of course the cost of the treatment. For indus-
trial laundries, located in areas with presently existing sewer codes
regulating discharges, the decision on wastewater treatment will relate
to the cost of treatment versus predicted profits. In almost all
instances, dependent upon municipal enforcement attitudes, treatment
will be required. The costs previously presented cannot of course be
taken as absolute due to widely varying circumstances. However, a
laundry owner of a medium size-36,000 to 46,000 kgs (80-100,000 Ibs )
laundered per week -industrial cleaning company should be prepared to invest
at least $40,000 initially and carry a $100 per shift operating cost at
the minimum. The Roscoe plant represents a $75,000 investment (1971)
dollars) and $250 per day operating costs excluding amortization, due to
its exceedingly strong wastewater. The treatment, cost at Roscoe is
about 2.2 cents per kilogram (Ic/lb) of wipers laundered.
It may be said with impunity that industrial laundries washing shop
towels and printer's towels face a significant problem in wastewater
treatment. However, this can be resolved through an expensive capital
outlay. For those laundries whose wastewater is not as strong as the
subject plant, either because of the type of customer or the washing of
a significant amount of other items, the alternatives are not as drastic.
In order to more universally apply the data obtained to other laundries,
more information is needed on the variability of laundry wastewater
characteristics from plant to plant wherein the same items are laundered.
Likewise, information on the effect of different laundry supplies on the
applicability of the treatment system is required. Information on
laundry profit margins would provide a valuable tool for wastewater
treatment break even analyses for given laundry mixes and sizes,
especially if the variation in wastewater quality from plant to plant
were defined from a much more extensive survey than was conducted for
this project. This would provide valuable information on the exact
magnitude of the laundry wastewater treatment problem, both from a
treatability standpoint and governmental attitudes.
121
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SECTION VI
UNIFORM LAUNDRY WASTEWATER TREATMENT
UNIFOFM LAUNDRY WASTEWATER QUALITY
The uniform laundry survey was performed at another Roscoe Co. plant also
located in Chicago. This laundry was visited on March 23 and 24, 1972,
and composite and grab samples of wastewater going to the sewer, and grab
samples of individual washing machine dumps obtained. The sampling pro-
gram was designed to characterize the wastewater discharge from this type
of laundry and to provide samples for bench scale testing to determine if
the wastewater treatment techniques recommended for the shop and printer's
towels would also apply to this wastewater.
This laundry has a wastewater flow of about 284 cu m per day (75,000 gpd)
with a weekly wash load of 36,000 to 41,000 kgs (80-90,000 Ibs). The
plant washes synthetic shirts and pants of various colors, entrance mats,
cottons, uniforms, and some print wipers. The basic supplies include
caustic, sodium metasillcate, and a nonionic detergent (base oil).
Trichloroisocyanuric acid is used as a bleach, sodium silicofluoride as
a sour, and a quaternary ammonium compound as a mildicide. Starch is
also utilized. All samples from the washing machine dumps were analyzed
for total solids, total organic carbon, and pH; with selected samples
analyzed for grease and suspended solids. The effluent composites were
analyzed for these and other compounds and subjected to bench scale
flotation tests.
The results of a series of analyses for loads of synthetic pants, syn-
thetic shirts and uniforms, (coveralls and pants) are presented in Tables
50, 51 and 52, respectively. From these tables, it can be noted that TOC,
total solids and pH decrease with each succeeding rinse and total solids
and TOC increase with an addition in supplies, notably the break and
starch operations. By comparing these tables with Tables 7, 8 and 9
which present similar data for wipers and dust mops, it is evident that
uniform laundry wastewater. is not as potent as that emanating from wipers
and dust mops. In fact, the TOC and total solids appear to be 5 to 10
times less for uniforms. It may be noted that the suspended solids and
grease contents of the suds operations for uniforms were of the same level
as the composite sewer effluent samples obtained from the industrial
laundry, indicating that the average industrial laundry wastewater
pollutional load is equivalent to the worst pollutional load generated
by uniforms. Considering the nature of each article's use, it is evident that
122
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TABLE 50
VARIATION OF UASTEWATER QUALITY WITH WASHING
OPERATION FOR SYNTHETIC PANTS
Operation
Break
Carry Over
Break
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Sour
Starch
2,570
Suspended
Solids-mg/1
2,780
321
110
Total Solids
^/I
6,396
3,520
1,604
958
649
379 .
264
214
79
78
575
21,783
13,429
7,220
3,392
1,781
1,763
1,342
1,145
534
1,011
1,833
12.8
12.7
12.55
12.3
12.05
11.75
11.5
11.25
10.2
5.15
6.7
TABLE 51
VARIATION OF WASTEWATER QUALITY WITH WASHING
OPERATION FOR SYNTHETIC SHIRTS
Operation
Suds
Flush
Suds
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Sour
Starch
Suspended
Solids-mg/1
3,120
86
Total Solids
ng/1
21,916
6,990
12,755
5,016
2,423
1,212
794
570
460
612
7,515
123
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TABLE 52
VARIATION OF WASTEUATER QUALITY
WITH WASHING OPERATION FOR UNIFORMS
Grease
Operation ing /I
Suds 1,700
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Sour 86
Starch
Suspended TOC
Solids-rag /I ng/1
860 5,034
5,544
1,856
586
259
117
83
57
176 50
1,938
Total Solids
niR/1
15,931
12,448
4,383
1,888
765
429
498
360
1,684
4,331
PH
Units
12.5
12.45
12.1
11.6
10.85
10.15
9.7
9.5
4.7
4. 85
124
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the uniforms do not undergo the severe treatment that shop towels do,
even if both are used in the same industry. The shop towels are used
specifically for wiping things up, while the uniforms are used only for
protecting the workers, and generally are not used for direct cleaning up.
The variation in wastewater quality between wash operations is very large,
and again demonstrates the tremendous potential for variation in laundry
wastewater quality. Table C-2 of Appendix C presents the results of
analyses performed in this same survey.
Table 53 presents the water quality of final rinses of various washed
items* A fairly consistent quality is indicated for the uniform items
in that total solids fall between 360-534 mg/1, the pH between 9.5-10.2,
and the TOG between 57-79 mg/1. By comparison, stronger final rinses
can be noted for entrance mats and print wipers. In fact,.the final rinse
quality is similar to that obtained for linens, although the breaks con-
tain a larger amount of contamination than the linens. (See Section VII
of this report.) Comparison of Table 53 with Table 10 also aptly demon-
strates the weakness of uniform wastewater compared to that of industrial
Items. Final rinse TOG, suspended solids, and total solids are all sever-
al times lower for uniforms, even when comparing the sixth or seventh
rinse of uniforms to the tenth or eleventh rinse of wipers.
Table 54 summarizes the analyses performed for the various articles sampled
in terras of kilograms of TOG and total solids per 100 kgs of articles laun-
dered. The uniform plant wastes generated about 2.3-2.5 kgs TOG/100 kgs
laundered and 7-9 kps total solids/100 kgs laundered. Comparing this
table to Table 11 demonstrates that uniforms produce only 5% to 10% of
the wastewater TOC generated by wipers and 20% of the TOC generated by
dust mops. The uniforms produced only 10% to 20% of the total solids
generated by wipers and 15% to 25% of the total solids generated by dust
mops. A series of suspended solids analyses for coveralls indicated about
1.1 kgs of suspended material generated per 100 kgs. laundered, as compared
to 5.8 kgs for a similar set of analyses for print wipers.
Figure 20 demonstrates the wastewater quality variability with time at the
sewer discharge of this laundry. Time zero indicates the time at which
the sampling commenced. The drastic fluctuations observed at the indust-
rial laundry were not as evident for this discharge, due to the fact that
it is sonewhat weaker (see Figure 2, 3, and 4). Suspended solids did not
vary significantly, and were always less than 1,000 mg/1. The variability
of this discharge would not have as adverse an effect on wastewater treat-
Bent as the industrial laundry wastewater variability. However, there is
enough fluctuation to make equalization desirable. The fluctuation may
also be more pronounced if more samples were taken or if the tests were
repeated on a different day.
BENCH SCALE FLOTATION TESTING
Analyses of two full shift composite samples obtained at the laundry are
presented in Table 55. These samples demonstrate a relatively potent
laundry wastewater; more potent than indicated by the uniform analysis of
Table 54. The samples had the same physical appearance as the industrial
125
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TABLE 53
WASTEWATER QUALITY OF FINAL RINSES
FOR VARIOUS LAUNDERED ITE-1S
AT THE ROSCOE UNIFORM LAUNDRY
Article
Laundered
Uniforms
Shirts
Pants
Coveralls
Uniforms
Entrance Mats
Shirts
Print Rags*
PH
Units
9.5
10.05
10.2
9.7
9.5
10.6
10.1
9.3
TOC
57
64
79
67
64
373
66
378
Suspended
Solids-mg/1
176
126
110
128
60
385
86
240
Total Solids
mg/1
360
524
534
469
374
1,093
460
633
* After 13th rinse; rest of items had only 6 to 7 rinses.
126
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TABLE 54
ESTIMATED WASTE LOAD QUANTITIES
FROM UNIFORM LAUNDERING OPERATIONS
Article
Laundered
Shirts
Print Rags
Uniforms
Shirts
Pants
Coveralls
Uniforms
Entrance Mats
kes TOG/
less of Article
2.23
11.54
2.47
2.53
2.34
1.73
0.87
9.94
100
Laundered
p,s Total Solids/]00
k%s Article Laundered
11.36
2,0.91
6.89
9.23
8.90
6.91
6.80
22.39
127
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00
Suspended Solids
' I
3 4
Tine From First Saraole - Hours
VARIA3ILITY OF WASTEI-7ATEK QUALITY WITH TIME AT THE
20
c
DISCHARGE FOR A UNIFORM LAUNDRY ON 5/24/72
-------
TABLE 55
COMPOSITE WASTEWATER ANALYSES OF
UNIFORM LAUNDRY WASTEWATER ON
MARCH 23 and 24, 1972
Analysis
Total Solids, mg/1
Total Volatile Solids, mg/1
Suspended Solids, mg/1
Volatile Suspended Solids, mg/1
pll, units
Alkalinity, mg/1 as CaC03
Grease, mg/1
TOC, mg/1
COD, mg/1
Soluble BOD, mg/1
Copper, mg/1
Iron, mg/1
Chromium, mg/1
Lead, mg/1
Mercury, yg/1
Cadmium, mg/1
Zinc, rag/1
Cyanide, mg/1
Phenol, mg/1
3/23 Composite
3,845
2,153
685
565
11.9
1,272
734
1,832
608
147
1.8
16.3
2.4
9.8
1
<0.01
3.4
0.7
0.5
3/24 Composite
3,053
1,469
425
' 365
11.8
1,230
340
1,349
534
203
2.3
14.5
1.4
6.8
3
<0.01
3.8
0.36
1.2
129
-------
laundry wastewater composites. If It is assumed that 6,800 kgs of uniforms
are laundered and produce 2.5 kgs of TOC per 100 kgs cleaned and 8.0 kgs
of total solids per 100 kgs cleaned in 302 cu m (80,000 gal.) of wastewater;
a wastewater TOC concentration of 562 mg/1 and a wastewater total solids
concentration of 1,800 rag/1 are predicted. This is considerably lower
than the 1,400 to 1,800 rag/1 TOC and 3,000 to 3,800 mg/1 total solids
concentrations actually measured. Evidently, the print rags and
entrance mats are contributing a large portion of the contamination
to the wastewater, since more total solids and TOC are associated with
these items. It is also likely that the majority of the heavy metals
are associated with the print wipers. Table 56 aptly demonstrates that
this is the case. The suds operation of two print wiper wash cycles were
analyzed for various constituents, and it was found that there was enough
lead in suds sample 2 to contribute 252 to 40% of all the lead found in
the composites, i.e.» one machine dump or 1/2 of 1% of the total plant
flow can contribute 40% of the lead to the effluent. It may also be noted
that very high levels of chromium, zinc, and copper are also present. In
a case like this, a significant reduction in effluent heavy metals could
be affected by no longer laundering these types of articles. For a plant
in which this type of article makes up only a small portion of its business,
an economical solution to the waste problem would be elimination of the
laundering of this article. This may shift the disposal problem elsewhere,
or it may force the industry involved to resolve the problem by changing
their practices. In either case, the handling of the heavy metals problem
would be more practical elsewhere.
Table 56 gives evidence that the printer's towels dominated this wastewater
and contributed excessive quantities of grease, TOC, and heavy metals. Thus
the effluent composites did not reflect a pure uniform laundry wastewater.
In spite of this, the vastewater total solids, TOC, BOD, grease, and sus-
pended solid contents were still considerably lower than were those com-
posites reported in Table 3 for industrial laundry wastewater. Therefore,
this wastewater would not be expected to generate as much sludge as the
industrial laundry wastewater.
Bench scale flotation tests were performed on both of the composite
samples obtained, the results of which are presented in Table 57. It
can be seen that reductions in suspended matter, TOC, grease, and heavy
metals were affected. Calcium chloride treatment provided effective
flocculation, and solids rise rates comparable to industrial laundry
wastewater bench tests results were obtained. Flotation solids separ-
ation for uniform wastewater was feasible. Good reductions of almost all
contaminant concentrations were obtained. TOC and suspended solids
removals of 80% were similar to those obtained for the industrial laun-
dry wastewater. All heavy metals measured were removed to a large degree,
as is the case for industrial laundry wastewater treatment. It was con-
cluded that the treatment system presently employed at the Roscoe
industrial towel plant would be applicable to this plant's wastewater,
as well as uniform wastewater by itself. It is generally acknowledged
that the same type of wastewater would be obtained without the printer's
towel contaminant contribution, only of a lower strength. Consequently,
130
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TABLE 56
ANALYSIS OF PRINT WIPER SUDS AT THE ROSCOE UNIFORM
LAUNDRY ON MARCH 24, 1972
Analysis Sample 1 Sample 2
Mercury - yg/1 14 14
Zinc - mg/1 7.2 8.0
Copper - mg/1 31 6.8
Chromium - mg/1 13.6 124
Lead - mg/1 79 ' 513
Total Solids - mg/1 20,504 32,107
TOC - mg/1 51,000 32,400
pH - units 13.0 12.7
Suspended Solids - mg/1 5,500 10,900
Grease -mg/1 11,829 22,305
131
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TABLE 57
RESULTS OF T5E15CI1 SCALE
FLOTATION TESTS OF UNIFORM LAUITDRY COMPOSITE SAMPLES
OF MARCH 23 and 24, 1972
Test Mo.
Waste Used
Ch em i ca 1 Tr e a tni en t:
CaCl2»2Il 0 (mg/1)
Na2CO~3 - rag/I
Polyelectrolyte
Mix Time, min.
Flocculation Tirae, min
Recycle ]late, %
Detention Time, rain
Rise Rate, mpm
Scun Volume, 1/1000 1
Sludge Volume, 1/1000 1
Effluent Quality:
pll, units
Suspended Solids, iag/1
Grease, n.g/1
Total Solids, mg/]
TOC, r.ij>/I
Copper, ng/1
Iron, r.ig/1
Lead, n?/l
Zinc, mg/1
Chrbraiura, mg/1
Percent Reduction in:
Suspended Solids
Grease
Chromium
Copper ;
Lend
Zinc
TOC
1
3/23/72
2,000
2 Bg/1
Hercofloe 905N
0.25
2
33
8
0.18
97
trace
11.5
155
118
2,631
332
0.6
0.7
1.1
0.24
1.7
77
84
29
67
89
93
82
3/24/72
2,000
1,000
2 mg/1
Nalco 675
0.25
2
33
8
0.28
105
trace
11.5
27
72
3,015
305
0.4
0.3
0.4
0.05
0.8
94
79
43
81
94
99
77
3/24/72
2,000
2 ng/1
Nalco 675
0.25
2
33
8
0.34
90
trace
11.5
154
91
2,891
338
0.5
0.4
0.8
0.17
0.8
64
72
43
79
88
96
75
132
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the treatment concept developed for industrial laundry wastewater should
apply to uniform laundry wastewater.
UNIFORM LAUNDRY WASTEV7ATER TREATMENT SYSTEM EFFLUENT QUALITY
After completing the operation of the wastewater treatment system on
industrial laundry wastes, the unit was operated on pure uniform laundry
wastewater. This was accomplished by hauling uniforms from the Roscoe
uniform laundry to the wastewater treatment site and laundering the
uniforms in the linen washing machines shown in Figure 1. This task was
performed in a manner that would cause as little interference as possible
in the laundry's normal work schedule and operation. The water discharged
from the uniforms went directly to the equalization pit from where it was
Dumped back to the treatment system. Six different uniform wastewater
treatment tests were performed in this manner utilizing only the washwater
from synthetic pants, synthetic shirts and coveralls.
Table C-7 of Appendix C presents the operating conditions of the waste-
water treatment system for this test work. Table C-8 lists the vacuum
filtration data and Table C-9 the effluent quality analyses. Each test
was performed for as long a time as possible, until the equalization pit'
was empty of water. The February 7 run v?as contaminated with print wiper
wastewater when the dam separating the industrial wastewater from the
uniform wastewater failed. Only limited analyses were performed for this
test. Two sets of operating conditions are presented for February 13,
but sample analyses were performed for only the second test. February 13
was also the wastewater reuse test. Heavy metal analyses were made for
the February 6 and February 13 tests. All samples analyzed were composites
for the length of the test. The raw wastewater and scum were composited
manually, while all other samples were composited automatically.
The unit was operated at a widely varying set of conditions; but no
reasonable trends or correlations were demonstrated between suspended
solids removal rates and calcium chloride dosage, recycle ratio, surface
overflow rate, or mass loading. These independent variables also did not
correlate with grease removal rates or effluent suspended solids. This
is due in part to the limited amount of data, and to the varying waste-
water quality. It may also be noted that the equalization pit was not
•cleaned prior to the start of the uniform testing. Thus some grease and
solids may have been picked up in the pit during the initial tests. Since
all but one raw x^astewater sample was obtained for water going to the pit,
the analyses would not reflect this.
The percentage grease removal increased relatively progressively with test
date, from QZ to 40% for all tests. Scum samples analyzed for grease
indicated that grease or hexane soluble separation was occurring in the
flotation system. Table C-8 of Appendix C shows scum grease contents
varying from 834 nr,/l to 10,134 mg/1. On both days, February 2 and 6, 1973,
demonstrating zero grease removal, the scum samples contained 2,000 mg/1
grease. Evidently, the uniform wastewater was picking up some ^articulate
133
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grease from the equalization pit, which was then separated in the flotation
tank. The one test, February 7, where raw wastewater was obtained coming
from the pit contained 1,888 mg/1 grease. This was the test suffering from
print wiper contamination, but it may also reflect some pickup of grease
from the equalization pit. In any case, the influence this may have had
on the performance of the flotation unit is unknown at this time. Con-
sequently, only the average wastewater quality will be discussed as was
done for the industrial wastewater. The February 7 analyses will not be
included in the discussion due to the printer's towel contamination*
Table 58 presents the average wastewater qualities for the various treat-
ment system points for all the data presented in Table C-9 of Appendix C.
The numbers in parentheses beside each average value indicates the number
of data points that the average represents. Table 59 presents the ranges
of values for those averages representing more than two numbers.
From both Table 58 and Table 59, it is evident that the flotation unit is
removing, little organic matter, as determined by flotation effluent and
raw wastewater samples obtained prior to the equalization pit; either
measured as BOD, TOC, or grease. The samples thus do not reflect any
settling or res us pens ion that may have occurred in the pit, and this may
have influenced the results. However, it would appear from this data
that the majority of the organic matter obtained from the uniforms must
be soluble, and not amenable to reduction by a solids separation device.
€alcium chloride treatment and solids separation did not affect a signif-
icant reduction in grease. The levels of TOC, BOD.and hexane solubles
measured were considerably lower than those measured for either the indust-
rial laundry wastewater or the composite obtained at the Roscoe uniform
plant (see Table 55) • Thus the printer's towels were contributing much
organic matter to the composites obtained at the uniform laundry. It
may be noted that the February 13 test utilizing the DE filter produced
an excellent effluent quality affecting a 46% reduction in BOD and a 58%
reduction in TOC and an effluent grease concentration of 26 mg/1. It is
apparent that the DE scrbed out the grease that could not be removed in
the flotation unit. The reduction of the grease caused a corresponding
drop in BOD and TOC. Evidently, for the type of organic matter and hexane
soluble material present in uniform wastewater, EE filtration is necessary
to reduce the grease concentration to acceptable levels, i.e., 100 mg/1.
This is necessary to insure that this level is met 100% of the time. Other
types of filtration such as sand or mixed media do not readily absorb
emulsified grease.
Due to the above observations concerning grease removal, it is appealing
to consider only utilizing DE filtration for this type of wastewater.
This would provide adequate grease removal, but the presence of 1,000 mg/1
suspended solids would lead to quick plugging of any DE filtration system.
Consequently, a preliminary solids separation device is necessary to remove
the majority of the suspended material prior to the DE filter. The flota-
tion unit did this nicely removing an average of 71% of the suspended
material and providing an effluent with less than 250 mg/1 suspended
solids at all times. This is desirable to prevent using a lot of expen-
sive diatomaceous earth. That the DE filter does not plug up fast is
134
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TABLE 58
AVERAGE WASTEWATER QUALITY
FOR UNIFORM LAUNDRY WASTEWATER TREATMENT
U)
Ul
Parameter
BOD, iug/1
TOO, mg/1
Total Solids, mg/1
Volatile Total Solids, % of
Total Solids
Suspended Solids, nig/1
Volatile Suspended Solids, % of
Suspended Solids
Grease, mg/1
Copper, mg/1
Lead, mg/1
Mercury, VJg/1
Cadmium, mg/1
Zinc., mg-/l
Chromium, mg/1
Nickel, ing/1
Iron, mg/1
Alkalinity to pll 8.3, mg/1
as CaC03
Alkalinity to pH 3.7, mg/1
as CaC03
Average Value
297 (4)
553 (5)
4,215 (5)
30.8 (5)
1,003 (5)
49.0 (5)
234 (5)
4.4 (2)
5.1 (2)
3.6 (2)
0.14 (2)
7.0 (2)
0.88 (2)
1.0 (2)
46.5 (2)
623 (5)
Flotation
Effluent
Average
Value
288 (4)
474 (5)
5,663 (5)
15.6 (5)
169 (5)
70.4 (5)
190 (5)
0.42 (2)
1.3 (2)
0.7 (2)
0.015 (2)
0.54 (2)
0.14 '(2)
1.0 (2)
1.4 (2)
259 (5)
Average
Diatomaceous* Flotation
Earth Percent
Effluent
124
225
4,443
17.0
30
90
26
0.1
0.9
0.6
0.02
0.03
0.11
0.7
0.8
110
Removed
7.0 (4)
13.2 (5)
—
—
70.8 (5)
__
17.1 (5)
72.6 (2)
74.1 (2)
79.6 (2)
89.5 (2)
92.3 (2)
62.3 (2)
5.0 (2)
96.1 (2)
—
Percent*
System
Removed
45.6
58.3
— —
—
96.6
—
92.0
98.7
86.2
86.0
86.7
99.5
93.1
30.0
98.9
—
1,076 (5)
402 (5)
185
Represents only one series of analyses.
-------
TABLE 59
RANGES OF WASTEWATER QUALITY
ENCOUNTERED IN UNIFORM LAUNDRY
WASTEWATER TREATMENT
Range
Range Flotation
Raw Wastewater Range Flotation Effluent
Parameter Values Effluent Values Percent Removed
BOD, mg/1 192 - 473 274-449 0-7.1
TOC, mg/1 400 -. 765 335 - 570 0 - 25.5
Total Solids, mg/1 2,801 - 6,967 3,531 - 6,900
Volatile Total Solids,
% of Total Solids 18.3 -40.6 9.3 - 21.8
Suspended Solids, mg/1 316 - 1,765 67 - 243 23.1 - 95.8
Volatile Suspended
Solids, % of Sus.
Solids 32.8 - 73.7 46.1 - 95.5
Grease, rag/1 122 - 369 107 - 242 0 - 38.9
Alkalinity to pH 8.3,
ng/1 as CaC03 255 - 945 25 - 735
Alkalinity to pH 3.7,
mg/1 as.CaC03 820 - 1,365 195 - 890
X36
-------
evidenced by the 0.5 kg/sq cm/hr (7.0 psi/hr) DE differential pressure
increase during the February 13 test at a hydraulic loading of 13 Ipjn/sq m
(0,33 gpro/sq ft). This may allow 10 hours of operation before the filter
would have to be backwashed and precoated again, i.e., one full shift of
operation. It is therefore desirable to keep the flotation and DE filtra-
tion modules in series as installed at the Roscoe laundry, for uniform
laundry wastewater treatment.
Table 58 demonstrates that uniform wastewater contains heavy metals
considerably above trace levels. The uniform wastewater contains heavy
metals at about the same concentrations as the industrial laundry waste-
water (compare Table 43). The industrial laundry wastewater is higher in
lead and chromium, while the other metals are approximately at the same
levels. Since the raw uniform wastewater samples were obtained prior to the
pit, no heavy metal contamination of the uniform samples can be attributed
to this source. Therefore, the conclusion drawn is that uniforms are a
significant source of heavy metals at this particular laundry. It is
difficult to say what the exact source of the heavy metals might be, due
to the many clients and diversified number of industries that utilize the
laundry's service. It is probable that this problem is prevalent at many
laundries handling uniforms used at service stations or in metal products
manufacturing.
From Table 58 it is evident that the uniform wastewater treatment system
readily separated all heavy metals measured except nickel. Copper, lead,
mercury, cadmium, zinc, chromium and iron were all effectively reduced in
the flotation and DE filtration steps. The removal mechanism is the same
as previously discussed for industrial laundry wastewater treatment; Solids
separation at a high pH was useful in causing a reduction in heavy metals.
UNIFORM LAUNDRY WASTEWATER TREATMENT SYSTEM OPERATIONAL RESULTS
The mechanical operation of the uniform laundry wastewater treatment system
was good for all six days of testing. The flotation system separated large
amounts of gray solids concentrating them to 0.5% to 3% suspended solids,
the entire range of which proved suitable for vacuum filtration. The solids
generated were those present in the laundry discharge and those precipitated
by the calcium chloride. Good reductions in suspended material were
obtained at overflow rates of 94 Ipm/sq m (2.3 gpm/sq ft) and recycle
ratios of 75%. The unit could possibly have performed well at even higher
hydraulic loadings, but this was the maximum output of the equalization pit
return pump. Consequently, this flotation tank is rated at 541 1pm (143 gpm)
for the uniform laundry wastewater treated at this facility. A lower
recycle ratio may also be possible for this wastewater due to its lower
solids content, with the lowest possible ratio being 50%.
Good visual flocculation was achieved at all calcium chloride dosages
utilized during this test work. It was generally observable that 2,000 mg/1
calcium chloride was the optimum dosage providing a very large tough floe.
Two mg/1 of anionic polyelectrolyte helps considerably in enlarging the
floe and strengthening it.
137
-------
At no time during the testing was vacuum filter blinding a problem. The
sludge always readily filtered and was not sensitive to filter operating
conditions. Table C-8 of Appendix C presents all the vacuum filter
operating data obtained during the study. The cake would not dewater
beyond 15% to 20% cake solids, as it would crack at this solids content and
the vacuum level would decrease on the dry cycle. The filter yield obtained
was found to be directly proportional to the average scum suspended solids
concentration, as shown in Figure 21. This is typical of vacuum filter
installations, and according to vacuum filtration theory (14). Vacuum
filtration is an effective means for dewatering sludge obtained from
uniform laundry wastewater. The vacuum filtrate was of as good a quality
as the flotation effluent.
The DE filter test performed, as pointed out previously, was satisfactory In
that it did not quickly plug, and provided effective suspended solids
reduction. A body feed rate of 3.0 mg DE per mg of suspended material led
to a differential pressure buildup of only 0.5 kg/sq cm/hr (7.0 psi/hr).
Consequently a body feed rate of 2.0 mg DE/mg suspended solids is probably
adequate for a flotation effluent containing 200 tng/1 suspended solids at
a filter hydraulic loading of 18 Ipm/sq m (0.45 gpm/sq ft).
The optimum uniform treatment system operating conditions are presented in
Table 60. The conditions of operation are generally the same as recommended
for the industrial laundry wastewater treatment system, (see Table 46) t
except that the flotation process does not require as much effluent recycle,
and can be loaded at a slightly higher hydraulic level. It would also be
desirable to have a 15 minute flotation detention tine for this wastewater,
to allow for increased liquid solids separation. The recommended chemical
treatment and vacuum filter operation are the same as for the industrial
laundry wastewater. The Moyno sludge pump also caused this material to
liquify requiring liquid hauling of the sludge. The DE filter recommendatons
are the same as previously discussed.
Table 61 presents the general operating results of the treatment system.
Approximately the same amount of flotation scum was produced as for the
industrial laundry wastewater. However, the low influent suspended solids
caused the low scum solids and led to fairly large final sludge volumes
of high moisture content. Generally this scum did not filter as well as
the industrial laundry scum as the vacuum filter produced lower yields and
cake solids, due to the lower solids concentrations. This leads to more
water being associated with the sludge and consequently to higher sludge
volumes per unit mass of solids. It may be feasible that a larger flotation
unit providing more detention time would allow the scum to thicken to a
higher concentration and provide enough reduction in sludge volume to offset
the cost of the larger flotation unit. Generally 11 to 15 liters of sludge/
1000 liters of raw flow were produced', based on a sludge density of 1,077
fee (9.0 lb/gal.).
138
-------
c*
CO
a
QJ
1.5
1.5 2.0 2.5
Suspended Solids - /'
3.0
FTCURr 21
VARIATION OF FILTER YIELD T.'ITH UNIFORM FLOTATION SCUM SOLIDS
3.5
-------
TABLE 60
GENERAL OPTIMUM OPERATING CONDITIONS
FOR THE UNIFORM WASTEWATER TREATMENT SYSTEM
Flotation Overflow R.ate
Flotation Recylce
Flotation Detention Time
Equalization Time
CaClo Dosage
Polyelectrolyte Dosage
Detention Time Retween Two Chemical Additions
Vacuum Filter Cycle Time
Vacuum Filter Pickup Time
Vacuum Filter Vacuum Level
DE Filter Hydraulic Loading
DE Precoat
DE Body Feed
96 Ipm/sq m
75%
n- .5 minutes
1 hour
2,000 ng/1
2 mg/1
1 hour
5.5 minutes
1.0 - 1.5 min.
>25 cm Hg
18 Ipm/sq m
0.73 kg/sq m
2 parts DE to 1
part Suspended
Solids
140
-------
TABLE 61
GENERAL OPERATING RESULTS OF THE UNIFORM TREATMENT SYSTEM
Flotation Scum Volumes
Sludge Volume
Sludge Moisture
Filter Yield
Filter Blinding
Vacuum Filtrate Flow
DE Pressure Buildup
80 to 100 1/1000 1
raw flow
10 to A 1/1000 1
raw flow
80 - 90%
10 - 15 kgs/sq m/hr
0%
40 - 80 1pm
0.5 kg/sq cm/hr
141
-------
UNIFORM WASTEWATER TREATMENT SYSTEM OPERATING COSTS
Operating costs for the uniform laundry wastewater treatment operation, as
obtained from the field installation are presented in Table 62. The
chemical coagulant cost is based upon the addition of 2,000 mg/1 calcium
chloride and 2 mg/1 anionic polyelectrolyte. Neutralization costs are
based on neutralizing 200 mg/1 flotation effluent alkalinity as calcium
carbonate with sulfuric acid. Unit chemical costs are $5.17/kg ($2.35/lb)
for the polyelectrolyte $0.088/kg ($0.04/lb) for sulfuric acid, and
$0.102/kg ($0.0465/lb) for calcium chloride. Power costs and material and
maintenance costs are the same as for industrial laundry wastewater
treatment. Diatomaceous earth costs are based on the addition of 0.477
grams (4 Ibs per 1000 gal.) of DE per 1 liter of wastewater. Sludge
disposal costs are $0.012/liter ($0.045/gal.), based on an average
of 13 liters of sludge per 1000 liters of wastewater treated (See Table 48).
Capital costs are based on the same conditions utilized for the industrial
laundry wastewater. The unit costs are lowered because of the greater
capacity of the flotation tank for uniform laundry wastewater. For a two
shift operation, the amortization cost would be 4.7£/cu ra (18C/1000 gal.)
wastewater and 3.2c/cu m (12C/1000 gal.) wastewater for a three shift
operation. The same observations made for the industrial laundry regarding
capital costs hold true for uniform laundries. The total operating cost
was then 66.8c/cu m ($2.53/1000 gal.) treated at this laundry with the
costs reduced to 60.4c/cu m ($2.29/1000 gal.) if chemicals are handled in
bulk rather than by hand.
Thus, it is evident that even the weaker uniform wastewater costs a consid-
erable amount to treat. However, the nature of the wastewater, its grease
content (>100 mg/1) and heavy metal content, make treatment imperative in
urban areas. The operating costs presented here would be expected to vary
from laundry to laundry dependent on sludge handling methods, wastewater
flow rate, chemical treatment methods, wash load mix, etc. Each laundry
will have to determine its own costs dependent on its own situation.
UNIFORM LAUNDRY WASTEWATER REUSE TESTING
The February 13 wastewater DE effluent was used in a water reuse test to wash
a load of synthetic pants. The test was performed in the same manner as the
reuse test for industrial wipers, except no control samples of machine
dumps were obtained. Analyses for the carryover and fifth rinse operations
were performed to determine if the discharged water was significantly poorer
in quality than that obtained from the industrial laundry survey performed
on March 24, 1973, when softened city water was used to launder the same
items. Table 63 presents the results of these analyses as compared to
samples obtained from a load of synthetic pants laundered on March 24, 1972.
As in the industrial laundry wastewater reuse test, all analyses indicate
that the reused water discharge is more contaminated with organic materials
and solids than the city water regularly used for washing. By the fifth
rinse, the washing machine discharge is approaching the quality of the DE
filter effluent of February 13, 1973.
142
-------
TABLE 62
UNIFORM LAUNDRY WASTE TREATMENT COSTS III C/CUBIC METER
Item Cost
Coagulation Chemicals 22.5 (16.1)a
A
Neutralization 1.8
Sludge Disposal 15.3
Power 2.6
Material and Maintenance 6.6
Amortization - 20 years @ 6% 9.5
Diatoraaceous Earth 8.5
TOTAL Cost for Sewer Disposal 66.8 (60.4)a
(a) If chemicals bought in bulk
143
-------
TABLE 63
REUSE KASTEWATER ANALYSES
FOR TWO LOADS OF SYNTHETIC PANTS
Sample
Reused Water
City Water
Reused Water
City Water
Wash Operation
Carryover
Carryover
fifth rinse
fifth rinse
12.6
12.7
11.2
11.25
TOG Total Solids
5,620 21,000
3,520
355
214
13,429
5,069
1,145
144
-------
It is obvious that reusing the wastewater will result in an increase in
dissolved material in the laundry process water. From Table C-9, it is
also apparent that calcium hardness is a problem, as 860 nig/1 calcium
was measured in the DE effluent composite. Based on the fifth rinse
quality, it appears that approximately 4,500 mg/1 of total solids were
added to the wash water, on a once through basis. It was not possible to
determine if the same amount of solids would be added, if the same water
were treated and reused again. It is anticipated that the solids would
keep building up at a decreasing rate until an equilibrium level was
reached (1). It is obvious that the calcium hardness and dissolved solids
content is going to limit the extent of wastewater reuse. This aspect is
discussed in detail in Section VIII for various laundry wastewater types.
Both process feasibility and economics are included in the discussion.
The laundry personnel at the plant examinated the cleaned pants and
compared them to pants laundered with regular city water, and found no
differences in the cleaned garments. The metal buttons on the pants showed
no traces of grease smears, and neither did the metal cylinder on the wash
wheel. Several people in authority examined the garments and agreed
the quality of the pants had not suffered. Thus the limitations on reusing
wastewater treatment system effluent for laundering uniforms lies not with
degrading the uniforms, but in providing a suitable water quality.
UNIFORM LAUNDRY WASTEWATER TREATMENT SYSTEM PROCESS EVALUATION
AND APPLICABILITY
Due to the similarity of the uniform laundry and industrial laundry waste-
water characteristics, the observations made for industrial laundry
wastewater treatment regarding supplies, biological treatment methods,
wastewater variability from laundry to laundry, and general design philosophy
hold true here also. The presence of heavy metals at the levels encountered,
notably lead, zinc, and copper makes wastewater treatment a necessity rather
than an economic alternative. Hexane soluble and alkalinity concentrations
are also problems that must be dealt with. The treatment system utilized
for the Roscoe uniform wastewater demonstrated that all sewer standards
can be met by flotation, diatomaceous earth filtration waste treatment. -
It was evident that the flotation process by itself would not do the
required treatment job.
If heavy metals are the major problem at the uniform laundry, it will be
necessary to perform pilot plant studies at that laundry, because of the
complexity of the problem and the need for determining the consistency
with which the particular metallic components under consideration are
removed. If heavy metals are not a problem at the uniform laundry, the
treatment system can be sized from appropriately obtained composite samples
and bench scale testing. This is true of those laundries where the main
problems are suspended solids and hexane solubles.
When heavy metals are a problem, the laundry owner may consider changing
his supplies to the caustic-silicate formula Roscoe utilizes so that
calcium chloride will provide the treatment required at an alkaline pH.
145
-------
If the metals were to be removed by ion exchange, reverse osmosis, or
other sophisticated techniques, a relatively suspended solids free water
must be supplied for these systems. Thus the diatomaceous earth effluent
would go to a heavy metals separator and add considerably to the treatment
cost. It is much cheaper to remove the metals in a suspended solids
separator. Likewise, any change in the calcium chloride treatment
technique, e.g., to alum, would result in a relatively nondewaterable scum.
Consequently, expensive precoat vacuum filtration would have to be used to
reduce sludge volumes; or a much larger volume of liquid waste, the scum
itself, would have to be hauled away (15). Either technique would result
in a significantly higher cost than the 60.5c/cu m ($2.29/1000 gal.) of
wastewater presented here. Thus a change in the wash formula in a case
like this can prove economical. The full justification for such a move
could only come from laboratory testing and the laundries' own situation.
The economic considerations for uniform laundries are similar to the
industrial laundry situation. A capital outlay of at least $40,000 will
be required for a medium sized uniform laundry with a minimum of $100 per
shift operating costs. Treatment of uniform wastewater is npt a profitable
picture either, though better than for those laundries cleaning shop towels.
In all cases, either reduced profits or price increases are going to be
involved. The unit price for washing uniforms would increase l.lc to 2.2?
per kilogram (0.5 to l.Oc/lb) laundered if one figures that approximately
33.3 liters of wastewater are treated for each kilogram (4 gals./lb) of
uniforms laundered after allowing for evaporative losses. The treatment cost
for the Roscoe plant would be 1.9c/kg ($.0085/lb) for their laundered
uniforms. The alternatives of treatment versus other measures can be
determined on a product unit cost basis.
More information is needed on the variation in quality of uniform laundry
wastewater so that more concrete economic alternatives than the above can
be formulated. Information on the economic considerations of changing the
laundry supply system to be compatible with the treatment unit is also
required. This study has demonstrated that uniform laundry wastewater
can be treated effectively, but information on the variety of uniform
laundry wastewater characteristics is required in order to determine the
degree of applicability of the treatment system. It is likely that the
flotation-filtration system will be applicable in most cases, but the
chemicals, size, and operating costs may vary significantly with
wastewater quality.
146
-------
SECTION VII
LINEN LAUNDRY WASTEWATER TREATMENT
LINEN LAUNDRY WASTEWATER QUALITY
A linen laundry wastewater survey was performed at the same Roscoe
laundry where the treatment system existed. Those three machines at the
Roscoe laundry washing linens were utilized for the survey work. This
was logical since these linen wastes would be the ones treated by the
demonstration unit. The survey was performed on May 19 and 20, 1971.
Grab samples were obtained from each washing machine dump for the entire
washing cycle for continuous towels, kitchen towels, tablecloths, and
napkins to characterize the wastewater emanating from these articles. It
was hoped that a composite sample of linen wastewater could also be
obtained. However, because the linen machines discharge into the same
channel as the industrial washing machines, the wiper and dust'mop waste-
water often backed up into the linen area making it difficult to obtain a
composite sample of only linen wastewater. Therefore, grab samples were
obtained from the linen flow when it appeared that it was not contaminated
by industrial wastewater, and later composited for bench scale treatment
tests.
All samples were analyzed for total solids, total organic carbon,
and pH. Other samples were analyzed for suspended solids and alkalinity.
Bench scale chemical treatment tests were performed on the grab samples
to define the effect of linen wastewater variability on the chemical
treatment process.
The supplies used for the linens include an anionic detergent and a
tallow soap with a titer of 40-42 for removing the soil. The base oil
etnulsifier used for the wipers and uniforms is also added to the linen
wash cycle, though in lesser quantities. These supplies are added to
each of two suds operations or breaks. Bleach is added as sod'ium hypo-
chlorite or isocyanuric acid. The last cycle has ammonium silicofluoride
added for pH adjustment and a chlorohydrocarbon mildicide added. Starch
is added to the sour operation when it is required. The detergent
utilized was of the caustic silicate variety, so that this wastewater
also contains a lot of dissolved silica.
147
-------
The results of a typical series of analyses for a 364 kg (800 Ib) load
of kitchen towels and a 136 kg (300 Ib) load of tablecloths are
presented in Tables 64 and 65 respectively. From these tables it can
be seen that the concentration of solids and TOC decreases with the
second flush and increases dramatically after the addition of supplies.
The total solids and TOC concentrations then decrease again followed by
another increase in TOC with the high suds cycle. The concentrations of
each then decrease gradually with each succeeding rinse. This pattern
was followed for all the articles sampled.
From these tables it is evident that linen wastewater is not nearly as
potent as industrial laundry wastewater. It appears to be of about
the same level of contamination as uniform laundry wastewater. It may
be noted that linens are utilized for considerably different purposes
than shop towels or uniforms. The linens washed at this laundry are
utilized mainly by food handling industries; restaurants or butchers,
and for restroom cleanliness, i.e. continuous towels. Thus the type of
soil present in linen items is considerably different than that in
uniform or industrial items. Even though the levels of gross chemical
properties for uniform and linen laundry wastewater may appear relatively
the same, i.e. TOC, total solids, suspended solids, the wastewater treat-
ment characteristics and chemical properties of the two wastewaters may
be considerably different. These tables also demonstrate extreme
variability of wastewater quality even for linen laundries. The data
obtained from the analyses of the machine dumps were uspd to compute the
kgs of TOC and total solids in the wastewater per 100 kgs of articles
washed, including the supplies. The results of these computations are
presented in Table 66 along with all the other similar analyses presented
in the industrial and uniform laundry sections. All data obtained from
this survey and the uniform survey are presented in this table, while
only the ranges for the industrial items are given. Complete data for
all linen dumps sampled and analyzed may be found in Table C-3 of
Appendix C.
From this table it can be seen that there is not much difference in the
amounts of TOC and total solids generated by the different linen articles.
The kitchen towels contribute the most to the wastewater contamination.
In comparison with the industrial articles, it can be seen that the
quantity of TOC and total solids generated by 100 kgs of linen or
continuous towels is only about 10% of that generated by the wipers.
This, in conjunction with the low proportion of flow generated by the
linen washing machines at the Roscoe plant demonstrates what a minor
contribution the linen flow makes to the pollutional load of the final
sewer discharge. The effect of the linen wastewater on the plant
discharge is minimal. Generally, this table shows that synthetic
shirts and pants and uniforms contribute about the same amount of TOC
and total solids to the wash water as kitchen towels and heavy soil
table linens. The uniforms contribute more TOC and solids than "do the
148
-------
TABLE 64
VARIATION OF UASTEWATER QUALITY I/IT!I
WASHING OPERATION FOR A 364 KG LOAD OF KITCHEN TOWELS
Operation
Flush
Flush
Suds
Rinse
High Suds
Bleach
Rinse
Rinse
Rinse
Rinse
Sour
TOG
1,296
480
3,030
448
1,140
600
164
92
44
156
10
Total
Solids
(rag/1)
3,211
1,083
8,004
3,098
2,944
2,115
714
426
334
343
337
PH
(Units)
7.5
8.6
12.6
12.3
12.05
10.8
10fl
9.7
9.4
9.0
4.6
Suspended
Solids
(mg/1)
--
.360
1,895
380
745
430
110
102
43
85
90
149
-------
TABLE 65
VARIATION OF WASTEWATER QUALITY WITH
WASHING OPERATION FOR A 136 KG LOAD OP TABLECLOTHS
Operation
Flush
Flush
Break
Carryover
Suds
Rinse
Bleach
Rinse
Rinse
Rinse
Rinse
Sour
TOC
(mg/1)
445
435
2,555
1,550
2,012
740
952
329
268
150
107
54
Total
Solids
(mg/1)
1,034
865
9,548
6,341
6,638
2,600
2,726
1,276
668
483
374
801
pH
(units)
5.85
6.4
12.3
12.35
12.0
11.8
11.9
11.25
10.7
10.1
9.9
4.5
150
-------
TABLE 66
ESTIMATED WASTE LOAD QUANTITIES
FROM VARIOUS LAUNDERED ITEMS
Article Kgs
Laundered Kgs of
Shirts
Print Rags
Uniforms
Shirts
Pants
Coveralls
Uniforms
Entrance Mats
Continuous Towels
Table Linen
Table Linen
Kitchen Towels
Kitchen Towels
Kitchen Towels
Table Linen
Napkins
Table Linen
Print Wipers
Dust Mops
Machine Wipers
TOC per 100
Article Laundered
2.28
11.54
2.47
2.53
2.34
1.73
0.87
9.94
1.6
0.5
0.9
2.85
1.45
2.3
2.44
0.8
1.6
18-42
12-13
24-45
Kgs Total Solids/100
Kgs Article Laundered
11.36
20.91
6.89
9.23
8.90
6.91
6.80
22.89
6.8
2.35
4.9
9.27
4.95
8.9
8.08
4.4
6.2
48-66
40-41
65-73
151
-------
lighter soil napkins and continuous towels. Neither type of article
contains near the level of contamination of the industrial laundry
articles.
A series of suspended solids analyses on each individual dump of a load
of kitchen towels indicated that 1.1 kgs of suspended matter/100 ke;s of
kitchen towels washed were produced. A similar series of analyses on
a load of print wipers demonstrated that about 5.8 kgs of suspended
solids/100 kgs of print wipers washed were produced. Thus the non-
industrial articles are contributing only about 1/5 of the suspended
solids generated by an equivalent weight of wipers. A similar set of
analyses for a load of coveralls also measured 1.1 kgs of suspended
solids per 100 kgs of coveralls. Thus the uniform wastewater generated
an amount of suspended matter comparable to the kitchen towels, again
demonstrating that there is not a gross difference between the amount
of organic solid contaminants added to the wash water by uniforms and
linens. Consequently, one would expect that the variability of linen
wastewater at the sewer discharge point would be similar to that for
uniforms (see Figure 20).
BENCH SCALE FLOTATION TESTING OF LINEN LAUNDRY WASTEWATER
The linen grab samples obtained were composited in equal volumes to
simulate a representative sample of linen waste. A series of grab
samples from each washing cycle of a load of kitchen towels was also
composited in proportion to the volume of water utilized per wash opera-
tion to simulate a linen sample. Several days after obtaining the
samples, they were subjected to chemical treatment tests to determine
what dosages and chemicals were required to promote floe formation
to make the waste amenable to flotation. The waste characteristics
of the two samples are presented in Table 67. It was found that
CaCl2*2H20 treatment was ineffective on the two composite samples.
However, alum and sulfuric acid proved to work quite well for the
composited grab samples. By adjusting the initial pH to 9.5 with
sulfuric acid followed by 800 mg/1 alum and 2 mg/1 Purifloc N-ll
(nonionic polyelectrolyte), a good floe was formed. The kitchen towel
composite needed no pH adjustment as 800 mg/1 alum and 2 mg/1 Purifloc
N-ll formed a good floe. The final pH's of the treated samples were
5.0 to 5.2.
Two bench scale flotation tests were performed on the composited grab
samples obtained from the linen discharges in the trench. The results
of these are presented in Table 68. It can be seen that the results
were not too good for this particular sample. Increasing the alum
dosage improved the results somewhat. The flotation effluent was a
cloudy white and was slightly better than had been experienced
for uniforms (see Table 57).
152
-------
TABLE 67
WASTE CHARACTERISTICS OF LINEN
COMPOSITES OF MAY 20, 1971
Analysis
Ul
Total Solids, mg/1
Suspended Solids, mg/1
pH, units
Silica as Si02, mg/1
Alkalinity as CaC03, mg/1
TOG, mg/1
Volatile Total Solids, mg/1
Volatile Suspended Solids, mg/1
Grease, mg/1
Composite of
Linen Grab Samples_
2,160
346
11.3
510
665
548
1,106
330
203
Composite of Kitchen
Towel Grab Samples
1.752
288
10.2
-------
TABLE 68
BENCH SCALE FLOTATION TESTS CONDUCTED
ON LINEN COMPOSITE SAMPLE OF MAY 20, 1971
Chemical Treatment
Recycle Rate, Z
Rise Rate, mpm
Detention Time, min
Scum Volume, 1/1000 1
Sludge Volume t I/1000 1
Effluent Quality
PH
Suspended Solids, mg/1
Z Suspended Solids Removal
Total Solids, mg/1
Volatile Total Solids, mg/1
TOC, mg/1
Z TOC Removal
Grease, mg/1
Z Grease Removal
Test No. 1
343 mg/1 H2S04
800 mg/1 Alum
2 mfe/1 Purifloc N-ll
50
0.09
8
40
Trace
5.2
236
31.8
1,853
506
215
62.5
98
51.8
Test No. 2
294 mg/1 H2S04
1,200 mg/1 Alum
2 mg/1 Purifloc N-ll
50
0.24
8
50
5.6
129
62.5
1,798
450
153
72
154
-------
The effluent from test number two was filtered through diatomaceous
earth to determine what final effluent quality might be expected. These
results are presented in Table 69. Compared to the final rinse qualities
of various linen articles laundered in the survey, it is apparent that
this treatment produced a good quality effluent. The final rinses of the
linen wash load samples had between 85 and 440 mg/1 suspended solids,
and 23-229 mg/1 TOG, and 300-824 mg/1 total solids. The bench scale
diatomaceous earth treated flotation effluent thus compares favorably
with the final rinses except for the parameter of total solids. Thus,
alum coagulation and DE filtration appeared very promising for the
Roscoe linen wastewater.
Prior to the start of full scale linen laundry wastewater treatment in
1973, fresh linen samples were obtained on January 10, 1973 for more
bench scale test work to insure that the treatment characteristics of
the linen wastewater had not changed. Two 11 liter(3 gals.) composite
samples .of linen waste were obtained by compositing wastewater from one
entire wash cycle of one 3b4 kg (800 Ib) washer. The two samples repre-
sented wastewater from washing tablecloths and kitchen towels respec-
tively. Bench scale chemical treatment tests were performed in the
field to insure that the chemical treatment characteristics would be
representative of what actually happens in a treatment system.
Various combinations of sulfuric acid and alum were tried on the fresh
samples of linen waste obtained on 1/10/73. In all cases, treatment was
poor. Best results obtained when treating with alum were achieved with
no acid and 3,000 mg/1 alum. This was considerably different than what
had been determined in 1971. Treatment with calcium chloride and
Purifloc A23 produced better results than alum. About 1,000 mg/1 ~
CaCl2*2H20 was the optimum dosage for the table cloth waste and 2,000
mg/1 was the optimum dosage for the kitchen towel wastewater. Five mg/1
Purifloc A23 was needed to form a large strong floe. Chemical treatment
tests were performed again on the same samples two days later at the
Environmental Sciences Division laboratory. At that time, treatment
with acid and alum appeared to be somewhat improved while treatment with
calcium chloride appeared to be slightly less effective. Chemical
treatment tests were again performed on the same waste samples on
January-17, 1973. The aged tablecloth waste could now be treated with
alum quite well. Treatment of the kitchen towel waste with acid and
alum appeared to be somewhat better than before, but the improvement was
not as great as with the tablecloth waste. Treatment of the aged waste
with calcium chloride appeared to be the same or slightly worse than
treatment of the fresh waste. It was now apparent that the age of the
waste significantly affected the chemical coagulation and flocculation
properties of the wastewater.
A comparison of the analysis of the January 10, 1973 samples with the
analyses of linen wastes tested previously is shown in Table *0. The
initial work on treating linen wastewater was performed on 8 samples
155
-------
TABLE 69
WATER QUALITY OF DIATOMACEOUS EARTH
FILTERED LINEN FLOTATION EFFLUENT AS
COMPARED TO LINEN FINAL RINSE QUALITY OF
MAY 20, 1972
Analysis Bench Scale Effluent Final Rinse
PH 5.6 8.6-10.4
Suspended Solids, rag/1 16 85-440
% Suspended Solids Removal 87.7
TOC, mg/1 74 23-220
% TOC Removal 51.6
Total Solids, mg/1 1,499 300-824
Volatile Total Solids, mg/1 335
Volatile Suspended Solids, mg/1 5
156
-------
TABLE 70
COMPARISON OF LINEN WASTEWATERS
OBTAINED ON VARIOUS DATES AND FROM VARIOUS LAUNDRIES
Type of Work Kitchen Table Kitchen Table
Cosmo- Towels Cloths Towels Cloths
Laundry American Linen Supply politan Roscoe GC Roscoe GC Roscoe GC Roscoe GC
Date 1969 1969 1971 1971 1973 1973
Min. Max. Avg.
PH 10.3 11.2 11.1 10.2 11.3 11.4 11.6
Alk., mg/1 CaC03 500 925 679 525 — 665 1525 1225
TS, mg/1 1973 3663 2675 2386 1752 2160 6514 3054
TVS, mg/1 1468 1630 1549 — — 1106 4014 1280
TNVS, mg/1 — -- — — — 1054 2500 1774
SS, mg/1 500 1474 736 611 288 346 1530 340
VSS, mg/1 — — — — — 330 1330 270
NVSS, mg/1 — — — — -- 16 200 70
COD, mg/1 2125 5113 3057 2428
TOC, mg/1 — — — — — 548 2150 530
Si, mg/1 as Si02 — — — — — , 510 . 940 ^ 685 ,
Soluble Solids, mg/1 1725 2038 1837 — 1464"1" 1814 4984 2714
Vol. Sol. Solids,rag/1 964 991 978 — — 776 * 26841 10101
Grease, mg/1 — — 883 558 — 203 1220 276
Sol. COD, mg/1 1173 2590 1649 767
Sol. TOC, mg/1 — — — — — — 900 330
1 By Calculation
-------
obtained from American Linen Supply (Milwaukee) and one sample from
Cosmopolitan Laundry (Chicago) in 1969 (2). The American Linen Supply
samples were tested within three hours of sampling. The Cosmopolitan
sample was tested the day after sampling. Best results were obtained
when treating with sulfuric acid (240 to 540 mg/1) and alum (500 to 700
mg/1 as Al2(504)3*18H20). In May 1971, a composite sample of kitchen
towel waste and one of tablecloth waste were obtained from the Roscoe
Garden City Laundry. The tablecloth composite was tested several weeks
after sampling. It was found that 300 mg/1 sulfuric acid, 800 mg/1
alum and 2 mg/1 Purifloc Nil were effective in treating this sample.
The tests conducted on January 10, 1973 demonstrated that alum was not
an effective coagulant for the Roscoe Garden City linen wastewater even
though the previous cited test work for other laundries indicates that
acid-alum chemical treatment was effective for fresh linen wastewater
samples. It is not known what causes this difference, but it is
suspected that it is related to differences in supplies. For fresh
Roscoe linen wastewater, calcium chloride again proved to be the effec-
tive chemical coagulant. Thus when sampling linen laundries for the
purpose of doing bench test work, it is necessary to perform the testing
as soon as possible and to take into account the effects of the laundry
wash formula on the treatment techniques. A similar set of tests for
industrial laundry wastewater indicated no changes in the recommended
chemical treatment techniques. Wastewater age did not appear to affect
the industrial samples.
It may be noted from Table 70 that there are significant differences
between the wastewater chemical analyses presented. The Roscoe kitchen
towel sample is significantly higher than any of the other samples in
total solids, grease, soluble solids, suspended solids, and alkalinity.
This could be one reason for the differences observed in the testing.
Subsequent analysis of Roscoe linen wastewater never provided linen
wastewater this strong again. However, calcium chloride treatment of
weaker Roscoe linen wastewater proved very effective as shown later
in this report, thus indicating that waste age influences the treata-
bility of the wastewater.
Bench scale flotation tests were performed on the two samples of
January 10, 1973 using calcium chloride treatment to determine the
effect of this treatment on effluent quality. The results of these
tests are listed in Table 71. The addition of calcium chloride to
linen waste causes a white precipitate to form. This precipitate
causes a great increase in the suspended solids content resulting in a
greater scum volume and slower rise rate than one might expect from the
suspended solids content of the untreated waste. It should be noted,
however, that there is a significant reduction in soluble solids.
158
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TABLE 71
RESULTS OF FLOTATION TESTING OF
LINEN WASTES OF 1/10/73
Waste Treated
Test No.
CaCl22H20 added, mg/1
Purifloc A23 added, mg/1
A12(S04)3'18H20 added, mg/1
Flocculation time, mln
Recycle Rate, %
Rise Rate, mpm
Scum Vol, 1/1000 1
Sludge Vol, 1/1000 1
Detention time, min
Effluent:
Grease, mg/1
TOC, mg/1
Suspended Solids, mg/1
Total Solids, mg/1
Total Volatile Sol, mg/1
Total Non-Vol Sol, mg/1
Soluble Solids, mg/1
Turbidity, FTU
Silica, mg/1 as Si02
% Reduction in:
Grease
TOC
Suspended Solids
Total Solids
Soluble Solids
Silica
Kitchen Towel Composite
KT-1
2500
10
—
1
50
0.08
202
trace
10
•»•*
492
97
3816
1150
2666
3719
62
270
_ ..
77
94
41
25
71
KT-2
2500
10
—
1
100
0.09
210
trace
10
33
456
81
3553
1058
2495
3472
53
244
97
79
95
45
30
73
KT-3
2000
10
—
1
50
0.04
278
trace
10
__
552
198
3764
1183
2581
3566
130
335
__
74
87
42
28
64
KT-4
2500
5
—
1
50
0.06
22j
trace
10
39
498
65
3866
1158
2708
3801
45
270
97
77
96
41
24
71
Tablecloth
Composite
TC-1
1000
2
—
1
50
0.07
75
trace
10
__
276
261
2528
668
1860
2267
230
450
__
48
23
17
16
34
TC-1
1000
0
1000
1
50
—
112
trace
10
96
240
294
2710
588
2122
2416
190
360
65
55
14
11
11
47
By Calculation
159
-------
The results of the flotation of the kitchen towel waste were quite good
affecting significant reductions in TOG, suspended solids and grease,
whereas the tablecloth wastewater did not treat as well. An increase
in calcium chloride dosage resulted in decreases in effluent TOC and
suspended solids. The optimum calcium chloride dosage thus appeared
to be 1,900 mg CaCl2/l- It was concluded that calcium chloride should
now be the chemical utilized in the linen wastewater treatment operation.
Afterfloc tests similar to those performed with industrial laundry waste-
water were also performed with the linen laundry wastewater. The same
procedures were followed. The results of the testing appears in Table
72. The testing showed ^that a ten minute interval between the chemical
additions prevented the formation of afterfloc. Therefore, it was
decided to leave the chemical addition points in the equalization pit
(CaCl2) and the flocculator (polyelectrolyte). This provides approxi-
mately sixty minutes between chemical additions insuring against any
afterfloc formation. The treatment concept decided upon for the linen
laundry wastewater treatment portion of this project was unchanged from
the scheme utilized for uniform laundry wastewater treatment.
LINEN LAUNDRY WASTEWATER TREATMENT SYSTEM EFFLUENT QUALITY
The linen laundry wastewater treatment system was operated from January
20, 1973 to March 29, 1973 during which a total of twenty distinct tests
were performed utilizing linen wastewater. On three days, two sets of
samples were obtained for two tests performed when a separate and dis-
tinct break occurred in the run, such as the equalization pit running
dry. The equalization pit was used for all tests, and again the
chemical dosage, surface overflow rate and other parameters were changed
to study the effect of independent variable changes on effluent quality.
Linens were trucked in from various laundries to provide enough soil
for the treatment system. Composite samples of vacuum filtrate, scum,
flotation effluent, raw wastewater, and DE effluent were obtained for
all tests during the entire length of the operation. Only one set of
heavy metal determinations was made, as it was felt that this was not
a significant problem for linen wastewater. A wastewater reuse test
was performed on April 19, 1973 in a manner similar to the other two
wastewater reuse tests conducted.
Operating data for the above mentioned tests are presented in Table C-10
of Appendix C. Tables C-ll and C-12 of this same appendix present the
vacuum filter operating data and effluent quality analyses for this same
test work, respectively. No significant relationships between the
variables of flotation effluent suspended solids, grease, surface
overflow rate, calcium chloride dosage, mass loading, or suspended
solids and grease removal efficiencies were found to exist. Upon exami-
nation of the flotation effluent quality data for all tests, it is
evident that no such relationships are necessary, as only one flotation
effluent suspended solid concentration is greater than 200 mg/1 and only
160
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TABLE 72
THE EFFECT OF VARYING THE TIME INTERVAL BETWEEN
CALCIUM ADDITION AND POLYELECTROLYTE ADDITION ON THE FORMATION
OF AFTERFLOC ON LINEN LAUNDRY WASTEWATER
Si, mg/1 as Si02
iime Interval
Turbidity, FTU
Initial After 20 hrs
1/2 min
1 1/2 min
3 1/2 min
10 min
120
65
43
37
270
170
70
38
Initial
410
375
338
300
After
Total
418
375
342
300
4 days
Supernatant
268
300
285
285
overnight
After Floe
246
234
225
much, formed quickly
some, formed overnight
some, formed overnight
none overnight; trace
formed later
none overnight; trace
formed later
Test Procedure: 2500 mg/1 CaCl2'2H20 added to waste, mixed, then allowed to stand 1/2, 1 1/2,
3 1/2, 10 rain and overnight. A23 was then added, the waste mixed 1 minute
and allowed to settle. The hanging floe in the supernatant was removed by
filtration through 541 paper. Filtrate was allowed to stand to observe
afterfloc formation.
Results: 1. The amount of afterfloc formed is indicated by the increase in turbidity after storing
overnight.
2. The silica content of the samples did not change appreciably over a period of 4 days.
There was no evidence of scale forming on the container glass walls.
3. After the afterfloc settled, the supernatant contained significantly less silica
indicating that the afterfloc may be a calcium silicate material.
-------
three flotation effluent greases exceed 100 mg/1. All tests conducted
provided good results regardless of operating conditions. This is an
acceptable discharge for all municipal sewer ordinances investigated
during this project, as shown in Appendix A. It is obvious that the
performance of the flotation unit was adequate under a wide variety
of conditions. The higher flotation effluent concentrations of suspended
solids and grease could not be attributed to high overflow rates or to
low calcium chloride dosages, as other runs at equivalent calcium
chloride dosages and overflow rates produced adequate results.
The maximum flov? that could be obtained from the linen return pump during
this testing was 515 1pm (136 gpm). It is felt that due to the nature
of the wastewater, the flotation tank can operate at least at the same
flowrate as it could for uniforms and that 75% recycle provides plenty
of solids separation. Based on raw wastewater suspended solids analyses,
50% recycle would be adequate utilizing the rule of thumb that 100%
recycle is required for every one half percent solids. Therefore, 50%
recycle is plenty for linen wastewater of the characteristics of this
study. It may be noted from Table C-12 that the vacuum filtrate was
always of excellent quality containing generally less than 100 mg/1
suspended solids. The vacuum filtrate of March 28, 1973 contained only
38 mg/1 grease. Thus, the vacuum filtrate is suitable for discharge
to the sewer. It does not have to be recycled back to the rapid mix
chamber. This further increases the capacity of the flotation unit by
about 40 1pm (10 gpm) since the filtrate flowrate was generally 75 to
100 1pm (20-25 gpm) and the vacuum filter only had to be operated one
half of the time of the flotation unit. Therefore, based on an optimum
overflow rate of 98 Ipm/sq ft (2.4 gpm/sq ft) and 50% recycle and not
recycling the vacuum filtrate, the flotation tank at the Roscoe laundry
can be rated at 659 1pm (174 gpm) for linen laundry wastewater. The nine
minute detention! time available in the flotation tank was adequate for
linen wastewater as evidenced by the effluent quality data. Therefore,
a large flotation unit is not required.
Table 74 presents average effluent analyses and removal percentages
for BOD, TOC, suspended solids and grease for the 20 tests performed.
The 95% confidence limits about the sample means are also presented to
demonstrate the range of effluent quality obtain. Thus, it can be
expected that the parameter under consideration will fall within the
range specified 95% of the time. The flotation effluent grease 95%
upper confidence limit is 90 mg/1. For BOD and suspended solids, this
same statistic is 271 mg/1 and 133 mg/1 respectively. It is evident
that even the worst quality water obtained from the flotation unit
reduced the suspended solids, grease, and BOD to levels acceptable for
sewer discharge. The DE filter reduced these values to even lower
levels: 202 mg/1 BOD, 90 mg/1 suspended solids, and 62 mg/1 grease.
Based on these results, the flotation effluent obtained from the linen
wastewater treatment at the Roscoe plant is suitable for sewer discharge
and would incur no sewer surcharges for BOD or suspended solids.
162
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TABLE 73
LINEN WASTEWATER TREATMENT
EFFLUENT QUALITY DATA
Parameter
Raw Wastewater
BOD, mg/1
TOG, mg/1
Total Solids, mg/1
Suspended Solids, mg/1
Grease, mg/1
Flotation Effluent:
BOD, mg/1
TOC, mg/1
Total Solids, rag/1
Suspended Solids, mg/1
Grease, mg/1
DE Effluent:
BOD, mg/1
TOC, mg/1
Total Solids, mg/1
Suspended Solids, mg/1
Grease, mg/1
Flotation Percent Removal:
BOD, mg/1
TOC, mg/1
Suspended Solids, mg/1
Grease, mg/1
System Percent Removal:
BOD,, mg/1
TOC, mg/1
Suspended Solids, mg/1
Grease, mg/1
No. of
Observations
20
20
20
20
20
20
20
20
20
20
9
9
9
9
9
20
20
20
20
9
9
9
9
Mean 95%
Value Confidence Limits
501 331-672
410 311-510
4,061 2,418-5,705
852 384-1,320
207 163-251
222 173-271
176 145-208
3,752 3,130-4,374
101 69-133
69 48-90
155 108-202
120 89-150
3,521 2,636-4,405
59 29-90
47 32-62
42.5 29.7-55.2
50.7 40.9-60.5
74.1 62.1-86.1
62.1 50.7-73.4
55.6 40.3-70.8
64.5 52.3-76.7
81.8 86.7-97.1
71.7 55.1-88.2
163
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The linen wastewater reported upon in Table 73 is generally an average
linen wastewater in terms of total solids, alkalinity, and suspended
solids, but it appears to have a lower BOD and grease content than
other linen wastewaters reported on in the literature (compare reference
2 and Table 67). This leads to some concern that the unit will not
perform adequately if the concentrations of these parameters were
higher. The system only removed an average of 56% of the BOD and 72%
of the total grease available. Thus those linen laundries with 1000
mg/1 BOD and 500 mg/1 hexane soluble contents may not get the desired
effluent quality. In this test work, raw wastewater BOD's of 750 mg/1
were regularly handled with no degradation of effluent quality, and
grease concentrations of up to 350 mg/1 were removed to acceptable
levels. Generally, the efficiency of a treatment unit will increase
with higher influent concentrations up to a certain point. It is
expected that this would also be true here. In any case, those linen
laundries with a relatively weak waste load can do an effective treat-
ment job for sewer discharge with only a flotation unit; whereas laun-
dries with stronger wastewater, such as discussed previously, will
require DE filtration of the flotation effluent. Average suspended
solids concentrations of 850 mg/1 require flotation separation prior to
DE filtration to prevent rapid plugging of the filter. It is anticipated
that difficulty in meeting local sewer codes with DE filter effluent will
only be a problem for linen laundries with very strong wastewaters.
At what concentration level this might occur, cannot be determined from
the data obtained in this study.
Table 74 presents the proportions of the type of linen soil washed on
each test day. The linens were classified as to soil by the laundry
personnel. The heavy soil items were generally aprons and kitchen
towels. Medium soil items were generally continuous towels and assorted
table linen. White sheets and napkins, as well as other miscellaneous
items made up the light soil. It can be seen that the wash volume
laundered during this test work generally contained more light soil.
This is probably one of the main reasons for the low organic content of
the wastewater encountered here. The type of wastewater generated by
the soil mix outlined in Table 74 can be satisfactorily treated, unless
the definition of soil type differs radically throughout the industry.
The other analyses in Table C-12 of Appendix C indicate that 65^ of the
time, the flotation effluent pH was less than 10 and required no
neutralization. On one day, it was 12.7, but this appears to be exces-
sive compared to what is normally obtained. The phenolphthalein
164
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TABLE 74
TYPE OF LINEN SOIL HANDLED BY
THE WASTEWATER TREATMENT SYSTEM FOR EACH TEST DAY
Test Day
'2/20/73
2/21/73
2/22/73
2/23/73
2/27/73
2/28/73
3/1/73
3/14/73
3/15/73
3/16/63
3/20/73
3/21/73
3/22/73
3/23/73
3/28/73
3/29/73
4/19/73
AVERAGE
Light Soil
Percentage
62
62
44
53
32
48
41
39
26
32
42
50
31
33
30
29
33
40
Medium Soil
Percentage
19
19
22
32
45
26
36
43
52
36
46
38
44
33
50
47
42
37
Heavy Soil
Percentage
19
19
'34
15
23
26
23
18
22
32
12
12
25
34
20
34
25
23
165
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alkalinity of the flotation effluent was almost always 100 to 120 mg/1
indicating very little acid neutralization of linen laundry wastewater
effluent will normally be required. Thus neutralization costs can be
expected to be low.
Analysis for heavy metals of the linen laundry wastewater did indicate
trace amounts of copper, lead, zinc, and nickel. The only problem area
appeared ,to be lead which was measured at 0.7 mg/1. However, it is felt
that most of the heavy metals measured probably came from sources other
than .the linen wastewater especially noting the character of the indus-
trial laundry washwater. One of the linen washing machines was used
to launder wipers during this test period when the treatment system was
not being operated. So it is possible that this action could leave
heavy metal residuals behind in the wash wheel and the water trench
receiving the dump. The equalization pit may also have contributed some
heavy metals. At any rate, the treatment system removed all the heavy
metals measured to acceptable levels. If the linens did contribute the
metallic components of the wastewater, the treatment method employed
is capable of removing them.
For linen wastewater treatment, the treatment system performed very
consistently over a wide range of operating conditions, as demonstrated
by Table 74.! When the DE filter was operated, effluent grease never
exceeded 87 mg/1, BOD never exceeded 274 mg/1, and suspended solids
never exceeded 115 mg/1. This indicates that an effluent always meet-
ing sewer codes is generated by the treatment system. The radical
changes in removal efficiencies and effluent quality experienced for the
uniform and industrial laundry wastewater treatment were not demonstrated
for the linen laundry system. Evidently, because the linen laundry
wastewater is weaker and does not contain as many materials, the treat-
ment mechanisms are less complex and do not cause as much unpredicta-
bility in waste treatment techniques. The linen wastewater tended to
have lower suspended solids, TOG and alkalinity than the uniform waste-
water, as well as fewer heavy metals. The linen wastewater contained
more BOD, while grease and total solids were about the same. The higher
BOD values for linen wastewater is probably a function of heavy metal
toxicity, as the uniform wastewater contains large amounts of toxic
materials. The cause of the differences in the wastewater treatment
results may well lie in one of the above observations.
LINEN LAUNDRY WASTEWATER TREATMENT SYSTEM OPERATIONAL RESULTS
No mechanical difficulties were encountered in treating linen laundry
wastewater. All components of the treatment system worked effectively
during the test period. The one hour equalization period available
was adequate for linen wastewater. The flotation unit concentrated the
incoming wastewater suspended solids to 0.25% to 4.12%. This entire
range of solids concentrations were found to be suitable for vacuum
filtration. Generally, 0.25% suspended solids is too thin for vacuum
166
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filtration, but it did not present a problem in this instance. Adequate
linen waste clarification was achieved at overflow rates of 95 Ipm/sq ft
(2.3 gpm/sq ft) and 75% recycle. However, because of reasoning presented
previously, the flotation unit is rated at 659 1pm (174 gpm) at a 50%
recycle ratio.
Calcium chloride chemical treatment is effective over a wide range
of dosages, 800 to 2,500 mg/1. However, 1,250 mg/1 generally produced
a large stable floe, strengthened by 2 mg/1 polyelectrolyte.
Vacuum filter blinding is not a problem for linen sludge dewatering.
The cake readily picked up and dewatered to 25% solids with little
difficulty. At times, the cake would only dewater to 15% solids, for
which the reason is not clear. The majority of the time, however, 20%
to 25% cake solids were readily attainable. The cake itself was pure
white and was not as greasy as uniform or industrial laundry wastewater
sludge. This fact prevents it from liquifying to a great extent from
the Moyno pump action. Consequently, it would be possible to handle
this sludge as a solid fill material. It was not handled as such
during this project, as commitments had already been made to a liquid
hauler. This could lead to significant costs savings in linen laundry
treatment. However, this sludge is putrescible, whereas the uniform
and industrial sludges were not. Consequently the sludge must be
hauled away on a regular basis, to prevent serious odor problems. The
filter yield obtained was proportional to scum suspended solids, as
these two parameters provided a 0.63 correlation coefficient, a correla-
tion significant at the 95% level of confidence. The vacuum filtrate
was of excellent quality as previously noted. The 10.22 sq m (110
sq ft ) vacuum filter used here only had to be operated 1/4 to 1/2 the
time of the treatment system operation to dewater all the sludge.
Consequently, a vacuum filter one half the size of this one could be
employed for this linen waste.
The DE filter operation was very satisfactory for treating flotation
effluent. Differential pressure buildups of 0.1 to 0.3 kg/sq cm/hr
(1 to 3 psi/hr ) were obtained using no body feed. In fact, the same DE
was reused several times and still no great surges in differential
pressure increases were obtained nor was a degradation of effluent
quality evident. The DE filter would need to be precoated only once
per shift to provide a good wastewater effluent.
The optimum linen laundry wastewater treatment system operating
conditions determined from this study are presented in Table 75. All
parameters presented in this table are as previously discussed.
Table 76 presents the operating results of the system. The scum
volumes were estimated from the vacuum filtrate flow and the proportion
of time the vacuum filter operated. A five to ten fold sludge volume
reduction takes place in the vacuum filtration dewatering step,
167
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TABLE 75
OPTIMUM OPERATING CONDITIONS
FOR THE LINEN LAUNDRY WASTEWATER TREATMENT SYSTEM
Flotation Overflow Rate 98 Ipm/sq m
Flotation Recycle 50%
Flotation Detention Time 9.5 minutes
Equalization Time 1 hour
CaCl2 Dosage 1,250 mg/1
Polyelectrolyte Dosage 2 mg/1
Detention Time Between Two Chemical Additions 1 hour
Vacuum Filter Cycle Time 5.5 minutes
Vacuum Filter Pickup Time 0.8 - 1.2 minutes
Vacuum Filter Vacuum Level >25 cm Hg»
DE Filter Hydraulic Loading 18 Ipm/sq m
DE Precoat 0.74 kg/sq m
DE Body Feed None
168
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TABLE 76
GENERAL OPERATING RESULTS
OF THE LINEN LAUNDRY TREATMENT SYSTEM
Flotation Scum Volume 40 - 60 1/1,000 1 raw flow*
Sludge Volume 4-8 1/1,000 1 raw flow
Sludge Moisture 75% - 85%
Filter Yield 7-17 kg/sq m/hr
r>
Filter Blinding 0%
Vacuum Filtrate Flow 70 - 95 1pm
DE Pressure Buildup 0.15 - 0.30 kg/sq cm/hr
* Estimated from filtrate flow and vacuum filter time.
169
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producing a relatively dry cake, even at low scum solids concentrations.
Sludge volumes were calculated from an assumed 1.077 gm/cc (9.0 Ibs/gal.)
density. The DE pressure buildup occurring in the majority of the tests
were minimal. Thus a DE filter loaded at 18 Ipm/sq m (0.45 gpra/sq ft)
could be operated for a full shift without backwashing.
LINEN LAUNDRY WASTEWATER TREATMENT SYSTEM OPERATING COSTS
Table 77 presents the linen laundry waste treatment operating costs,
as obtained from the demonstration unit. The chemical coagulant cost
is based upon adding 1,250 mg/1 CaCl2 and 2 mg/1 anionic polyelectrolyte.
Neutralization costs are based on neutralizing 100 mg/1 effluent alka-
linity as calcium carbonate with sulfuric acid. Power costs and
material and maintenance costs are the same as discussed in the previous
two sections. Diatomaceous earth costs are figured on the addition
of 72 mg DE per liter (0.6 lbs/1000 gal.) of wastewater. No body feed is
provided. Sludge disposal costs are based on hauling 6 liters of sludge per
1,000 liters of wastewater treated at 1.2c/liter (4.5c/gal.). The cost is
one third of this if the cake is hauled away as a solid.
Capital costs are based on the same conditions as previously discussed
with the system rated at 659 1pm (174 gpm). For two shift operation,
the amortized costs are 4.0c/cu m (15C/1000 gal.) and 2.6c/cu m
(lOc/1000 gal.) for a three shift operation. The total operating
cost is then 40.1c/cu m ($1.52/1000 gal.) at the Roscoe plant
compared to twice this amount for industrial laundry wastewater.
The costs could be reduced to 32c/cu m ($1.21/1000 gal.) if the cake is
hauled as a solid and coagulants are bought in bulk.
Linen laundry wastewater costs much less to treat than uniform or
industrial laundry wastewater. The costs are still considerable,
however. At 32c/cu m ($1.21/1000 gal.), this would raise the cost of
linen laundering by 0.9c/kg (0.4c/lb). It may be noted that any
surcharges for BOD and suspended solids will be done away with by
wastewater treatment, but this is not a large savings as indicated by
the industrial waste survey (Appendix A). Approximately 2.6c/cu m
(IOC/1000 gal.) may be recovered by eliminating this charge. It would
not be economical to treat this wastewater strictly on the basis of
surcharge reduction. However, linen laundries will find themselves put
in a position forced to treat wastewater in many cases due to alkalinity
and hexane soluble limitations of municipal sewer ordinances.
Waste treatment costs will vary considerably dependent on the type of
soil, laundry location and size, sludge handling methods, etc.
Therefore, thf.se costs cannot be taken as absolute, but are only
directly apnlicable to the demonstration treatment system. It should
be possib1 :• obtain some idea of wastewater treatment costs by
extrapolaci the data presented here if the particular wastewater
characteristic^ are known.
170
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TABLE 77
OPERATING COSTS FOR LINEN LAUNDRY WASTEWATER
TREATMENT IN c/CUBIC METER
Coagulation Chemicals 14.0 (10.6)a
Sludge Disposal 7.1 (2.4)b
Neutralization 0.8
Power 2.6
Material and Maintenance 6.6
Amortization - 20 yrs @ 6% 7.7
Diatomaceous Earth 1*3
Total Cost for Sewer Disposal 40.1 (32.0)ab
a If chemicals bought in bulk.
b If hauled as a solid waste at $3.92/cu m ($3.00/cu yd.)
171
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LINEN LAUNDRY WASTEWATER REUSE TESTING
The April 19 DE effluent was used in a wastewater reuse test to wash a
182 kg (400 Ib) load of red table linens. The effluent from the waste
treatment system was pink, which does not harm the red items. Dye is
a definite problem generally, as solids separation techniques will not
remove it. Any laundry using a lot of dye will find limited application
for reusing wastewater for white items. This reuse test was performed
in a manner similar to those discussed previously. Samples were obtained
from each dump of two loads of table linen, one washed with effluent and
one with softened city water. Each dump was analyzed for pH, TOG and
total solids with the results reported in Table 78.
In almost all analyses, the reused water contains more alkalinity, TOC,
and solid material than the city water, as expected. The final rinse
of the table linen is almost the exact same quality as the DE effluent
indicating that the majority of the contaminants have been flushed from
the linens. Thus, no solids appear to be depositing themselves in
the laundered articles.
Based on the differences in the total solids analyses, the reused water
dumped 2.25 kg (4.96 Ibs) more total solids than the city water laundered
articles. All the total solids of the wash load discharge into 6,100
liters (1600 gal.) of wash water. The composited reused wastewater would
then be expected to have 5,060 mg/1 total solids and the regular wash
water 1,360 mg/1 total solids. Thus the difference in solids concentration
of the two waters is the same as at the start of the test. The city
water normally contains 180 mg/1 total solids while the system effluent
had 3,550 mg/1 total solids, a difference of 3,370 mg/1. At the
completion of the test, the difference was 3,700 mg/1, indicating that
the same amount of soil was washed out of each load.
The first time the water is used, almost 3,300 mg/1 solids are added
to it. By reusing it, an additional 1,500 mg/1 were added. Wastewater
treatment would be expected to remove 10% of these solids (based on the
averages of Table 73), thus providing 4,500 mg/1 in the treatment efflu-
ent for the next load of washing to be done. The final solids content
after this second load would be expected to be greater than 4,500 mg/1.
This trend would be more pronounced for heavier soil items. Once again,
it is apparent that dissolved solids buildup will limit the reuse of
the wastewater in the laundry.
Personnel at the laundry examined both loads of table linen, and could
find no difference in the cleaned quality of the two articles. No
grease absorption was visible.
172
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TABLE 78
LINEN LAUNDRY WASTEWATER
REUSE TESTING FOR TABLE LINEN
pH - units
Operation
Break
Carryover
High Suds
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Gallons Water
216
655
655
655
655
655
655
655
655
Reuse
12.3
12.05
11.4
11.0
10.75
10.55
10.3
10.05
9.95
City
12.3
12.0
11.55
11.05
10.05
10.2
9.8
9.5
9.1
TOC _ mg/1
Reuse
800
740
590
400
285
^ 205
170
160
140
City
1120
570
205
124
108
92
84
71
52
Total Solids _ mg/1
Resue
17,100
11,300
6240
4600
4240
3920
3690
3700
3670
Cit^
9390
4570
1810
1010
595
537
318
395
317
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LINEN LAUNDRY WASTEWATER TREATMENT SYSTEM PROCESS EVALUATION
AND APPLICABILITY
Based on the results of this test work, it was demonstrated that linen
laundry wastewater can be effectively treated to meet all applicable
sever discharge standards, and reduce BOD and suspended solids to levels
such that no wastewater surcharges would have to be paid. The
application of the treatment system will be mainly in those areas where
government authorities are exerting pressure because of hexane soluble
violations. This is a problem for all linen laundries. There is no
economic benefit to installing a treatment system to reduce sewer
surcharges because of the high cost of linen laundry treatment. There-
fore, unless a linen laundry is forced to treat wastewater by municipal
authorities, there is no point in installing a treatment system.
For light soil linen laundries, only a flotation vacuum filtration system
will be necessary to meet sewer codes, while for heavier soil laundries,
the DE filter is necessary to increase the overall treatment efficiency.
No post treatment after DE filtration would be required. In most
instances, linen plants may be designed from bench scale laboratory
tests rather than expensive pilot plant testing due to the relative
weakness of the wastewater, and lower degree of treatment skill required.
A linen laundry owner washing 10,000 kgs (22,000 Ibs) per day may find
he will have to invest at least $30,000 for a flotation vacuum filtration
system and plan on spending a minimum of $50 per shift operating costs.
Capital costs for the linen.system are lower due to the smaller size
flotation tank and vacuum filter required to handle the wastewater solids.
The costs at the Roscoe plant may be considered the other extreme in
this case. The exact economics of each laundry will vary from plant to
plant.
More information on linen laundry wastewater quality variation is needed
to determine the universality with which the above treatment system
can be applied. With respect to the fact that most investigators in the
past have recommended alum for laundry wastewater treatment, information
is required on the variability expected in required chemical treatment
techniques due to the changes this makes in sludge handling alternatives.
Likewise, the effect of alternate supply systems on wastewater treatment
needs to be more fully identified in relation to the overall wastewater
treatment picture. The above information plus some knowledge of laundry
profits and losses would help provide break even analyses for a variety
of wastewater treatment situations.
174
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SECTION VIII
RECOMMENDED WASTEWATER TREATMENT PRACTICE
FOR THE LAUNDRY INDUSTRY
Based on the foregoing sections of this report, it is possible to general-
ize somewhat as to how the laundry industry as a whole should View and
handle wastewater treatment. Pertinent observations concerning wastewater
reuse can also be made.
As demonstrated by local sewer ordinances, the attitude of the federal
government, and the character of laundry wastewater, it becomes evident
that the decision for wastewater treatment will soon not be one of free
choice. When taking action in this regard, it is imnerative that the
proper procedure in handling the water pollution problem be employed to
prevent needless expenditure of funds and to insure that the desired re-
sult is attained.
When embarking upon a wastewater treatment venture, the laundry owner must
first identify exactly what the problem constituents are, and if possible
where they are coming from. This can be done readily by many analytical
laboratories. He must also be aware of the attitude of the enforcement
officials so that future problem areas not immediately a concern can be
readily ascertained. If the source of a problem can be found, e.g. lead
in printer's towels, the problem can be dealt with by eliminating this
customer, but it merely shifts the burden elsewhere and does not resolve
the ultimate lead problem. More often than not, this will not be possible
due to the large number of clients a commercial laundry may have and to
the heavy analytical expense required to identify the compounds present in
each client's wash. It then becomes a matter of identifying the level and
degree of variability of the contaminants under consideration. As noted
before, hexane solubles are likely to be prohibited and pH limits specified
within certain ranges. In identifying the levels and variation of the con-
taminant, the laundry owner will want to insure that waste samples repre-
sentative of what a treatment system would be expected to handle are ob-
tained. Generally, several one hour to two hour composites to represent
an equalization basin effluent over a day's operation will be adequate.
If, the laundry wash mix varies radically, this procedure will want to be
repeated several days. Each sample should then be analyzed for the prob-
lem constituents.
175
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At this point, a wastewater treatment consultant should be employed to an-
alyze the data generated and obtain additional samples so that a wastewa-
ter treatment technique may be identified that will resolve the problem.
Based on the consistency and effluent quality of the bench tests, recom-
mendations on whether pilot plant studies are required can be made. As
noted previously, for those plants with a heavy metal problem or a corn-
pies? wastewater similar to the Roscoe laundry requiring a sophisticated
treatment technique, pilot plant studies will be required. Though these
may cost several thousands of dollars, it is well worth it to protect a
$50,000 investment. Smaller laundries, of course may not be able to af-
ford pilot plant work.
Based on.the bench test or pilot plant results, a full scale unit can be
designed to resolve the water pollution problems. The laundry owner is
now in a position to determine exactly his economic position, i.e. how
much he may have to increase prices or if he can afford the system at all.
Presuming that the owner can afford the treatment system, he should then
make provision to do as many of the following items as possible:
1. Find a location for the treatment system away from work areas
of high activity to facilitate operation and maintenance of the
unit. The treatment system size should not be cut to save space.
2. Provide space for an equalization tank capable of holding at
least one hour of his plant flow and space for
20,000 liter (5,000 pal.) bulk chemical tanks.
3. Change supply system to be compatible with the treatment tech-
nique employed, if required.
4. Provide an area for locating a sludge hauling container, totally
enclosed and inaccessible to children.
5. Assign a good maintenance engineer to the operation of the unit
so that he may immediately familiarize himself with the treat-
ment system and plan on allocating one half of his time to the
operation and maintenance of the unit. These people will also
generally have some practical suggestions on component selection
and location that will later provide lower maintenance costs.
If possible, he could be sent to a short seminar on waste
treatment. These are often given at local universities or in
large cities.
The laundry owner is now ready to install the treatment system and begin
its operation. If all the preceding steps have been followed and with the
aid of a reputable wastewater consultant, the water pollution control prob-
lem should now be resolved. Likewise, the laundry owner will no longer
have to pay a BOD or suspended solids surcharge.
176
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During the course of the treatment system design, close attention should
be given to the area of sludge handling, as it was pointed out that uti-
lizing such chemicals as alum for coagulation will result in a residual
scum that is virtually nondewaterable except by expensive precoat filtra-
tion. Thus consideration may be given to changing laundry wash formulas
to lower the sludge disposal cost, which as shown previously is consider-
able. The difference between the txro sludge disposal technique (alum
sludge vs. calcium chloride sludge) will determine if it is economical to
change the wash formula. Any future change in the wash formula of course
should be anticipated so that its effect on the treatment system can be
determined.
WASTEWATER REUSE COST ANALYSIS
In the following analysis, three cases for laundry wastewater reuse will
be considered; those laundries with a present washroom cost of 13.2
-------
TABLE 79
REQUIRED WATER QUALITY FOR
HEAT EXCHANGERS
Parameter
Turbidity, mg/1
Total Hardness as CACO.J, mg/1
Silica as Si02, mg/1
Total Solids, mg/1
Maximum
Level Allowable
50
50
50
Wastewater
Effluent
20 - 60
1,000
20 - 200
3500-4000
178
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40%
to Sewer
50%
City Water
50% to Reuse
Hot Water
Storage
Steam Heat
t>
•-i
O
Hot Water
Storage
Suds-First
Rinses
Waste
Treatment
Wash
I
Final Wash Operations
10%
Evaporative
Losses and Sludge
FIGURE 22
LAUNDRY WASTEWATER REUSE PROPORTIONS
-------
consumed is discharged, to the sewer. The average softening costs for both
softening streams combined is about 2.4c/cu m (9C/1000 gal.) including
amortization, if the reuse stream is considered to contain 200 mg/1 alka-
linity and 1000. mg/1 calcium hardness as calcium carbonate (17).
Table 80 suranarizes wastewater reuse costs for the three cases cited at
the beginning of this section. All costs are given as cents per unit vol-
ume of water actually going into the washing machines. Thus the waste
treatment costs are 31.7c/cu m ($1.20/1000 gal.) of wastewater treated;
but only 28.5c/cu m ($1.08/1000 gal.) of water going to the washers, as
10% of the flow is not actually treated. The sludge is included in this
10% to make the calculations easier, and does not actually induce much er-
ror. The sewer discharge costs are reported for 40% of the total flow,
fresh water costs for 50% of the total flow and softening costs for 100%
of the total flow. The total water costs without reuse include waste
treatment costs for 90% of the flow, fresh water costs for 100% of the
flow, and sewer discharge costs for 90% of the flow. It has been assumed
for these analyses that the fresh water and sewer discharge costs are
equal in terms of cost per unit volume of water.
Table 80 demonstrates that approximately a 10% savings is realized for 50%
water reuse for a laundry with present water costs of 13.2c/cu m (SOc/1000
gal.). It may be evident that in this instance it does not pay extensive-
ly to go to the trouble of bothering with the extra problem of a waste-
water reuse system, especially as the cost and maintenance of an extra
water heating and storage system must be considered.
For a laundry whose water costs are 26.4c/cu m ($1.00/1000 gal.)
the net savings from reusing 50% of the treated water is 20% of the
costs associated with no reuse. For this instance, wastewater reuse is
becoming attractive. For a laundry whose water costs are 52.8c/cu m
($2.00/1000 gal.) a 30% savings in water costs is realized.
Figure 8 of Appendix A indicates that these extreme costs (32c/cu m)
($1.20/1000 gal.) occur in only 8% of the laundries. Therefore, it is not
anticipated that cost savings greater than 20% could be realized on a
wide scale. Wastewater reuse will have its most extensive application
where raw water costs are high. However, the economics and situation
of each individual laundry will be different, and this will affect the
wastewater reuse decision.
j
For the Roscoe laundry which pays only about 8c/cu m (30C/1000 gal.) for
raw wastewater and no sewer use tax, reuse can offer little cost savings,
especially in view of the expensive waste treatment cost. Thus, wastewater
reuse application, though technically feasible, will not offer much
respite from high operating costs in low water cost areas such as this.
The foregoing discussion can be taken to apply to all types of laundries.
180
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TABLE 80
LAUNDRY WASTEWATRR REUSE COST ANALYSES
Item Water Costs - C/cu m going to the Washers
13.2c/cu m ~~~26.4c/cu m 52.8c/cu m
(6.6c/cu m for sewer (13.2c/cu m for sewer, (26.4
-------
SECTION IX
REFERENCES
1. Wollner, H. J.f Kumin, V. M. and Kahn, P.A. , Clarification by
Flotation and Re-Use of Laundry Waste Water, Sewage and Industrial
Wastes. ^6:509 (1954).
2. Mason, D. G. and Wullschleger, R. W., Development of a Linen Laundry Waste
Treatment System. Report authored for Linen Supply Association
of America (1969).
3. Fair, G. M., Geyer, J.C. and Okun, D.A., Water and Wastewater
Engineering. Vol. 2. John Wiley and Sons, New York, N.Y. (1968).
4. Anderson, N.E., and Sosewitz, B., Chicago Industrial Waste Surcharge
Ordinance. Journal Water Pollution Control Federation, 43:1591 (1971).
5. Maystre, Y. and Geyer, J. C., Charges for Treating Industrial
Wastewater in Municipal Plants, Journal Water Pollution Control
Federation 42:1277 (1970).
6. Anon., Standard Methods for the Examination of Water and Wastewater,
Thirteenth Edition, American Public Health Assoc., American Water
Works Assoc., and Water Pollution Control Fed. (1970).
7. Babbitt, A. E. and Bauman, E. R., Sewerage and Sewage Treatment,
John Wiley and Sons Inc., New York, New York (1958).
8. Rosenthal, B. L., Industrial Laundry Waste Water Treatment Study,
Project No. 48 of Massachusetts Health Research Institute, Inc. (1963).
9. Coackley, P. and Jones, B.R.S., Vacuum Sludge Filtration I, Interpretation
of Results by the Concept of Specific Resistance, Sewage and Industrial
Wastes, 28:963 (1956).
10. Manual on Disposal of Refinery Wastes, chapter 5, Copyright American
Petroleum Institute (1969).
11. Dahlstrom, D.A. and Cornell, C.F., Modern Operating Methods and Costs
on Sewage and Waste Sludge Filtration, Presented at the 1971 Annual
Meeting American Chemical Society, Washington, D.C.
12. Flynn, J. M. and Andres, B., Launderette Wash Treatment Processes.
Journal Water Pollution Control Federation. J35:783 (1963).
13. HcKee,J.E., and Wolf, H.W., eds., Water Quality Criteria, The State
Water Quality Control Board of The Resources Agency of California (1963).
14. Eckenfelder, W. W., Jr., and O'Connor, D. J., Biological Waste Treatment
Pergaraon Press, New York, N.Y., p. 280 (1961).
182
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15. Young, E. F., Water Treatment Plant Sludge Disposal Practices in the
United Kingdom, Journal American Water Works Assoc, 60 ;717 (1968).
16. American Water Works Association Research Foundation, Disposal of
Wastes from Water Treatment Plants, Federal Water Pollution Control
Administration Project No. WP 1535-01-69. New York, N.Y. (1969).
17. Wood. F. 0., Selecting a Softening Process, Journal American Water
Works Association 64:820 (1972).
18. Environmental Protection Agency Water Quality Office, Methods for
Chemical Analysis of Water and WasteT Analytical Quality Control
Laboratory, Cincinnati, Ohio (1971).
19. Anon., Analytical Methods for Atomic Absorption Spectropjhotometry,
Perkin-Elmer Corp. (1971).
20. Ducar, G. J. and Levin, P., Mathematical Model of Sewage Sludge
Fluidized Bed Incinerator Capacities and Costs, Federal Water Pollution
Control Administration, Report No. TWRC-10, Cincinnati, Ohio (1969).
183
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SECTION X
GLOSSARY
1. Afterfloc - Solids formed by the precipitation or crystallization
of dissolved material in water upon standing. This material is
measured as suspended solids in subsequent analyses.
2. Bench Scale Testing - Laboratory testing that closely simulates
full scale waste treatment unit processes and are utilized to
size full scale equipment. The tests are quick, portable,
and easily performed, e.g. flotation, and vacuum filtration.
3. Break - The first step in a wash cycle in which supplies are
used. It is designed to wet down the load and remove as much
of the readily soluble soil as possible.
4. Compressibility - Measured by the slope of a specific resistance -
pressure logarithmic plot, and indicative of the "collapsibility"
of the vacuum filter cake. A compressible sludge does not have
a strong pore structure, and collapses under high vacuums.
5. Cycle Time - The time required for a vacuum filter to make one
complete drum revolution.
6. DE Body Feed - The addition of filter aid (DE) while filtering
wastewater on a precoated DE filter to the wastewater feed;
thus providing a continuous clean surface for subsequent solids
separation.
7. DE Filter Backwash - The act of reversing the water flow to the DE
filter at a flowrate sufficient to knock off the filter cake.
This occurs when the filter cake resistance is too great to
accommodate the required flow rate.
8. DE Precoat - The initial layer of DE added to the DE filtering
elements prior to starting the dirty wastewater feed. Generally,
0.5 to 0.76 kg/sq m (0.1 to 0.15 Ib/sq f-t) of filter aid is
applied to treat the initial wastewater flow.
9. Dissolved Solids - Those solids passing a 0.45 u membrane filter
or a glass fiber mat as defined in reference 6 under suspended
solids.
10. Dry Time - That portion of the vacuum filtration cycle occurring
between the point of drum rotation out of the sludge to the point
of vacuum release.
11. Filter Septums - The filter aid support element, generally long
tubular stainless steel supports or cloth bag supports, that
retain the filter aid.
12. Filter Leaf - A small filter septum of known area that is free
draining and utilized for holding filter cloths during vacuum
filter sizing bench tests.
184
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13. Flush - A wash operation occurring at the beginning of the wash
cycle in which no supplies are added to merely wash out
loose soil and dirt to increase the effectiveness of the supplies
when they are added.
14. Grease - See Hexane Solubles.
15. Heavy ^fetals - Lead, Cadmium, Zinc, Mercury, Iron, Chromium,
Nickel, and Copper in this report.
16. Hexane Solubles - Any material, e.g., fats, oils, waxes, and
other non-volatiles, extracted from an acidified sample of waste
by normal hexane.
17. Industrial Laundry - A laundry washing primarily shop towels,
printer's towels, and dust mops, wherein the wastewater contami-
nation is abnormally high compared to other laundry types.
18. Linen Laundry - A laundry washing primarily linen flatwork such
as sheets, table linen, continuous towels, kitchen towels, etc.,
wherein the wastewater contamination is low compared to other
laundry types.
19. Mass Loading - The mass of suspended solids applied to a unit
area of the flotation tank in a unit of time, measured as
kgs/day/sq m or Ibs/day/sq ft.
20. Pickup Time - That portion of the vacuum filtration cycle occurring
during the time the drum is submerged in the sludge.
21. Pilot Plant Testing - Small scale continuous testing of model
waste treatment processes to develop design data for direct
scale up to full scale equipment.
22. Recycle Ratio - Pressurized flowrate divided by the raw flow rate
x 100, expressed as a percentage.
23. Refractory - non-biodegradable.
24. Rise Rate - The rate at which solids separation occurs in a
flotation unit, i.e., the velocity with which a suspended particle
is lifted in the liquid medium.
25. Scum - The. liquid fraction containing the solids that is skimmed
from the flotation unit and used as vacuum filter feed.
26. Sewer Charge - A sewer use tax, or cost charged by a municipality
to a sewer user to pay for this service.
-27. Sewer Surcharge - A sewer tax above the sewer charge determined
by the strength of the wastewater discharge, generally in terms
of wastewater BOD and suspended solids.
185
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28. Soil - The dirt, grease, and other material present in laundry
prior to washing. This is the material that must be cleaned
from the articles.
29. Sour - An acid compound added to the last wash operation to
adjust the pH of the final rinse to near neutrality.
30. Specific Resistance - A measure of the ability of a vacuum
filter sludge cake to impede the flow of water through its pore
structure; utilized to measure the effect of sludge chemical
conditioning.
31. Submergence - A measure of sludge depth in the vacuum filter,
usually expressed as the percentage of the drum diameter
beneath the filter vat sludge level.
32. Suds - The wash operation wherein the detergent is added to
emulsify- oil and greases and to suspend the majority of the
soil for discharge.
33. Supplies - The chemicals used for removing the soil in the wash
cycle; this includes all chemicals added in the wash cycle.
34. Surface Overflow Rate - The hydraulic loading of the flotation
unit per unit area of tank per unit time, usually expressed as
1pm/sq ra(gptn/sq ft) of tank.
35. Uniform Laundry - A laundry primarily washing shirts, pants,
coveralls, and uniforms of various colors and types.
36. Vacuum Filter Blinding - The deposition of solids in the weave of
a filter cloth such that the cloth cannot pick up any new solids.
On a belt filter, cloth blinding leads to no cake discharge from
the discharge roll; therefore, no sludge is being dewatered by
those areas manifesting blinding.
37. Vacuum Filter Solids Loading - The mass of dry sludge solids
picked up per unit area of filter; a measure of cake thickness.
38. Vacuum Filter Yield - The mass of dry sludge solids dewatered on
a unit area of filter in a unit of time, normally measured as
kgs/sq m filter/hr (Ibs/sq ft/hr).
39. Vacuum Filtrate - The water passing through the filter cloth and
not retained in the sludge.
40. Wash Cycle - The entire operation required to launder a machine
load of an article.
41. Wash Formula - The complete schedule of application of detergents
and other supplies in laundering.
186
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42. Wash Operation - One discrete machine discharge during a wash
cycle, e.g. a flush, suds or rinse.
43. Washroom - The area where the wash wheels are located.
44. Wash Wheel - The washing machine itself.
45. Water Level - The depth of water in the cylinder of the wash wheel
while it is laundering an item. This depth is often used to
calculate the volume of water used in the laundering process, and
in the calculation of water volume used in one wash operation.
46. Wipers - Shop towels and printer's towels.
187
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SECTION XI
ABBREVIATIONS
BOD - Biochemical Oxygen Demand
BTU - British Thermal Units
cm - centimeter
cfm - cubic feet per minute
cmm - cubic meter per minute
cu ft - cubic feet
cu m - cubic meter
cu yd - cubic yard
DE - diatomaceous earth
ft - foot
gal. - gallons
gpm - gallons per minute
hp - horsepower
hr - hour
in. - inches
kg - kilogram
kg-cal - kilogram-calories
1 - liter
188
-------
lj> - pound
1pm - liters per minute
ji - microns
yg - micrograms
umhos - micro-ohms
mj^ - milligram
min - minute
mm - millimeter
mpjn - meters per minute
psi - pounds per square inch
sq cm - square centimeter
sq^ ft - square feet
sq m - squa're meters
TOG - total organic carbon
189
-------
SECTION XII
APPENDICES
190
-------
APPENDIX A
LINEN AND INDUSTRIAL LAUNDRY INDUSTRY SURVEY
191
-------
LINEN AND INDUSTRIAL LAUNDRY INDUSTRY SURVEY
CONCLUSIONS
1. There is a definite relationship between laundry wash loads and water
consumption.
2. Industrial laundries use more water and pay a higher sewer surcharge
than linen laundries.
3. Laundry location is much more important in determining water costs than
laundry size.
4. Based on the sewer ordinances examined, it would appear that most
laundries will have problems meeting the pH and grease standards without
treatment. Industrial laundries may have heavy metal problems
dependent on what they wash.
5. Industrial laundries have higher washroom water costs per product unit
than linen laundries.
6. There is a great deal of variation in water costs, sewer costs and
surcharges, washroom costs, and volume of water used per unit weight of
laundry for all laundries, due to laundry location, differences in items
washed, differences in wash formulas and procedures, etc.
7. Washroom costs for laundries are now about 13c/cu m (50C/1000 gallons)
for surcharges, sewer use taxes, and raw water (1971 dollars).
RECOMMENDATIONS
1. Expand on the present survey to obtain more data on wastewater quality
variation between laundries and to more specifically delineate water
usage rates and costs for the various laundry types.
2. Apply the information obtained from a more detailed survey to specific
wastewater treatment conditions and laundry situations so that break even
analyses on laundry waste treatment costs can be performed. This will
help define the magnitude and scope of the water pollution problem more
clearly for the laundry industry.
192
-------
LAUNDRY INDUSTRY SURVEY
As part of the laundry wastewater treatment demonstration system project, a
laundry industry survey was conducted for the purpose of obtaining in-
formation on what laundries were paying for water as well as information
on water pollution control problems in general for the laundry industry.
In this regard, questionnaires were prepared and sent to member laundries
of the project supporting organizations requesting information on types of
articles laundered, supplies, wash weight per week, w»ter cost and
usage. Table A-l is a duplicate of the questionnaire utilized. The forms
were filled out by the member laundries and returned to Envirex for correla-
tion and analysis. A copy of a water bill was requested from each laundry
so that the majority of the figures obtained could be substantiated. This
report summarizes the responses to those forms.
Approximately 160 forms were received of which 116 were utilized. .The
remaining 44 forms were not utilized either because the forms were
incomplete, did not include water consumption data, or for other reasons.
Of the forms used for this survey, 96 were from linen or industrial plants
and 20 from diaper plants. All information from the diaper plants is
reported in Appendix F. For the purpose of this survey, all plants
laundering more than 75% industrial garments, wipers, and mops were
considered to be industrial plants; and all plants laundering more than 75%
linen flatwork and garments were considered to be linen plants. Using
these classifications, 45 of the reporting laundries were industrial, 43
were linen, and eight were combinations of both. Included with the above
survey forms were 23 different sewer ordinances and 18 laundry wastewater
analyses. All data reported is for the year 1971.
The data obtained was averaged and correlated to obtain information on both
the average and range of laundry water consumption and costs. The average
water costs and usage for all laundries are presented in Table A-2. From
this table, it can be seen that water costs and laundry sizes cover a wide
range of values. The wide range of values shown for all parameters should
serve as a warning against applying the reported average values indiscrim-
inately. This, coupled with the facts that all water consumption data
probably includes sanitary sewage, that there is an indeterminate
geographic effect upon the data, and that all water volume data will include
results of faulty water meters demonstrates that the data presented should
be utilized to only indicate trends and general magnitudes rather than
exact or specific relations.
Sewer cost data is not as abundant as water cost data as many launderers
included water bills that indicated no sewer charge. However, many
municipalities bill this separately, i.e., they do not include it on a
water bill. Thus, it is not known how many laundries may have reported no
sewer charge since it was not on the water bill, and still have paid a
sewer charge. Other laundries indicated there was a sewer charge, but
enclosed no bill for it. As much data as possible has been included in
Table A-2.
193
-------
TABLE A-l
IIL - LSAA SURVEY FORM FOR
LAUNDRY WASTEWATER TREATMENT PROJECT
1, Our plant operates:
• hours per day
hours per day
hours per day
Monday through Friday
Saturday
Sunday
lhs) can be broken
2. Our average WEEKLY wash poundage (_
down as follows:
A. Linen Supply Flatwork
Ibs light soil (bed linen, bath towels, etc.)
Ibs medium soil (table linen, kitchen towels, etc.)
Ibs heavy soil (aprons, bar towels, etc.)
Ibs colored linens
B. Linen Supply Garments
Ibs whites (cotton)
Ibs whites (synthetics)
C. Dust Control
Ibs mops
Ibs
Ibs colors (cotton
Ibs colors (synthetics)
D. Industrial Flat
Ibs shop towels
Ibs
Ibs entrance mats
Ibs
Ibs printer towles
E. Industrial Garments
Ibs whites (cotton)
Ibs whites (synthetics)
194
Ibs colors (cotton)
Ibs colors (synthetics)
-------
TABLE A-l, CONTINUED
3. In addition to the common wash supplies such as alkali, soap, bleach,
and industrial detergents, do you use:
Sour Type
Mildew Inhibitor Type
Flame Retardant Type
Non-Ionic Detergent Phosphates
CMC Softeners
Solvents Dust Treating Compounds
4. Has an analysis been made of your wastewater effluent;
If yes:
City Private Agency
Please enclose a copy of their report.
5. Please enclose copies of the following:
A. Recent monthly water bill. Does bill include:
1. Cost of fresh water? Yes No
2. Sewer use charges? Yes No
3. Sewer surcharges? Yes No
If not, please include this information:
What was the total water consumption in gallons for the period
covered by the enclosed water bill? gallons.
B. Local sewer use ordinance. This will be of vital help in
determining typical sewage requirements througout the USA.
Thank you. Please use the reverse side for any additional comments you
wish to make.
195
-------
TABLE A-2
AVERAGE WATER COSTS AND USAGE
FOR 96 LINEN AND INDUSTRIAL LAUNDRIES
Raw Water Cost
(c/cu m)
Sewer Charge
(C/cu m)
Sewer Surcharge
(C/cu m)
Water Consumption
(1000 Ipd)
Laundry Size
(1000 kg/week)
Liters Water Consumed/
kg laundered
Total Washroom Costs
(C/cu m)
Washroom Water Costs
(c/100 Igs laundered)
Range
3.2-18.5
0.5-29.6
0.1-15.9
68-1136
54-267
21.6-65.0
3.8-37.0
18-134
Average
7.4
5.8
4.4
378
50
38.3
14.8
73
No. of
Values >0
91
64
22
68
95
67
64
44
196
-------
It can be seen that laundries were paying an average of 14.7c/cu ra
(56C/1000 gal.) for raw water, sewer charges, and sewer surcharges. This
is reported as total washroom costs in Table A-2. This does not include
the cost of softening. The average laundry water consumption was seen to
be 260 cu m/d (100,000 gpd) for laundering 50,000 kg (109,000 Ibs) per
week. Twenty-three percent of the laundries reporting were paying a sewer
surcharge for BOD and suspended solids. None of the laundries indicated
they had waste treatment other than screens or grease trans. Washroom
water costs averaged 59C/100 kgs ($.27/100 Ibs) of items laundered. Com-
paring this to the 11UC to 220c cost per 100 kgs (50c to 100c/lh) laundered
for waste treatment will increase.water related costs significantly for all
laundries, as the maximum washroom water cost vas only 134^/100 kgs (61C/100
Ibs) laundered.
A very good relation was found to exist between laundry size and water
consumption, as demonstrated in Figures A-l and A-2. As laundry wash
load increases in size, water consumption also increases linearly. This
points up the fact that water consumed per pound of article laundered did
not decrease for larger laundries, but that the amount of water required
to launder a unit weight of material is evidently independent of plant
size. However, the volume of water required,per pound of article laundered
does depend on the type of article laundered.
The two lines drawn in Figures A-l and A-2 are least squares regression
lines with correlation coefficients of 0.91 and 0.97 respectively.
Therefore, 90'% to 95% of the plant flow occurring in a laundry can be
accounted for by the quantity of articles laundered. Thus by knowing the
wash load of a laundry, the amount of water consumed can be reliably
predicted for these laundries. By then applying a reduction of 15-20%
of this number to allow for evaporation, sanitary usage, and sludge, a
fairly reliable wastewater design flow can be determined. The variation
In daily wash poundage will determine the daily variation of flow. Thus,
wash poundage is a useful wastewater design parameter.
An attempt was also made to correlate water costs with laundry water
consumption and volume of water used per kilogram of articles laundered with
laundry size. However, there were no correlations of this tyne present.
Laundry location evidently dictates water cost much more so than laundry
size. However, for a particular municipality, there would be expected to
be a good correlation between unit water cost and consumption since most
municipalities charge high volume customers a lower unit rate. The unit
water cost for a laundry will be higher in those areas where water is
scarce.
In general, laundries in the northeast paid the highest water costs and
laundries in the midwest and south had the lower water costs. Likewise,
there was no correlation between laundry size and volume of water
consumed per unit mass of laundered articles. Apparently, large laundries
do not use water any more efficiently than small ones, and there is a
fixed volume of water required to get a unit weight of article cleaned.
197
-------
•u
a
c
o
o
o
e.
en
o
u
a)
1136
757
378
265
189
113
37.8
9.1
18.2 27.3 36.4 45.5 91.0
I»aundry Wash Load - 1000 kp/week
182
FIGURE A-l
WATER CONSUMPTION VS. INDUSTRIAL LAUNDRY SIZE
-------
1136
o
D
B
Q
2 189
^o
vo S
113
37.8
9.1
7
-I
18.2 27.3 36.4 45.5 91.0
Laundry Wash Load - 1000 kg/week
FIGURE A-2
WATER CONSUMPTION VS. LINEN LAUNDRY SIZE
182
-------
Table A-3 presents a. survey comparison of linen and industrial laundries.
From Table A-3 it can be noted that for the laundries surveyed, it
appears that industrial laundries consume about 10% more water than
linen laundries per unit mass of article laundered. This figure seems low
in view of the fact that many industrially laundered items will generally
have 4-6 more rinses than linen laundered items. However, this data is
an indication that industrial laundries in general do use more water per
unit weight of laundered items. This cannot be taken as an exact
figure due to the limitations of the survey previously cited. Likewise
the slopes of the two lines of Figures A-l and A-2 demonstrate about £he
same difference; as the slope of the.linen laundry curve is 39.1 I/kg
laundered (4.7 gal./lb) and the industrial curve 42.5 I/kg (5.1 gal./lb).
It may also be noted from Table A-3 that average sewer and water costs are
almost equal for industrial and linen laundries, which is to be expected.
Industrial laundries pay a sewer surcharge approximately 2 1/2 times
higher than linen laundries due to the higher concentrations of BOD and
suspended solids in their wastewater, as shown in Table A-3. This same
table indicates that the linen laundries responding to the survey were
somewhat larger than the industrial laundries. It is not known if this
is generally true or merely characteristic of those laundries responding
to the survey. Total washroom water costs are about equal for linen arid
industrial laundries in cents/cubic meter. However, when expressed in
terms of cents per 100 kgs of articles laundered, it can be seen that
industrial laundering washroom water costs are about 20% greater than
linen laundry washroom costs. This is due to the facts that industrial
laundries do use more water and pay higher sewer surcharges. Figures A-3
and A-4 depict this information in a frequency distribution histogram.
These figures demonstrate that about 50% of the industrial laundries have
washroom costs greater than 66C/100 kgs (30C/100 Ibs) laundered while only
17£ of the linen laundries exceed this figure. Logically, this is a good
check on the survey results since this type of information would normally
be anticipated.
Figures A-5, A-6 and A-7 depict similar histograms for raw water costs,
sewer charges, and sewer surcharges. These histograms are not
separated into linen and industrial laundries, as there was no significant
difference in the data between the two laundry categories for raw water
and sewer charge costs. The surcharge data was not separated, because
there were not enough data points to provide a realiable histogram.
The variation obtained in this cost data is self-evident, with the most
frequently occurring costs being the following:
water cost - 6.6 to 7.9c/cu m (25c to 30C/1000 gal.)
sewer charge - 2.6c to 5.3c/cu ra (10$ to 200/1000 gal.)
surcharge - 0 to 1.3c/cu m (0 to 5C/1000 gal.)
Thus, it can be seen that water is relatively cheap for the majority of
laundries, and that waste treatment for the sake of reducing, surcharges
would have to be exceedingly economical. As evidenced in the main report,
this was not the case. The wide range of values reported by the laundries
200
-------
TABLE- A-3
COMPARISON OF WATER COSTS AND USAGE
FOR LINEN AND INDUSTRIAL LAUNDRIES
Range
Average
No. of Responses
NJ
o
Item
Raw Water Cost
(C/ cu m)
Sewer Charge
(
-------
30 -
Q>
y
§ 20
I
10 -
0 22 44 66 88 110 132
Linen Washroom Costs - C/100 kgs laundered
FIGURE A-3
LINEN LAUNDRY WASHROOM COSTS INCLUDING SEWER USE TAXES,
FRESH WATER COSTS, AND SEWER SURCHARGES
AS A FUNCTION OF PRODUCT UNIT WEIGHT
202
-------
30
I
CJ
8
20
Q)
I
10
0 22 44 66 88 110 132
Industrial Washroom Costs - C/100 kgs Laundered
FIGURE A-4
INDUSTRIAL LAUNDRY WASHROOM COSTS INCLUDING SEWER USE
TAXES, FRESH WATER COSTS, AND SEWER SURCHARGES
AS A FUNCTION OF PRODUCT UNIT WEIGHT
203
-------
30 r-
25
20
Q)
u
3
U
8
15
o
c
u
C7-
0)
10
0
2.6 5.3 7.9 10.6 13.2
Clean Water Cost - C/cu
FIGURE A-5
FRESH WATER COSTS FOR LAUNDRIES
15.9
13.5
204
-------
30 H
I
0)
u
8
3
0)
g.
0)
20 -
10 -
0
2.6 5.3 7.9 10.6
Sewer Use Charges
FIGURE A-6
SEWER USE CHARGES FOR 100 LAUNDRIES
.13.2 15.9
C/cu m
IS. 5
205
-------
30 -
I
3
u
o
20-
10-
0 2.6 5.3 7.9 10.6 13.2
Sewer Surcharge - c/cu m
FIGURE .._A- 7
SEWER SURCHARGES FOR BOD AND SUSPENDED SOLIDS FOR LAUNDRIES
206
15.9
-------
also amply demonstrates that each individual laundry will have to
consider the economics of wastewater treatment from its own unique
position. Figure A-8 presents the total washroom costs in histogram
fashion, and demonstrates that the majority of laundries pay 8c to 13c/
cu m (30c to SOc/1000 gal.) for water and sewer. Those costs go as low
as 2.6c/cu m (IOC/1000 gal.) and as high as 37.0c/cu m ($1.40/1000 gal.)-
Waste treatment is of course more economical for those laundries with high
costs when wastewater reuse is considered.
Table A-4 presents the ranges of contaminant concentrations allowed in
sewer discharges for 20 different municipal sewer ordinances included in
the industrial survey. The table shows a wide range of concentrations
allowable for almost all substances. Of particular interest to all
laundries are the pH and grease limitations. In general, almost all
laundries will exceed these standards; and many industrial laundries will
have problems with some of the heavy metals. It may also be noted in
regard to sewer ordinances that many of the smaller municipalities will have
an ordinance that states merely "no toxic substances or substances that
may interfere with the treatment processes shall be discharged to the sewer
in concentrations considered by the city engineer to be excessive." Thus,
they do not put a number or limitation on anything that is discharged,
but leave it to their own discretion. In these instances, the same problems
that occur with the ordinances that set specific limits also occur,
perhaps more so. Temperature and the other items were not large problems.
It may be noted that standards for such ordinances are not going to become
more lax but more stringent. In some instances, municipalities are no
Ipnger applying a surcharge to wastewater BOD and suspended solids but
are merely requiring any sewer user with BOD or suspended solids above
a specified level to treat their wastewater to reduce these parameters to
the required concentration. Therefore laundries can expect wastewater
treatment to become a very large part of their future. Newly constructed
laundries should have the wastewater treatment system designed in with the
plant just as the washers, driers, and ironers are; since in the long run,
almost all laundries are going to be faced with unfavorable municipal
attitudes towards their discharges. Since laundries come in all sizes and
types, the variety of treatment methods will be considerable.
All the data obtained from the industrial survey is reported in Table A-5.
207
-------
25
20
Vc
U
o
u
c
g. 10
0)
14
5.3 10.6 15.9 21.1 26.4 31.7
Washroom Costs - C/cu m
37.0
FIGURE A-8
LAUNDRY WASHROOM WATER COSTS INCLUDING FRESH WATER,
SEWER SURCHARGES, AND SEWER USE CHARGES FOR 100 LAUNDRIES
208
-------
TABLE A-4
RANGES OF SEWER DISCHARGE STANDARDS FOR
APPROXIMATELY 20 MUNICIPAL
SEWER ORDINANCES
Item
pH - units
Temperature - F
Grease - rag/I
Phenol - mg/1
Cyanide - mg/1
Zinc - mg/1
Cadmium - mg/1
Iron - mg/1
Hexavalent Chromium - mg/1
Copper - mg/1
Mercury - mg/1
Nickel - mg/1
Lead - mg/1
Silver - mg/1
Phosphate - mg/1
Barium - mg/1
Arsenic - mg/1
* Uncommon
Range Allowed
4.5 - 10.5
<100 - 160
<50 - 120
<0.02 - 10
0-2
<2 - 15
<0.02 - 5
<10 - 50
<5 - 10
<1 - 5
<0.0005 - 1.5
<0.1 - 10
<0.1 - 5
<0.1 - 5
<40*
<0.05 - 5*
<0.05 - 5
209
-------
TABLE A-5
INDUSTRIAL AND LINEN LAUNDRY RESPONSES TO THE LAUNDRY INDUSTRY SURVEY
Percentage Mix
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
%
Linen
2
35
65
98
75
— —
90
__
99
90
100
85
65
90
85
10
10
100
20
—
93
5
—
4
%
Indus.
100
98
65
35
2
25
100
10
100
1
10
—
15
35
0
15
90
90
— _
80
100
7
95
100
96
Raw Water
Cost -
C/cu m
8.1
7i4
3.7
10.6
4.8
5.5
8.2
8.7
5.5
4.2
4.0
7.4
6.1
7.1
5.8
10.6
5.7
5.8
8.7
4.5
14.5
11.4
9.8
6.4
5.3
Sewer
Charge
C/cu m
3.4
11.6
11.1
10.3
__
—
3.4
— —
4.2
4.2
1.3
8.7
2.1
—
2.6
7.1
0
0
4.2
8.3
6.6
21.9
7.1
0
—
Sewer
Surcharge
C/cu m
0
0
0
0
—
—
2.6
—
0
0
0
0
0
0
0
0
0
0
0
0
12.4
0
4.6
—
—
Water
Consumption
1000 Ipd
129
136
568
889
1136
246
1022
269
__
166
386
— —
— .
549
114
—
220
549
95
—
—
261
1060
—
484
Wash
Load
1000
kg/wk
18.2
16.3
74.8
92.2
154.5
36.4
100.3
42.0
26.5
19.9
57.3
90.9
41.0
38.9
22.5
27.3
33.3
68.2
113.6
62.4
102.3
34.1
78.0
40.9
68.2
Liters
Consumed /
Kilogram
laund ered
35.4
41.7
38.3
48.3
36.7
33.3
52.5
32.5
—
41.7
34.2
--
—
71.7
25.0
—
32.5
40.0
41.7
—
—
38.3
42.9
—
35.4
Total
Washroom
Cost
C/cu m
11.4
19.0
14.8
20.9
—
—
14.3
—
9.8
8.5
5.2
16.2
8.2
— •
8.5
17.7
—
—
12.9
12.8
33.5
33.3
21.5
—
—
Location
Cal.
Wash .
Wash.
111.
N.Y.
Mich.
Ind.
Hawaii
Wash. D.C
Ohio
—
Florida
Kan.
Cal.
Wash.
Minn.
Wis.
Wis.
Minn.
Ore.
Penn.
Penn.
Ohio
Can.
Mich.
-------
TABLE A-5, CONTINUED
INDUSTRIAL AND LINEN LAUNDRY RESPONSES TO THE LAUNDRY INDUSTRY STTRVEY
Percentage Mix
No.
26
27
28
29
30
31
32
33
34
35
36
•J \J
37
38
39
40
41
42
43
44
45
46
47
48
49
%
Linen
5
94
100
100
35
3
6
12
96
90
90
100
%
Indus .
100
10
95
6
_^T
100
65
100
97
100
100
100
100
94
100
88
100
100
4
10
100
10
Raw Water
Cost
C/cu m
7.1
18.5
8.7
3.2
11.6
9.0
7.3
7.3
14.5
8.2
4.8
9.0
8.1
4.0
3.2
7.7
6.9:
3.4
6.7
«•»••
12.2
6.6
7.4
Sewer
Charge
C/cu m
0
4.6
1.9
5.2
0
3.5
0
0
7.0
—
_M
2.1
3.5
3.3
4.2
1.5
4.5
5.2
0.5
6.3
«_.
0
7.9
7.1
Sewer
Surcharge
C/cu m
0
4.8
0.9
0
0.5
0
—
—
12.4
—
—
0
0
0
0
0
0
0
0
0.5
2.5
0
6.3
0
Water
Consumption
1000 Ipd
95
132
—
—
424
322
201
409
—
— "
—
— —
136
129
488
—
—
409
405
148
356
435'
Wash
Load
1000
kR/wk
8.5
13.6
21.5
28.5
63.6
50.2
36.0
50.0
57.3
30.0
39.1
45.5
15.2
18.2
55.9
22.0
29.4
64.9
18.2
40.9
.25.9
40.9
50.0
63.6
Liters
Consumed /
Kilogram
Laundered
55.8
48.3
—
__
33.3
32.5
27.5
40.8
—
—
—
—
45.0
35.4
43.7
—
—
31.7
49.1
27.5
35.8
34.2
Total
Washroom
f* *.
Cost
C/cu m
7.1
27.9
11.5
8.4
12.2
12. '5
—
—
33.9
—
—
6.9
12.5
11.4
8.2
4.6
12.2
12.0
4.0
13.6
— —
12.2
20.9
14.5
Location
N.J.
N.Y.
Tex.
— —
Penn.
Mass.
"ill.
111.
Penn.
Penn.
Ind.
Missouri
Mass.
Mich.
Ohio
Texas
L
Ohio
Montana
Missouri
111.
Penn.
Colorado
Minn.
-------
s>
TABLE A-5, CONTINUED
INDUSTRIAL AND LINEN LAUNDRY RESPONSES TO THE LAUNDRY INDUSTRY SURVEY
No.
50
51
52
53
54
55
56
57
58
59
69
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
Percenta
Linen
80
100
100
75
90
97
90
98
95
100
96
97
90
7
75
95
90
90
85
85
100
6
2
—
ge Mix^
Indus.
20
«M
— — •
25
10
3
10
2
5
•r_
4
3
10
93
25
5
10
10
15
15
94
100
98
100
100
Raw Water
Cost -
C/cu m
8.5
7.1
7.1
4.5
10.8
8.2
7.7
_«.
— —
3.7
7.1
8.2
6.6
6.8
6.8
7.8
6.6
10.6
18.2
9.5
7.1
6.8
11.9
5.8
5.5
Sewer
Charge
_C/cu__jn
2.6
__
8.2
1.1
2.0
__
12.7
—
5.0
—
--
8,2
__
__
1.3
1.6
__
6.9
14.5
1.6
—
6.8
2.4
6.9
—
—
Sewer
Surcharge
C/cu m
0
—
0
0.1
0
__
5.5
__
1.7
—
0
0
—
__
0
0
__
0
4.2
1.3
2.2
_—
1.6
5.8
—
—
Water
Consumption
1000 Ipd
68
322
969
291
295
420
685
852
—
855
568
132
--
—
220
515
348
330
197
443
643
140
556
522
—
Wash
Load
1000
kft/wk
12.6
40.9
113.6
30.0
36.4
66.5
93.2
261.9
18.2
102.3
90.9
14.9
21.5
55.9
30.2
68.2
27.3
74.1
42.0
69.5
—
14.5
18.7
77.3
66.0
45.5
Liters
Consumed/
Kilogram
Laundered
27.5
39.2
42.5
49.1
40.8
31.7
36.7
21.7
—
41.7
31.2
44.6
—
—
36.2
37.5
65.0
35.0
22.5
31.7
—
48.3
—
35.8
38.7
—
Total
Washroom
Cost
C/cu m
11.1
—
15.3
5.7
12.8
— —
25.9
—
—
— —
— —
16.4
—
— —
7.7
9.4
—
7.4
37.0
12.4
—
— —
15.9
18.5
—
— —
Location
Wyo.
•-* .
Fla.
N.Y.
Can.
— ••
Ca.
~—
Mass.
— —
Wis.
Ind.
Ariz.
Ariz.
Neb.
Cal.
Cal.
Minn.
111.
Tex.
Tex.
— —
Tex.
Ind.
— —
Okla.
-------
TABLE A-5, CONTINUED
INDUSTRIAL AND LINEN LAUNDRY RESPONSES TO THE LAUNDRY INDUSTRY SURVEY
Percentage Mix
No.
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
%
Linen
100
—
15
45
45
—
35
1
10
15
10
75
— —
88
—
__
_ _
15
60
70
%
Indus.
100
—
100
85
55
55
100
65
99
90
85
90
25
100
12
100
100
100
85
40
30
Raw Water
Cost
C/cu m
5.8
7.3
6.6
6.1
4.9
4.0
6.6
7.9
6.1
5.8
13.2
9.0
12.4
7.9
7.9
7.4
4.0
5.2
6.1
4.0
10.0
Sewer
Charge
C/cu m
3.7
3.3
4.0
8.2
2.1
—
2.1
6.1
10.8
4.8
—
6.1
29.6
—
1.8
1.8
4.1
—
4.5
7.4
Sewer
Surcharge
C/cu m
0
0
0
8.7
0
—
0
15.9
0
0
—
0
0.8
—
— —
0
0
—
0
0.5
Wat er
Consumption
1000 Ipd
47
180
—
541
—
—
454
242
125
378
79
—
117
284
__
545
333
276
102
492
Wash
Load
1000
kg/wk
11.8
24.6
19.8
11.8
45.5
18.2
182.2
48.7
49.5
21.8
46.5
10.7
24.5
18.2
45.5
84.3
60.5
45.5
47.9
9.5
58.2
Liters
Consumed/
Kilogram
Laundered
23.3
45.0
—
60.0
—
—
45.0
24.2
28,3
40.0
37.5
—
32.5
31.7
—
45.0
36.7
29.2
53.3
42.5
Total
Washroom
Cost
C/cu m
„
11.0
9.9
10.0
21.8
6.1
—
10.0
28.0
16.6
18.0
—
18.5
38.3
—
—
5.8
9.2
—
8.5
18.0
Location
Ariz.
Kent.
Kent.
Kent.
Vir.
Colo .
Can.
Tenn.
Mich.
Ore.
N.Y.
N.Y.
Ark.
Penn.
—
N.Y.
Penn.
N.Y.
Mass.
Fla.
Md.
-------
APPENDIX B
ANALYTICAL PROCEDURES AND BENCH TEST METHODS
214
-------
ANALYTICAL INSTRUMENTS AND APPARATUS
pH meter: Beckman Model 552
Beckman Instruments Incorporated
Fullerton, California
BOD Incubator: Labline No. 3554B Incubator
Lab-Line Instruments, Inc.
Melrose Park, Illinois
Analytical Balance:
Spectrophotometer:
Atomic Absorption
Spectrophotometer:
TOC Analyzer
Turbidiraeter
Type H10
Mettler Instruments Corporation
Right storm, New Jersey
Coleman Model 14
Coleman Instrument Company
Maywood, Illinois
Perkin Elmer Model 403
Perkin Elmer Corp.
Norwalk, Connecticut
Beckman 915 TOC Analyzer
Beckman Instruments Co.
Fullerton, California
Hach Model 2100A Turbidimeter
Hach Chemical Co.
Ames , Iowa
215
-------
ANALYTICAL PROCEDURES AND ANALYSES
The following analyses were performed according to Standard Methods _fojr
the Examination of Water and Wastewater, (6) (Standard Methods) and Methods
for the Chemical Analysis of Water and Waste (18) (WQO).
Total Solids - Method A, p. 535, Standard Methods; The amount of
sample used was determined by weight rather than by volume;
approximately 20 grams of sample was used for total solids.
Suspended Solids - Method C, p. 537, Standard Methods; Reeve-Angel 934AH
glass fiber discs were used in place of the mats prepared by
using asbestos fibers. Filter disc is dried in aluminum tin at
103°C.
Also used filtration through a 47 mm membrane filter (0.45u) using
Millipore filter holder. Filter is dried in aluminum tin at
103°C. Only used this method for a few samples.
Biochemical Oxygen Demand - p. 489, Standard Methods; BOD tests could
often not be performed until several days after sample collection.
Raw sewage was used as a seed (1 ml volume). The dissolved oxygen
was measured by a Yellow Springs instrument DO probe, Yellow
Springs, Ohio. (Method F., p. 489 of Standard Methods.)
Alkalinity - p. 370, Standard Methods; Electrometric titration to pH 8.3
and 3.7
Total Coliform - p. 679, Standard Methods, Method A. Millipore
Membrane filter method for total coliform
Color - p. 160, Standard Methods; Helige Chromatron - comparison against
glass discs calibrated with platinum-cobalt standards
Cyanide - p. 399, Standard__M_ethods; The sample is pretreated by distilla-
tion and analyzed for cyanide by titration or colorimetrically,
depending upon the concentration.
Grease - p, 409, Standard Methods; Soxhlet extraction of a filtered
sample with hexane.
Kjeldahl Nitrogen - p. 244, Standard Methods; Digestion of the sample
followed by distillation and titration. This measures both
organic nitrogen and ammonia.
j>H - p. 276, Method A, Standard Methods, pH meter measurement using
a Bcckman Model SS2 pH meter
216
-------
Volatile Total Solids - p. 292, (Method D) and 536 (Method B),
Standard Methods; Residue and dish ignited at 550°C.
Volatile Suspended Solids - p. 292 (Method D) and p. 536 (Method B)
Standard Methods; The residue and filter from the glass fiber
filter suspended solids method are transferred to a crucible for
ignition.
Total Hardness - p. 76, WQO, EDTA titration using Hach chemical as
specified by WQO.
Ammonia Nitrogen - p. 134, WQO, Distillation at pH 9.5 followed by
Nesslerization or titration. There is more chance of measuring
some amines as Nlly with this method, but less trouble in testing
samples containing large amounts of calcium.
Total Phosphorus - p. 242, WQO, p. 231, Method A, 12th Edition,
Standard Methods, (1965). Sample is digested with persulfate
(WQO method) and phosphate measured by ANS procedure (Standard
Methods).
Sulfate - p. 286, WQO; Turbidimetric method using Hach SulfaVer.
Turbidity - p. 308, WQO; using Hach Model 2100A turbidimeter.
TOG - p. 221, WQO; Bechman Model 915 TOG analyzer.
The following analyses were performed according to the methods listed in
Analytical Methods for Atomic Absorption Spectrophotometry, Perkin Elmer
Corp. (19), equivalent to the mentioned WOO method. The digestion procedure
described on pages 86-89 of Methods for Chemical Analysis of Water and Waste
was used for all metals (18). All metals were measured by atomic absorption
spectroscopy.
Calcium - p. 102, WQO
Cadmiujn - p. 101, WQO
Total Chromium - p. 104, WQO
Copper - p. 106, WQO
Iron - p. 108, WOO
Lead - p. 110, WQO
217
-------
Magnesium - p. 112, WQO
Manganese - p. 114, WQO
Mercury - p. 121, WQO, Flameless atomic absorption
Nickel - Perkin Elmer Analytical Methods
Potassium - p. 115, WQO
Sodium - p. 113, WQO
Silicon- Perkin Elmer, Analytical Methods using the nitrous oxide flame
Zinc - p. 120, WQO
Tin - Perkin Elmer Analytical Methods
The following analyses were performed according to the procedures listed:
Specific Gravity - hydrometer
Viscosity - Brookfield viscometer
Phenol - Hach Catalog No. 10. p. 52. Chemical removal of interference
followed by treatment with 4- aminoantipyrine for color development.
Color development part is based on the following procedures:
Standard Methods, p. 504 and 507, or WQO. p. 232.
Analysis for Dissolved Matter - The analysis for dissolved matter
(i.e. BOD, TOG) was obtained by filtering the sample through a
millipore filter (0.45 u)and then performing the appropriate
analysis (BOD, TOG) on the filtrate. If the sample contained
gross amounts of solids which would rapidly blind the millipore
filter disc, the sample was prefiltered through SS-597 filter
paper. The filtrate from this prefiltraiton was then filtered
through the millipore disc as described above.
218
-------
DISSOLVED-AIR FLOTATION TEST PROCEDURE
The rate of separation of the suspended solids from a waste is useful in
the design of industrial waste treatment equipment. Rate of separation
data may be conveniently obtained in the laboratory from treatment tests
performed on the waste in question. Generally, the procedure used in
obtaining rate-of-separation data is to observe the solids-liquid interface
and record its travel with time. The test procedure for performing this
test follows.
A. Dissolved-Air Flotation
In the tests using dissolved-air flotation, the rate of rise of the
major portion of the solids is recorded. At times the solids-liquid
interface may be vague and good judgment may have to be exercised in
following this interface. Care should be taken to avoid following
the interface formed by the air bubbles alone. In general, this inter-
face lags behind the solids-liquid interface.
A suggested procedure for the performance of laboratory flotation
tests and the equipment needed is as follows:
1. Equipment
a. Flotation pressure cell
b. Graduated cylinder of one liter capacity containing an
effluent sampling nozzle.
c. Tire pump or source of compressed air
d. Gooch crucibles for suspended solids determinations
e. Stop watch
2. Flotation Test Procedure
a. Record waste temperature, pH, operating pressure, recycle
rate, and flotation detention time.
b. Record rate of separation data. The form shown below
is suggested in obtaining the rate of separation data.
The ultimate data desired is the position of the interface
at various intervals throughout the test. The column
below labeled "Volume" is used as a convenient means of
obtaining the position of the interface at any given time.
For example, in the hypothetical case shown below, a liter
graduate was used in the,test. At the beginning of the
test, the solids-liquid interface is at the bottom of the
graduate or at zero volume. As flotation progresses, the
solids-liquid interface moves progressively up the height
of the graduate. The position of the interface at any
given time may be conveniently obtained using the
219
-------
appropriate graduation mark on the liter cylinder as a
reference. After the flotation test, the graduation marks
may be converted to the actual height by measurement.
Time, Volume, POI (position of interface),
min. ml meters
00 0
1 100 0.035
2. 350 0.125
3 500 0.179
4 650 0.233
5 800 0.288
6 950 0.342
7 950 0.342
8 950 0.342
The data obtained are plotted using Time as the abscissa
and POI in meters as the ordinate.
POI
The slope of the straight line portion of the curve
represents the rate of particle rise.
During flotation it should be noted whether settling
of solids took place. Note observation.
c. Record the floated scum volume obtained immediately before
obtaining a sample of the effluent.
d. Obtain sample of effluent five minutes after flotation is
started for the appropriate analyses. Repeat the
flotation and obtain another sample of effluent for analysis
after an eight minute detention period.
e. If possible, a small portion of the floated 'scum should be
analyzed for total solids content.
220
-------
BUCHNER FUNNEL TEST PROCEDURE
The test equipment is shown in Figure B-l.
1. Moisten filter paper (Whatman #4) and place it in the Buchner funnel.
Apply a vacuum to obtain a seal. Empty water collected in filtrate
receiver.
2. Analyze the sludge to be filtered for solids content.
3. Measure a volume of sludge that will provide a 3 mm to 6 mm thick cake.
A. Select the conditioning chemicals to be utilized and add a predetermined
amount to the sludge to be conditioned. This should be reported as
pounds chemical/ton sludge dry solids.
5. Agitate the volumetric flask vigorously and allow the sludge to sit
two minutes. Always agitate the sludge approximately the same amount
for any one test series.
6. Add the sludge to the funnel and quickly apply vacuum* As soon as
vacuum is applied, start the stopwatch. A vacuum reservoir may be
needed to hold a constant vacuum.
7. Take filtrate volume readings with respect to time.
8. Continue the test until the cake cracks, or no filtrate is deposited
for a one minute interval. Usually five minutes is sufficient. Be
sure the cake edges do not shrink from the sides of the Buchner funnel.
If it does, tamp the edges of the cake to maintain a seal.
9. Sample cake for total solids.
10. Record filtrate temperature, vacuum level, and cake thickness.
11. Plot a curve of time/volume filtrate vs. volume filtrate and record
the slope of the curve. The slope recorded should include only the
linear portion of the curve.
221
-------
Vacuum
Control
Vacuum Valve
Source -^—(^—
Test
Leaf
Filtrate
Receiver
Flask
Slurry
Container
LEAF TEST EQUIPMENT
Vacuum
Control
Valve
Vacuum
Source Q0
Buchner Funnel
or
Media Test Rig
Graduated Filtrate
Receiver
7
BUCHNER FUNNEL AND MEDIA EQUIPMENT
FIGURE B-l
TEST EQUIPMENT
222
-------
12. Calculate specific cake resistance from the formula:
a = 2PA2b/uto
O
where a = specific resistance in sec /gm
P = vacuum level in gm/sq cm
A = area of Buchner funnel in sq cm
b = slope of t/v vs. v curve in sec/cm
U = viscosity in Poise
- (Cf/(100-Cf))]
Ci = initial sludge moisture (%)
Cf = moisture concentration in cake (%)
13. Repeat steps 1 through 12 for several dosages of the same chemical.
14. Plot specific resistance vs. chemical dosage. The minimum point
obtained on the curve is the optimum chemical dosage for the
chemical tested.
FILTER MEDIA SELECTION TEST PROCEDURE
1. Select a cloth for testing in accordance with information available
on chemical and physical conditions, sludge type and properties,
and parameter qualities desired.
2. Moisten the cloth and place it in a Buchner funnel. Apply a vacuum
to obtain a seal.
3. Analyze sludge sample for solids content.
4. Measure a volume of sludge equivalent to a cake thickness of 3 mm
to 6 mm.
5. Condition the sludge with the optimum chemical dosage determined from
the Buchner funnel test as described in that test procedure.
6. Add the sludge to the Buchner funnel. Apply a vacuum of about 50 cm
Hg and start the stopwatch.
7. Measure the time to collect 100 cc of filtrate, 150 cc of filtrate,
and 200 cc of filtrate. Discontinue test after 5 minutes.
8. Remove the cloth and measure cake thickness.
9. Note cake release as follows:
excellent - cake peels off medium in pieces with slight amount
of spatula aid.
223
-------
fair - cake must be taken off medium piece by piece with spatula
poor - cake will not come off -medium even with maximum spatula
use. Some solids left on medium.
10. Analyze the cake for solids content and the filtrate for suspended
soids.
11. Wash the filter cloth on both sides with an intense water spray for
5 seconds.
12. Determine if any solids are deposited in the cloth interstices by
eye or microscopic evaluation.
13. Repeat steps 1 to 12 three times utilizing the same sample medium.
14. Run a standard test on the sludge at optimum chemical dosage using
#4 Whatman filter paper and a 50 cm Hg vacuum.
VACUUM FILTER LEAF TEST PROCEDURE
The test equipment is shown in Figure B-l.
1. Condition 2-4 liters of sludge according to Buchner funnel test
results.
2. Place cloth selected from media screening test on the filter leaf
and attach leaf hose to filtrate receiver.
3. Crimp the hose connecting the leaf to the vacuum source and set
vacuum to desired level with the bleeder valve.
4. Immerse the leaf in the sludge so that the surface of the leaf is
two to three inches below the sludge level. Release the hose and
start the stopwatch simultaneously.
5. Keep the leaf submerged for a predetermined pickup time obtained
from preliminary tests. For thin sludges, move the leaf slowly
in a horizontal plane with a circular wrist movement at a rate of
6 rpm. In thick sludges, the leaf should remain stationary. Keep
thin sludges mixed with a small mixer. Thick sludges should be
thoroughly mixed prior to the test.
6. At -the end of the pickup time, the leaf is rotated out of the. bucket.
7. The leaf is then held with the cake upward for the duration of
the drying cycle. At the end of this time, vacuum is released.
Adjust the vacuum as much as needed during the dry time to maintain
vacuum level. Allow all filtrate to drain from the hose to the
filtrate receiver.
224
-------
8. Remove the cake from the filter leaf by blowing into leaf hose and
dislodging it with a spatula. Analyze the cake for total solids.
Note cake discharge and thickness.
9. Analyze filtrate for suspended solids, and record the filtrate
volume.
10. Repeat steps 1-9 twice more on the same sample to determine if the
results are reproducible.
11. Analyze solids content of remaining sludge. Two to four tests may be
run on the same sample.
Preliminary Testing
In initial tests, submerge test leafs for various periods of tine and note
at what time cake sloughing takes place, i.e. sludge will no longer
build up uniformly, but falls off when leaf is removed from bucket. This
is the maximum pickup time. The minimum pickup time is the time required
to produce a cake thick enough to discharge.
Utilizing the maximum pickup time determined above, perform a leaf test
and allow the cake to dry until it cracks or shrinks away from the edges
of the leaf. This represents the maximum drying time. Run the remainder
of the leaf tests according to steps 1-11 in the range of these established
pickup and drying times.
FLOCCULATION JAR TEST PROCEDURE
1. Measure 50 nil to 100 ml into a 100 ml graduated cylinder and add a
predetermined dosage of the chemical selected.
2. Invert the cylinder three times, keeping the palm on the top of the
cylinder. (This is rapid mix.)
3. Add any additional chemicals in the order desired and repeat step 2.
A. Gently swirl the graduated cylinder with the wrist for a predetermined
time interval. Observe the floe formation.
5. Repeat steps 1 to 4 for various chemical dosages, and compare the
graduated cylinders visually to determine optimum chemical dosage.
Floe size, supernatant clarity, and rate of floe formation all
help in determining the optimum chemical dosage.
6. Utilize any other chemicals desirable.
225
-------
DIATOMACEOUS EARTH PRECOAT VACUUM FILTRATION
BENCH TEST PROCEDURE
1. Utilize the leaf test equipment shown in Figure B-l with a suitable
cloth support medium.
2. Provide two extra pans with continuous mixing, one with a 3%
diatomaceous earth slurry and the other with a clay suspension or
suspension of other blinding substances.
3. Insert the filter leaf into the DE slurry and apply a 12 to 24 cm
Hg vacuum. Obtain a 20 mm to 40 mm thickness of DF on the test leaf.
Cut away an edge of the cake to form a circular area of a known
diameter. It will look like a small plateau above the rest of the
filter aid. This is the desired filtration surface.
4. Insert the filter leaf into the clay suspension and leave it until
no filtrate is deposited, thus blinding off the whole leaf. Scrape
away the clay from the plateau of the filter leaf with a spatula to
expose the filtration surface.
5. Perform a leaf test with this filter leaf as described in the
vacuum filter leaf test procedure beginning with step 3. Eliminate
the circular wrist movement, however, and hold the leaf stationary.
Proceed to step 7 of that procedure.
6. Measure the final filtrate volume, and scrape off the picked up solids
to expose fresh filter surface for the next test. Analyze the filtrate
for total solids and repeat steps 5 and 6.
7. Analyze the suspension0 to be filtered and filter aid cuttings for
total ash to calculate the amount of filter aid required for a large
system. Try different DE grades to optimize filtrate clarity and
filtration rate.
NOTE: Always keep a vacuum on the filter leaf to avoid losing the
precoat. Preliminary testing can be utilized to determine what
length pickup time is required.
226
-------
APPENDIX C
OPERATING DATA AND SAMPLE ANALYSES
227
-------
TABLE C-l
INDUSTRIAL LAUNDRY SURVEY WASH.WHEEL
DISCHARGE DATA
MARCH 15, 1971
N>
K)
CO
Article
Laundered
364 kgs
(800 Ibs)
Shop Towels
Operation
Flush
Suds
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Rinse 7
Rinse 8
Rinse 9
Rinse 10
Dye
Cold Rinse
Water
Volume
(liters)
1340
420
420
1340
1340
1340
1340
1340
1340
1340
1340
1340
1340
1340
1340
TOC
(ms/1)
12,500
77,000
59,000
—
24,500
13,000
8950
7500
4150
2550
1600
900
700
750
400
Total
Solids
(mg/1)
13,233.
86,175
101,045
—
42,636
31,020
15,931
11,132
7985
4660
3480
2148
1554
3797
1661
pH
(units)
8.4
12.9
13.0
12.6
12.9
12.9
12.7
12.5
12.1
12.1
11.8
11.6
10.9
10.4
Volatile
Soluble Suspended Sus.
TOC Solids Solids Supplies
(mg/1) Cmg/1) (mg/1) Added
3213 7700
X
1780
5110
X
40 455 320
kss/100 kgs
Laundered
44.6
73,1
-------
TABLE C-l, CONTINUED
INDUSTRIAL LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 15, 1971
NJ
N>
Article
Laundered
182 kgR
(400 Ibs
Printer's
Towels
Operation
Flush
Suds
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Rinse 7
Rinse 8
Rinse 9
Rinse 10
Rinse 11
Cold Rinse
Water
Volume
(liters)
655
216
216
655
.655
655
655
655
655
655
655
655
655
655
655
TOG
(mg/1)
17,750
98,000
83,500
21,500
16,400
12,300
6050
5900
1450
1000
650
400
400
225
200
Total
Solids
(mg/1)
14,64-4
88,286
81,803
40,224
25,420
16,607
11,581
6360
4134
2839
1802
1245
1005
812
663
pH
(units
7.8
13.2
13.2
13.1
12.7
12.8
12.5
12.4
12.3
12.0
11.8
11.4
10.9
10.6
10.3
kgs/100 kgs
Laundered
Volatile
Soluble Suspended Sus.
TOG Solids Solids Supplies
(mg/1) (mg/1) (mg/1) Added
8070
2150
1640
98
272
41.9
66.2
-------
TABLE C-l, CONTINUED
INDUSTRIAL LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 16, 1971
K3
OJ
o
Article
Water
Volume
TOC
Laundered Operation (liters) (mg/1)
364 kRs
(800 Iba)
Printer's
Towels
Flush1
Suds
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Rinse 7
Rinse 8
Rinse 9
Rinse 10,.
Cold RinseJ
kj»s/100 kgs
Laundered
—
1340
420
420
1340
1340
1340
1340
1340
1340
1340
1340
1340
1340
1340
—
8500
100,000
58,000
9125
9000
4150
5000
2400
1100
800
575
600
460
520
33.9
Total
Solids
lmg/1)
7444
74,180
49,258
28,136
19,574
8933
10,727
5632
3097
2282
1620
1735
1436
1231
48.2
Soluble
TOC
(MB /l)
3000
e
30,700
23,125
2063
1875
4050
1300
655
520
391
251
215
235
2000
e
11.7
PH
junits)
8.0
13.1
13.2
12.9
12.8
12.6
12.7
12.5
12.2
12.0
11.7
11.5
11.5
11.2
—
1 Grease, mg/1 - 3345
2 Alkalinity, mg/1 as CaC(>3 -
3 Grease, mg/1 - 202
7150
estimated
Silica Volatile
as Sus. Sus.
Si02 Solids Solids Supplies
(mg/1) (mg/1) (mg/1) Added
1800
2010
5040
6320
1898
1510
690
2425
910
640
420
380
295
273
580
5.75
5555 X
2085
505
-------
TABLE Ol, CONTINUED
INDUSTRIAL LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 16, 1971
NS
U)
Article
Laundered
182 ICRS
(400 Ibs)
Dust Mops
Operation
Flush
Suds
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Dye
Rinse 7
Water
Volume
(liters)
65.5
216
216
655
655
655
655
655
—
655
655
TOC
(mg/1)
990
22,500
18,000
7600
4350
2600
1750
900
—
900
768
Total
Solids
(mg/1)
3730
57,878
49,144
31,980
16,991
7033
3904
2507
—
5681
2912
Soluble Sus.
pH TOC Solids
(units) (mg/1) (mg/1)
9.0 385 1410
13.1
13.1
13.0
12.8
12.6
12,2
12.0
—P —
11.7
11.2 214 750
Volatile
Sus.
Solids Supplies
(mg/1) Adcled
1050
X
—
X
krcs/100 kp.s
Laundered
12
39.7
-------
TABLE C-l CONTINUED
INDUSTRIAL LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 16, 1971
Article
Laundered
182 kgs
(400 Ibs)
Dust Mops
N3
kps/100 kgs
Laundered
Operation
Flush
Suds1
Carryover
Rinse I2
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Dye
Rinse 7
Water
Volume
655
216
216
655
655
655
655
655
655
655
655
TOC
(me/1)
910
12,500
15,250
9800
5950
4920
2150
1460
850
650
304
Total
Solids
(ma/1)
3731
40,543
50,591
32,740
8940
10,451
6236
3291
2201
3686
1987
PH
(units)
9.0
13.2
13.1
12.9
12.8
12.7
12.4
12.1
11.9
11.3
10.9
Volatile
Sus. Bus.
Solids Solids
(mg/l) (mg/1)
1420
Soluble
TOC Supplies
(mg/1) Added
520
X
2990 2290
775
685
69
13.0
40.9
1 Alkalinity - 20,313 mg/l as CaC03
2 Grease - 2,300 mg/l as Si02
-------
TABLE C-l, CONTINUED
INDUSTRIAL LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 16, 1971
Article
Laundered
364 kRP
(800 Ibs)
Printer's
Towels
Operation
Flush
Suds
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Rinse 7
Rinse 8
Rinse 9
Rinse 10
Cold Rinse
Water
Volume
(liters)
1340
420
420
1340
1340
1340
3340
1340
3340
1340
1340
1340
1340
1340
TOC
(mg/1)
1900
45,800
43,500
8250
5250
2700
1600
570
510
480
160
140
80
236
Total
Solids
(mg/1)
7263
79,900
60,108
35,127
23,413
12,277
7850
4185
2596
1521
1224
885
625
635
PH
(units)
12.6
14.0
13.4
13.1
13.0
12.9
12.7
12.5
.12.2
11.8
11.2
10.6
10.3
10.0
Volatile
Soluble Sus. Sus.
TOC Solids Solids Supplies
(mg/1) (mg/1) (mg/1) Added
750 1385
X
694 1630
18 440 405
kgs/100 kf,s
Laundered
18.4
52.2
-------
TABLE C-l, CONTINUED
INDUSTRIAL LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 16, 1973
Article
Laundered
364 kp,s
(800 Ibs)
Shop Towels
Operation
Flush1
Suds
Carryover
Rinse I2
Rinse 2
Rinse 2
Rinse 4
Rinse 5
Rinse 6
Rinse 7
Rinse 83
Rinse 9
Dye ,
Cold Rinse
Water
Volume
(liters)
1340
420
420
1340
134P
1340
1340
1340
1340
1340
1340
1340
134C
1340
TOC
Qng/1)
18,000
43,500
30,000
13,800
4000
2000
850
730
470
810
236
136
288
194
Total
Solids
(mg/1)
51,087
86,175
80,725
38,746
13,031
8649
3368
2261
1740
1233
818
609
2252
1277
Silica
As SiOo
(tng/1)
7200
5000
3000
920
660
325
220
145
70
62
39
44
30
PH
(units)
8.3
13.0
13.1
12.7
12.5
12.3
12.0
11.6
11.2
10.6
10.4
10.1
9.9
9.7
BOD
(mg/1)
<100
7960
6825
4500
1820
900
380
200
100e
50e
50e
50e
300e
200e
Soluble
TOC Supplies
(mg/1) Added
23
X
20
X
13
kgs/100 kgs
Laundered
23.9
65.3
27.5
4.9
e
1
2
3
4
• estimated
Grease, mg/1 - 18,000
Alkalinity as CaCOs - 6300 mg/1
Suspended Solids, mg/1 - 515
Grease, mg/1 « 191
-------
TABLE C-l, CONTINUED
INDUSTRIAL LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 16, 1971
to
U>
VJ1
Article
Laundered
364 kgs
(800 Ibs)
New Wipers
Operation
Suds
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Water
Volume
(liters)
420
1340
1340
1340
1340
1340
1340
TOG
Ons/1)
4,800
3220
2720
1720
1084
652
676
Total
Solids
(mg/1)
16,227
9588
8553
5395
3388
2582
2696
PH
(units)
12.0
11.7
11.6
11.4
11.2
10.9
10.8
BOD
(mg/1)
850
305
Sus.
Solids
(mg/1)
1160
Volatile
Sus.
Solids Supplies
(mg/1) Added
kgs/100 kp,s
Lamidered
4.3
13.7
1060
X
-------
to
u>
TABLE C-l, CONTINUED
INDUSTRIAL LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 16, 1971
Article
Laundered
346 kgs
(800 Ibs)
Printer's
Towels
kgs 7100
Laundered
Operation
Flush
Sud s
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6' '
Rinse 7
Rinse 8
Rinse 9
Rinse 10
Rinse 11
Rinse 12
kgs
—
Water
Volume
(liters)
1340
420
420
1340
1340
1340
1340
1340
1340
1340
1340
1340
1340
1340
1340
1340
—
TOC
(mg/1)
3250
46,000
14,625
8500
26,200
7000
5200
3100
1820
1550
840
720
1210
550
260 .
29.3
Total
Solids
(mg/1)
56,809
50,797
24,295
17,856
23,695
9587
9530
7250
4280
4108
2799
2334
3340
1838
1177
62.0
pi!
(units)
8.9
13.2
13.0
12.9
12.9
12.7
12.7
12.4
12.3
12.3
12.1
11.9
11.9
11.5
11.4
— — •
Grease
(mg/1)
9878
166
—
Volatile
Sus. Sus.
Solids Solids Supplies
Added
X
5420
1550
1390
(1)
Soluble TOC, mg/1 - 190
-------
TABLE C-l, CONTINUED
INDUSTRIAL LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 23, 1972
Article
Laundered
364 kgs
(800 Ibs)
Printer's
Towels
Operation
Flush
Water
Volume
(liters)
1340
TOC
(mg/1)
529
Total
Solids
(mg/1)
655
pH
(units)
9.2
Suspended
Solids
(mg/1)
Supplies
Added
Is)
UJ
Suds
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Rinse 7
Rinse 8
Rinse 9
Rinse 10
Rinse 11
Rinse 12
Rinse 13
Rinse 14
420
420
1340
1340
1340
134C
1340
1340
1340
1340
1340
1340
I34n
1340
1340
1340
kgs/100 kgs
Laundered
17,350
11,400
4950
3125
3220
1690
2376
1420
1006
1082
638
696
522
477
388
268
49,600
30,252
9942
4855
3825
2190
2465
1534
1243
1159
963
585
665
695
633
303
12.6
12.40
11.85
11.8
11.65
10.9
11.2
10.6
10.2
9.95
9.65
9.6
9.45
9.4
9.3
9.1
8665
240
11.5
20.9
-------
TABLE C-2
UNIFORM LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 23, 1972
Article
Launclered
364 kgs
(800 Ibs)
Synthetic
Shirts
Ui
oo
.kgs/100 kgs
Laundered
Operation
Water
Volume
(liters)
Suds
Flush
Suds
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Sour
Starch
420
1340
420
1340
1340
1340
1340
1340
1340
420
408
TOC
(ng/1)
Total
Solids
(mg/1)
4090
1706
1822
804
350
200
130
96
66
90
3109
21,916
6990
12,755
5016
2423
1212
794
520
460
612
7515
12.35
11.95
12.75
12.4
12.1
11.75
11.25
10.4
10.1
8.1
7.55
pH
(units)
12.35
11.95
12.75
12.4
12.1
11.75
11.25
10.4
10.1
8.1
7.55
Suspended
Solids
(mg/1)
3120
86
Supplies
Added
X
X
X
X
2.3
11.4
-------
TABLE C-2, CONTINUED
UNIFORM LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 24, 1972
NJ
U)
vO
Article
Laundered
182
(400 Ibs)
White
Uniforms
kfcs/100 kgs
Laundered
Operation
Flush
Suds
Carryover
Flush
Suds
Bleach
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Sour
Water
Volume
(.liters)
655
216
216
655
216
216
655
655
655
655
655
655
216
TOG
(mg/D
127
730
636
418
449
395
510
164
94
155
132
64
48
Total
Solids
(ms/lj
535
11,984
8339
3842
3216
4264
4319
1544
766
1033
605
374
946
pH
(units)
7.9
12.8
12.7
12.45
12.3
11.75
11.65
11.2
10.5
10.6
9.5
9.5
4.3
Suspended
Solids Supplies
(tng/1) Added
147 X
X
60
X,
0.9
6.8
-------
TABLE 0-2, CONTINUED
UNIFORM LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 24, 1972
K>
4S
O
Article
Laundered
364 kgs
(800 Ihs)
Rugs
Operation
Flush
Suds
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Rinse 7
Oil Treatment
Water
Volume
(liters)
1340
420
420
1340
1340
1340
1340
1340
1340
1340
420
TOC
(mg/1)
1691
5022
7403
4826
4826
4323
3534
2098
960
373
1548
Total
Solids
(mg/1)
3927
17,266
17,704
12,250
9885
9339
8521
3318
1890
1093
3131
PH
(units)
7.35
12.65
12.65
12.50
12.35
12.3
12.25
11.8
11.3
10.6
7.9
Suspended
Solids Supplies
(mg/1) Added
4990 X
385
X
kgsII00 kgs
Laundered
9.9
22.9
-------
TABLE C-2, CONTINUED
UNIFORM LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 24, 1972
Article
Launderjed
182 k?,s
(400 Ibs)
Colored
Uniforms
Operation
Suds
Water Total Suspended
Volume TOC Solids pll Grease Solids Supplies
(liters) (mg/1) (mg/1) (units) (mg/1) (rag/1) Added
216 5034 15,931 12.5 1700 860 x
kgs/100 legs
Laundered
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Sour
Starch
216
655
655
655
655
655
655
216
132'
5344
1856
586
259
117
83
57
50
1938
12,448
4383
1888
765
429-
498
360
1684
4331
12.45
12.1
11.6
10.85
10.15
9.7
9.5
4.7
4.85
176
86
X
X
2.5
6.9
-------
TABLE C-2, CONTINUED
UNIFORM LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 24, 1973
S3
Article
Laundered
182 kf?s
(400 Ibs)
Shirts
Operation
Suds
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Sour
Starch
Volume
(liters)
216
216
655
655
655
655
655
655
216
132
TOC
(mg/1)
6314
3591
1473
875
310
336
92
64
66
2800
Solids
(mg /I)
21,112
13,916
5441
2743
1436
944
569
524
1513
7096
pH
(units)
13.1
12.95
12.55
12.2
11.9
11.3
10.5
10.05
4.9
4.9
Solids
(mg/1)
810
126
Supplies
Added
X
X
X
kgs/100 kgs
Laundered
2.5
9.2
-------
TABLE C-2, CONTINUED
UNIFORM LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 24, 1972
Article
Laundered
384
(800 Ibs)
Synthetic
Pants
to
kgs/100 kgs
Laundered
Operation
Break
Carryover
Break
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rinse 6
Sour
Starch
Water
Volume
(liters)
420
420
420
1340
1340
1340
1340
1340
1340
420
412
TOC
fag/1
6396
3520
1604
958
649
379
264
214
79
78
575
Total
Solids
(mg/D
21,783
13,429
7220
3392
1781
1763
1342
1145
534
1011
1833
PH
(units)
12.8
12.7
12.55
12.3
12.05
11.75
11.5
11.25
10.2
5.15
6.7
Grease
(mg/1)
2520
321
2.3
8.9
Sus.
Solids
(mg/1)
2780
Supplies
Added
110
X
X
-------
TABLE C-2, CONTINUED
UNIFORM LAUNDRY SURVEY,WASH WHEEL
DISCHARGE DATA
MARCH 24, 1972
Article
Laundered
Operation
Water Total Suspended
Volume TOG Solids pH Solids Supplies
(liters). (mg/1) (mg/1) (units) Qng/D Added
182 legs
(400 3bs)
Coveralls
kgs/100 kgs
Laundered
Suds
Carryover
Rinse 1
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Rin^e 6
Sour
Starch
216
216
655
655
655
655
655
-655
216
132
4,644
2948
1052
552
260
125
86
67
44
626
16,125
10,538
4250
2248
1232
797
589
469
1087
2077
12.7
12.5
12.2
11.85
11.45
10.6
10.1
9.7
4.95
6.9
2090
1214
530
376
242
173
157
128
247
446
X
X
X
1.7
6.9
1.1
-------
TABLE C-3
Article
Laundered
364 kgs
(800 Ibs)
Tablecloths
Ul
kgs/100 kgs
Laundered
LINEN LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 16, 1971
Operation
Flush
Flush
Break
Suds
Rinse 1
High Suds
Bleach
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Sour
Water
Volume
(literal
1340
1340
420
420
1340
670
420
1340
1340
1340
1340
250
TOC
-------
TABLE C-3, CONTINUED
LINEN LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MARCH 16, 1971
Article
Laundered
Operation
Flush
364 kgs
(800 Ibs)
Kitchen Tov/els Flush
Break
Suds
N> Rinse I1
£ High Suds
Bleach
Rinse 2
Rinse 3
Rinse 4
Rinse
Sour
kgs/100 kgs
Laundered
Water
Volume
(liters)
1340
TOC
1450
Total
Solids
(mg/1)
3917
pll
(units)
5.1
1340
420
420
1340
670
568e
1340
1340
1340
1340
250
700
5050
2450
820
660
510
190
104
73
78
148
1977
18,075
9626
3679
2527
3530
1314
604
514
436
847
7.9
12.6
12.3
11.9
11.5
8.4
8.9
9.2
8.7
8.9
4.5
Sus. Soluble
BOD Solids TOC
(mg/1) (mg/1) (me/1)
2410 300
Supplies
Added
X
X
X
143
125
235
X
2.3
8.9
1 Alkalinity - 1110 mg/1 as CaC03
e • estimated
-------
TABLE C-3, -CONTINUED
LINEN LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MAY 19, 1971
Article
Laundered
Operation
Water
Volume
(liters)
Total Suspended
Solids pH Solids Supplies
(mg/1) (units) (mg/1) Added
136 kgs
(300 Ibs)
Continuous
Towels
ro
Flush
Flush
Suds
Carryover
Suds
Rinse 1
Bleach
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Sour
644
644
242
242
242
644
242
644
644
644
644
242
107
151
1245
913
1205
615
716
327
218
214
161
84
435
434
5250
3912
4474
2580
2999
1569
1027
935
824
1228
6.85
8.1
12.1
12.05
11.85
11.55
11.35
10.95
10.6
10.55
10.35
4.85
...kgs/100 kgs
Laundered
112
X
X
X
1.6
6,8
-------
TABLE 03, CONTINUED
LINEN LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MAY 19, 1971
*»
oo
Article
Laundered
364 kgs
(800 Ibs)
Towels
Operation
Flush
Flush
Suds
Rinse 1
High Suds
Bleach
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Sour
kgs/100 kgs
Laundered
Water
Volume
(liters;
1340
1340
420
1340
420
420
1340
1340
1340
1340
420
TOC
Qng/1)
Total
Solids
(mg/lj
pll
(units)
2520
1100
3800e
1240
1260
685
436
263
172
176
78
9954
3297
7000e
4360
3387
2444
1465
833
521
446
666
4.95
5.1
—
12.0
11.85
10.4
10.6
10.1
9.25
9.45
4.5
Supplies
Added
X
2.8
9.3
estimated
-------
TABLE C-3, CONTINUED
LINEN LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MAY 19, 1971
Article
Laundered
Operation
Water
Volume
(liters)
Total
Solids
(mg/1)
(units)
Sus.
Solids
QnS/1)
Supplies
Added
136 kps
(300 Ibs)
Tablecloth:
kgs/.100 k
Laundered
Flush
Flush
Suds
Carryover
Suds
Rinse 1
Bleach
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Sour
644
644
242
242
242
644
242
644
644
64^'
64 4
242
445
435
2555
1550
2012
740
952
329
268
150
101
54
1034
865
9543
6341
6638
2600
2726
1276
668
483
374
801
5.85
6.4
12.3
12.35
12.0
11.8
11.9
11.25
10.7
10.1
9.9
4.5
330
X
X
X
X
2.4
8.1
-------
TABLE C-3, CONTINUED
LINEN LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MAY 19, 1971
Article
Laundered
Operation
Water
Volume
(liters)
TOC
Total
Solids
(mg/1)
PH
(units)
Supplies
Added
364
(800 Ihs)
Tablecloths
to
i/i
o
Flush
Flush
Flush*
Suds
Rinse 1
Suds
Bleach
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Sour
1340
1340
1340
420
1340
420
1340
1340
1340
1340
420
320
250
248
856
300
227
147
64
63
56
83
748
548
578
5473
1581
943
628
440
290
300
719
6.5
6.7
7.0
12.25
12.1
10.2
9.8
9.2
9.0
8.95
4.45
kp,s/100 kpjs laundered
0.7
3.0
X
X
X
* Should have been a break.
-------
TABLE C-3, CONTINUED
LINEN LAUNDRY SURVEY WASH-WHEEL
DISCHARGE DATA
MAY 20, 1971
Article
Laundered
364 kp,s
(800 Ibs)
Napkins
Ui
kgs/100 kgs
Laundered
Operation
Flush
Flush
Suds
Rinse 1
Suds
Break
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Sour
Water
Volume
(liters)
1340
1340
420
1340
420
420
1340
1340
1340
1340
420
TOC
(ma/1)
175
__
375
580
329
211
223
320
192
145
229
Total
Solids
(tng/1)
175
*•*•»
7097
4774
2404
1231
772
742
487
516
773
PH
(units)
8.1
8.95
12.7
12.6
12.2
10.8
10.15
10.1
10.55
8.65
4.3
Supplies
Added
X
0.8
4.5
-------
TABLE C-3 CONTINUED
LINEN LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MAY 20, 1971
Article
Laundered
Operation
Water
Volume
(liters)
TOC
Total
Solids
(mg/1)
pH
(units)
Bus.
Solids
(mg/1)
Supplies
Added
136 kgs
(300 Ibs)
Tablecloths
ts»
kgs/100 kgs
Laundered
Flush
Suds
Carryover
Suds ..
Rinse 1
Bleach
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Sour
644
242
242
242
644
242
644
644
644
644
644
820
2232
710
1451
12,214
6066
8.8
12.75
12.5
290
89
50
36
23
32
1113
410
211
426
163
605
11.15
10.1
9.5
9.25
8.75
4.2
1.59
6.20
385
X
440
X
estimated
-------
TABLE C-3, CONTINUED
LINEN LAUNDRY SURVEY WASH WHEEL
DISCHARGE DATA
MAY 20, 1971
N2
in
Article
Laundered
Operation
kgs/100 ko;s
Laundered
Water
Volume
(liters)
364 kgs
(800 Ibs)
Kitchen
Towels
Flush
Flush
Break
Suds
Rinse 1
High Suds
Bleach
Rinse 2
Rinse 3
Rinse 4
Rinse 5
Sour
1340
1340
—
420
1340-
420
420
1340
1340
1340
1340
420
TOG
(mg/1)
1296
480
3030
448
1140
600
164
92
44
156
10
1.4
Total
Solids
3211
1083
8004
3898
2944
2115
714
426
334
343
337
5.0
PH
(units)
7.5
8.6
12.6
12.3
12.05
10.8
10.1
9.7
9.4
9.0
4.6
Suspended
Solids
GnR/1)
ioooc
360
1895
380
745
430
110
102
43
85
9
Supplies
Added
X
1.1
estimated
-------
Ul
*•
TABLE C-4
INDUSTRIAL LAUNDRY WASTEWATER TREATMENT SYSTEM
OPERATING CONDITIONS
Parameter
CaCl2 dosage - mg/1
A-23 doaage - mg/1
Avg. Raw Flow - 1pm
Recycle - 7,
Length of run - hours
Flotation Mass Loading k^/day/so m
Average Filtrate Flow - 1pm
Print wipers - % of industrial load
7. of Time Filter Blinded
Vacuum Filtration Time - hours
Sludge Volume - 1/1000 1 raw
was te
I)E Body Feed - mg DE/mg SS
DE Pressure Buildup kp/sq cm/hr
Acid Dosage - mg/1
Overflow Rate lpm/so n
23 Jan.
4886
1.93
416
76.9
4.926
49
21
20.0
53
4.12
0.73
4.9
0
74
24 Jan.
2264
1.99
51]
74.0
5.74.0
39
—
19.4
35
4.87
0.69
3.6
213
90
Run-1
25 Jan.
5766
2.40
530
77.1
1.783
127
13
15.6
8
1.32
-
-
254
94
Run-2
25 Jan.
5804
2.37
545 .
75.0
1.660
131
44
15.6
0
1.70
0.57
8.3
-232
P6
26 Jan.
2804
3.69
606
62.5
1.689
109
28
14.8
90
1.0
0
0
-
99
-------
TABLE C-4 COWPINTJED
INDUSTRIAL LAUNDRY WASTEWATER TREATMENT SYSTEM
OPERATING CONDITIONS
Parameter
CaC^ Dosage - mg/1
A-23 Dosage - mg/1
Avg. Raw Flow - 1pm
Recycle %
S Length of Run - Hours
Ui
Flotation Mass Loading kg/day/sq m
Average Filtrate Flow., 1pm
Print Wipers - % of Industrial Load
% of Time Filter Blinded
Vacuum Filtration Time - hrs.
Sludge Volume - 1/1000 1 raw
waste
DE Body Feed - mg DE/mg SS
DE Pressure Buildup, kg/sq m/hr
Acid Dosage - mg/1
Overflow Rate, Ipm/sq m
Run 1
30 Jan.
3016
2.88
606
62.5
1.509
212
-
16.7
_
_
_
0
0
430
99
Run 2
30 Jan.
3372
1.95
484
78.1
2.920
159
19
16.7
0
2.23
20
0.81
0.2
0
87
31 Jan.
3656
1.52
435
87.0
2.540
332
12
0
0
1.89
20
0
0
0
82
9 Aug.
1660
1.30
643
59.0
3.12
299
-
-
-
0
_
2.0
0.5
-
103
20 Oct.
2040
0.50
795
47.6
4.07
-
48
-
0
3.5
5.7
-
7.2
-
118
-------
TABLE C-5
1/23/73
N>
Ul
o»
1/24/73
1/25/73
Time
11:30 AM
12:03
1:52PM
2:36
3:12
7:50AM
8:02
10:05
10:45
11:30
11:59
8:40AM
8:51
11:22
11:55
12:22PM
Scum*
Solids
(Percent)
8:12 AM 5.48
9:00 5.26
10:35 14.29
5.28
3.47
7.29
VACUUM FILTRATION OPERATING
CONDITIONS FOR INDUSTRIAL LAUNDRY WASTEWATER TREATMENT
Cycle Pickup
Time Time
(Minutes) (Minutes)
5.5
5.5
4
4
5.5
5.5
5.5
5.0
5.0
5.5
5.5
5.5
5.5
5.5
5.5
,0
,0
.0
5.
5,
5.
1.51
1.47
0.82
0.82
1.13
1.13
1.13
1.30
1.30
Vacuum
Level
(cm Hg)
61
61
64
69
61
61
61
38-51
38-51
5.0
69
69
66
66
Cake
Solids
(Percent)
45.97
53.53
27.12
26.80
40.71
31.51
25.98
15.38
19.18
32.75
27.56
27.10
28.27
30.19
29.79
29.80
26.48
30.00
37.60
Solids
Loading
Oce/sq m)
1.55
.1.23
1.77
2.44
1.06
2.17
3.00
1.78
1.29
1.05
1.86
2.49
2.24
2.17
1.86
4.90
3.10
1.91
4.62
Yield
(kg/sq m/hr)
16.9
13.3
26.5
36.6
11.6
23.7
32.7
21.3
15.5
11.
20.
27.
.4
.2
.1
2A.5
23
20
58
37
22.9
55.5
Scum Scum
Volatile Suspended
Solids-X Solids-%
3.48
2.22
2.12
2.92
5.23
6.34
-------
TABLE C-5 CONTINUED
VACUUM FILTRATION OPERATING
CONDITIONS FOR INDUSTRIAL LAUNDRY WASTEWATER TREATMENT
Date
1/26/73
1/30/73
M
Ln
1/31/73
Time
1 : 20PM
2:10
2:50
3:15
3:42
Scum*
Solids
(Percent)
2.31
2.98
Cycle
Time
(Minutes)
5.5
5.5
5.5
5.5
5.5
Pickup
Time
(Minutes)
-—
—
_
0.79
0.79
Vacuum
Level
(cm Hr;)
43-64
_
—
18
18
Cake
Solids
(Percent)
33.83
23.77
16,30
15.44
14.32
Solids
Loadine
(fcc/sq m)
1.32
1.95
2.81
1.08
1.51
Yield
kp/sq m/lir
14.5
21.2
30.6
11.8
11.9
Scum
Volatile
So lids- %
2.12
1.58
Scum
Suspended
Solids-%
2.27
2.66
1:20PM
2:21
2:25
3.24
5.5
5.5
5.5
31.21
25.78
24.56
1.51
1.91
2.31
16.5
20.8
25.2
1.88
2.99
* Composite for Day
-------
to
U1
oo
Analysis
pi!, uni ts
BOD, rag/I
TOC, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
TABLE C-6
LABORATORY ANALYSIS
FOR INDUSTRIAL WASTEWATER TREATMENT
9 AUGUST 1972
Waste Flotation System
Waste From Flotation Percent D.E. Percent
to Pit Pit Effluent Removal Effluent Removal
11.85 11.5
4950 108
2805
97.8
94.8
11.45
6300 440 93.0 320 94.7
8649 5694 34.2 5609 35.1
17
99.8
99.4
Vacuum
Floated Filter
Scum Filtrate
* mg/1 as CaC03
-------
Waste Waste
Analysis to Pit From Pit
Ca,
Mg,
Cu,
Pb,
Hg,
Cd,
Zn,
Cr,
Fe,
Ni,
Si,
mg/1
mg/1
mg/1
mg/1
Vg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
9.
35
1.
0.
8.
3.
30
.80
20
60
88
60
126
1.
00
230
Flotation System Vacuum
Flotation Percent D.E. Percent Floated Filter
Effluent Removal Effluent Removal Scum Filtrate
0.
0.
-------
Analysis
pH, units
BOD, mg/1
TOG, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
•
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
TABLE C-6, n
LABORATORY ANALYSIS
FOR INDUSTRIAL WASTEWATER/TREATMENT
20 OCTOBER 1972
Waste Flotation System
Waste From Flotation Percent D.E. Percent
to Pit Pit Effluent Removal Effluent Removal
11.7 10.9
3775 2914
3756 1663
22.8
55.7
10.65
4200 1740 58.5 123 92.3
6662 6670 0 2876 56.8
48
16
98.7
99.6
Vacuum
Floated Filter
Scum Filtrate
* mg/1 as
-------
bo
Flotation System Vacuum
Waste Waste Flotation Percent D.E. Percent Floated Filter
Analysis to Pit From Pit Effluent Removal Effluent Removal Scum Filtrate
Ca,
Mg,
Cu,
Pb,
Hg,
Cd,
Zn,
Cr,
Fe,
Ni,
Si,
mg/1
mg/1
mg/1
mg/1
Ug/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
6.10
16.50
0.45
6.80
2.25
67
1.00
252 13
0.20
0.20
0.10
0.06
0.26
0.20
1.00
94.8 33
96.7
98.8
77.8
99.1
88.4
99.7
0
86.9
-------
TABLE C-6, CONTINUKT)
LABORATORY ANALYSIS
FOR INDUSTRIAL WASTEWATER TREATMENT
23 JANUARY 1973
N>
Waste
Analysis to Pit
pH, units
BOD, mg/1
TOG, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Waste
From
Pit
10.7
710
950
5561
1184
814
566
403
190
420
Flotation
Effluent
10.4
537
670
5333
785
279
216
260
110
270
Flotation
Percent
Removal
—
24.37
29.47
4.10
33.70
65.72
61.84
35.48
—
—
D.E.
Effluent
10.9
353
380
5307
663
174
152
266
160
320
System
Percent Floated
Removal Scum
-
50.28
60.00
4.57 52798
44.00 34884
78.62 22230
73.14
34.00
-
—
Vacuum
Filter
Filtrate
2981
2664
* mg/1 as CaCo
-------
ro
Waste Waste
Aji^lvsis to Pit From Pit
Ca,
Mg,
Cu,
Pb,
Hg,
Cd,
Zn,
Cr,
Fe,
Ni,
Si,
rag/1
mg/1
mg/1
mg/1
W3/1
mg/1
rag /I
mg/1
mg/1
rag/1
mg/1
840
2.
1.
4.
3.
0.
1.
1.
3.
2.
79
20
50
50
50
35
60
15
50
50
Flotation
Effluent
Flotation
Percent
Removal
805
1.
0.
3.
1.
0.
0.
1.
0.
2.
77
00
30
30
20
30
23
43
80
00
54
80
26
65
14
85
0
77
20
2.
.55
.00
.67
.71
.29
.63
. 14
.00
53
System Vacuum
D.E. Percent Floated Filter
Effluent Removal Scum Filtrate
684
0.
0.
2.
0.
0.
<0.
1.
0.
1.
28
20
40
20
50
28
02
66
40
80
18.
90.
73.
51.
85.
20.
>98.
0
88.
28.
64.
57
91
33
11
71
00
75
57
00
56
-------
TABLE C-6, CONTINUED
LABORATORY ANALYSIS
FOR INDUSTRIAL WASTEWATER TREATMENT
24 JANUARY 1973
Analysis
Waste Flotation System
Waste From Flotation Percent D.E, Percent
to Pit Pit Effluent Removal Effluent Removal
Vacuum
Floated Filter
Scum Filtrate
to
ON
.JS
oH, units
BOD, mg/1
TOG, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
10.8
647
1020
4884
1190
649
464
511
190
380
8.7
708
1200
4058
1037
404
370
605
20
150
-
0
0
16.91
12.86
37.75
20.26
0
-
-
8.6
334
470
3937
644
129
116
142
10
140
-
48.34
53.92
19.39
45.88
80.12
75.00
72.21
-
-
34721
21150
29240 1686
1540
* mg/1 as CaC03
-------
to
Waste Waste
Analysis to Pit From Pit
Ca,
MB,
Cu,
Pb,
Hg,
Cd,
Zn,
Cr,
Fe,
Ni,
Si,
mg/1
mg/1
mg/1
ITl?/!
IT. S/l .
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
580
1.
o.
3.
1.
0.
0.
2.
6.
2.
60
20
00
20
10
55
20
50
00
47
Flotation
Effluent
300
0
0
2
1
0
0
2
2
1
.60
.40
.50
.20
.40
.35
.43
.50
.30
107
Flotation
Percent
Removal
48.28
62.50
0
16.67
0
0
36.36
0
61.54
35.00
0
D.E.
Effluent
384
0.
0.
1.
0,
0.
0.
2.
1.
1.
86
30
30
80
80
12
06
96
00
20
System Vacuum
Percent Floated Filter
Removal Scum Filtrate
33.
81.
0
40.
33.
0
89.
0
84.
40.
0
79
25
00
33
09
62
00
-------
ro
TABLE C-6, CONTINUED
LABORATORY ANALYSIS
FOR INDUSTRIAL WASTEWATER TREATMENT
25 JANUARY 1973
RUN 1
Analysis
pH, units
BOD, mg/1
TOC, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Waste
to Pit
10.9
1314
2650
7243
2749
3509
2247
1623
360
950
Was te
From Flotation
Pit Effluent
5.0
820
960
4987
991
553
524
387
0
80
Flotation System
Percent D.E. Percent
Removal Effluent Removal
-
37.60
63.43
31.15
63.95
84.24
76.59
74.14
-
-
Vacuum
Floated Filter
Scum Filtrate
10.9
72933
52327
63430 2448
2280
* mg/1 as CaC03
-------
N>
Analysis
Ca,
Mg,
Cu,
Pb,
Hg,
Cd,
Zn,
Cr,
Fe,
Ni,
Si,
mg/1
mg/1
mg/1
rag/1
Vg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
Waste Waste Flotation
to Pit From Pit Effluent
830
14
3.
14
—
0.
4.
3.
44
2.
21
.00
40
.50
12
90
55
.50
00
630
0.
0.
3.
1.
0.
0.
0.
1.
1.
68
60
50
00
20
35
60
95
50
00
Flotation System Vacuum
Percent D.E. Percent Floated Filter
Removal Effluent Removal Scum Filtrate
24.
95.
85.
79.
—
0
87.
73.
96.
50.
0
10
71
29
31
76
24
63
00
-------
TABLE C-6, CONTINUED
LABORATORY ANALYSIS
FOR INDUSTRIAL WASTEWATER TREATMENT
25 JANUARY 1973
RUN 2
Analysis
pH, units
M BOD, tag /I
00
TOC, .mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Waste
to Pit
10.7
1480
5728
1497
1655
1020
966
90
490
Waste
From
Pit
9.8
2340
3034
340
940
Flotation
Effluent
9.25
1167
2080
5276
1357
614
498
953
45
210
Flotation
Percent
Removal
—
11.11
7.89
9.35
62.90
51.18
1.35
D.E.
Effluent
8.65
319
430
4097
720
142
86
123
10
170
Sys tern
Percent
Removal •
_
72.66
70.95
28.47
51.90
91.42
91.57
87.27
Vacuum
Floated Filter
Scum Filtrate
2894
2816
* mg/1 as CaC03
-------
Ox
VO
Analysis
Ca,
Mg,
Cu,
Pb,
Hg,
Cd,
Zn,
Cr,
Fe,
Ni,
Si,
rag/1
mg/1
mg/1
mg/1
yg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
Flotation
Waste Waste Flotation Percent
to Pit From Pit Effluent Removal
590
5.
2.
8.
—
<0.
2.
3.
17
1.
21
80
50
50
05
15
00
.00
00
465
0.
0.
2.
—
0.
0.
1.
1.
1.
84
50
90
30
20
38
93
30
00
21.19
91.38
64.00
72.94
—
0
82.33
35.67
92.35
0
0
System Vacuum
D.E. Percent Floated Filter
Effluent Removal Scum Filtrate
440
0.
0.
2.
1.
0.
0.
1.
0.
1.
81
40
70
00
20
35
10
95
50
00
25.
9.3.
72.
76.
—
0
95.
35.
97.
0
0
42
10
00
47
35
00
06
-------
r-o
•^j
o
Analysis
pH, units
BOD, mg/1
TOC, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
TABLF C-6, CONTINUED
LABORATORY ANALYSIS
FOR INDUSTRIAL WASTEWATER TREATMENT
26 JANUARY 1973
Waste Flotation
Waste From Flotation Percent D.E.
Sys tern
Percent
to Pit Pit Effluent Removal Effluent Removal
Vacuum
Floated Filter
Scum Filtrate
10.1 10.85
692 725
1380 1110
4856 3953
1422 1129
1810 408
985 320
725 763
120 265
600 450
0
19.57
18.60
20.60
77.46
67.51
0
26434
15283
22700
2121
2095
* mg/1 as CaCO-
-------
NJ
Waste Waste
Analysis to Pit From Pit
Ca,
Mg,
Cu,
Pb,
Hg,
Cd,
Zn,
Cr,
Fe,
Ni,
Si,
mg/1
mg/1
mg/1
mg/1
W 5/1
mg/1
mg/1
mg/1
rag/1
mg/1
mg/1
400
5.
1.
6.
—
0.
1.
1.
16
1.
60
15
50
00
no
65
00
.00
00
Flotation
Effluent
220
0
0
2
-
0
<0
1
1
1
.40
.90
.50
-
.25
.02
.40
.00
.00
128
Flotation System Vacuum
Percent D.E. Percent Floated Filter
Removal Effluent Removal Scum Filter
45.
92.
40.
58.
— "
0
98.
0
93.
0
0
00
23
00
33
79
75
-------
NJ
Analysis
pH, units
BOD, mg/1
TOC, mg/1
Total Solids, rag/1
Vol. Total Solids, rag/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
TABLE C-6, CONTINUF.D
LABORATORY ANALYSIS
FOR INDUSTRIAL WASTEWATER TREATMENT
30 JANUARY 1973
RUN 1
Waste Flotation
Waste From Flotation Percent D.E.
to Pit Pit Effluent Removal Effluent
Sys tern
Percent
Removal
Vacuum
Floated Filter
Scum Filtrate
10.45 10.45
1160 154
390 163
1240 185
86.0
9.80
1620 370
6246 3452
77.2
44.7
450
3130
72.2
49.9
19
150
208
98.4
* mg/1 as CaCO-j
-------
TABLE C-6, CONTINUED
LABORATORY ANALYSTS
FOR INDUSTRIAL VJASTEWATER TREATMENT
30 JANUARY ]f>73 - RUN 2
N)
*vl
Analysis
pH, units
BOD, mg/1
TOC, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, rag/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pll 8.3*
Alkalinity to pH 3.7*
Waste
to Pit
10.2
943
1700
6061
1846
2625
1425
1163
315
930
Was te
From Flotation
Pit Effluent
10.1
313
460
3610
635
236
161
185
90
220
Flotation
Percent
Removal
-
66.81
72.94
40.44
65.60
91.01
88.70
84.09
D.E.
Effluent
10.6
1574f
1820*
3555
711
20
13
82
115
220
System
Percent
Removal
-
-
-
41.35
61.48
99.24
99.09
92.95
Vacuum
Floated Filter
Scum Filtrate
29849
15779
26640 1262
1219
* mg/1 as CaC03
t Organic Sample Contamination
-------
TABLE C-6, CONTINUED
LABORATORY ANALYSIS
FOR INDUSTRIAL WASTRWATER TREATMENT
30 JANUARY 1973 - RUN 2
Analysis
Ca,
Mg,
Cu,
Pb,
Hg,
Cd,
Zn,
Cr,
Fc,
Ni,
Si,
mg/1
rag/1
mg/1
mg/1
US/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
Flotation
Waste Waste Flotation Percent D.E.
to Pit From Pit Effluent Removal Effluent
710
8.
2.
9.
7.
<0.
3.
1.
25
1.
5
8
5
0
05
A
5
0
385
0.
0.
0.
0.
0.
0.
1.
0.
0.
1
5
6
6
01
17
2
8
3
82.1
93.7
91,3
80
95
20
96.8
70
System Vacuum
Percent Floated Filter
Removal Scum Filtrate
360
0.
0.
0.
0.
0.
0.
1.
0.
0.
08
AO
50
60
01
02
3
7
3
85.
9A.
91.
80
99.
20
97.
70
7
7
3
A
2
-------
TABLE C-6, CONTINUED
LABORATORY ANALYSIS
FOR INDUSTRIAL WASTEWATER TREATMENT
31 JANUARY 1973
NJ
Analysis
Waste Flotation
Waste From Flotation Percent
to Pit Pit Effluent Removal
System
D.E. Percent
Effluent Removal
Vacuum
Floated Filter
Scum Filtrate
pH, units
BOD, rag/1
TOG, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
11.20
2660
3303
2265
540
1080
10.8
677
4200
8538
3747
5495
3495
2979
530
1380
10.7
566
1040
3896
1855
550
460
-
130
350
-
17.87
75.59
54.37
50.49
89.99
86.84
-
0
_
32403
18796
29930
mg/1 as CaCO.,
-------
N>
-si
TABLE C-6, CONTINUED
LABORATORY ANALYSIS
FOR INDUSTRIAL WASTEWATER TREATMENT
31 JANUARY 1973
Waste Waste
Analysis to Pit From Pit
Ca,
Mg,
Cu,
Pb,
Hg,
Cd,
Zn,
Cr,
Fe,
Ni,
Si,
mg/1
mg/1
mg/1
mg/1
ug/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
300
21
6.20
20.50
—
0.20
6.80
3.20
72
1.00
—
Flotation System Vacuum
Flotation Percent D.E. Percent Floated Filter
Effluent Removal Effluent Removal Scum Filtrate
270
0.
1.
0.
—
0.
0.
1.
1.
0.
—
90
50
80
02
44
60
00
60
10.
95.
75.
96.
—
90.
93.
50.
98.
40.
—
00
71
81
10
00
53
00
61
00
-------
M
•vj
TABLE C-7
UNIFORM WASTE TREATMENT SYSTEM
OPERATING CONDITIONS
Parameter
CaCl2 Dosage - mg/1
A-23 Dosage - mg/1
Avg. Raw Flow - 1pm
Recycle - %
Length of run - hours
Total wastewater volume treated -
cu m
Filtrate Flow - 1pm
% Filter Blinded
Sludge Volume - 1/1000 1 raw
waste
Filter Time - hours
DE Body Feed - mg DE/mg SS
DE Pressure Buildup, kg/sq cm/hr
Flotation Mass loading, kg/day/sq
Overflow Rate, Ipm/sq m
* Print wiper contamination
2 Feb.
2132
2.73
500
82.1
3.05
91.4
53
0
14.3 est.
-
m 128
91
6 Feb.
2316
397
103.2
2.77
66.1
51
0
16.2
1.12
18
84
7 Feb.*
3193
3.43
303
135.6
1.47
26.7
-
0
41.7
1.41
-
72
8 Feb.
3506
0.27
288
142.5
0.78
13.5
76
0
27.1
0.45
18
70
9 Feb.
6991
2.37
541
75.4
1.71
55.5
58
0
13.5
0.99
126
95
Run 1
13 Feb.
1578
1.98
541
75.4
1.35
43.9
56
0
11.4
0.85
95
Run 2
13 Feb.
2454
2.88
416
98.2
2.42
60.5
37
10%
10.7
1.96
3.0
0.5
53
83
-------
TABLE C-8
VACUUM FILTRATION OPERATING
CONDITIONS FOR UNIFORM LAUNDRY WASTEWATER TREATMENT
Date
2/2/73
2/6/73
to
oo
2/7/73
2/8/73
2/9/73
2/13/73
Time
12:27 pm
12:31
12:10 pm
12:45
1:30
2:11 pm
2:27
3:10
2:35 pm
12:35 ppi
1:25
11:30-1
11:55-1
3:18-2
Scum*
Solids
(Percent)
1.52
2.15
2.63
3.53
2.49
1.19
Cycle
Time
(Minutes )
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
Pickup
Time
(Minutes )
0.80
0.85
1.62
_
-
1.62
1.03
1.40
-
1.46
1.46
1.28
1.62
1.28
Vacuum
Level
(in HR)
_
-
„
_
-
51
51
38-56
-
30-38
-
28-41
25-51
-
Cake
Solids
(Percent )
19.72
19.75
14.20
10.66
11.01
14.58
13.13
15.20
16.70
13.69
15.81
14.60
17.17
18.79
Solids
Loading
(k£/sq ra)
1.18
1.33
1.04
1.41
0.90
0.89
1.30
1.10
1.32
1.09
1.08
1.03
0.78
0.60
Yield
(kg/sq m/hr)
12.8
14.5
11.3
15.4
9.8
9.7
14.2
12.0
14.4
11.9
11.8
11.3
8.5
6.6
Scum*
Volatile
Solids- %
0.482
0.567
1.104
1.660
0.736
0.249
Scum*
Suspended
Solids- %
1.23
1.61
2.16
2.99
1.88
0.52
Daily Composite Sample
-------
TABLE C-9
LABORATORY ANALYSIS
FOR UNIFORM WASTEWATER TREATMENT
2 FEBRUARY 1973
Analysis
Waste Flotation System
Waste From Flotation Percent D.E. Percent
to Pit Pit Effluent Removal Effluent Removal
Vacuum
Floated Filter
Scum Filtrate
K>
-J
VO
ptl, units
BOD, mg/1
TOC, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3-7*
10.45
—
600
4266
1246
1765
705
180
545
1050
10.9
—
570 5
3531 17.23
769 38.28
185 89.6
161 77.16
224 0
275
430
151588
4822
12310 150
199
2326
as CaCO-
-------
TABLE C-9, CONTINUED
LABORATORY ANALYSIS
FOR UNIFORM WASTEWATER TREATMENT
6 FEBRUARY 1073
Waste Flotation
Analysis
pH, units
N, BOD, rag/1
00
o
TOC, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Suspended Solids,
mg/1
Grease, mg/1
Alkalinity to pH 8,3*
Alkalinity to pH 3.7*
Waste From
to Pit Pit
11.2
192
460
2801
985
316
233
173
695
1045
Flotation Percent
Effluent Removal
9.0
234 0
460 0
5550 0
1064 0
243 23.1
166 28.75
177 0
25
195
System
n.E. Percent Floated
Effluent Removal Scum
21457
5674
16060
2042
Vacuum
Filter
Filtrate
204
139
* mg/1 as CaC03
-------
TABLE C-9, CONTINUED
LABORATORY ANALYSIS
FOR UNIFORM WASTEWATER TREATMFNT
6 FEBRUARY 1973
ro
oo
Analvsis
Ca,
Mg,
Cu,
Pb,
Hg,
Cd,
Zn,
Cr,
Fe,
Ni,
Si,
mg/1
mg/1
mg/1
mg/1
ug/l
mg/1
mg/1
rag/1
mg/1
mg/1
mg/1
Waste Waste Flotation
to Pit From Pit Effluent
22
5
0
3
3
0
7
0
2
1
2
.5
.85
.7
.0
.13
.8
.17
1
.0
32
Flotation Svstem Vacuum
Percent D.E. Percent Floated Filter
Removal Effluent Removal Scum Filtrate
670
0.
0.
1.
0.
0.
n.
0.
i.
0.
42
28
42
0
8
01
65
11
11
90
94.
50.
73.
73.
92.
91.
35.
Q4.
10.
81.
9
6
0
3
3
7
3
7
0
9
-------
TABLE C-9, CONTINUED
LABORATORY ANALYSIS
FOR UNIFORM WASTEWATER TREATMENT
7 FEBRUARY 1973 t
00
N>
Analysis
pH, units
BOD, mg/1
TOC, rag/1
Total Solids, tng/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Waste Flotation System
Waste From Flotation Percent D.E. Percent
to Pit Pit Effluent Removal Effluent Removal
12.4
Vacuum
Floated Filter
Scum Filtrate
3480
7761
1700
51.2
1888
2265
750
60.27
26303
11035
21630
215
163
* mg/1 as CaC03
t Print wiper contamination
-------
TABLE C-9, CONTINUED
LABORATORY ANALYSIS
FOR UNIFORM WASTEWATER TREATMENT
8 FEBRUARY 1973
00
u>
Analysis
Waste Flotation
Waste From Flotation Percent
to Pit Pit Effluent Removal
System
D.E. Percent
Effluent Removal
Vacuum
Floated Filter
Scum Filtrate
pH, units
BOD, mg/1
TOG, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pK 3.7*
Ca, mg/1
11.65
473
765
3775
1531
437
299
369
945
1365
1180
11.8
449
570
5974
539
130
60
242
735
890
—
5.1
5.5
0 35332
64.8 16624
70.3 29890 150
79.9 119
34,4 10134
* mg/1 as
-------
TABLE C-9, CONTINUED
LABORATORY ANALYSIS
FOR UNIFORM WASTEWATER TREATMENT
9 FEBRUARY 1973
A nalysis
pH, units
BOD, mg/1
» TOG, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Waste
to Pit
9.85
295
400
6967
1275
1610
528
122
255
820
Waste
From Flotation
Pit Effluent
10.35
227
335
6547
1108
67
64
107
145
245
Flotation
Percent
Remova 1
—
23.1
16.3
6.0
13.1
95.8
87.9
12.3
System Vacuum
D.E. Percent Floated Filter
Effluent Removal Scum Filtrate
24935
7356
18800 95
78
* mg/1 as CaC03
-------
TABLE C-9, CONTINUED
LABORATORY ANALYSIS
FOR UNIFORM WASTEWATER TREATMENT
13 FEBRUARY 1973
Analysis
pH, units
BOD, mg/1
o> TOC, mg/1
Total Solids, rag/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Crease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Waste
to Pit
10.9
228
540
3268
1011
885
313
324
675
1100
Was te
From Flotation
Pit Effluent
9.70
240
435
6900
759
218
120
198
115
250
Flotation
Percent
Removal
—
0
19.4
0
24.9
75.4
61.7
38.9
D.E.
Effluent
9.65
124
225
4443
757
30
27
26
110
185
Sys tern
Percent
Removal
—
45.6
58.3
0
25.1
96.6
91.4
92.0
Vacuum
Floated Filter
Scum Filtrate
11925
2485
5220 113
69
834
* rng/1 as CaC03
-------
TABLE C-9, CONTINUED
LABORATORY ANALYSIS
FOR UNIFORM WASTEWATER TRF.ATMENT
13 FEBRUARY 1973
Analysis
Ca,
Mg,
ts>
00 Cu.
o» *
Pb,
Hg,
Cd,
Zn,
Cr,
Fe,
Ni,
Si,
mg/1
mg/1
mg/1
mg/1
W?/l
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
Raw Raw
Waste Waste Flotation
to Pit From Pit Effluent
163
9,
7.
6.
4.
0.
6.
1.
72
1.
80
90
50
30
15
20
60
.00
00
216
Flotation
Percent
Removal
1675
1.
0.
1.
0.
0.
0.
0.
1.
1.
52
20
42
60
60
02
43
17
70
10
87
94
75
86
86
93
89
97
75
0
.8
.7
.4
.0
.7
.1
.4
.6
0
.9
System Vacuum
D.E. Percent Floated Filter
Effluent Removal Scum. Filtrate
860
1.
98.
86.
86.
86,
99.
93.
98.
30.
70.
4
7
2
0
7
5
1
'
0
8
-------
TABLE C-10
LINEN LAUNDRY WASTE TREATMENT SYSTEM
OPERATING CONDITIONS
Parameter
CaCl dosage - mg/1
A-23 dosage - mg/1
Avg. Raw Flow - IP™
Recycle - %
s> Time of Run - hours
00
Solids Loading - kgs/day/sq m
Total wastewater volume treated -cu
Filtrate flow - 1pm
Sludge volume - 1/1000 1 raw waste
Filter time - hours
Wash load - k£s linen
DE Pressure Buildup, kg/sq cm/hr
Overflow Rate, Ipm/sq m
Run 1
20 Feb.
1728
2.30
459
89.0
2.40
15
m 66.1
70
18.3
0.89
1909
—
87
Run 2
20 Feb.
1375
2.67
484
84.4
1.84
8
53.5
70
6.2
0.68
1909
—
90
21 Feb.
2044
1.94
471
86.7
2.17
7
61.4
84
3.0
0.62
2909
—
88
22 Feb.
2195
1.37
473
86.4
3.14
19
90.9
120
—
0.49
3273
—
89
23 Feb.
1464
1.54
492
83.1
4.22
16
121.3
71
4.6
1.41
3455
—
90
27 Feb.
1956
1.58
517
79.2
1.695
49
52.5
87
3.0
0.46
4000
0
93
28 Feb.
2604
1.70
503
79.07
2.065
60
62.3
81
7.0
0.70
4182
0.09
90
-------
TABLF. C-10, CONTINUED
LINEN LAUNDRY WASTE TREATMENT SYSTEM
OPERATING CONDITIONS
00
CO
Parameter
CaClo dosage - rag/1
A-23 Dosage - mg/1
Avg. Raw Flow - 1pm
Recycle %
Time of Run - hours
Solids loading, kps/day/sq m
Total wastewater volume treated- cu
Filtrate Flow - 1pm
Sludge volume- 1/1000 1 raw waste
Filter time - hours
Wash load - kps linen
DE pressure buildup, kg/sq cm/hr
Overflow Rate, Ipm/sq m
Run 1
1 Mar.
2821
1.68
517
79.0
2,61
14
m 81.0
90
4.4
0.79
2294
—
90
Run 2
1 Mar.
2571
1.65
492
83.1
1.94
5
57.3
95
4.6
0.53
1706
0.20
90
14 Mar.
1784
1.68
488
83.8
3.19
19
93.4
96
1.4
0.215
4182
<0.07
90
Run 1
15 Mar.
1888
1.58
498
82.0
2.00
62
59.8
78
1.5
0.15
1585
—
91
Run2
15 Mar.
1295
2.35
495
82.6
2.36
63
70.1
86
3.9
0.74
1870
0.07
91
16 Mar.
787
0.78
467
87.5
2.90
50
81.3
92
3.9
0.67
4545
0.90
88
20 Mar.
1017
2.18
447
91.5
3.15
70
84.5
67
2.8
0.31
4364
86
-------
TABLE C-10, CONTINUED
LINEN LAUNDRY WASTE TREATMENT SYSTEM
OPERATING CONDITIONS
Parameter
CaC^ dosage - mg/1
A-23 Dosage - mg/1
Avg. Raw Flow - 1pm
Recycle - %
Time of Run - hours
Solids loading-, kgs/day/sq m
Total wastewater volume treated- cu
Filtrate flow - 1pm
Sludge volume- 1/1000 1 raw waste
Filter time - hours
Wash load - kps linens
DE pressure Buildup -kgs/sq cm/hr
Overflow Rate, lpm/sq m
21 Mar.
1526
1.54
463
88.2
2.19
299
m 60.7
92
22.1
1.1
2909
—
88
22 Mar.
1419
1.58
416
98.4
3.24
92
80.8
76
20.2
1.28
2909
—
83
23 Mar.
1455
1.39
509
80.3
1.71
76
51.9
92
6.4
0.34
3273
0.05
92
28 Mar.
2385
1.28
448
91.27
4.43
51
119.0
130
1.7
0.87
3636
0.16
86
29 Mar.
2385
1.91
310
132.00
2.45
25
45.5
08
0.47
3091
0.26
72
19 April
1570
0.83
497
82.3
1.83
159
54.5
0.23
4364
1.52
91
-------
VACUUM FILTRATION OPFRATINO
CONDITIONS FOR LINEN LAUNDRY WASTEWATER TREATMENT
Date
2/20/73
2/20/73
2/21/73
2/22/73
K>
VO
0 2/23/73
2/27/73
2/28/73
Time
11:20 am
12:30 pm
1:05 pm
1:45
12:59 pm
2:00
6:57 am
9:30
10:19
10:50
1:28 pm
1:00 pm
1:45
11:03 am
11:10
12:00 pm
Scura
Solids
(percent)
1.251
1.322
0.5514
0.7022
0.8643
1.0489
1.4965
Cycle
Time
(minutes)
5.5
5.5
5.5
5.5
5.5
5.5
^^
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
Pickup
Time
(minutes)
0.874
0.550
1.045
0.550
0.687
—
^^
—
0.935
0.550
0.825
— —
0.550
0.852
1.265
0.660
0.660
Vacuum
Level
(cm Hg)
43
30-38
43
43
43
—
_^
—
51-64
46
51-64
—
38
38
__
—
—
Cake
Solids
(percent)
17.02
20.98
26.55
12.56
15.03
19.81
__
29.06
—
__
23.77
22.46
27.12
31.27
15.20
20.00
21.80
Solids
Ix>ad inp
(kg/sq m)
2.97
2.05
1,23
0.61
0.35
0.68
_ ._
0.60
1.06
0.84
1.18
1.11
0.85
1.09
1.64
0.91
0.94
Yield
(kg/sq m/hr)
32.4
22.4
13.4
6.7
3.8
7.5
,_, mi
6.5
11.5
9.2
12.9
12.1
9.3
11.9
17.7
9.9
10.3
Scum
Volatile
Solids-%
0.4917
0.4988
0.2074
0.2682
0.3209
0.4006
0.5495
Scum
Suspended
Solids-%
0.8820
1.0175
0.2230
0.3800
0.5015
0.5240
0.9890
-------
3/29/73
4/19/73
3/1/73
3/1/73
3/14/73
3/15/73
3/15/73
£ 3/16/73
3/20/73
3/21/73
3/22/73
3/23/73
3/28/73
0.6176
4.760
7:35 am 0.9856
8:06
8:49
9:35
12:00 pm 1.3069
2:50
11:45 am 1.7400
10:32 am 0.9300
11:15
12:35 pm 1.3800
1:00
10:35 am 1.1900
11:15
2:30 pm 3.9263
9:48 pm 1.3642
10:03
10:51
11:30 am 2.1827
1:50 pm
12:30 pm 1.9407
1:00
2:15
1.1200
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
—
—
0.880
0.907 51
0.907 51
0.660
0.715 51
0.715 38
1.375
—
—
—
—
1.265
0.715
0.660
—
— —
—
—
—
24.63
22.76
22.37
23.69
26.76
26.15
27.32
24.26
23.96
23.25
24.97
26.45
22.78
13.34
12.15
13.91
15.44
16.55
13.98
11.92
11.56
13.86
25.28
27.90
—
—
0.76
0.72
1.44
1.14
1.53
1.03
1.62
1.39
1.38
0.85
0.89
1.01
1.23
1.00
3.06
0.96
0.89
1.65
2.15
1.18
1.53
0.86
0.65
0.56
—
—
8.3
7.8
15.8
12.4
16.7
11.2
17.6
15.2
15.0
9.3
9.7
11.0
13.5
10.9
33.4
10.5
9.8
18.0
23.4
12.8
16.6
9.4
7.1
6.1
0.1070
2.3900 4.1200
0.2898 0.5310
0.4322 0.8090
0.6660 1.2600
0.3630 0.6130
0.5300 1.1600
0.4100 1.0400
1.4472 1.1663
0.9690 1.0388
2.1796 1.6288
1.5522 1.4392
0.3870 0.7510
-------
TABLE C-12
LABORATORY ANALYSTS
FOR LINEN WASTEWATER TREATMENT
20 FEBRUARY 1073
RUN 1
Anal vsis
pll, units
ROD, mp,/l
TOC, mR/1
Total Solids, mo/1
Vol. Total Solids, mp,/l
S »R ponded Solid??, mp, / 1
Vol. Sun. Solids, me; /I
Ci ronse, mp/1
Alkalinity to nH 3.3*
Alkalinltv to nil 3.7*
Waste
to Pit
11.0
544**
430
1800
788
230
210
103
300
6RO
Waste
From Flotation
Pit Effluent
9.95
118
113
3277
537
63
34
326 14
100
180
Flotation System
Percent D.E. Percent
Removal Effluent Removal
—
78.31
73.72
0
31.85
72.61
84.47
02.75
Vacuum
Floated Filter
Scum Filtrate
12509
4017
8820 126
69
* mp/1 «« C.iCO-j
•'•* measured as 6 clay HOD, calculated 5 dav BOD usinp K = 0.1
-------
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
20 FEBRUARY 1973
RUN 2
Analysis
pH, units
BOD, mg/1
TOG, mg/1
Total Solids, mg/1
M Volatile Total Solids, mg/1
VO
Suspended Solids, mg/1
Volatile Suspended Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pi. 3.7*
Waste
to Pit
11.52
150**
289
1601
537
110
107
65
620
845
Waste Flotation
From Pit Effluent
980
126
125
3202
489
41
37
219 32
110
196
Flotation D.E. System Floated Vac. Flit.
% Removal Effluent % Removal Scum Filtrate
—
16.12
56.75
0 13221
8.94 4988
62.73 10175 87
65.42 54
80.6
* mg/1 as CaC03
** measured as 6 day BOD, calculated 5 day BOD using K - 0.1
-------
TABT.E C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
21 FEBRUARY 1973
Analysis
PH, units
BOD, mg/1
TOC, mg/1
S Total Solids, mg/1
Volatile Total Solids, mg/1
Suspended Solids, mg/1
Volatile Suspended Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Waste
to Pit
10.02
205**
272
919
496
106
98
85
123
285
Waste Flotation
From Pit Effluent
9.90
195
202
2983
562
81
61
88 52
99
190
Flotation D.E. System Floated Vac. Filt.
% Removal Effluent % Removal Scum Filtrate
—
5.03
25.74
0 5514
0 2074
23.58 2230 102
37.76 87
38.82
* mg/1 as CaCO-j
** Measured as 6 day BOD, calculated 5 day BOD using K - 0.1
-------
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
22 FEBRUARY 1973
Analysis
pll, units
BOD, mg/1
TOG, mg/1
Total Solids, mg/1
Jo Volatile Total Solids, mg/1
Suspended Solids, rag/1
Volatile Suspended Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to ph 3.7*
Waste
to Pit
—
797**
680
2312
1180
282
280
286
—
— —
Waste Flotation
From Pit Effluent
9.85
171
139
3295
627
87
54
191 53
109
200
Flotation D.E. System Floated Vac. Filt.
% Removal Effluent % Removal Scum Filtrate
—
78.55
79.56
0 7022
46.86 2682
69.15 3800 101
80.71 60
81.47
* mg/1 as CaCO-
** measured as 6 day BOD, calculated 5 day BOD using K - 0.1
-------
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
23 FEBRUARY 1973
Analysis
pH, units
BOD, mg/1
TOG, mg/1
Total Solids, mg/1
s> Volatile Total Solids, mg/1
Suspended Solids, mg/1
Volatile Suspended Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Waste
to Pit
11.5
178**
214
1889
549
222
141
55
685
920
Waste Flotation
From Pit Effluent
9.95
107**
119
2977
606
47
37
201 44
120
210
Flotation D.E. System Floated Vac. Filt.
% Removal Effluent % Removal Scum Filtrate
40.00
44.39
0 8643
0 3209
78.83 5915 99
73.76 55
20.00
* mg/1 as CaC03
** measured as 6 day BOD, calculated 5 day BOD using K - 0.1
-------
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
27 FEBRUARY 1973
Analysis
pH, units
BOD, mg/1
hO
^ TOG, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pii 3.7*
Ca, mg/1
* mg/1 as CaC03
Waste
to Pit
9.80
599
375
2518
835
654
400
363
170
400
Waste
From Flotation
Pit Effluent
8.85
287
205
4473
710
106
89
965 110
45
195
1185
Flotation System
Percent D.E. Percent
Removal Effluent Removal
52.09
45.33
0
14.97
83.79
77.75
69.70
Vacuum
Floated Filter
Scum Filtrate
10489
4006
5240 145
82
-------
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
28 FEBRUARY 1973
Analysis
pH, units
BOD, mg/1
£ TOO, mg/1
00
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Ca, mg/1
* mg/1 as CaC03
Waste
Waste From
to Pit Pit
10.65
181
305
3655
882
826
334
242
440
700
1275
Flotation System
Flotation Percent
Effluent Removal
9.70
226 0
169 44.59
4398 0
863 2.15
73 91.16
60 82.03
90 62.81
100
205
D.E. Percent Floated
Effluent Removal Scum
10.0
151 16.57
110 63.93
4333 0 14965
813 7.82 5495
108 86.92 9860
44 86.83
37 84.71
110
180
Vacuum
Filter
Filtrate
98
64
-------
vO
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
1 MARCH 1973
RUN 1
Analysis
pH, units
BOD, mg/1
TOG, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Ca, mg/1 ,
* mg/1 as CaC03
Waste
to Pit
10.60
216
236
1176
411
180
165
140
285
475
Waste
From Flotation
Pit Effluent
9.72
149
121
4470
650
106
53
68
110
278 200
990
Flotation System
Percent D.E. Percent
Removal Effluent Removal
31.02
48.73
0
0
41.11
67.78
51.43
Vacuum
Floated Filter
Scum Filtrate
9856
2898
5310 91
44
-------
o
o
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
1 MARCH 1973
RUN 2
Analysis
pH, units
BOD, mg/1
TOC, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Ca, mg/1
Si, mg/1
* mg/1 as CaC03
Waste
To Pit
9.80
177
156
4389
749
76
50
58
110
195
843
5
Waste
From Flotation
Pit Effluent
9.70
169
138
4194
704
116
58
69
115
200
1000 824
55
Flotation
Percent
Removal
0
11.54
4.44
6.01
0
0
0
0
0
2.25
D.E.
Effluent
9.70
113
108
2570
475
75
31
48
100
180
System
Percent Floated
Removal Scum
36.16
30.77
41.44 13069
36.58 4322
34.37 8090
38.00
17.24
9.09
7.69
Vacuum
Filter
Filtrate
144
109
-------
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
14 MARCH 1973
Waste Flotation
Analysis
pH, units
BOD, rag/1
w TOG, rag/1
|_j
Total Solids, rag/1
Vol. Total Solids, rag/1
Suspended Solids, mg/1
Vol. Sus. Solids, rag/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Turbidity, FTU
* mg/1 as CaCO-j
Waste From
To Pit Pit
11.3
97
352
2050
720
264
195
242
520
805
360
Flotation Percent
Effluent Removal
10.0
83 14.43
90 74.43
2980 0
650 9.72
78 70.45
36 81.54
73 69.83
130
220
70
System
D.E. Percent Floated
Effluent Removal Scum
9.6
56 42.27
38 89.20
2570 0 17400
475 34.03 6660
24 90.91 12600
16 91.79
50 79.34
90
161
15
Vacuum
Filter
Filtrate
102
44
-------
Analysis
pH, units
BOD, mg/1
o TOG, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Crease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Turbidity, FTU
* mg/1 as CaC03
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
15 MARCH 1973
RUN 1
Waste
Waste
Waste
From
Pit
9.9
448
320
4430
1030
862
389
234
175
450
500
Flotation
Effluent
9.95
383
281
3390
940
63
50
44
103
210
75
Flotation System
Percent D.E. Percent
Removal Effluent Removal
14.51
12.19
23.48
8.74
92.69
87.15
81.20
Vacuum
Floated Filter
Scum Filtrate
9300
3630
6130 53
48
56
-------
W
o
TARLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
15 MARCH 1973
RUN 2
Analysis
pH, units
BOD, mg/1
TOG, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Turbidity, FTU
* mg/1 as CaC03
Waste
Waste From
to Pit Pit
10.6
307
256
3410
880
874
323
202
360
632
650
Flotation
Effluent
10.45
138
111
2730
560
52
42
44
145
240
52
Flotation
Percent
Removal
55.05
56.65
19.94
36.36
94.05
87.00
78.22
D.E.
Effluent
10.30
122
103
2720
520
26
24
42
135
210
20
Sys tern
Percent
Removal
60. 26
59.77
20.23
40.91
97.03
92.56
79.21
Vacuum
Floated Filter
Scum Filtrate
13800
5300
11600 132
71
-------
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
16 MARCH 1973
Waste
Analysis to Pit
pH, units
BOD, mg/1
TOC, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to ph 3.7*
Turbidity, FTU
* mg/1 as CaC03
Waste
From
Pit
11.38
491
350
2740
810
743
365
213
423
720
475
Flotation
Effluent
11.02
207
162
1850
330
90
64
74
250
370
85
Flotation
Percent
Removal
57.84
53.71
32.48
59.26
87.88
82.47
65.26
D.E.
Effluent
10.95
139
124
1840
310
33
32
65
215
325
35
System
Percent
Removal
71.69
64.57
32.85
61.73
95.56
91.23
69.48
Vacuum
Floated Filter
Scum Filtrate
11900
4100
10400 40
34
-------
LO
O
(Ji
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
20 MARCH 1973
Waste
Analysis to Pit
pH, units
BOD, mg/1
TOG, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Turbidity, FTU
* mg/1 as CaC(>3
Waste
From
Pit
11.9
742
490
2379
1764
1082
444
347
850
1188
390
Flotation
Effluent
11.50
382
293
2450
1813
188
99
85
340
490
90
Flotation System
Percent D.E. Percent
Removal Effluent Removal
48.52
40.20
0
82.62
77.70
75.50
Vacuum
Floated Filter
Scum Filtrate
39263
14472
1163 40
28
-------
TABLE C-12-, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
21 MARCH 1973
Analysis
o
en
Waste Flotation
Waste From Flotation Percent
to Pit Pit Effluent Removal
System
D.E. Percent
Effluent Removal
Vacuum
Floated Filter
Scum Filtrate
pH, units
BOD, mg/1
TOC, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Turbidity, FTU
* mg/1 as CaCO-j
12,85 11.70
1670 214
1115 168
16995 3262
16357 2934
4438 107
1485 47
242 93
10360 435
11300 590
540 72
87.19
84.93
80.81 13642
82.06 9690
97.59 10388 21
96.84 17
61.57
-------
o
«J
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
22 MARCH 1973
Waste
Analysis to Pit
pH, units
BOD, mg/1
TOC, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Turbidity, FTU
* mg/1 as CaC03
Waste
From
Pit
11.70
588
425
4416
3646
1522
1085
331
750
1175
375
Flotation
Effluent
12.75
462
322
7951
7602
354
166
214
4820
5300
275
Flotation System
Percent D.E. Percent Floated
Removal Effluent Removal Scum
21.43
24.24
0 21827
0 21796
76.74 16288
84.70
35.35
Vacuum
Filter
Filtrate
24
20
-------
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
23 MARCH 1973
Analysis
pH, units
BOD, mg/1
w TOG, mg/1
0
oo
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Turbidity, FTU
Ca, mg/1
Si, mg/1
Waste
Waste From
to Pit Pit
11.35
778
528
5458
4114
1021
400
260
475
860
440
790
7
Flotation
Flotation
Effluent
11.55
333
246
4068
3394
101
66
126
315
460
90
420
7
Percent
Removal
57.20
53.41
25.47
17.50
90.11
83.50
51.54
46.84
0
D.E.
Effluent
11.55
199
149
3547
2930
15
12
87
310
440
33
330
6
System
Percent Floated
Removal Scum
74.42
71.78
35.01 19507
28.56 13522
98.53 14392
97.00
66.54
58.23
14.29
Vacuum
Filter
Filtrate
26
15
* mjs/1 CaC03
-------
TABLE C-12, CONTINUED
LABORATORY AMAT.YSES
FOR LINEN WASTEWATER TREATMENT
23 MARCH 1973
w
Raw Raw Flotation
Waste Waste Flotation Percent D.E.
Analysis to Pit From Pit Effluent Removal Effluent
Ca,
Mg,
Cu,
Pb,
Hg,
Cd,
Zn,
Cr,
Fe,
Ni,
Si,
mg/1
mg/1
mg/1
mg/1
lig/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
790 420
1.
0.
0.
-
0.
0.
0.
2.
2.
7
66
27
70
—
04
47
06
31
10
7
46.84 330
1.
0.
0.
-
0.
0.
0.
0.
0.
0 6
12
14
30
— '
02
06
03
15
15
System Vacuum
Percent Floated Filter
Removal Scum Filtrate
58.
32.
48.
57.
—
50.
87.
50.
93.
92.
14.
23
53
15
14
00
23
00
51
86
29
-------
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
28 MARCH 1973
Waste
Waste From
Analysis to Pit Pit
pH, units
BOD, mg/1
TOC, mg/1
w Total Solids, mg/1
° Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Turbidity, FTU
Ca, mg/1
Si, mg/1
9.83
425
320
6350
1260
780
336
193
190
A58
460
1430
51
Flotation System Vacuum
Flotation Percent D.E. Percent Floated Filter
Effluent Removal Effluent Removal Scum Filtrate
9.90
173
133
3560
375
40
31
29
115
220
42
690
65
10.05
59.29 161
58.44 124
43.94 3390
70.24 630
94.87 115
90.77 26
84.97 40
345
200
28
51.75 590
0 60
8.65
62.12 197
61.25 181
46.61 11200 2830
50.00 3870 630
85.26 7510 58
92.26 38
79.27 48
18
155
58.74
0
* mg/1 as CaCO.
-------
TABLE C-12, CONTINUED
LABORATORY ANALYSIS
FOR LINEN WASTEWATER TREATMENT
29 MARCH 1973
Waste
Analysis to Pit
pH, units
BOD, mg/1
TOC, mg/1
Total Solids, mg/1
Vol. Total Solids, mg/1
Suspended Solids, mg/1
Vol. Sus. Solids, mg/1
Grease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Turbidity, FTU
* mg/1 as CaC03
Waste
From
Pit
9.48
701
484
6700
1560
562
381
118
95
331
230
Flotation
Effluent
9.60
318
231
5960
950
131
88
21
83
180
52
Flotation
Percent
Removal
54.64
52.27
11.04
39.10
76.69
76.90
82.20
D.E.
Effluent
9.62
274
186
5860
890
97
70
24
80
173
46
System
Percent Floated
Removal Scum
60.91
61.57
12.54 6120
42.95 1070
82.74
81.63
79.66
Vacuum
Filter
Filtrate
-------
u>
TABLE C-12, CONTINUED
LABORATORY ANALYSTS
FOR LINEN WASTEWATI:R TREATMENT
19 APRIL 1973
Waste
Analvsls to PI t
pll, units
!50D, TOR /I
TOG, mg/1
Total Solids, mg/1
Volatile Total Solids, mg/1
Suspended Solids, mg/1
Volatile Suspended Solids, mg/1
Crease, mg/1
Alkalinity to pH 8.3*
Alkalinity to pH 3.7*
Turbidity FTU
Waste
From
Pit
9.9
732
610
6040
1660
2210
900
291
434
974
450
Flotation
Ef fluent
9.7
195
159
3570
689
100
63-
52
106
204
85
Flotation
Percent
Removal
73.36
73.93
40.89
58.49-
95.48
93.00
82.13
D.E.
Effluent
9.8
179
136
3550
660
39
25
30
100
190
40
Sys tern
Percent
Removal
75.55
77.70
41.23
60.24
98.24
97.22
89.69
Vacuum
Floated Filter
Scum Filtrate
47600
23900
41200 146
93
* mp/1 as C
-------
APPENDIX D
INCINERATION OF LAUNDRY WASTEWATER SLUDGE
313
-------
INCINERATION OF LAUNDRY SLUDGE
Reference 20 was utilized to develop an approximate operating cost for
incinerating laundry sludges, due to the high cost of sludge hauling in
Chicago. It was felt this mathematical model would provide adequate
results for feasibility determinations. Two cases were selected for the
computer program, the details of which are presented in Table D-l. The
sludge fuel values were assumed, as no data on actual heat values were
available. It is expected that the fuel value is quite high due to the
quantity of grease present. This compared to 2,000 to 2,250 kg-cal/kg
volatile solids (8,000 to 9,000 BTU/lb) for the combustible fraction of
municipal refuse. Fluid!zed bed incineration was selected as the most
suitable incineration technique for laundries, as it provides the most
efficient fuel utilization of available incineration processes.
The incinerator capacity was based on a filter yield of 1680 wet kgs/hr
(3700 wet Ibs/hr) at a 757 1pm (200 gpm) system flow of industrial laundry
wastewater containing 80% volatile solids, and 15% total solids. The
computer print out results are presented in Tables D-2 and D-3 for cases
1 and 2 respectively. It was assumed for the above costs that the
system operated for nine hours each day at 757 1pm (200 gpm). In both
instances, the operating costs are near 60c/cu m of wastewater ($2.50/
1000 gal.), thus causing almost a 40c/cu m ($1.50/1000 gal.) cost increase
in treatment. The capital outlay of $300,000 and the short incinerator
life produced excessive operating costs. Few laundries could afford
a several hundred thousand dollar expenditure in addition to a wastewater
treatment system. Thus, incineration was not economically feasible for
sludge handling.
If it is presumed that the heat from the incinerator were recovered and
used to heat effluent water from the heat exchanger from 130°F to 190°F,
and if it is assumed that the laundry has No. 2 fuel oil fired boilers
transferring heat at 75% efficiency, then $1.00 worth of fuel oil could
be saved for each 3.78 cu m (1000 gal.) of water heated; or 21c cu m
(80C/1000 gal.) waste treatment costs could be recovered. This allows
for 20% water loss. The net sludge handling cost is now about A5c/
cu m ($1.70/1000 gal.) wastewater treatment, still an excessive amount.
This figure does not include the costs of hauling the incinerator residue
either.
314
-------
TABLE D-l
MATHEMATICAL INCINERATION MODEL
TEST CASE CONDITIONS
Parameter Case 1 Case 2
Sludge Fuel Value - kg-cal/kp 2,192 2,520
volatile solids
Fuel Used No. 2 Fuel Oil No. 2 Fuel Oil
Fuel High Heat of Combustion, k*-cal/ 2,520 2,520
ke;
Feed Rate - wet kg/hr 1,680 1,680
Volatile Solids (VS) - % 80 80
Moisture Content - % 85 83
Fuel Cost - $/106 kg-cal 5.95 5.95
Fraction of year system used 0.27 0.27
Electric cost - $/kw hr 0.04 0.04
Maintenance labor - rate - $/hr 4 4
Service Labor rate - $/hr 8 8
Operating Labor - $/year 5,000 5,000
Ambient Air Temperature - °F 60 60
315
-------
TABLE D-2
CASE 1
ON SITE FLUIDIZED BED LAUNDRY SLUDGE INCINERATION COSTS
Item Cost - $/yr
Operating Labor 300
Fuel 11,750
Power 1,865
Total Operating Costs 13,953
Materials 367
Sand Make Up 85
Maintenance Service Labor 126
Maintenance Labor 1,179
Total Maintenance Costs 1,757
Equipment cost including reactor, Total Cost - $
controls, vet scurbber, pumps,
water clarification 260,683
Installation 26,068
Engineering fee 28,675
Total Capital outlay 315,426
Yearly Amortization Costs @ 6% interest
and 7 year life 56,461
TOTAL Operating Cost - 68c/cu m raw
wastewater
316
-------
TABLE D-3
CASE 2
ON SITE FLUIDIZED BED LAUNDRY SLUDGE INCINERATION
Item Cost - $/yr
Labor
Fuel
Power
Total Operating Costs
Materials
Sand Make Up
Maintenance Service Labor
Maintenance Labor
Maintenance Costs
Equipment Costs including reactor Total Cost - $
controls, wet scrubber, pumps,
water clarification 277,728
Installation 27,773
Engineering Fee 30,550
Total Capital Outlay 366,051
Yearly Amortization Cost @ 6% interest,
and 7 year life 65,523
TOTAL Operating Cost equals 67c/cu m raw
wastewater
317
-------
The size of the incineration system also mitigated against its usage.
The size of both incinerators of Tables D-2 and D-3 was 7.3 m (24 ft)
high by 6.1 m (20 ft) by 9.1 m (30 ft). Additional area is required for
a water clarification system for the wet scrubber cleaning the exhaust
gases. Thus, laundry personnel now must also becone involved in air
pollution control and the operation of a complex air pollution control
system.
Therefore, incineration is rejected for usage at the Roscoe laundry due
to excessive space requirements and capital investment. For large
industrial laundries able to dewater sludge to a high solids content,
incineration may be a feasible process. Work is needed in developing
more accurate cost figures for actual sludge fuel values and moisture
contents, as well as for a wide variety of conditions in order to more
firmly establish incineration costs for actual field conditions and to
establish at what point incineration may be economically feasible. This
could be easily done by running the same computer program at a variety of
variable levels.
318
-------
APPENDIX E
DEMONSTRATION SYSTEM COSTS
319
-------
The following is a breakdown of the equipment and construction costs incurred
for the completion of the demonstration facility.
Diatomaceous Earth Filter System
Body Feed Pump $ 642
Valves 600
DE Slurry Mixer 614
Slurry Mix Tank 200
Precoat Pump 519
Air'Release Valve 143
DE Filter 4.500
$ 7,218
Vacuum Filtration System
Vacuum Filter $14,550
Vacuum Pump 2,011
Sludge Conditioning Pump 888
Filtrate Water Totalizing Meter 383
Sludge Cake Pump 1,833
Sludge Conditioning Tank 599
Sludge Conditioning Tank Mixer 294
Sludge Level Control System 300
Filtrate Receiver 450
Conditioning Chemical Mixer 248
Filtrate Pump 699
Valves 300
$22,555
320
-------
Flotation System
Flocculator Tank $ 800
Flotation System including chemical feed pumps, 23,269
flow meters, valves, pressurized flow system, pumps,
and tankage and all control panels
$24,069
Miscellaneous
Sludge Tank Enclosure $ 758
Concrete and Sewer Work 1,383
Plumbing Work 10,003
Electrical Work 4,932
Mechanical Erection 3,180
Ladders and catwalks 200
$20,456
TOTAL $74,298
321
-------
APPENDIX F
DIAPER LAUNDRY WASTEWATER TREATMENT
322
-------
DIAPER LAUNDRY WASTEWATER TREATMENT
CONCLUSIONS
1. Diaper laundry wastewater is similar in strength and appearance to
linen laundry wastewater.
2. Approximately 2.5 kgs of TOC/100 kgs of diapers laundered is generated
in the laundering process. Eight to nine kilograms of total solids/
100 kgs of diapers washed are generated. The suspended solids
generated from the washing process were about 1.4 kgs/100 kgs of
diapers laundered.
3. Alum and sulfuric acid provided effective chemical treatment for old
diaper laundry wastewater in this study.
4. Bench scale flotation was an effective solids separation step for the
diaper laundry wastewater.
5. Disinfection of diaper laundry wastewater would be required if the
water was going to be reused.
6. Diaper laundries will be forced to treat their wastewater, as other
laundry types, due to hexane soluble and pH limitations.
RECOMMENDATIONS
1. Perform pilot plant wastewater treatment studies to firmly establish
the characteristics of diaper laundry wastewater and its treatment
as well as associated costs.
2. Obtain more extensive information on the size of diaper laundries and
variation in diaper laundry wastewater characteristics in order to
define the extent of the water pollution control problem and the
degree of applicability of any waste treatment system.
3. Develop a diaper laundry wastewater treatment flow sheet.
323
-------
4. Obtain information on the type and variability of supplies utilized
by the diaper laundry industry and the effect each could have on
wastewater treatment.
5. Develop water reuse feasibility information
INTRODUCTION
The laundry wastewater treatment project described in the main part of
this report was funded in part by the National Institute of Infant
Service, which represents the diaper laundry industry. During the course
of the project, it was hoped that diaper laundry wastewater could be
treated by the demonstration system. Unfortunately, this was not
possible. However, during the course of the project, data about their
water pollution problems was obtained from diaper laundry wastewater
bench scale treatment and from an industrial survey of diaper laundry
water usage. This information is presented in this Appendix to provide
some insight into the diaper laundry water pollution control problem.
DIAPER LAUNDRY WASTEWATER QUALITY
On December 17, 1971, a diaper laundry in the Milwaukee area was visited
for the purpose of characterizing diaper laundry wastewater. The
laundry visited has an average flow of 75,700 Ipd (20,000 gpd).
Approximately 1636 kg (3600 Ibs) of diapers are washed in a day in two
washer-extractors which includes 409 kgs (900 Ibs) of rewashed diapers.
Thus, about 46 liters of water per kilogram of diapers (5.5 gal./lb)
are utilized.
Grab samples were obtained from each machine dump for four different
loads of diapers. Samples of each machine dump were composited to obtain
a representative sample of wastewater for bench scale treatment tests.
The samples were composited in 500 and 1000 ml fractions depending on
whether the machines were at a high or low level of water. All grab
samples were analyzed for total solids, to'tal organic carbon (TOC), and pH.
The composites made were subjected to rigorous chemical analysis. The
volume of water utilized in each washing cycle was obtained from the
plant water meter. When both washers were demanding water, it was not
possible to obtain a volume. The figures that were obtained were very
erratic even though the machines operated at only two levels. The first
flush demanded much more water than the second flush, as the diapers were
initially dry. After an extraction, a considerable amount of water was
also demanded. These variations made it difficult to determine water
volumes for washing cycles where volume was not measured. Those cycles
that did not have a measurable water flow were estimated from the data
obtained.
The results from the wastewater analysis of the individual machine dumps
are reported in Tables F-l through F-4. To the first suds is added
2.7 kgs (6 Ibs) to 4.5 kgs (10 Ibs) of detergent, 227 to 340 gms (3-12 oz) of
324
-------
TABLfi F-l
VARIATION OF WASTEWATER QUALITY WITH WASHING
OPERATION FOR 182 KGS OF DIAPERS (LOAD 1)
Operation
Flush
Flush
Extract
Suds
Suds
Suds
Carryover
Bleach
Rinse
Rinse
Rinse
Extract
Rinse
Blueing
Sour and Soften
Extract
Total Solids
(rag/I)
1513
1444
1350
4265
4597
4115
3207
3210
1731
1206
1085
1174
463
505
552
525
TOC
(mg/.l)
535
468
428
1382
1233
980
830
786
376
265
188
205
51
88
87
72
PH
(units)
9.05
9.1
9.1
11.9
12.0
11.85
11.65
11.45
10.9
10.55
10.2
10.4
9.2
9.35
6.3
6.75
325
-------
TABLE F-2
VARIATION OF WASTEWATER QUALITY WITH WASHING
OPERATION FOR 182 KGS OF DIAPERS (LOAD 2)
Water Utilized TOC Total Solids
Operation (liters) (mg/1) (tng/ll
Flush —
Flush
Extract
Suds —
Suds
Suds
Carryover 231
Bleach
Rinse 269
Rinse 674
Rinse 572
Extract —
Rinse 1241
Blueing 541
Sour & Soften 223
Extract —
410
405
360
1438
1553
1144
851
763
309
460
215
210
75
98
88
55
1363
1329
1258
4527
5279
5028
3551
3835
2375
1541
1195
1268
412
466
560
429
Suspended
Solids pH
(mg/1) (Units)
164
167
39
766
712
828
608
572
353
248
214
128
103
125
117
29
9.1
9.1
9.1
12.15
12.25
12.10
11.9
11.8
11.35
10.65
10.65
10.7
9.65
9.7
6.75
7.0
326
-------
TABLE F-3
VARIATION OF WASTEWATER QUALITY WITH WASHING OPERATION FOR
273 KGS OF DIAPERS (LOAD 1)
Operation
Flush
Flush
Suds
Suds
Suds
Carryover
Bleach
Rinse
Rinse
Rinse
Rinse
Blueing
Sour and
Total Solids
(mg/D
1514
1299
4152
4859
3878
3152
3104
2093
1559
1216
467
519
Soften 507
TOC
Qng/D
423
345
1208
1364
988
498
694
418
330
218
82
94
58
pH
(Units)
8.9
8.95
11.8
11.95
11.85
11.75
11.6
11.25
10.9
10.6
9.65
9.55
6.70
Water
Utilized
(liters)
526
625
746
700
568
327
-------
TABLE F-4
VARIATION OF WASTEWATER QUALITY WITH WASHING OPERATION
273 KGS OF DIAPERS (LOAD 2)
Operation
Flush
Flush
Suds
Suds
Suds
Carryover*
Bleach
Rinse
Rinse
Rinse
Rinse
Blueing
Sour and Soften
Total Solids
(mg/1)
1704
1293
5172
4890
4477
2580
3220
2155
1635
1225
599
538
567
TOC
(mg/D
490
375
1535
1495
1245
678
749
361
340
248
100
—
__
pH
(mg/1)
8.9
8.95
12.05
12.10
12.0
10.3
11.6
11.2
10.85
10.65
9.7
9.6
6.5
Water
Utilized
(liters)
1877
693
2394
469
643
1646
560
* Bad sample.
328
-------
bleach to the bleach cycle, 30 to 50 drops of blueing to the blueing
cycle, and a sour, 227 gms (8 ounces) of antiseptic and fabric softener
in the final cycle. After the addition of the detergent a large
increase in pH, total solids, and TOG can be observed. The addition of
blueing causes a slight increase in total solids and TOG. Addition of the
rest of the supplies in the final cycle reflects a slight increase in
total solids and a final pH between 6.0 and 7.0. Bleach addition also
yielded a slight increase in total solids. Soap regenerator did not.
In general, the wastewater contaminant concentrations tend to decrease
with each succeeding cycle after the first suds.
The detergent used is an alkaline silicate, and the soap regenerator is a
sodium metasilicate compound. The antiseptic utilized was a dimethyl
benzyl ammonium chloride compound containing 8.5% alcohol. The soxir was
sodium bifluoride. The chemical characteristics of the blueing and
fabric softener were not obtained.
All four wash loads sampled yielded about the same results indicating a
fairly consistent type of wastewater emanating from the diapers. Based
on this data, large variations in wastewater coming from the washing
machine would not be expected. However, an equalization tank of some
sort would be required due to the intermittence of the flow and to the
relatively wide variation in wastewater quality between wash operations.
In this respect, a diaper laundry is similar to all others, in that
equalization is required to hold one to two hours of plant flow.
Table F-5 presents the amounts of TOG and total solids generated per 100
kgs of diapers washed. Total solids figures are reported including and
not including the supplies. The calculations for this table were based
on the measured water volumes for each operation. Those operations that
had no direct water measurements were estimated from the other measure-
ments obtained. It is felt these estimates are reasonable. Table F-5
demonstrates that between 5.5 and 6.2 kgs of wastewater total solids are
generated by 100 kgs of diapers. The supplies added another 2.5 to
3.0 kgs of solids per 100 kgs of diapers. The amount of TOG generated
by the laundering process was between 2.2 and 2.6 kgs TOG per 100 kgs
of diapers laundered. The suspended solids generated amounted to only
1.4 kgs/100 kgs of diapers. This was measured for only one load. The
amount of TOG generated was comparable to that obtained from synthetic
shirts, pants, and kitchen towels, as are the total solids generated by
the diapers with the supplies included. Thus, diaper laundry wastewater
is comparable to uniform or heavy soil linen wastewater. Indeed, diaper
wastes are quite similar to linen laundry wastes in appearance. A strong
ammonia odor is the most readily apparent difference.
BENCH SCALE TREATMENT TESTING
Due to the difficulty in determining the exact water volumes used each
wash operation, the composites that were made may not be entirely
representative of a diaper laundry wastewater in view of the assumptions
made. Consequently the analyses presented for the two composite samples
329
-------
TABLE F-5
ESTIMATED WASTE LOADS FROM DIAPER LAUNDERING
kgs Total Solids per kgs Suspended
kgs TOC per 100 100 kgs Diapers Laundered Solids per 100 kgs
Sequence Ibs Articles Laundered w/supplies y7o supplies Diapers Laundered
273 kg-#l 2.16 8.08 4.17
273 kg-#2 2.55 9.16 6.24
§ 182 kg-#l 2.30 7.90 5.50 1.39
-------
should not be taken as absolute values, but are subject to a great deal
of variation due to sampling technique and differences betx^een laundries
as noted in the main report.
The two composite samples obtained were analyzed and subjected to bench
scale chemical treatment and flotation tests. Analyses of the two
composites appear in Table F-6. From this table, it can be seen that the
BOD is slightly higher and the suspended solids of the composite samples
about the same as that of raw sewage. Therefore very little surcharge
impositions would be expected at this particular laundry based on
these samples. Grease content and composite pH may be a problem in some
municipalities dependent on their sewer discharge ordinances. Some
communities may allow a discharge of water with a pH of 10.5, others only
a pH of 9.0. This problem is regional in nature. The grease content
is sufficiently high to conflict with almost all sewer ordinances, as they
usually allow only between 50 and 150 mg/1 of grease to be discharged.
Thus, in some instances, neutralization and a solids separation step may
be required for diaper laundry waste treatment. If the water were to be
reused, disinfection would be required due to the presence of viable
coliform organisms. Most of these organisms probably came from the
flushing operations where no detergent and relatively cool water are
utilized. The carryover of subsequent disinfectants and hot water is
apparently not enough to kill them all. Approximately 3 x 10" coliforms/
ml were measured in the first flush. It would be expected that the
flushes could be bypassed if wastewater reuse were to be attempted.
Chemical treatment tests performed on the composites showed that alum
(A12(SO^)3'18H20) by itself or anionic and nonionic polyelectrolytes by
themselves did not properly treat the waste. Ferric chloride and calcium
chloride were able to form floe particles, but alum in conjunction with
sulfuric acid provided the most effective chemical treatment.
Neutralization of the wastewater to a pH of 8,5 followed by flocculation
of the waste for two minutes after addition of 700 mg alum/1 and 1 mg/1
of a nonionic polyelectrolyte to strengthen floe provided good chemical
treatment.
The samples obtained were not tested -until ten days after they arrived
in the laboratory. Consequently, the age of the samples may have
affected the -chemical treatment characteristics of the waste, as it did
for linen wastewater. Calcium chloride may have proved to be the most
effective coagulant had the samples been tested fresh. The presence of
a large amount of silica and the similarity of the diaper wastewater
to linen wastewater suggests that this is the case.
Nonetheless, four bench scale flotation tests were performed utilizing
the alum-acid treatment, the results of which are presented in Table F-7.
This table demonstrates that good effluent quality was obtained.
Approximately 75% of the TOC was removed and 80-90% of the suspended
solids. Effluent clarity was almost that of tap water. With proper
disinfection, it probably could be reused within the laundry without
331
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TABLE F-6
WASTEWATER CHARACTERISTICS OF DIAPER
LAUNDRY COMPOSITES OF 12/17/71
Analysis
Total Solids - ntg/1
Total Volatile Solids - mg/1
% Total Volatile Solids
Suspended Solids - mg/1
Z Suspended Volatile Solids
TOC - mg/1
Soluble TOC - mg/1
BOD - mg/1
Total Phosphorus as P - mg/1
pH - units
Grease - mg/1
Alkalinity - mg/1 as CaC03
Mercury - ug/1
Lead - mg/1
Silica - mg/1 as Si02
Ammonia Nitrogen - mg/1 as N
Kjeldahl Nitrogen - mg/1 as N
Iron - mg/1
Total Coliform/100 ml
400 Ib Composite
1667
668
40
290
100
363
171
462
32
10.3
306
690
<1
0
255
41
129
0.3
490,000
600 Ib Composite
1803
812
45
279
100
443
222
664
28
10.5
349
825
<1
0
270
41
129
0.4
2,200
332
-------
RESULTS OF BENCH SCALE FLOTATION TEST FOR
DIAPER LAUNDRY COMPOSITES OF 12/17/71
Sample
Test No.
l^SO^ Dosage, mg/1
Alum Dosage, mg/1
Nonionic polyelectrolyte
dosage, mg/1
pH after H2S04 Addition
Recycle Rate , %
Rise Rate, mpm
Detention Time, min.
Scum Volume, 1/1000 1
Settled Solids, 1/1000 1
Effluent Suspended Solids,
mg/1
Effluent Total Solids, mg/1
Effluent TOC, mg/1
Effluent pH
% Suspended Solids Removal
% TOC Removal
400 comp 400 comp 600 comp 600 comp
1
294
700
1
8.6
33
0.12
8
80
0
27
1450
82
6.1
91
77
2
294
700
0
8.6
33
0.21
8
80
0
56
1482
95
6.1
81
74
3
327
700
1
8.75
33
0.43
8
80
0
70
1606
109
6.3
75
75
4
370
700
1
8.45
33
0.4^
8
80
0
19
1556
82
6.2
93
81
333
-------
banning the diapers. Without the use of a polyelectrolyte, effluent
clarity and suspended solids are impaired, as shown by comparing Tests 1
and 2. Fairly high rise rates were observed in three of the tests,
indicating a flotation unit would not have to be overly large.
Thirty-three percent recycle proved adequate, and waste treatment produced
80 liters of scum per 1000 liters of wastewater. Noting the cos.t of
hauling liquids, it would be desirable to reduce this volume. However,
the comments presented in the main report regarding alum sludge dewatering
are equally true for this wastewater. In regard to the treatment concept,
it is beneficial to consider attempting to utilize calcium chloride
for chemical treatment in order to produce a scum that is readily
dewaterable, if costs are to be kept reasonable and sludge handling is not
to become a problem. In general, the waste treatment scheme required for
diaper laundries should not have to be much different from that of linen
laundries. Work is required in trying to adapt the treatment
process outlined for linen laundries to the diaper industry, because the
wastewater characteristics are different, and the wastewater will require
treatment due to the hexane soluble and pH levels. Heavy metals were not
a problem.
INDUSTRY WASTEWATER SURVEY
Table F-8 summarizes the results of 20 usable diaper laundry industry
survey forms that were sent to the Envirex office for analysis to
obtain information on diaper laundry water costs, consumption, and sewer
expenditures (see Appendix A). Due to the relatively small number of
laundries reporting, the figures presented cannot be taken as absolute.
However, the water and sewer costs reported are about the same as for
other laundries, which would be expected. Only one laundry reported a
sewer surcharge, and it was very low. Looking at the wastewater analyses
reported for BOD and suspended solids and noting the results obtained
from the composite samples obtained, it appears that diaper wastes are
of lower strength than linen laundries, and consequently, sewer surcharges
do not appear to be a problem for diaper laundries.
Table F-8 demonstrates a large variation in diaper laundry size and water
consumption. It is evident that diaper laundries come in a wide variety
of sizes with an average water usage of 204 cu m per day (54,000 gpd).
This is generally lower than other laundry types. The data also indicated
a larger amount of water consumed per kg of diapers laundered than for
other laundry types. This could well be attributed to the small amount
of data. Washroom costs tended to be lower for diaper laundries, and
would be expected to some degree since there was no sewer surcharge
indicated. In general, the cost and consumption of water by diaper
laundries is not greatly different from that of linen and industrial
laundries.
A good relationship between laundry size and water consumption was
obtained, as demonstrated in Figure F-l. The correlation of the two
variables was an excellent one. A least squares regression line is
334
-------
TABLE F-8
AVERAGE WATER USAGE AND WATER COSTS
FOR 20 DIAPER LAUNDRIES
Item
Range
Raw Water Cost
(C/cu m
Sewer Charge
m)
Sewer Surcharge
(C/cu m)
Water Consumption
(1000 Ipd)
Liters Water Consumed/
kg diapers washed
1000 kgs diapers washed/wk
Total Laundry Size
(1000 kg /week
Total Washroom Costs
(C/cu m)
Washroom Costs
(C/100 kgs laundered)
Wastewater BOD - (mg/1)
Wastewater Suspended
Solids (mg/1)
3.4-12.4
0-7.4
42-662
28.3-57.5
1.2-75
6.8-93
5.5-19.6
24-81
200-486
120-553
Average
6.9
4.0
0.8
204
45.8
16.4
25
10.6
51
342
372
No. of
Responses
18
10
1
16
11
19
18
10
8
2
335
-------
g
757
g
o 37'8
o
o
265
a
I
i
'. :
0
i j
gg
189
37.8
/
JL.
4.5
9.0 13.6 18.0 27.3 36 45 91
Diaper Laundry Size - 1000 kgs/week
182
FIGURE F-l
DIAPER LAUNDRY WASH LOAD VS. WATER CONSUMPTION
-------
drawn on the curve with a correlation coefficient of 0.97 calculated for
this line. The slope of this line is 43.3 liters of water/kg of diapers
(5.2 gal/lb) laundered. No correlations were demonstrated between water
consumption and cost or water consumed per unit weight washed and laundry
size. A summary of the 20 responses obtained is presented in Table F-9.
DIAPER LAUNDRY WASTEWATER TREATMENT REQUIREMENTS
From the foregoing and the general results obtained from all laundry
studies, it is evident that wastewater treatment is going to be needed by
many diaper laundries. It is feasible based on the bench test results of
this study and on the results of the linen laundry wastewater testing.
Consequently, diaper laundries have to be prepared to install treatment
systems and incur operating costs comparable to that of linen laundries,
e.g. 20c to 40c/cu m of wastewater treatment (75c to 150e/1000 gal.).
The wastewater treatment system installed will have to be capable of
reducing hexane solubles below 100 mg/1 as well as significantly reducing
suspended solids. In certain instances, flotation will provide the
necessary degree of treatment while other instances will require diato-
maceous earth filtration. Diatomaceous earth filtration should be a
viable process for the diaper laundry industry considering the low
suspended solids concentration of the wastewater.
Information is needed for diaper laundry wastewater treatment on a pilot
plant basis to conclusively determine what coagulants can be utilized,
the dewaterinp characteristics of diaper scum, the allowable flotation
tank hydraulic loadings, and .operating and capital costs for wastewater
treatment. As it stands, only rudimentary conclusions regarding treatment
characteristics and costs can be drawn. There is enough difference
between diaper laundry and linen laundry wastewater bacteriologically and
in nutrient content, as demonstrated in Table F-6 (note high phosphorus
and nitrogen contents), that significant differences in wastewater
treatability on a continuous basis could manifest themselves. It is a
demonstrated fact that phosphorus can interfere with the coagulation
process as pointed out by Stumrn and O'Melia (1). Therefore, it is
strongly urged that work be undertaken in the area of pilot plant treatment
to establish diaper laundry wastewater treatment system design parameters.
This will show to what degree diaper laundry wastewater ma}' be likened to
linen wastes. The degree of applicability of wastewater treatment could
not be determined by this cursory study.
337
-------
TABLE F-9
DIAPER INDUSTRIAL SURVEY RESPONSES REGARDING WATER CONSUMPTION AND COST
No.
1
2
3
4
5
6
7
w 8
g 9
10
11
12
13
14
15
16
17
18
19
20
Raw Water
Cost
(C/cu m)
6.9
5.0
12.4
10.0
4.0
11.4
7.1
10.0
5.0
6.9
7.7
5.5
3.4
5.8
5.3
5.3
—
7.1
— —
7.7
Sewer
Sewer Charge Surcharge
m) (C/cu m)
Size liters Water Water Total Wash-
(1000 kgs diapers Consumed/ Consumption Room Costs
Laundered/week) kg laundered (1000 Ipd) (C/cu m)
7.1
4.5
7.4
5.3
4.5
3.7
1.8
2.1
4.0
0
0
0
0.8
0
0
0
0
0
•»••
••<*
0
0
3.9
17.7
37.3
1.2
6.8
20.5
4.9
6.6
7.3
7.2
19.5
15.9
4.5
10.0
38.2
75.9
36.4
8.9
25.3
_
57.5
54.1
—
56.6
42.5
—
45.0
28.3
--
36.7
53.3
—
40.8
38.3
—
—
—
46.6
238
204
405
153
102
174
167
61
42
—
144
180
116
81
291
—
662
— .
235
_
12.2
—
—
8.5
19.6
12.4
14.5
8.7
8.7
..*-
55
—
9.2
—
7.1
—
__
-------
REFERENCES
1. Stunm, W. and O'Melia, C. R. Stoichioraetry of Coagulation,
Journal American Water Workds Assoc. 60:568 (1968).
339
-------
APPENDIX G
ENGLISH-METRIC CONVERSION TABLE
340
-------
To Convert
BTU
cfm
cm
cm
cu cm (ml)
cu ft
cu ft
cu m
cu m
cu m
cu m/min
cu yd
ft
ft
gal.
gal.
gm
gm/cu cm
gpm
gpm/sq ft
in.
kg
kg-cal
TO
kg-cal
cu m/min
in.
ft
cu ft
cu m
cu cm
cu ft
gal.
cu yd
cfm
cu m
m
cm
1
cu m
Ib
Ib/cu ft
1pm
Ipm/sq m
cm
Ib
BTU
Multiply By
3.968
0.0283
0.394
0.0394
0.0000353
0.0283
28,320
35.31
264
1.31
35.31
0.765
0.305
25.4
3.785
0.003785
0.0022
62.4
3.785
40.7
2.54
2.20
0.252
341
-------
To Convert
kg/day/sq m
kg/sq on
kg/sq m
kg/sq m/hr
1
Ib
Ib
Ib/cu ft
Ib/day/sq ft
Ib/sq ft
Ib/sq ft/hr
1pm
Ipo/sq m
a
metric ton (1000 kg)
psi
sq ft
sq m
ton (short)
to
Ib/day/sq ft
psi
Ib/sq ft
Ib/sq ft/hr
gal.
kg
gm
gm/cu cm
kg/day/sq m
kg/sq m
kg/sq m/hr
gpm
gpm/sq ft
ft
ton (short)
kg/sq cm
sq m
sq ft
metric ton (1000 kg)
Multiply By
0.205
14.3
0.205
0.205
0.264
0.454
454
0.016
4.88
4.88
4.88
0.264
0.245
3.28
1.10
0.0703
I
0.0929
10.76
0.907
342
-------
SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
1. Report No.
2.
4. Title Modular Wastewatcr Treatment System Demonstration
For The Textile Maintenance Industry
7. Author(s)
Douglas, Gary
9. Organization
Linen Supply Association of America - Miami Beach,
Florida; Institute of Industrial Launderer's -
Washington, D.C. under contract to Envirex Inc.
J. Accession No.
w
J. Report Date Aug. 19, 1973
6.
£. Performing Organization
Report No.
10. Project No.
12. Sponsoring Organization
15. Supplementary Notes
Environmental Protection Agency
11. Contract/Grant No.
FYV 12120
13. Type of Report and
Period Covered Final
3/1/71 - 5/1/73
Environmental Protection Agency report number,
EPA-660/2-73-037, January 1974.
16. Abstract
An industrial waste survey of the textile maintenance industry was performed to
characterize and quantify the pollutants emanating from various types of plants.
Bench scale waste treatment tests were performed to design a system for the textile
maintenance industry.
A wastewater treatment system consisting of chemical treatment and flocculation
facilities, dissolved-air flotation for solids-liquid separation, diatomaceous earth
filtration for polishing the flotation effluent, and vacuum filtration dewatering of
flotation scum was installed at a commercial laundry.
Data was obtained on effluent quality, sludge volume, chemical costs and other
operating costs for industrial laundry wastewater, linen laundry wastewater, and
uniform laundry wastewater. The final effluent of the linen and uniform laundry
wastewater treatment met municipal sewer ordinance requirements for grease and heavy
metals. Wastewater suspended solids and BOD were also significantly reduced, so that
ilgh municipal sewer surcharges would not be imposed. The effluent from the industrial
laundry wastewater treatment did not consistently meet municipal sewer ordinance
standards.
Complete wastewater treatment operating costs were on the order of $0.80/cu m for
Industrial laundry wastewater, $0.66/cu m for uniform laundry wastewater and $0.40/cu m
for linen laundry wastewater. It was concluded that the treatment system had applic-
wastewater.
Coagulation, diatomaceous earth filtration, dissolved air flotation,industrial laundry
#ater costs, surcharges, .solids-liquid separation, vacuum filtration, biochemical oxygen }
demand,suspended solids.
17b. Identifiers
Chemical treatment; linen, uniform and industrial laundry
ordinances.
effluent? municipal sewer
17c. COWRR Field * Group
18. Availability
19. Security Class.
(Report)
20. Security Class.
(Page)
21. No. of
Pages
22. Price
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON. D. C. 20240
Abstractor Gary Douglas
Ittstitution
Inc.
WRSIC 102 (REV. JUNE 1971)
GPO 913.2ft
•U.S. GOVERNMENT PRINTING OFFICE:1974 546-316/245 1-3
------- |