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ANNEX 6: RANGE OF VALUES FOR INCINERATOR EMISSIONS
Incinerator emissions in our modelling exercise are based on a small number of studies. This is a difficult choice to make since incinerator emissions will vary over time. Even when one resorts to looking at targets in the proposed Waste Incineration Directive, one finds targets specified over different averaging periods. Ideally, one's choice of emission values reflects knowledge of the nature of the effect. As we have discussed in the main report, these themselves will be the subjects of some uncertainty so that we may not be able to be so sanguine as to assume that short events of higher exposure are unimportant in causing specific effects. We have compared a small number of quoted sources with the limits set in the Directive. At the low end, if quoted sources give lower values, we have used them. At the high end, if quoted sources exceed the highest Directive target (which will relate to the shortest averaging period) we have used. If all quoted sources give lower values, even at the maximum range, we have used the highest quoted value.
For comparison, we show rounded figures for the 'New Incinerator' as specified in the Environment Agency WISARD demonstration disk (and some appropriate caveats are specified therein). The High and Low values are taken from the MAX and MIN values specified in the demonstration disk (which it suggests should be used for sensitivity analysis only). There is considerable divergence for CO, VOCs, SO2 and cadmium. Given the actual data used by Entec (1999b) in respect of CO, we believe our figures are defensible. Even the Maximum figures for retrofitted incinerators in the WISARD demonstration are far in excess of the Entec (1999b) figure for Tyseley. Almost identical comments can be made in respect of the figures that the demonstration disk for WISARD quotes for SOx. From the point of view of the valuation work, it is the divergence in the SO2 figure that is most critical. Figures for 'dust' in the WISARD demonstration lie within the same range as that we have used for particulates.
|
Pollutant |
Units |
High or Low? |
Values |
Comment on values used |
WISARD (New incinerator) |
|
Gas Volume |
m3 11% O2 dry |
High |
5,000 |
|
5,200 |
|
|
|
Low |
5,500 |
|
5,200 |
|
Particulates |
mg/Nm3 |
Low |
5 |
Lower than Directive limits |
figure given for 'dust' |
|
|
|
High |
30 |
Directive limit for 30 min averages. Carroll's (1995) high end of range is higher. Entec (1999b) quote actual figures for Tyseley of 28.5 (hourly average) |
figure given for 'dust' |
|
CO |
mg/Nm3 |
Low |
40 |
Lower than lowest Directive limit (50 for daily average). Chosen as high end of range from Agency Guidance. Environment Agency guidance has lower targets. |
9 |
|
|
|
High |
150 |
Highest Directive limit (for 95% of 10 minute averages). Entec (1999b) quote actual figures for Tyseley of 104.5 for hourly average |
12 |
|
VOCs |
mg/Nm3 |
Low |
3 |
Low value is the high end of Agency guidance |
0.5 |
|
|
|
High |
20 |
High end is the highest Directive limit |
0.5 |
|
Arsenic |
mg/Nm3 |
Low |
0.08 |
WISARD demonstration disc, low value for new incinerator (for sensitivity analysis purposes) |
0.08 |
|
|
|
High |
0.4 |
Half the lead - arsenic figure used in CSERGE et al (1993) |
0.12 |
|
Cadmium |
mg/Nm3 |
Low |
0.05 |
From Carroll (1995) The Directive specifies limits for Cadmium and Thallium combined. |
0.004 |
|
|
|
High |
0.2 |
From Carroll (1995). The Directive specifies limits for Cadmium and Thallium combined. |
0.008 |
|
Mercury |
mg/Nm3 |
Low |
0.03 |
Below lowest Directive limit of 0.05 (30 minute averages). |
0.02 |
|
|
|
High |
0.05 |
Highest Directive limit. Note that high end of ranges quoted in Carroll (1995) and CSERGE et al exceed this value |
0.04 |
|
HCl |
mg/Nm3 |
Low |
8 |
Low figure from CSERGE et al (1993) - below lowest Directive limit of 10 for daily averages |
18.6 |
|
|
|
High |
60 |
Highest Directive limit (for 30 minute averages). High end of Carroll (1995) exceeds this |
40 |
|
SO2 |
mg/Nm3 |
Low |
40 |
Low end of CSERGE et al (1993) and Carroll (1995). Below lowest Directive limit of 50 (for daily averages) |
14 (SOx) |
|
|
|
High |
200 |
Highest Directive limit (for 30 minute averages) - exceeded by high end of CSERGE et al (1993) and Carroll (1995). Entec (1999b) figures for hourly averages from Tyseley were 144 in 1997 and 125 in 1998. |
21 (SOx) |
|
HF |
mg/Nm3 |
Low |
0.08 |
Low end of CSERGE et al (1993). Below lowest Directive limit of 1 (for daily average) |
0.14 |
|
|
|
High |
2 |
High end of Carroll (1995) (below highest Directive limit of 4 (for 30 minute averages) |
1.33 |
|
NOx |
mg/Nm3 |
Low |
160 |
The Directive has targets for NOx as NO2, but not for total NOx. This value is the low end of CSERGE et al (1993). It is below the lowest NO2 target of 200 (for daily averages) |
245 |
|
|
|
High |
350 |
Higher end of Carroll (1995). This is lower than the highest Directive target for NOx as NO2 of 400 (for 30 minute averages). Entec (1999b) give actual figures for Tyseley of 332 in 1997, 321 in 1998 |
279 |
|
Dioxin ITEQ |
mg/Nm3 |
Low |
0.0000000 8 |
Low end is from CSERGE et al (1993) |
6E-08 |
|
|
|
High |
0.0000001 |
High end is the Directive target (for 6-8 hr averages). Higher end of range in CSERGE et al (1993) exceeds this. |
1.1E-07 |
|
Other heavy metals |
mg/Nm3 |
Low |
0.4 |
Low end is half the lead arsenic content in CSERGE et al (1993) - see above |
0.09 |
|
|
|
High |
0.5 |
High end is the Directive limit |
0.12 |