SEPA
United States
Environmental Protection
Agency
Industrial Environmental Research EPA-600/7-78-181
Laboratory September 1978
Research Triangle Park NC 27711
Assessment of Coal
Conversion
Wastewaters:
Characterization and
Preliminary
Biotreatability
Interagency
Energy/Environment
R&D Program Report
-------
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EPA-600/7-78-181
September 1978
Assessment of Coal
Conversion Wastewaters:
Characterization and Preliminary
Biotreatability
by
P.C. Singer, F.K. Pfaender, J. Chinchilli,
A.F Maciorowski, J.C. Lamb III, and R. Goodman
University of North Carolina
Department of Environmental Sciences and Engineering
Chapel Hill, North Carolina 27514
Grant No. R804917
Program Element No. EHE623A
EPA Project Officer: T.W. Petrie
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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ABSTRACT
The objectives of this project are to assess the environmental
impact of wastewater contaminants originating from the production of
synthetic fuels from coal, and to evaluate, on a bench-scale, alternative
wastewater treatment technologies for the control of these contaminants.
This report presents the results of a survey aimed at determining the
chemical characteristics of coal conversion wastewaters and at identifying
specific organic contaminants which might be found in such wastewaters.
The constituents have been identified by reviewing the published literature,
visiting coal gasification and liquefaction research and development
installations, and analyzing reports and project documents from a variety
of coal conversion operations. A preliminary assessment of the aquatic
impact of these wastewaters and of their biological treatability is also
presented. The results indicate that approximately 60-80% of the total
organic carbon is phenolic in nature, consisting of monohydric phenols,
dihydric phenols, and polyphenols. The remainder of the organic
material consists of mono- and polycyclic nitrogen-containing aromatics,
oxygen- and sulfur-containing heterocyclics, polynuclear aromatic hydrocarbons,
and simple aliphatic acids. The composition of the wastewaters appears
to be relatively uniform, especially with respect to the phenolic constituents,
regardless of the specific process technology and type of feed coal
employed.
At the concentrations reported, the discharge of these wastewaters
would have an adverse impact on aquatic life and, as a result, a significant
degree of wastewater treatment is necessary. While aerobic biological
processes appear to be among the methods of choice for treating these
wastewaters, additional information is required in order to assess the
biological treatability of these coal conversion wastewaters and to
develop suitable design and operating guidelines. An experimental
program to provide such information is underway.
This report was submitted in partial fulfillment of Grant No.
R804917 by the Department of Environmental Sciences and Engineering of
the University of North Carolina at Chapel Hill under the sponsorship of
the U.S. Environmental Protection Agency. This report covers the period
November 1, 1976 to May 30, 1978.
ii
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CONTENTS
Abstract ii
Figures iv
Tables vi
Acknowledgements viii
1. Introduction 1
2. Conclusions 2
3. Background 3
4. Chemical Characteristics of Coal Conversion Wastewaters .... 7
5. Potential Aquatic Impact of Organic Constituents of
Coal Conversion Wastewaters 24
Aquatic Pollution Problems: General Considerations ... 24
Aquatic Toxicities of Organic Constituents of
Coal Conversion Effluents 26
Phenols 32
Aliphatic Acids 35
Polynuclear Aromatic Hydrocarbons 35
Nitrogen- and Sulfur-Containing Compounds ..... 39
Research Needs , 41
References 43
6. Microbial Degradation of Organic Constituents in
Coal Conversion Wastewaters 48
Literature Review 48
Phenol and Other Monoaromatic Hydrocarbons .... 48
Nitrogen-Containing Aromatic Compounds 69
Polynuclear Aromatic Hydrocarbons 77
Summary of Literature Findings 82
Experimental Biodegradability Studies:
Preliminary Screening 84
References 89
7. Preliminary Biotreatability Studies 93
Introduction 93
Objectives 93
Composition of Synthetic Coal Conversion Wastewaters . . 94
Pilot Units for Acclimation and Biotreatability 94
Studies 94
Experimental Approach 96
Respiration Studies 97
Future Directions 102
iii
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FIGURES
Number Page
1 Initial Reactions in the Bacterial Degradation
of Various Compounds that Converge on Catechol .... 50
2 Initial Reactions in the Bacterial Degradation of
Various Compounds that Converge on
Protocatechuate 51
3 Initial Reactions in the Bacterial Degradation of
Various Compounds that Converge on Gentisic Acid ... 52
4 Example of an Aromatic Compound Possessing an Alkyl
Side Chain which Remains Intact Prior to Ring
Cleavage 54
5 Ortho and Meta Fission Pathways for the Dissimilation
of Protocatechuate and Catechol 55
6 Bacterial Metabolism of Gentisic Acids 56
7 General Reaction Scheme for Bacterial Degradation of
Substituted Phenols 65
8a Oxidation of Dihydric Phenols 68
8b Oxidation of Cresols and Other Methylphenol
Derivatives 68
9 Pathway Proposed for the Microbial Degradation of
3,4-Dihydroxypyridine 71
10 Pathway Proposed for the Microbial Degradation of
2,5-Dihydroxypyridine 72
11 Pathway Proposed for the Degradation of Pyridine by
Nocardia sp 73
12 Pathway Proposed for the Microbial Degradation of
Pyridine by Bacillus sp 74
13 Pathway Proposed for the Microbial Degradation of
Indole 76
14 Pathway Proposed for the Degradation of Naphthalene by
a Species of Pseudomonas 78
15 Proposed Pathway for the Microbial Degradation of
Phenanthrene 80
iv
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FIGURES (continued)
Number Page
16 Proposed Pathway for the Microbial Degradation of
Anthracene 81
17 Formation of cis-Dihydrodiols from the Microbial
Metabolism of Benzo(a)pyrene and Benzo(a)anthracene . 83
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TABLES
Number Page
1 Water Quality Characteristics of Coal Conversion
Wastewaters 4
2 Mass Spectrometric Analysis of Benzene-Soluble Tar .... 5
3 By-Product Water Analysis from Synthane Gasification
of Various Coals .................... 8
4 Percentage of COD Attributable to Phenol in Synthane
Gasification
5 Some General Properties of Raw and Processed
Wastewater from the Lurgi-Process Plant at Sasolburg,
South Africa ...................... 10
6 Concentration of Organic Compounds in Raw and Processed
Wastewater from the Lurgi-Process Plant at Sasolburg,
South Africa ...................... 11
7 COD and TOC-Equivalents of Organic Constituents of
Sasol Wastewater .................... 12
8 Concentration of Organic Compounds, as COD and TOC,
Found in the Raw and Processed Wastewater from the
Lurgi-Process Plant at Sasolburg, South Africa ..... 13
9 Percentages of Unidentified COD and TOC in Sasol
Wastewater ....................... 14
10 Contaminants in Product Water from Synthane Gasification
of Various Coals .................... 15
11 Summary: Organic Constituents in Coal Conversion
Wastewaters ....................... 16
12 Polynuclear Aromatic Hydrocarbons in SRC Raw Process
Water .......................... 22
13 Summary of Environmental Behavior of Classes of Organic
Coal Conversion Effluent Constituents .......... 27
14 MATE and EPC Values in Water for Some Constituents of
Coal Conversion Wastewaters Based on Human Health
Considerations ..................... 28
15 MATE and EPC Values in Water for Some Constituents
of Coal Conversion Wastewaters Based on Ecological
Considerations ..................... 30
vi
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TABLES
Number Page
16 Definitions of Subcategories of Estimated
Permissible Concentrations (EPC's) ........... 31
17 Acute Toxicity of Some Phenols to Fish .......... 33
18 Threshold Concentrations of Various Phenolics to Lower
Aquatic Organisms ................... 34
19 Toxicities of Some Organic Acids to Aquatic Organisms . . 36
20 Toxicity of Some Polynuclear Aromatic Hydrocarbons to
Marine and Aquatic Organisms .............. 37
21 Toxicity of Some Nitrogen-Containing Compounds to
Aquatic Organisms ................... 40
22 Proposed Metabolic Pathways for the Microbial
Degradation of Selected Phenolic Compounds ....... 57
23 Oxidation and Removal of Various Phenolic Compounds
by Phenol-Acclimated Bacteria ............. 67
24 Initial Screening of Various Organic Compounds Found
in Coal Conversion Effluents .............. 85
25 Summary of Biodegradation Results for Compounds After
5 Days ......................... 88
26 Composition of Synthetic Coal Conversion Wastewater ... 95
27 Summary of Reactor Performance .............. 98
vii
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ACKNOWLEDGEMENTS
We would like to acknowledge the cooperation of the analytical
personnel of the Department of Energy's Oak Ridge National Laboratory,
Pittsburgh Energy Research Center, and Grand Forks Energy Research
Center in providing us with information as to the composition of coal
conversion wastewaters and the methodologies employed in the analysis.
Drs. Michael Guerin and Bruce Clark of ORNL and Kurt White of PERC were
especially helpful in this regard.
The assistance of Dr. Thomas W. Petrie, project officer, and
William J. Rhodes and T. Kelly Janes of the Industrial Environmental
Research Laboratory-RTF of the U.S. Environmental Protection Agency in
guiding this project and facilitating its performance are appreciated.
viii
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SECTION 1
INTRODUCTION
Several technologies for producing synthetic fuels from coal are
under development. While most of the emphasis has centered upon development
of efficient process technology to produce high energy, clean, synthetic
fuels, little information is available with respect to the nature of the
waste materials produced and the environmental impact of waste streams
from the various gasification and liquefaction processes.
Most coal conversion technologies incorporate or project aerobic
biological treatment as the principal means of removing phenol and the
other organic impurities in the wastewater. However, since the nature
and biodegradability of these other organic materials are not known, the
extent to which these components can be removed by biological treatment
cannot be reliably predicted. Synergisms and antagonisms due to the
complex nature of real wastewaters are especially uncertain. Moreover,
since even well-operated biological treatment processes typically remove
only 85-95% of the influent BOD and a significant portion of the wastewater
organics may not be biodegradable, it is doubtful that biological treatment
alone can provide an environmentally-acceptable discharge.
In view of these considerations, a need exists to identify the
nature and characteristics of aqueous discharges from coal conversion
processes and to assess their environmental impact, and to develop
satisfactory means for the treatment of these wastewaters in order that
they may be disposed of in an environmentally-acceptable fashion.
Accordingly, the purpose of this project is to assess the environmental
impact of wastewater contaminants originating from the production of
synthetic fuels from coal, and to evaluate, by bench-scale tests, alternative
wastewater treatment technologies for the control of these contaminants.
This report presents the results of a literature review and a
survey of facilities aimed at determining the chemical characteristics
of coal conversion wastewaters and at identifying specific organic
contaminants which might be found in such wastewaters. A preliminary
assessment of the aquatic impact of these wastewaters and of their
biological treatability is also presented.
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SECTION 2
CONCLUSIONS
An attempt has been made to determine the chemical characteristics
of wastewaters from coal gasification and coal liquefaction processes.
Approximately 60-80% of the total organic carbon appears to be phenolic
in nature, consisting of monohydric phenols, dihydric phenols, and
polyphenols. The remainder of the organic material consists of mono-
and polycyclic nitrogen-containing aromatics, oxygen- and sulfur-containing
heterocyclics, polynuclear aromatic hydrocarbons, and simple aliphatic
acids. The composition of the wastewaters appears to be relatively
uniform, especially with respect to the phenolic constituents, regardless
of the specific process technology and type of feed coal employed. At
the concentrations reported, the discharge of these wastewaters would
have an adverse impact on aquatic life and, as a result, a significant
degree of wastewater treatment is necessary.
With respect to the biodegradability of these constituents, there
is a significant body of literature available concerning the microbial
degradation of phenols, especially in pure cultures of microorganisms
and in single-substrate systems. This is especially true for both mono-
and dihydric phenols. Less information is available, however, with
regard to the biodegradability of the more highly-substituted phenols,
or of the other complex aromatic constituents of coal conversion wastewaters,
such as the mono- and polycyclic nitrogen-containing aromatics, the
oxygen- and sulfur-containing heterocyclics, and the polynuclear aromatic
hydrocarbons. Furthermore, little information is available regarding
the biodegradation of specific phenolic compounds in complex mixtures
such as those characteristic of coal conversion wastewaters.
Additionally, considering the needs from a wastewater treatment viewpoint,
there is also little information available regarding the rate at which
these compounds are microbially degraded in mixed cultures, and the
concentrations at which these compounds become inhibitory to microbial
degradation.
While aerobic biological processes appear to be among the methods
of choice for treating these wastewaters, the following types of information
are required in order to assess the biological treatability of these
coal conversion wastewaters and to develop suitable design and operating
guidelines: (a) more information on the biodegradability of the constituent
compounds; (b) biokinetic information describing the rate at which
degradation of the constituents takes place; (c) the concentration
levels at which microbial degradation of the constituents is inhibited;
and (d) how the constituents will behave in a composite mixture representative
of coal conversion wastewaters. In view of the paucity of information
available regarding the microbial degradation of many of the constituents
identified in coal conversion wastewaters, an experimental program to
provide such information has been developed and is now underway.
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SECTION 3
BACKGROUND
Conversion of coal to synthetic gaseous and liquid fuels represents
a plausible approach to meeting the nation's energy needs. Several
technologies for producing synthetic fuels from coal are under development.
While most of the emphasis has centered upon development of efficient
process technology to produce high energy, clean, synthetic fuels at
lowest process cost, little information is available with respect to
the nature of the waste materials produced and the environmental impact
of waste streams from the various gasification and liquefaction processes.
Wastewaters from coal conversion processes can originate from a
variety of sources and can be widely variable in composition depending
upon the specific process technology employed (operating temperature and
pressure, mode of contact between coal and steam, process sequence, gas
cleanup and separation technology, etc.). Additionally, the composition
of the wastewater is also dependent upon the nature of the feed coal as
shown in Table 1 (1)*. Many coal conversion technologies employ by-
product recovery systems for phenol and ammonia, two of the major constituents
of the wastewater as shown in the table. Phenol concentrations in the
solvent-extracted liquor, however, may still be appreciable and further
treatment of the waste streams may still be required.
Most coal conversion technologies incorporate or project aerobic
biological waste treatment processes (e.g., activated sludge, aerated
lagoons, etc.) as the principal means of treating the residual phenol
and other organic impurities in the wastewater. However, the nature and
biodegradability of these other organic materials which are included in
Table 1 as part of the COD (chemical oxygen demand) are not known.
Hence, the extent to which these other organic components can be removed
by biological treatment cannot be predicted.
Table 2 shows the types of organics which have been identified in
the tar from a coal gasification system. Many of the polynuclear aromatic
hydrocarbons listed are known carcinogens. It can be anticipated that
some of these contaminants will be found in the wastewaters from coal
conversion facilities and may comprise part of the COD.
Since even well-operated biological treatment processes typically
remove only 85-95% of the influent BOD (biochemical oxygen demand) and a
significant portion of the wastewater organics may not even be biodegradable,
it is doubtful that biological treatment alone can provide an environmentally-
acceptable discharge. Furthermore, many inorganic materials of environmental
concern may also be found in the wastewater. These include (see Table 1)
cyanides, thiocyanates, ammonia (even after stripping), and heavy metals.
*References for each section appear at the end of that section.
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TABLE 1. WATER QUALITY CHARACTERISTICS OF COAL CONVERSION WASTEWATERS.'
(ALL VALUES IN mg/1 EXCEPT pH.)
pH
Suspended Solids
Phenol
COD
Thiocyanate
Cyanide
NH
Chloride
Carbonate
Bicarbonate
Total Sulfur
Coke
Plant
9
50
2,000
7,000
1,000
100
5,000
-
-
-
-
Illinois
No. 6
Coal
8.6
600
2,600
15,000
152
0.6
8,100
500
6,000
11,000
1,400
Wyoming
Subbi-
tumi-
nous
Coal
8.7
140
6,000
43,000
23
0.23
9,520
-
-
-
-
Illi-
nois
Char
7.9
24
200
1,700
21
0.1
2,500
31
-
-
-
North
Dakota
Lignite
9.2
64
6,600
38,000
22
0.1
7,200
—
-
-
-
Western
Kentucky
Coal
8.9
55
3,700
19,000
200
0.5
10,000
—
-
-
-
Pitts-
burgh
Seam
Coal
9.3
23
1,700
19,000
188
0.6
11,000
—
-
-
-
*After Forney, et al. (1).
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TABLE 2. MASS SPECTROMETRIC ANALYSIS OF BENZENE-SOLUBLE TAR*
Structural type
(includes alkyl)
derivatives)
Benzenes
Indenes
Indans
Naphthalenes
Fluorenes
Ac enaphthenes
3-ring aromatics
Phenylnaphthalenes
4-ring pericondensed
4-ring catacondensed
Phenols
Naphthols
Indanols
Acenaphth eno 1 s
Phenanthrols
Dibenzofurans
Dibenzothiophenes
Benzonaphthothiophenes
Average molecular weight
Run HP-1
No. 92,
Illinois
No. 6 Coal
2.1
8.6
1.9
11.6
9.6
13.5
13.8
9.8
7.2
4.0
2.8
.9
-
2.7
6.3
3.5
1.7
(10.8)
212
Run HPL
No. 94,
Lignite
4.1
1.5
3.5
19.0
7.2
12.0
10.5
3.5
3.5
1.4
13.7
9.7
1.7
2.5
-
5.2
1.0
-
(3.8)
173
Percent, by Volume
Run HPM No. Ill,
Montana
Subbituminous
Coal
3.9
2.6
4.9
15.3
9.7
11.1
9.0
6.4
4.9
3.0
5.5
9.6
1.5
4.6
.9
5.6
1.5
-
(5.3)
230
Run HP-118
No. 118,
Pittsburgh
Seam Coal
1.9
6.1
2.1
16.5
10.7
15.8
14.8
7.6
7.6
4.1
3.0
.7
2.0
-
4.7
2.4
-
(8.8)
202
*After Forney, et al (1).
In view of these considerations, a need exists to:
(a) identify the nature and characteristics of aqueous discharges
from coal conversion processes and to assess their environmental
impact; and
(b) develop satisfactory means for the treatment of these
wastewaters in order that they may be disposed of in an
environmentally-acceptable fashion.
Accordingly, the purpose of this project is to assess the environmental
impact of wastewater contaminants originating from the production of
synthetic fuels from coal, and to evaluate, by bench-scale tests, alternative
wastewater treatment technologies for the control of these contaminants.
The project has been designed to be carried out in several phases
over a five-year period. The first phase, for which preliminary results
are presented in Section 4 of this report, consists of a review of the
literature and a survey of pilot- and full-scale coal conversion facilities
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to identify specific contaminants which might be found in coal conversion
wastewaters. Concentration ranges for these contaminants are estimated
and the potential effects of these contaminants on human health and
aquatic life are to be assessed based upon a review of the literature
and upon toxicity and water quality listings. A preliminary review of
the aquatic impact of coal conversion wastewater constituents is presented
in Section 5.
Phase 2 consists of a study of the biodegradability of selected
model organic compounds from the classes of organics identified in
phase 1. The investigation was designed to be conducted on a component
basis since it was anticipated, a priori, that certain compounds and
classes of organics would be common to all coal processing wastewaters
even though the exact composition might vary depending upon the particular
process scheme and cleanup and separation technology employed. (The
results reported in Section 4 confirm this hypothesis.) Section 6
presents a comprehensive review of the literature on microbial degradation
of the organic constituents which have been identified, and some preliminary
results of long-term BOD tests on several component organics.
The remaining phases of the 5-year project involve:
(a) experimental evaluation of the biological treatability
of coal conversion wastewater constituents, based in
part on the biodegradability results developed in phase 2;
(b) experimental evaluation of alternative physical-chemical
treatability techniques applied to the coal conversion
wastewater constituents;
(c) aquatic bioassay studies to assess the impact of various
constituents and composite samples on several forms of aquatic
life;
(d) toxicological investigations to evaluate the potential health
effects of various wastewater constituents and composites
following treatment;
(e) composite treatability analyses of actual and synthetic
coal conversion wastewaters, utilizing both biological and
physical-chemical techniques; and
(f) development of design and operating criteria for the
continuous treatment of coal conversion wastewaters.
REFERENCES
1. Forney, A. J., &t_ al_. 1974. Analysis of Tars, Chars, Gases, and
Water Found in Effluents from the Synthane Process. U. S. Bureau of
Mines Technical Progress Report 76, Pittsburgh Energy Research Center,
Pittsburgh, Pa.
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SECTION 4
CHEMICAL CHARACTERISTICS OF COAL CONVERSION WASTEWATERS
The first phase of this research investigation consisted of a
review of the literature and a survey of pilot-scale coal conversion
facilities. The purposes of these endeavors were to determine the
chemical characteristics of coal conversion wastewaters and to identify
the types of potential pollutants to be expected in wastewaters from
such facilities. This analysis was necessary in order to be able to
reasonably assess the aquatic impact of these wastewaters, and to develop
an appropriate set of wastewater treatment methodologies.
The constituents of these wastewaters have been identified during
this first phase of the project by reviewing the published literature,
visiting coal gasification and liquefaction research and demonstration
installations, and analyzing reports and project documents from a variety
of coal conversion operations. Table 3 presents the results of an
analysis of the condensate wastewater generated from the Synthane gasification
of six different types of coal (1). The wastewater characteristics of
the weak ammonia liquor from a coke plant are presented for purposes of
comparison. The waste condensate streams appear to be somewhat alkaline
and contain rather substantial concentrations of ammonia. The concentration
of organic material, represented by the COD, consists for the most part
of phenol. Table 4 indicates, however, that phenol accounts for only 21
to 46% of the COD in the condensate samples; the remaining 54 to 79% of
the COD, is apparently due to the presence of other organic components of
the waste streams. Table 4 was developed by calculating the COD-equivalent
of the phenol concentrations given in Table 3, using a stoichiometric
factor of 2.38 gins, of COD per gm. of phenol from the equation:
6C02 + 3H20 (1)
phenol
Bromel and Fleeker (2) examined some general properties of raw and
processed wastewater from the Lurgi process plant at Sasolburg, South
Africa. Table 5 shows that the raw Lurgi wastewater is similar to that
from Synthane in terms of its alkaline pH and high ammonia and COD
concentration. The raw wastewater consists of the condensate from the
gasifier (gas liquor) after tar and oil separation. The processed
wastewater refers to the gas liquor following phenol and ammonia' extraction.
In order to determine the nature of the organic species comprising
the COD and TOC (total organic carbon) , Bromel and Fleeker conducted a
series of chromatographic separations and identified and quantified the
components reported in Table 6. It is apparent, that, of the specific
organic compounds identified, phenol and its methyl substituents, the
cresols (methylphenols) and xylenols (dimethylphenols) , are the major
organic components of the condensate. Polyhydric phenols were not
determined. The other major classes identified are the fatty acids
(aliphatic acids) and the aromatic amines consisting of aniline and the
heterocycle pyridine and its methyl derivatives. Quinoline and alkyl
-------
00
TABLE 3. BY-PRODUCT WATER ANALYSIS FROM SYNTHANE GASIFICATION OF
VARIOUS COALS.* (ALL VALUES IN mg/1 EXCEPT pH.)
PH
Suspended Solids
Phenol
COD
Thiocyanate
Cyanide
NH
Chloride
Carbonate
Bicarbonate
Total Sulfur
Coke
Plant
9
50
2,000
7,000
1,000
100
5,000
-
-
-
-
Illinois
No. 6
Coal
8.6
600
2,600
15,000
152
0.6
8,100
500
6,000
11,000
1,400
Wyoming
Subbi-
tumi-
nous
Coal
8.7
140
6,000
43,000
23
0.23
9,520
-
-
-
-
Illi-
nois
Char
7.9
24
200
1,700
21
0.1
2,500
31
-
-
-
North
Dakota
Lignite
9.2
64
6,600
38,000
22
0.1
7,200
-
-
-
-
Western
Kentucky
Coal
8.9
55
3,700
19,000
200
0.5
10,000
-
-
-
-
Pitts-
burgh
Seam
Coal
9.3
23
1,700
19,000
188
0.6
11,000
-
-
-
-
*After Forney, et al. (1).
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TABLE 4. PERCENTAGE OF COD ATTRIBUTABLE TO PHENOL IN SYNTHANE GASIFICATION
BY-PRODUCT WATER.*
Component
Chemical Oxygen
Demand , mg . 1
Phenol, mg/1
Phenol, mg/1 of
equivalent COD
Phenol, % of
COD
Coke
Plant
7,000
2,000
4,760
68.0
Illinois
No. 6
Coal
15,000
2,600
6,188
41.2
Wyoming
Subbi-
tumi-
nous
Coal
43,000
6,000
14,280
33.2
Illi-
nois
Char
1,700
200
476
28.0
North
Dakota
Lignite
38,000
6,600
15,708
41.3
Western
Kentucky
Coal
19,000
3,700
8,806
46.3
Pitts-
burgh
Seam
Coal
19,000
1,700
4,046
21.3
*Raw data from Forney, j^t al (1) .
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TABLE 5. SOME GENERAL PROPERTIES OF RAW AND PROCESSED
WASTEWATER FROM THE LURGI-PROCESS PLANT AT
SASOLBURG, SOUTH AFRICA*
Values
Parameter
Chemical Oxygen Demand (mg/1)
Organic Carbon (mg/1)
Total Dissolved Solids (mg/1)
pH
Ammonia (mg/1)
Raw
Waste
Water
12,500
4,190
2,460
8.9
11,200
Processed
Waste
Water
1,330
**
596
8.2
150
*After Broinel and Fleeker (2).
**not determined
amines were found in lesser amounts. It is apparent from the table that
the phenol extraction step is relatively efficient in separating the
monohydric phenols and even the aromatic amines from the gas liquor.
In order to determine what fraction of the COD and TOC reported in
Table 5 for the Sasol wastewater could be accounted for by the specific
organics identified in Table 6, a series of calculations was performed
to determine the COD and TOC-equivalents of the specific compounds identifed.
The basis for these calculations is shown in Table 7- The TOC and COD-
equivalents of the identified organic constituents are listed in Table
8. The total COD of the raw wastewater attributable to these indicated
constituents is 6738 mg/1, of which the monohydric phenols comprise
5915 mg/1. The monohydric phenols contribute 1866 mg/1 of TOC out
of the total TOC of 2143 mg/1 accounted for by the indicated constituents.
However, if the COD and TOC of these organic components are compared to
the total concentrations reported in Table 5 for the same sample, it
is shown (Table 9) that 46.1% of the COD and 48.9% of the TOC of the raw
wastewater are not accounted for. Similarly, a very small percentage of
the COD (and, also probably of the TOC) of the processed wastewater is
attributable to the residual aliphatic acids following phenol extraction.
It should be noted that the data presented in Tables 5 and 6
by Bromel and Fleeker (2) were derived from single samples of the aqueous
gas liquor and the phenol-extracted gas liquor. The age of the samples
was not accurately known, but is believed to have been less than six
months for the raw wastewater and less than one month for the processed
wastewater. The analyses were completed within four months following
receipt of the samples (2).
10
-------
TABLE 6. CONCENTRATION OF ORGANIC COMPOUNDS FOUND IN RAW AND
PROCESSED WASTEWATER FROM THE LURGI-PROCESS PLANT
AT SASOLBURG, SOUTH AFRICA.*
Concentration (mg/1)
Compound Raw Waste Water Processed Waste Water
Fatty Acids
Acetic Acid 171 123
Propanoic Acid 26 30
Butanoic Acid 13 16
2-Methylpropanoic Acid 2 5
Pentanoic Acid 12 7
3-Methylbutanoic Acid 1 5
Hexanoic Acid 1 8
Monohydric Phenols
Phenol 1,250 3.2
2-Methylphenol 340 0.2
3-Methylphenol 360 0.2
4-Methylphenol 290 0.2
2,4-Dimethylphenol 120 **
3,5-Dimethylphenol 50 **
Aromatic Amines
Pyridine
2-Methylpyridine
3-Methylpyridine
4-Methylpyridine
2 , 4-Dimethylpyridine
2 , 5-Dimethylpyridine
2 , 6-Dimethylpyridine
Aniline
117
70
26
6
1
1
1
12
0.45
0.05
0.05
0.05
**
**
**
**
*After Bromel and Fleeker (2)
**Not found
11
-------
TABLE 7. COD AND TOC-EQUIVALENTS OF ORGANIC
CONSTITUENTS OF SASOL WASTEWATER.
Reaction
Propanoic Acid
Chemical Oxygen
Demand,
gm/gm
Total
Organic Carbon,
gm/gm
Phenol
C,H,OH + 7 09 -> 6C00 + 3H 0
O J Z Z Z
Methylphenol (cresol)
C?H80 + 8.5 02 -> 7C02 + 4H20
Dimethylphenol (xylenol)
C8H1()0 + 10 02 -> 8C02 + 5H20
Pyridine
C H N + 5.5 09 -> 5C09 + ELO + NH
j j Z Z j£ j
Methylpyridine
C,ELN + 7 09 -»• 6C09 + 2H 0 + NH
o / Z Z Z J
Dimethylpyridine
Aniline
C,H,N + 7 09 -> 6C09 + 2H90 + NH_
D / Z Z Z j
Acetic Acid
CH COOH + 2 09 ->- 2C09 + 2H?0
J ^> ^ £+
2.38
2.52
2.62
2.23
2.41
2.54
2.41
1.07
0.77
0.78
0.79
0.76
0.77
0.79
0.77
0.40
3.5
1.51
0.49
Butanoic Acid
1.82
0.60
Methylpropanoic Acid
CH0 + 21/4 0 -»• 4C0 + 9/2
1.89
0.54
Pentanoic Acid
C5H10°2 + 6'
° * 5C0
5H2°
Methylbutanoic Acid
C5H11°2 + 27/4 °2 = 5C°2
Hexanoic Acid
C6H12°2 + 8 °2 = 6C02 + 6H2°
H2°
2.04
2.10
2.21
0.59
0.58
0.62
12
-------
TABLE 8. CONCENTRATION OF ORGANIC COMPOUNDS, AS COD AND TOC, FOUND IN THE
RAW AND PROCESSED WASTEWATER FROM THE LURGI-PROCESS PLANT AT
SASOLBURG, SOUTH AFRICA.*
Concentration, mg/1
Raw Wastewater
Compounds
Fatty Acids
acetic acid
propanoic acid
butanoic acid
2-methylpropanoic acid
pentanoic acid
3— methylbutanoic acid
hexanoic acid
Monohydric Phenols
phenol
2-methylphenol
3-methylphenol
4-methylphenol
2 , 4-dimethylphenol
3 , 5-dimethylphenol
Aromatic Amines
pyridine
2-methylpyridine
3-methylpyridine
4-methylpyridine
2 , 4-dimethylpyridine
2 , 5-dimethylpyridine
2 , 6-dimethylpyridine
aniline
TOTAL
COD
183
39.3
23.7
3.8
24.5
2.1
2.2
278.6
2975
857
907
731
314
<131
5915
261
169
62.7
14.5
<2.5
<2.5
<2.5
28.9
544
6738
TOC
68.4
12.7
7.8
1.1
7.1
0.6
0.6
98.3
963
265
277
226
95
<39.5
1866
88.9
53.9
20.0
4.6
<0.8
<0.8
<0.8
9.2
179
2143
Processed Wastewater
COD
131.6
45.3
29.1
9.5
14.3
10.5
17.7
258
7.6
<0.5
<0.5
<0.5
-
-
9.1
1.0
<0.12
<0.12
<0.12
-
-
-
-
1.4
269
TOC
49.2
14.7
9.6
2.7
4.1
2.9
5.0
88.2
2.5
<0.2
<0.2
<0.2
-
-
3.1
0.34
<0.04
<0.04
<0.04
-
-
-
-
0.5
92
*Raw data from Bromel and Fleeker (2).
13
-------
TABLE 9. PERCENTAGES OF UNIDENTIFIED COD AND TOG IN SASOL WASTEWATER*
Processed
Parameter Raw Wastewater Wastewater
Total COD, mg/1 12,500 1,330
COD of Identified Constituents, mg/1 6,738 269
% of COD Unidentified 46.1 79.8
Total TOG, mg/1 4,190
TOC of Identified Constituents, mg/1 2,143 92
% of TOC Unidentified 48.9
*Raw data from Bromel and Fleeker (2).
It is apparent from Tables 4 and 9 that many other organic species
are present in coal conversion wastewaters, and that a need exists for
further identification and quantitation of these constituents. Along
these lines, Schmidt, Sharkey and Friedel (3) have employed mass spectrometric
methods to determine the nature of the organic contaminants in condensate
waters from the Synthane gasification of coal. The Synthane process
produces about 0.4-0.6 tons of condensate water per ton of coal gasified
(1). The condensate waters from the gasification of six different coals
were extracted with methylene chloride and were identified using high
resolution mass spectrometry, combined gas chromatography-mass spectrometry,
and low-voltage mass spectrometry. Table 10 summarizes the results of
these spectrometric analyses for the six different coals gasified.
Again, phenol appears to be the major organic component of the condensate
waters and, along with the other monohydric phenols, dihydric phenols, and
polyphenols, constitute approximately 60 to 80% of the methylene chloride
extract. Several other classes of organics appear to be represented,
including heterocyclic compounds such as the pyridines and furans, and
polycyclic components such as indenols, indanols, naphthols, quinolines,
and indoles. It is interesting to note that, regardless of the type of
coal gasified, the composition of the condensate water, in terms of the
component organics and their concentrations, is relatively uniform. It
should also be noted that the constituents reported by Bromel and
Fleeker (2) in Table 6 are consistent with the listing by Schmidt,
Sharkey and Friedel (3) in Table 10.
Expanding on this effort to identify organic constituents in wastewaters
from coal gasification and coal liquefaction operations from various
different sources, Table 11 is a summary of information gathered from
the several references cited. The organics have been grouped into
various classes and include monohydric and dihydric phenols, polycyclic
hydroxy compounds (polyphenols), monocyclic and polycyclic nitrogen-
containing aromatics (including heterocyclic compounds such as the
pyridines, quinolines, indoles, acridines and carbazoles, and the amino-
benzenes), aliphatic acids, and a group of miscellaneous other compounds.
The check (^) marks indicate that the compound in question has been
identified but not quantified. The notation ($) indicates that the
concentrations given are for a group of compounds, but that the individual
components within the group have not been quantified, e.g., 140-1170
mg/1 in column 1 for the C.-phenols include the isomers of xylenol
14
-------
TABLE 10. CONTAMINANTS IN PRODUCT WATER FROM SYNTHANE
GASIFICATION OF VARIOUS COALS.* (ALL
CONCENTRATIONS IN mg/1.)
Montana N. Dak. Wyo. W. Ky. Pgh.
Component Illinois No. 6 (HVBB) (Sub) (Lig) (Sub) (HVBB) (HVAB)
Phenol 3,400 2,660 3,160 2,790 4,050 2,040 1,880
Cresols 2,840 2,610 870 1,730 2,090 1,910 2,000
C -Phenols 1,090 780 240 450 440 620 760
C3-Phenols 110 100 30 60 50 60 130
Dihydrics 250 540 130 70 530 280 130
Benzofuranols 70 100 80 60 100 50 70
Indanols
Acetophenones 150 100 140 110 110 90 120
Hydroxy- ~~)
BenzaldehydeV 60 110 - - 60 50 80
i-1 Benzole Acid j
Naphthols 160 110 160 140 80 160 170
Indenols 90 90 70 50 60 80 20
Benzofurans - - 10 10 - - 110
Dibenzofurans - - _ _ - - -
Blphenols 40 20 - 40 20 60
Benzothlo-
Phenols
Pyridines
Quinolines
Indoles
110 60
60
- -
20
-
270
20
70
10
220
10
30
20
120
—
20
70
30
—
40
20
540
10
40
After Schmidt, et al. (3).
-------
TABLE 11. SUMMARY: ORGANIC CONSTITUENTS IN COAL CONVERSION WASTEWATERS
(ALL CONCENTRATIONS IN mg/1.)
Monohydric Phenols
Phenol
o-Cresol
m-Cresol
p-Cresol
2,6-Xylenol
3,5-Xylenol
2,3-Xylenol
2,5-Xylenol
3,4-Xylenol
2,4-Xylenol
o-Ethylphenol
m-Ethylphenol
p-Ethylphenol
3-Methyl,6-Ethylphenol
2-Methyl,4-Ethylphenol
4-Methyl,2-Ethylphenol
5-Methyl,3-Ethylphenol
2,3,5-Trimethylphenol
o-Iospropylphenol
Dihydric Phenols
Catechol
3-Methylcatechol
4-Methylcatechol
3,5-Dimethylcatechol
3,6-Dimethylcatechol
Methylpyrocatechol
Resorcinol
5-Methylresorcinol
Synthane
(1)
Oil
Shale
(2)
Syn-
thane
(3)
COED
(4)
SRC
(5)
Lurgi-
Westfield
(6)
Syn- Lurgi-
thane Sasol
(7) (8)
Lurgi- Hydro-
GRFERC Carb oni z.
(9) (10)
COED
(11)
1000-4480 10 2100
T" 30 670
530-3580 T T
_j
140-
2£ 1800
40
230
30
.170 250
100
30
t
2100
650
T
isbo
To
240
40
220
900
30
1200-3100 T" 1250
153-343 2209 340
170-422
160-302
T
100-393
360
290
50
5647
T
1965
f
453
1
2185
120
20-150
±
•
•S
y
66
40
190-555
30-394
110-385
V
0-45
176-272
40-64
1700
~
2000
2000
v/
(continued)
-------
TABLE 11. (continued)
Synthane
(1)
Oil
Shale
(2)
Syn-
thane
(3)
COED
(4)
SRC
(5)
4-Methylresorcinol
2-Methylresorcinol
2,4-Dimethylresorcinol
Hydroquinone
Polycyclic Hydroxy Compounds
Y-Naphthol
B-Naphthol
Methylnaphthol
Indenol
C -Indenol
4-Indanol
C.-Indanol
Biphenol
Biphenyl
Monocyclic N—Aromatics
Pyridine
Hydroxypyridine
Methylhydroxypyridine
Methylpyridine
Dimethylpyridine
Ethylpyridine
C -Pyridine
C -Pyridine
Analine
Methylaniline
Dimethylaniline
Polycyclic N-Aromatics
Quincline
Methylquinoline
Lurgi-
Westfield
(6)
0-36
Syn-
thane
(7)
Lurgi-
Sasol
(8)
Lurgi- Hydro-
GRFERC Carboniz. COED
(9) (10) (11)
20*00
i.
T
30-290
10
30
20-110
40-150
±
0-110
66
19
30-580
1
T
21
9
11
7
27
117
104
12
10
10
T
20
(continued)
-------
TABLE 11. (continued)
Dimethylquinoline
Ethylquinoline
Benzoquinoline
Methylbenzoquinoline
Tetrahydroquinoline
Methyltetrahydroquinoline
Isoquinoline
Indole
Methylindole
Dimethylindole
Benzoindole
Methylbenzoindole
Carbazole
Methylcarbazole
Acridine
Methylacridine
Aliphatic Acids
Acetic Acid
Propanoic Acid
n-Butanoic Acid
2-Methylpropanoic Acid
n-Pentanoic Acid
3-Methylbutanoic Acid
n-Hexanoic Acid
n-Heptanoic Acid
n-Octanoic Acid
n-Nonanoic Acid
n-Decanoic Acid
Synthane
(1)
0-100
Oil
Shale
(2)
Syn-
thane
(3)
COED
(4)
SRC
(5)
v/
Lurgi-
Westfield
(6)
Syn-
thane
(7)
Lurgi-
Sasol
(8)
Lurgi- Hydro-
GRFERC Carboniz. COED
(9) (10) (11)
63
0-110
1
600
210
130
200
250
260
250
100
50
620
60
20
10
20
600
90
40
30
30
171
26
13
2
12
1
1
(continued)
-------
TABLE 11. (continued)
Others
Benzofurans
Benzofuranols
Benzo thiopheno Is
Acetophenones
Hydroxybenzaldehyde
or Benzole Acid
Synthane
(1)
10-110
50-100
10-110
90-150
50-110
Oil Syn- Lurgi- Syn- Lurgi- Lurgi- Hydro-
Shale thane COED SRC Westfield thane Sasol GRFERC Carboniz.
(2) (3) (4) (5) (6) (7) (8) (9) (10)
74
COED
(11)
-------
(dimethylphenol) and ethylphenol. A range of values, e.g., 1000-4480
mg/1 for phenol in column 1, indicates that several samples have been
analyzed and the concentrations measured are within the given range.
Column 1 is derived from the previously-discussed mass spectrometric
analysis of the methylene chloride extract by Schmidt, Sharkey and
Friedel (3) for the condensate waters from the Synthane gasification of
six different types of coal under different process conditions. Columns
2, 3 and 4 include data from Ho, Clark and Guerin (4) and were obtained
by gas chromatography using Tenax columns and flame ionization detection.
Identifications were made from comparisons of the chromatograms with
retention time data for reagent grade compounds. Some identifications were
confirmed by gas chromatography-mass spectrometry. Quantitation was
made by integrating peak areas from the chromatogram and comparing with
standards of known concentration. The oil shale by-product water (column
2) was obtained by centrifugation of an oil/water emulsion product from
a simulated in-situ retort run at the Laramie (Wyoming) Energy Research
Center. The gasification by-product water (column 3) was a sample of
filtered condensate water from the Synthane process, provided by the
Pittsburgh (Pennsylvania) Energy Research Center. The coal liquefaction
by-product sample (column 4) was filtered water from the first-stage gas
scrubber from the COED (Char Oil Energy Development) liquefaction process,
provided by FMC Corporation, Princeton, New Jersey.
The information in column 5 results from a characterization by
Fruchter et al. (5) of organics in coal-derived liquids from the Solvent
Refined Coal Plant at Ft. Lewis, Washington. The constituents of the
raw process water were separated into acidic, basic, neutral, and polyaromatic
fractions and each fraction was separated further by gas chromatography.
Gas chromatography/mass spectrometry was then employed to identify the
components. The constituents indicated in column 5 were positively
identified, but not quantified.
Column 6 contains data collected by Janes and Rhodes (6) from the
Lurgi gasification facility in Westfield, Scotland. The data were
obtained for tar water and oil water samples from old plant records, and
the analytical and sample-handling procedures were not reported. Nevertheless,
the constituents and the concentrations appear to be consistent with
those in other reports.
Column 7, after Neufeld and Spinola (7), contains data for a condensate
sample from the Synthane gasification of an Illinois No. 6 coal. The
organic content was analyzed by direct gas chromatography of acidic and
basic fractions and identification was based on relative retention time
data.
The data in column 8 for the Lurgi facility in Sasolburg, South
Africa are from the report by Bromel and Fleeker (2) discussed above in
connection with Tables 5-9.
Column 9 contains the results of a mass spectrometric analysis of
the soluble organic material in a composite sample of aqueous liquor
from the slagging Lurgi gasifier at the Grand Forks (North Dakota)
20
-------
Energy Research Center (8). Phenol, cresol, and xylenol accounted for
approximately 80% of the organic constituents, while the remaining
material consisted of heavier organic components, including polynuclear
aromatic hydrocarbons, suspended and dissolved to some degree in the
liquor.
The information in column 10 is from an analysis by Jolley, Pitt,
and Thompson (9) of an aqueous stream from the product scrubber of a
bench-scale hydrocarbonization coal liquefaction operation. The samples
were analyzed by high performance liquid chromatography, and the separated
constituents were identified by a multiple-analytical procedure involving
gas chromatography and mass spectrometry.
Column 11 cites specific organics identified (10) iff- an aqueous
sample from the product separator (2nd stage liquor) of the COED coal
liquefaction pilot plant. The constituents were separated by high-
resolution anion exchange chromatography, and a variety of different
analytical techniques were employed for identification and quantitation.
With reference to the material contained in Table 11, it is important
to note that the components identified- and the concentrations reported
are from single grab samples of process streams collected from the
various facilities and locations cited. The fact that they are analyses
of grab samples from processes still under development means that the
concentrations may not be truly representative of on-line, commercial,
steady-state coal gasification and liquefaction operations. Additionally,
the number and type of organic compounds listed are limited,, in part, by
the analytical methodologies employed for extracting, separating, and
identifying the constituents of the waste streams. Nevertheless, Table 11
reflects the present state of knowledge concerning the organic composition
of coal conversion wastewaters.
While it might have been predicted, a priori, that the composition
of wastewaters from coal conversion facilities would vary depending upon
the specific process technology (operating temperature and pressure,
mode of contact between coal and steam, process sequence, gas cleanup
and separation technology, etc.) and type of feed coal employed, Table 11
suggests that the composition of coal gasification and liquefaction
wastewaters is relatively uniform, especially with respect to the phenolic
constituents. Less information is available regarding the presence of
specific N-containing aromatics, other polycyclic and heterocyclic
compounds, and polynuclear aromatic hydrocarbons. Table 12 lists some
of the PAH's identified by Fruchter, at al. (5) in the raw process
wastewater from the Solvent-Refined Coal facility in Ft. Lewis, Washington,
but the quantitation and wide-spread occurrence of these PAH's in coal
conversion wastewaters have not been established.
Additional high performance liquid chromatography and gas chromatography/
mass spectrometry analyses of aqueous samples from a variety of coal
conversion operations are being carried out at the present time by a
number of research laboratories with which contact has been made during
this first phase of our study. As more information regarding the composition
of coal conversion wastewaters is collected, Tables 11 and 12 will be
expanded.
21
-------
TABLE 12. POLYNUCLEAR AROMATIC HYDROCARBONS
IN SRC RAW PROCESS WATER*
PAH
Methylindane
Tetralin
Dimethyltetralin
Naphthalene
2-Methylnaphthalene
Dlmethylnaphthalene
2-Isopropylnaphthalene
1-Isopropylnaphthalene
Biphenyl
Acenaphthalene
Dijnethylbiphenyl
Dibenzofuran
Xanthene
Dibenzo thiophene
Methyldibenzothiophene
Dimethyldibenzothiophene
Thioxanthene
Fluorene
9-Methylf luorene
1-Methylfluorene
Anthracene/Phenanthrene
Methylphenanthrene
C -Anthracene
Fluoranthene
Dihydropyrene
Pyrene
Concentration
(mg/1)
15
0.1
0.5
5
2
0.3-2
0.7
2
0.2
0.1
0.2-0.5
0.6
0.1
1.5
0.1
0.05
0.1
0.3
0.3
0.2
1.1
0.2-0.3
0.05
0.4
0.05
0.6
Identified But Not
Yet Quantitated
Methylpyrene
Benzof luorene
C~-Pyrene
C^-Fluoranthene
Tetrahydrochrysene
Chrysene
Methylbenzof luorene
C3~Pyrene
C --Fluoranthene
Methylchrysene
Methylbenzanthracene
Cholanthrene
Tetrahydrobenzof luoranthene
Tetrahydrobenzopyrene
Benzopyrene
Methylbenzopyrene
Methylbenzof luoranthene
Benzof luoranthene
*After Fruchter, et al. (5)
22
-------
REFERENCES
1. Forney, A. J., W. P. Haynes, S. J. Gasior, G. E. Johnson, and J. P.
Strakey. 1974. Analysis of Tars, Chars, Gases, and Water in Effluents
from the Synthane Process. U. S. Bureau of Mines Technical Progress
Report 76, Pittsburgh Energy Research Center, Pittsburgh, Pa.
2. Bromel, M. C. and J. R. Fleeker. 1976. Biotreating and Chemistry
of Waste Waters from the South African Coal, Oil and Gas Corporation
(Sasol) Coal Gasification Plant. Internal Report, Department of
Bacteriology, North Dakota State Univ., Fargo, N.D.
3. Schmidt, C. E., A. G. Sharkey, and R. A. Friedel. 1974. Mass
Spectrometric Analysis of Product Water from Coal Gasification.
U. S. Bureau of Mines Technical Progress Report 86, Pittsburgh
Energy Research Center, Pittsburgh, Pa.
4. Ho, C. H. , B. R. Clark, and M. R. Guerin. 1976. Direct Analysis of
Organic Compounds in Aqueous By-Products from Fossil Fuel Conversion
Processes: Oil Shale Retorting, Synthane Coal Gasification and COED
Liquefaction. J. Environ. Sci. Health, All(7), 481-489.
5. Fruchter, J. S., J. C. Laul, M. R. Petersen, and P. W. Ryan. 1977.
High Precision Trace Element and Organic Constituent Analysis of Oil
Shale and Solvent Refined Coal Materials. Symposium on Analytical
Chemistry of Tar Sands and Oil Shale, Division of Petroleum Chemistry.
American Chemical Society, New Orleans, La.
6. Janes, T. K. and W. J. Rhodes, Industrial Environmental Research
Laboratory, Environmental Protection Agency, personal communication.
7. Neufeld, R. F. and A. A. Spinola. 1978. Ozonation of Coal Gasification
Plant Wastewater. Environ. Sci. Tech., 12(4), 470-1.
8. Gronhovd, G. H. 1977. Quarterly Technical Progress Report. GRFERC/
QTR-77/2. Grand Forks Energy Research Center, Grand Forks, N.D.
9. Jolley, R. L., W. W. Pitt, and J. E. Thompson. 1977- Organics in
Aqueous Process Streams of a Coal Conversion Bench-Scale Unit Using
the Hydrocarbonization Process: HPLC and GC/MS Analysis. Environmental
Technology Annual Technical Meeting of the Institute of Environmental
Sciences, Los Angeles, Calif.
10. Shults, W. D. 1976. Preliminary Results: Chemical and Biological
Examination of Coal Derived Materials. ORNL/NSF/EATC-18, Oak Ridge
National Laboratory, Oak Ridge, Tenn.
23
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SECTION 5
POTENTIAL AQUATIC IMPACT OF ORGANIC CONSTITUENTS
OF COAL CONVERSION WASTEWATERS
There Is general agreement that most coal conversion processes will
produce relatively contaminated wastewaters. However, little is known
about the biological impact such wastes will have upon receiving waters.
The lack of information reflects the fact that coal conversion technology
has only recently emerged, and no commercial systems have yet been constructed
in the U. S. While ultimate evaluation of the biological impact resulting
from the discharge of wastewaters into aquatic ecosystems must await the
construction and continuous operation of commercial scale conversion systems,
interim predictive efforts are mandated by the number of highly toxic,
mutagenic, and carcinogenic compounds known or anticipated to occur in
coal conversion wastes. The objectives of this section are to: (a) identify
potential problems expected from coal conversion wastewaters; (b) review
the literature pertaining to toxic effects of constituents in the waste-
water; and (c) discuss existing gaps in knowledge concerning the potential
impact of coal conversion wastewater constituents on aquatic environments.
AQUATIC POLLUTION PROBLEMS: GENERAL CONSIDERATIONS
Currently, efforts to assess the impact of coal conversion wastewaters
on aquatic environments are in a predictive rather than descriptive phase.
The limited availability of coal conversion wastewaters precludes extensive
experimental assessment. The impact such effluents will have can only be
based on knowledge of effluents thought to be similar in composition, or
from an analysis of existing toxicity data on waste constituents. Neither
approach is wholly satisfactory. Comparisons with existing coal-related
industrial effluents would perhaps provide the most meaningful appraisal,
but such information is limited.
In Section 4, it was suggested that composition of coal conversion
wastewaters will be similar to those from coking operations and petroleum
refineries. Several authors have investigated the toxicity of coal-
processing wastes to fish, but few generalizations can be derived from
the available literature. Wastes from the production of "illuminating
gas" by the destructive distillation of coal were demonstrated to be
lethal to fish as early as 1917 (1), but the toxicity varied to such a
degree that a general statement concerning its overall effects could not
be made. Herbert (2) stated that the composition and volume of spent
still liquors from coal carbonization will vary with the nature of the
coal and with the design and operation of the plant, but that ammonia,
sulfides, thiosulfates, and monohydric phenols constituted the most
toxic components of the waste. Rainbow trout exposed to 2-10 ml/1 of
gas liquor died within 0.25-1.25 hrs. in laboratory tests. A 48-hr LC5Q
(concentration lethal to 50% of the test organisms in 48 hrs.) of 5.8 mg/1
of gas liquor phenols has also been reported for rainbow trout (3). The
only other reference dealing with coal carbonization effluents documented
a massive fish kill caused by an intermediate oil from coke ovens (4).
Other references exist, but are restricted to individual waste constituents
24
-------
rather than combined effluent toxicity.
Since the constituents of fossil fuel wastes share common character-
istics, certain generalizations about the toxicity of coal conversion
wastes may be inferred from petroleum refinery wastewater toxicity data.
Reliance on such data is necessary becuase parallel information from
existing coal processing wastes is scant. The variable acute toxicity
of refinery effluents is well known (5,6). Acute lethal toxicity is
usually attributed to phenols, ammonia, and hydrogen sulfide, but assess-
ment of effluent toxicity based solely on the chemical characteristics
of these constituents may be misleading. Heavy metals and cyanides as
well as a number of other inorganic and organic constituents may be
present in such wastes. To what degree they interact with respect to
toxicity is largely unknown.
The effects of petrochemical effluents on aquatic organisms were
recently reviewed (7), and factors that affect pollutional characteristics
of effluent components were listed. Included were the degree of waste
treatment, water quality characteristics of the receiving stream,
synergistic and antagonistic interactions, and microbial degradation of
organic waste components. Bacterial activity has the positive effect of
degrading oils and other organic compounds, but oxygen depletion may
contribute additional pollution problems. Aquatic organisms require
dissolved oxygen in order to survive. The discharge of wastes with large
concentrations of biodegradable organics results in oxygen depletion,
thereby making the receiving water unsuitable for aquatic biota.
Additionally, when bacteria oxidize carbon compounds to carbon dioxide
and water, the carbon dioxide may be assimilated bv algae. Given
sufficient amounts of inorganic nitrogen and phosphorus, more algal
growth will occur in waters high in BOD than in low BOD siutations.
Other organic components of petrochemical wastes may promote algal
growth making such wastewaters potential contributors to eutrophication.
Oxygen depletion may also inhibit microbial degradation of toxic organics,
increasing their persistence in the aquatic environment. Additionally,
most toxic substances become even more toxic at low dissolved oxygen
levels. Thus, petrochemical wastes released in toxic concentrations can
eliminate fish, either directly or through the destruction of lower
organisms on which they feed.
Although acute toxicity of coal conversion effluents will certainly
be a problem, chronic effects may be of equal or greater importance.
Long-term bioassays of treated oil refinery wastes indicated that complex
refineries produced effluents containing low-level toxins which caused
cumulative deleterious effects (8). Constituents which produce chronic
effects are not immediately lethal, but can have long-term significance
for the survival of ecologically important species. Chemically-induced
impairment of behavior of physiological functions can ultimately affect
growth and reproduction. Oil and other organic pollutants may include
carcinogenic and mutagenic compounds. From genetic studies in general,
a large majority of mutations are known to be detrimental to the survival
of young, and many are lethal.
Several organic components of complex organic wastes impart
unpleasant tastes and odors to water, and produce tainted tastes in fish
25
-------
and shellfish (7,9). Although tainted organisms apparently survive
without ill effects, they may be rendered unfit for human consumption,
adversely affecting economics of the fisheries industry. If undetected,
consumption of contaminated water and seafood by humans may pose a
potential hazard to public health. Furthermore, bioaccumulation of
organic compounds through the aquatic food web may result in problems
wholly unanticipated at present.
A general assessment of potential environmental problems created
by coal conversion effluents was recently presented (10). A summary of
the results is presented in Table 13. Five major classes of organic
compounds were identified as being of particular concern. Each class
was assessed according to: (a) concentration ranges anticipated in
effluents; (b) removal efficiency by waste treatment systems; (c) acute
toxicity; (d) chronic toxic effects on aquatic organisms; and
(e) environmental transport and persistence. These findings suggest
that while phenols and monoaromatic hydrocarbons are the major components
of coal conversion wastewaters, their environmental impact may be far
less detrimental than that of the polycyclic and heteroatomic compounds.
Besides the five major classes of organic constituents addressed in the
table, effluents will also include lesser concentrations of carboxylic
acids, ethers, esters, furans, tetralins, aldehydes, organometallics,
and other compounds.
Ambient level goals for a number of hazardous pollutants were
recently calculated and compiled by Cleland and Kingsbury (11). They
list minimum acute toxicity effluent values (MATE's) for water, defined
as the concentration levels of contaminants in water that will not evoke
significant harmful responses in exposed humans or to the ecology, provided
the exposure is of limited duration. Similarly, estimated permissible
concentrations (EPC's) are given, defined as the estimated level of a
substance for continuous exposure that will not result in toxic effects
to humans or to the ecology. MATE's and EPC's based upon health and
ecological considerations relevant to coal conversion wastewaters are
summarized in Tables 14 and 15, respectively. EPC's were calculated
according to different criteria which are defined in Table 16.
In contrast to data for health considerations (Table 14), fewer
data are currently available concerning the ecological effects of coal
conversion wastewater constituents (Table 15). In nearly all cases,
EPC's based on ecological considerations are derived from concentrations
that produce tainting of fish flesh. With the exception of phenolic
compounds, it is of interest to note that, where data are available,
MATE's based on aquatic organisms are less than those calculated for
humans. A comparison of the degree of sensitivity of fish and human
beings to acute intoxiciation by pollutants (12) has shown that fish
proved more sensitive in 97% of the cases. Therefore, it has been
suggested (13,14) that standards to protect aquatic life would serve
adequately to maintain public health.
AQUATIC TOXICITIES OF ORGANIC CONSTITUENTS OF COAL CONVERSION EFFLUENTS
The toxic chemicals considered in this section are based on the
summary of organic constituents of coal conversion wastes from Section 4.
26
-------
•i
TABLE 13. SUMMARY OF ENVIRONMENTAL BEHAVIOR OF CLASSES OF ORGANIC COAL CONVERSION EFFLUENT CONSTITUENTS
Phenols
Monoaromatics
Polycyclic Aromatics
Aromatic Amines
Thiophenes
Acute
Toxicity
High
Moderate
High
Moderate
Moderate
Chronic
Effects
Low
Low
High
High+
High+
Wastewater
Removal
Efficiency
High
Moderate
Low
Low
Low
Microbial
Degradation
Rapid
Moderate
Slow
Slow
Slow
Bioaccumulation
Potential
Low
Low
High
Moderate
Moderate
Information
Available
Much
Moderate
Moderate
Little
Little
After Herbes, et^ a^. (10).
Insufficient information to support valid conclusions.
-------
TABLE 14. MINIMUM ACUTE TOXICITY EFFLUENTS (MATE's) AND ESTIMATED PERMISSIBLE
CONCENTRATIONS (EPC's) IN WATER FOR SOME CONSTITUENTS OF COAL
CONVERSION WASTEWATERS BASED ON HUMAN HEALTH CONSIDERATIONS*
Estimated Permissible
Compound
Aldehydes
benzaldehyde
Ketones
acetophenone
Carboxylic Acids
acetic acid
benzole acid
Amides
acetamide
Phenols
phenol"*"
cresols
ethylphenols
xylenols^
alkyl cresols
catechol
1,3-dihydroxybenzene
1,4-dihydroxybenzene
1,2,3-trihydroxybenzene
1-naphthol
2-naphthol
indanols
2-hydroxydibenzofuran
Substituted Benzene Compounds
biphenyl
tetrahydronaphthalene
Fused Polycyclic Hydrocarbons
naphthalene"1"
dimethylaphthalenes
acenaphthalene
anthracene"*"
phenanthrene"1"
methylphenanthrene
chrysene"*"
methylchrysenes
pyrene
dimethyIpyrenes
benzo (a) pyrene"1^
benzo(e) pyrene"*"
flourene**
1,2-benzoflourene
2,3-benzoflourene
flouranthene**
benzo(k)flouranthene
MATE
(yg/1)
8.8x105
6.1x105
3.8x105
2.1xl06
6.8x106
5
5
5
5
5
5
5
5
5
5
5
5
5
1.5x10^
2.0xl06
7.5x105
3.46x106
8.45x105
2.39x104
4.6xK>5
3.33xl04
2.69xl04
3.45x106
0.3
4.56x10^
1.4x106
1.6xl03
Concentrations (pg/l)
EPCwhl
1580
—
900
3700
—
675
780
—
360
640
720
—
—
—
—
—
—
—
36
3480
1785
—
II
855
—
—
—
61.5
™
2430
—
EPCwh2
520
—
345
1200
—
210
304
—
120
212
280
—
—
—
—
—
—
—
13.8
1640
690
—
II
280
—
__
—
—
20
—
800
__
EPCwhs
—
—
—
—
1
1
1
1
1
1
1
1
1
1
1
1
1
__
—
—
II
—
—
—
—
—
~~
EPCws
—
—
— —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
__
—
2170
—
1995
57
__
79.4
64.5
8333
7.5xlO-4
109
—
— —
(continued)
28
-------
TABLE 14 (continued)
Estimated Permissible
Compound
benzo(e)flouranthene
benzo(j)flouranthene+
benzo (b)f louranthene"*"
3-methylcholanthrene++
Aromatic Amines
aniline**
methyanilines#
dimethylanilines
Heterocyclic Nitrogen Compounds
pyridine
picolines
collidines
di & poly substituted pyridines
Fused 6 Member Heterocyclics
quinoline/isoquinoline
2-methyl quinoline
dimethyl quinoline
dimethyl isoquinoline
acridine
Pyrrole and Fused Ring Derivatives
pyrrole
indole+
methylindoles
carbazole
methylcarbazoles
Heterocyclic Oxygen Compounds
furan
benzofuran
hydroxybenzofuran
benzofuranol
Heterocyclic Sulfur Compounds
thiophene
methylthiophenes
dimethylthiophenes
MATE
(yg/D
1.4x104
9.8x104
1.34x104
56
3.5x105
1.65x103
3.75x105
2.25x105
5.34x105
1.04x106
4.1x105
2.36x105
3.31xl05
Concentrations (vtg/1)
EPCwhl
_t
—
—
—
675
780
900
535.5
960
1875
—
28.4
1500
EPCwh2 EPCwhs EPCys
__
231
31.5
0.14
262
304 — 4
345
207
316
616
—
140
492
1.35x106 2430
4.05xl04
1.65x105
6.8x105
3.4x105
75
1200
615
800
24
400
200
390
6.75x10^
3.4x105
120
615
40
200
*After Cleland and Kingsbury (11) .
+on NIOSH suspected carcinogen list
^insufficient evidence to rate carcinogenic potential, but has produced tumors
in test animals
++active carcinogen
**not known to be carcinogenic alone, but associated with compounds that are
##not known to be carcinogenic, but derivatives are
29
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TABLE 15. MINIMUM ACUTE TOXICITY EFFLUENTS (MATE's) AND ESTIMATED PERMISSIBLE
CONCENTRATIONS (EPC's) IN WATER FOR SOME CONSTITUENTS OF COAL
CONVERSION WASTEWATERS BASED ON ECOLOGICAL CONSIDERATIONS*
Estimated Permissible
Compound
acetic acid
Phenols
phenol
cresols
ethylphenol
xylenols
alkyl cresols
catechol
1 , 3-dihydroxybenzene
1, 4-dihydroxybenzene
1,2,3-trihydroxybenzene
1-naphthol
2-naphthol
indanols
2-hydroxydibenzofuran
Substituted Benzene Compounds
tetrahydronaphthalene
Fused Polycyclic Hydrocarbons
naphthalene
Aromatic Amines
aniline
Heterocyclic Nitrogen Compounds
pyridine
collidines
Fused 6 Member Ring Heterocyclics
quinoline/ isoquinoline
MATE
(yg/1)
IxlO3
500
500
500
500
500
500
500
500
500
500
500
500
500
1x103
100
1x103
1x10^
1x104
—
Concentrations (yg/1)
EPCWeI
500
500
50
—
700
—
—
—
—
—
—
—
—
—
500
50
500
5000
5000
—
EPCW62
1000
70
—
1000
—
800
—
—
—
—
—
—
—
—
1000
—
5000
—
500
EPGwes
100 (as phenolics)
100 (as phenolics)
100 (as phenolics)
100 (as phenolics)
100 (as phenolics)
100 (as phenolics)
100 (as phenolics)
100 (as phenolics)
100 (as phenolics)
100 (as phenolics)
100 (as phenolics)
100 (as phenolics)
100 (as phenolics)
—
—
—
—
—
—
kAfter Cleland and Kingsbury (11) ,
30
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TABLE 16. DEFINITIONS OF SUBCATEGORIES OF ESTIMATED PERMISSIBLE
CONCENTRATIONS (EPC's)
The EPC of a chemical in water derived from the assumption
that a maximum daily safe dosage to humans results from a
24-hour exposure to air containing the chemical, and that
the same dosage is permissible in the volume of drinking
water consumed in 24 hours.
The EPC of a chemical in water based on human health
considerations of the safe maximum body concentration and
the biological half-life of the substance.
EPCwhs - The EPC of a chemical in water corresponding to the most
stringent existing or proposed federal regulation or
criteria prescribing a water concentration for the chemical
based on human health considerations.
EPCWC - The EPC of a chemical in water based on the potential
carcinogenicity of the substance. The concentrations assume
a minimal risk dosage rather than a no-effect level.
The EPC of a chemical in water based on the lowest reported
LC5Q or TLm (median tolerance limit) for sensitive aquatic
species and assuming an application factor of 0.05.
The EPC of a chemical in water based on the lowest
concentration of the chemical reported to cause tainting in
fish flesh.
EPCwes - The EPC of a chemical substance corresponding to the most
stringent existing or proposed federal water criteria
established to protect aquatic life.
*After Cleland and Kingsbury (11).
31
-------
Toxicity data for a number of compounds are scant or wholly lacking. For
those compounds which have been studied, the majority of information is
derived from acute lethal toxicity tests on fish conducted with pure com-
pounds or simple mixtures. The potential impact of coal conversion waste-
water constituents on aquatic biota may be inferred from these studies,
but extrapolations to determine toxic effects of combined effluents may
prove meaningless. Although synergistic and antagonistic interactions
between components will certainly occur, to what extent they will affect
toxicity cannot currently be predicted from available data.
Phenols
The toxicity of phenols to aquatic organisms was recently reviewed
by the European Inland Fishery Advisory Commission (15). Phenol concen-
trations in the range of 4-56 mg/1 are acutely toxic to fish, and concen-
trations of 1-2 mg/1 may produce long-term damage. Cresols have been
studied less than phenol, and, of the three isomers, m-cresol is the least
toxic. Toxicity values reported for o- and p-cresol are inconsistent.
Xylenols are the least studied of the monohydric phenols, and no work has
been conducted on 2,3- or 2,6-xylenol. Few data exist for either dihydric
or polyphenols. Hydroquinone and naphthols are more toxic than phenol
(0.1-1.40 mg/1), but these compounds are usually found in much smaller
concentrations in coal conversion wastes. Sublethal responses of fish
exposed to phenols include weight loss, reduction of growth, decreased
sexual activity, alteration of reflexes, and histopathological anomalies.
The acute toxicity of several phenols to fish are presented in Table
17. Threshold concentrations of various phenolics to lower organisms are
summarized in Table 18. Generally, bacteria, algae, protozoa, crustaceans,
and molluscs are 10-100 times more resistant to phenol than fish. The
cladoceran, Daphnia, however, appears to be more sensitive than other
aquatic invertebrates.
Several papers not considered in the E.I.F.A.C. review should be
mentioned. Huang and Gloyna (18) studied the amount of chlorophyll
destruction sustained to the green algal, Chlorella pyrenoidosa, exposed
to a number of phenolic compounds. A 30 per cent reduction in chlorophyll
was observed in the presence of 100 mg/1 of phenol. Cresols were found
to further the reduction in chlorophyll over that observed for phenol,
but there were not significant differences among the cresol isomers.
Xylenols generally exhibited higher "toxicities" than cresols, but the
position of the substituent methyl groups did not significantly affect
the relative chlorophyll concentration. None of the xylenols showed any
damage to chlorophyll at concentrations less than 50 mg/1. "Phenol
coefficients" (the ratio of the destructive effect of a compound to that
of phenol) of o-cresol, m-cresol, p-cresol, catechol, resorcinol, and
hydroquinone were listed as 1.48, 1.36, 1.57, 0.74, 0.41, and 1.30,
respectively.
Oxygen consumption by the snail, Helisoma trivolvis, was significantly
reduced by exposure to 2 mg/1 of phenol (19). Similarly, life-long
exposure to 2.8, 8.2, 11.2, 16.3, and 22.4 mg/1 of phenol depressed oxygen
32
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TABLE 17. ACUTE TOXICITY OF SOME PHENOLS TO FISH
Compound Organism
phenol crucian carp
roach
tench
"trout" embryos
rainbow trout
rainbow trout
fathead minnow
fathead minnow
o-cresol crucian carp
roach
tench
"trout" embryos
m-cresol crucian carp
<
roach
tench
"trout" embryos
p-cresol crucian carp
roach
tench
"trout" embryos
fathead minnows
fathead minnows
2,4-xylenol crucian carp
tench
"trout" embryos
2,5-xylenol crucian carp
roach
tench
"trout" embryos
3,4-xylenol crucian carp
roach
tench
"trout" embryos
fathead minnows
3,5-xylenol crucian carp
tench
"trout" embryos
Concentration
(mg/1)
25
15
17
5
4.2-5.0
1.39
33
32
30
16
15
2
25
23
21
7
25
17
16
4
21
19
30
13
28
10
10
9
2
21
16
18
7
14
53
51
50
Response Tested
24-hr LC5Q
24-hr LCso
24-hr LCso
24-hr LCso
threshold
concentration
48-hr LC50
72-hr LCso
96-hr LCSO
24-hr LCso
24-hr LCso
24-hr LCso
24-hr LCso
24-hr LCso
24-hr LCso
24-hr LCso
24-hr LC5o
24-hr LC50
24-hr LCso
24-hr LCso
24-hr LCso
72-hr LCso
96-hr LCso
24-hr LC5o
24-hr LCso
24-hr LCso
24-hr LCso
24-hr LCSO
24-hr LC50
24-hr LCso
24-hr LCso
24-hr LC5Q
24-hr LCso
24-hr LCso
72-96 hr LC50
24-hr LC50
24-hr LCso
24-hr LCso
Reference
15
15
15
15
2
3
16
16
15
15
15
15
15
15
15
15
15
15
15
15
-L_y
16
15
15
15
15
15
15
15
15
15
15
15
15
16
15
15
15
33
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TABLE 18. THRESHOLD CONCENTRATIONS OF VARIOUS PHENOLICS TO LOWER
AQUATIC ORGANISMS (mg/1)*
Compound
phenol
o-cresol
m-cresol
p-cresol
3,4-xylenol
2,4-xylenol
2,5-xylenol
resorcinol
hydroquinone
pyrocatechol
quinone
Daphnia
(microcrustacean)
16.0
16.0
28.0
12.0
16.0
24.0
10.0
0.8
0.6
4.0
0.4
Scenedesmus
(alga)
40.0
40.0
40.0
6.0
40.0
40.0
40.0
60.0
4.0
6.0
6.0
Microregma
(protozoan)
30.0
50.0
20.0
10.0
10.0
70.0
50.0
40.0
2.0
6.0
2.0
E. Coli
(bacterium)
>1000
600
600
>1000
500
>100
>100
>1000
50
90
50
*After McKee and Wolf (17).
34
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uptake by the aquatic midge larva, Ghironomus attenuatus (20). These
data suggest that sublethal effects of phenol on invertebrates can
occur within the same concentration range that affect fish. Finally,
a 48-hr. LC^Q value of 1.28 mg/1 of resorcinol was recently reported for
Daphnia (21).
Aliphatic Acids
Information on the toxic effects of organic acids to aquatic
organisms is limited. Acute toxicity tests have been conducted with
several compounds, and results are summarized in Table 19. Although
comparisons are difficult due to the paucity of data, Daphnia and the
diatom, Nitzschia, appear to be more sensitive than the various fish
species tested.
Mattson, et al. (16) recently conducted acute toxicity tests with
fathead minnows, and reported 96-hr LCso's of 88 mg/1 for acetic acid,
97 mg/1 for adipic acid, 88 mg/1 for caproic acid, 205 mg/1 for oleic
acid, and 77 mg/1 for valeric acid. Sublethal responses of aquatic
organisms to organic acids have not been well studied, although green
sunfish were not repelled by 20 mg/1 of glacial acetic acid in preference-
avoidance trials (22).
Polynuclear Aromatic Hydrocarbons
Although polynuclear aromatic hydrocarbons (PAH's) will be present
in coal conversion effluents, little is known about the toxicity of these
compounds to aquatic organisms. Those data that are available have been
obtained primarily from oil spill studies. Extrapolation of toxicity data
from these studies to coal conversion effluents must be made cautiously.
The absence of data for specific polynuclear aromatic hydrocarbons
necessitates some consideration of the toxic effects of water-soluble
fractions of oils. A number of investigators have conducted toxicity
tests on water-soluble fractions of crude oils which contain PAH's, but
rarely have individual compounds within these fractions been characterized.
In general, water-soluble fractions of refined oils are more toxic than
water-soluble fractions of equivalent amounts of crude oils. The difference
in toxicity has been attributed to the higher percentage of boiling point,
low molecular weight aromatics found in refined oil. Naphthalenes,
methylnaphthalenes, and dimethylnaphthalenes have been specifically
implicated by several investigators (23-27). Soluble aromatic derivatives
of crude oil, in concentrations from 1-100 mg/1, can be expected to be
acutely lethal to most adult marine organisms. Larvae and juveniles are
usually much more sensitive, and may be eliminated by concentrations as
low as 0.1 mg/1 (28).
Despite an abundance of literature dealing with soluble fractions of
petroleum, the toxicity of specific PAH's are not well known. Acute
toxicity data from some PAH's are presented in Table 20. From these
data, it appears that algae are most resistant to acute poisoning, and
crustaceans are more sensitive than fish. A number of physiological and
behavioral responses of marine organisms exposed to oil and oil constituents
35
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TABLE 19. TDXICITIES OF SOME ORGANIC ACIDS TO AQUATIC ORGANISMS"
Compound
Formic Acid
Acetic Acid
Propionic Acid
Butyric Acid
Organism
Sewage Microorganisms
Lepomis macrochirus
L. macrochirus
L. macrochirus
L. macrochirus
Ictalurus punctatus
Carassius auratus
Semotilus atromaculatus
Gambusia affinis
Carp, Perch
Daphnia magna
Daphnia magna
Daphnia magna
Culex sp . , larvae
Nitzschia linearis
L. macrochirus
D. magna
Culex sp. , larvae
L. macrochirus
D. magna
Exposure
Time
24 hr
5 day
96 hr
24 hr
96 hr
72 hr
48 hr
24 hr
96 hr
8 hr
24 hr
24-72 hr
32 hr
48 hr
120 hr
24 hr
48 hr
48 hr
24 hr
48 hr
Concentration
' (mg/1)
175
550
75
100-1000
75
270 (by vol)
100
100-200
251
4.7 (by vol)
47
125
150
1500
74
188
50
1000
200
61
Toxicity
LCso
TC50
LCSO
LCso
LC50
LCSO
"killed some"
critical range
LCso
lethal
LCso
lethal
threshold of
immobilization
LC50
LC50
LCSO
LC50
LCso
LC50
*After Smith (7).
36
-------
TABLE 2Q. TOXICITY OF SOME POLYNUCLEAR AROMATIC HYDROCARBONS TO MARINE AND AQUATIC ORGANISMS
Compound
Naphthalene
1-Methylnaphthalene
2-Methylnaphthalene
Dimethylnaphthalene
1,6-dimethylnaphthalene
Anthracene
Phenanthrene
Organism
Chlorella yulgaris
Chlamydomonas angulosa
Chlamydomonas angulosa
Paleomonetes pugio
Penaeus aztecus
Sheepshead Minnow
Silver Salmon
Mosquito Fish
Mosquito Fish
Mosquito Fish
Sheepshead Minnow
Fathead Minnow
Paleomonetes pugio
Penaeus Aztecus
Sheepshead Minnow
Paleomonetes pugio
Penaeus aztecus
Sheepshead Minnow
Sea Lamprey
Rainbow Trout
Bluegill
Sea Lamprey
Chinook & Coho Salmon
Rainbow Trout
Bluegill
Concentration
(mg/1)
27
3.5
3.5
2.6
2.5
2.4
1.8-3.2
220
165
150
3.4
9.0
1.7
0.7
2.0
0.7
0.08
5.1
5
5
5
10
5
5
Response
24-hr. LC5Q
61% killed in 4 days
(open flasks)
97% killed in 4 days
(stoppered flasks)
24-hr. LC5Q
24-hr. LC5Q
24-hr. LC5Q
72-hr, critical cone.
24-hr. LC50
48-hr. LC5Q
96-hr. LC5Q
24-hr. LC5Q
96- hr. LC50
24-hr. LC5Q
24-hr. LC5Q
24-hr.
24-hr. LC50
24-hr. LC50
24-hr. LC5Q
no effect*
no effect*
no effect*
no effect*
no effect*
lethal in 5-hr.
lethal in 5-hr.
Reference
29
25
25
30
30
30
31
33
33
33
30
16
30
30
30
30
30
30
32
32
32
32
34
32
32
(continued)
-------
TABLE 20. (continued)
oo
Compound
Organism
Concentration
(mg/1)
Response
Reference
Chrysene
Flour ene
Flouranthene
3-Methylcholanthrene
Pyrene
3, 4-Benzopyrene
Rainbow Trout
Bluegill
Sea Lamprey
Chinook & Coho Salmon
Sea Lamprey
Sea Lamprey
Chinook & Coho Salmon
Chinook Salmon
Coho Salmon
Chinook & Coho Salmon
5
5
5
10
5
5
10
10
10
10
no effect*
no effect*
no effect*
no effect*
no effect*
no effect*
no effect*
loss of equilibrium in
5-9 hr. , lethal in
9-13 hr.
lethal in 13-17 hr.
no effect*
32
32
32
34
32
32
34
34
34
34
only concentration tested
-------
have been documented, but the extent to which PAH's play a role is not
clear. Various sublethal responses to petroleum products have been
demonstrated including effects on respiration (35,36), feeding (37,38),
molting (39), growth (40), carbon flux (41), locomotor activity (42,43).
enzyme activity (44,45), chemotactic behavior (46,47), and histopathology
(48,49).
A number of PAH's which have been identified or are anticipated to
occur in coal conversion wastes will contribute to acute toxicity. Mixtures
of various PAH's, and PAH's and other organic compounds, may prove to be
more toxic than individual compounds since combined naphthalenes have been
shown to be more toxic than either naphthalene, methylnaphthalene, or
dimethylnaphthalene alone (27). PAH-induced acute toxicity is of concern,
but a more serious threat to aquatic environments may be posed by the
release of slightly soluble, high molecular weight, multi-ring compounds.
Included in this group are a number of known carcinogenic and mutagenic
compounds, such as benzopyrenes and methylcholanthrenes. Coal conversion
wastes are expected to contain only minuted amounts of these compounds,
but they do not appear to be readily biodegradable and may be difficult to
remove by waste treatment. Consequently, they may bioaccumulate in a
number of aquatic organisms (including edible fish and shellfish) and
thereby become a source of carcinogens to man. The detection of
carcinogenic substances in fish would almost certainly lead to a ban
on both commercial and recreational fishing in affected areas.
While the production of PAH-induced cancers in aquatic organisms
has not been experimentally verified, the occurrence of tumors and
neoplasms has been associated with PAH's in several instances. Analysis
of water samples from the Fox River in Illinois verified the presence
of several aromatic compounds, including 0.01 mg/1 benzanthracene, and
0.1 mg/1 each of naphthalene, toluene, and benzene (50). The frequency
of various neoplasms in fish collected from contaminated water was 4.38%,
compared to 1.03% in fish from control waters. Papilliform tumors and
other lethal malformations have been produced in planaria exposed to
3-methylcholanthrene and benzo(a)-pyrene (51). Uncontrolled growth of
ovicells has been induced in the estuarine bryozoan, Schizoporella
unicornis, by placing normal colonies near coal tar derivatives in an
estuary. It was suggested that the growth was stimulated by several
PAH's present in coal tar (1,2,5,6-dibenzanthracene, benzo(a)pyrene,
and methylcholanthrene) (52). Although abnormal growths are usually
associated with animals, multi-ring compounds have been implicated as
the cause of cancer-like growths in algae as well (53,54).
Nitrogen- and Sulfur-Containing Compounds
Toxicity of the nitrogen- and sulfur-substituted aromatics were
recently reviewed (55) and are the least understood constituents of coal
conversion wastewaters. Aryl amines and thiophenes are more soluble
in water than the PAH's, and may therefore occur at greater concentrations
in coal conversion effluents. The potential for bioaccumulation and food
chain magnification are marked, and the relative hazards to aquatic biota
may equal or exceed those of the PAH's. A summary of acute toxicity data
for several nitrogen containing compounds is given in Table 21. Similar
data for sulfur substituted compounds are virtually non-existent. Thiophene
39
-------
TABLE 21. TOXICITY OF NITROGEN CONTAINING COMPOUNDS TO AQUATIC ORGANISMS*
Concentration
Compound
Aniline
Indole
Isoquinoline
Pyridine
Organism
Fathead Minnow
Goldfish
Trout
Sunfish
Fish
Daphnia
Daphnia
Trout
Bluegill
Sea Lamprey
Sunfish
Perch
Mosquito Fish
Fish
Perch
Yearling Trout
Perch
Carp
Bream
Bleak
Fish
Daphnia
Fish
(mg/1)
200
1000
100
1020-1120
250
279
0.4
5.0
5.0
5.0
65
100
1300-1350
1000
1000
400
200
200
180
160
100
40
15
Response
96-hr. LC5Q
96-hr. LC5Q
96-hr. LCso
lethal in 1 hr.
lethal
lethal
48-hr. LC5Q
lethal in 10 hr.
no effect in 24 hr.
no effect in 24 hr.
lethal in 1 hr.
lethal in 1 hr.
96-hr. LC5Q
threshold effect
lethal
toxic limit
no effect
threshold toxicity
threshold toxicity
threshold toxicity
threshold toxicity
threshold toxicity
toxic action on
central nervous system
Quinaldine
Quinoline
Trout
Sunfish
Perch
Perch
Trout
Bluegill
Fish
Trout Yearlings
Bleak
Bream
Carp
Daphnia
Ciliates
Fathead Minnow**
5.0
52-50
30-50
30
5.0
5.0
7.5
7.5-10
10
10
10
52
750
46
lethal in 1 hr.
lethal in 1 hr.
lethal in 1 hr.
lethal
lethal in 14 hr.
lethal in 4 hr.
lethal
lethal in 1 hr.
96-hr. LC5Q
96-hr. LC5Q
96-hr. LC5Q
at 23°C
lethal
24,48,72,96-hr. LC5Q
"After Wilkes (55).
From Mattson, et al. (16).
**
40
-------
is approximately 33% more toxic to sunfish than is benzene, and thiophene
and 2-methylthiophene are more toxic to mammals than their benzene analogs.
From these correlations, it is assumed that the higher molecular weight
thiophene compounds may also be more toxic than the corresponding PAH
compounds. No information is available regarding the carcinogenic and
mutagenic effects of heterocyclic compounds, potential interactions between
heterocyclics and other classes of organic compounds, or chronic effects
°f trace levels of heterocyclics to aquatic organisms. However, the
presence of nitrogen or sulfur heteroatoms in PAH structures has been
noted to either intensify or lessen carcinogenicity. Several heterocyclic
analogs of phenanthrene (acridine, carbazole, and thiophene derivatives)
have also been proven to be carcinogenic to mammals.
RESEARCH NEEDS
More complete information about the aquatic impact of coal conversion
effluents is needed in three major areas:
1. determination of acute lethal toxicity values for those
compounds for which information is lacking;
2. analysis of interactions among organic compounds which
occur together in coal conversion effluents; and
3. development of chronic toxicity data for coal conversion
effluents and constituents in both laboratory and
ecosystem populations.
Before research in the latter two areas can be conducted, however, basic
acute toxicity data for the constituents must be accumulated. Particular
attention should be given to those components which are not readily
biodegradable and are not easily removed by waste treatment. Such
components are likely to be persistent in aquatic systems.
If the entire aquatic community is to be protected, pollutant
toxicity must be determined for at least three components of the aquatic
food web. The most sensitive group of organisms must then be identified
(56,57). The realization that the elimination of lower organisms may
have serious environmental consequences has led to increased reliance on
invertebrates and algae, as well as fish, for toxicity testing. Several
aquatic species have become widely accepted as bioassay organisms, including
the fathead minnow (Pimephales promelas), cladocerans (Daphnia magna and
D. pulex). and an alga (Selenastrum capricornutum), and standard procedures
for acute toxicity testing are available (58,59).
Although acute toxicity tests can identify specific pollutants of
immediate concern and may be used to determine "safe" levels in receiving
waters by appropriate application factors (9), it is impossible to predict
safe limits for complex effluents. The degree of interaction that occurs
in complex wastes is unknown. Further, the effluents of any two conversion
plants may differ, and a compound common to both waste streams could exhibit
different toxic behavior in each. Unfortunately, the limited availability
of coal conversion effluents at present precludes research on the toxic
41
-------
effects of composite effluents.
Therefore, in order to assess the aquatic impact of coal conversion
wastewaters, the following approach has been adopted. Aquatic bioassay
tests will be conducted to develop acute toxicity data for selected
wastewater constituents on the three test organisms cited: Pimephales
promelas, Daphnia pulex, and Selenastrum capricornutum. The constituents
to be tested will be those which are non-biodegradable and would tend to
persist in waters receiving biologically treated coal conversion wastewater.
Following collection of such component toxicity data, treated effluents
from both synthetic and real composite samples will be subjected to
similar tests. The results of the component studies will be used to help
interpret the results from the composite tests. While acute toxicity data
for the organic components cannot be used to assess chronic effects of
coal conversion wastes, such data should provide a reasonable preliminary
assessment of toxicity problems anticipated from coal conversion wastewaters.
42
-------
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47
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SECTION 6
MICROBIAL DEGRADATION OF ORGANIC CONSTITUENTS IN
COAL CONVERSION WASTEWATERS
In this section, a literature review of the biological degradability
of constituents from coal conversion processes is presented, along with
the results of some preliminary biodegradation experiments performed
during this first phase of our study. The microbiological literature
has been reviewed to determine microbial pathways by which phenols, N-
containing aromatics, and polynuclear aromatic hydrocarbons are degraded.
The majority of the research work on microbial degradation of these
organic compounds and the identification of metabolic pathways has been
done with pure cultures and single substrates, under highly-controlled
laboratory conditions. The microbial cultures employed were often
maintained and manipulated solely for the purpose of degrading a particular
substrate. It is therefore important to recognize that the degradation
of a compound under these conditions does not imply that it will be
readily biodegradable under natural or waste treatment conditions.
Lack of information as to degradation patterns or pathways does
not necessarily mean that the compound is not biodegradable, as many
compounds identified in coal conversion wastewaters have not been studied.
For some compounds which pose particular hazards to man, such as the
carcinogenic polynuclear aromatic hydrocarbons, attention has been
directed to mammalian metabolism rather than microbial degradation.
Nevertheless, such a review does provide a starting point in evaluating
the biodegradability of organic constituents under real, environmental
conditions.
LITERATURE REVIEW
Phenol and Other Monoaromatic Hydrocarbons
Coal conversion effluents contain a large number and variety of
organic components as discussed and illustrated previously in Section 5.
Of the many compounds that have been reported as constituents of coal
conversion effluents, the microbial degradation of only one class of
these compounds, the phenolics, has been extensively investigated.
However, review of this work provides information about the microbial
degradation of aromatic compounds in general, since phenols are the
major intermediates in the degradation of aromatics, i.e., they are the
substrates for ring fission enzymes. Therefore, an understanding of the
metabolism of phenols is basic to the study of the degradation of other
aromatic compounds. Additionally, phenolic compounds comprise the major
portion of the total organic carbon content of coal conversion effluents.
Microbial Pathway Studies—
Many bacteria and fungi can utilize aromatic hydrocarbons as a sole
source of carbon and energy. Specialized metabolic pathways convert
initial aromatic substrates to aliphatic cellular intermediary metabolites.
Gibson (1) has recently confirmed that the initial reaction in the
48
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bacterial oxidation of aromatic hydrocarbons is the formation of cis-
dihydrodiols. These compounds then undergo further oxidation to yield
dihydric phenols which are substrates for ring fission enzymes. This
process has been demonstrated for compounds ranging in size from benzene
to benzo(a)pyrene.
In general, the metabolism of benzenoid compounds is dependent on the
presence of molecular oxygen. Oxidative ring cleavages, along with most
oxidation steps in the initial sequences that converge on diphenols, are
mediated by oxygenases not deoxygenases (2). While molecular oxygen acts
as a terminal electron acceptor, it is also a specific reactant with those
enzymes which catalyze the introduction of hydroxyl groups and the fission
of suitably hydroxylated rings. Therefore, such pathways are strictly
aerobic since, even though some substances such as nitrate may fulfill the
role of electron acceptor, they are not reactive with oxygenases (3). Some
exceptions to this general condition do exist. For example, some hetero-
cyclic ring systems undergo hydroxylations in which water serves as the
source of the hydroxyl group (4). Also, water supplies a hydroxyl group
for the anaerobic photometabolism of benzoic acid by Rhodopseudomonas
palustris (5).
Another general condition for microbial degradation of aromatics is
that in order for ring cleavage to occur, the primary substrate must
initially be converted to either an ortho or para dihydric phenol. Two
of the most important of these compounds are catechol and protocatechuic
acid, both ortho phenols. Figure 1 shows initial sequences for bacterial
metabolism of various substrates that converge on catechol. Compounds
related to catechol which also serve as intermediate ring fission substrates
are 3-methylcatechol (7), 4-methylcatechol (8), and 1,2-dihydroxynaphthalene
(9).
Initial metabolism of m- and p-cresols along with other benzenoid
compounds may result in another ortho dihydric phenol, protocatechuic
acid. Figure 2 illustrates the convergence of some aromatic hydrocarbons
on this ring fission substrate. Another frequently encountered acidic
fission substrate is 2,3-dihydroxybenzoic acid (10).
The third important ring cleavage substrate is gentisic acid. This
is a para-dihydric phenol formed from such primary substrates as g-naphthol
(see Figure 3). A less common para-dihydric phenol is hydroquinone (11).
The importance of the position of the two hydroxyl groups on the ring
should not be overlooked. For example, in the metabolism of resorcinol, a
meta-dihydric phenol, ring fission does not occur until the compound is
hydroxylated to form a 1,2,4-trihydric phenol (12,13).
The modification of a substituent group may or may not occur before
ring cleavage depending on bacterial species, nature of the primary
substrate and position on the ring relative to other substituents. In
the case of the methyl group, some species of bacteria hydroxylate the
nucleus of cresols leaving the methyl group intact (8), while others
oxidize the methyl group initially to a carboxyl group (14). In the
former case the fission substrate is then a methyl-catechol, whereas in
the latter case the intermediate formed is either gentisic or protocatechuic
49
-------
CHOHCOOH
CH,
1,-MuideUte Toluane
COCOOH
CH]OH
Benzoylforaiate Benzyl alcohol
\ CHO *
COOH
Benzoata
COOH HO COOH COOH
OH ^S^ ^OH
I
Balicylata
Anthracene
,CH,CHNH,(X)OH
I.-Kynunaiua
OH
Anthnnilaia
OH
CAlflECHOL Phenol
OH
Figure 1. Initial reactions in the bacterial degradation of various
compounds that converge on catechol. (From Stanier and Ornston (6).)
Reproduced with permission from Advances in Microbial Physiology,
Academic Press Inc. (London) Ltd.
50
-------
CHOHCOOH
OH
p-Hydroxy-L-mandelate
COCOOH
OH
COOH
HO" \X^ ^OH
OH
Shikimate
HO COOH
HO ^V^ ^OH
OH
Quinate
COOH
COOH
Benzoata
COOH
\
OH
p-Hydroxybenzoate
O*'^^ ^OH
OH
COOH
\ /
HO COOH
O^\X^ ^OH
OH
COOH
COOH
m-Hydroxybenzoate
SOH
OH
PROTOCATECHUATE
^OCH3
OH
VaniUate
Figure 2. Initial reactions in the bacterial degradation of various
compounds that converge on protocatechuate. (From Stanier and
Ornston (6).) Reproduced with permission from Advances in Microbial
Physiology, Academic Press Inc. (London) Ltd.
51
-------
Salicylic a.
Figure 3. Initial reactions in the bacterial degradation of various
compounds that converge on gentisic acid. (From Chapman (18).)
Reproduced fron Degradation of Synthetic Organic Molecules in the
Biosphere (1?72), Page 22, with the permission of the National Academy
of Sciences, .rasping ton, B.C.
52
-------
aci(?' . The dimethylphenols (xylenols) act similarly. Depending on the
position of the methyl groups on the ring, metabolism results in either
protocatechuic acid or a methylgentisic acid (14,15).
Alkyl side chains possessing two or more carbons may also undergo
modification. Carboxylic acids are formed by the oxidation of the
terminal methyl group. The larger carboxylic alkyl chains may then
undergo $-oxidation, but sometimes may remain intact on the ring cleavage
substrates as shown in Figure 4. Generally, carboxyl groups remain
intact prior to ring cleavage, but they may be eliminated as in the
metabolism of benzoic acid to catechol (17). Chapman (18) notes that
alkoxyl groups are usually dealkylated initially to form an aldehyde and
the parent phenol.
Once the primary substrate has been converted to one of the ring
fission substrates, cleavage can then occur. Bacteria employ two different
modes of enzymatic ring cleavage, known respectively as ortho and meta
fission. Figure 5 shows both types of fission for catechol and
protocatechuic acid. Ortho fission is the splitting of the bond
between two carbon atoms bearing hydroxyl groups. This results in the
formation of dicarboxylic acids. The other pathway, meta fission, leads
to either an aldo-acid or keto-acid by cleavage of a carbon-carbon bond
where only one carbon bears a hydroxyl group. Usually, a particular
microbial species employs only one method of ring fission for a certain
primary substrate (6). However, catechol is an exception. Some bacteria
can metabolize catechol via both ortho and meta fission pathways (19).
The method of ring fission varies with species, structure of the dihydric
phenol, and the substrate upon which the microbial culture has been
maintained. This last condition has been demonstrated by Hopper and
Taylor (20) for the cresol isomers. When bacteria were grown on p-
cresol, p-cresol was degraded by the ortho-fission pathway, but when the
same culture had been maintained on m-cresol, p-cresol was degraded via
meta-fission.
Figure 6 shows the fission pathway for gentisic acid. Fission
occurs at the carbon-carbon bond where one carbon bears a hydroxyl group
and the other carbon bears the carboxyl substituent.
The trihydric ring fission substrate, 1,2,4-trihydroxybenzene,
found in the degradation of resorcinol, undergoes ortho-fission (11)
with the ultimate products being acetic and formic acids. Other trihydric
phenols undergo meta-fission.
If all of the information presented above is applied to the various
phenolic compounds found in coal conversion wastewaters, certain patterns
emerge. Table 22 presents the relevant metabolic pathways for selected
phenolic constituents.
Figure 7 is a general scheme for the bacterial degradation of
substituted phenols. The ultimate ring fission products of most phenolics
undergo fatty acid metabolism or enter the tricarboxylic acid cycle of
the microorganisms.
53
-------
Alky!benzene
Phenylpropionic
Acid
m-Hydroxyphenyl
propionic Acid
Ln
iv"\YOH
Ring Cleavage
2,3-Dihydroxyohenyl
Drooionic Acid
Figure 4. Example of an aromatic compound possessing an alkyl side chain v/hich remains intact prior to
ring cleavage. (From Van der Linden and Thijsse (16).)
-------
-o,c
OH
Frotocatechuate
Ui
CHO
at-Hydroxy-y-carboxy-
muconic aemialdehyde
orCto pathway.
.auto pathway
OB.
/3-Carboxy-CM,ct»-muconate ew.oM-Muoonato a-Hydroxy muconic semialdehyde
^-Ketoadipate
Formate and 2 pyruvata
Formate,
acetaldehyde
and pyruvate
Succinate
and acetyl-CoA
Figure 5. Ortho and meta fission pathways for the dissimilation of protocatcchuate and catcchol.
(From Stanicr and Ornston (6).) Reproduced -rith p-.mJ.G.3lo-i fron Advances in Iltgrsblal Physiology,
Academic Press Inc. (London) Ltd.
-------
OH
Ui
CO2H
H
(a) Gentisate
H
OH
(b) 3-Methylgentisate
OH
OH
Pyruvate
Acetyl-CoA
GSH
H02C
H2O pyruvate HO2C
C02H ^3 >
OH
II
CO2H
CB3—O—OH
III
!O-SCoA
V
succinyl-CoA
*-r—
succinate
/
/ H20
L-Malate
C02H
CH3—C-OH
CH2
CO2H
IV
Figure 6. Bacterial metabolism of gcntisic acids. (From Dagley (21).)
Reproduced with permission from Advances in Microbial PHysiglogy,
Academic Press Inc. (London) Ltd.
-------
TABLE 22. PROPOSED METABOLIC PATHWAYS FOR THE
MICROBIAL DEGRADATION OF SELECTED
PHENOLIC COMPOUNDS.
OH
Phenol
OH
OH
Catechol
Figure 5
"Ortho" fission
CM,
m-Cresol
COOH
' Figure 6
Of/
Gentisic Acid
H
•OH
OH
Protocatechuic Acid
Figure 5
"Meta" fission
(continued)
-------
TABLE 22. (continued)
m-Cresol
3-Methylcatechol
Figure 5
"^ "Meta" fission
oo
CM,
o-Cresol
OH
OH
3-Methylcatechol
Figure -5
"Meta" fission
CH,
o//
p-Cresol
Coo/-/
coo//
OH
p-Hydroxybenzoic Acid
o//
o//
Protocatechuic Acid
Figure •$
"Ortho" fission
C continued)
-------
TABLE 22. (continued)
OH
p-Cresol
CU3
Otf
OH
4-Methylcatechol
Figure 5
"Meta" fission
I
C-
1
o//
Substituted Catechols
/. -C - Coo/V
)i
o
- C =
(continued)
-------
TABLE 22. (continued)
CT<
O
ort
Oh'
c//,
coof/
2,4-Xylenol
4-Hydroxy-3-
Methylbenzoate
4-Hydroxyiso-
phthalic Acid
COOA/
Protocatechuic Acid
Acid
Figure 5
CH.
/4C
-^Figure 6
2,5-Xylenol
3-Hydroxy-4-
methylbenzoate
o/y
4-Methyl-
gentisic Acid
(continued)
-------
TABLE 22. (continued)
Hf.
3,5-Xylenol
Figure 6
coo H
3-Hydroxy-5-
Methylbenzoate
o//
3-Methyl-
gentisic Acid
Resoreino!
V
"7
o//
Figure 5
"Meta" fission
2-HydPOxyhydroquinone
OH
Hydro quinone
oH
Figure 5
"Meta" fission
2-Hydroxyhydro quinone
(continued)
-------
TABLE 22. (continued)
Orcinol
//o.
2,3,5-Trlhydroxy-
toluene
Figure 5
"Meta" fission
l-o
Benzoic
Acid
coo//
m-Hydroxy-
benzoic Acid
V
X
Protocatechuic-
Acid
Figure 5
(continued)
-------
TABLE 22. (continued)
/^G>OC
v
p-Hydroxybenzoic
Acid
Protocatechuic
Acid
Figure 5 .
"Ortho" fission
OJ
//o
COO//
m-Hydroxybenzoic
Acid
//o
COo//
Figure 6
Gentisic Acid
(continued)
-------
TABLE 22. (continued)
b-Naphthol
OH
ON
HO
O
H
-M
COOH
OH
Figure 6
Gentisic
Acid
-------
yqr^yy*. 5^r_^^.^r
HCTHn.-5-M£THTL- H
Figure 7. General reaction scheme for bacterial degradation of substituted phenols. (From
Chapman (18).) Reproduced from Degradation of Synthetic Organic I-olacules in the Biosphere
(1972), page 46, with the permission of the National Academy of Sciences, Washington, D.C.
-------
Metabolism by Mixed Cultures—
The metabolic pathway studies described above were carried out with
pure cultures of microorganisms under controlled laboratory conditions.
For the most part, these studies were conducted in order to discover the
enzymes and mechanism by which microorganisms metabolize aromatic compounds
for energy and growth. However, with respect to biological treatment of
wastewaters containing these compounds, it is necessary to focus attention
on mixed microbial communities, such as soil, sewage and activated
sludge. Furthermore, the rate at which the substrate is metabolized
must be considered.
Many of the data that exist on the biodegradability of phenolics in
mixed cultures in wastewaters are based on oxygen uptake measurements.
Early investigators studying biodegradability used the standard BOD test.
A summary of this type of data for a large number of pure organic compounds
included many phenols (22). The majority of the studies were done with
unacclimated sewage as seed. Under these conditions the data revealed
that phenol at concentrations below 500 mg/1 was readily degraded.
Ortho and meta cresol were degraded at approximately the same rate as
phenol, as were a- and g-naphthol. Para-cresol and 3,4-xylenol gave
somewhat lower oxygen demands and the BOD's of hydroquinone and 3,5-
xylenol were only one-half that of phenol after five days.
Respirometric studies with acclimated activated sludge demonstrate
the similar behavior of compounds of similar chemical structures, and
the ability of microorganisms adapted to a given substrate to oxidize
related compounds. The data of McKinney, Tomlinson and Wilcox (23) show
that organisms acclimated to phenol, o-cresol or m-cresol metabolized
phenol, the three cresol isomers, benzoic acid and p-hydroxybenzoic acid
to approximately 33% of their ThOD (theoretical oxygen demand) in
twelve hours. However, the phenol-acclimated sludge oxidized catechol
to only 13% of its ThOD, while o-cresol and m-cresol-acclimated sludges
metabolized catechol to the same extent as the other compounds (33% of
ThOD). In the phenol-acclimated system, cresols were oxidized to about
the same extent as phenol. The 3,4- and 2,4- and 2,6 and 3,5-methyl
substituted phenols showed progressively less oxidation than phenol,
indicating the importance of substituent position on the ring.
These results were later verified by a major study of the decomposition
of phenolic compounds by phenol-adapted bacteria (24). In addition to
respiration measurements, chemical analysis for residual substrate was
also performed. Some of the results of the study are presented in Table
23 and Figures 8a and 8b. The data indicate that phenol itself is
immediately and rapidly degraded and that dihydric phenols are oxidized
to the same extent as phenol. The presence of more than two hydroxyl
groups on the ring (e.g., phloroglucinol) increases resistance to degradation,
The addition of one methyl group (cresols) appeared to stimulate total
oxygen uptake for ortho and meta cresol. Total oxygen uptake for p-
cresol was the same as that for phenol although there was a rapid initial
uptake. Again, the effect of position of substitution on the ring was
illustrated by the dimethylphenols. Nitro-, chloro-substituted, and
trihydric phenols were relatively resistant to oxidation.
66
-------
TABLE 23. OXIDATION AND REMOVAL OF VARIOUS
PHENOLIC COMPOUNDS BY PHENOL-
ACCLIMATED BACTERIA. (AFTER
TABAK, et al. (24).)
Test compound
Phenol
Phenol
Phenol
Catechol
Resorcinol
Quinol
Phloroglucinol
-wi-Chlorophenol
p-Chlorophenol
2 4-Dichlorophenol
2 6-Dichlorophenol . .
2,4,6-Trichlorophenol. . .
w-Cresol
•p-Cresol
2 6-Dimethylphenol
3 5-Dimethylphenol .
2 4-Diinethylphenol
3 4-lDimethylphenol
Orcinol
Thymol
6-Chloro-wi-cresol
6-Chioro-2Tinethylphenol
4-Chloro-2-methylphenol
4-Chloro-3-methylphenol
Tft-Nitrophenol
2 4-Dinitrophenol
2 6-Dinitrophenol . .
2,4,6-Trinitrophenol ....
4,6-Dinitro-o-cresol. . . .
2,4,6-Trinitroresoreinol .
2,4,6-Trinitro-m-cresol. .
4-Chloro-2-nitrophenol. .
2-Chloro-4-nitrophenoI . .
2 , 6-Dichloro-4-nitro-
phenol
wi-Dinitrobenzene . . .
p-Dinitrobenzene .-
#z-Nitroaniline
2 4-Dinitroaniline
TO-Nitrobenzaldehyde —
3,5-Dinitrobenzoic acid.
Test concn
Initial
ppm
100
80
60
100
100
100
60
100
100
60
100
100
100
100
100
100
100
100
100
100
100
80
80
80
60
100
100
100
60
60
100
100
60
60
100
60
100
100
100
100
100
100
100
Loss
ppm
99
79
59
97
98
86
3
50
66
18
35 '
70
97
97
97
69
37
81
90
36
44
51
37
50
46
49
39
32
19
8
28
60
13
8
64
7
9
25
20
31
39
27
13
Amt of Ot
consumed*
(endogenous
corrected)
lilUers
319
252
186
255
252
149
12
66
80
46
39
56
417
457
306
40
70
126
189
72
48
81
66
90
113
48
65
54
66.
51
22
31
6
14
123
51
35
42
32
70
53
38
48
* Baaed on 180 min results
67
-------
CO
I I I I I 1
CONCENTRATION OF UNDESGNATED COMPOUNDS OOppm
CONCENTRATION OF ALL COMPOUNDS lOOppffl
^——-
-•-CRESOL
Figure 8a. Oxidation of dihydric phenolo.
(From Tabak, jit al. (24) . )
Figure 8b. Oxidation of crcsols and
other methylphenol derivatives.
(From Tabak, .et al. (24).)
-------
By monitoring the disappearance of substituted benzenes, Alexander
and Lustigman (25) observed the effect of chemical structure on biode-
gradability. Although a mixed population of soil microorganisms was
used, results were similar to those obtained in the previous work with
activated sludge. The presence of a chlorine atom in any position
retarded degradation significantly. The amino group inhibited degradation
only when in the meta position. Addition of one methyl group had no effect
and the addition of a methoxy group to phenol inhibited degradation only
when in the meta position.
Alexander and Lustigman (25) also noted that for some apparently
resistant compounds, degradation could be enhanced by the addition of an
available (supplemental) carbon source such as glucose. Some microorganisms
are capable of degrading a compound which they are unable to utilize for
growth. Such a situation was also encountered in a similar study of the
biodegradation of phenols (26). This phenomenon, known as co-metabolism,
has been observed frequently for a variety of species and substrates
although it is often overlooked (27). Co-metabolism has been shown to
occur not only in pure laboratory cultures, but also by naturally-
occurring mixed populations (28). In degradation studies, the use of
gas chromatography can detect products of co-metabolism as well as the
disappearance of the compound of interest.
Summary—
As indicated in the above discussion, there is a significant body
of literature available concerning the microbial degradation of phenols,
especially in pure cultures of microorganisms and in single-substrate
systems. This is especially true for both mono- and dihydric phenols.
Less information is available, however, with regard to the biodegradability
of the more highly substituted phenols, and the biodegradation of specific
phenolic constituents in mixtures of phenolic compounds. Furthermore,
little information is available regarding the level at which these
phenolic compounds become inhibitory to microbial degradation, and the
rates at which degradation takes place.
Nitrogen-Containing Aromatic Compounds
Microbial Pathway Studies—
The literature dealing with metabolic pathways for the degradation
by microorganisms of nitrogen-containing substances such as pyridine,
quinoline, and aniline is incomplete. Ultimate degradation has been
assumed because such compounds are not found to accumulate to any
degree in the soil. Microbial isolates from soil that can grow with
pyridine as the sole source of carbon, nitrogen and energy are usually
members of the actinomycetes. Other types of isolates from soil and
sewage, grown on pyridine, include species of Agrobacterium, Achromobacter,
Nocardia, Bacillus, and a possible Pseudomonas.
The nitrogen atom of the pyridine ring is electronegative in relation
to the carbon atoms of the ring. This results in an asymmetric molecule
with a degree of polarity quite different from the benzene ring. Pyridine
is relatively electron deficient and will resist electrophilic substitutions
especially at the 2,.4, and 6 carbon positions, making hydroxylations at
69
-------
these positions unlikely. The nitrogen atom has the least influence on
the C-3 position and chemical reactions of 3-hydroxypyridine resemble
those of phenol (29). The presence of a hydroxyl group on the ring makes
the ring more susceptible to further electrophilic attack, particularly
in the sites ortho and para to the hydroxyl group. On the other hand,
pyridines can become even more resistant to electrophilic attack in
acidic aqueous solution. The nitrogen atom possesses a pair of electrons
by which it can accept a proton to form the stable pyridinium ion. This
results in the distribution of a positive charge over all the carbon atoms
in the ring.
Quinolines and isoquinolines are the most common of the pyridines
fused to benzene rings. These compounds show largely the same reactivity
as pyridine (30).
While there is no single definitive pathway for the dissimilation
of pyridine by all microorganisms, the appearance of the pyridine N-
atom as NH3 has been confirmed (29). The fate of the carbon-nitrogen
skeleton and the nature of the initial metabolic reactions are less clear.
It has been reported that under certain conditions, the degradation
of pyridine and its three monohydroxy isomers by microorganisms isolated
from soil and sewage results in the accumulation of pyridine-diols (29).
However, of these diols, only the 3,4-isomer was even slightly metabolized
further. According to the sequential induction theory, this casts some
doubt on the role of the diols as major intermediates in the degradation
of pyridines. Later studies (31,32) have shown the degradation of 3,4-
and 2,5-pyridine-diols by species of Agrobacterium and Achromobacter.
Pyridine-3,4-diol is thought to be an intermediate in the degradation of
4-hydroxypyridine, and pyridine-2,5-diol is produced from both 2- and 3-
hydroxypyridine. Watson ^t al. (31), proposed the pathway shown in
Figure 9 for microbial degradation of 3,4-dihydroxypyridine. The proposed
pathway for pyridine-2,5-diol (32) was based on the maleate pathway (33)
and is shown in Figure 10.
More recently, Watson and Cain (34) proposed two distinct metabolic
pathways for the microbial dissimilation of pyridine itself. Two micro-
organisms, one Nocardia and one Bacillus, were isolated from soil and were
able to utilize pyridine as the sole source of carbon, nitrogen and energy.
Analysis of culture filtrates showed no evidence that UV-absorbing products
accumulated during degradation. This would indicate the lack of any stable
aromatic product, such as a pyridine-diol. The N-atom was released as NH3.
Neither species, however, could utilize other pyridine compounds for
growth. These other compounds included methyl-, amino-, ethyl-, dimethyl-,
and hydroxy-pyridines, and pyridine carboxylic acids. Pathways proposed
for each species are presented in Figures 11 and 12.
Another nitrogen-based compound identified in various coal conversion
effluents is indole. Indole is a benzene-fused, five-membered heterocycle
and its reactivity is determined by the heterocycle portion of the
molecule. The molecule tends to be susceptible to electrophilic attack
at the carbon atoms rather than at the N-atom. This is in contrast to
the pyridines which are relatively resistant to electrophilic attack and
70
-------
OH
Pyridine - 3, 4 - Diol
oo//
00
oo//
t-
HC&J.H
pyruvic acid
formic acid
Figure 9. Pathway proposed by Watson ^t al. (31) for the microbial degradation of 3,4-dihydroxypyridine.
-------
Pyridine-2,5-Diol
H
r* 7
ro
-
eo*//
Mai elc acid
#
o/-/
Figure 10. Pathway proposed by Cain ct_ a.1^. (32) for the microbial degradation of 2,5-dihydroxypyridinc.
-------
Pyridlne
C-tfO
//.o
/
Glutarate
Cofl
Co/9
->
cO
H> CoA
Figure 11. Pathway proposed by Watson and Cain (34) for the degradation of
pyridine by Nocardia sp.
73
-------
Pyridine
Succinate
si/
A///, * //COA
Figure 12. Pathway proposed by Watson and Cain (34) for the
microbial degradation of pyridine by Bacillus sp.
74
-------
subsequent oxidation. Reversion to the simpler aromatic ring occurs
after electrophilic attack, resulting in substitution rather than addition.
The B-position is the more reactive one since reaction at the a-position
would disturb the benzene resonance. The microbial degradation of this
compound seems to occur by hydroxylation of the five-membered ring. A
gram positive coccus which utilizes indole as a sole source of carbon
and nitrogen was isolated from the soil (35) . When grown on indole,
this microoganism could also degrade dihydroxyindole, anthranilic acid
and catechol, indicating that these compounds are intermediates in
metabolism. As in the case of pyridine, the N-atom is released as NH_.
It was also demonstrated that the conversion of dihydroxyindole to
anthranilate and CO- is under the control of an inducible enzyme, termed
dihydroxyindole oxygenase, for this microorganism. The pathway proposed
by Fujioka and Hiroshi (35) is shown in Figure 13.
Biodegradability of anilines, toluidines and other aromatic-amino
compounds depends on ring position and the presence and position of
other substituents (25,36). The data indicate that aniline itself is
readily degradable. Toluidines (methyl anilines) are oxidized as readily
as aniline with the possible exception of o-toluidine. The addition of
a second amino group (amino anilines or phenylenediamines) renders the
compound less susceptible to oxidation. The m-isomer is the least
susceptible. The nitroanilines are markedly resistant to degradation by
both soil bacteria and aniline-acclimated activated sludge. Substitution
of a carboxyl group ortho to the amino group does not increase resistance
to degradation, but m- and p-aminobenzoic acids are relatively resistant,
particularly the m-isomer. The presence of one or two carbon atoms
between the ring and the nitrogen of aniline renders such a compound
relatively resistant to oxidation, but resistance is less with increased
length of carbon chain. Of the primary aliphatic amines, only methyl
amine and n-hexylamine are not oxidized by aniline-acclimiated microorganisms.
Phenol and pyridine were oxidized by aniline-adapted cultures only after
a long period of acclimation.
Other nitrogen compounds that may be of concern are the amides.
Many species of Pseudomonas can utilize acetamide as a carbon and energy
source (37). Some species are also capable of utilizing propionamide
and butyramide as growth substrates (38). Propionamide is utilized as
readily as acetamide, but butyramide utilization is only 2% that of
acetamide. Butyramide may act as an inducer for amidase synthesis. In
some species it is an anti-inducer and will prevent induction by substrate
(acetamide) and non-substrate inducers. In some strains, where amidase
is constituitive, utilization of amides is severely repressed by
butyramide.
Mutant strains of Pseudomonas that can utilize aromatic amides
(phenylacetamide) as a nitrogen source have been isolated (39). Others
have been isolated using phenylacetamide as a sole source of both carbon
and nitrogen. A gram negative rod has been shown to degrade picolinamide
(pyridine-2-carboxamide) to maleic and fumaric acids (33). In all cases,
removal of the amide group appears to take place by means of a simple
hydrolytic cleavage of the carbon-nitrogen bond of the amide group with
the formation of a carboxyl group at that carbon.
75
-------
Indole
Dihydroxy indole
COOfY
ON
t
N)M
Anthram'lic
Acid
Salicylic
Acid
OH
Catechol
Figure 13. Pathway proposed by Fujioka and Hiroshi (35) for the microbial degradation of indole.
-------
Summary—
Again, as in the case of the complex phenolic compounds, little
information is available regarding the behavior of N-containing aromatic
compounds, other than the fact that they are degradable as deduced from
the metabolic pathway studies. The fact that they do not accumulate in
soils suggests that they are degradable in natural environmental systems.
However, the rate of such microbial degradation, and their behavior as
part of a complex mixture at the concentrations found in coal conversion
wastewaters is not known.
Polynuclear Aromatic Hydrocarbons
Microbial Pathway Studies—
Many of the polynuclear aromatic hydrocarbons (PAH's) are known or
suspected carcinogens and, as a result, the oxidation of these aromatic
hydrocarbons by mammalian systems has been extensively investigated.
There is considerably less information, however, on the microbial dissimilation
of these compounds. While a large volume of information is available
concerning pathways and mechanisms utilized by microorganisms in degrading
oxygenated aromatic compounds such as aromatic acids and phenols, the
parent aromatic hydrocarbons have received much less attention. Van der
Linden and Thijsse (16) attribute this to the difficulties encountered
in working with such relatively insoluble substrates, the scarcity of
high purity substrates, and the non-physiological nature of hydrocarbons.
Gibson (40) also suggests that the shortage of studies on parent hydrocarbons
is due to the fact that once oxygen is introduced into the substrate,
the study becomes one of phenol or aromatic acid metabolism. Also,
those enzymes responsible for the incorporation of oxygen into aromatic
hydrocarbons are extremely labile and therefore have resisted detailed
investigation.
Of all the PAH's, only the parent bi- and trinuclear compounds
(naphthalene, anthracene and phenanthrene) have been studied in any
detail. Although it had been reported (41) as early as 1947 that a
broad spectrum of bacteria attack PAH's, it has only been in the last
two decades that metabolic pathways have been determined for the three
above-mentioned parent compounds.
Naphthalene^- A pathway for the degradation of naphthalene by a
species of Pseudomonas was proposed by Davies and Evans (9) and is
presented in Figure 14. It has been demonstrated that the initial
reaction in the bacterial degradation of non-phenolic aromatic hydrocarbons
is the incorporation of two atoms of oxygen into the molecule with the
formation of cis-dihydrodiols (1,42). Once naphthalene has been oxygenated,
subsequent ring fission produces pyruvate and salicylaldehyde. The
latter compound is then degraded to salicylic acid and then to catechol.
Catechol is the final ring-fission substrate and is ultimately degraded
to carbon dioxide and water (see above). The by-product, 1,2-naphthoquinone,
has been isolated but is not considered to be an intermediate metabolite
because it cannot be oxidized by naphthalene-grown cultures. It has
been postulated (16) that 1,2-naphthoquinone is formed from the dihydroxy
compound by a non-enzymatic reaction.
77
-------
*°^H
Naphthalene
1,2 Dihydroxy naphthalene
oo
OH
Sal Icy!aldehyde
•>
o//
'Coo//
Salicylic Acid
oV
ctf
Catechol
Figure 14. Pathway proposed by Davies and Evans (9) for the degradation of naphthalene by a species
of Pseudomonas.
-------
1-, and 2-methylnaphthalene have been shown to be degraded via 3-
and 4-methylsalicylic acids, respectively (43). Degradation then proceeds
by way of 3-, and 4-methylcatechol, respectively.
Phenanthrene and Anthracene-- Soil pseudomonads have been employed
to study the metabolic pathways in the microbial degradation of phenanthrene
and anthracene (44,45,46). The degradation pathway proposed for phenanthrene
is shown in Figure 15. Ragoff and Wender (44) suggest that such a
pathway is in line with the hypothesis of Pullman and Pullman (47) that
polynuclear aromatic hydrocarbons bind to enzymes at the region of
highest electron density (K region). The actual oxidation and ring-
fission reactions take place at nearby bonds of secondary chemical
reactivity. The actual bond that undergoes fission is determined by
electronic and steric configuration of the resulting enzyme-substrate
complex (45). The K region of phenanthrene is the 9-10 bond. Oxidation
then occurs at the 5-6 bond or the 3-4 bond (they are equivalent in
reactivity). Ultimate dissimilation is via salicylic acid and catechol.
Degradation of the linear, condensed polynuclear tri-aromatic hydrocarbon,
anthracene, is similar to that of phenanthrene (45,48) except that the K
region for anthracene is the 1-2 bond, as it is for naphthalene. Attachment
of the enzyme is most likely to occur at this bond. Oxidation and ring-
fission take place on the same ring as enzyme attachment. A proposed
pathway for anthracene degradation is shown in Figure 16.
Ragoff (45) has suggested that there are two types of enzymes
involved in the oxidation of PAH's. One attacks linearly condensed
compounds, such as napththalene and anthracene, and splits the same ring
that is attached to the enzyme. The other enzyme attacks angularly
condensed compounds such as phenanthrene. This enzyme is induced to
split a ring adjacent to the one attached to the enzyme.
Ragoff's work with methylphenanthrenes demonstrates the importance
of substitutent position in the biodegradability of PAH's. Addition of
a methyl group at the 9-carbon of phenanthrene blocked oxidation of the
compound completely. Oxidation of 2-methylphenanthrene was similar to
that of phenanthrene. Oxidation of 3-methylphenanthrene was intermediate
between the two other isomers even though the methyl group was attached
to a carbon involved in ring-fission. It was proposed that 9-methylphenanthrene
was not metabolized due to blockage of the site of enzyme attachment by
the methyl group. The 3-carbon is one of two possible sites of oxidation
and ring-fission. Because only one of the two possible sites is blocked
in 3-methylphenanthrene, oxidation proceeds, but at a lower rate than with
2-methylphenanthrenes.
Other PAH's^- While pathways for the dissimilation of naphthalene,
anthracene and phenanthrene have been proposed, there is relatively
little information on the microbial degradation of other larger PAH's.
It has recently been reported (49) that a number of species of Pseudomonas
are capable of metabolizing fluoranthene and, to a smaller extent,
benzo(a)pyrene in the presence of succinate. Degradation was most rapid
when cultures were in the stationary phase. Degradation was measured by
monitoring the disappearance of the PAH by gas chromatography. All
species capable of degrading fluoranthene could also utilize naphthalene
79
-------
oo
o
1 10
Phenanthrene
1-hydroxy - 2 - naphthandic acid
Salicylic
Acid
o/y
Catechol
Figure 15. Proposed pathway for the microbial degradation of phenanthrene. (After Ragoff and Wender (44).)
-------
9 10
Anthracene
coo//
00
Salicylic
Acid
Cateehol
+ /-/j.0
Figure 16. Proposed pathway for the microbial degradation of anthracene. (After Ragoff (41).)
-------
as a sole source of carbon and energy. Those species which could not
grow on naphthalene did not degrade fluoranthene. Those species metabolizing
the PAH's did so at an average rate of 4 ymoles/hr. The mechanism by
which the PAH was removed from solution seemed to be dependent on the
presence of oxygen and the presence of a heat-labile substance, assumed
to be a protein.
Although there are some reports of such bacteria which appear to
metabolize the larger PAH's, the structures of the resulting metabolites
have not been determined. It can be speculated that degradation proceeds
via hydroxylation mechanisms similar to those reported for smaller
molecules. Gibson et^ ai. (41), have demonstrated the formation of cis-
dihydrodiols from the metabolism of benzo(a)pyrene and benzo(a)anthracene.
The microorganism employed was a strain of Beijerinckia isolated from a
polluted stream and grown on succinate in the presence of biphenyl. The
major dihydrodiol from benzo(a)pyrene was determined to be cis-9,10-
dihydroxy-9,10-dihydrobenzo(a)pyrene. Benzo(a)anthracene was metabolized
to four dihydrodiols, the major isomer being identified as cis-1,2-
dihydroxy-l,2-dihydrobenzo(a)anthracene (see Figure 17).
Subsequent metabolic pathways and the factors regulating these
metabolic processes are not known. Some problems involved with the
study of the larger PAH's are the instability of even sterile solutions,
and the low solubility of the compounds.
Mixed Culture Studies—
All of the above-mentioned metabolic pathway studies were conducted
with pure cultures, under highly-controlled laboratory conditions. When
exposed to various activated sludges, PAH's have been shown to be extremely
resistant to biological oxidation (50). Even the smaller molecules,
naphthalene, anthracene and phenanthrene, showed only very slow rates of
oxidation. Furthermore, none of the sludges showed any significant
ability to acclimate to these compounds. Such results would
imply that removal of PAH's by biological waste treatment would not be
signficant within normal retention times.
Summary of Literature Findings
As described in the preceding section, information concerning the
microbial degradation of the mono- and dihydric-phenols is plentiful.
Less information is available regarding the biodegradability of the more
highly substituted phenols. Of the polycyclic hydroxy compounds, some
information is available on naphthol and biphenol degradation, but
few data have been found concerning the indanols, indenols, and substituted
naphthols. A need also exists for more information on the microbial
degradation of the mono- and polycyclic nitrogen-containing aromatics.
Limited information is available on the parent compounds pyridine,
quinoline, indole, and aniline; biodegradability of the methyl and ethyl
substituted isomers will also have to be examined. Information on the
microbial dissimilation of the polynuclear aromatic hydrocarbons is
mostly limited to naphthalene, anthracene, and phenanthrene. Very
little is known about the degradation of the larger PAH's. In general,
they seem to be quite resistant to biological oxidation, and will require
further study.
82
-------
10
765
Benzo [a] pyrene
cis - 9,10 - Dihydroxy - 9,10 - dihydro
Eenzo [a] pyrene
oo
876
Benzo [a] anthracene
cis - 1,2 - dihydroxy - 1,2 - Dihydro-
benzo [a] anthracene
Figure 17. Formation of cis-dihydrodiols from the microbial metabolism of benzo(a)pyrene and
benzo(a)anthracene. (After Gibson (41).)
-------
EXPERIMENTAL BIODEGRADABILITY STUDIES: PRELIMINARY SCREENING
In order to assess the biological treatability of coal conversion
wastewater and to develop suitable design and operating guidelines, the
following types of preliminary information are required: (a) an assessment
of the biodegradability of the constituent compounds, as reviewed in the
preceding section; (b) biokinetic information describing the rate at
which degradation of the constituents takes place; (c) the concentration
levels at which microbial degradation of the constituents is inhibited
(when the constituent becomes toxic to the microorganisms); and (d) how
the constituents will behave in a composite mixture representative of
coal conversion wastewaters. In view of the paucity of information
available regarding the microbial degradation of many of the constituents
identified in coal conversion wastewaters, an experimental program to
provide such information is under development.
Before performing any extensive biodegradation studies on composite
coal conversion wastewaters or their constituents, it was felt that some
information on the approximate degree of microbial oxidation of each
constituent compound would be valuable. Such a preliminary screening
would provide useful comparative information for each of the constituents,
and could save future time and effort. In order to obtain such preliminary
information, initial screening experiments were conducted to obtain a
gross qualitative assessment of the biodegradability of a number of
specific compounds. This approach was intended to earmark potential
"problem" compounds, i.e., those which are signifcantly resistant to
microbial degradation, those which require a long lag period before
oxidation, or those which show toxic effects (inhibit microbial activity)
even at low concentrations. These data were intended to assist in the
design of more extensive biodegradation studies and to supply some
background information for the development of a synthetic waste and an
acclimated seed culture for these more extensive biodegradation studies
(see Section 7}.
Individual compounds were added to duplicate, acid-washed, 300 ml
BOD bottles at a concentration of approximately 5 mg/1. Dilution water
was prepared from water which had been passed through activated carbon
and ion exchange columns and then glass-distilled. Standard nutrients
were added to the water as was 0.5 mg/1 allylthiourea for control of
nitrification. The dilution water was seeded with 1.5 mg/1 of
domestic sewage obtained from the Chapel Hill sewage treatment plant.
The BOD bottles were filled, stoppered, and incubated in the dark at
65 F for twenty days. Oxygen uptake was measured at various intervals
over the twenty-day period by means of a Weston and Stack dissolved
oxygen meter. This procedure was chosen for its simplicity, and the
ability to incubate cultures over time periods long enough to observe
potential problems with acclimation of the seed to che compound in
question.
Results for the first forty-two compounds tested over the twenty-
day period are presented in Table 24. The monohydric phenols were
judged to be readily degraded, with the exception of 2,6- and 3,5-
xylenol and 2,3,6- and 2,4,6-trimethylphenol. The dihydric phenols,
84
-------
TABLE 24. INITIAL SCREENING OF VARIOUS ORGANIC COMPOUNDS
FOUND IN COAL CONVERSION EFFLUENTS. (ALL
COMPOUNDS WERE TESTED AT 5 mg/1. INITIAL
OXYGEN CONCENTRATION WAS 7.6 mg/1.)
Per Cent 00 Depletion*.
Compound
Phenol
m-Cresol
o-Cresol
p-Cresol
2,5-Xylenol
2,3-Xylenol
2,6-Xylenol
3,4-Xylenol
3,5-Xylenol
2-Ethylphenol
3-Ethylphenol
4-Ethylphenol
2-Isopropylphenol
2,3,5-Trimethylphenol
2,3,6-Trimethylphenol
2,4,6-Trimethylphenol
Catechol
4-Methylcatechol
Resorcinol
4-Hydroxybenzaldehyde
3-Hydroxybenzaldehyde
1-Naphthol
2-Naphthol
6,o'-biphenol
p,p'-biphenol
Naphthalene
1-Methylnaphthalene
2,3-Dimethylnaphthalene
2,6-Dimethylnaphthalene
1,5-Dimethylnaphthalene
Thiophene
3-Methylthiophene
2-Ethylthiophene
3-Ethylthiophene
Pyridine
2-Ethylpyridine
4-Ethylpyridine
Indole
2-Methylindole
3-Methylindole
Indan
Days of
_5
92
92
92
92
4
91
0
79
0
86
85
86
86
56
0
**
87
85
80
3
74
35
86
4
0
92
92
0
0
4
0
1
0
0
0
**
0
60
**
85
4
(continued)
85
Incubation
10
92
92
92
92
6
91
1
80
42
86
85
86
86
75
0
**
87
85
80
3
74
35
86
7
0
92
92
0
0
6
0
1
1
0
75
**
0
60
**
85
4
at 65"F
15
92
92
92
92
86
91
1
80
48
86
85
86
86
79
0
**
87
85
80
27
77
35
86
33
0
92
92
3
0
9
0
1
8
0
75
**
9
60
**
85
15
.2°.
92
92
92
92
86
91
11
84
52
86
85
86
86
80
0
**
87
85
80
50
80
51
86
50
0
92
92
15
3
17
0
4
17
5
75
**
22
* 79
**
85
21
-------
TABLE 24. (continued)
Per Cent ()„ Depletion*
Days of Incubation at 65 F
Compound 5 10 15 20
2-Indanol 5 5 6 12
5-Indanol 5 5 12 22
Quinoline 82 82 82 82
2-Methylquinoline 0 0 79 80
4-Methylquinoline 0000
Gentisic Acid 51 51 52 65
Protocatechuic Acid 58 58 59 65
Succinic Acid 36 36 36 39
Glutaric Acid 49 49 49 68
Dibenzofuran ** ** ** **
*Values of percent 0,, depletion have been corrected for endogenous
respiration of the seed. Approximately 8% of the initial oxygen
concentration had been depleted by the seed in 20 days.
**0xygen depletion was less than that for the seed control alone
indicating that the compound may have inhibited the growth of at
least a portion of the seed population. All compounds having this
designation were retested with phenol added as an alternative carbon
source. In all instances, oxygen depletion increased with addition of
phenol indicating that the primary substrate was not toxic to all
microorganisms at 5 mg/1.
86
-------
resorcinol, catechol, and 4-methylcatechol, were all readily degraded.
The two naphthol isomers showed different oxygen uptakes: 2-naphthol
showed both high total oxygen uptake and high initial uptake, while 1-
naphthol showed only moderate total uptake and low initial uptake. The
lower total uptake may have been due to the lower solubility of 1-
naphthol. The problem and effect of solubility on these initial screening
studies will be addressed and investigated in the later, more extensive
set of experiments.
Biphenol degradation also was dependent on the particular isomer
tested. 0,o'-biphenol showed moderate oxygen uptake while p,p'-biphenol
exhibited a toxic response. Compounds were labeled as toxic when oxygen
uptake for that compound was significantly less than oxygen uptake for
the seed alone. The thiophenes were all relatively resistant to degradation.
Indan and the indanols were only slightly oxidized, and even then only
after a significant lag period. Quinoline was readily oxidized, but its
methyl derivatives were more resistant. 2-Methylquinoline required a
long lag period while 4-methyIquincline was toxic. Ring fission substrates
along with acid degradation products were all readily oxidized.
Table 25 divides the compounds into 3 categories based on oxygen
uptake in 5 days. The compounds are classified as resistant, moderately
degraded, and readily degraded. Those compounds listed as moderately
degraded or resistant will be studied more extensively with regard to
their resistance using an acclimated culture (see Section 7). Those
compounds which were readily degraded will also be studied further to
determine concentrations at which their degradation is inhibited, and to
determine the kinetics of oxygen uptake. The majority of this work will
be done using Warburg respirometric techniques.
87
-------
TABLE 25. SUMMARY OF BIODEGRADATION RESULTS FOR COMPOUNDS AFTER 5 DAYS
Readily Degraded
phenol
m-cresol
o-cresol
p-cresol
2,3-xylenol
3,4-xylenol
2-ethylphenol
3-ethylphenol
4-ethylphenol
2-isopropylphenol
catechol
4-methylcatechol
resorcinol
3-hydroxybenzaldehyde
2-naphthol
3-methylindole
quinoline
gentisic acid
protocatechuic acid
succinic acid
glutaric acid
naphthalene
1-methylnaphthalene
Moderately Degraded
2,3,5-trimethylphenol
4-hydroxybenzaldehyde
1-naphthol
o,o'-biphenol
in dole
Resistant
2,5-xylenol
2,6-xylenol
3,5-xylenol
2,3,6-trimethylphenol
2,4, 6-tr ime thyIpheno1
p,p'-biphenol
dibenzofuran
thiophene
2-ethylthiophene
3-methylthiophene
3- e thy 1 th io phene
2-methylindole
indan
2-indanol
5-indanol
2-me thyIquinoline
4-methylquinoline
pyridine
2-ethylpyridine
4-ethylpyridine
2,3-dimethyInaphthalene
2,6-dimethyInaphthalene
1,5-dimethyInaphthalene
88
-------
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49. Barnsley, E. A. 1975. Bacterial Degradation of Fluoranthrene
and Benzopyrene. Can. J. Microbiol. 21:1004-1008.
50. Malaney, G. W., P. A. Lutin, J. J. Cibulka, and L. H. Hickerson.
1967. Resistance of Carcinogenic Organic Compounds to Oxidation
by Activated Sludge. Journ. Wat. Poll. Con.tr. Fed. 39(12):
2020-2029.
92
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SECTION 7
PRELIMINARY BIOTREATABILITY STUDIES
INTRODUCTION
The preliminary biodegradability screening analysis described in
Section 6 served to identify which of the components of coal conversion
wastewaters were readily biodegradable and which were nondegradable and
would require further study using acclimatized organisms. It should
be noted that in conventional biodegradability studies (using BOD bottles),
very low concentrations (5-10 mg/1) of the test compound are often used.
Although the test compound may be biodegradable under these circumstances,
it could be toxic to microorganisms at the concentration level at which
it is found in the actual wastewater. For example, phenol is known to
be readily biodegradable at concentrations below 100 mg/1, but concentrations
above 1000 mg/1 may inhibit oyxgen uptake, even by acclimatized organisms.
Since coal conversion wastewaters are relatively concentrated with
respect to organic content, toxicity levels for the major constituents
also need to be determined.
OBJECTIVES AND GENERAL APPROACH
This phase of the project has been undertaken in order to:
(a) provide a continuing supply of "seed" organisms for
use in biodegradation studies;
(b) provide reproducible and acclimatized sludges for
respiration studies to evaluate biodegradation and
toxicity of wastewater components under conditions
similar to those which would be encountered in
practice; and
(c) develop preliminary information on biological
treatability of the wastewater.
In order to carry out the appropriate oxygen uptake investigations,
an acclimatized microbial culture must be used. Accordingly, a synthetic
coal conversion wastewater was formulated to provide a mixture of organic
compounds, at known concentrations, for acclimatization and maintenance
of a microbial culture to be used in the subsequent biodegradation and
biotreatability experiments. Ideally, a synthetic mixture should include
all constituents present in coal conversion wastewaters at appropriate
concentrations. From a practical standpoint, however, this is not
possible because all of the constituents are not known, their concentrations
vary depending on the source of the waste, and the mixture would be too
complex to handle experimentally. It was decided, therefore, to formulate
a synthetic coal conversion wastewater that would adequately mirror the
real waste in general composition and concentrations, but would be
simpler and better defined.
93
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COMPOSITION OF SYNTHETIC COAL CONVERSION WASTEWATER
Several criteria were employed in choosing the specific compounds
to be included in the synthetic wastewater, and their concentrations.
Since it was desired to use this waste as a feed for microorganisms,
most of the compounds included are biodegradable. However, not all
constituents in the real wastewaters can be utilized by microbes. Accordingly,
some slowly degraded or nondegradable materials as deduced from the
experiments in Section 6 were included (e.g., 2-indanol, indene, 2-
methyIquinoline, 3,5-xylenol).
In order that the various compounds would be present in concentrations
similar to those encountered in real wastewaters, reference was made to
the summary of constituents found in coal conversion wastewaters (Table
11, Section 4) and the range, midrange, and median concentrations were
determined for each constituent and for each class of compounds (e.g.,
cresols, xylenols, heterocyclic N compounds). From each class, one or
several compounds were chosen to provide a synthetic waste reasonably
representative of real wastes.
Specific chemicals chosen within each class were based on knowledge
of the biodegradability of the compounds, both from the literature
survey and from the preliminary biodegradation screening experiments
(see Section 6). The choice was usually the compound reported at highest
concentration within that class in the real wastes. Often, if a class
contained many components or if differences in biodegradability were
apparent, more than one representative from that class was chosen. The
concentration selected was the midrange value reported for that compound
in the real wastes, or the midrange of the class if only one compound
from that class was picked. If concentration data for a specific compound
were not available, the compound was included in the synthetic waste at
the midrange concentration for its class.
Table 26 lists the composition of the wastewater formulated in the
manner just described. Twenty-eight organic components are included, as
well as inorganic nutrients and pH-buffering additives. The synthetic
waste represents all the major classes of organics present in the real
wastewaters for which data are available, and virtually all of the
compounds that have been shown to be present at high concentrations. A
microbial community acclimatized to this waste should be a useful starting
point for many studies of the biodegradability of specific waste constituents,
mixtures of pure compounds, and eventually complex mixtures of known
chemicals.
PILOT UNITS FOR ACCLIMATION AND BIOTREATABILITY STUDIES
Four 25-liter biological treatment units were constructed, each
consisting of a 7 1/2-in ID lucite tube, fitted at the bottom to a
stainless steel funnel. Compressed air is introduced at the bottom
point of the funnel at rates adequate to insure thorough mixing and
aerobic conditions at all times. Each unit is fed from a reservoir of
synthetic wastewater by a variable-speed peristaltic pump. An exhaust
94
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TABLE 26. COMPOSITION OF SYNTHETIC COAL CONVERSION WASTEWATER
Compound
1. Phenol
2. Resorcinol
3. Catechol
4. Acetic Acid
5. o-Cresol
6. p-Cresol
7. 3,4-Xylenol
8. 2,3-Xylenol
9. Pyridine
10. Benzoic Acid
11. 4-Ethylpyridine
12. 4-Methylcatechol
13. Acetophenone
14. 2-Indanol
15. Indene
16. Indole
17. 5-Methylresorcinol
18. 2-Naphthol
19. 2,3,5-Trimethylphenol
20. 2-Methylquinoline
21. 3,5-Xylenol
22. 3-Ethylphenol
23. Aniline
24. Hexanoic Acid
25. 1-Naphthol
26. Quinoline
27. Naphthalene
28. Anthracene
29. MgSO,=7H?0
30. CaCl^
31. FeNaEDTA
32. NH Cl
33. Phosphate buffer:
KH2P04
Concentration, mg/1
2000
1000
1000
400
400
250
250
250
120
100
100
100
50
50
50
50
50
50
50
40
40
30
20
20
20
10
5
0.2
22.5
27.5
0.34
3820
170
435
668
95
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system vents each unit to the outside of the building.
The reactors are fed continuously, or at one-half hour intervals
through use of a time clock, and are allowed to overflow into separate effluent
reservoirs. The amount of wastewater fed to each reactor is determined
daily by measuring the amount of effluent discharged into each collection
container.
EXPERIMENTAL APPROACH
All four units have been operated as "chemostats," with continuous
and complete mixing, without accumulation of biological solids beyond
levels produced by growth during retention of the wastewater in the
unit, i.e., as CSTR's (continuously-stirred tank reactors) without
recycle of biomass, such that solids retention time equals hydraulic
retention time. One reactor has been operated at a 20-day detention
time principally to produce seed organisms and sludge for use in the
respirometric studies. The remaining three reactors have been operated
at detention periods of 5, 10, and 20 days to develop biodegradation
data on the synthetic waste. The reactors are checked at least once
daily to insure that all systems are operating properly, and mixed
liquor dissolved oxygen and pH are measured. Twice per week the mixed
liquor is sampled to determine suspended solids concentration, as well
as total soluble organic carbon, sludge volume index, and alkalinity.
Initially, the reactors were started using activated sludge from
the Durham, North Carolina municipal wastewater treatment plant, and the
feed of synthetic wastewater was gradually increased over a period of
several days to allow time for acclimatization of the sludge to the
wastewater. Initial studies were performed on full-strength synthetic
wastewater. During the few weeks following startup, however, the units
gradually failed. The five-day chemostat, failed first, followed by the
ten- and twenty-day reactors.
The exact reason for failure is unknown, but several possibilities
have been considered. Uncertain operation at early stages of the investigation
made it possible for the dissolved oxygen occasionally to drop to zero.
Also, the pH decreased to very low levels (approximately 4) and remained
there for extended periods. Further, there is a possibility that some
wastewater constituents could have exerted a toxic effect on the biological
systems as concentrations of these components increased during the
period following startup. The pattern of failure, i.e., in order of ascending
reactor detention period, is consistent with this latter hypothesis.
Because of the possibility of toxic effects, and a desire to stabilize
operations as quickly as possible, it was decided that the waste would
be treated at one-quarter strength during initial investigations. At
some later date, the question of toxicity at higher concentrations could
be explored in more detail. Accordingly, the reactors were started
again, using the same wastewater diluted to one-quarter strength.
The reactors have operated in this fashion without failure, at the
same detention periods as indicated above, since the middle of March of
96
-------
this year (1978). Operating data, as shown in Table 27, suggest that
they are now approaching steady-state. Accordingly, intensive data
collection is underway for this pattern of operation. Filtered samples
of the contents of the chemostats are being analyzed for the following
characteristics:
1. Total organic carbon
2. Biochemical oxygen demand
3. Chemical oxygen demand
4. Organic nitrogen
5. Ammonia nitrogen
6. Nitrite nitrogen
7. Nitrate nitrogen
8. Inorganic phosphorus
9. Total phosphorus
These analyses will be continued at intervals of two days over a period
of two weeks. If the data indicate that steady-state has, in fact, been
attained, intensive sampling will be discontinued and the units will be
modified to operate at another series of appropriate detention times.
At two times during the period of intensive sampling, contents of
the units will be sampled for more detailed analyses to determine specific
effluent constituents. Chemostat contents will be filtered to remove
the microorganisms and other suspended matter and twenty ml aliquots
will be quick-frozen in tightly-capped 50 ml pyrex tubes. These will be
subsequently analyzed for specific organic constituents using gas
chromatography/mass spectrometry and high performance liquid chromatography.
RESPIRATION STUDIES
Equipment has been set up to conduct respiration studies of the
reactor contents, and to evaluate the effects of various wastewater
constituents on biological activity. This will be done by determining
the endogenous respiration rate of mixed liquor from an operating reactor,
and evaluating the effects of additives on the rate of oxygen consumption
in the presence of the reactor contents. An increase in respiration
rate may be interpreted as evidence that the additive is being utilized
by the organisms in their metabolism. On the other hand, decreases in
respiration rate indicate inhibition of biological activity by the
additive in question.
The studies will be conducted by continuously recording the output
of an electrode monitoring dissolved oxygen in a BOD bottle containing
mixed liquor and the additive in question. The additives to be considered
will be components of the synthetic wastewater itself, as well as other
coal conversion wastewater constituents identified in Table 11. This
will allow determination of (1) biodegradability of key wastewater
constituents under conditions similar to those actually present in the
reactors, and (2) acute toxicity effects which may be caused by various
coal conversion wastewater constituents.
The studies will evaluate biochemical effects of the wastewater and
its constituents in the presence of other wastewater constituents normally
97
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TABLE 27. SUMMARY OF REACTOR PERFORMANCE
Reactor #1 5-Day Hydraulic Detention Time
00
Date
3-21-78
4-11-78
5-1-78
5-5-78
5-8-78
5-12-78
5-15-78
5-19-78
5-23-78
5-26-78
5-29-78
5-30-78
£H
7.21
7.31
7.25
7.07
7.16
7.27
7.20
7.20
7.13
7.09
7.06
7.21
MLSS*
(mg/1)
4250
1040
270
213
164
147
115
123
113
111
91
_
MLVSS
(mg/1)
-
270
204
161
147
115
123
113
111
91
_
Effluent
TOC
(mg/1)
30
100
500
360
450
380
415
450
330
405
385
430
TOC +
Removal
-
-
69
78
72
76
74
72
79
75
76
73
TOC
Loading
Factor
-
-
1.185
1.568
1.987
2.17
2.78
2.60
2.83
2.88
3.51
•M
Sludge
Volume
Index
-
-
-
-
-
-
-
-
-
-
-
_
(continued)
-------
TABLE 27. (continued)
Reactor #2 10-Day Hydraulic Detention Time
Date
3-21-78
4-11-78
5-1-78
5-5-78
5-8-78
5-12-78
5-15-78
5-19-78
5-23-78
5-26-78
5-29-78
5-30-78
7.01
4.60
7.32
7.28
7.23
7.37
7.30
7.27
7.20
7.13
7.16
7.22
MLSS*
(ing/I)
4500
1845
985
787
887
846
679
468
531
698
701
_
MLVSS**
(nig /I)
-
-
877
704
680
639
578
468
503
587
622
—
Effluent
TOG
Cng/1)
30
72
110
135
210
255
230
300
205
105
105
95
TOG
Removal"1"
-
-
93
92
87
84
86
81
87
93
93
94
TOG
Loading
Factor"*"1"
-
-
0.182
0.227
0.235
0.250
0.276
0.321
0.318
0.273
0.257
—
Sludge
Volume
Index
—
-
91
76
56
41
59
64
66
50
49
^
(continued)
-------
TABLE 27. (continued)
Reactor #3 20-Day Hydraulic Detention Time
o
o
Date
3-21-78
4-11-78
5-1-78
5-5-78
5-8-78
5-12-78
5-15-78
5-19-78
5-23-78
5-26-78
5-29-78
5-30-78
£l
6.97
5.89
5.67
4.93
5.77
5.87
6.16
6.51
6.59
6.47
6.55
6.62
MLSS*
(mg/1)
4250
1705
1250
1476
1198
1274
1508
1231
1156
1192
1169
_
A*
MLVSS
(mg/1)
-
1250
1183
1114
1153
1162
1060
1135
1031
1054
_
Effluent
TOG
(mg/1)
30
55
50
60
85
60
40
40
45
45
45
47
TOG +
Removal
%
-
-
97
96
95
96
98
98
98
98
98
97
TOG
Load ing t
Factor
-
-
0.064
0.067
0.072
0.069
0.069
0.075
0.070
0.077
0.076
Sludge
Volume
Index
-
-
40
61
71
98
86
81
60
50
51
(continued)
-------
TABLE 27. (continued)
Chemostat - 20-Day Hydraulic Detention Time
Date
3-21-78
4-11-78
5-1-78
5-5-78
5-8-78
5-12-78
5-15-78
5-19-78
5-23-78
5-26-78
5-29-78
5-30-78
£H
6.66
7.
7.
6.
6.
6.
6.
-
6.
6.
6.
7.
09
04
90
91
99
77
95
86
89
10
MLSS* MLVSS**
(mg/1) (mg/1)
3000
1633
1290
1470
1289
975
1210
802
790
953
743
-
-
-
1293
1135
1005
863
961
802
790
825
743
—
Effluent
TOG
(mg/1)
154
106
48
60
130
110
60
50
45
45
50
57
TOG
Removal"1"
%
-
-
97
96
92
93
96
97
98
98
97
96
TOG
Loading
Factfor**
-
-
0.065
0.070
0.080
0.092
0.083
0.099
0.101
0.096
0.109
-
Sludge
Volume
Index
-
-
193
149
124
133
91
93
63
47
47
-
*Mixed liquor
**Mixed
+TOC in
•H-rnr ir
suspended solids
liquor volatile suspended
feed =
laA^no
1600
•Fflr.trm
mg/1
_ Ib TOG in
solids
Feed
Ib MLVSS-DAY
-------
present in the reactors while treatment is underway. This differs
from the Warburg studies described earlier (Section 6), in which
biodegradability and toxicity of constituents are evaluated individually,
without simultaneous presence of the other wastewater components.
FUTURE DIRECTIONS
The effluent from each of the biological reactors will be analyzed
as to specific organic content in order to determine which components
are resistant to biological treatment under the various treatment
conditions. This information will be used to design physical-chemical
treatability experiments involving such processes as adsorption on
activated carbon and chemical oxidation. The physical-chemical
experiments will be conducted on both a component bases (directed at
those specific compounds resistant to biological treatment) and on a
composite basis (directed at the composite effluent from the biological
reactors)-
In addition to specific organic analysis of the reactor effluents,
the biological impacts of the treated effluents will also be analyzed.
Aquatic bioassay, mammalian cytotoxicity, and mutagenicity tests will
be conducted to determine the degree to which any negative biological
impacts associated with these wastewaters can be alleviated by the
various types of treatment.
102
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/7-78-181
2.
3. RECIPIENT'S ACCESSION- NO.
4. TITLE AND SUBTITLE
Assessment of Coal Conversion Wastewaters: Charac-
terization and Preliminary Biotreatability
5. REPORT DATE
September 1978
6. PERFORMING ORGANIZATION CODE
P< c.Singer, F.K. Pfaender, J. Chinchilli,
A. F. Maciorowski, J. C. Lamb HI, and R. Goodman
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
University of North Carolina
Dept. of Environmental Sciences and Engineering
Chapel Hill, North Carolina 27514
10. PROGRAM ELEMENT NO.
EHE623A
11. CONTRACT/GRANT NO.
Grant R804917
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Phase: 11/76-5/78
14. SPONSORING AGENCY CODE
EPA/600/13
^.SUPPLEMENTARY NOTES JERL-RTP project officer T, W. Petrie is no longer with EPA: for
details contact W.J.Rhodes, Mail Drop 61, 919/541-2851.
i6.ABSTRACTTne report gives results of the first phase of a project to assess the environ-
mental impact of coal conversion wastewaters and to evaluate, by bench-scale tests,
alternative treatment methods. Characteristics of coal conversion wastewaters were
obtained from the literature and from information gathered during visits to facilities
for coal conversion process development. For all these wastewaters, about 60-80%
of total organic carbon is phenolic. Remaining organic material includes, nitrogen-
containing aromatics, oxygen- and sulfur-containing heterocyclics, polynuclear aro-
matic hydrocarbons, and simple aliphatic acids. To test treatment methods, espec-
ially biological treatability, on these wastewaters, a synthetic wastewater was formu-
lated which includes 28 organic compounds, inorganic nutrients, and pH buffering
additives. For each class of compounds in real wastewaters, one or more representa-
tives are in the synthetic wastewater at the appropriate mean concentrations. Experi-
ments are underway using the synthetic wastewater at quarter strength in four 25-
liter biological treatment units. These units are to test biodegradability as a function
of retention time and produce acclimated microorganisms for use in respirometric
studies.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Pollution
Coal
Conversion
Waste Water
Assessments
Properties
Phenols
Aromatic Compounds
Nitrogen
Heterocyclic Com-
pounds
Sulfur
Aromatic Polycyclic
Hydrocarbons
Pollution Control
Stationary Sources
Coal Conversion
Biological Treatability
Respirometrics
13B
2 ID
14B
07C
07B
13. DISTRIBUTION STATEMEN1
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
103
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
103
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
RESEARCH TRIANGLE PARK
NORTH CAROLINA 27711
DATE: November 16, 1978
UBJECT: Assessment of Coal Conversion Wastewaters: Characterization and
Preliminary Biotreatabil ity
FROM: N. Dean Smith
Fuel Process Branch (MD-61)
TO: Distribution
Researchers at the University of North Carolina-Chapel Hill are well
into their project to assess the environmental impact of coal conversion
wastewaters and to evaluate, by bench-scale tests, alternative treatment
methods. The attached report describes work during the first 1-1/2 years
of the 5-year project. Characterization of coal conversion wastewaters
and preliminary biotreatability experiments are described.
Based on the characterization of real coal conversion wastewaters, a
synthetic wastewater has been formulated. It includes 28 organic com-
pounds, at concentrations representative of mean values in real waste-
waters. This synthetic wastewater is being used at quarter strength in
25-liter biological treatment units. Biodegradability data, as a function
of retention time, and acclimated microorganisms are being produced.
Attachment
Distribution
Morris Altschuler
Josh Bowen
A. B. Craig
Don Goodwin
R. P. Hangebrauck
T. K. Janes
Steve Jelinek
J. D. Kilgroe
A. Lefohn
G. D. McCutchen
E. L. Plyler
F. T. Princiotta
W. J. Rhodes
N. Dean Smith
D. A. Schaller
R. M. Statnick
P. P. Turner
Ann Alford
Del Barth
T. Belk
David Berg
Kenneth Biesinger
Rudy Boksleitner
J. Bufalini
W. E. Bye
Alden Christiansen
Tom Duke
Al Galli
Stan Hegre
Joellen Huisingh
B. M. Jarrett
J. W. Jordon
R. W. Kuchkuda
A. Levin
L. A. Miller
Don Mount
Gerry Rausa
Walt Sanders
Bill Telliard
Jerry Walsh
111
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