Environmental Engineering Reference
In-Depth Information
12
PM>10
PM2.5-10
10
PM2.5
8
6
4
2
0
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
Year
Fig. 3.15 Variation of PM values for dust emissions measured at the cement factory in Harbin
(China) [
58
]
All municipal solid waste (MSW) incinerators are equipped with bag filters that
retain particulate matter. In Great Britain, such incinerators contribute to atmo-
spheric pollution with 0.042 % of the total PM
2.5
emissions [
62
].
Some studies show that, as far as municipal waste incineration is concerned,
ultrafine particulate matter PM
0.1-1
can have significant effects on health and the
environment. These studies hold that health risks are associated rather with the
number of ultrafine particles than with their mass [
63
-
65
].
Measurements of nanoparticles released at the stack of a municipal waste
incinerator with energy recovery located in Piacenza (Italy) [
63
] indicated that
no particles larger than 2.5
m in diameter were present in the emissions, but
about 65 % of the measured PM
2.5
emissions were sub-micrometre particles
(Fig.
3.16
). Particles larger or smaller than 100 nm had a relatively equal distribu-
tion [
63
,
64
].
The identification of the primary composition of stack emissions released by the
same incinerator led to the conclusion that the improved particle retention systems
were effective in removing 99.99 % of emissions, with similar efficiency in
reducing particles of smaller diameter [
65
].
It has been found that the boiling points of the elements present in the incinerated
waste are very important: higher boiling point elements like chromium were
identified in larger particles, while lower boiling point elements like arsenic and
cadmium were more present
μ
in ultrafine particles, making them more
dangerous [
65
].
Nevertheless, the conclusions that several authors from North America and
Japan and European researchers have drawn about the level of global pollution
with ultrafine particles are unanimous: in the general context of anthropogenic
