Environmental Engineering Reference
In-Depth Information
Table 9. IPCC Default of K Used in IPCC in IPCC FOD Modeling
Type of Waste
K
Wood and wood products, A
0.035
Pulp, paper and cardboard, B
0.07
Food, food waste, beverages and tobacco, C
0.40
Textiles, D
0.07
Garden, yard and park waste, E
0.17
Glass, plastic, metal other inert, F
0
Source: IPCC, 2006
D. Regression Models
The EPA Air and Energy Engineering Research Laboratory (AEERL) began a research
program in 1990 with the goal of improving global landfill methane emission estimates. Part
of this program was a field study to gather information that was used to develop an empirical
model of methane emissions. Twenty-one US landfills with gas recovery systems were
included in the study. Site-specific information included average methane recovery rate,
landfill size, refuse mass, average age of the refuse, and climate. A correlation analysis
showed that refuse mass was positively linearly correlated with landfill depth, volume, area,
and well depth. Regression analysis of the methane recovery rate on depth, refuse mass, and
volume was significant, but depth was the best predictive variable (R
2
= 0.53). Refuse mass
was nearly as good (R
2
= 0.5). None of the climate variables (precipitation, average
temperature, dew point) correlated well with the methane recovery rate. Much of the
variability in methane recovery remains unexplained, and is likely due to between-site
differences in landfill construction, operation, and refuse composition. A model for global
landfill emissions estimation was proposed based on this data. A simple model correlating
refuse mass to methane recovery with a zero intercept was developed:
Q
methane
=
4
.
52
w
(6)
Where;
= Methane
flow rate (m
3
/min)
Q
methane
w
= mass of refuse (Mg)
E- Theoretical Models
The theoretical CH
4
generation capacity (
L
) can be determined by a stoichiometric
method that is based on a gross empirical formula representing the chemical composition of
the waste. If a waste contains carbon, hydrogen, oxygen, nitrogen and sulfur (represented by
C
a
H
b
O
c
N
d
S
e
), its decomposition to gas is shown as:
C H O N S
®
vCH
+
wCO
+
xN
+
yNH
+
zH S
+
humus
(7)
abcde
4
2
2
3
2
