v>EPA
United States
Environmental Protection
Agency
Municipal Environmental Research EPA-600/2-79-160
Laboratory December 1979
Cincinnati OH 45268
Research and Development
Development of
Methods and
Techniques for Final
Treatment of
Combined
Municipal and
Textile Wastewater
Including Sludge
Utilization and
Disposal
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development. U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6- Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental 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.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-79-160
December 1979
DEVELOPMENT OF METHODS AND TECHNIQUES FOR
FINAL TREATMENT OF COMBINED MUNICIPAL AND TEXTILE
WASTEWATER INCLUDING SLUDGE UTILIZATION AND DISPOSAL
by
Jan Suschka
Environmental Pollution Abatement Center
Department of Water and Wastewater Technology
Research Institute of Environment Development
Katowice, Poland
Grant No. PR5-532-2
Project Officer
Robert L. Bunch
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the views and
policies of the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or recommendation
for use.
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solu-
tion, and it involves defining the problem, measuring its impact, and
searching for solutions. The Municipal Environmental Research Laboratory
develops new and improved technology and systems for the prevention, treat-
ment, and management of wastewater and solid and hazardous waste pollutant
discharges from municipal and community sources, for the preservation and
treatment of public drinking water supplies, and to minimize the adverse
economic, social, health, and aesthetic effects of pollution. This publica-
tion is one of the products of that research; a most vital communications
link between the researcher and the user community.
This study was concerned with evaluating various combinations of waste-
water treatment processes for their effectiveness to treat a combination of
domestic and textile wastes. Special emphasis was placed on color elimina-
tion. The investigations were carried out on laboratory scale, employing
various mixtures of dyeing and municipal wastewaters.
Francis T. Mayo
Director, Municipal Environmental
Research Laboratory
111
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ABSTRACT
The report contains the results of studies and technological investi-
gations, which were aimed at the estimation of the usability of unit methods
of wastewater treatment, and sludge processing for the treatment of textile
wastewater, and towards choosing treatment technologies of these wastewaters.
In addition to the usability studies, the evaluation of identification
methods of dyeing wastewater components was done. The investigations were
carried out on laboratory scale. Technological studies included the following
methods: coagulation, ozonization, chlorination, bromination, adsorption,
activated sludge, anaerobic digestion of wastewater and sludge.
Based on the investigations, it can be stated that the dyeing wastewater
can be effectively treated using aerobic and anaerobic processes of wastewater
biological treatment. Wastewater cleaned biologically, particularly in
aerobic processes, however, are characterized in general by high color.
Physical and chemical methods remove color from dyeing wastewater, and give
a satisfactory organic substances removal.
The work has been accomplished within the Polish American agreement
Project PL-480, Grant PR5-532-2 by the Institute of Environmental Development,
Environmental Pollution Abatement Centre at Katowice, Poland, for the U.S.
Environmental Protection Agency.
The work was finished in October 1976.
IV
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CONTENTS
Foreword
Abstract ....... iv
Figures V1
Tables . . . xi
Acknowledgments xii
1. Introduction 1
2. Conclusions 2
3. Recommendations 3
4. Characteristics of Substrates Used for the Investigations . 4
5. Physical and Chemical Treatment Methods of Dyeing Waste-
waters 11
5.1 Coagulation 11
5.2 Ozonization 32
5.3 Chlorination 45
5.4 Bromination 58
5.5 Adsorption 65
6. Biological Methods for Dyeing Wastewater Treatment .... 79
6.1 The Activated Sludge Method 79
6.2 The Anaerobic Digestion of Wastewater 96
7. The Influence of the Selected Contaminants on the Anaerobic
Digestion of Sludge 117
References 133
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FIGURES
Number
Page
1 Effect of dyeing wastewaters coagulation with the use of
various doses of CaO as the coagulant !5
2 Color removal by coagulation method 0.1% dyeing wastewaters ... 16
3 Color removal by coagulation method 0.5% dyeing wastewaters ... 18
4 Color removal by coagulation method 3% dyeing wastewaters .... 20
5 Turbidity removal by coagulation method 0.1% dyeing wastewaters . 22
6 Turbidity removal by coagulation method 0.5% dyeing wastewaters . 23
7 Turbidity removal by coagulation method 3% dyeing wastewaters . . 24
8 Color removal by coagulation method effect of pH adjustment ... 25
9 Effects of 0.5% dyeing wastewaters treatment process by C07
saturation and coagulation using various CaO doses ....... 26
10 Effects of 0.5% dyeing wastewaters treatment process by coagu-
lation using various CaO doses and by C02 saturation 27
11 Effects of 0.5% dyeing wastewaters treatment process by CaO
coagulation and C02 saturation simultaneously used 28
12 Color removal by coagulation method 0.5% dyeing wastewaters ... 29
13 Efficiency of the coagulation process performed by the multiple
reuse of lime. Dose of CaO to 6.0 g/dm3 0.1% dyeing wastewaters . 33
14 Testing equipment for ozonation wastewaters process 34
15 Relationship between color removal and ozonation time in dyeing
wastewaters ozonation process 35
16 Color removal by ozonation effect of ozone consumed 36
17 Color removal by ozonation of different tested materials .... 37
IS Color removal by ozonation
VI
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Number Page
19 Relationship between color removal and ozone consumed in 0.005%
dyes solutions ozonation process 40
20 Spectra of the reactive dye water solution 42
21 IR-spectra of the reactive dye water solution 43
22 Removal of color by ozonation - effect of pH variations 0.1%
dyeing wastewaters 44
23 Testing equipment for chlorine water production 46
24 Relationship between color removal and chlorination time in 0.1%
dyeing wastewaters chlorination process using lime chlorinated
solution as an oxidizer 47
25 Relationship between color removal and chlorine consumed in 0.1%
dyeing wastewaters chlorination process - using lime chlorinated
solution as an oxidizer 48
26 Relationship between color removal and chlorine consumed in dyeing
wastewaters chlorination process using chlorine water as an
oxidizer 50
27 Color removal by chlorination of 0.1% dyeing wastewaters -
effect of UV light as catalyst 51
28 Color removal in 0.1% dyeing wastewaters treatment process by
coagulation, neutralization and chlorination 54
29 Spectra of 0.1% dyeing wastewaters after 15 minutes of chlorin-
ation applying 56
30 Spectra of 0.1% dyeing wastewaters 57
31 Spectra of 0.5% dyeing wastewaters 59
32 IR-spectra of 0.5% dyeing wastewaters 60
33 Relationship between color removal and bromination time in dyeing
wastewaters bromination process 62
34 Relationship between color removal and bromine consumed in dyeing
wastewaters bromination process 63
35 Spectra of 0.5% dyeing wastewaters 66
36 Spectra of dyeing wastewaters 67
VI1
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Number
37 Equilibrium adsorption capacity of cws powdered activated carbon
and nobel bentonite estimated for tested dyeing baths ...... 69
38 Equilibrium adsorption capacity of cws powdered activated carbon
and nobel bentonite estimated for tested dyeing baths and their
mixture ............................. 70
39 Color removal by powdered activated carbon adsorption effect of
pH adjustment to 12 ....................... 73
40 Adsorption isotherm on powdered activated carbon - carbopol ws
for 0.5% dyeing wastewaters without pH adjustment ........ 76
41 Color removal by powdered activated carbon adsorption 3% dyeing
wastewaters effect of varying activated carbon doses ...... 78
42 Frequency of BODr unfiltered. Series I ............. 82
43 Frequency of influent COD and effluent COD. Series I ...... 83
44 Frequency of influent, effluent BOD . Series II ........ 84
45 Frequency of influent, effluent COD. Series II ......... 85
46 Correlation between organic load of activated sludge and BOD5 and
COD removal ........................... 91
47 Efficiency of activated sludge process ............. 92
48 Relationship between color removal and chlorine consumed in
chlorination process of 0.1% dyeing wastewaters treated by
activated sludge method ..................... 93
49 Ammonia nitrogen changes in the activated sludge process .... 95
50 Changes of pH values in the anaerobic treatment process of muni-
cipal wastewaters with addition of selected dyes ........ 98
51 Changes of alkalinity in the anaerobic treatment process of muni-
cipal wastewaters with addition of selected dyes ........ 99
52 Laboratory equipment used for continuous studies on anaerobic
and aerobic wastewaters treatment ....... ........ . 100
53 Efficiency of COD removal at the organic load of anaerobic bed
equalled to 0.089 kg/m3-d ................... 101
54 Efficiency of COD removal at the organic load of anaerobic bed
equalled to 0.035 kg/m3-d ................... 102
Vlll
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Number Page
55 COD variations in the anaerobic wastewaters treatment appeared
in different investigation periods 104
57 Changes of alkalinity in the anaerobic wastewater treatment . . 105
58 Color removal variations in the anaerobic wastewater fermen-
tation appeared in different investigation period 107
59 Color removal in the anaerobic wastewater treatment effect of
organic load of anaerobic bed expressed as g COD/dm^-d 107
60 Spectra of the untreated and activated sludge treated wastewaters 108
61 Changes in wastewater spectra as a result of wastewater storage . 109
62 Changes in wastewater spectra in the anaerobic-aerobic waste-
water treatment process Ill
63 Changes in wastewater spectra in the anaerobic-aerobic waste-
water treatment process 112
64 Changes in spectra in visible range of wastewaters due to the
biological method of treatment 113
65 Changes in wastewater spectra due to the biological method of
treatment-effect of HCIO^ addition to the treated wastewater . . 114
66 Color removal by the anaerobic and aerobic wastewater treatment
process 115
67 Changes of organic substances concentration in the anaerobic
and aerobic wastewater treatment process 116
68 Gas production in the anaerobic sludge digestion 119
69 Gas production in the anaerobic sludge digestion 120
70 Gas production in the anaerobic sludge digestion 121
71 Gas production in the anaerobic sludge digestion 122
72 Gas production in the anaerobic sludge digestion 123
73 Gas production in the anaerobic sludge digestion effect of dyes
and assistants concentration 124
74 Gas production rate in the anaerobic sludge digestion 125
75 Gas production rate in the anaerobic sludge digestion 126
IX
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Number 5g
76 Gas production rate in the anaerobic sludge digestion 127
77 Summary concentration of free volatile fatty acids in the
anaerobic digestion process of sludge containing tested dyes
and assistants. Part I 129
77 Summary concentration of free volatile fatty acids in the
anaerobic digestion process of sludge containing tested dyes
and assistants. Part II
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TABLES
Number Page
1 Concentration of Pollutants Contained in Aqueous Solutions
of Dyeing Baths and Assistant Mixtures 5
2 Concentration of Pollutants Contained in Aqueous Solutions
of Dyeing Baths Used in Treatment Processs Study by Adsorption
Method
3 Concentration of Pollutants - Components of Dyeing Wastewaters
Contained in Sewage Sludge Used in Investigation on Anaerobic
Digestion Process
4 Concentrations of Contaminants Contained in the Aquatic Solutions
of Dyeing Baths Mixtures 10
5 List of Tested Conditions of Coagulation 13
6 Characteristics of Sludge Resulting from Coagulation Process of
3% Dyeing Wastewaters with Chosen Doses of Coagulants 31
7 COD Removal and Ozone Consumption Index in Ozonization of
Tested Substrates 41
8 Adsorption of Dyeing Baths by Powdered Activated Carbon and
Bentonite 72
9 Adsorption of Dyeing Wastewater by Activated Carbon Carbopol
WS - Based on Jar Tests 74
10 Parameters of BOD^ and COD Removal Process in Dyeing Wastewater
Treatment by Activated Sludge Method - I Series 88
11 Parameters of BODr Removal Process in Dyeing Wastewater Treat-
ment by Activated Sludge Method - Series II 89
12 Parameters of COD Removal Process in Dyeing Wastewater Treat-
ment by Activated Sludge Method - Series II 90
13 Concentration Range of the Tested Substances 118
XI
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ACKNOWLEDGMENTS
This report was possible because of the cooperation of many people,
The contributions of the following are gratefully acknowledged:
Mrs. Olga Kosarewicz, Eng. MSc.
Mrs. Ewa Wysokinska, Eng. MSc.
Mrs. Natalia Masny, Ph.D.
Mrs. Ingrid Firlus, Eng. MSc.
Mrs. Malgorzata Kosma#a, Eng.
Mrs. Walentyna WrAbel, Eng. MSc.
Mrs. Marcela Grduszak, Eng.
Mrs.. Ewa Hawranek, Eng.
Xll
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SECTION 1
INTRODUCTION
The textile industry has undergone a change in the type of cloth and
fibers being used. There has been a switch from cotton, wool and silk to the
use of synthetic fibers. With this change the type of dye, dispersing agents,
fixers, etc. have changed considerably. Engineers in the wastewater treatment
field need to know about the effects of these new substances on wastewater
treatment systems. In that textile wastes result from a variety of technologi-
cal processes and the use of many different raw materials, the wastes are very
complex.
Although the selection of optimum processes of wastewater treatment should
be accomplished individually for each site, much can be learned from a general
approach to the problem. To gain an insight into the treatability of today's
textile wastes, various combinations of wastewater treatment processes were
investigated. Special emphasis was given to color removal.
The effectiveness of hydrolysis, chemical and biological oxidation, and
adsorption were evaluated. The toxic effects of various dyes and complex
textile wastes on anaerobic digestion were studied.
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SECTION 2
CONCLUSIONS
The effective treatment of textile wastewater with the addition or with-
out municipal wastewater is possible by use of physical and chemical treatment
methods. Color removal is obtained by oxidation using ozone, chlorine or
bromine. During the oxidation process considerable amount of the oxidant is
consumed, which can be substantially decreased by the use of catalysts.
Ultraviolet radiation was found to be a perfect catalyst for the oxidation
reaction with chlorine.
The decomposition of dyes structure can also be obtained in the process
of hydrolysis with lime. In this process a pH above 10 is required. The
addition of lime causes only partial discoloration of wastewater in case of
mixtures of dyes, because of the various effectiveness of the hydrolysis
process in relation to individual dyes.
The biological methods of wastewater treatment show relatively low
effectiveness of color removal from wastewater. Aerobic biochemical pro-
cesses in general did not lead towards substantial structural changes of
dyes. Changes of dyes structure due to aerobic biochemical processes were
studied.
Initiation of dyes decomposition in anaerobic process allows for further
decomposition in subsequent aerobic processes. More attention should be paid
in the future to the two-stage biological treatment method, with anaerobic
process as a first process and for instance, activated sludge as a second
process.
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SECTION 3
RECOMMENDATIONS
The investigations carried out were aimed at the working out of treatment
methods for textile wastewater, especially dyeing wastewater occurring as a
mixture of dye baths only or together with municipal wastewaters.
Based on these studies the following recommendations can be made:
- In case of the mixture of textile wastewater and the municipal in which
textile wastewater is in prevailing amount, the chemical treatment
method should be used. This method consists in the addition of CaO,
and aluminum or ferric sulfate. Considering the high value of pH, the
wastewater must be neutralized before it is discharged into the
receiving water.
- In some cases the treatment of wastewater can be carried out by cata-
lyzed chlorination process.
- The mixture of textile wastewater with a considerable portion of munici-
pal wastewater can be effectively treated by the use of biological
methods,
- To obtain effective removal of color from wastewater, the application
of at least a two-stage process of biological treatment is recommended.
The first stage should be an anaerobic process and the second one an
aerobic process.
- If the textile wastewater contains heavy metals, the toxic effects can
be eliminated by the addition of small doses of CaO to wastewater
entering the primary settling tanks.
- Ozonization or adsorption process on activated carbon should be applied
only if necessary as a final stage of wastewater treatment.
Before the ozonization, or carbon adsorption, the wastewater should be
free of suspended solids.
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SECTION 4
CHARACTERISTICS OF SUBSTRATES
USED FOR THE INVESTIGATIONS
Typical dyes and solutions of dyeing wastewater and mixtures with
municipal wastewater were the basic substrates.
Tap water solutions containing dye baths, and assistants were used for
wastewater treatment by the coagulation method. The investigations were
carried out for three different concentrations of the mixtures, i.e. for
0.1%, 0.5% and 3%. See Table 1. In addition, investigations were done for
0.1% solution, of selected mixtures of dye baths, and assistants and municipal
wastewater.
For treatment by ozonization, chlorination and bromination methods, the
above mentioned solutions of dye baths and assistants of 0.1% and 0.5%
(concentration) were used.
Treatment by ozonization was also carried out separately for 0.005%
distilled water solutions of the following dyes:
- reactive dye - lunasol Rot 5B
- basic dye - special basic red BLN
- weIan dye - weIan brown
- sulfuric dye - sulfuric brown
For wastewater treatment by activated carbon and bentonite adsorption
method, tap water solutions of individual dye baths as well as mixtures of
these solutions were used. The investigations were carried out for the
following concentrations of dye baths:
10% solution of dye bath - for metallized dyes
5% solution of dye bath - for direct, sulfur, dispersed and basic dyes
1% solution of dye bath - for reactive dyes
0.5% solution of dye bath - for chrome dyes
1% solution of mixture of all tested dye baths.
The composition of the individual solutions of dye baths are given in
Table 2. Additional investigations were done on wastewater treatment by
activated carbon adsorption for mixtures of selected water solutions of dye
baths and assistants.
Three different concentrations of the mixture have been tested, i.e.,
0.1%, 0.5%, 3.0%. See Table 1.
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TABLE 1. CONCENTRATION OF POLLUTANTS CONTAINED IN
AQUEOUS SOLUTIONS OF DYEING BATHS AND ASSISTANT MIXTURES
Component
Dyes
Aniline red BLN
Lunasol rot SB
Sulfur brown
We Ian brown
Total dyes concentration
Assistants
Dispersing agent NNO
Elanofor anionic detergent
Lodegal MK - anionic detergent
Rokafenol N8 - nonionic detergent
Siarezanol N2 - sulfate ester detergent
Fixative WOM - cationic detergent
Total assistants concentration
Others
Acetic acid
Sodium sulfide
Sodium carbonate
Sodium sulfate
Concentration in aqueous
solution of dyeing bath
mixture 3 mg/dm3
0.1%
4.17
5.00
3.34
6.67
19.18
2.00
0.33
1.67
0.66
0.08
6.67
11.41
10.00
8.35
8.35
8.00
0.5%
20.85
25.00
16.70
33.35
95.90
10.00
1.65
8.35
3.30
0.40
3.35
57.05
50.0
41.75
41.75
40.00
3.0%
125.1
150.0
100.0
200.0
575.1
60.0
10.0
50.0
19.8
2.4
200.0
342.2
300.0
252.0
252.0
240.0
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TABLE 2. CONCENTRATION OF POLLUTANTS CONTAINED IN AQUEOUS SOLUTIONS OF
DYEING BATHS USED IN TREATMENT PROCESS STUDY BY ADSORPTION METHOD
Tested dyeing bath
Concentration
of tested
dyeing bath %
Components of
dyeing bath
Component
concentration
mg/dm
Metallic-complex
dyeing bath
10
Dye - Polfalan GL brown 2500
Acetic acid 3000
Rokamina S-22 100
Sulforokanol 0-100 200
Rokacet 2000
Sulfur dyeing bath
Dye - Schwefelneu
blau FBI 133
Calcined soda
Siarczanol
Mirabilite
2000
3000
50
10000
Acid-chrome dyeing
bath
0.5
Direct dyeing bath
Reactive dyeing bath
Basic dyeing bath
Dye - Acid-chrome 150
blue ERN
Acetic acid 100
Potassium dichromate 50
Sulforokanol 0-100 150
Dye - Direct brown B 1000
Calcined soda 25
Rokafenol N8 50
Dye - Helaktyn red F4 BAN 300
Calcined soda 200
Mirabilite 600
Rokafenol N8 20
Dye - Aniline blue 1250
RL 50/100
Acetic acid 1500
Rokafenol N8 50
Dispersed dyeing bath
Dye - Synten blue P-BL 3000
Sulforokanol 0-100 100
(continued)
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Table 2 cont.
Tested dyeing bath
Concentration
of tested
dyeing bath %
Components of
dyeing bath
Component
concentration
mg/dm3
Mixture of above
mentioned dyeing
bath
Dyes - Total 528.40
Polfalan brown GL 35.70
Schwefelneu blau FBL 133 57.10
Acid-chrome blue ERN 42.80
Direct brown B 28.60
Helaktyn red F. BAN 42.80
Aniline blue RL 50/100 35.70
Synten blue P-BL 85.70
Assistants - Total 85.67
Rokamina S-22 1.43
Sulforokanol 0-100 48.60
Rokacet 28.50
Siarczanol N-2 1.43
Rokafenol N8 5.71
Acetic acid 114.27
Calcined soda 115.00
Mirabilite 371.42
Potassium dichromate 14.29
For investigations of wastewater treatment by activated sludge method,
municipal wastewaters were used with the addition of selected pollutants
typical for dyeing wastewater. In tests on wastewater treatment by acti-
vated sludge, municipal wastewaters mechanically untreated were used with
addition of one selected substance with the concentration of 300 mg/dm3.
Tested for their influence on activated sludge were lunasol rot 5B, special
basic red BLN, sulfur brown, welan brown, dispersing agent NNO, and fixing
agent WOM. Laboratory investigations of wastewater treatment by activated
sludge method in continuous system were carried out for two different compo-
sitions of wastewater:
(1) Municipal wastewater primarily treated (2 hours sedimentation) with
the addition of six selected wastewater components at concentration of
50 mg/dm of each. Total concentration of selected components was
300 mg/dm3. These compounds have previously been treated individually.
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(2) Municipal wastewater primarily treated (2 hours sedimentation) with
the addition of mixture of the selected solutions of dye baths, and
assistants. The investigations were carried out for 0.1 percent solution
of selected mixture in municipal wastewater. The mixture was composed of
solutions of the following dyes and assistants:
reactive dye - lunasol Rot SB
basic dye - special basic red BLN
welan dye - welan brown
sulfur dye - sulfur brown
fixing agent WOM
dispersing agent NNO
Total concentration of dyes and assistants reached about 30 mg/dm3.
For batch tests of wastewater treatment by anaerobic digestion, municipal
wastewater untreated mechanically was used with addition of one selected sub-
stance with the concentration of 300 rag/dm^, similar to the tests on waste-
water treatment by activated sludge method.
In laboratory investigations on continuous wastewater treatment by the
anaerobic digestion method using biological filters, municipal wastewater
treated mechanically was used with the addition of reactive dye - lunasol
Rot 5B with concentration of 300 mg/dm^.
In test investigations on the influence of selected pollutants contained
in dyeing wastewater on the course of anaerobic digestion process of waste-
water sludges, the wastewater sludges from primary sedimentation tanks were
used with the addition of one selected component or mixture of dye baths.
For each added substance as well as for the mixture, the influence of differ-
ent concentrations was studied.
The components added in particular tests are listed in Tables 3 and 4.
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TABLE 3. CONCENTRATION OF POLLUTANTS - COMPONENTS OF
DYEING WASTEWATERS CONTAINED IN SEWAGE SLUDGE
USED IN INVESTIGATION ON ANAEROBIC DIGESTION PROCESS
Series
number
I
III
I
III
I
III
I
III
II
III
II
III
II
III
II
III
II
III
II
II
II
III
II
III
Component
Reactive dye - Lunasol
rot 5B
Dispersed dye - Polanit
rot BRL -
Synten yellow
Basic dye - Aniline red BLN
Metallic - complex dye
- Polfalan green 2 BL
Direct dye
- Helion yellow BRL
Acid dye - Folan red B
- Folan red B
Acid chrome dye -
- acid chrome red B
Sulfur dye -
- Sulfur brown
Special dye for wool
dyeing - Lasting red PGL
Welan dye - Welan brown
Assistant - Dispersor NNO
Assistant - Fixative WOM
Assistant - Elanofor
Mixture of dyeing bath
Concentration
of component g/dm3
3.0
0.3
3.0
0.3
3.0
0.3
3.0
0.3
0.3
3.0
0.3
3.0
0.3
3.0
0.3
3.0
0.3
3.0
0.3
0.3
0.3
3.0
0.3
0.3
10.0
1.0
10.0
1.0
10.0
1.0
10.0
1.0
1.0
6.0
1.0
6.0
1.0
6.0
1.0
6.0
1.0
6.0
1.0
1.0
1.0
6.0
1.0
1.0
25.0
3.0
25.0
3.0
30.0
3.0
30.0
3.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
5.0
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TABLE 4. CONCENTRATIONS OF CONTAMINANTS CONTAINED IN
THE AQUATIC SOLUTIONS OF DYEING BATHS MIXTURES
Components of dyeing bath
Concentration of component
in aquatic solutions of
dyeing bath mixture, mg/dm
0.3'
1.0*
5.0%
Aniline red BLN
Lunasol rot 5B
Sulfur brown
WeIan brown
Total dye concentration
Assistants:
Dispersing agent NNO
Elanofol - anionic detergent
Lodegal MK - anionic detergent
Rokafenol N8 - nonionic detergent
Siarczanol N2 - sulfate ester detergent
Fixative WOM - cationic detergent
Total assistants concentration
Others:
Acetic acid
Sodium sulfide
Sodium carbonate
Sodium sulfate
12.51
15.00
10.02
20.01
57.54
6.0
0.99
5.01
1.98
0.24
20.01
34.23
30.0
25.05
25.04
24.0
41.7
50.0
33.4
66.7
191.8
20.0
3.3
16.7
6.6
0.8
66.7
114.1
100.0
83.5
83.5
80.0
208.5
250.0
167.0
333.5
959.0
100.0
16.5
83.5
33.0
4.0
333.5
570.5
500.0
417.5
417.5
400.0
10
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SECTION 5
PHYSICAL AND CHEMICAL TREATMENT METHODS OF DYEING WASTEWATERS
5.1 COAGULATION
Methodology and Scope of the Investigation
The purpose of the technological investigations was to determine the
efficiency of dyeing wastewater treatment using the coagulation method. The
investigations were carried out on laboratory scale using aluminium and
ferrous sulfates as coagulants with pH adjustment in the range from 8-12,
with solution of CaO. In addition, coagulation tests were accomplished using
FeCl3 at pH of 8.0 and A12(S04)3 at pH = 6.8. Also tests of coagulation using
fly ashes were carried out , and tests on the coagulation using A12(S04)- or
Fed, with assistance of fly ashes. Additionally the influence of pH ranging
from 11.96 to 13.00 on coagulation efficiency with the use of CaO was studied.
The investigations were carried out for dyeing wastewater composed of
synthetically prepared mixture of various dye baths, according to the recipe
applied at textile manufacturing plants.
The criterion of selection of appropriate dye groups, as well as assist-
ants for the dye baths, was the applicability of a given component in techno-
logical processes of the textile industry.
Tests were carried out using the equipment in static conditions.
To obtain optimum conditions of the process, the coagulation was
accomplished on large laboratory scale using 35 liters of wastewater of
3 percent concentration.
Both in tests and in laboratory investigations, the following duration
times for the individual stages of coagulation were used:
rapid mixing - 3 min
slow mixing - 20 min
sedimentation - 120 min
Mechanical mixers were used for rapid and slow mixing in test investi-
gations, while on large laboratory scale examinations, compressed air was
applied.
11
-------
The coagulation process was performed at ambient temperature and in
addition for coagulation using CaO also at the temperature of 95 °C.
To establish the efficiency of the coagulation process, the following
physical and chemical determinations in wastewater samples were carried out
before and after coagulation: pH, temperature, color, turbidity, the volume
of precipitated sludge (cm3/dra3) after 2 hours sedimentation.
The tests run are presented in Table 5.
Discussion of the Results
Coagulation of dyeing wastewater was carried out mainly in order to
remove color and turbidity from these wastewaters. Considering the high
variety of the dyes and assistants used, reports were encountered containing
extremely different conclusions concerning treatment effects of the coagula-
tion process. Also, the mechanism of color removal was not yet sufficiently
explained. Zuckermann and Molof (1) suggested that chemical hydrolysis takes
place after the addition of calcium hydroxide and increased pH. Zuckermann
and Molof (1) stated that chemical hydrolysis changes high molecular organic
molecules (dyes) into low molecular ones.
In the light of Zuckermann's and Moloffs statements (1), of special con-
cern in the investigation was the effects of color removal as a result of
lime addition to dyeing wastewater solution.
The tested solution of dyeing wastewater was composed of, as it was
previously stated, four dyes from each of the groups of reactive, basic, welan
and sulfur dyes.
Reactive dyes are characterized by good water solubility and quite easily
hydrolyze turning into insoluble form. Hydroxyl ions react in water solution
with reactive groups of a dye causing its hydrolysis. The hydrolyzed dye
cannot react with fiber and can only settle on its surface.
Basic dyes in the form of base are insoluble in water. They form water
soluble salts, e.g., hydrochlorides or acetates in reaction with inorganic or
organic acids. In water medium these salts dissociate into dyeing cation
and anion of acid radical
B - NH2 • HC1 <"=- CB - HN3)+ + Cl~
Therefore increasing pH of the solution through lime addition should
convert the basic dye into insoluble form and precipitate them from the
solution.
Sulfur brown dye used in the investigations is made from the reaction of
aromatic amines, and nitrocompounds with sulfur. In its molecule, the
thiazole rings are such as:
12
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Sulfur dyes are usually insoluble in water. In order to convert them
into soluble form, they are usually reduced with Na2S in alkaline medium, and
the sodium salt of sulfur dye is formed.
> 2B - SNa
The reduced form of the dye is oxidized relatively easily with atmo-
spheric oxygen which converts it into the insoluble form.
°2
2B - SNa ——> B - S - S - B
oxid.
In this investigation it seems that quite a considerable part of the dye
was converted into insoluble form during the preparation of all dye bath
mixtures. Also, probably part of the sulfur dye oxidizes to insoluble form
during subsequent operations of diluting and mixing.
The fourth group of the used dyes, welan dyes, consist of a mixture of
dispersed and metallic dyes in the relation 1:2. Molecules of dispersed dyes
do not contain sulpho or carboxyl groups. Before use, dyes are converted by
dispersing agents into suspension form. Metallic dyes are soluble in water,
and this property is due to sulfo group - S03H or sulfonamide group - S02NH2.
It seems that on account of their structure, welan dyes do not hydrolize,
however, they can be removed in coagulation process as a result of adsorption
of the dispersed suspended dye and of electrokinetic influence of the coagu-
lant on the anion of metallic dye.
Analysis of dyes composing dye baths were performed after the addition
of calcium hydroxide to determine how effectively the color was removed. It
was possible to remove a considerable part of color from tested solutions
through lime addition. The color removed increases with the increase of lime
dose, while it decreases with the increase of dyeing wastewater concentration.
This relationship is shown in Fig. 1.
The very distinct decrease of color removal efficiency with the increase
of dyeing wastewater concentration prompted deeper analysis of the problem for
the individual concentrations.
When presenting the data as it is done in Fig. 2a, the effect of color
removal on the dependence of the CaO dose for 0.1 percent solution is clearly
seen. There is a very rapid increase of color removal with the increase of
coagulant dose. In practice a dose of 0.300 to 0.400 g/dnr is quite suffi-
cient for the effective wastewater decolorization.
14
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Rys 1. Efekty koagulacji s
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16
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Total color removal by CaO addition was not possible. For a dose of 0.3
to 0.4 g/dm3 about 83 percent color removal was obtained as determined with
the dilution method (Fig. 2a) and for doses from 4.0 to 10.0 g/dm3 of CaO a
constant color removal of 92 percent was obtained.
The addition of aluminum sulfate and ferrous sulfate, coagulants, were
studied.
When analyzing Fig. 2b, where the investigations results are presented
with CaO addition in a dose of 0.5 and 1.0 g/dm*, and A12(S04) addition in
the range from 0.02 to 1.5 g/dm3, practically no effects of color removal
increase were noted. In fact, extremely strange dyes behaviour was noticed.
While CaO addition in tjie amount of 4.0 g/dm3 as it was previously men-
tioned, 92 percent of color removal was obtained, the additional dose of
0.02 to 1.5 g/dm3 of A^CSO.)^ ^^ not nave an>r additional influence on the
color removal.
The effects of ferrous sulfate addition on the degree of color removal
looked somewhat different and the results are shown in Fig. 2d, e, f, and g.
The satisfactory color removal was reached with addition of FeSO. in dose of
0.03 to 0.05 g/dm3 and with simultaneous addition of CaO in dose of 0.3 to
0.4 g/dm3. Therefore with a total dose of 0.33 to 0.45 g/dm3 of coagulant it
is possible to remove 90 percent of the color.
Practically total color removal from 0.1 percent solution of dyeing waste-
water was obtained with the addition of 1.0 g/dm3 of CaO, and FeS04 addition
in a dose of 0.5 g/dm3 and above. See Fig. 2f and 2g.
When testing the solution of dyeing wastewater of 0.5 percent concentra-
tion, the characteristic fact is that with addition of CaO, a similar form of
color removal effects was noted (Fig. 3a) as with dyeing wastewater of 0.1
percent concentration.
In contradiction to the effects obtained for a 0.1 percent solution, in
case of 0.5 percent solution of dyeing wastewater the addition of aluminum
sulfate by coagulation with the dose of 4.0 to 6.0 g/dm3 of CaO caused quite
distinct increase of color removal effect (Fig. 3b and 3c). Maximum effects
of color removal with the addition of aluminum sulfate and calcium hydroxide
equalled about 96 percent; therefore, total color removal was not obtained.
Besides CaO, when dosing FeS04, the addition of 0.3 or 0.4 g/dm3 of CaO
and 0.07 to 0.1 g/dm3 of FeS04 is considered as the smallest dose leading
towards obtaining satisfactory effects. This sums up to be a total addition
of coagulants in the range between 0.4 and 0.47 g/dm3.
Comparing this dose with the one obtained for solution of 0.1 percent of
dyeing wastewater, more general conclusions can be drawn that for relatively
diluted dye solution, CaO dose of 0.1 g/dm3 and FeS04 dose of 0.07 g/dm3
give effective hydrolysis and coagulation.
17
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A doubt that the hydrolysis process really takes place was dispelled to
a certain degree by examinations of color removal with only the addition of
aluminum sulfate to dyeing wastewater solution (Fig. 3d). Investigations
with and without pH adjustment to 6.8 showed that above the dose of 0.02 g/dm3
A12(S04)3, the color removal was not increased but equal to 40 percent by
the comparison method and 20 percent by the dilution method.
Therefore, it can be supposed that a minute part of the dyes is subject
to electrokinetic forces during the coagulation process. Also, a hypothesis
can be made that there is a lack of sufficient number of colloidal molecules,
which during the aggregation process caused simultaneous removal of a part of
the dyes in the adsorption process. Such hypothesis results also to some
extent from the comparison of literature data with our own investigations
(not included in the program of presently reported works) concerning actual
existing wastewater. Because for such a type of wastewater, effective coagu-
lation and color removal just by the addition of only aluminum sulfate in
relatively low doses to about 0.2 g/dm3 is very often noted.
Also, it should be remembered that in actual existing wastewater, a
hydrolysis process could take place during mixing various types of wastewater,
including those with increased pH.
The importance of chemical processes resulting from alkalizing environ-
ment appears to be very important in the case of CaO addition into 3 percent
dyeing wastewater solution. When analyzing Fig. 4a, the complete lack of
color removal with low doses of CaO can be seen. Only the CaO dose of
1.0 g/dm causes considerable color removal of 45 percent. The color removal
increases to the value of 70 percent together with the increase of CaO dose
to 10.0 g/dm3. Considering the large dose, the color removal effect is little,
Trials have been undertaken of increasing color removal by raising temperature
up to 95 °C in the coagulation process (hydrolysis) by means of CaO. However,
no positive effects were obtained, because the increase of color removal was
only 10 percent.
On the other hand, a positive effect of the addition of aluminum sulfate
was obtained. With a dose of 6.0 and 10.0 g/dm3 of CaO (Fig. 4b and 4c) for
relatively low doses of A^tSO^j, a very good decolorization was reached with
96 percent of color removal.
Similarly, perfect effects of color removal were obtained through joint
action of calcium hydroxide and FeSO^ (Fig. 4e and 4f). However, this effect
was possible with only very large doses of CaO above 6.0 g/dm3. Fig. 4e and
4f show that color removal of 99 percent is possible either with the dose of
8.0 g/dm3 of CaO and 1.0 g/dm3 of FeS04 or with the dose of 10.0 g/dm3 of CaO
and 0.5 g/dm3 of FeS04.
In compliance with suppositions arising from the analysis of properties
of tested dyes, as a result of hydrolysis connected with CaO addition to
dyeing wastewater solutions, the individual dyes removal takes place in
various degrees. This fact is stated on the basis of observations of color
19
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tint changes of coagulated sample, in comparison with standards prepared by
dilution.
It can be considered that additional proof for hydrolysis process result-
ing from CaO addition to wastewater is a complete lack of color removal in
case of the addition of calcium carbonate to dyeing wastewater solution.
Joint action of calcium hydroxide and ferrous sulfate, ferrous chloride,
or aluminium sulfate was found to be indispensable for turbidity removal
from wastewater. See Fig. 5, 6, and 7.
However, some exceptional cases were recorded. For a dose of 4.0 g/dm3
of CaO together with increasing amounts of aluminum sulfate, a decrease of
turbidity removal was obtained both for 0.1 and 0.5 percent of dyeing waste-
water solution. See Fig. 5c and 6a. Also for the same dose of CaO 4.0 g/dm ,
addition of FeS04 gave a high efficiency of coagulation, while for other doses
of CaO, only a very small positive effect on turbidity removal was noted. See
Fig. 5g.
Increasing pH from 11.96 to 13.00 for solutions of 0.1, 0.5 and 3.0
percent concentrations, into which 0.3 or 1.0 g/dm^ of CaO had been intro-
duced before, very small changes of color removal were obtained. Changes of
color removal determined by the comparison method for 0.1 percent solution
amounted to +_ 2 percent. For 0.5 percent the differences in color removal
were a maximum of 8 percent. The obtained effect of pH increase in coagu-
lated wastewater with CaO addition is presented in Fig. 8.
Changing pH of dyes solution before their coagulation by means of carbon
dioxide saturation of the wastewater does not change the treatment efficiency
in comparison with samples not undergoing C02 saturation. The comparison of
the obtained results are presented in Fig. 9 and 3a.
On the other hand, neutralization to pH = 7.6 after separation of the
precipitate resulting from the coagulation of the wastewater, certain increase
of color removal was noticed. Therefore, it can be stated with a full cer-
tainty, that CaO addition and pH increase resulting from it causes permanent
changes in dyes structure and properties. Calcium carbonate precipitating
during wastewater neutralization process contributes additionally to waste-
water clarification. This effect amounts to turbidity removal equaling at
least to 90 percent. See Fig. 10. Probably part of the dyes are being
absorbed on CaC03 suspension.
Toward further explanation of the phenomenon taking place in the coagu-
lation process by means of CaO, a stage of free mixing with C02 gas until pH
reached neutral was carried out. The results presented in Fig. 11 show
explicitly a distinct setback of the dyes removal process. Calcium carbonate
generated in the C02 saturation process eliminated free hydroxide ions from
the solution.
The addition of fly ashes in the range of 0.05-0.5 g/dm3 into wastewater
coagulated with Fed* or A12(SO.)» was studied. For tested doses no substan-
tial color removal was noted, as shown in Fig. 12.
21
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Rys 7. Efekt usuniqcia mqtnodci w procesie koagulacji 3% ^ciek6w
farbiarskich.
Figure 7. Turbidity removal by coagulation method 3% dyeing wastewaters,
24
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SATUBACIA COZ &CIFKOW pttceo KOAOULACJA, DO pH - 6
COa SATURATION or DVCINO WAfiTCWArBOe BCFORC
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Rys 9. Efekt oczyszczania 0.5% ^ciek6w farbiarskich w procesach
saturacji C02 i koagulacji r6znymi dawkami CaO*
Figure 9. Effects of 0.5% dyeing wastewaters treatment process by C02
saturation and coagulation using various CaO doses.
26
-------
SATURACJA C02 SCtEKOW ZDEKAWTOWAMVCU PC KCMeULACJi DO pH 7,16
C02 SATURATION OFCOA«ULATEP WASTE WATERS PE*n3«MEt> TO pH * 7.16
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VAWKA CftO
70OO
O »AI*WA (MCTOOA »0«ONVNAN ) - COLOUR (COMf**l«ON MKTHOo)
• ftAKWA (MtTOOA NO«CI«4CZ«N) - COL.OUM (DILUTION METHOD)
X Mf,T*OOC. ~ TURBIDITY
Rys 10. Efekt oczyszczania 0.5% ^ciek6w farbiarskich w procesach
koagulacju rdznymi dawkami CaO i saturacji C02.
Figure 10. Effects of 0.5% dyeing wastewaters treatment process by-
coagulation using various CaO doses and by C02 saturation
27
-------
SATURACJA CQ( DO
W PROCES1E
pH - 748 AFM.IFD
400
K.
I
BARVM (MCrOOA *Of«OWNAIJ} - COLOUR ( COHMIU8OH
•AJtWA (MBTOOfc MCOUtCZCN} - COLOUR ( MLUTIOH MBTHOD)
M%TMO>C - TXMM1XTV
O«J%TO«C wvm^comcH COADOW - WOLUMC OP
Rys 11. Efekt oczyszczania 0.5% ^ciek6w farbiarskich w procesie
koagulacji r*znymi dawkama CaO wspomaganej saturacja C02g
Figure 11. Effects of 0.5% dyeing wastewaters treatment process by CaO
coagulation and CC^ saturation simultaneously used.
28
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29
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In order to determine the efficiency of detergent and assistants removal
by coagulation using 6.0 g/dm3 of lime milk, the tests were accomplished for
0.5 percent water solutions of the individual substances. The results of the
tests evaluated on the basis of COD showed 2.5-5 percent removal of: Lodegal
MK, dispersing agent NNO, Rokamin S22, and 12.3 percent for Sulfanol N2 and
22.4 percent for Elanofor.
When repeating selected cases of test investigations in larger scale
equipment of the volume of 35 dm3, similar effects of treatment were recorded
with both higher and lower effects. Control tests on large laboratory scale
were accomplished for 3 percent solutions of dyeing wastewater.
Treatment effects were examined for three cases:
1. CaO - 6.0 g/dm3
2. CaO - 8.0 g/dm3
+ FeS04 0.5 g/dm3
3. CaO - 6.0 g/dm3
+ A12(S04)3 0.25 g/dm3
The effects of color and turbidity removal obtained during wastewater coagu-
lation using lime milk in a dose of 6.0 g/dm3 accomplished on laboratory scale
were a little higher and equaled to: 80 percent of color and 99.6 percent of
turbidity removal. The achieved increase of treatment can be explained most
probably by a better mixing of wastewater by means of compressed air.
The effects of coagulation using FeS04 and CaO defined by color reduction
were slightly lower by 9 percent from these obtained in the tests and reached
90 percent of color removal. The efficiency of turbidity removal was high and
reached practically 100 percent.
The efficiency of wastewater coagulation with A12(S04)3 as a coagulant
and CaO defined by color reduction increased by 5 percent from the tests
results and reached 95 percent.
The sludges produced due to wastewater coagulation by using the three
following coagulants were studied:
1.5% of volume - CaO as coagulant
9.0% of volume - using FeS04 + CaO as coagulant
4.0% of volume - using A12(S04)3 + CaO as coagulant.
Sludges generated in coagulation were characterized by a low resistance
coefficient to filtration. Dewatering feasibility of these sludges was
described in Table 6.
30
-------
TABLE 6. CHARACTERISTICS OF SLUDGE RESULTING FROM COAGULATION PROCESS
OF 3% DYEING WASTEWATERS WITH CHOSEN DOSES OF COAGULANTS
Coagulant dosage,
Determination
Volume of sludge
2 h
6 h
Total solids
Volatile total solids
Volatile total solids
Sludge volume index
Coefficient of specific
resistance to filtration
Time of capillary
filtration C-S*T
Sludge thickening
0.5 h
1.0 h
2.0 h
3.0 h
4.0 h
5.0 h
6.0 h
24 h
Unit
cm3 /dm3
g/dm3
g/dm3
cm3/g
m/kg
s
cm3 /dm3
11
it
it
it
it
n
tt
CaO
6000
15.2
15.2
102.08
10.07
9.88
9.6
4xlOu
96.9
984
960
928
896
872
840
800
528
FeS04
500
CaO
8000
90.9
63.6
52.56
17.92
15.1
17.9
2.7xlOu
52.1
910
820
710
600
-
530
390
mg/dm5
A12(S04)3
250
CaO
6000
39.4
33.3
99.17
13.17
13.3
9.5
4.3X1011
74.1
952
892
856
808
768
720
472
Sludge hydration
estimated after 6 h
sedimentation
Sludge hydration
estimated after
specific resistance to
filtration measurement
88.5
90.7
91.0
58.3
63.2
60.9
31
-------
Considering very high optimum doses of CaO necessary for achieving
adequate efficiency of coagulation, the investigations were undertaken con-
cerning possibilities of multiple reuse of lime C2)-
- Sludges precipitated after coagulation were dewatered and roasted at
a temperature of 550 °C and then reused again for coagulation. This
process was repeated twice. The efficiency of pollution removal for
primary and secondary treated sludges was similar.
- Sludges precipitated after coagulation were separated from treated
wastewater through water decanting and reused as a coagulant for raw
wastewater sample. The process was repeated twice, and then sludges
were roasted at a temperature of 550 °C.
The roasted sludges were reused for wastewater coagulation, and after
four time recycling of hydrated sludge it was roasted again. The roasted
sludges were used again for coagulation. The effects of coagulation pre-
sented in Fig. 13 proved the feasibility of 7 times recycling of lime with
similar efficiency of color removal. The 8th recycling process resulted in
3 times lower efficiency of color removal.
The coagulation process causes COD removal in the range between 10 and
50 percent.
Large amounts of sludges generated in the coagulation process reaching
4 kg/m have an average 90 percent of hydration.
5.2 OZONIZATION
Methods and Range of Investigations
The investigations were directed towards determination of ozonization
usability for dyeing wastewater treatment.
Tests were carried out for dyeing wastewater of 0.1 percent and 0.5 per-
cent. In addition, the effects of ozonization were defined for 0.005 percent
solutions of individual dyes composing dyeing wastewater. The pH influence
was also tested in the range from 3.5 to 12 on ozonization effects for 0.1
percent dyeing wastewater. Tests were carried out in laboratory installations
in static conditions. See Fig. 14. Ozone was produced in an ozone generator
using air as the oxygen source. Tests were accomplished at ozone generation
flow of 2.2 and 9.2 mg/min using ozonization time from 5 to 60 minutes. Ozone
was determined quantitatively by the iodometric method. The ozonization
effects evaluated were changes in color, COD, and pH.
Discussion of Investigations Results
The test investigations showed that color removal is proportional to
ozonization time (Fig. 15) and ozone dose (Fig. 16). After 30-minutes contact
and at the ozonization flow of 2.2 mg/min, the removed color ranged from
20 percent to 86 percent depending on substrate undergoing tests (Fig. 17).
Ozone introduction at a flow of about 9.0 mg/min improved considerably these
32
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33 30 0>
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4OO -,
60.
(HCTOOA
•ARWA (itrrOOA
ChZT - COD
or LIMC MCCVCLING
NUM««lt 0* UHI ACCVCUNQ
- COfcOUR ( COM^ARI»ON ftfTHOOj
' COLOUR (oiLtmON MffTHOo)
WVTtt^CONVCM 06AOOW - VOLUMF Of *WOQC
KOAGUIACJ* OSADEH UWOOMlOKVN POMftTAVIH W rOV*Z*OIHti I
COACULA-T'ON BY THC U9C OF «U|OCf QrMKKATIMk FROM THC MtCylOUC COAGULATION OROCBW
KOAOULACJA OSADTN WrtPALOIWH PO*9TAiXf* W POPRcCPHlCJ KOACUMCJI
OOAOULArtON W THC U*K OF O• WATERBD AND MOA*T*D SLUCMC AfrWAATlNCh ntOM TW PACVIOUS
bOAGULATfON PROCCSC
Rys 13. Efekty koagulacji 0.1% ^ciekAw farbiarskich przy uzyciu
CaO ^wiezego i regenerowanego. Dawka CaO - 6.0 g/dm^.
Figure 13. Efficiency of the coagulation process performed by the multiple
reuse of lime. Dose of CaO to 6.0 g/dm3 0.1% dyeing wastewaters
33
-------
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p
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34
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100,
80
60
40
20
10
20
50 GO
CZAS OZOMOWAN1A r__;-.n
OZONATION TIME LminJ
O 0,1 [%J SCIEKI
A Osryi DvetNB WASTVWATERS
^^^— 2,2
«ZV»KO«C WYTWAftZAMlA OZONU
OF OZONE poooucnoM
Rys 15. Efekty usuni^cia barwy ze ^ciek6w farbiarskich w
zalezno^ci od czasu ozonowania.
Figure 15. Relationship between color removal and ozonation
time in dyeing wastewaters ozonation process -
35
-------
100
80,
|< 60
< o
£D S
UJ
< CL
h-
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40 J
20
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20 40 60 80
ZUZYTA DAWKA OZONU
OZONE CONSUMED
100
0 0.1% 3cieki farbiarskie
0.1% Dyeing wastewaters
x 0.5% 3cieki farbiarskie
0.5% Dyeing wastewaters
Rys 16. Efekty usuniecia barwy ze sciekow farbiarskich w zaleznosci
od zuzytej dawki ozonu»
Figure 16. Color removal by ozonation effect of ozone consumed*
36
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37
-------
effects, especially for 0.5 percent wastewater for which maximum 75 percent
of color removal were achieved (Fig. 17). Figure 18 shows the relationship
between the amount of 03 feed and the color removed. Ozonization of water
solutions of the individual dyes showed that reactive dye had the highest
oxidizability (Fig. 17 and 19). The remaining three dyes, i.e., sulfur, basic
and welan were removed during 30 minutes in identical degree. However,differ-
ences in their removal rate were observed after 60 minutes (Fig. 17). The
index of ozone consumption for individual dye removal confirms high oxidiz-
ability of reactive dye. In the case of reactive dye, the 03 consumed per
unit of dye removed (0.14 to 0.33 mg of O^/mg) is the lowest among four tested
dyes (Table 7).
As a result of the ozonization process, changes take place in the
molecular configuration of dyes with partial oxidation of the carbon atoms.
The observed changes in spectrum UV-Vis confirm this fact.
It was observed that color decay in ozonization process was accompanied
by weakening of spectral bands or their complete decay. The ozone influence
could be seen the soonest and clearest in the reactive dye.
The best effects of color removal were obtained for the reactive dye.
Color decay was accompanied by the decay of series of spectral bands in UV-
Vis spectrum (Fig. 20).
The infrared spectrum obtained from reactive dye bath before ozonization
and after 15 and 30 minutes of ozonization showed an adsorption at 1380 -
1375 cm"1. As the ozonization proceeded there was a diminution of the wide
band in "dactyloscopic area," and the appearance of a band in the range of
1460 - 1390 cm"1, and weakening of the band in the range of 840 - 730 cur1.
The peak at 870 cm"1 and adsorption above the frequency of 1400 cm"1 are due
to the stretching vibration of carbonates (Fig. 21).
The influence of pH changes on ozonization effects was tested for 0.1
percent dyeing wastewater by 30 minutes contact with an ozone flow of
2.35 mg/min. Based on the obtained results, it can be stated that changing
wastewater pH with the addition of H2S04 or NaOH in the range of 3.5 to 9.0
does not affect the improvement of ozonization. Increase of pH up to 11 and
12 caused permanent, irreversible color removal of 20 percent and 56 percent,
respectively.
Combining the alkalizing processes at pH 12 and ozonization process gave
94 percent of color removal. See Fig. 17 and 22. The positive effect of pH
increase up to 12.45 by the addition of Ca(OH)2 in ozonization process was
observed by Reicherter and Sontheimer (3). These authors are of the opinion
that pH increase leads towards quick decomposition of ozone and precipitation
of partially oxidized organic substances.
However, in the case of our investigations, it seems that increased pH
first causes hydrolysis of part of the dyes. This conclusion is according
to results from tests on wastewater coagulation in Section 5.1. Oxidation
takes place at lower pH values.
38
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1-1
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TJ
O-
X
cU
rt ^i -
•H -H- C
o c o
cr g -H
•H. h -P
C nj eS
3 ,n ft
tn . o
3 TO M
S o
3 O
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[%] vMava vi Si NO sn
•H
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39
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24
16 20
XUZVTA DAWKA OZONU j~ .
CONSUMED L"^ /dm J
o Barwnki reaktywny
A Barwnik zasadowy
X Barwnki siarkowy
• Barwnik welanowy
Reactive dye
Basic dye
Sulfur dye
WeIan dye
Rys 19. Efekty usuni^cia barwy z 0.005% roztwor6w barwnik6w w
zaleznodci od zuzytej dawki ozonu-
Figure 19. Relationship between color removal and ozone consumed
in 0.005% dyes solutions ozonation process-
40
-------
TABLE 7. COD REMOVAL, AND OZONE CONSUMPTION INDEX
IN OZONIZATION OF TESTED SUBSTRATES
Substrate
Dyeing wastewater
Dyeing wastewater
Water solutions of
dyes
reactive
basic
we Ian
sulfur
Concen-
tration
%
0.1
0.5
0.005
0.005
0.005
0.005
COD removed
from filteredx
sample
%
after after
5 min 60 min
27.3
10.6XX
56.2 11.0
27.3 18.2
4.8
28.6 14.3
Ozone consumed
for dye removed
mg of 03/mg
after
15 min
-
-
0.14
0.38
0.58
0.39
after
60 min
-
-
0.33
0.67
0.48
0.50
xfilter paper
xxafter 30 minutes
41
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o:
UJ
CD
Of
O
UJ
CO
(J
CD
o:
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V)
CO
190
50
FALI - WAVE LENGTH Qnm]
Rys 20. Widma wodnego roztworu barvmika reaktywnego-
I. Przed ozonowaniem
II. PO 15 minutach ozonowania
III. PO 30 minutach ozonowania
Figure 20. Spectra of the reactive dye water solution.
I. Untreated
II. After IS minutes of ozonization
III. After 30 minutes ozonization
42
-------
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d
f*
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•i
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(I)
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pH u
O '•UftOaDNOWMIHEM - M*0*e OZOMMXM
Rys 22. Wptyw zmian pH na efekt usunigcia barwy ze
farbiarskich 0.1%>.
Figure 22. Removal of color by ozonation - effect of pH variations
0.1% dyeing wastewaters.
44
-------
The ozonization process did not cause high changes in COD. Maximum
values of COD removed from the filtered sample were varied for various sub-
strates. For example, they were: for 0.1 percent dyeing wastewater - 27.3
percent after 60 minutes of ozonization, and for 0.5 dyeing wastewater - 10.6
percent after 30 minutes of ozonization (Table 7). COD removal in the ozon-
ization process depended on ozonization time. Generally, shorter ozonization
time and smaller ozone dose caused higher COD removal.
5.3 CHLORINATION
Methods and Range of Investigations
Chlorine and its compounds, on account of their oxidizing and disinfect-
ing properties, are used in wastewater treatment not only for municipal but
more and more frequently for industrial wastewaters (4). The investigations
were carried out with laboratory equipment in static conditions using contact
time with chlorine from 5 minutes to 24 hours, and a chlorine dose from 5 to
1000 mg/dm3. See Fig. 23 for testing equipment. Samples catalyzed with
ultraviolet color were irradiated by a quartz lamp at contact time from 2.5
to 15 minutes. Besides investigations were carried out on chlorination pro-
cess preceded by CaO coagulation with and without neutralization. Chlorine
was determined by the iodometric method. Wastewater treatment effects were
defined on the basis of following indices: color, COD, BOD5, anionic deter-
gents, and pH. The investigations were carried out at room temperature equal
to 20 °C.
Discussion of the Investigations Results
As it had been anticipated as a result of oxidation process with chlorine,
changes were observed in wastewater color as well as considerable percentage
of color removal. Oxidation can either break the dye aromatic structure or
change the functional groups.
Technological investigations seem to indicate that the oxidation process
changed the chromophoric group. These positions were confirmed by chromato-
graphic analyses.
The oxidation process with use of chlorinated lime solution (Fig. 24)
indicates a relatively low rate of oxidation. From the shape of the curve,
it can be concluded that several oxidation reactions take place simultaneously
at various rates. Chlorine consumption was proportional to the removed color
(Fig., 25) independently of changes in chlorine dose from 5 to 1000 mg/dm3 or
of varying contact time from 15 rain to 24 hrs.
Efficiency of oxidation with chlorine depends considerably on pH of the
solution in which the reaction will take place. When chlorinated lime was
used, the pH was distinctly alkaline in range from 9.42 to 10.34. When using
chlorine water, pH was in acid range from 3.20 to 5.36.
45
-------
Rys 23. Aparatura do wytwarzania wody chlorowej-
Figure 23. Testing equipment for chlorine water production.
46
-------
20 24
KONTAKnj Z CHUHUM
CHLOKIMAnON TIHC
29
Rys 24. Zaleznos'c' efektu usuniqcia barwy ze ^ciekbw farbiarskich 0.1-
od czasu kontaktu z chlorem przy zastosowaniu roztworu wapna
chlorowanego.
Figure 24. Relationship between color removal and chlorination
time in 0.1% dyeing wastewaters chlorination process using
lime chlorinated solution as an oxidizer.
47
-------
1*0
10
20 25
XUZTTA MWKACHIOMU [mg/dnAJ
CZM NOMTMC1U ZOOOMKH 4R Tminl
•TANTCMLOHMAnoMTINC 'O |_m»nj
~> 41 t"i.*f
•* 24 fh]
CHLOMMC
VMfeA DOBWMMHi DAWKA OU0MU
Rys 25. Zalezno3
-------
When using chlorine water, considerably higher reaction rates were
achieved. With a very small dose of chlorine in the range from 20 to 50 mg/dm3
and a contact time of 15 minutes, the decoloration process was practically
finished. The comparison between color removal and chlorine consumed using
chlorinated lime and chlorine water is shown in Fig. 25 and 26. For example,
when comparing color removal at a consumed amount of 20 mg/dro3 of chlorine,
there was only 53 percent color removal using chlorinated lime as contrasted
to 99 percent using chlorine water.
The process of dyes oxidation with chlorine can be accelerated substan-
tially with UV radiation (Fig. 27 and 27a).
Chlorine consumption in the reaction catalyzed with UV light was higher
by about 15 percent than in the process without catalyst at the identical
color removal effects. Higher chlorine consumption was caused probably by
oxidation or chlorination of the remaining colorless pollutants contained in
wastewater (detergents and assistants), and also by intensifying destruction
of dyes molecules.
This thesis is also confirmed by the fact of higher chlorine consumption
in the process using ultraviolet radiation at the use of a larger chlorine dose
of 100 mg/dm3 than at a dose of 50 mg/dm3 of chlorine in spite of similar color
removal.
When analyzing changes of other characteristic values, the "depth" of
chlorination is seen very distinctly at the use of a bigger chlorine dose.
After a 15 min chlorination period of dyeing wastewater previously irradiated,
the following effects were obtained:
Removal
effects
COD
BOD5
Detergents
Chlorine
50 mg/dm3
30%
50%
8%
dose
100 mg/dm3
32%
78%
55%
Another phenomenon worthy of noticing was that using chlorinated lime
without UV radiation catalysis, after 24 hours less color removal was obtained
than in catalyzed chlorination process after 15 minutes, but higher BOD^
removals were achieved reaching 85 percent and detergents equal to 57 percent.
The very small COD removal is surprising, being within the limit of determi-
nation error.
Since the chlorination of wastewater with chlorine water gave good color
removal in 15 minutes of contact time, a comparison was carried out to
determine the influence of UV light for the mentioned period of time but for
various chlorine doses. For the chlorination process without catalysis, the
49
-------
CZA« KONTAKTU Z
CMLOWNfcTKJN T.
100
so «o
ZUZI-m OAWKA CMUMtU
CONSUMED
kl) • 0,1 [X] X1tia
2*} X ft * TVI *CIKKI FARBIAKSMB
^J * °'° L*J OVUM* WA*r«vmTtH«
Rys 26. Zaleznodd efekt6w usuniqcia barwy ze iciek6w farbiarskich od
zuzytej dawki chloru przy zastosowaniu wody chlorowej.
Figure 26. Relationship between color removal and chlorine consumed in
dyeing wastewaters chlorination process using chlorine water
as an oxidizer-
50
-------
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-p
w
X
fH
• OS
X -P
O Oj
•H O
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ed
• H -P
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S >
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c
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nJ i
rH
13 W
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Oj ID
-P X
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h MH
rt o
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ce o
•H -H
O -P
G -H
t/3 O
l?
-P X
-------
dose of 50 mg of Cl^/dm^ was used while for the catalyzed process - 20 mg of
Cl2/dm3.
From the comparison shown below, it can be noted that when the chlorin-
ation was catalyzed, the COD was reduced by 24 percent in comparison with no
COD removal in the not catalyzed process.
CHLORINATION WITH CHLORINE WATER
•7
Dose, mg/dm0
Catalysis
Reaction time, min
Cl2 consumption, %
pH
Removal effects, % of
- color
- COD
- BODs
- Detergents
20
UV
15
79
3.5
97
24
66
60
50
without
15
62
3.5
97
0
77
55
In the chlorination process, a considerable decrease of pH takes place
down to the value of about 3.2. Wastewater neutralization after chlorination,
with lime, does not cause any changes in the color removal.
High doses of chlorine gave effective color removal from 0.5 percent dyeing
wastewater (Fig. 26). For the higher doses of 100 and 120 mg/dm3, practically
complete color removal was obtained reaching 99 percent. Lower consumption of
chlorine, as it could result from the increase of dyeing wastewater concen-
tration, is characteristic. At chlorine consumption in the range from 54 to
77 percent, the chlorine use was only 3.5 times higher than for wastewater 5
times more concentrated.
Conduction of the effective wastewater decolorization by chlorination
requires a certain amount of excessive free chlorine present in wastewater.
When using a constant chlorine dose of 50 mg/dm3 and a changeable contact time,
only 83 percent of color removal was possible. Such effect was obtained after
30 min contact and extending this time had no influence on decolorization and
concentration of the remaining chlorine at the level of 10 mg/dm3. Therefore,
a stability point of oxidation reaction can be considered.
When conducting the chlorination process on 0.5 percent dyeing wastewater,
UV radiation neither accelerated nor increased color removal, contrary to the
results obtained for 0.1 percent wastewater.
This phenomenon was probably connected with a too low concentration of free
radicals generated from the ultraviolet light in relation to a relatively high
concentration of pollutants contained in wastewater. At the same time, the con-
centration of these radicals was being decreased by a strong inhibitor of radi-
cal reaction, namely oxygen, which was generated in the decomposition reaction
52
-------
of hypochlorous acid. The decomposition of HOC1 is accelerated considerably
by UV radiation.
When conducting the chlorination process on lime coagulated wastewater,
the chlorination process causes further decrease of dyes concentration in the
wastewater. See Fig. 28. However, the earlier decrease of wastewater pH to
the value close to pH = 7 is very important. At wastewater saturation with
C09, the precipitation of calcium carbonate takes place causing certain
additional reduction of color (Fig. 28).
At the same time one can suppose that wastewater chlorination at pH
value close to neutral causes higher use of chlorine for dyes structure
decomposition, while in the case of alkaline reaction part of the chlorine
reacts with calcium ions, and the general rate of the chlorine reaction with
dyes is distinctly decelerated.
Color removal obtained jointly in a composite treatment process, which
consists of coagulation, neutralization, and chlorination, was higher than
these obtained in the individual processes. However, use of the above men-
tioned composite process only for color removal from wastewater seems techni-
cally unjustified. But in the case of wastewater treatment, the neutraliza-
tion of wastewater is necessary before their discharge into surface water.
Then the coagulation process with CaO and neutralization will be reasonable.
Similarly, if for sanitary reasons wastewater chlorination will be required
as the last stage of wastewater treatment, then the whole described techno-
logical train is fully justified.
During wastewater treatment process containing - coagulation - neutrali-
zation - chlorination - clarification - certain COD removal also takes place.
However, the removal effects are not too high and reach about 20 percent.
Chlorination process with relatively small doses of chlorine, but with
a long contact time caused color removal and change of color. Visually red
color turns to orange and finally to yellow (straw-yellow). During chromato-
graphic analysis with blotting paper, the distinct trace concentration of
dyeing substances was observed in wastewater visually almost decolored in
chlorination process.
From an analyzed sample, a zone of 188 ranr strongly colored blue-purple
was obtained using an anion exchange blotting paper. After the chlorination
process, wastewater decolored to a maximum gave on the same type of blotting
paper a weakly colored light yellow zone of 95 mm^. These light colors may
be the remaining original components or products of chemical changes of
different chromosome groups.
Changes in dyes structure caused by chlorination of 0.1 percent solution
of dyeing wastewater were also recorded in a thin-layered analysis. Chromato-
graphic thin layered analyses were carried out with silica gel in a solvent of;
pyridine:ammonia:water (1.3:1:1). The obtained results for untreated waste-
water were the following:
53
-------
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o 6
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54
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Rf. 100 99 purple band
95 orange band
89 purple band
87 yellow fluorescence in UV light
76 purple band
74 red-purple band
71 violet-purple band
68 red band
After chlorination, wastewaters decolorized to weak yellow tint showed
distinct green-yellow fluorescence in ultraviolet light. In chromatograms
the band colors were considerably less intensive, while in ultraviolet light
series of bands of distinct fluorescence appeared:
Rf. 100 Band color Fluorescence
99 yellow
95 »
92 blue
87 yellow
83 orange
82 weak purple
80 - violet
79 red
76 - yellow
74 brown-yellow
71 - yellow
In order to achieve full information of the character of reactions that
take place, spectrographic analyses were done in the ultraviolet and visible
ranges as well as in infrared range.
The UV-Vis spectra for 0.1 percnet wastewater undergoing chlorination
process during 15 minutes with the use of chlorine water of chlorine concen-
tration from 2-50 mg/dm3 show gradual decreasing of the band intensity in a
visible range as the color decayed. When the dose of chlorine was 30 mg/dm3,
the color of the sample changed from red to light yellow, and the spectra
show complete decay of the band in a visible range.
Examples of spectra that were obtained after chlorination at chlorine
concentrations of 2, 10 and 50 mg/dm3 are shown in Fig. 29. In UV range a
reduction of 286 nm and 206 nm bands was observed, but a strong absorption at
235 nm indicates an absorption of remaining aromatic structures. Under
influence of 20 mg/dm3 dose of chlorine and various exposition periods, one
could follow the changes occurring within the exposition period corresponding
to color transformation from red to orange. Considerable reduction in color
intensity that was observed after 5 minutes of chlorination was maintained at
the same level during subsequent reaction run for 180 minutes (Fig. 30).
The spectra in Fig. 30 shows a hypochromic effect in the visible range
band as well as hypsochromic shift that may be a result of influence of more
ionized reaction medium or by substitution.
55
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Rys 29. Widma 0.1% ^ciek6w farbiarskich po 15 rainutach chlorowania
dawkami/ I. 2 mg/dm3 chloru
II. 10 mg/dm3 chloru
III. 50 mg/dm3 chloru
Figure 29. Spectra of 0.1% dyeing wastewaters after 15 minutes of
chlorination applying. I. 2 mg/dm3 of chlorine
II. 10 mg/dm3 of chlorine
III. 50 mg/dm3 of chlorine
56
-------
0;5
0,2
330 *«> "KIO Sfo 650
OtUGO*t FAll - WAVE LEHSTH [
Rys 30. Widma 0.1% ^ciekdw farbiarskich.
0 - przed i po chlorowaniu przez
a - 5 rainut - dawka chloru 20 rag/dm3
b - 180 minut dawka chloru 20 mg/dm^
Figure 30. Spectra of 0,1% dyeing wastewaters.
0 - untreated
a - after 5 minutes chlorination applying 20 rag/dm*
b - 180 minutes chlorination applying 20 mg/dm^
57
-------
The spectra recorded from 0.5 percent wastewater chlorinated with a
chlorine dose of 50 rag/dm^ showed similarly a hypochromic effect in the band
of visible range increasing with chlorine action, and also hypsochromic effect.
Moreover, a transitional absorption band appeared at about 370 nm, declining
when the orange color was being transformed to yellow (Fig. 31).
In IR spectra obtained after 50, 75, and 100 minute chlorination, the
following changes appeared: decay of nitrile band, considerable reduction in
3400 cm-1 band intensity, and an almost complete decay of alkane bands in the
range of 2975 - 2840 cm-1. A different new band appeared with increasing
intensity according to the time of chlorination (Fig. 32). The maximum of the
band is in the range of 3200 - 3100 cm-*. The changes suggest a shift of
alkane bands influenced by arising electronegative groups. This may be chlorine
in the form of chlorinated derivative, or oxygen connected with carbon adjacent
to alkane group. However, the shift is greater that those published in the
literature for such effects. Since decreasing intensity of 3400 cm-1 band Is I
observed, one can assume that there are reactions occurring at the same time
within amine groups.
The kind of the reaction is undeterminable using the spectrum. One can
only pay attention to occurrence of bands in the absorption range of oximes.
At lower frequencies a decay of the 1580 - 1570 cm-1 band is observed, a new
broad band appears with maximum at 1665 cm-1, which is likely to be related to
the structural elements: C=0,C=N, N=0.
Decay of the 1420 - 1410 and 870 cm-1 bands was observed. These bands
are attributed to carbonate ions. As the chlorination period was prolonged,
the intensity of the new 1400 cm-1 band increased and the band at 1380 cm-1
declined. In "finger print region" reduction of absorption in the band at
1100 - 1000 cm-1 occurred, but no significant changes are found in the band
of 1200 - 1100 cm-1.
5 . 4 BROMINATION
Methods and Range of Investigations
Bromine as an oxidant has been used for decolorization of wastewater
generated in pharmaceutical industry. According to the literature, bromine
was not used for textile wastewater treatment.
In the framework of presently reported work, the bromination process was
carried out by dosage of bromine water into wastewater containing 0.1 and
0.5 percent solutions of dyeing wastewater. Various contact times from 1
minute to 24 hours of various various bromine doses from 5 to 200 mg/dm^S were
used.
Bromine water used for the investigations was prepared by dissolving
bromine in water, so that it contained from 12.5 to 16.5 g/dnH of free
The laboratory investigations were carried on at a temperature of 20 °C
and with continuous sample mixing. Remaining bromine was determined by iodo
metric method. Wastewater treatment effects were defined on the basis of
such indices as color, COD, BOD5, radioactive detergents and pH.
58
-------
IttO
460
610
aeo
490
380
540
FAU ' WAVE LCMGTH [
Rys 31. Widma 0.5% SciekAw farbiarskich. 0 - przed chlorowaniem;
a, b, c_,- po chlorowaniu dawk^ 50 mg/dm^ do zmiany zabarwienia
na pomaraficzowe; d - j.w. do zabarwienia foltego.
Figure 31. Spectra of 0.5% dyeing wastewaters. 0 - untreated and after
chlorination applying 50 rng/dm^ of chlorine until changing
of purple hue to a, b, c, - orange, d - yellow.
59
-------
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Discussion of the Investigations Results
Color removal from dyeing wastewater by the bromination process occurs
at a high rate. Decolorization takes place almost immediately after mixing
of wastewater sample with bromine water.
When the testing of the bromination effect at a dose of 40 mg/dm3 of Br2
for 0.1 percent solution of dyeing wastewater with contact time of 1, 3, 5,
10, 15, 30, 60, 120, 180 minutes and 24 hours, the permanent effect of color
removal obtained is shown in Fig. 33.
However at the same time, the level of bromine use increased as contact
time increased. For 0.1 percent solution of dyeing wastewater, the level of
bromine use changed from 51 to 74 percent. For 0.5 percent solution of dyeing
wastewater, this level changed from 67 to 98 percent. The increasing bromine
use together with contact time was caused probably by bromine evaporation to
environment during sample mixing, and with partial bromine consumption in
other reactions running at a lower rate or causing deeper destruction of dyes.
This thesis was partially confirmed by the results of COD, BOD^, and
anionic detergents for 0.1 percent solution of wastewater at a contact time
of 1 and 30 minutes and for a constant bromine dose of 40 mg/dm3 of Br2-
REMOVAL EFFECT
COD
BOD5
Detergents
1 Min.
5.3%
12.9%
60.0%
30 Min.
15.9%
17.0%
67.0%
The degree of color removal fundamentally depended on the appropriate
dose of bromine. At the same time the bromine use level decreases as the
provided dose of bromine increases for the given contact time.
When using a constant reaction time of 5 minutes in case of 0.1 percent
solution of dyeing wastewater and various doses of bromine ranging from 5 to
200 mg/dm3 of Br2, the bromine use level obtained was in the range from 100
to 24 percent. At the same time as the bromine dose increased, the color
removal effect was increasing, too, in a given case, from 20 to 100 percent
CFig. 34).
When using a constant reaction time of 5 minutes in case of 0.5 percent
solution of dyeing wastewater and various doses of bromine in the range from
5 to 500 rag/dm3 of Br2, the bromine used level obtained was in the range from
100 to 49 percent. As the bromine dose increased, the color removal was also
increasing in the range from 11 to 95 percent (Fig. 34).
The maximum value of color removal effect was obtained at the dose of
200 mg/dm3 of Br2
61
-------
«Of
90
99
80
9 30
CM* KOMTAK** Z tmOtHUH
_ DAWHA
Rys 33. Zalezno^d efektdw usuniqcia barwy ze ^ciekfcw farbiarskich
od czasu kontaktu z bromem
Figure 33. Relationship between color removal and bromination time in
dyeing wastewaters bromination process
62
-------
CZA3 KONTAKTU Z BKOMKM
•NOMINATION TlMC
9O
«O
450 2OO
ZUZYTA tNMVKA VltOMU
WIOMIMC COM*U*»D
2SO
Rys 34. Zalezno^tf efektiw usuni^cia barwy ze ^ciekiw farbiarskich
od zuzytej dawki bromu.
Figure 34. Relationship between color removal and bromine consumed in
dyeing wastewaters bromination process-
63
-------
During the investigations, the characteristic partial color removal of
untreated wastewater was turning from red color through orange into yellow.
These changes evidence transformations that take place in dyes chromophore
groups.
The paper chromatography on anionic blotting paper showed a change of
zone of strong blue-purple tint of a surface equal to 188 mm2 into a zone of
intensive yellow color of a surface area of 74 mm2. In this zone a more
condensed zone could be distinguished of a surface of 42 mm2.
Changes in dyes structure resulting from their bromination were clearly
visualized in thin-layer chromatographic analysis. As it was earlier reported,
such analyses were carried out with silica gel in the composition: pyridine:
ammoniarwater in the proportions: 1.3:1:1.
A sample decolored with bromine water to orange tint showed yellow-green
fluorescence in UV light, as shown below:
Rf. 100 Band color Fluorescence
(97) - yellow
(91) - blue
89 orange-yellow
87 yellow
83 brown
80 (80) brown yellow
(78) - yellow
76 brown
(74) - yellow
A sample decolored at a maximum degree to pale-yellow tint showed green
fluorescence, and the appropriate data were:
Rf. 100 Band color Fluorescence
(99) - blue
(93) - yellow
91 orange-brown
(89) - yellow
87 brown
84 brown
78 brown
( )Fluorescence spots
The decay of many chromatographic bands in comparison to the chromatogram
of untreated wastewater solution given in chapter 5.3 is very characteristic.
Many orange-yellow bands appeared and particularly brown ones. These are
probably due to dyes in solution, namely welan or sulfur dye. The found brown
bands would indicate generation of different chromophore groups. The arising
of many fluorescence bands results probably from changes of function groups
after oxidation or substitution with bromine.
64
-------
When analyzing spectra after wastewater oxidation with bromine water in
IR band, the changes were similar to chlorination. Slight variations were
only observed between chlorinated and brominated wastewater spectra within
the "fingerprint range."
UV-Vis spectra show the following changes: after bromination process
the absorption band shifted from 540 nm to 510-500 nm. Hypsochromic shift
was accompanied by considerable hypochromic effect.
New bands were produced at the same time .at 440 nm and 395 nm (Fig. 35).
Sample color changed to orange, orange-yellow and yellow. The spectrum of
pale yellow sample showed decay of bands in visible range. In UV-range
hypsochromic effects occurred as well as the increased absorption in the
shortest wave length band (Fig. 36).
Both in chlorination and bromination processes, the changes in observed
spectra indicated changes in functional groups determining a type of chromo-
phoring system and functions of auxochromes. Strong absorption in the ultra-
biolet range and negligible spectral changes in this range indicate conserva-
tion of aromatic structures in wastewaters after color removal.
5.5 ADSORPTION
Methods and Investigations Range
The investigations were carried out with the use of powdered activated
carbon Carbopol WS, granulated carbon Z^ of 1-3 mm granulation and bentonite
Nobel. Selection of the appropriate kind of activated carbon was made based
on the analysis of qualitative characteristics of home-made activated carbons.
In order to enable the transfer of data characterizing the adsorption process
in static conditions to practical conditions, tests were accomplished of
adsorption process in dynamic conditions (5,6,7).
The tests of adsorption process were divided into two parts. The first
one included laboratory tests made in order to determine the adsorption capa-
city of the tested activated carbon and Nobel bentonite in static conditions.
Tests were made for the individual 7 solutions of dyes baths and also for
1 percent mixture of these baths. Physical and chemical constitution of
tested solutions of dye baths and their mixture are given in Table 2.
Tests were also carried out for different concentrations of dyeing waste-
water consisting of a mixture of 4 selected dyeing baths and assistants, the
composition of which is given in Table 1.
The second part included tests of adsorption process carried on continu-
ously in adsorption columns with expanded bed of granulated carbon Z..
Laboratory investigations on continuous wastewater flow through adsorp-
tion column were carried out for 0.05 and 0.1 percent dyeing waster and
assistants (Table 1). Laboratory tests of adsorption process were carried on
with determination of the optimum time of reaction between wastewater and
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Rys 35. Widma 0.5% sciekdw farbiarskich-
a - przed i po bromowaniu
b - do zmiany barwy purpurowej na pomaranczowa
c - zotto-pomarariczowa,
d - blado zoJrta
Figure 35. Spectra of 0.5% dyeing wastewaters*
a - untreated and after bromination
b - until changing of purple hue to orange
c - yellow-orange
d - pale yellow
66
-------
100
Rys 36. Widma ^ciekow farbiarskich
a -.przed, i po bromowaniu
b - do zmiany barwy purpurowej na pomaranczowa,
c - i zolta,
Figure 36. Spectra of dyeing wastewaters
a - untreated and after treatment with bromine
b - until changing of purple hue to orange
c - to yellow
67
-------
sorbent at the fixed temperature of 20 °C and the optimum dose of sorbent.
The obtained values were the basis for determination of adsorption isotherm.
Based on the obtained adsorption isotherm, the equilibrium adsorption capacity
was defined for the given activated carbon and bentonite in reference to the
tested solutions of dyeing baths and their mixtures. The adsorption capacity
was then determined graphically as the ordinate for abscissa value = log Co
presented in COD milligrams and dye milligrams for gram of activated carbon
or bentonite.
Adsorption columns used in the investigations carried on in dynamic
conditions were made from glass pipes with a diameter of 30 mm and 1500 mm
high with a conical bottom ended with a supply conduit. The adsorption bed
was hung on a metal net. Columns were filled with activated carbon Z4 of
1-3 mm granulation. The height of adsorption bed was of about 900 mm, after
scarification the height was about 1200 mm.
The technological system consisted of 2 columns in series. After
exhausting the system, the first column was disconnected, the second column
became the first one, and a column with new filling was set up as a second
one. The adsorption columns were run as expanded beds, i.e., wastewater was
applied from the bottom of the column.
Analytical checking of the adsorption process in dynamic conditions
included determination of the following indices: pH, basicity, COD, color,
anionic detergents.
Samples for the above mentioned determinations were taken during the
whole period of adsorption columns studies at intervals of 15 to 30 minutes.
Using the obtained results, relation curves were drawn of concentration of
tested pollution indices in wastewater flowing out, and total volume of waste-
water, which flow through the column in a given time period. From the obtained
relations, a "puncture" time was defined for the bed of the second column, and
a time of adsorption capacity exhausting for the first column. The adsorption
capacity of a sorbent in dynamic conditions was calculated.
Tests in dynamic conditions were accomplished for the following load of
adsorption bed:
Dyeing wastewater 0.1%
- 4.67; 6.23; 9.58; and 15.58 tn3/m2
Dyeing wastewater 0.05%
- 20.0
Discussion of the Investigations Results
The equilibrium adsorption capacities defined on the basis of test
investigations for powdered activated carbon Carbopol WS, and bentonite Nobel
expressed in rag of COD, and mg of dye for gram of sorbent have been presented
in Fig. 37 and 38.
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Rys 38. PorAwnanie warto^ci pojemnosci adsorpcyjnych badanego wegla
aktywnego cws oraz bentonitu nobel wyznaczonych w odniesieniu do
roztwor6w wodnych kapieli barwiarskich i ich mieszaniny.
Figure 38. Equilibrium adsorption capacity of cws powdered activated carbon
and nobel bentonite estimated for tested dyeing baths and their
mixture.
70
-------
Optimum effects of the adsorption process in static conditions obtained
for selected solutions of dyeing baths and their mixtures of 1 percent concen-
tration are presented in Table 8.
The obtained values of equilibrium capacity varied within a wide range,,
depending on the type of dye. The tested activated carbon showed the highest
adsorptive capacity in case of sulfur, metallized, dispersed and direct dyes.
Lower values were obtained for chrome and basic dyes.
The lowest value was obtained in case of reactive dyes. The adsorptive
capacity of the activated carbon at 1 percent mixture of tested dyes was equal
to 270 mg of COD/g.
When comparing the efficiency of color and COD removal obtained at opti-
mum operational parameters of adsorption process, it was found that among two
tested sorbents, only the activated carbon gave positive effects for all tested
solutions of dye baths, while the bentonite had a significant adsorptive capa-
city only in case of the basic dye.
When considering the obtained adsorption rates for the individual dyes,
the basic and sulfur dyes are very difficult to be adsorbed by activated
carbon. It is apparent in the decreased efficiency of color and COD removal
which after 30 minutes contact with adsorbent reach respectively 70.0 percent
and 67.7 percent for basic dyes and 50.0 and 47.8 percent for sulfur dyes.
Extending the adsorption time did not improve the efficiency of the process.
For the remaining dyes, the efficiencies of adsorption process were high,
and after 60 minutes of contact time there was 90 to 99.8 percent color
removal and 71 to 91 percent for COD (Table 8).
The decrease in efficiency of adsorption for dye baths in case of basic
and sulfur dyes is likely due to molecule structure of these dyes and their
ability to dissociate.
The tests were carried out for 0.1, 0.5 and 3.0 percent solutions of
dyeing wastewater (Table 1), and the results obtained from these experiments
are summarized in Fig. 39 and Table 9.
The adsorption process was carried out using powdered activated carbon
Carbopol WS and for 0.1 percent dyeing wastewater. Additional tests were
accomplished with granular activated carbon Z* which was later used in the
investigations with continuous columns.
The adsorption in steady conditions was accomplished at natural pH and
pH of 12, and adsorption process began immediately when pH about 12 was
reached. The contact time of wastewater with NaOH solution applied for pH
adjustment was 1-3 minutes.
From the obtained results, it can be stated that the adsorption process
at original pH gives higher efficiency of color and COD removal in comparison
with the efficiency of adsorption process at pH of about 12.
71
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72
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100
0
0
0,2
0,6 0,8
PAWKA W^GLA [g/dm
DOSE OF ACTIVATED CARBON
©
0.1%
^CIEKI
DYEING
SCIEKI
DYEING
SCIEKI
DYEING
SCIEKl
DYEING
FARBIARSKIE
WASTEWATERS
FARBIARSKIE
WASTEWATERS
FARBIARSKIE
WASTEWATERS
FARBIARSKIE
WASTEWATERS
WITHOUT pH ADJUSTMENT
pH-v!2
WITHOUT pH ADJUSTED TO 12
WITHOUT
pH-12
WITHOUT
pH ADJUSTMENT
pH ADJUSTED TO 12
Rys 39. Pordwnanie efektAw usuniecia barwy w procesie adsorpcji na
pylistym w^glu aktywnym cws dla rt&znych wartosci pH.
Figure 39. Color removal by powdered activated carbon adsorption effect
of pH adjustment to 12.
73
-------
TABLE 9. ADSORPTION OF DYEING WASTEWATER BY ACTIVATED
CARBON CARBOPOL WS - BASED ON JAR TESTS
Concentration
of dyeing
wastewaters
%
0.1
0.1
0.1
0.5
0.5
3.0
Dosage of
activated
carbon
e/dm3
0.3
0.3
1.0
l.oxx
3.0
0.5
1.0
0.5
1.0
2.0
6.0
Time
adsorption
min
45
45
45
60
60
45
45
45
45
45
30
PH
7.20
-12
-12
7.64
8.72
7.62
7.80
-12
-12
-12
8.0
Colorx
removal
%
82
38xxx
61xxx
67
85
68
83
30xxx
44XXX
60xxx
83.5
COD
removal
%
40
43xxx
54xxx
13
37
39
40
18xxx
30xxx
33xxx
40
x Comparison method
xx Granular activated carbon
xxx
results have been estimated based on initial values of COD and color
of wastewaters after pH adjustment to 12
74
-------
Total efficiency of color reduction at pH 12 for tested wastewater con-
centrations of 0.1 and 0.5 reached about 50 percent of effects obtained in
the adsorption process at original pH (Fig. 39).
The plotted isotherms of pollution adsorption expressed in terms of the
COD indicate, that a large amount of substances, which are not adsorbed by
tested activated carbon, is present in the effluent.
The obtained straight plots intersect the adscissa (log concentrations
of adsorbed substances), not indicating any point on the ordinate. Fig. 40
is an example of adsorption isotherms for dyeing wastewater of 0.5 percent
concentration.
When considering the color as a parameter of dyeing wastewater pollution,
the shape of adsorption isotherms obtained provided an evaluation of the
equilibrium capacity of tested carbon. Depending on dyeing wastewater con-
centration, the equilibrium capacities in terms of carbon Carbopol WS were
as follows: from 958 percent of color for 0.1 percent wastewater, 331 per-
cent of color for 0.5 percent wastewater to 32 percent of color for 3.0 per-
cent dyeing wastewater.
For the laboratory tests on the continuous adsorption columns, dyeing
wastewater of 0.05 percent and 0.1 percent concentration were chosen. The
process was carried out at the original pH at room temperature using granular
activated carbon Z% for which the determined equilibrium capacity expressed
in terms of COD was equal to 5 mg COD/g.
The obtained results of color removal gave the basis for selection of
surface loading for further laboratory investigations.
For the laboratory investigations carried on for two columns linked in
series, the surface loadings selected were: 9.58 rn-^/rn^ for 0.1 percent waste-
water and 20.0 nrVm^ for 0.05 percent wastewater.
The conditions and the results for the two columns linked in series were
as follows:
0.1% dyeing wastewater:
- average flow rate of wastewater through columns - 6.9
- average surface loading - 9.58 m^/m^.h 3' 1 W^/fr^
- time of contact of wastewater with adsorbent in entire system -
10 min (calculated for non-filled working space of column)
- COD of wastewater before adsorption - 45 mg 02/dm^
- residual COD in effluent after adsorption - average 15 mg/dm3, range
from 10 to 20 mg 02/dm3. Critical concentration of breakthrough was
20 mg 02/dm3 COD.
- efficiency of color removal in total system - 80%
- efficiency of COD removal in total system - 55-78%, 66% in average
- an average adsorption capacity of total system - 3.0 mg COD/g
- services time of system before the break point - 4.5 hours
75
-------
COLOUR 9
iO IgC 2.2
• BAftWA - COLOUR
O ChZT - COD
Rys 40. Izoterma procesu adsorpcji na pylistym w^glu aktywnym
carbopol ws. £>cieki farbiarskie - 0.5% proces prowadzony
dla pH naturalnego-
Figure 40. Adsorption isotherm on powdered activated carbon - carbopol ws
for 0.5% dyeing wastewaters without pH adjustment*
76
-------
0.05% dyeing wastewater:
- average flow rate of wastewater through column - 14.4 dm^/h
- average surface loading - 20 m3/m2.h
- time of contact of wastewater with adsorbent in entire system -
5 minutes (calculated for non-filled working space of column)
- COD of wastewater before adsorption - 25 mg C^/drn^
- COD of wastewater remaining after adsorption - average 5 mg
range to 16 mg/dm^. Critical concentration for which breakpoint
was defined - 16 mg/dnr
- efficiency of color removal in total system - 98-100%
- efficiency of COD removal in total system - 80%
- an average adsorption capacity of total system - 4 mg COD/g
- service time of system before breakpoint - 4 hours
If the color removal values were applied to evaluate efficiency of
the adsorption process in continuous columns instead of COD values, the
service time would be extended twice.
Substantial decrease of the indispensable dose of adsorbent can be
obtained by earlier introduction of the coagulation process. The comparison
of the obtained efficiencies of color removal in the adsorption process with-
out wastewater coagulation and after coagulation with 6000 mg CaO/dm^, 250 mg
Al2CS04)3/dm3 and 500 mg FeS04/dm3 was presented in Fig. 41.
77
-------
n
5!
_
» 3
DAWKA W3QLA
DOSC OP ACTIVATED CARBON
UNTRCATCO OYKIPNt vrASTCWATCRS
OCZYSzCZONK WST^PHIV MCTOOA, KOAGULAC9I
TACATCD MY COO CO**MJLATlON P«iOR TO AO%O««*TIOH
AtlBKI PARAtARSKlC OCTrflKCZONC WST^PHIS MCTOOA, KOAfiULAOf Z U*rciC*
DYKlNO WASTCWATCRS TRCATCO BY AljfSO^ COAQULATIOH PR KM TO ADSORPTION
PAABIAttSKK OCZYSZCZONK
WASTKWATCR* TltSATEO
MCTOOA, KOAOULAOl X ur*OCM
COAOULATION HRiO« TO
Rys 41. Por6wnanie efektiw usuniocia barwy w procesie adsorpcji 3%
^ciekow farbiarskich na pylistym wQglu aktywnym
Figure 41. Color removal by powdered activated carbon adsorption 3% dyeing
wastewaters effect of varying activated carbon doses
78
-------
SECTION 6
BIOLOGICAL METHODS FOR DYEING WASTEWATER TREATMENT
6.1 THE ACTIVATED SLUDGE METHOD
Methodology and the Scope of Studies
The studies on dyeing wastewater treatment were carried out in three
stages. In the first stage some testing runs were done using the lab-scale
units, periodically loaded with municipal wastewater with addition of some
selected substances typical for dyeing wastewater. In the first series,
laboratory investigations used continuous feeding with municipal wastewater
blended with six selected substances specific for dyeing wastewater. In
these investigations, an aeration tank of 5.7 dm3 capacity was used.
The second series of investigations with continuous wastewater feeding
was carried out with municipal wastewater containing 0.1 volume percent of a
mixture of selected dye baths and assistants (Table 1).
The studies dealt with a wide range of concentrations of the applied
substances to get as much as possible explicit information about their effect
on the biochemical processes.
The batch tests were performed using seven laboratory scale aeration
tanks with activated sludge, periodically fed with wastewater.
Six wastewater mixtures and a reference sample were applied to the tests.
The wastewater mixtures were composed from raw municipal wastewater and
the following additives: reactive dye - Lunasol Rot 5B, basic dye - Aniline
BLN, sulfuric dye - Sulfuric Brown, welan dye - Welan Brown, assistant -
fixing agent WOM, assistant-dispersing agent NNO. Each of them was at a con-
centration of 300 mg/dm^.
The initial activated sludge was obtained from the municipal wastewater
treatment plant. Before the studies began the sludge was first acclimated
for four days to a mixture of municipal wastewater containing 0.1 volume
percent of dyeing wastewater. To achieve an increased load of activated
sludge, the test investigations were carried out with raw municipal wastewater,
The laboratory models used for these studies were of 3 dm^ capacity, and
the initial volume of the mixed liquor (culture) was of 1.5 dm3. The initial
content of activated sludge suspended solids was about 1.0 g/dm^. Activated
79
-------
sludge loadings in terms of BOD^ and COD in g/g MLVSS-d for particular acti-
vated sludge cultures were as follows:
BODc
COD COD
Not filtered Filtered
1. Municipal wastewater
2. Municipal wastewater
with addition of
reactive dye
3. Municipal wastewater
with addition of
basic dye
4. Municipal wastewater
with addition of
sulfuric dye
5. Municipal wastewater
with addition of
weIan dye
6. Municipal wastewater
with addition of
fixing agent WGM
7. Municipal wastewater
with addition of
dispersing agent NNO
0.084 - 0.160 0.150 - 0.358 0.061 - 0.290
0.102 - 0.185 0.300 - 0.705 0.282 - 0.583
0.052 - 0.156 0.360 - 0.890 0.290 - 0.530
0.047 - 0.155 0.240 - 0.462 0.116 - 0.356
0.061 - 0.158 0.429 - 0.954 0.384 - 0.754
0.0236 - 0.067 0.270 - 0.454 0.171 - 0.315
0.074 - 0.148 0.220 - 0.732 0.220 - 0.547
Discussion of the Results
The pollution concentration of municipal wastewater varied during the
course of investigations. The average values of BODs and COD of the pro-
portioned wastewater were respectively about 90 mg/dm^ and 117 rag/dm^.
Simultaneously, significant fluctuations in BODg values reaching a mean value
of 40 mg/dm^ were noted. Much lower fluctuations were observed in the case
of COD of treated wastewater. The major part of the results varied in the
range from 40 to 43 mg/dm^. The pollution removal from wastewater during the
control tank processing was about 56 percent and 65 percent, respectively for
BOD5 and COD.
A decrease in the mixed liquor suspended solids content in the aeration
tanks was observed during the studies. The decrease was from the initial
value of about 800 rag/dm-* (volatile parts) to about 480 mg/dm3. The only
exception was for the tank fed municipal wastewater with addition of fixing
agent WOM. Simultaneously a decrease of activated sludge volume index from
about 170 cm^/g to 128 cm-Vg Was observed.
80
-------
An explicit determination of the inhibiting influence of dyes or assist-
ants on the activated sludge process appears to be difficult based on the
obtained results, however it was apparent that the dye addition to municipal
wastewater disturbed the process.
The analysis of 8005 and COD removal effect from the municipal wastewater
mixed with dyes and/or assistants gave very interesting results. It revealed
that the addition of reactive dye and dispersing agent NNO caused an increase
in BODtj of about 50 mg/dm5. Simultaneously a twice or three times increase
in COD of filtered samples was observed for each case. A significant BODr
reduction in a range from 50 percent to 80 percent was noted for all tested
series. The gained COD removal effects ranged from 10 to 35 percent. Com-
paring the absolute amounts of removed pollution loads expressed in BODg and
COD, it can be stated that both biochemical, as well as the chemical oxygen
demand, have been similarly reduced.
Discussion on the Results of Laboratory Studies Using A Continuous Wastewater
Feeding System
The tested wastewater mixture used for the series of tests with continu-
ous feeding was characterized by relatively high BODr and COD values. The
average BOD^ values in the first series were about 145 rag/dm^; whereas in the
second series, the BODr values increased to about 210 mg/dm^. Simultaneously,
there was not such a significant difference in COD values in the both described
test series. The average COD values for the filtrated samples in the first
series were of about 253 mg/dm^ and for the second series 235 mg/dm^.
The Figures 42 - 45 show that the variability of COD and BODr values was
rather significant.
In the subsequent series of technological investigations, the following
operational parameters were used:
The average pollution concentrations in crude and treated wastewater as
well as the treatment effects are listed below:
1st Series
Parameter
BOD5 not
filtered
COD not
filtered
COD filtered
Total suspended
solids
Suspended solids
volatile parts
Inflow
mg/dm
145
435
253
175
128
Outflow
mg/dm5
52
299
183
140
98
Treatment
Effect
%
64
31
28
20
24
Inflow
mg/dm5
210
415
235
163
110
2nd Series
Outflow
mg/dm5
40
150
80
70
50
Treatment
Effect
%
81
64
66
57
55
81
-------
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ZOO
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PROCENT SXUMULOWAKY
99
WV6T^PD«ttN(A
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AvrRMUT VftLUI O^t
BOD5-
52[mgO2/dm3]
Rys 42. Cz^stotliwo^d wyst^powania warto^ci bzt5 w ^ciekach doplywajacych
I odplywajacych z komory napowietrzania. Seria I.
Figure 42. Frequency of BOD5 unfiltered. Series I.
82
-------
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^o so to so to TO so go 95
PROCENT »KUMUUOW*Hy
5REDMIA WARTO9C nCDIALNA :
VALUES OF:
DOPtYW
O atfuj
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COD
09
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Rys 43. Czqstotliwo^d wystepowania warto^ci chzt w ^ciekach dopiywajacych
i odplywaj^cych z komory napowietrzania. Seria I.
Figure 43. Frequency of influent COD and effluent COD. Series I.
83
-------
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S I
M O
CD
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0 IL
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ID
Rys 44. Cz^stotliwoid wystqpowania warto^ci BZT5 w dciekach doplyw^jacych
i odplywaja.cych z komory napowietrzania. Seria II-
Figure 44. Frequency of influent, effluent BOD5- Series II.
84
-------
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The operating parameters for activated sludge process used to obtain the
above data were as follows:
Time of wastewater aeration
with activated sludge h
Sedimentation time in a
secondary settling tank h
The loading of activated
sludge volatile parts by
BOD5 load g/g-d
The loading of activated
sludge volatile parts by
COD not filtered g/g-d
The loading of activated
sludge volatile parts by
COD filtered g/g-d
1st Series
6.5
2.2
0.23 - 1.04
0.70 - 3.35
0.42 - 2.82
2nd Series
7.0 and 11.5
2.8 and 4.5
0.14 - 0.52
0.18 - 0.91
0.08 - 0.61
The contents of activated sludge in an aeration tank:
1st Series
g/dm3 1.82 - 0.30
Total suspended solids
Suspended solids -
volatile parts
Average concentration of
suspended solids -
volatile parts
g/dm:
g/dm*
1.43 - 0.22
1.01
2nd Series
1.65 - 2.80
1.10 - 2.23
1.83
Despite the differences in wastewater concentrations in both series, the
test results are listed and discussed together.
For simplification, because of the uncontrolled fluctuation in concen-
tration of the fed substrate and volatile parts of suspended solids of acti-
vated sludge in aeration tanks, the above mentioned series have been divided
into several intervals. In the 1st series two intervals and in the 2nd series
eight intervals have been distinguished.
The average BOD5 and COD values for a filtered sample, the activated
sludge suspended solids, and the wastewater retention time in aeration tank
for the particular distinguished intervals were determined. The determined
average values were applied to the calculation of the dyeing wastewater
86
-------
treatment efficiency index. The average values for the first series of con-
tinuous testing are presented in Table 10. For the second series of testing,
the average values are listed in two tables, i.e., 11 and 12.
A comparability of the first and second series results has been compared
by analyzing the BOD^ and COD reduction efficiency versus the pollution
loading (Fig. 46).
A reduction of BOD^ in the range from 60 percent to 90 percent was
reached by the pollution loading of values from 0.2 to 0.95 g/g-d.
Presenting the obtained results as a dependence of the activated sludge
efficiency (W = k-S) from the loading (L), there exists a possibility (Fig. 47)
to comprise all results by applying the following general mathematical
expression:
W = 2
2.2 + L
where W = efficiency in D~l
L = sludge loading in g/g-d
Using the same method, the comparable COD (filtered sample) results for
the first and second continuous testing series have been obtained. However,
it must be noticed a low reduction efficiency of COD (Fig. 46) for loadings
extending over 1.0 g/g-d. This efficiency was in the range from 20 percent
to 30 percent. It also appeared that the chlorination process of the biologi-
cally treated wastewater did not lead to a significant increase of the COD
removal effects. However, in two cases a 40 percent and 47 percent removal
of unfiltered sample COD by the presence of 50 and 60 mg/dm-5 doses of chlorine
was observed, while the COD removal for filtered sample was only about 12 per-
cent,
The above presented facts may relate to the difficult biochemical regener-
ation and incomplete chemical aeration of the added dyes and assistants.
The wastewater treatment through the activated sludge process has not
resulted in the color removal. In general, the color was unchanged except
for the sporadical instances in both series when about 20 percent of color
removal was attained. The other investigations reveal that the color reduc-
tion can be effectively obtained in the chlorination process of biologically
treated wastewater.
Applying a chlorine dose of 34 mg/dm^ concentration, a complete decolori-
zation can be obtained (Fig. 48). The complete decolorization can be obtained
by using the adsorption process on activated carbon, as well. A complete
removal of the fine suspended matter on a sand filter is required before
applying the above mentioned adsorption method. The sand filtration leads
also to a COD and BOD^ removal.
87
-------
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Rys 47. Wydatek osadu czynnego^
Figure 47. Efficiency of activated sludge process
92
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Czaschlorpwama
Ch Ion nation time
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60
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7
10
30
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ZUTYTA DAWKA CMLORU - lftrr?~\
CHUJRtNE CONSUMED L^S/0 J
Rys 48. Efekt usuniqcia barwy w zalezno^ci od zuzytej dawki chloru w
procesie chlorowania ^ciekiw farbiarskich 0.1%, uprzednio
oczyszczonych metoda, osadu czynnego^
Figure 48. Relationship between color removal and chlorine consumed in
chlorination process of 0.1% dyeing wastewaters treated by
activated sludge method.
93
-------
No correlation was found between the measured oxygen uptake rates by
activated sludge and the COD and BODs removal effects.
A relatively constant oxygen uptake in a range of 0.21 to 0.29 g 02/g-d
was observed for loadings ranging from 0,2 to 0.95 g/g-d.
The phosphates content in the treated wastewater became stabilized at a
markedly high level, i.e., 18 mg/dm3. After the treatment, a significant
phosphates content decrease of about 50 percent was noted. This likely can
be explained by the phosphates conversion into complex compounds.
An explicit reduction of the anion detergents as a result of wastewater
treatment has also been observed. If the initial detergents concentration
was of about 12 mg/dm3, after treatment the concentration decreased to
1.7 mg/dm3 which is an 86 percent detergent removal.
In analyzing the nitrogen compounds changes, it was noted that in the
first testing series, the ammonia nitrogen average content oscillated between
15 mg/dm3 to 20 mg/dm3. These were rather low concentrations, however because
of the 6005: N ratio, it is of some importance. The lack of substantial differ-
ences in ammonia nitrogen concentrations, due to the wastewater treatment, was
a distinctive conclusion from these investigations (Fig. 49).
Similarly, in the second testing series, the ammonia nitrogen concentra-
tions did not vary significantly. If in the supplied crude wastewater the
ammonia nitrogen concentration varied in the range of 15 to 35 mg/dm3, the
similar increased concentration level was observed in the treated wastewater
(Fig. 49).
The inhibition of the nitrification process was additionally proved by
the analysis of nitrite and nitrate nitrogen concentration changes. No signif-
icant changes in the above mentioned compounds concentrations were determined
as a result of the applied treatment method. Although the tested pollution
loadings, namely 0.20 to 0.95 mg/g.d, were sufficiently high to inhibit the
intensive growth of nitrification microorganisms, at the lower loadings at
least the initiation of nitrification process might be expected.
The phenols concentration in the tested wastewater was equal to 0.7 mg/dm3
The process of wastewater treatment was found to be effective for phenol
removal, as was expected. The phenol concentration in the effluent discharged
from the secondary settling tank was of about 0.016 mg/dm3, thus 98 percent of
phenol was removed.
The tested wastewater contained heavy metals derived from dyes. The
following changes in heavy metals concentrations in wastewater were found:
Cu influent 0.003 - 0.005 mg/dm3
effluent 0.004 - 0.010 mg/dm3
t
Zn influent 0.007 - 0.027 mg/dm3
effluent 0.004 - 0.006 mg/dm3
94
-------
0 \
60
20
o
series
o
o
o
DNi
OATS
1974
o DOPtYW - INFLUENT
• ODP-tYW - EFFLUENT
Rys 49. Zmiany zawarto^ci azotu amonowego w procesie osadu czynnego
Figure 49. Ammonia nitrogen changes in the activated sludge process.
95
-------
Cr influent 0.005 - 0.015 mg/dm3
effluent 0.002 - 0.014 rag/dm3
Pb influent 0.018 - 0.036 mg/dm3
effluent 0.021 - 0.023 mg/dm3
Recapitulating the investigation results of wastewater treatment by the
activated sludge method, it can be ascertained that this method is entirely
useful. The activated sludge process enables efficient organic matter removal
However, this process does not effectively remove the color. The best color
removal was not better than 30 percent.
6.2 THE ANAEROBIC DIGESTION OF WASTEWATER
Methodology and the Scope of Studies
A mixture of the municipal wastewater and digested sludge was basically
applied in the test investigations.
The seven wastewater mixtures, described previously in the chapter on
activated sludge process, have been applied.
The tests were conducted in the three sequential series:
1st series employed: 20 cm3 dose of mixture - daily discharged and
and fed; 7-day detention time.
Ilnd series employed: 20 cm3 dose of given mixture - daily fed;
7-day detention time.
Illrd series consisted in the digestion without wastewater dosage;
7-day detention time.
The studies were accomplished by use of units of 200 ml mixed liquor
volume. The initial mixed liquor for the 1st series was combined from 75 per-
cent by volume of wastewater and 25 percent by volume of digested sludge.
The digester final effluent obtained in the 1st series was used as feed
material for the Ilnd series. Consequently, the final effluent from the Ilnd
series was utilized as feed material in the Illrd series.
The temperature of the process was 32 °C
o,-,
The analytical control of the wastewater anaerobic digestion process
involved the measurements of the quantity of gas, the pH value, the alkalinity,
and the ammonia nitrogen concentration in the samples taken from the sludge
digestion chamber after 7, 14 and 21 days.
Discussion of the Results
The investigation results indicated a relatively low ability of the tested
wastewater to digestion. The quantity of gas produced in the course of the
three series ranged in the limit of the measurement error. The systematic
96
-------
drop in pH and alkalinity of wastewater during the digestion indicates an
acid fermentation process. The pH and alkalinity changes in wastewater during
the digestion process are shown in Figures 50 and 51.
A reduction in COD and color values of 10-19 percent and 4-10 percent,
respectively, were obtained during the digestion process of wastewater
employing the 7-day detention time.
Methodology and the Scope of Studies
The studies were carried out using two anaerobic bed units of different
size. In the initial phase of studies, an anaerobic filter of 7.0 cm diame-
ter and 180 cm height was used. The filter was filled with gravel of 2.5 to
3.5 cm graining. The total capacity of the filter was of 6.93 dm3, and the
empty space (not filled with gravel) was of 3.30 dm3 capacity.
In the next phase of studies, a column of 14 cm in diameter and 250 cm
in height was used.
The total volume of the anaerobic bed was of 38.5 dm3, and the active
volume of the bed was of 16.0 dm3. The treated wastes under anaerobic condi-
tions were then delivered to the aeration tank of the activated sludge pro-
cess. The diagram of the applied experimental units is shown in Fig. 52.
The wastewater discharged by the anaerobic bed passed a tee unit in which
a separation of the fermentation gas from the wastewater took place. The
wastewater flowed off to a collecting vessel or to the next aerobic treatment
phase. Whereas the gas was collected in a graduated glass tube displacing the
wastewater from it.
The anaerobic bed unit must be blacked out when the unit is constructed
from a transparent material, i.e., metalplex.
The municipal wastewater with an addition of active dye Lunasol Rot 5B
in the amount of 150 mg/dm3 was the substrate used. An intensive red color
was the feature of this mixture. In the second part of the studies, a 0.1
percent solution of dye bath on a municipal wastewater basis was used.
The Treatment Efficiency in Anaerobic Conditions
Despite the low concentrations of wastewater led to the anaerobic bed
and subsequently short detention time of wastewater, very good removal of the
organic matter was achieved. A 58 percent COD removal was obtained from a
composition of municipal wastewater and the active dye of 310 mg/dm3 COD con-
centration and at 3.5 day detention time. It should be emphasized that the
anaerobic bed loading was only 0.089 kg COD/m^.d. See Fig. 53.
For a much less loading of 0.035 kg COD/m3.d caused by a lower concen-
tration of wastewater mixture and a longer detention time, the obtained
removal of COD was on'ly about 30 percent (.Fig. 54).
97
-------
CZA« PEKNENTACJI
DBTVHTtON TIME
Iff
• PMOOA
KBAICTYWY
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Rys 50. Zmizny pH w procesie beztlenowej fermentacji 5ciekAw miejskich
z dodatkiem wybranych barwnikow
Figure 50. Changes of pH values in the anaerobic treatment process of
municipal wastewaters with addition of selected dyes
98
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ao _
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Plt£>BA KONTROLNA
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Rys 51. Zmiana zasadowo^ci ^ciek
-------
1-DOPtYW
INFLUENT
2-ZtOZE BEZTLENOWE
ANAEROBIC BED
3-KOMORA NAPOWIETRZANIA
AERATION TANK
Rys 52. Schemat urza/izen dosViadczalnych.
Figure 52. Laboratory equipment used for continuous studies on anaerobic
and aerobic wastewaters treatment-
100
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Rys 53. Efektywno^d usuni^cia ChZT przy obcig,zeniu zioza tadunkiem
0.089 kg/mS-d.
Figure 53. Efficiency of COD removal at the organic load of anaerobic
bed equalled to 0.089 kg/m3-d-
101
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Rys 54. Efektywno^i usuniecia ChZT przy obci^zeniu zloza aradunkiem
0.035 kg/m3-d
Figure 54. Efficiency of COD removal at the organic load of anaerobic bed
equalled to 0.035 kg/m3-d.
102
-------
An analysis of the other parameters of wastewater digestion process
revealed a probability of a toxic interaction of active dye.
Similar COD removals were obtained in further studies with application
of 0.1 percent dyeing wastewater solutions and at a lower load. For the waste-
water mixture with a COD in a range of only 150-160 mg/dm3 and at 8.42 day
detention time in an anaerobic bed, the bed loading was 0.018 kg COD/m3-d.
At such low bed loading, a 31 percent and 17 percent COD removal were obtained.
See Fig. 55.
The proceeding efficiency of wastewater methane fermentation became
explicit when observing the increase in ammonia nitrogen concentrations. The
ammonia nitrogen concentration, in the wastewater introduced to the anaerobic
bed was 29 mg/dm3, while in the wastewater after treating on the bed, the
ammonia nitrogen concentration increased to about 50 mg/dm3 (Fig. 56). The
increase was not a result of a change in the mineral nitrogen form,, namely
of a reduction of the oxidizable nitrogen form, but a consequence of biochemi-
cal degradation of organic substances. The organic nitrogen released from the
organic matter could cause such significant increase in ammonia nitrogen con-
centration.
Subsequently with the ammonia nitrogen concentration increase, an increase
in alkalinity of wastewater during the digestion process was observed. An
average increase from 4.9 to 7.6 me/dm3 were noted. The alkalinity changes
in wastewater under anaerobic conditions and at a given testing period are
presented in Fig. 57.
An unexpected removal intensification of COD was gained when increasing
the hydraulic load to 0.256 m3/m3-d, and hence increasing the COD load to
0.0346 g/dm3-d as well as shortening the wastewater detention time to 3.90
days. The average COD removal determined from a filtered sample was 42 per-
cent and 55 percent from the unfiltered sample treating the wastewater at the
mentioned parameters (Fig. 55).
For the municipal wastewater of a higher concentration of organic sub-
stances, the anaerobic filter loading was 0.0556 g/dm3-d, and the obtained
COD removal efficiency was 34 percent for a filtered sample and 42 percent
for unfiltered sample.
From the investigations carried out so far, a direct relationship between
the wastewater treatment efficiency at anaerobic conditions and the hydraulic
loading or pollution load was not found.
Considerable color removal was the most significant effect of anaerobic
bed application to the textile wastewater treatment. The fresh discharge
from the anaerobic bed was sometimes colorless or most often slightly colored
and clear. Although in the contact with the air, it became turbid and gradu-
ally pink, but the final color intensity was far from the primary one. The
process of the partial color reversion clearly appeared during the subsequent
wastewater treatment using the activated sludge. Therefore, it seems to be
reasonable to discuss the color removal effect from both the biological treat-
ment stage aspects, i.e., anaerobic bed treating and the activated sludge
103
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Rys 56. Zmiany azotu araonowego w procesie fermentacji
Figure 56. Changes o£ ammonia nitrogen in the anaerobic wastewater treatment
40
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Rys 57. Zmiany zasadowo^ci ^ciekAw w procesie ich fermentacji•
Figure 57. Changes of alkalinity in the anaerobic wastewater treatment
105
-------
treating. Based on the investigation results, it can be stated that the acti-
vated sludge treatment method gives a 14 percent to 30 percent color reduction
in the treated wastewater. The anaerobic bed application enabled a color
reduction in the range of 49 percent to 82 percent, depending on the investi-
gation period and the bed COD loading used. Figure 58 presents the results
of the studies on color changes resulting from the two-stage process of bio-
logical treatment. The changes in color removal in correlation with the
applied pollution loads can be approximately determined (Fig. 59}. However,
the relationship is not complete because it does not include the loading
variations of the activated sludge. The existing suggestions, that the loading
variability of activated sludge can be neglected, required a confirmation in
the further studies. The main purpose of these studies was to prove the
possibility of the partial chemical conversion of the complex organic sub-
stances during the anaerobic process. In the aerobic conditions, the organic
substances are stabilized. The experience from these studies suggests that
greater attention must be paid to the abilities and the usefulness of anaero-
bic processes in the wastewater treatment.
The dyeing wastewater treatment using only the activated sludge process
produced an insignificant and sporadic color removal.
The above observations were confirmed by spectroscopic measurements in
the visible and ultraviolet range using a UV-Vis Pye-Unicam 1800 model spectro-
photometer with a spectrum recorder. The spectra were recorded in the full
range or in a chosen range. Spectra examples of the crude and treated with
sludge wastewater are presented in Fig. 60. These spectra performed during
different periods of technological investigations revealed a lack of any
conversions in the form of the investigated compounds. The different back-
ground values are merely due to the light diffusion caused by the presence
of different suspended solids amounts or colloidal substances in the crude or
treated wastewater.
The color intensity was decreased by blending the dyeing bath and assist-
ants with municipal wastewater. The dark color characteristic for such a mix-
ture became changed with elapse of time. On the presented spectra, a point
of inflection is observed at the 570-ran band. The resulting spectra changes
due to the 5-days wastewater storage are shown in Fig. 61. A hypsochromatic
shift of the absorption maximum appeared as well. A flocky sediment settling
from the mixture of dyeing bath and municipal wastewater was observed. It
can be suggested that a sorption phenomenon of dyes occurred on the organic
suspended solids. However, the low rate of this phenomenon hints a more com-
plex mechanism. It can be supposed as well that during the organic wastewater
detention in the presence of bacterial microflora, biochemical and chemical
processes take place. The biochemical processes were probably anaerobic. Sub-
sequently, the suspended solids precipitation could result from the colloid
stability shifting, as well as the carbonates forming in consequence of the
solution pH value change.
The previously reported removal of color on the anaerobic bed prove that
the course of phenomenon is of a biochemical mechanism. A spectrum of a
strong adsorption band of range from 200-220 nm and a deflection point in
2/0 nm, was obtained for the dyeing wastewater solution on the influent to the
106
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1-DOPtYW
INFLUENT
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430 590 750
Dl.UGO$£ FALI
WAVE LENGTH
910
Rys 60. Widma spektroskopowe ^ciek6w przed i po oczyszczaniu osadem
czynnym-
Figure 60. Spectra of the untreated and activated sludge treated wastewaters
108
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PR0.BKA JWIEZA
FRESH SAMPLE
PRfiBKA PO 5 DO-
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-WYWANIU
'SAMPLE AFTER
5 DAYS STORAGE
390 430 470 510 550 590 630 670
DUJGOSd FALI nm
WAVE LENGTH
Rys 61. Zmiany widma 3ciek6w w wyniku ich przechowywania•
Figure 61. Changes "in wastewater spectra as a result of wastewater storage
109
-------
bed A strong and wide adsorption band in the visible range of an adsorption
maximum in 530 run was seen also. The recorded spectrum for a solution diluted
in the rate of 1:2.5, shown in Fig. 62, has a maximum in the 205 nm band. A
similar spectrum shown in Fig. 63 has its maximum in the 206-220 nm band. The
difference in the band of maximum location was likely the consequence of the
differences between the municipal wastewater samples used.
The deflection point on the recorded spectra at the increased sensitivity
(Fig. 64) or at the fourfold extended adsorption layer in a 4 cm cell appeared
at the 410 nm band.
The fresh discharge from the anaerobic bed was transparent or very
slightly colored and clear, but when stored in contact with the air, it became
turbid and gradually pink colored; however, the final coloring changed little
in comparison to the primary coloring. The spectra reveal a decrease in
absorption maximum in the 530 nm (Fig. 62). In the ultraviolet range, there
appears a second absorption maximum in the 350 nm band or a deflection point
in the same band (Fig- 63).
In order to explain the color reversion phenomenon, the fresh discharge
from the anaerobic bed was oxidized by use of the hydrogen peroxide solution.
A momentaneous coloring increase was observed, which suggests that under an-
aerobic conditions a reduction occurs, producing a transient decolorizing.
The oxidization results in a slight hypsochromic shifting of the absorption
maximum.
The activated sludge process in the second degree of treating, as was
earlier mentioned, leads to a further color removal, in contrary to the
separate application of the activated sludge treating method.
The differences between discharges from the anaerobic bed and the acti-
vated sludge tank become very apparent under the action of perchloric acid,
which is shown in Fig. 65. The total and permanent decay of color appeared
in the discharge from the tank, and the turbidity occurred in the discharge
from the filter.
The color removal effect in a two-stage dyeing wastewater treatment was
relatively high and the average equaled 75 percent (Fig. 66). Consequently,
the two-stage treatment process application enabled the efficient removal of
organic wastes expressed in terms of BOD, and COD. In the first treatment
stage, a 37 percent COD removal, referred to the filtered samples, was gained.
The joint COD removal in the two stages was of about 80 percent (Fig. 67).
The changes in the other parameters expressed in concentrations are also
presented in the same figure.
110
-------
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4.0
0.8 -
0,6 -
0,4 -
IMFLUENT
2 -
EPPUIBNT FUOM TMC AHASIKWIC aep
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ofcuaofcd FALI r -I
(.morn l nmj
Rys 62. Zmiany widma ^ciekfew w dwustopniowym procesie oczyszczania.
Figure 62. Changes in wastewater spectra in the anaerobic-aerobic wastewater
treatment process.
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Rys 64. Wycinek widma 4ciek6w biologicznie oczyszczonych, przy
zwiQkszonej czuio^ci.
Figure 64. Changes in spectra in visible range of wastewaters due to the
biological method of treatment.
113
-------
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- OOPWW Z HOMO** OSADU
aCOOMOAIIY KFFLUEMT PftOM TK
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Rys 65. Zraiana widma ^ciek6w poddanych dziataniu kwasu nadchlorowego w
zalezno^ci od stopnia ich oczyszczania'
Figure 65. Changes in wastewater spectra due to the biological method of
treatment-effect of HC10- addition to the treated wastewater.
114
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0 Z-tOZE BEZTLENOWE
EFFLUENT FROM THE ANAEROBIC BED
ZtOZE BEZTLENOWE + OSAD CZYNNY
Y ANAEROBIC 8ED
Rys 66. Efekty usuni^cia barwy w dwustopniowym procesie oczyszczania
Figure 66. Color removal by the anaerobic and aerobic wastewater treatment
process^
115
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SECTION 7
THE INFLUENCE OF THE SELECTED CONTAMINANTS
ON THE ANAEROBIC DIGESTION OF SLUDGE
The Scope and Methodology of Studies
The dye and assistants concentrations studied for the influence on the
methane production are listed in Tables 13 and 4.
The investigations used laboratory digestion tanks of 610 cm3 total
capacity and a 400 cm3 sludge volume. The digestion process was carried out
at the constant sludge volume and at the temperature of 32 °C without sludge
feeding. The digestion controls included the daily measurement of gas and
the physical and chemical analysis of sludge. The data were taken after 0,
10, 20,, and 41 or 45 days of digestion.
The physical and chemical analyses were carried out by the commonly
accepted methods. The fatty acids contents in the oversludge liquid were
determined by use of the gas chromatograph applying the Pye-Unicam Model 105
chromatograph. The separation was done in a column fed with 5 percent
"F.F.A.P." phase settled on 101 chromosorp. The detection was conducted by
use of a flame-ionizing detector. The chromatogram assessment was performed
by comparing the chromatograms with fatty acids standard solutions, i.e., the
acetic, propionic, butyric, isovaleric, and valeric acids.
The sludge mixture containing 60 percent by volume of primary settling
tanks sludge and 40 percent by volume of digested sludges from the municipal
wastewater treatment plants was the initial material for the studies.
The initial material contained from 26.7 to 38.8 g/cm3 solid residue, and
the volatile parts contents in sludge varied from 62 percent to 67.5 percent.
The effect of the added substances on the sludge anaerobic digestion was
evaluated by comparison of the produced quantity of gas, and physical and
chemical analysis results of sludges for the tested and reference samples.
The Results of Studies
The investigation results enabled the determination of the concentration
of the tested substances which inhibit the gas production in the digestion
process. The results are shown in Figures 68 to 73.
The rate of the daily gas production in relationship with the concen-
trations of the chosen substances in sludges is shown'in Figures 74 to 76.
117
-------
TABLE 13. CONCENTRATION RANGE OF THE TESTED SUBSTANCES
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14
Type of dye or
assistant
Active dye:
lunasol rot 5B
Dispersed dye:
synthetic yellow
Basic dye:
aniline red BL
Metal complex dye:
polfalon green 2BL
Direct dye:
helion yellow
Acid dye:
folan red B
folan red G
Chrome dye:
chrome red B
Sulfuric dye:
sulfur brown
Wei an dye:
we Ian brown
Half-wool dye:
strong red PGL
Assistant:
fixing agent WOM
Assistant:
dispersing agent NNO
Assistant:
elanofor
Dyeing bath mixturex
Series
Number
III
III
III
III
II
III
II
III
II
III
II
III
II
II
III
II
III
II
II
Concentration, g/dm^
0.3 1.0 3.0
0.3 1.0 3.0
0.3 1.0 3.0
0.3 1.0 3.0
0.3 1.0 10.0
3.0 6.0
0.3 1.0 10.0
3.0 6.0
0.3 1.0 10.0
3.0 6.0
0.3 1.0 10.0
3.0 6.0
0.3 1.0 10.0
0.3 1.0 10.0
3.0 6.0
0.3 1.0 10.0
3.0 6.0
0.3 1.0 10.0
0.3 1.0 10.0
0.3% 1.0% 5%
xContent is given in Table 4
118
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Rys 68. Produk.cja gazu w procesie beztlenowej fermentacji osad6w,
Figure 68. Gas production in the anaerobic sludge digestion.
119
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Rys 69. Produkcja gazu w procesie beztlenowej fermentacji osaddw-
Figure 69. Gas production in the anaerobic sludge digestion.
120
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Rys 70. Produkcja gazu w procesie beztlenowej fermentacji osaddw.
Figure 70. Gas production in the anaerobic sludge digestion.
121
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Rys 71. Produkcja gazu w procesie beztlenowej fermentacji osadAw.
Figure 71. Gas production in the anaerobic sludge digestion.
122
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Rys 72. Produkcja gazu w procesie beztlenowej fermentacji osaddw-
Figure 72. Gas production in the anaerobic sludge digestion
123
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Rys 73. Wpfyw stQzen barwnikAw i srodk6w pomocniczych na produkcjq,
gazu w procesie beztlenowej fermentacji osaddw.
Figure 73. Gas production in the anaerobic sludge digestion effect of
dyes and assistants concentration.
124
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Figure 74. Gas production rate in the anaerobic sludge digestion.
125
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Figure 75. Gas production rate in the anaerobic sludge digestion.
126
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Rys 76. Szybko^d produkoji gazu w procesie beztlenowej fermentacji osadiw.
Figure 76. Gas production rate in the anaerobic sludge digestion-
127
-------
This rate presents the influence of the tested substances on the digestion
process.
Fig. 77 shows the concentrations of the free volatile fatty acids after
about 10, 20, and 45 days of sludge digestion, containing an addition of
separate dyes and assistants.
The investigations revealed that the 300 mg/dm3 concentration of separate
dyes in sludges did not appreciably affect the sludge methane digestion process.
The gas production in conversion on 1 g of the sludge solid mass after 41 days
digestion was about 10 percent reduced in relation to the reference samples.
The samples containing an addition of reactivated dispersed dyes indicated
an exceptional reduction of 14 percent and 20 percent.
A decreased gas production was observed at the initial period of digestion
for some dyes, namely the dispersed, basic and welan dyes. The pH value and
alkalinity of the oversludge liquid did not indicate disturbances in the
digestion proceeding. The sludge analysis done after 45 days of digestion
revealed a loss of volatile parts of about 25 percent to 40 percent. The
digestion degree of sludges was about 23 percent to 42 percent, where the
lowest degree related to the sludges with the metal complex and welan dyes
addition.
The volatile fatty acids content in the oversludge liquid approximated
the content in reference samples after 20 days digestion. The 1.0 g/dm3 con-
centration of the following dyes: metal complex, active, basic, dispersed
and welan, caused considerable disturbances in the digestion process. The
gas produced per 1 g of solid mass of sludge after 41 days of digestion
decreased significantly and in relation to the reference sample reduced by
about 38, 56, 65, 66, and 71 percent for the particular samples. A decrease
of volatile parts was observed when the gas production was reduced. In the
oversludge liquid samples containing basic and welan dyes, an increase of
fatty acids concentration to 620 mg/dm3 and 1980 mg/dm3 after 45 days was
found. In the case of welan dye, after 20 days of digestion there was an
increase of fatty acids to 1630 mg/dm3, whereas after the same digestion period
the concentration in reference sample was of 50 mg/dm3.
The sludge digestion degree was low, i.e., from 15 percent to 18 percent
when for the reference sludges it was about 30 percent. The sludges after
digesting were characterized by poor dewatering which was expressed in an
increased filter resistant coefficient.
The other dyes, i.e., the chrome dye, the direct dye, the acid dye, the
sulfur dye, and the half-wool dye, all of 1.0 g/dm concentration did not
inhibit the digestion process. Only in the case of the sulfur dye a decreased
gas production in the initial digestion process was found. Significant pH
values and alkalinity changes have not been observed in the oversludge liquid,
and the content of free volatile fatty acids after 45 days digestion was simi-
lar to the reference samples, being of 50 to 100 mg/dm3.
128
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Rys.77. StQzenie sumaryczne wolnych lotnych kwas6w tluszczowych w
procesie beztlenowej fermentacji osadAw ^ciekowych zawieraj^cych
barwniki i ^rodki pomocnicze.
Figure 77. Summary concentration of free volatile fatty acids in the
anaerobic digestion process of sludge containing tested dyes
and assistants.
PART I
129
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barwniki i ^rodki pomocnicze.
Figure 77. Summary concentration of free volatile fatty acids in the
anaerobic digestion process of sludge containing tested dyes
and assistants.
PART II
130
-------
The gas production after 41 days of digestion referring to the 1 g of
sludge solid mass was reduced from 10 percent to 13 percent.
At the 3.0 g/dm3 content of dyes, an inhibition of sludge digestion pro-
cess was observed. It relates to the sludges containing the active, basic,
dispersed, acid and half-wool dyes. The gas production after 41 days of
digestion, referring to the 1 g of sludge solid mass, was respectively reduced
as follows: 78, 70, 85, 88, 56, and 53 percent.
A rather low sludge digestion rate, ranging from 6 percent to 13 percent,
was noted, except for the sludge with half-wool dye addition for which the
digestion degree was of about 22 percent. Generally, an increase in the
volatile fatty acids concentrations in the oversludge liquid of samples con-
taining the above mentioned dyes was found during the digestion. The 3.0 g/
dm3 concentration of chrome, sulfur and direct acids did not inhibit the
digestion.
The gas production, as well as the quantity of removed volatile parts,
were approximately the values obtained for the reference samples.
<7
When these dyes concentration were increased to 6.0 g/dm , the reduction
of gas production was of 24, 72 and 37 percent.
The maximum concentrations of dyes and assistants existing separately in
sludges at which the digestion process was not disturbed, were determined as
follows during the studies:
Active dye 0.3 g/dm3
Dispersed dye 0.3 g/dm3
Basic dye 0.3 g/dm3
Metalcomplex dye 0.3 g/dm'
Welan dye 0.3 g/dm3
Acid dye 1.0 g/dm3
Half-wool dye 1.0 g/dm3
Direct dye 3.0 g/dm3
Sulfuric dye 3.0 g/dm3
Chrome dye 6.0 g/dm3
Elanofor - assistant 0.3 g/dm3
Fixing agent - assistant 1.0 g/dm5
Dispersing agent -
assistant 1.0 g/dm3
The higher concentrations of the investigated dyes equal to 10.0 g/dm3
almost entirely inhibited the sludge digestion process. A significant
accumulation of fatty acids was observed in the sludge samples after about
45 days digestion, except the sample containing the direct dye for which the
reduction of gas production was 37 percent after 41 days of digestion. In the
oversludge liquid of the mentioned sample, the lowest content of fatty acids
equaled to 300 mg/dm3.
131
-------
From all the tested assistants, the elanofor revealed the most undesirable
influence on the digestion process. A concentration of 1.0 g/dm3 caused an
80 percent reduction of gas production.
The analysis of oversludge liquid, after 45 days digestion, indicated
a pH and alkalinity decrease, and a reasonable accumulation of fatty acids.
The presence of dispersing agent NNO in sludges in concentrations of 0.3 g/dm3
and 1.0 g/dm3 did not inhibit the digestion process, but 10.0 g/dm3 concen-
tration of it reduced the gas production by 54 percent.
A significant increase in volatile fatty acids concentrations has been
observed in the oversludge liquid. An inhibiting effect of the fixing agent
WOM on the digesting process occurred at the 3.0 g/dm3 concentration causing
a reduction of gas production by about 70 percent.
The 0.3 percent and 1.0 percent solutions of dyeing bath mixture in
sludges did not have an inhibiting effect on the digestion process, as
expressed mainly in the quantity of the produced gas.
An adverse influence of 5 percent solution of dyeing bath in sludges on
the methane digestion process was noted, however the concentrations of
particular sludge mixture components were lower than the concentrations which
in the separate samples did not inhibit the digestion process.
Comparing the obtained results for the particular contaminants and for the
mixture, it can be concluded that there exists a synergistic effect of compo-
nents in the multicomponent mixtures. It can be then expected that the dyeing
wastewater, even at low concentrations, may inhibit the methane sludge diges-
tion process at an undesirable quality composition.
132
-------
REFERENCES
1. Zuckerman, M. M., and Molof, A. H. "High Quality Reuse Water by Chemical-
Physical Wastewater Treatment." Jour. Water Poll. Control Fed.^ 42, 437
(1970).
2. Mulbarger, M. C., Grossman, E., Dean, R. B., and Grant, 0. C. "Lime
Clarification, Recovery, Reuse and Sludge Dewatering Characteristics."
Jour. Water Poll. Control Fed., 41, 2070 (1969).
3. Reichertet, U., and Sentheimer, H. "Untersuchungen zur Anwendung von
Ozone bei der Wasser und Abwasserreinigung." (Use of Ozone in Water and
Wastewater Purification.) Vom Wasser, 41, 369 (1973).
4. Murphy, K. L., Zaloum, R., and Fulford, D. " Effect of Chlorination
Practice on Soluble Organics." Water Res., 9_, 389 (1975).
5. Bunch, R. L. " Advanced Wastewater Treatment - Physical-Chemical Treatment."
Prepared for the NATO Committee on the Challenges of Modern Society,
September 1975.
6. Ford, D. L. "Current State of the Art of Activated Carbon Treatment/'
Presentation at the Open Forum on Management of Petroleum Refinery
Wastewater. Tulsa, Oklahoma, January 26-29, 1976.
133
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-79-160
3. RECIPIENT'S ACCESSIOWNO.
4. TITLE AND SUBTITLE
"DEVELOPMENT OF METHODS AND TECHNIQUES FOR FINAL
TREATMENT OF COMBINED MUNICIPAL AND TEXTILE WASTEWATER
INCLUDING SLUDGE UTILIZATION AND DISPOSAL"
5. REPORT DATE
December 1979 (Issuing Datel
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Jan Suschka
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Environmental Pollution Abatement Center
Research Institute of Environment Development
Katowice, Poland
10. PROGRAM ELEMENT NO.
PL-480
11. CONTRACT/GRANT NO.
PR5-532-2
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory--Cin. ,OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Project Officer: Robert L. Bunch (513)684-7655
16. ABSTRACT
The investigations were carried out on laboratory scale, employing various
mixtures of dyeing and municipal wastewaters. The processes studied were:
coagulation, ozonization, chlorination, activated carbon, activated sludge, and
anaerobic digestion.
The most widely used dye from each class of dyes was chosen for determining
adsorption isotherms. The results showed that activated carbon is quite selective
and cannot be used to treat some dye wastes. Activated carbon was found to be
particularly efficient in final treatment of dyeing wastewaters. Activated sludge
and anaerobic digestion, while effective in removing BOD constituents, were not
effective in removing color. Many of the dyes were inhibitory to digestors.
Lime appeared to be the best coagulation agent. Feasibility of lime reclamation
by recalcining the sludge and recycling the lime in the coagulation process was
demonstrated.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTlFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Sludge disposal
Waste treatment
Industrial waste treatment
Wastewater
Activated carbon
Sludge
Textile waste
13B
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
146
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
134
«US GOVERNMENT PRINTING OFFICE: 1380-657-146/5558
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