RELATIONSHIP BETWEEN WASTE COMPOSITION D ENVIRONMENTAL IMPACT OF WASTE COMBUSTORS By Floyd Hasselriis, P.E., DEE 52 sea songood Road Forest Hills, New York 11375 for publication in WASTE MANAGEMENT AND RESEARCH Draft of July , 1992 ABSTRACT The environmental and health impacts of the stack emissions as well as the collected flyash and bottom ash which result from the operation of municipal solid waste and medical waste combustion systems derive from the chemical composition of the waste , the combustion process , the devices used to control and remove gaseous and particulate emissions , and the degree of dispersion of stack emissions by the atmosphere . Data is presented showing the sources of acids, trace organics and heavy metals in municipal and medical wastes, their split into gaseous and particulate matter and bottom ash as a result of the combustion process , the effectiveness of emission controls and atmospheric dispersion in achieving acceptable environmental concentrations , and factors affecting the composition and solubility of the heavy metals in ash residues . with a complete model of the entire process from waste composition to environmental and health effects , the contributions of the various steps of the process can be evaluated, making possible more effective and economical systems. The effects of waste modification and toxics reduction can be compared with other means of pollution prevention and reduction. Relationship Between Waste Composition and Environmental Impact Floyd Hasselriis Draft of July 9 , 1992 1
Transcript
RELATIONSHIP BETWEEN WASTE COMPOSITION
AND ENVIRONMENTAL IMPACT OF
WASTE COMBUSTORS
By
Floyd Hasselriis , P . E . , DEE
52 seasongood Road Forest Hil l s , New York 11375
for publication in
WASTE MANAGEMENT AND RES EARCH
Draft of July , 1 9 9 2
ABSTRACT
The environmental and hea lth impacts of the stack emi ssions a s wel l as the col l ected flyash and bottom ash which result from the operation of municipal solid waste and medical waste combustion systems derive from the chemical composition of the wa ste , the combustion process , the devices used to control and remove gaseous and particulate emissions , and the degree of di spersion of stack emi ssions by the atmosphere . Data i s presented showing the sources o f acids , trace organics and heavy metal s i n municipal and medi cal wastes , thei r spl i t into gaseous and particulate matter and bottom ash as a result of the combustion proc ess , the effectiveness of emi ssion control s and atmospheric dispersion in achieving acceptabl e environmental concentrations , and factors affecting the composition and solubi l ity of the heavy metal s in ash residues . with a compl ete model of the entire process from waste composition to envi ronmental and health effects , the contributions of the various steps of the process can be evaluated , making possible more effective and economical systems. The effects of wa ste modification and toxics reduction can be compared with other means of pol l ution prevention and reduction.
Relationship Between Waste Composition and Environmental Impact Fl oyd Hasselriis Draft of July 9 , 1 9 9 2 1
I NTRODUCT I ON
The combustion of municipal sol id wastes (MSW ) and medical wastes (MW ) produces emi ssions and ash residues which contain acid gases , trace organic compounds and heavy metal s which can be toxic and harmful to the environment . Source reduction , waste modification and toxics remova l and recycl ing of valuabl e components have a potential for reductions in the quantity of waste which must be either burned or landfi l l ed , as wel l a s reducing the environmental impact o f combustion .
The reduction of harmful impacts requires considerab l e cost and effort . I ncreased efforts to reduce the toxics in the wa ste prior to combustion run into the l aw of dimini shing return s , especia l ly if the emi ssion control s remove almost a l l of the harmful components and/or the environmental effects of the emis sions are not significant .
The most important contributors to harmful emi s sions and their environmental impact can be traced through the process from s ource to environment . The composition of the wastes , the combustion process and the emi ssion control s (if any ) determine the quantities of acid-forming components , organics and heavy metal s emitted by the combustion systems . Computer model ing of stack emi s sions is used to estimate the dispersion of the gases to ground l evel concentrations which are compared with heal th effects . The ash residues , which include the pol lutants whi ch are removed from the emissions , are a l so related to the waste composition and the combustion and control process .
Thi s paper presents data which identifies the sources of acid-forming components and heavy metals in both medical and municipa l waste , and di scus ses how they are affected by the combustion and emi ssion control and dispersion processes . A model relating waste composition to ground l evel concentrations and environmental impact can be used to make practical and costeffective deci sions regarding waste modification , toxics reduction , combustion modification , impl ementation of emi ssion contro l s , and sel ecting site configuration and stack height , as means for reducing ground l evel concentrations safely below thos e establi shed as acceptable .
composition of Municipal and Medical wastes
Municipal waste contains whatever peopl e throw away . Source s eparation or remova l of recyc lables , and provision of s eparate col l ections of household hazardous wastes influence the composition of the waste remaining to be burned . Reduction of toxics in the waste , such as l ead , cadmium and mercury , can a l so be accompl i shed by the manufacturers and by preventing items
Relationship Between Waste Composition and Environmental Impact Floyd Hasselriis Draft of July 9 , 1 9 9 2 2
containing them from entering waste combustors. As an exampl e , battery manufacturers have reduced the mercury content to extremely l ow l eve l s , and use of cadmium in plastics has been reduced and in some cases prohibited by law.
Comparison between medical and municipal wastes
MW from heal th-care facilities contains main ly material s purchased by the hospital o r its food o r other concessions , hence is under the control of the hospital to a large extent. Concern about the high l evel s of hydrogen chloride and potentia l ly toxic heavy metal s (l ead , cadmium and mercury ) in emis sions from combustion of hospital waste has l ed to efforts to reduce the quantity of chlorinated plastics and liquids in hospital wa stes by elimination or substitution. (Green , 1 9 9 2 )
The results of a sorting study of the composition of MW are given in Table 1 , and compared with typical composition of MSW.(Brown , 1 9 8 9 ) The red bag (infectious ) waste was sorted by special procedures which obviated any possible physical contact by the sorters. The c l ear bag waste , a l so typical of heal th care facilities , was general non-infectious waste. In this study both types were roughly equal in quantity. The range shown , which represents a spread of two standard deviations in daily averages , is not very large. I ndividua l bags vary widely , of cours e.
Tabl e 1 COMPOS I TI ON OF RED BAG , CLEAR BAG , AND MUN I C I PAL WASTE (Percent of Total )
*Brown , 1 9 8 9. Range represents +/ - one standard deviation.
Relationship Between Waste Composition and Environmental Impact Fl oyd Has s e l riis Draft of July 9 , 1 9 9 2 3
MSW and MW contain many of the same components : paper , cardboard , plastic fi lm and rigid plastics , rubber and texti l e s , food waste s , and metal cans , bottl e s and plastic container s . MW contains a large amount of di sposable items made of plastic , whereas MSW contains a large quantity of yard waste and mi s c e l l aneous components . The yard waste component of MSW , con s i sting of high-moi sture l eaves and grass and other c lippings , ha s a counterpart in the f luids in MW. They have simi lar amount s of paper , but the MW contained two to three times as much plastic a s municipa l waste .
Analysis of mixed wastes
Municipal solid waste (MSW ) has been extensively analyzed to determine its average overa l l chemical composition . Representative samples of the combustibles are ground and analyzed in a l aboratory . This method a l l ows an accounting o f a l l of the components , and i s useful for determining' the amount of trace organics in the wastes , such as chlorophenol , chlorobenzene , including dioxins and furans , as wel l a s the acids and heavy meta l s . (Hasselriis , 1 9 84; USEPA , 1 9 8 7; NITEP 1 9 85 ) However , this method does not reveal which components of the waste provide the most signi ficant contributions to the emi s sions .
I n order to determine how much each component of the waste , such as paper or plastics , contributes to the overa l l waste c omposition , samples of the various species in the waste are col l ected by sorting and weighing to determine their percentages of the total waste stream . Representative samples of each of the various species are analyzed in the laboratory . The overal l composition of the waste can then be calculated by the methods described below .
Chemical analysis determined from stack anal ysis
A more practical way to estimate the chemical analysi s o f the combustible portion o f the waste is to work back from the quantitie s and types of emissions measured in the stack , prior to the emi ss ion control (if any ) . The amount of hydrochloric acid (HCI ) and sul fur dioxide (S02 ) measured gives a good estimate of the amount of chlorine and sul fur in the waste . Al so , the quantities of heavy metal s such as l ead , cadmium and mercury rel eased from combustion of combustibles can be estimated . (Morri son , 1 9 8 7 ) Some data is avai lable which can be u s ed to estimate the fraction remaining in the ash residues i s unknown .
Relationship Between Waste Composition and Environmental Impact Floyd Hasselriis Draft of July 9 , 1 9 9 2 4
Chemical analysis of the waste components
Conventional ultimate analysis of the individual components o f the wastes obtains the carbon , hydrogen , oxygen , moi sture and content of the waste as wel l as its heating va lue. In addition , analys i s of chlorine , sul fur and nitrogen determine the quantity of acids produced by combustion. Analysis of the ash of the components reveal s the mineral content , especially the heavy metal s emitted after combustion , or disposed of in ash residues. (Hasselrii s , 1 9 8 4; Hasselriis , 1 9 9 1}
Ana lysis of the composite waste can be obtained by analyzing the components and multiplying the individual analyses by the relative quantity of each component in the waste . This method makes it poss ib l e to determine the potential sources of emi s s ion components , but it does not determine whether they exit in f lyash or bottom ash.
split of Metals Between Gas and Ash streams
Mas s ba lances have been attempted , using analyses of the waste , the f lyash and emi ssions , and bottom ash , in order to determine how much of each e l ement in the waste reports to the f l ue gases , and how much to the ash . These balances are costly to perform , and have not achi eved accurate closures since the samples cannot be taken from the same material at the same time . However , it i s c l ear that the acid components can be assumed to report entirely to the gaseous products . Recent data from tests o f MW incinerators shows that substantial dif ferences in vol at i l ity exi st for the heavy metal s of concern . (Durkee , 1 9 9 1}
Tab l e 2 - Percent of Total Metal I nput in Particulate Matter
Metal
Arsenic Cadmium Chromium Lead
S ource : Durkee , 1 9 9 1
uncontrol l ed Particulate Percent of Total Input
2 - 1 0 6 1 - 88
2 - 1 1 3 0 - 6 8
Relationship Between Waste Composition and Environmental I mpact F loyd Hasselriis Dra ft of July 9 , 1 9 9 2 5
Sources of acids in MSW
The main acid-forming elements in MSW and MW are sul fur , chlorine and nitrogen. Ultimate analysis of sorted components o f the waste provides a means of determining the contribution of each component to the acid-forming characteristics of the wa ste. Table 3 , based on studies of MSW at Des Moines , I owa , shows that sul fur , chlorine and nitrogen are present in a l l of the combustibl e components. (GBB , 19 91 ) Multiplying the concentrations in each component by the weight percent of the component in the MSW , obtains the contribution of each component , and the overa l l content in the MSW. The largest contributors of sul fur were the mixed paper , corrugated cardboard yard waste and mi scel lan eous organics (which contain rubber ) . The chlorine came mainly from mixed paper , food and yard waste. Most of the nitrogen came from texti les (acryl ics ) , mixed paper , food and yard waste. The overa l l acid content total ing over 0 . 7% percent of the waste is significant. These data show that yard waste contributed about 10% of the sul fur , 2 0% of the chlorine and 2 0% of the nitrogen.
TABLE 3 - ACID COMPONENTS OF MUNICIPAL WASTE (DES MOINES, IOWA)
Percent (Percent in Com�nent) (Percent of Acid Com�onent) Combustible Component in MSW Sulfur Chlorine Nitrogen Sulfur Chlorine Nitrogen
The main components of MSW (in the united states , especia l ly ) are various types of paper , such as newspaper , corrugated cardboard , office paper and mixed paper consi sting mainly of magazines and junk mail. Table 4 shows that they contain sma l l amounts of l ead , cadmium and mercury. Wood its e l f contains l ead a t up to 2 . 6 parts per mi l lion by weight (ppm ) , and cadmium up to about 0. 4 ppm , and sometimes measurabl e amounts of
Relationship Between Waste Composition and Environmenta l Impact F loyd Hasselriis Dra ft of July 9 , 19 9 2 6
mercury. The l ead and cadmium in newspaper varies with the amount and kind of printing. The slick advertising stock samples showed up to 0.7 9 ppm of l ead and up to 0.3 ppm of mercury. Bond paper and magazine paper contained more l ead , and recyc l ed paper had up to 2.5 ppm of l ead.
The metal s content of municipal waste , compost , and medical waste , shown in Tabl e 5 , are much higher than those seen in wood and paper products. MSW ranged from 3 3 to 6 0 ppm of l ead , whereas back calculations from stack emissions show that MW combustibles contained 12 to 2 3 ppm. Cadmium in MSW and MW was quite similar.
The l ead content of compost made from trees and shrubs tested in Europe was found to be ten times as high as in wood and paper , and similar to MSW , possibly due to the continued use of l ead in gasoline. The compost made from MSW contained 5 6 0 ppm o f l ead , 2 0 0 times that of paper , and 3.8 ppm of cadmium. Refusederived fuel was found to average 1 6 0 ppm of l ead , 1.6 ppm of cadmium and a lmost 1 ppm of mercury.
Metals content of combustible components of municipal waste
Detail ed analysis of the critica l metal s in the various combustible components of MSW have been carried out in order to identify and quantify their sources. Table 6 shows an ana lysis of data obtained from analysis of MSW from Winnebago , Wisconsin in 1 9 9 0.(GBB , 19 91) This sorting study focus s ed on recyclable materia l s , and disposabl e diapers since they had become an is sue. Non-combustibles such as ferrous meta l , aluminum , glass and misc e l l aneous inorganics are not listed.
The metal concentrations found in each component are mul tiplied by the percent of that component in the MSW to obtain the contribution to the total metal content. The percent contribution to the total is then calculated by dividing by the tota l content of each metal.
The results of this study show that 4 7% of the cadmium was contributed by the " other " (non-recyc lable) plastics and textil e s , 19% was found in the recyc lable PET (milk) bott l e s , about 2 0% came from the various paper products , and " other organic s " supplied 1 3%. On the basis of this data it would appear that considerabl e potential exists for reducing the cadmium in the waste by substitution of other additives , fil l ers and colors in plastics , especia l ly in rigid plastics.
Relationship Between Waste Composition and Environmental I mpact F loyd Has s e l riis Draft of July 9 , 19 9 2 7
Tab l e 4 - LEAD, CADMIUM AND MERCURY I N PAPER PRODUCTS (Parts per mi l l ion of waste)
B leached 1. 7 9 0 . 21 Paper - upper range 2 . 5 6 0 . 41 0 . 13 Paper - l ower range 0 . 3 2 0 . 10 0 . 0 2
Newspaper Unprinted 0 . 3 2 0 . 13 Comics 0 . 3 7 0 . 0 7 C l a s s i fi ed section 0 . 4 8 S l ick advertising 0 . 7 2 0.10 S l ick advertising 0 . 7 9 0.3 0 Bond paper 0 . 5 0 0 . 0 5
Junk mai l - glossy 0.6 0 . 0 4 Junk mai l - glossy 0.9 2 0 . 0 3
Magazine - glossy 0 . 9 0 0 . 0 5 S l ick advertizing 1 . 3 0
Commercial recyc l ed 0 . 7 6 0 . 4 0 . 11 Commercial recycl ed 2 . 5 6 Residential recycl ed 2 . 2 Residential recyc l ed 2 . 5 0.1 0.05
Relationship Between waste Composition and Environmenta l Impact F loyd Hasselriis Dra ft of July 9, 19 9 2 8
Table 5 LEAD, CADMIUM AND MERCURY IN WASTES (Parts per million of waste)
COMPONENT
Municipal waste
Prince Edward I sl anda Portland, OR, Residentialb
Portland, OR, Cornrnercialb
Des Moines, lAb
Swedish dataC
Average :
Compost - tree and shrubc Compost - Gardenc compost - paperc
MSW Compost (1 3 plants) C
RDF - 1 5 plant averageC
U.S. Bureau of Mines MS�
Medical waste incineratorse (calculated from emis sions)
sutter Genera l Stan ford Kaiser-Permanente s t . Agne s Cedars Sinai
a . N ITEP, 1 9 8 5 b. GBB, 1 9 9 0, 1 9 9 1 c. Bergval l, 1 9 8 5 d. Hassel riis, 1 9 84 e. Morrison, 1 9 8 7
Average :
LEAD
6 0 2 4 5 0 3 3
3 7
4 4
2 3 5 7 5 3
5 6 0
1 6 0
3 3 0
1 1. 8 2 3.1 2 1.4 2 1.7 2 1 .7
1 9.9
CADMIUM
3.0 1.0 1.2 0.5
1.1
1.5
<1 0.9 2.8
3.8
1.6
9.0
0.9 0.8 1.4 1.6 2.2
1.4
MERCURY
3.0
0.9 .5
1.8
<1 <1
0.1
2.9
0.9
Relationship Between Waste Composition and Environmental Impact F loyd Has s e l riis Draft of July 9, 1 9 9 2 9
Most of the chromium (5 8%) was found in the paper products , and 2 3% in the other (usual ly rigid) plastics . About 3 7% o f the l ead was in paper products , 2 7% in other plastics , and 2 1% in the other organic s . Mercury was found in some samples of polystyrene and , surprisingly , in some diaper samples . About 3 0% of the nickel was in paper products , 2 7% in other plastics , and 5.6% in textil es , perhaps in pigments .
Once it is determined that certain components of the waste are the major sources of acids or heavy meta l s , attention may be given to determining why thes e components are present , and whether or not they might be removed or replaced by substitution of more benign materia l s .
Metals used in manufacture of plastics
The higher content of metal s in MSW and MW as compared with paper may be attributed to a large extent to plastics , which are made with l arge amounts of stabilizers , fil l er materia l s and co lorants . Tables 7 to 9 list the main colorants and stabilizers (fi l l ers) used in plastics . Reductions in emissions o f metal s can be achieved by reduction , elimination o r substitution o f metal s o f c ritical concern .
Metals found in Medical wastes
Detai l ed sorting analysis of Medica l wastes carried out by the Minnesota Pol lution Control Agency found correlations between uncontrol l ed metal s emissions and components of the waste . (Torkel son , 1 9 9 1)
Arsenic was found in operating/delivery room waste , and in c l oth , blue plastic/rubber , and sterilization wrap (used for autoc laving) . Copper behaved similarly to arsenic , a l so found in blue combustibles . Reducing blue combustibl e items would reduce arsenic and copper emiss ions .
Copper emis sions correlated with metal lic copper in e l ectrical items , as wel l as to latex gloves and PVC . Lead and copper correlated , and l ead was found in PVC and many items and materia l s . Manganese correlated with aluminum and nonchlorinated plastic . Cadmium correlated with red plastic s .
Sources of Chlorine in Medical wastes
Polyvinyl chl oride (PVC) , having about 4 5 percent chlorine content , may contribute a large fraction of the HCl emissions , but other components , such as paper and food , a l so contribute similar l arge amounts . Hospital wa stes include chlorinated solvents and disinfectants . The proportion of various types o f
Relationship Between waste Composition and Environmental Impact F l oyd Has s e l riis Draft of July 9 , 19 9 2 1 0
plastics in medical wastes shown in Tabl e 9 was reported in a study o f both red bag (infectious) and c l ear bag (non-infectious) waste s . (Brown, 1 9 8 9 ) Note that thi s red bag waste contained 3 0 percent plastics, and 15% o f that i s PVC, with 45% chlorin e : the result i s that 2 0 0 0 pounds of this waste contains 2% chlorine, 4 0 pounds o f chlorine per ton, or 2 0, 0 0 0 parts per mi l l ion by weight . Thi s would produce emi ssions of about 13 0 0 parts per mi l l ion (by volume) of ReI in the uncontrol l ed stack gases, and would require 9 6% control to reduce the emissions to 5 0 ppm .
AFFECTS OF THE COMBUSTION PROCESS
The combustion process does not destroy the e l ements in the waste; however, it affects the chemical form of combustible and inorgani c compounds, determines how much of each e l ement escapes with the combustion products, the partic l e size of the so l id emi s sions in the gases, and the physical and chemical nature of the e l ements and compounds in the col l ected flyash and bottom ash . Extensive tests such as those which Environment Canada has carried out on a modular (starved-air) system and a mas s -burn waterwa l l system, achieved fairly good mas s -balances on organi c s and inorganic components of MSW . (NI TEP, 19 85; NITEP, 19 8 8)
Al l o f the acid-forming chlorine, sul fur and nitrogen are expected to exit in the combustion gases . The heavy meta l s report t o either the f lyash o r bottom ash, a s noted in Table 2, above . The concentration of meta l s on the f lyash i s related to both the amount of f lyash l i fted and the temperature of the f l ame .
Fl yash l ifted from the combustion zone
The amount of f lyash (particulate matter) rising from the combustion process is dependent on factors such as the f l ame temperature, vertical velocities, distribution of underfire and overfire air, and their ratios, and the nature of turbu l ence which takes place, hence upon the technology and methods of operation . The amount of particulate matter l i fted and the organic and metal s content of this particulate is highly sensitive to the combustion conditions, therefore .
Relationship Between waste Composition and Environmental I mpact F loyd Hasselriis Draft of July 9, 19 9 2 11
TABLE 6 - METALS IN COMBUSTIBLE COMPONENTS - WINNEBAGO, WIS CONS I N (Parts per Million in Component)
Percent COMPONENT in MSW Cadmium Chromium Lead Mercury Nickel
Newsprint 5.7 0.01 0.05 0.03 0
Office Paper 10.0 0.63 194 50 0.00 595
Magazines 10.0 0.64 130 50 0.00 183
Mixed Paper 10.0 0.83 123 46 0.00 388
Plastic Containers 0.2 3.32 530 269 0.00 1685
Other Plastics 6.0 11.67 344 231 0.00 1249
EPS 0.1 0.82 168 46 0.17 1404
PET 0.5 60.70 132 442 0.00 349
HOPE 0.5 0.56 103 445 0.00 355
Other Organics 7.3 2.88 171 148 0.00 517
Texti les 4.5 1.05 15 32 0.00 347
Diapers 1.1 1.15 93 61 0.05 222
Laminated Paper 8.1 1.20 75 53 0.00 232
(Metals in Components, mg/kg MSW) Percent
COMPONENT in MSW Cadmium Chromium Lead Mercury Nickel
F luid 1 3 . 1 Glass 1 1 . 6 Aluminum 0 . 5 Steel 0 . 3 s tainl es s Steel 0 . 1 Copper 0 . 1 Other Metal s 0 . 1 Other 1 . 5
Source : Torkel son, 1 9 9 1
The distribution o f primary air supplied through the grate and secondary air supplied above the grate in the combustion chamber inf luences the amount of particulate l i fted, and hence the concentration of volati l e metal s found in the flya sh. Figure 1 is ba sed on data obtained from tests of the Quebec waterwal l incinerator under a wide range o f operating conditions. The concentration of cadmium in the col lected particulate matter fel l a s the rate o f discharge of f lyash increased. At 7 0% o f the design f iring rate of 2 8 tonnes per hour 4 6 kg/hr of f lyash was c o l l ected; design fi ring produced 4 7 to 7 0 kg/hr under good operating conditions, and high fire ( 1 5% over design) and poor
Relationship Between Waste Composition and Environmenta l Impact F loyd Hasselriis Draft of July 9 , 1 9 9 2 1 5
operation at design firing rates produced about 1 3 0 kg/hr. The cadmium concentration in the flyash ranged from about 0.0 2% at low fire down to 0.0 0 6% at high fire. The mass rate of cadmium emissions ranged from 5 g/hr to 1 0 g/hr over the range of firing rates. Similar tendencies were noted for the lead in the flyash , a s seen in Figure 2 , which ranged from about 0.3 to 0.6% of the flyash at rates of 3 5 0 down to 1 5 0 g/hr.
Figure 1 - Concentration of cadmium versus flyash discharge rate.
Figure 2 - Concentration of lead versus flyash discharge rate.
The amount o f flyash lifted depends upon the quantity and distribution of combustion air supplied to the combustion chamber. Starved-air incinerators (typically used for MW combustion) supply only about 5 0% of air theoretically required for combustion in the primary chamber , hence produce far less particulate matter (flyash) than excess-air incinerators typically used for MSW combustion , which may provide 2 0 0% of theoretical air in the combustion zone.
Typical particulate mass emis sion factors vary widely for dif f erent combustion technologies , as illustrated in Table 1 2.
Table 1 2 - Particulate Emission Factors for Various Technologies
Particulate Mass Emis sion Type of Combustion Technology Factor, pounds per ton MSW
The temperature at which combustion takes place substantially influences the particle size distribution of the collected flyash. Figure 3 shows the influence of the secondary furnace temperature on the particle size distribution of flyash emitted by a two-chamber starved-air incinerator. As the furnace temperature was changed from 1 3 5 0°F (7 3 2°C) to 2 1 5 0°F (1 1 7 6°C) , the 5 0% particle size changed from 0.7 to 3 microns. I n other terms , the percentage of particles less than 1 micron changed from 1 5% to 6 2%. Analysis of the particulate matter showed that sodium chloride (salt) wa s the major component of the sub-micron
Relation ship Between waste Composition and Environmental I mpact Floyd Has s elriis Draft of July 9 , 1 9 9 2 16
particulate , and the most influenced by the furnace temperature. The generation of salt fume presents a probl em for wet scrubbers , which are not a s e f fective in removing this component as fabric filters. (Brady , 1 9 9 1)
Figure 3 - Partic l e size distribution vs. combustion temperature.
Dioxin and furan emissions versus particulate quantity
combustion conditions and high rates of particulate generation have been found to correlate with increased emissions of dioxins and furans and their precursors , chlorophenol s and chlorobenzenes. Figure 4 , based on the Quebec measurements at the outl et of the el ectrostatic precipitator (ESP) , shows a roughly 2 0 -time increase in total PCDD (polychlorinated dibenzo-p dioxin) emissions from " good , design rate " emissions of 5 0 ng/M3
to about 1 5 0 0 ng/m3 under conditions of " poor combustion , l ow temperature s " and "poor air supply" or distribution. Total PCDF (polychlorinated furan) emis sions showed roughly a ten-time increase under poor conditions. Under good conditions , both PCDD and PCDF showed a linear increase in the emis sion factor (�g/tonne) with the rate of flyash discharge. (NI TEP , 1 9 8 8; Has s e l riis , 1 9 9 0)
Figure 4 - Effect of f lyash rate on PCDD and PCDF emis sions.
ABSORB I NG , CONDENS ING AND COLLECTION OF PARTI CULATE
Methods for control ling particulate and acid gas emissions include absorption , condensation , and c o l l ection of particulate by e l ectrostatic precipitators or baghouses. Acid gases can be absorbed a l ong with solid particulate into water dropl ets in wet scrubbers , and f lushed away. I n spray-dryer absorbers , the drops are dried to powder which can be col l ected by the bag fil ter. (Getz , 1 9 9 2)
Effect of temperature on control of emissions
The temperature to which the combustion products are coo l ed before they enter the stack has an influence on the emissions of acid ga ses , volatil e heavy metals and trace organics. Sul fur dioxide and hydrogen chloride are most effectively condensed and removed a s the gases approach the acid dewpoints , roughly around 2 3 5°F (1 1 4°C) . Emissions of mercury were found to be reduc ed f rom about 7 0 0 mg/m3 at 5 0 0°F to 1 5 mg/m3 at 2 5 0°F when a s crubber/baghouse was used at Quebec City. However , it was later found that these high removal ef ficiencies were the result o f the poor combustion and high carbon content of the flyash during
Relationship Between waste Composition and Environmental Impact F loyd Ha ssel riis Draft of July 9 , 1 9 9 2 1 7
those tests . When good combustion minimizes carbon in the f lyash , it has been found that adding carbon can produce high mercury removal efficiencies . (Byrna , 1 9 9 1 ; Durkee , 1 9 9 2 ; Getz , 1 9 9 2)
Wet scrubbers , especially suited to sma l l medical waste incinerators , operate at around IS0°F , hence are especial ly e f f ective in contro l l i ng acids , organics and metal s by condensation . Although fabric filters cannot be operated too c lose to the dewpoint to avoid cementation of the f lyash on the bags , hence are l imited to the range of about 2 7SoF (13S0C) to 3S0°F (17S0C) , are sti l l quite ef fective .
Effect of APC Temperature on Dioxin and Furan Emissions
Dioxin s and furans which are found in particulate deposits retained at the back end of boi l ers , in ESPs , and on fabric f i lters for suf f icient time , increase at temperatures above IS0°C , due to various mechani sms , including the chemical reactions with FeCl3 in the presence of Hel and oxygen . PCDD and PCDF in vapor form may condense on particulate and be col l ected . The degree of chlorination shi fts for complex reasons , often c reating more toxic congeners . (Vogg , 1 9 8 7; Hagenmaier , 19 8 7)
Extensive research has been carried out to ascertain the factors i n f luencing organic and inorganic emissions . Researchers have found that PCDD and PCDF emi ssions are the result of organi c precursors which survive the combustion process . As noted above , optimum air distribution , excess oxygen and combustion conditions have been found to minimize these precursors . There i s evidence that l ime injection in the furnace and carbon injection prior to a baghouse are effective in reducing dioxin and furan emi ssions . (Gu l l ett , 19 8 9 )
Figure S shows data from di fferent sources which demonstrate the l ogarithmic increase in PCDD and PCDF with temperature . The increases found in l aboratory flyash (nanograms per gram of f lyash) by Vogg et a l are simi lar to those found from tests o f a wide range of ful l -scale waste combustors . The MSW combustor having a quench tower followed by an e l ectrostatic precipitator (Q/ESP) wa s found to produce IS to SO times higher emi s sions at SSO°F(2 8 8°C) than at 4 0 0°F (2 0 4°C) ; data from thi s plant c l early showed that PCDD and PCDF were produced in the precipitator at these temperatures . (Ki lgroe , 1 9 9 2) The medical waste incinerators tested for the Cal i fornia Air Resources Board (CARB) showed a Iso-time di f ference from 6 0 n�/m3 after a wet scrubber operating at 1 6S0F(7 4°C) to 9 , 0 0 0 ng/m from a baghouse operating at 4S0°F ( 2 3 2°C) . (CARB , 1 9 9 0)
Figure S - PCDD and PCDF emi ssions versus gas temperature .
Relationship Between Waste Composition and Environmental Impact F loyd Hasselriis Draft of July 9 , 19 9 2 1 8
FLYASH , S CRUBBER RES I DUES AND BOTTOM ASH
Due to the vol atility of cadmium and l ead at combustion temperatures , flyash can be expected to contain relatively high concentrations of these metal s on their surfaces due to condensation as the particles are cool ed. Furthermore , due to the presence of HCl in the combustion gases , chlorides of these metal s wi l l form. Since these are the most soluble forms of l ead and cadmium , they are a source of concern if reactions do not take place to reduce the solubi l ity of these metal s. The f lyash and scrubber residues must be treated or disposed of in such a way that these soluble metal salts do not contaminate the environment and drinking water. (Hasselriis , 1 9 8 9 )
When a wet scrubber is used , the soluble metal salts formed when removing acids are absorbed by the scrubbing water. The blowdown from sma l l scrubbers often may be discharged into the muni cipal water s ewer without causing excedence of disposal standards. Larger facilities may have to treat thi s blowdown or eliminate it by evaporation in some way.
When l ime injection systems empl oying baghouses are used to capture acids and particulate , the dry powder f lyash and scrubber residues which are produced create unique probl ems of handling and disposal , since they can cause 'fugitive dust' and contain the most soluble forms of the toxic heavy metal s. Lead and cadmium chlorides are not soluble to a large extent when the pH is above about 7, but l ead becomes more soluble when the pH increases above about 1 1 or 1 2. Excess l ime in the scrubber residues can drive the pH up into this range. It is therefore important to manage these salts careful ly or convert them to other chemical forms , such as carbonates; or bind or encapsulate them , such as ln a pozzolanic matrix.
Figure 6 - Soluble l ead in MW incinerator l eachates
Figure 6 reveal s some important findings about the ash residues from a MW incinerator , i l lustrating the variabi l i ty o f the l eaching characteristics of individual samples , and the critical nature of the l ead contained in the ash , resulting from its degree of solubi l ity. When the dry ash remaining after overnight burndown i s subjected to the USEPA Toxic Characteristic Leaching Procedure (TCLP ) , hal f of the samples exceeded the EPA l imit o f 5 ppm o f l ead in the l eachate. When the ash was pas s ed through the quench tank , the samples exhibited much l ower l ead concentrations , 5 0% l e s s than 0.2 ppm , but about 1 5% of the s amples exceeded the EPA limit. The water in the quench tank was found to have similar but l ower concentrations of l ead. (Unpubl i shed data )
Relationship Between Waste Composition and Environmental Impact F loyd Has s e l riis Draft of July 9 , 1 9 9 2 1 9
STACK CONCENTRATIONS
Emis sion contro l s using a l ka line reagents and temperature reduction are extremely ef fective in control ling acids , organic s and meta l s , as noted above . Typical ly , 9 9% reduction of HCI , or emissions l ess than 50 ppm can be achieved; carbon monoxide can be reduced to 5 0 ppm or less , and trace organics (dioxins and furans) can be control l ed to 7 0% to 9 5% . Metal s are control l ed by better than 9 9% in the case of municipal incinerators , and a l so medica l waste incinerators .
stack emis sions reported based on recent tests of MW incinerator s are shown in Table 1 3 . Typical emis sions are listed for the three most common emis sion control systems now used in the us : dry-injection/fabric filter , venturi wet scrubber , and spray-dry/ fabric filter systems . Particulate matter is reduced to 0 . 1 5 mg/m3 by fabric filters . wet scrubbers have genera l ly been abl e to reduce PM to 0 . 0 4 5 grains per standard cubic foot (gr/dsc f) (2 . 0 mg/m3) , but require a means for capturing the submicron salt mist in order to meet 0 . 0 1 5 gr/dscf (0 . 7mg/m3) . Al l three appear to control the absolute emis sions of HCI and heavy metal s roughly equa l ly wel l , provided that suf ficient reagent is used .
The e f ficiency of control exhibited by these control systems is listed in Table 1 3 . I t should be noted that absolute emissions are more consistent than ef ficiencies , since e f ficiencies are based on what are often highly variabl e in l et concentrations .
TabLe 12 - Comparison of Emissions from Various APC Systems
ParticuLate Matter (gr/ds3f)
(mg/M )
Dry Injection Fabric FiLtera
0.003 0.138
PCDD+PCDF (ng/nM3) 6-132
Meta Ls (/lg/M3) Arsenic Lead Mercury Cadmium Chromium
a. Durkee, 1992 b. Sanders, 1991 c. BL izard, 1992
0.7-1 4-7
390 2-10
10-204
Venturi b Scrubber
0_019 0_86
4
0.06 12 5 1.7 0.1
Venturi Scrubbera
0.046 2.1
398
9 1745 300 217 25
Spray Dry Fabric FiLterC
0.0038 0.175
1.1 4
436 1.3 4.2
Relationship Between Waste Composition and Environmental Impact F loyd Has s e l riis Draft of July 9 , 1 9 9 2 2 0
TabLe 13 - Comparison of Efficiencies of Various APC Systems
Dry Injection Venturi Fabric FiLtera Scrubbera
ParticuLate Matter 96-97.3 99.19
PCDD+PCDF 68.3-94.5* 83
MetaLs Arsenic 82-86 91.7
Lead 99.7 99.8
Mercury 0-95* 23.6-89*
Cadmium 99.5 99.6
Chromium 60-70 98.5
* High efficiencies due to carbon addition. a. Durkee, 1992
b. BLizard, 1992
Spray Dry Fabric FiLterb
99
30-98.6*
>92.7
99.9
29-90*
99.8
98.3
RELATING EMISSIONS TO GROUND LEVEL CONCENTRATIONS
Regardless of the absolute values of the concentrations of pol lutants in the stack emis sions after the emi ssion control s, their s igni f i cance depends upon how much they become di luted before they reach 'sensitive receptors.' The term " di lution factor " is defined here as the ratio of the concentration measured in the stack divided by the concentration at the most a f f ected point at ground l evel, as determined by computer model ing .
I n the process of dispersion, high di lution factors can be achieved . They may range from as l ow as 5 0 0 for sma l l fac il ities with l ow stacks and receivers located in adjacent bui ldings to up to 2 5 0 , 0 0 0 for faci l ities with higher stacks and favorabl e di spersion . (Hasselri i s , 19 9 2) Figure 7 shows the di lution factors which were determined by computer model ing data obtained for a wide range of waste combustion systems by CARB . Thi s graph shows that the degree o f pol lutant di lution achieved by sma l l medical waste o r commercial incinerators with short stacks was s imi lar to that achieved by larger biomass (wood waste) and MSW combustors . Plants with larger capacities general ly have tal l er bui ldings, requiring correspondingly higher stacks . Dilution factors can be greatly increased by employing higher stacks, and by l ocating the stacks farther from ta l l bui ldings .
F igure 7 - Dilution factors for combustors vs . stack height .
Relationship Between Waste Composition and Environmental I mpact F loyd Hasselriis Draft of July 9 , 19 9 2 21
comparing Ground Level Concentrations with Acceptable l evels
After determining the ground l evel concentration (GLC) , hea l th ef fect studies can be carried out . The US EPA and various states have e stablished acceptabl e ground l evel concentrations (AGLC) for harmful and toxic substances , established by hea l th authorities and based on various times of exposure . When the predicted GLCs are compared with AGLCs , it is usua l ly found that the GLCs are a few percent or less of the AGLC standards and can be considered to be safe; it not , reductions in stack emissions o r improvements stack height or configuration may be needed . Modification of the waste stream is sometimes a practical and economic alternative . (Hassel riis , 19 9 2)
A l l of the reductions discussed above may be considered in order to decide which are practical and most economica l . The choice s must be based on the specific conditions of the site , the wa ste , and the combustion and emission control s available .
RELATING INPUT TO OUTPUT
I n summary , the above review shows that each step provides a potential for control ling or reducing the environmental and hea l th e f f ect of stack emis sions . The potential of each of the various steps is unique , and quite different . The fol l owing is a rough summary of the potentia l s of each step , based on the above analyses :
Source reduction and substitution :
The chlorine in medical waste can be substantial ly reduc ed by avoiding the purchase of PVC plastics . I t may be possib l e to reduce HCI emis sions from as high as 1 5 0 0 ppmv to 5 0 to 1 0 0 ppmv by this method , a 15 to 3 0 -time reduction .
Data presented indicates that the cadmium in MSW and MW could perhaps be cut in hal f , reducing it from the typical 1.6 ppm of waste to less than 0 . 8 ppm by eliminating cadmium f rom the plastic s . Substituting for the l ead in plastics might reduce total l ead by about 2 5%.
I mproving combustion :
Reductions in hydrocarbon emissions from typical l eve l s of 40 ppm to 4 ppm or l e s s can be achieved with good operation and supervision of combustion . Uncontrol l ed emis sions of dioxins and furans have been reduced from formerly typical l evel s exceeding
Rel ationship Between Waste Composition and Environmental Impact F loyd Has s e l riis Draft of July 9, 19 9 2 2 2
1 0 0 0 ng/m3 to about 5 0 ng/m3 by operating in a more ideal range of temperature and excess oxygen.
Emi ssion contro l s :
Emis sion contro l s can reduce emis sions o f particulate from uncontrol l ed l evel s of as high as 0.1 to 3 grains per cubic foot (gr/dscf) to 0.0 0 5 to 0.0 01 gr/dscf , a reduction of 1 0 0 to 6 0 0 times. wet scrubbers and scrubber/baghouse systems are capabl e o f reducing HCl emissions by 9 5 to 9 9% , a reduction factor of 2 0 t o 1 0 0 times. They can a l so reduce emi ssions of heavy metal s by factors exceeding 9 9% , a loo-time reduction. Dioxins and furans reductions to less than 1 ng/m3 have been achieved by emission control s.
Dispersion of stack gases:
The gases l eaving the stack may be di spersed by factors ranging from 5 0 0 to 5 0 0 0 times for short stacks near high buildings to 2 5 0 , 0 0 0 times or more by raising the stack or f i nding a more favorabl e location. The potential for improving dispersion factors may therefore range from 5 0 to 5 0 0 times.
CONCLUSIONS
s tudy of data on emissions from municipal and medical waste incinerators shows that whi l e the pol lutants of concern are components of the waste , there are many important factors whi ch determine how much of these pol lutants can enter the atmosphere , and how much they wi l l af fect ground l evel concentrations and represent environmental and health concerns.
S ome of the potential po l l utants in the waste can be avoided by not putting them in the products or purchasing them in the first place , such as highly chlorinated plastics and solvents. Other pol lutants , such as l ead and cadmium , can be reduced by restricting their use as fil l ers and colorants in plastic s , textiles and paper.
When wastes are burned , furnace temperatures , combustion air distribution , lifting velocities and other factors can be adjusted to substantia l ly reduce the quantities of particulate lifted f rom the combustion system into f lyash. High particulate l i fting i s associated with the production of dioxins and furans in the post-combustion regions. Excessive furnace temperatures i ncrease votatile high heavy metal emi ssions.
The particulate , acid ga ses , heavy meta l s and organics which are emitted from the combustion proces s , can be removed f rom the gases by condensation and absorption so that they can be
Relationship Between Waste Composition and Environmental Impact F loyd Has s e l riis Dra ft of July 9 , 1 9 9 2 2 3
collected by a wet scrubber , baghouse , or other emission control device . Low temperatures , below 2 5 0°F to 3 0 0°F , are effective in condensing these pollutants , including the relatively di fficultto-remove sulfur dioxide . Mercury can be reduced by adding carbon or other reagents .
Di sposal of ash and scrubber residues can be managed so as to be envi ronmentally acceptable , but care must be taken to deal with soluble heavy metals .
After taking advantage of the above opportunities to reduce emi s sions , di spersion of the resulting emi ssions from the stack can be further inc reased by employing favorable building configurations and stack heights so that calculated concentrations at ground level or at nearby receptors will be only a few percent of concentrations considered acceptable by regulators and health authorities .
REFERENCES
Bergvall , G . , and Jan Hult , "Technology , Economics and Environmental Effects of Solid waste Treatment , DRAV Number 3 3 , Statens naturvardsverk , Solna , Sweden .
Blizard , G . F . , Jr . , and R . J . Tidona , " Design , I nstallation and Start-up of a Rotary Kiln Hospital waste I ncineration system with Heat Recovery and S FDA/FF APC System , " Presented at the 1 1 th I nternational I ncineration Conference , Albuquerque , NW, May 1 9 9 2 .
Brady , J . D . , " Recent Developments in Pollution Control Systems for Chemical and I n fectious Waste Incinerators , " Mid-West Regional AIChE Meeting , st . Loui s , MO , February 1 9 9 1 .
Brown , H . L . , " Thomas Jefferson University Hospital Waste Characterization Study , " Drexel University , Philadelphia , PA , August 1 9 8 9 .
CARB , "Technical Support Document to Proposed Dioxins Control Measures for Medical Waste I ncinerators , " Cali fornia Air Resources Board , May 1 9 9 0 .
Durkee , K . R . and J . A . Eddinger , " Status of EPA Regulatory Development Program for Medical waste I ncinerators --Results o f Emi ss ion Test Program , " Presented a t the 1 1 th I nternational I ncineration Conference , Albuquerque , NW, May 1 9 9 2 .
GBB , Municipal solid waste sampling studies reported by Gershman , Brickner and Bratton , I nc . , Falls Church , Virginia .
Relationship Between Waste Composition and Environmental Impact Floyd Has selriis Draft of July 9 , 1 9 9 2 2 4
Getz , Norman P . and C . Kenna Amos , Jr . , " Demonstrated and I nnovative Control Technologies for Lead , Cadmium and Mercury f rom Muni cipal waste Combustors , " Paper No . 9 2 - 4 0 . 0 7 , presented at the 8 5 th Annua l Meeting of the Air and waste Management Association , Kansas City , June 19 9 2 .
Gottshink , L . , et aI , " Waste Paper study , " I nstitute for Papermaking , " Technical Highschool , Darmstadt , FRG , April 1 9 8 6 .
Green , Alex E. , Ed. , "Medical Waste Incineration and Pollution Prevention , " Van Nostrand Reinhold , New York , 1 9 9 2 .
Gullett , B . K . , K . R . Bruce and L . O . Beach , " Formation Mechanisms of Chlorinated Organics and Impacts of Sorbent I njection , " I nternational Conference on Municipal Waste Combustion , Hollywood F lorida , April 19 8 9 .
Hagenmaier , H . et al , " catalytic ef fects of fly ash from waste incineration fac i l ities on formation and decomposition of PCDDs and PCDFs , " I nternational symposium on Dioxins and Related Compounds , Fukuoka 19 8 6 , and Envi ronmental Science and Technology, 19 8 7 .
Has selriis , F . , " Refuse-derived Fuel Processing , " Butterworths , Stoneham , MA , 19 8 4 . (Out of print; available from author)
Hassel riis , F . , " Guidance Relative to Combustion of Municipal S olid Waste , " prepared for New York State Department of Environmental Conservation , 19 8 5 .
Has s elrii s , F . , "Minimizing refuse combustion emi ssions by combustion control , alkaline reagents , condensation and partic ulate Remova l , " Synergy/Power Sympos ium o n Energy from S olid Wastes , Washington , October , 19 8 6 .
Has s elrii s , F . , " Optimization of combustion Condition s to Minimize Dioxin Emissions , " waste Management & Research , Volume 5 , 1 9 8 7 .
Has s elrii s , F . , " Relationships Between Variability of Emi s sions and Residues from combustion of Municipal S olid Waste and waste Compos ition and Combustion Parameters , " I nternational Con ference on Muni cipal Waste Combustion , Hollywood Florida , April 19 8 9 , A&WMA VIP-19 .
Has s elrii s , F . , " Relationship Between Waste Composition and Environmental Impact , " 8 3 rd Annual Meeting of Air & Waste Management Association , June , 19 9 0 , Paper # 9 0 - 3 8 . 2 .
Has s elrii s , F . , " Environmental and Heal th Risk Analysi s o f
Relationship Between Waste Composition and Environmental Impact Floyd Ha sselriis Draft of July 9 , 19 9 2 2 5
Medical waste I ncinerators Employing state of the Art Emi s s ion Control s , " 8 4 rd Annual Meeting of Air & waste Management Association , June , 1 9 9 1 , Paper # 9 1 - 3 0 . 3 .
Has s e l r i i s , F . , " Effect of waste stream Modification and other Factors on Ground Level Concentrations Resulting From Medical waste I nc ineration Compared with Acceptabl e Air Quality , " 8 5 th Annual Meeting of Ai r waste Management Association , June , 1 9 9 1 , Paper # 9 2 - 2 3 . 0 3 .
Has s e l ri i s , F . , " Effect of waste composition and charging Cycl e o n Combustion Efficiency o f Medical and other S o l id waste Combustors , " 1 9 9 2 ASME National Solid waste Processing Con ference , Detroit , MI , May 1 9 9 2 , ASME , New York .
Hickman , D . C . , D . P . Y . Chang and H . Glasser , " Cadmium and Lead in Bio-medical Waste I ncinerators , " AWMA Conference , June 1 9 8 9 .
Jenkins , A . , " Eva luation Test on a Hospital Refuse Incinerator at Cedar s S inai Medical Center , Los Angeles , CA , " Cal i fornia Air Resources Board Test Report Number S S - 8 7 - 1 1 , 1 9 8 7 .
Kerstetter , James and John Kim Lyons , " Heavy Metal Concentration in S e l ected Paper Samples , " Washington state Energy Office , WA , June 1 9 8 9 .
Ki lgroe , J . D . , W . S . Lanier and T . Rob von Alten , " Development of Good combustion Practice for Municipal waste Combustors , " Proc . of 1 9 9 2 ASME National waste Processing Conference , Detroit , 1 9 9 2 , ASME , New York .
N I TEP , " The National I ncinerator Testing and Eva luation Program : Two-Stage combustion { Prince Edward I s land ) , " Environment Canada Report EPS 3 /UP/ 1 September , 1 9 8 5 .
N I TEP , " The National I ncinerator Testing and Evaluation Program : Air Pol lution Control Technol ogy , " Environment Canada Report EPS 3 /UP/ 2 , S eptember , 1 9 8 6 .
NITEP , " The National I ncinerator Testing and Evaluation Program : Environmental Characterization of Mass Burning Incinerator T echnology at Quebec city , " Environment Canada , Report EPS 3 /UP/5 , June 1 9 8 8 .
Torke l son , Peter J . , " Report on the As sessment of Operation and Emi ssions of On- site Medical Waste Incinerators , " Minnesota Pol lution Control "Agency , Air Qual ity Division , December 1 9 9 1 .
Relationship Between Waste Composition and Environmenta l Impact F loyd Hasselriis Draft of July 9 , 1 9 9 2 2 6
Torke l son , Peter J . , "Medical waste streams and Emi s sions of Three Minnesota Hospital I ncinerators , " Paper No . 9 2 - 2 . 0 7 , presented at the 85th Annual Meeting of the Ai r and waste Management Association , Kansas City , June 1 9 9 2 .
Turner , Mark B . et al , " The results of EPA ' s Emi ssion Test Program to Support the New Source Performance Standard for Medical waste I ncinerators , " Paper No . 9 2 - 2 . 0 6 , presented at the 8 5 th Annua l Meeting of the Air and waste Management As sociation , Kansas City , June 1 9 9 2 .
USEPA , " Municipal waste Combustion Study : Emission Data Base for Muni cipal waste Combustors , " prepared by Midwest Research I nstitute for u . S . Environmental Protection Agency , January , 1 9 8 7 .
USEPA , " Characterization of Products containing Lead and Cadmium in Muni cipal S o l id waste in the united states 1 9 7 0 to 2 0 0 0 , " prepared by Franklyn Associates , EPA/ 5 3 0 -SW- 8 9 - 0 1 5 C , 1 9 8 9 , USEPA Office o f S o l id Waste , Washington , DC .
Vogg , H . , M . Metz and L . Steiglitz , Recent Findings on the Formation and Decomposition of PCDD/PCDF in Municipal S o l id Waste I nc ineration , waste Management and Research , Vol . 5 , No . 3 , 1 9 8 7 .
Relationship Between Waste Composition and Environmenta l Impact F loyd Ha sselriis Draft of July 9 , 1 9 9 2 2 7
o
Q U E B EC CITY TESTS PERCENT CADMI U M I N FLYASH
� 0.025--.-------------------------, o w ...J ...J o o :c (J') «
