Incineration: The British experience

Chemosphere, Vol.20, Nos.lO-12, Printed in Great Britain

pp 1785-1791,

1990

0 0 4 5 - 6 5 3 5 / 9 0 $3.OO + .OO P e r g a m o n Press plc

INCINERATION: THE BRITISH EXPERIENCE R S Brown, K Pettit, K J Mundy, P W Jones Rechem Internationa] Limited Hardley, Hythe Southampton S04 6ZA UK and W Nob]e Edmonton So|id Waste Incineration Plant North London Waste Regulatory Authority Angel Road Edmonton London UK ABSTRACT The emissions of polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) from a number of c l i n i c a l and municipal refuse incinerators of varying sizes have been investigated w i t h i n the United Kingdom. The methodology employed w i l l be described and the range of PCDD and PCDF emissions observed w i l l be contrasted with those from a large chemical i n c i n e r a t i o n plant. The results from the analysis of flyashes for PCDDs and PCDFs from various plants are also shown.

KEYWORDS Dioxin, furan, refuse, i n c i n e r a t i o n , emissions.

INTRODUCTION Concern into chlorinated aromatic hydrocarbon emissions has slowly been growing in the United Kingdom. In the UK combustion processes are a major source of polychlorinated dibenzo-pdioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) (Dioxins in the Environment, 1989). This paper describes the range of levels found for t h i r t e e n e x i s t i n g incinerators in the UK, and compares them with standards in Sweden and with the emission levels from the Rechem waste treatment f a c i l i t y (Jones, e t . a l . , 1989). A b r i e f description of the sampling protocol employed in most of the studies is also described.

EXPERIMENTAL Sampling Stack gas samples were collected using an Andersen Universal Stack Sampling System (USA) complying with the United States Environmental Protection Agencies Modified Method Five (MM5) Protocol, Fig. I. The sampling was performed for PCDDs and PCDFs using internal sampling recovery standards (Table I ) which were spiked onto the p a r t i c u l a t e f i l t e r p r i o r to sampling of the stack gases. The sampling t r a i n was optimised to obtain samples i s o k i n e t i c a l l y , and traversed across the duct according to 8S 3405 : 1983. The MM5 sampling t r a i n was employed to sample between I and 2 m3, with the probe thermostatted to the stack gas temperature and the f i l t e r u n i t at II0OC : the XAD-2 resin trap and toluene impingers were cooled using r e c i r c u l a t e d water. The samples were obtained, where possible in t r i p l i c a t e to account for v a r i a t i o n s in feed stock. This was e s p e c i a l l y important f o r c l i n i c a l and municipal i n c i n e r a t o r s where the nature of the waste was constantly varying.

1785

1786

FUB HCL~

~F

JAI I_

imm~u~z

IY'~YALV£

~Y/~JJM t~[

O~r&k~Pt'IIO~ AmTlSfI

FIGURE I - SCHEMATICOFTHE STACK SAMPLINGTRAIN

TABLE 1 - 13C POLYCHLORINATED DIBENZO-P-DIOXIN AND DIBENZOFURAN STANDARDS

FILTER SPIKE

2,3,7,8-TCDD 2,3,7,8-TCDF

5ng 5ng

1,2,3,7,8-PCDD 2,3,4,7,8-PCDF

5ng 5ng

1,2,3,6,7,8-HxCDD

5ng

1,2,3,4,7,8-HxCDD

5ng

1,2,3,7,8,9-HxCDF

5ng

1,2,3,4,6,7,8-HpCDD

5rig

1,2,3,4,6,7,8-HpCDF

5ng

OCDD

lOng

Analysis The stack sample f i l t e r , XAD-2, toluene impinger liquid, and probe washings, were individually spiked with one quarter of the sampling recovery standard (Table 2) and Soxhlet extracted with toluene where appropriate for sixteen hours.

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TABLE 2 - 13C POLYCHLORINATEDDIBENZO-P-DIOXINS AND DIBENZOFURANSSTANDARDS

SAMPLING RECOVERYSPIKE

1,2,3,7,8-PCDF

5rig

1,2,3,/,8,9-HxCDD

5ng

2,3,4,6,7,8-HxCDF

5ng

1,2,3,4,7,8,9-HpCDF

5ng

The toluene e x t r a c t s were combined and concentrated by r o t a r y evaporation (55oc). Interferences were eliminated according to a method previously described (Jones e t . a l . , 1989). A f i n a l e x t r a c t i o n recovery spike (Table 3) was added to allow sampling and extraction efficiencies to be calculated for regulatory purposes when required (Jansson et.alo, 1987). The samples were analysed by high resolution gas chromatography and mass spectrometry. TABLE 3 - 13C POLYCHLORINATEDDIBENZO-P-DIOXIN AND DIBENZOFURANSTANDARDS

EXTRACTION RECOVERYSPIKE

1,2,3,4-TCDD (13C6)

5ng

1,2,3,6,7,8-HxCDF 1,2,3,4,7,8-HxCDF

5ng 5ng

Instrumental:

VG 70S/11-250J Mass Spectrometer : HP5850 Gas Chromatograph.

Source:

Dedicated El Source.

Injector:

Grob Type Splitless Injector and HP7673A Autoinjector.

MS Conditions:

8kV, IO,O00RP (10% Valley Definition).

Capillary Column:

DB-5 60m x O.32mm id, Scientific.

Temp. Programme:

I n i t i a l temperature 200oc/2 min; ramp 5oC/min to 220oc/16min; ramp 5oC/min to 235oC/7min and ramp 5oc/min to final temperature 330oc for 5 min.

Helium Flow:

I - 2 ml/min.

df = 0.25~

13C standards supplied by Promochem, St Albans, Hefts, UK.

column supplied by J & W

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RESULTS AND DISCUSSION

The i n c i n e r a t o r s investigated may be divided into four broad categories:

Municipal, Clinical, Chemical and Others The category 'others' include waste cardboard i n c i n e r a t o r s , waste paper i n c i n e r a t o r s , heating b o i l e r s with o i l / s o l v e n t f u e l . The f a c i l i t i e s are usually small with tonnages of I tonne of waste per day. Municipal Incinerators vary in t h i s study from
ng/m3 CLINICAL

MUNICIPAL

OTHERS

CHEMICAL

2,3,7,8-TCDF

2-110

0.2-145

0.03-21

<0.02

TCDF

52-550

0.4-280

0.2-176

0.17

2,3,7,8-TCDD

0.1-25

0.1-26

0.06-24

<0.01

TCDD

2-118

0.2-205

0.06-24

0.06

PCDF

16-517

2-463

0.1-65

0.02

PCDD

7-275

0.7-387

0.1-33

0.24

HxCDF

27-2120

0.1-400

0.1-58

0.04

HxCDD

0.2-175

0.04-285

0.!-19

0.03

HpCDF

21-600

4-855

0.2-55

0.03

HpCDD

5-124

2-322

0.8-120

0.03

OCDF

1-51

1-80

0.1-31

0.04

OCDD

1-42

1-252

4-410

0.03

The Edmonton Solid Waste Plant, a sophisticated municipal i n c i n e r a t o r with energy recovery used to generate e l e c t r i c i t y (upto 25MW), has by most UK standards a high level of emission arrestment equipment (see Fig. 2). I t is an example of a well operated and well maintained municipal waste i n c i n e r a t i o n f a c i l i t y .

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i

i ~e

i i I V A 0 0 . G { N [ RAIQR I~ ¢ O N I X N S ( n ~o JNOUCCD~ i ~ M I C~EING ~ N T ~I C WeUMp l~ T R A N I r O A M ( R ~J ~XIA~CI~N~ N ? ~1 L P. M ( A T [ A & O~AIN¢ ~ L { R ~s C ~ A [ ~ * v O ~ ufT ~ r

wo~is.o~

FIGURE 2 - EDMONTON SOLID WASTE INCINERATION PLANT

The Plant, which is rated at >10 tonnes/hour of municipal waste, has been found to achieve good emission levels of PCDDs and PCDFs (Table 5). TABLE 5 - STACK EMISSIONS FROM EDMONTON MUNICIPAL REFUSE INCINERATOR

ng/m 3

2,3,7,8-TCDF TCDF 2,3,7,8-TCDD TCDD PCDF PCDD HxCDF HxCDD HxCDF BpCDD OCDF OCDD

0.4 - 0.8 2 - 5 0.1 0.2 - 0.23 2 - 3 0.7 - 2 <0.1 - 2 0.04- 0.2 47 - 854 2 -

3

1 - 2 1 - 4

This i n c i n e r a t o r has an estimated t o x i c equivalent of about 4 ng/m3 and represents one of the best i n s t a l l a t i o n s , excluding s p e c i a l i s t chemical incinerators w i t h i n the UK.

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The proportion of Plants w i t h i n the UK which have been monitored by the Group and meet the Swedish standards [0.1 ng/m3 TEQ (Eadon) for new i n c i n e r a t o r s , and 0.5 - 2.0 ng/m3 TEQ (Eadon) f o r e x i s t i n g i n c i n e r a t o r s ] is shown below - Fig. 3. The chemical waste i n c i n e r a t o r studied (Rechem, Pontypool) showed the least d i o x i n / f u r a n emissions (0.2 ng/m3 TEQ, Eadon), which might be expected in view of the advanced stack gas cleaning, which includes both scrubber and e l e c t r o s t a t i c p r e c i p i t a t o r s .

I ] 0.I-0.5 • ~

-I0

]

10-50

] 50-iO0 ! 00+

ngl'mJ(eadon)

FIGURE 3 - THE PROPORTION OF INCINERATORS IN THE UK EMITTING PCDOs AND PCDFs AT VARIOUS LEVELS

At many of the i n c i n e r a t o r s monitored, flyash and/or grate ashes are combined and sent for l a n d f i l l or disposed of in a special manner. These ashes are often handled with the minimum of protection and our studies have shown wide v a r i a t i o n s in the levels of PCDDs and PCDFs present (Table 6), but our overall conclusion, except where the levels are at t h e i r lowest, is that the ashes could c o n s t i t u t e a s i g n i f i c a n t occupational hazard to personnel working in these f a c i l i t i e s . TABLE 6 - LEVELS OF PCDDs AND PCDFs FOUND ON FLYASH AND GRATE RESIDUES

ng/g 2,3,7,8-TCDF TCDF 2,3,7,8-TCDD TCDD PCDF PCDD HxCDF HxCDD HpCDF HpCDD OCDD OCDF

0.9 2.0 10 12
-

90 480 100 360 530 2010 900 1620 490 1350 680 80

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The levels found in ash residues from clinical waste f a c i l i t i e s often contain much higher levels of PCDDs and PCDFs and this is due to the high level of PVCs, plastics, etc. which are disposed of by these Plants. These hospital f a c i l i t i e s in the UK have t r a d i t i o n a l l y been exempted from a number of aspects of legislative control. ACKNOWLEDGEMENTS

We are grateful to Mrs Joan Ford for help in the typographical preparation of this Paper. REFERENCES

Dioxins in the Environment (1989), Pollution Paper 27, 1989, p11. (ISBN:O 11 7522295),HMS0. Jones, P. W., Brown, R. S. and Mundy, K. J. (1989). Environmental Assessment at and around a Chemical Treatment F a c i l i t y I - Measurements on PCDFs and PCDDs, Chemosphere, 19, 381-386. Jansson, B. and Bergvall, G. (1987), Recommended Methodology for Measurements of PCDDs and PCDF in the Nordic Countries. Paper presented to the Emission of Trace Organics from Municipal Solid Waste Incinerators, Specialised Seminar, Copenhagen, 22-22 Jan. 1989.