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The composition of residues from municipal refuse incinerators
ENVIRONMENTAL
RESEARCH
7, 294-302
The Composition
( 1974)
of Residues Refuse
Municipal
Incinerators
s. E. HFWDEY,' R. WIRY Public Health Engineering
from
AND R. A. WELLINGS
Section, Imperial
College, London,
United Kingdom
Received December 1, 1972 The organic materials remaining in the residue obtained from municipal refuse incinerators were extracted from the ash, and the aromatic materials were characterized. Two alternative procedures, liquid-liquid extraction and thin layer chromatography, were used in the cleanup procedure following the Soxhlet extraction. The organic materials were then identified by using gas-liquid chromatograph linked to an A.E.I. MS30 mass spectrometer. A detailed analysis of the ash was carried out and particular attention was given to the analysis of such products of incomplete combustion as the aromatic polynuclear hydrocarbons. X-ray fluorescence and stereoscan studies were also used to provide further background information on the residue composition. INTRODUCTION
The increasing trend towards refuse disposal by incineration, and the subsequent possible uses or disposal of the residue, requires that a detailed knowledge of the ash composition be known. Henceforth, in measuring the organic material, it has been common practice to specify the percentage of putrescible material remaining in the ash, which is also used as a measure of the incinerator e5ciency. Although the prime purpose of incineration is volume reduction, it is equally desirable that the residue should not contain sufficient organic materials to give rise to either offensive odours or vermin breeding, or to provide potential for serious ground water pollution. In theory, it might be expected that the majority of organic wastes exposed to incineration would be either volatile or unstable at the temperature involved. There is ample evidence, however, to indicate that small quantities of material are incompletely oxidized and some of these materials remain in the ash residue from the incinerator. In a recent study (Hrudey and Perry, 1972, 1973) the techniques available for assessingthe oxidizable organic materials remaining in the ash obtained from continuous feed direct incinerators have been evaluated. Emphasis was given to an assessmentof the total organic carbon content of the residue, and correlation coefficients relating the various possible methods of analysis were calculated. Of equal importance, however, is the characterization of the individual compounds concerned. Although the oxidizable organic material only constitutes a small percentage of the dry weight of the ash (0.0342% for the majority of continuous feed incinerators) it is necessary to know something about the nature ’ Present address: Environmental Alberta, T5J 2X9, Canada.
Protection
294 Copyright @ 1974 by Academic Press, Inc. All rights of reproduction in any form reserved.
Service, 10025 Jasper Avenue,
Edmonton,
MATERIALS
FROM
INCIN
RESIDUES
295
of the individual compounds, as these could occur in leachate water from the residue tips. Under conditions of incomplete combustion, it would be expected that such unsaturated hydrocarbons as the aromatic polynuclear hydrocarbons would be formed. Several of these materials, although of comparatively high molecular weight, may sublime even at low temperatures. Furthermore, they may also be carcinogenic (Hoffman and Wynder, 1962). Accordingly, it was decided to commence this study by an examination primarily of the aromatic type compounds present in the residue. Following a preliminary Soxhlet extraction into dichloromethane, the aromatic fraction was separated by a further liquid-liquid extraction procedure followed by gas-liquid chromatography. The chromatograph was linked to an A.E.I. MS30 mass spectrometer by a membrane separator and the mass spectrometer was used as a method of characterization and identification of the compounds that were separated. Further background information on the composition of the residue was obtained by X-ray fluorescence analysis and Stereoscan electron microscopy. MATERIALS
1. Purification
AND
METHODS
of Solvents
Solvents were purified by fractional distillation followed by column chromatography using an alumina column. Their purity was checked by gas-liquid chromatography under the conditions of use both on a straight sample, and also on a sample obtained by reducing 50 ml of the solvent down to 50 ~1 using a rotary evaporator under vacuum. 2. Preparation of Sample Residue samples obtained from the incinerator were thoroughly mixed. They were dried at 105°C for 48 hours before crude sorting was performed. Large metallic objects and other materials clearly unsuitable for crushing were removed and the remainder was sieved to separate out all material passing BS mesh 12. The residue was quantitatively crushed to pass BS mesh 72 and then recombined with the initial siftings. Forty grams of this freshly prepared material was extracted overnight with 150 ml of dichloromethane using a Soxhlet apparatus. Two alternative methods were used to separate the aromatic fraction from the extract. (a) Liquid-liquid extraction. The dichloromethane extract was evaporated slowly down to dryness at 0°C using a rotary evaporator. The residue was redissolved in 40 ml of cyclohexane and filtered through a glass fibre filter into a separating funnel. The cyclohexane solution was then shaken with an equal volume of a methanol/water mixture (4:l vol/vol) for two minutes before discarding the lower aqueous layer. A further four, two minute, extractions were carried out with 40 ml of nitromethane and the combined extracts were used for the analysis. (b) Thin layer chromatography. The dichloromethane extract was again concentrated down by rotary-evaporation to 200 PI. This solution was then divided
296
HRUDEY,
PERRY
AND
WFLLINGS
between two silica-gel thin layer plates in a band 8 cm long. Development was allowed to occur in the normal way, using cyclohexane until the solvent front had travelled approximately 15 cm. After drying, the fluorescent bands between rf 0.1 and rf 0.6 were removed for subsequent extraction. Following this extraction, the solution after concentration to 100 ~1 was introduced onto a third silica gel plate and developed with benzene. The aromatic compounds occurring in the fluorescent band rf 0.7-1.0 were then extracted into dichloromethane. 3. Separation of the Aromatic
Hydrocarbons
The extracts from either 2a or 2b were reduced in volume and taken up in 100 ~1 of dichloromethane. The aromatic hydrocarbons were then separated by two alternative procedures. (a) Gas-liquid c.hromutography. Twenty-five microliters of the solution was separated using a Hewlett-Packard 5750 gas chromatograph fitted with dual columns and flame ionization detectors. A 6 ft X % in. stainless steel column packed with 10%UCCW 982 on chromasorb W was used, and the oven run isothermally initially for 6 minutes at 220°C and then temperature programmed at 6”/min up to 270°C where it was held until elution was complete. The helium carrier gas flow rate was 25 ml/min. Calibration of the gas chromatograph for the individual compounds was carried out by spiking further aliquots of the same sample with 3-methyl phenanthrene according to the method described in an earlier paper (Perry, 1971). (b) Further thin luyer chromatography. Fifty microliters of the solution was rotary evaporated to near dryness and taken up in a 100 pl benzene; 25 ~1 of this solution was introduced into a two-dimensional 40% acetylated cellulose thin layer plate which was developed in the first dimension using ethanol :toluene: water ( 17 :4 : 1) , and in the second dimension using ethanol : ether :water ( 4 : 4: 1) . 4. Mass Spectrometry Examination of the individual compounds separated by thin layer chromatography was carried out with an A.E.I. MS9 mass spectrometer using the method described by Majer and Perry ( 1970). Identification and characterization of the compounds separated by gas-liquid chromatography was carried out with the aid of an A.E.I. MS30 double beam mass spectrometer linked to the chromatography by a membrane separator. 5. X-Ray Fluorescence Analysis Semiquantitative analysis of the residues was carried out using a Philips 1220C X-Ray Fluorescence Spectrometer. RESULTS
AND DISCUSSION
There are indications that leachate water from residue tips is contaminated to a much greater degree by soluble inorganic, rather than organic matter (Schoenberger, 1971). This is borne out by the x-ray fluorescence analysis of the residues obtained from three different incinerators (Table 1). It must be noted in studying these results, that the figures are given as weight percent of the element con-
MATERIALS
FROM
INCIN
TABLE
ELEMENTAL AND X-RAY
297
RESIDUES
1
FLUORESCZNCE ANALYSIS Sample
A Wt%
Element H C N Mg Al Si P s Cl K ca Ti Cr MIl Fe Ni
Cl1 Zn Rb Sr Zr Sn Ba Pb
B
0.21-0.24 13.7-18.2 0.51-0.56 0.1-1.0 5-10 10-20 0.1-0.5 0.5-1.0 0.2-1.0 0.5-2.0 5-10 0.1-0.5 0.01-0.05 0.1-0.5 10-20 0.01-0.05 0.1-0.5 0.5-2.0 trace 0.01-O. 10 trace 0.01-0.10 0.01-0.10 0.1-0.6
of dry
C sample
0.17-0.18 22.8-22.9 0.36-0.37 0.1-1.0 5-10 lo-20 0.1-0.5 0.5-1.0 0.2-0.5 0.5-2.0 5-10 0.1-0.5 0.01-0.05 0.1-0.5 10-20 0.01-0.05 0.1-0.5 0.5-1.0 trace 0.01-0.10 trace 0.01-O. 10 0.01-0.10 0.05-0.10
.
0.23-0.32 15.9-16.3 0.48-0.54 0.1-1.0 5-15 10-20 0.1-0.5 0.5-2.0 0.2-0.5 0.5-2.0 5-10 0.1-0.5 0.01-0.05 0.1-0.5 10-20 0.01-0.05 0.1-0.5 1.0-2.0 trace 0.01-0.10 trace 0.01-0.10 0.01-O. 10 0.1-0.6
cerned, rather than as a percentage based on weights of mineral forms actually present. Since the inorganic makeup of the residue is virtually independent of combustion efficiency, this criterion of residue quality is the least amenable to control. Comparatively, the amounts of oxidizable organic materials present in the residues were low. Surface studies of the particulates confirm that there may well be organic materials isolated in pockets within the porous aggregates (Fig. 1). Of the analytical procedures used for the extraction and separation of these materials, the liquid-liquid extraction followed by gas-liquid chromatography proved the most successful. Figures 2 and 3 illustrate the separations obtained by thin layer chromatography, and gas-liquid chromatography, respectively. The main advantage of using the latter technique, lay in the possibility of linking the gas chromatograph via a membrane separator to the MS30 mass spectrometer, With this being a double beam instrument, perfluorokerosene was analysed simultaneously with the compounds eluted from the chromatograph, thus providing a chemical mass marker that facilitated ready characterization of the compounds concerned.
298
FIG. 1.
HRUDEY,
Stereoscan photographs
PERRY
AND
WELLINGS
of ground up incinerator
residues: top, 20 pm; bottom, 4 ,um.
MATERIALS
FROM
INCIN
I
299
RESIDUES
1st. Dimension
-
GQ 1
2
3
N b 0 3 5 B
0
0 5
t
0 6
i +l
,----I
solront -- frgn(,
-------------m-w-
FIG. 2. Two dimensional thin layer chromatogram showing major components. Fluorescent spots under uv: (P) perylene marker (blue-green); (1) purple (A phthalate); (2) bluewhite (benzo-a-pyrene); (3) light yellow (unidentified); (4) light purple (unidentified); ( 5) white ( A phthalate ) ; ( t?) creamy-white ( fhtoranthene ) ; ( 7 ) blue ( phenyl a-napthylamine ) .
0
5
10
15
20 Time
FIG. 3. Table 2.
Gas Chromatogram
of Aromatic
25 (minuterl
30
35
40
45
50
Fraction; the peaks labelled refer to compounds in
300
HRUDEY,
PERRY
AND
TABLE
WELLINGS
2
ANALYSIS OF AROMATIC COMPOUNDS PRESENT IN INCINERATOR ABH Peak number
Wt of compound (rg/kg ash)
Compound
1 2 3 4 5 6 7 8 9 10 11
1.1. Dichloro, 3. Phenyl Propane Phenanthrene + Anthracene Diethyl Terephthalate A Phthalate 3. Methyl Phenanthrene Diethyl Isophthalate Fluoranthene Pyrene A Phthalate Di-isobutyl Phthalate Methyl Chrysene + Methyl Benz-Anthracene Methyl Benz-Phenanthrene Benzfluoranthenes Benzpyrenes + Perylene Triptycene Anthanthrene
12 13 14 15
80.2 12.6 105.2 41.3 2.5 381 47.5 31.3 35.0 1500 45.0
+
180 100 85.0 305
Table 2 lists the compounds separated by gas-liquid chromatography and characterized by mass spectrometry. The retention times of many of these were checked by spiking the samples with pure compounds, and the mass spectrum was used as an absolute method of identification. The remaining peaks were unable to be characterized sufficiently for definite identification, but were found to be mainly aromatic compounds. Fortunately, the polynuclear hydrocarbons have very characteristic massspectra (Majer and Perry, 1970), and this together with the possibility of a good chromatographic separation forms the basis of the analysis obtained. A further advantage of using gas-liquid chromatography was the separation
0 @xl0 0
Tripfycene
253 I
Ill
I 305
I 255
293
205 243
261
231
Fwfluarokerosene
FIG. 4.
Mass
spectrum
181
a9
of triptycene
193
(peak
14).
169
MATERIALS
FROM
INCIN
301
RESIDUES
of the phthaIates from the polynuclear hydrocarbons. The identification of several of these materials in the residues was not altogether surprising, as these types of compounds are incorporated into plastics and alkyd resins. It is not considered that these compounds would present any real difficulties environmentally, as they should be readily degradable. Furthermore, the toxicity of these compounds apparently is quite low (Mayer et al., 1972). Among the other compounds identified in the aromatic fraction (Table 2) was a hydrocarbon of molecular mass 254. This from its highly specific mass spectrum (Fig. 4) and glc retention time is likely to be tryptycene. The concentrations of aromatic polynuclear hydrocarbons present in the residues are not at a sufficiently high level to give concern. They seem to exist at the same level as previously determined in soils ( Gunther and Buzzetti, 1962). Perhaps of more significance, however, is the distribution of these compounds in the residue according to molecular weight (Fig. 5). Although from volatility considerations, one would expect higher levels of the low volatile materials in the residue, it must be remembered that little is known about the mechanism of biodegradation of the higher polynuclear hydrocarbons in soil or in water. Further evaluation of these figures (by method of least-squares minimisation) results in an equation of the form c
=
-1007
+
4.645m
+
7.173m2
X
lo-”
-
5.678m3
X
10e4
+
1.117m4
X
1W6
where C is the concentration of the hydrocarbon and m the molecular weight. Calculations based upon this equation have led to the following values for coronene and ovalene: 4001
300-
-2 j$ 200i .?’ $
loo’-
FIG.
5.
Distribution
moIecularweight.
of
Polynuclear
Aromatic
Hydrocarbons
in ash
residues
according
to
302
HRUDEY,
PERRY
coronene, ovalene,
AND
WELLINGS
464 ccdk;
-4 x lo3 Pg/kg.
Normally, these materials, particularly ovalene, would be difficult to quantitatively analyse in that they become increasingly insoluble in organic solvents the higher their molecular weight. Use of this equation for compounds having molecular weights of the order of 500, demonstrates the importance of considering the complete “class” of compounds rather than one individual member. If the mechanism of biodegradation is in any way related to the mechanism of formation, the presence of much larger quantities of higher molecular weight hydrocarbons could give rise to more significant levels of some of the lower molecular weight carcinogenic materials. The quantities of these materials occurring in the environment, and their methods of biodegradation are forming the basis of a further study being carried out in this laboratory. ACKNOWLEDGMENTS The authors wish to express particular thanks to Messrs. A. E. I. Limited, Manchester, for use of the MS30 mass spectrometer. They are also indebted to Messrs. S. Metcalf, P. L. Bird and P. G. Byrne for helpful discussion and for technical assistance in the x-ray fluorescence work. We also acknowledge the financial support of both the Department of the Environment and the Science Research Council (Grant Number B/SR/8979 to Dr. R. Perry). REFERENCES GUNTHER, F. A., AND BUZZETTI, F. ( 1965). isolation and identification of 0 ccurrence, polynuclear hydrocarbons as residues. Residue Reo. 9, 96-113. HOFFMAN, D., AND WYNDER, E. L. ( 1962). Analytical and biological studies on gasoline engine exhaust. In Analysis of carcinogenic air pollutants. Nat. Cancer Inst. Monograph No. 9, p. 91. HRUDEY, S. E., AND PERRY, R. ( 1972). The Assessment of the Organic Content of Incinerator Residues. Internal report to the Department of the Environment. (Obtainable from Public Health Eng Section, Imperial College, London. ) HRVDEY, S. E., AND PERRY, R. (1973). of the Organic Content of Incinerator A ssessment Residues. Enuir. Sci. TechnoZ. 7, 1146-1147. MAYER, F. L., STALLING, D. L., AND JOHNSON, J. L. ( 1972). Phthallate Esters as Environmental Contaminants. Nature (London), 238, 411-413. and Chromatographic Techniques for MAJER, J., AND PERRY, R. (1970). M ass Spectrometric Determination of Polycyclic Compounds. Pure Appl. Chem. 24, 685-693. MAJER, J., PERRY, R., AND RWDE, M. J, ( 1970). The use of thin layer chromatography and mass spectrometry for the rapid estimation of trace quantities of air pollutants. J. Chromutog. 48, 328-333. PERRY, R. ( 1971). Mass spectrometry in the detection and identification of air pollutants. In “Proceedings. International Symposium on Identification and Measurement of Environmental Pollutants, Ottawa, Canada,” pp. 136-137. SCHOENRERGER. R. J., AND FUNGAROLI: A. A. ( 1971) . Incinerator Residue-Fillsite Investigation. Proc. A.S.C.E. National Water Resources Engineering Meeting, Phoenix, Arizona.
RESEARCH
7, 294-302
The Composition
( 1974)
of Residues Refuse
Municipal
Incinerators
s. E. HFWDEY,' R. WIRY Public Health Engineering
from
AND R. A. WELLINGS
Section, Imperial
College, London,
United Kingdom
Received December 1, 1972 The organic materials remaining in the residue obtained from municipal refuse incinerators were extracted from the ash, and the aromatic materials were characterized. Two alternative procedures, liquid-liquid extraction and thin layer chromatography, were used in the cleanup procedure following the Soxhlet extraction. The organic materials were then identified by using gas-liquid chromatograph linked to an A.E.I. MS30 mass spectrometer. A detailed analysis of the ash was carried out and particular attention was given to the analysis of such products of incomplete combustion as the aromatic polynuclear hydrocarbons. X-ray fluorescence and stereoscan studies were also used to provide further background information on the residue composition. INTRODUCTION
The increasing trend towards refuse disposal by incineration, and the subsequent possible uses or disposal of the residue, requires that a detailed knowledge of the ash composition be known. Henceforth, in measuring the organic material, it has been common practice to specify the percentage of putrescible material remaining in the ash, which is also used as a measure of the incinerator e5ciency. Although the prime purpose of incineration is volume reduction, it is equally desirable that the residue should not contain sufficient organic materials to give rise to either offensive odours or vermin breeding, or to provide potential for serious ground water pollution. In theory, it might be expected that the majority of organic wastes exposed to incineration would be either volatile or unstable at the temperature involved. There is ample evidence, however, to indicate that small quantities of material are incompletely oxidized and some of these materials remain in the ash residue from the incinerator. In a recent study (Hrudey and Perry, 1972, 1973) the techniques available for assessingthe oxidizable organic materials remaining in the ash obtained from continuous feed direct incinerators have been evaluated. Emphasis was given to an assessmentof the total organic carbon content of the residue, and correlation coefficients relating the various possible methods of analysis were calculated. Of equal importance, however, is the characterization of the individual compounds concerned. Although the oxidizable organic material only constitutes a small percentage of the dry weight of the ash (0.0342% for the majority of continuous feed incinerators) it is necessary to know something about the nature ’ Present address: Environmental Alberta, T5J 2X9, Canada.
Protection
294 Copyright @ 1974 by Academic Press, Inc. All rights of reproduction in any form reserved.
Service, 10025 Jasper Avenue,
Edmonton,
MATERIALS
FROM
INCIN
RESIDUES
295
of the individual compounds, as these could occur in leachate water from the residue tips. Under conditions of incomplete combustion, it would be expected that such unsaturated hydrocarbons as the aromatic polynuclear hydrocarbons would be formed. Several of these materials, although of comparatively high molecular weight, may sublime even at low temperatures. Furthermore, they may also be carcinogenic (Hoffman and Wynder, 1962). Accordingly, it was decided to commence this study by an examination primarily of the aromatic type compounds present in the residue. Following a preliminary Soxhlet extraction into dichloromethane, the aromatic fraction was separated by a further liquid-liquid extraction procedure followed by gas-liquid chromatography. The chromatograph was linked to an A.E.I. MS30 mass spectrometer by a membrane separator and the mass spectrometer was used as a method of characterization and identification of the compounds that were separated. Further background information on the composition of the residue was obtained by X-ray fluorescence analysis and Stereoscan electron microscopy. MATERIALS
1. Purification
AND
METHODS
of Solvents
Solvents were purified by fractional distillation followed by column chromatography using an alumina column. Their purity was checked by gas-liquid chromatography under the conditions of use both on a straight sample, and also on a sample obtained by reducing 50 ml of the solvent down to 50 ~1 using a rotary evaporator under vacuum. 2. Preparation of Sample Residue samples obtained from the incinerator were thoroughly mixed. They were dried at 105°C for 48 hours before crude sorting was performed. Large metallic objects and other materials clearly unsuitable for crushing were removed and the remainder was sieved to separate out all material passing BS mesh 12. The residue was quantitatively crushed to pass BS mesh 72 and then recombined with the initial siftings. Forty grams of this freshly prepared material was extracted overnight with 150 ml of dichloromethane using a Soxhlet apparatus. Two alternative methods were used to separate the aromatic fraction from the extract. (a) Liquid-liquid extraction. The dichloromethane extract was evaporated slowly down to dryness at 0°C using a rotary evaporator. The residue was redissolved in 40 ml of cyclohexane and filtered through a glass fibre filter into a separating funnel. The cyclohexane solution was then shaken with an equal volume of a methanol/water mixture (4:l vol/vol) for two minutes before discarding the lower aqueous layer. A further four, two minute, extractions were carried out with 40 ml of nitromethane and the combined extracts were used for the analysis. (b) Thin layer chromatography. The dichloromethane extract was again concentrated down by rotary-evaporation to 200 PI. This solution was then divided
296
HRUDEY,
PERRY
AND
WFLLINGS
between two silica-gel thin layer plates in a band 8 cm long. Development was allowed to occur in the normal way, using cyclohexane until the solvent front had travelled approximately 15 cm. After drying, the fluorescent bands between rf 0.1 and rf 0.6 were removed for subsequent extraction. Following this extraction, the solution after concentration to 100 ~1 was introduced onto a third silica gel plate and developed with benzene. The aromatic compounds occurring in the fluorescent band rf 0.7-1.0 were then extracted into dichloromethane. 3. Separation of the Aromatic
Hydrocarbons
The extracts from either 2a or 2b were reduced in volume and taken up in 100 ~1 of dichloromethane. The aromatic hydrocarbons were then separated by two alternative procedures. (a) Gas-liquid c.hromutography. Twenty-five microliters of the solution was separated using a Hewlett-Packard 5750 gas chromatograph fitted with dual columns and flame ionization detectors. A 6 ft X % in. stainless steel column packed with 10%UCCW 982 on chromasorb W was used, and the oven run isothermally initially for 6 minutes at 220°C and then temperature programmed at 6”/min up to 270°C where it was held until elution was complete. The helium carrier gas flow rate was 25 ml/min. Calibration of the gas chromatograph for the individual compounds was carried out by spiking further aliquots of the same sample with 3-methyl phenanthrene according to the method described in an earlier paper (Perry, 1971). (b) Further thin luyer chromatography. Fifty microliters of the solution was rotary evaporated to near dryness and taken up in a 100 pl benzene; 25 ~1 of this solution was introduced into a two-dimensional 40% acetylated cellulose thin layer plate which was developed in the first dimension using ethanol :toluene: water ( 17 :4 : 1) , and in the second dimension using ethanol : ether :water ( 4 : 4: 1) . 4. Mass Spectrometry Examination of the individual compounds separated by thin layer chromatography was carried out with an A.E.I. MS9 mass spectrometer using the method described by Majer and Perry ( 1970). Identification and characterization of the compounds separated by gas-liquid chromatography was carried out with the aid of an A.E.I. MS30 double beam mass spectrometer linked to the chromatography by a membrane separator. 5. X-Ray Fluorescence Analysis Semiquantitative analysis of the residues was carried out using a Philips 1220C X-Ray Fluorescence Spectrometer. RESULTS
AND DISCUSSION
There are indications that leachate water from residue tips is contaminated to a much greater degree by soluble inorganic, rather than organic matter (Schoenberger, 1971). This is borne out by the x-ray fluorescence analysis of the residues obtained from three different incinerators (Table 1). It must be noted in studying these results, that the figures are given as weight percent of the element con-
MATERIALS
FROM
INCIN
TABLE
ELEMENTAL AND X-RAY
297
RESIDUES
1
FLUORESCZNCE ANALYSIS Sample
A Wt%
Element H C N Mg Al Si P s Cl K ca Ti Cr MIl Fe Ni
Cl1 Zn Rb Sr Zr Sn Ba Pb
B
0.21-0.24 13.7-18.2 0.51-0.56 0.1-1.0 5-10 10-20 0.1-0.5 0.5-1.0 0.2-1.0 0.5-2.0 5-10 0.1-0.5 0.01-0.05 0.1-0.5 10-20 0.01-0.05 0.1-0.5 0.5-2.0 trace 0.01-O. 10 trace 0.01-0.10 0.01-0.10 0.1-0.6
of dry
C sample
0.17-0.18 22.8-22.9 0.36-0.37 0.1-1.0 5-10 lo-20 0.1-0.5 0.5-1.0 0.2-0.5 0.5-2.0 5-10 0.1-0.5 0.01-0.05 0.1-0.5 10-20 0.01-0.05 0.1-0.5 0.5-1.0 trace 0.01-0.10 trace 0.01-O. 10 0.01-0.10 0.05-0.10
.
0.23-0.32 15.9-16.3 0.48-0.54 0.1-1.0 5-15 10-20 0.1-0.5 0.5-2.0 0.2-0.5 0.5-2.0 5-10 0.1-0.5 0.01-0.05 0.1-0.5 10-20 0.01-0.05 0.1-0.5 1.0-2.0 trace 0.01-0.10 trace 0.01-0.10 0.01-O. 10 0.1-0.6
cerned, rather than as a percentage based on weights of mineral forms actually present. Since the inorganic makeup of the residue is virtually independent of combustion efficiency, this criterion of residue quality is the least amenable to control. Comparatively, the amounts of oxidizable organic materials present in the residues were low. Surface studies of the particulates confirm that there may well be organic materials isolated in pockets within the porous aggregates (Fig. 1). Of the analytical procedures used for the extraction and separation of these materials, the liquid-liquid extraction followed by gas-liquid chromatography proved the most successful. Figures 2 and 3 illustrate the separations obtained by thin layer chromatography, and gas-liquid chromatography, respectively. The main advantage of using the latter technique, lay in the possibility of linking the gas chromatograph via a membrane separator to the MS30 mass spectrometer, With this being a double beam instrument, perfluorokerosene was analysed simultaneously with the compounds eluted from the chromatograph, thus providing a chemical mass marker that facilitated ready characterization of the compounds concerned.
298
FIG. 1.
HRUDEY,
Stereoscan photographs
PERRY
AND
WELLINGS
of ground up incinerator
residues: top, 20 pm; bottom, 4 ,um.
MATERIALS
FROM
INCIN
I
299
RESIDUES
1st. Dimension
-
GQ 1
2
3
N b 0 3 5 B
0
0 5
t
0 6
i +l
,----I
solront -- frgn(,
-------------m-w-
FIG. 2. Two dimensional thin layer chromatogram showing major components. Fluorescent spots under uv: (P) perylene marker (blue-green); (1) purple (A phthalate); (2) bluewhite (benzo-a-pyrene); (3) light yellow (unidentified); (4) light purple (unidentified); ( 5) white ( A phthalate ) ; ( t?) creamy-white ( fhtoranthene ) ; ( 7 ) blue ( phenyl a-napthylamine ) .
0
5
10
15
20 Time
FIG. 3. Table 2.
Gas Chromatogram
of Aromatic
25 (minuterl
30
35
40
45
50
Fraction; the peaks labelled refer to compounds in
300
HRUDEY,
PERRY
AND
TABLE
WELLINGS
2
ANALYSIS OF AROMATIC COMPOUNDS PRESENT IN INCINERATOR ABH Peak number
Wt of compound (rg/kg ash)
Compound
1 2 3 4 5 6 7 8 9 10 11
1.1. Dichloro, 3. Phenyl Propane Phenanthrene + Anthracene Diethyl Terephthalate A Phthalate 3. Methyl Phenanthrene Diethyl Isophthalate Fluoranthene Pyrene A Phthalate Di-isobutyl Phthalate Methyl Chrysene + Methyl Benz-Anthracene Methyl Benz-Phenanthrene Benzfluoranthenes Benzpyrenes + Perylene Triptycene Anthanthrene
12 13 14 15
80.2 12.6 105.2 41.3 2.5 381 47.5 31.3 35.0 1500 45.0
+
180 100 85.0 305
Table 2 lists the compounds separated by gas-liquid chromatography and characterized by mass spectrometry. The retention times of many of these were checked by spiking the samples with pure compounds, and the mass spectrum was used as an absolute method of identification. The remaining peaks were unable to be characterized sufficiently for definite identification, but were found to be mainly aromatic compounds. Fortunately, the polynuclear hydrocarbons have very characteristic massspectra (Majer and Perry, 1970), and this together with the possibility of a good chromatographic separation forms the basis of the analysis obtained. A further advantage of using gas-liquid chromatography was the separation
0 @xl0 0
Tripfycene
253 I
Ill
I 305
I 255
293
205 243
261
231
Fwfluarokerosene
FIG. 4.
Mass
spectrum
181
a9
of triptycene
193
(peak
14).
169
MATERIALS
FROM
INCIN
301
RESIDUES
of the phthaIates from the polynuclear hydrocarbons. The identification of several of these materials in the residues was not altogether surprising, as these types of compounds are incorporated into plastics and alkyd resins. It is not considered that these compounds would present any real difficulties environmentally, as they should be readily degradable. Furthermore, the toxicity of these compounds apparently is quite low (Mayer et al., 1972). Among the other compounds identified in the aromatic fraction (Table 2) was a hydrocarbon of molecular mass 254. This from its highly specific mass spectrum (Fig. 4) and glc retention time is likely to be tryptycene. The concentrations of aromatic polynuclear hydrocarbons present in the residues are not at a sufficiently high level to give concern. They seem to exist at the same level as previously determined in soils ( Gunther and Buzzetti, 1962). Perhaps of more significance, however, is the distribution of these compounds in the residue according to molecular weight (Fig. 5). Although from volatility considerations, one would expect higher levels of the low volatile materials in the residue, it must be remembered that little is known about the mechanism of biodegradation of the higher polynuclear hydrocarbons in soil or in water. Further evaluation of these figures (by method of least-squares minimisation) results in an equation of the form c
=
-1007
+
4.645m
+
7.173m2
X
lo-”
-
5.678m3
X
10e4
+
1.117m4
X
1W6
where C is the concentration of the hydrocarbon and m the molecular weight. Calculations based upon this equation have led to the following values for coronene and ovalene: 4001
300-
-2 j$ 200i .?’ $
loo’-
FIG.
5.
Distribution
moIecularweight.
of
Polynuclear
Aromatic
Hydrocarbons
in ash
residues
according
to
302
HRUDEY,
PERRY
coronene, ovalene,
AND
WELLINGS
464 ccdk;
-4 x lo3 Pg/kg.
Normally, these materials, particularly ovalene, would be difficult to quantitatively analyse in that they become increasingly insoluble in organic solvents the higher their molecular weight. Use of this equation for compounds having molecular weights of the order of 500, demonstrates the importance of considering the complete “class” of compounds rather than one individual member. If the mechanism of biodegradation is in any way related to the mechanism of formation, the presence of much larger quantities of higher molecular weight hydrocarbons could give rise to more significant levels of some of the lower molecular weight carcinogenic materials. The quantities of these materials occurring in the environment, and their methods of biodegradation are forming the basis of a further study being carried out in this laboratory. ACKNOWLEDGMENTS The authors wish to express particular thanks to Messrs. A. E. I. Limited, Manchester, for use of the MS30 mass spectrometer. They are also indebted to Messrs. S. Metcalf, P. L. Bird and P. G. Byrne for helpful discussion and for technical assistance in the x-ray fluorescence work. We also acknowledge the financial support of both the Department of the Environment and the Science Research Council (Grant Number B/SR/8979 to Dr. R. Perry). REFERENCES GUNTHER, F. A., AND BUZZETTI, F. ( 1965). isolation and identification of 0 ccurrence, polynuclear hydrocarbons as residues. Residue Reo. 9, 96-113. HOFFMAN, D., AND WYNDER, E. L. ( 1962). Analytical and biological studies on gasoline engine exhaust. In Analysis of carcinogenic air pollutants. Nat. Cancer Inst. Monograph No. 9, p. 91. HRUDEY, S. E., AND PERRY, R. ( 1972). The Assessment of the Organic Content of Incinerator Residues. Internal report to the Department of the Environment. (Obtainable from Public Health Eng Section, Imperial College, London. ) HRVDEY, S. E., AND PERRY, R. (1973). of the Organic Content of Incinerator A ssessment Residues. Enuir. Sci. TechnoZ. 7, 1146-1147. MAYER, F. L., STALLING, D. L., AND JOHNSON, J. L. ( 1972). Phthallate Esters as Environmental Contaminants. Nature (London), 238, 411-413. and Chromatographic Techniques for MAJER, J., AND PERRY, R. (1970). M ass Spectrometric Determination of Polycyclic Compounds. Pure Appl. Chem. 24, 685-693. MAJER, J., PERRY, R., AND RWDE, M. J, ( 1970). The use of thin layer chromatography and mass spectrometry for the rapid estimation of trace quantities of air pollutants. J. Chromutog. 48, 328-333. PERRY, R. ( 1971). Mass spectrometry in the detection and identification of air pollutants. In “Proceedings. International Symposium on Identification and Measurement of Environmental Pollutants, Ottawa, Canada,” pp. 136-137. SCHOENRERGER. R. J., AND FUNGAROLI: A. A. ( 1971) . Incinerator Residue-Fillsite Investigation. Proc. A.S.C.E. National Water Resources Engineering Meeting, Phoenix, Arizona.