Environmental Engineering Reference
In-Depth Information
The values for correction factors used in the model are mostly default values suggested
by IPCC, as mentioned below:
Degradable Organic Carbon (
DOC
)
Degradable organic carbon is the fraction of the organic carbon present in the waste that
will degrade under anaerobic conditions. However, only fraction of the DOC is decomposable
in nature (
j
DOC
). Hence, decomposable degradable organic carbon by mass (
DDOC
)
f
m
is:
∗=
(4)
Where,
W
is the mass of the waste deposited in the landfill in the given year and MCF is
the methane correction factor for aerobic decomposition of waste.
The relationship between Methane generation potential (
DDOC
W
DOC
∗
DOC
∗
MCF
m
f
L
) used in LandGEM and
DDOC
, as described in IPCC (2006), is:
m
16
L
=
DDOC
∗
F
∗
(5)
0
m
12
Where,
F
= CH
4
concentration in LFG and 16/12 is the ratio of molecular weight of CH
4
and Carbon.
MSW contains different types of waste namely food waste, garden waste, paper, wood,
textiles, plastics etc. Different waste types contain different amount of degradable organic
carbon (DOC). As per IPCC FOD model, waste composition of MSW is classified into six
categories as shown in Table 8.
Decay rate/methane generation rate (
k
)
As already mentioned in the previous section, IPCC has mentioned two alternatives to
use the value of k for estimation of gas potential. In this model, the waste composition option
is used where degradation of different types of waste is assumed to be independent of each
other. IPCC 2006 has recommended default k values for different waste categories dependent
upon the location of the landfill site and its climatic conditions as shown in Table 9.
Table 8. IPCC Default DOC Value (In Fraction) For Different Waste Type
Type of Waste
DOC
j
Wood and wood products, A
0.430
Pulp, paper and cardboard, B
0.400
Food, food waste, beverages and tobacco, C
0.150
Textiles, D
0.240
Garden, yard and park waste, E
0.200
Glass, plastic, metal other inert, F
0
Source: IPCC, 2006
