Chapter 5

Waste

5

WASTE

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.1

WasteChapter 5

CO-CHAIRS, EDITORS AND EXPERTS
Co-chairs of the Expert Meeting on Emissions f rom Waste
Taka Hiraishi (Japan) and Buruhani Nyenzi (Tanzania)

REVIEW EDITOR
José Domingos Miguez (Brazil)

Expert Group: CH 4 Emissions from Solid Waste Disposal
CO-CHAIRS
A.D. Bhide (India) and Riitta Pipatti (Finland)

AUTHORS OF BACKGROUND PAPER
Jens E. Frøiland Jensen (Norway) and Riitta Pipatti (Finland)

CONTRIBUTORS
Joao W. de Silva Alves (Brazil), Pascal Boeckx (Belgium), Keith Brown (UK), Robert Hoppaus (IPCC/OECD),Charles Jubb (Australia), Thomas Kerr (USA), Tore Kleffelgaard (Norway), Oswaldo Lucon (Brazil), Gerd
Mauschitz (Austria), Carmen Midaglia (Brazil), Martin Milton (UK), Michael Mondshine (USA), Hans Oonk
(Netherlands), Bostjan Paradiz (Slovenia), Katarzyna Steczko (Poland), Egle Novaes Teixeira (Brazil),
Sirintornthep Towprayoon (Thailand), and Irina Yesserkepova (Kazakhstan)Expert Group: CH 4 and N 2 O Emissions from Wastewater Handling
CO-CHAIRS
Michiel Doorn (Netherlands) and Faouzi Senhaji (Morocco)

AUTHOR OF BACKGROUND PAPER
John Hobson (UK)CONTRIBUTORSJuliana Adamkova (Slovak Republic), William Irving (USA), Scarlette Lara (Chile), Kenneth Olsen (Canada),
Karin Reuck (Chile), Ingvar Svensson (Sweden), and Sonia Manso Viera (Brazil)

Expert Group: Emissions from Waste Incineration
CO-CHAIRS
Martin Bigg (UK) and Newton Paciornik (Brazil)

AUTHOR OF BACKGROUND PAPER
Bernt Johnke (Germany)

CONTRIBUTORSJose Baldasano (Spain), Anke Herold (Germany), Andrej Kranjc (Slovenia), Jozef Kutas (Hungary) , Katarina
Mareckova (IPCC/OECD), and Kiyoto Tanabe (Japan)

5.2

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

Contents
5 WASTE
5.1 CH4 EMISSIONS FROM SOLID WASTE DISPOSAL SITES ...........................................................5.5
5.1.1

Methodological issues ...............................................................................................................5.5

5.1.2

Reporting and documentation..................................................................................................5.12

5.1.3

Inventory quality assurance/quality control (QA/QC).............................................................5.13

5.2 EMISSIONS FROM WASTEWATER HANDLING .........................................................................5.14
5.2.1

Methodological issues .............................................................................................................5.14

5.2.2

Reporting and documentation..................................................................................................5.23

5.2.3

Inventory quality assurance/quality control (QA/QC).............................................................5.23

5.3 EMISSIONS FROM WASTE INCINERATION................................................................................5.25
5.3.1

Methodological issues .............................................................................................................5.25

5.3.2

Reporting and documentation..................................................................................................5.30

5.3.3

Inventory quality assurance/quality control (QA/QC).............................................................5.31

REFERENCES ............................................................................................................................................5.32

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.3

WasteChapter 5

FiguresFigure 5.1

Decision Tree for CH4 Emissions from Solid Waste Disposal Sites ...............................5.6

Figure 5.2

Decision Tree for CH4 Emissions from Domestic Wastewater Handling......................5.15

Figure 5.3

Wastewater Flows, Treatment Systems, and Potential CH4 Emissions .........................5.17

Figure 5.4

Decision Tree for CH4 Emissions from Industrial Wastewater Handling......................5.20

Figure 5.5

Decision Tree for CO2 Emissions from Waste Incineration ..........................................5.26

Figure 5.6

Decision Tree for N2O Emissions from Waste Incineration ..........................................5.27

Tables

5.4

Table 5.1

SWDS Classification and Methane Correction Factors ...................................................5.9

Table 5.2

Estimates of Uncertainties Associated with the Default Parametersin the IPCC Default and FOD Methods for CH4 Emissions from SWDS .....................5.12

Table 5.3

Default Uncertainty Ranges for Domestic Wastewater .................................................5.19

Table 5.4

Industrial Wastewater Data............................................................................................ 5.22

Table 5.5

Default Uncertainty Ranges for Industrial Wastewater .................................................5.23

Table 5.6

Default Data for Estimation of CO2 Emissions from Waste Incineration......................5.29

Table 5.7

Emission Factors for N2O from Waste Incineration ......................................................5.30

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

5 WA S TE
5.1

CH4 EMISSIONS FROM SOLID WASTEDISPOSAL SITES

5.1.1

Methodological issues

Methane (CH4) is emitted during the anaerobic decomposition of organic waste disposed of in solid waste
disposal sites (SWDS). Organic waste decomposes at a diminishing rate and takes many years to decompose
completely.

5.1.1.1

C HOICE OF METHODThe Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC Guidelines) outline two
methods to estimate CH4 emissions from solid waste disposal sites, the default method (Tier 1) and the First
Order Decay (FOD) method (Tier 2). The main difference between the two methods is that the FOD method
produces a time-dependent emission profile that better reflects the true pattern of the degradation process overtime, whereas the default method is based on the assumption that all potential CH4 is released in the year thewaste is disposed of. The default method will give a reasonable annual estimate of actual emissions if the amountand composition of deposited waste have been constant or slowly varying over a period of several decades. If theamount or composition of waste disposed of at SWDS is changing more rapidly over time, however, the IPCC
default method will not provide an accurate trend. For example, if there is a reduction in the amount of carbon
deposited at SWDS, the default method will underestimate emissions and overestimate reductions.
The choice of a good practice method will depend on national circumstances. The decision tree in Figure 5.1,
Decision Tree for CH4 Emissions from Solid Waste Disposal Sites, illustrates the process of choosing among
methods. It is good practice to use the FOD method, if possible, because it more accurately reflects theemissions trend. The use of the FOD method requires data on current, as well as historic waste quantities,
composition and disposal practices for several decades. It is good practice to estimate this historical data, if suchdata are unavailable, when this is a key source category (see Chapter 7, Methodological Choice and
Recalculation) or if there have been significant changes in waste management practices.
The IPCC Guidelines do not provide default values or methods for the estimation of some key parameters
needed to use the FOD method. These data are very dependent on country-specific conditions, and currently
there are not enough data available to give reliable default values or methods for them. Inventory agencies areencouraged to obtain data from country-specific or regional research, because the inability of inventory agencies
to use the FOD method where otherwise indicated by good practice would reduce comparability between
national inventories. Inventory agencies selecting a method other than those described in the IPCC Guidelines
should justify their selection based on comparable or increased accuracy and completeness of the emissions
estimates.

5.1.1.2

C HOICE OF EMISSIO N FACTORS AND ACTI VI TY DATA

The discussion of good practice in the choice of activity data and emission factors is combined in this section,
due to the unique character of the emission estimation methods.

First Order Decay (FOD) method – Tier 2
The IPCC Guidelines (pp 6.10-6.11, Reference Manual) present the FOD method in three equations. The firstequation is to be used for an individual landfill, or possibly a group of specific landfills. A second equation,
suitable for national and regional estimates, calculates emissions from all solid waste deposited in SWDS in one
year. The purpose of the third equation is to estimate current annual emissions from waste disposal in current andprevious years.

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.5

WasteChapter 5

Figure 5.1

Decision Tree for CH4 Emissions from Solid Waste
Disposal Sites
Box 1

Are waste
disposal activity
data obtainable for thecurrent inventory
year?

Use IPCC default
values, per capita orother methods toestimate activity data

No

Estimate CH4
emissions using the
IPCC default
methodYes

Are waste
disposal activity data
available for previous
years?

Is this a
key source category?
(Note 1)

No

Yes

No

Yes

Box 2
Obtain or
estimate data on
historical changes insolid waste disposal

Estimate CH4
emissions using theFirst Order Decay(FOD) method

Note 1: A key source category is one that is prioritised within the national inventory system because its estimate has a significant
influence on a country’s total inventory of direct greenhouse gases in terms of the absolute level of emissions, the trend in emissions, orboth. (See Chapter 7, Methodological Choice and Recalculation, Section 7.2, Determining National Key Source Categories.)

The FOD method can be expressed equivalently by Equation 5.1 and Equation 5.2 below. Equation 5.1 is basedon the derivative of the general FOD equation (see p 6.10, Reference Manual, IPCC Guidelines) with t replacedby t – x, representing a normalisation factor that corrects for the fact that the evaluation for a single year is adiscrete time estimate rather than a continuous time estimate.
EQUATION 5.1
CH4 generated in year t (Gg/yr) =∑x [(A • k • MSWT (x) • MSWF (x) • L0(x))• e–k(t – x)]

for x = initial year to t
Where:
t = year of inventoryx = years for which input data should be added
A = (1 – e–k) / k ; normalisation factor which corrects the summationk = Methane generation rate constant (1/yr)
MSWT (x) = Total municipal solid waste (MSW) generated in year x (Gg/yr)
MSWF (x) = Fraction of MSW disposed at SWDS in year x
L0 (x) = Methane generation potential [MCF (x) • DOC (x) • DOCF • F • 16 / 12 (Gg CH4/Gg waste)]

5.6

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

MCF (x) = Methane correction factor in year x (fraction)
DOC (x) = Degradable organic carbon (DOC) in year x (fraction) (Gg C/Gg waste)
DOCF = Fraction of DOC dissimilated
F = Fraction by volume of CH4 in landfill gas
16 / 12 = Conversion from C to CH4
Sum the obtained results for all years (x).

EQUATION 5.2
CH4 emitted in year t (Gg/yr) = [CH4 generated in year t – R(t)] • (1 – OX)
Where:
R(t) = Recovered CH4 in inventory year t (Gg/yr)
OX = Oxidation factor (fraction)

Note that CH4 recovered (R(t)) must be subtracted from the amount generated before applying the oxidation
factor, because only landfill gas that is not captured is subject to oxidation in the upper layer of the landfill. In
addition, the unit for the methane generation potential should be expressed by weight (Gg CH4/Gg waste) andnot volume (m3/Mg waste) as currently written in the IPCC Guidelines in order to make the outcome of thedefault and FOD methods consistent.
The methane generation rate constant k that appears in the FOD method is related to the time taken for the DOC
in waste to decay to half its initial mass (the ‘half life’ or t½) as follows:k = ln2 / t½
The FOD method requires historical data on waste generation and management practices. In national inventories,
it is usually necessary to include data for 3 to 5 half lives in order to achieve an acceptably accurate result.
Changes in waste management practices (e.g. landfill covering/capping, leachate drainage improvement,
compacting, and prohibition of hazardous waste disposal together with MSW) should also be taken into accountwhen compiling historical data.
The value of k applicable to any single SWDS is determined by a large number of factors associated with thecomposition of the waste and the conditions at the site. Measurements from SWDS in the United States, theUnited Kingdom and the Netherlands support values for k in the range 0.03 to 0.2 per year (Oonk and Boom,
1995). The most rapid rates (k = 0.2, or a half life of about 3 years) are associated with high moisture conditions
and rapidly degradable material such as food waste. The slower decay rates (k = 0.03, or a half life of about 23
years) are associated with dry site conditions and slowly degradable waste such as wood or paper. Inventory
agencies are encouraged to establish k values or use their own k values if available and documented. In order toestimate k values, inventory agencies should determine the composition of waste disposed in SWDS over timeand study the conditions at the site(s). If no data on types of waste are available, a k value of 0.05 (a half life ofabout 14 years) is suggested as a default value.
Inventory agencies can estimate historical waste disposal and composition data, assuming it to be proportional topopulation, or urban population in cases where there has been no organised waste collection or disposal in rural
areas. Inventory agencies can use other relationships if better justified, and report the reasons for those choices.

Def ault method – Tier 1
The default method is based on the following equation:
EQUATION 5.3
CH4 emissions (Gg/yr) = [(MSWT • MSWF • L0 ) – R] • (1 – OX)
Where:MSWT = Total MSW generated (Gg/yr)
MSWF = Fraction of MSW disposed at SWDS

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.7

WasteChapter 5

L0 = Methane generation potential [MCF • DOC • DOCF • F • 16 / 12 (Gg CH4/Gg waste)]
MCF = Methane correction factor (fraction)
DOC = Degradable organic carbon [fraction (Gg C/Gg MSW)]DOCF = Fraction DOC dissimilated
F = Fraction by volume of CH4 in landfill gas
R = Recovered CH4 (Gg/yr)
OX = Oxidation factor (fraction)

Note that all of the model parameters can change over time, depending upon waste disposal trends and waste
management practices. Good practice is described below for each of the above model parameters.
To ta l mu n i ci pa l so li d w a st e (M SW T ) , a n d t he fra ctio n of M S W sen t to SWD S (M SW F )The use of the term municipal solid waste (MSW) may not accurately describe the types of waste disposed of in
SWDS. Inventory agencies should estimate the emissions from all types of solid waste material, including
industrial waste, sludge, construction and demolition waste and municipal waste, disposed of at SWDS. Data on
industrial waste may be difficult to obtain in many countries, but efforts to do so should be made. (Examples ofindustrial waste that can produce CH4 when disposed of include agro-food industrial waste,1 pulp and paper
waste and sludge, and waste from wood processing.) In many countries, national estimates of total waste
disposal may be available. National data are preferable, provided that inventory agencies document the datacollection method including the number of sites surveyed and the type of survey undertaken. If national data are
not available, inventory agencies can estimate data using default assumptions provided in Table 6-1, Reference
Manual of the IPCC Guidelines. This table provides default MSW generation and disposal rates for many
regions and countries. If no default values exist, inventory agencies can use expert judgement to estimate theseparameters using the values for countries with similar conditions. (Elements of comparability that inventory
agencies can consider are geography, population density, national income, and type and volume of industry.)
M ethane corr ectio n fa ctor (M CF) 2
The methane correction factor (MCF) accounts for the fact that unmanaged SWDS produce less CH4 from agiven amount of waste than managed SWDS, because a larger fraction of waste decomposes aerobically in the
top layers of unmanaged SWDS. The MCF in relation to solid waste management is specific to that area andshould be interpreted as the ‘waste management correction factor’ that reflects the management aspect it
encompasses. The term methane correction factor (MCF) in this context should not be confused with themethane conversion factor (MCF) referred to in the IPCC Guidelines for wastewater and livestock manure
management emissions.
The IPCC Guidelines present default values for MCF, which are presented in Table 5.1 below.

1 Avoid double counting with the Agriculture Sector.
2 Unmanaged SWDS cause serious local environmental and health problems, such as fire and explosion accidents, pollutionof surrounding air and waters, and outbreaks of pests and infections. However, the IPCC Guidelines and this report on Good
Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories (Good Practice Report) areintended to address greenhouse gas aspects only.

5.8

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

TABLE 5.1
SWDS CLASSIFICATION AND METHANE CORRECTION FACTORSType of Site

Methane Correction Factor (MCF)
Default Values

Managed a

1.0

Unmanaged – deep ( >5 m waste)

0.8

Unmanaged – shallow (<5 m waste)

0.4

Uncategorised SWDS

b

0.6

a

Managed SWDS must have controlled placement of waste (i.e. waste directed to specific deposition areas, a degree of control ofscavenging and a degree of control of fires) and will include some of the following: cover material, mechanical compacting or levellingof waste.
b
The default value of 0.6 for uncategorised SWDS may be inappropriate for developing countries with a high percentage of unmanaged
shallow sites, as it will probably lead to overestimation of emissions. Therefore, inventory agencies in developing countries areencouraged to use 0.4 as their MCF, unless they have documented data that indicates managed landfill practices in their country.
Source: Reference Manual of the IPCC Guidelines.

Deg r a da ble o r g a nic c a r b o n ( DO C)
Degradable organic carbon is the organic carbon that is accessible to biochemical decomposition, and should be
expressed as Gg C per Gg waste. It is based on the composition of waste and can be calculated from a weighted
average of the carbon content of various components of the waste stream. The following equation, as presented
in the IPCC Guidelines, estimates DOC using default carbon content values:
EQUATION 5.4
DOC = ( 0.4 • A ) + ( 0.17 • B ) + ( 0.15 • C ) + ( 0.3 • D )Where:A = Fraction of MSW that is paper and textiles
B = Fraction of MSW that is garden waste, park waste or other non-food organic putrescibles
C = Fraction of MSW that is food waste
D = Fraction of MSW that is wood or straw

The default carbon content values for these fractions can be found in the IPCC Guidelines (Table 6-3, Reference
Manual).3 The use of national values is encouraged if data are available. National values can be obtained by
performing waste generation studies and sampling of different SWDS within a country. If national values areused, survey data and sampling results should be reported. In addition, it is important that inventory agencies
exclude lignin from their DOC calculations if the default value (0.77) for DOCF is used, as discussed below.
F r a c t io n o f d e g r a da b le o r g a n ic c a r bo n di s s i mi la t ed ( DO C F )DOCF is an estimate of the fraction of carbon that is ultimately degraded and released from SWDS, and reflects
the fact that some organic carbon does not degrade, or degrades very slowly, when deposited in SWDS. The
IPCC Guidelines provide a default value of 0.77 for DOCF. Based on a review of recent literature, it appears that
this default value may be an overestimate. It should only be used if lignin C is excluded from the DOC value.
For example, experimental values in the order of 0.5-0.6 (including lignin C) have been used in the Netherlands(Oonk and Boom, 1995) and demonstrated to give reliable estimates of landfill gas generated and recovered in
the Netherlands. It is also good practice to use a value of 0.5-0.6 (including lignin C) as the default. National
values for DOCF or values from similar countries can be used for DOCF, but they should be based on welldocumented research.

3 From Bingemer and Crutzen (1987).

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.9

WasteChapter 5

F r a c t io n o f CH 4 i n la nd f il l g a s ( F)
Landfill gas consists mainly of CH4 and carbon dioxide (CO2). The CH4 fraction F is usually taken to be 0.5, but
can vary between 0.4 and 0.6, depending on several factors including waste composition (e.g. carbohydrate andcellulose). The concentration of CH4 in recovered landfill gas may be lower than the actual value because of
potential dilution by air, so F values estimated in this way will not necessarily be representative.
M ethane recov ery ( R)Methane recovery is the amount of CH4 generated at SWDS that is recovered and burned in a flare or energy
recovery device. CH4 recovered and subsequently vented should not be subtracted from gross emissions. The
default value for methane recovery is zero. This default should only be changed when references documenting
the amount of methane recovery are available. Recovered gas volumes should be reported as CH4 not as landfill
gas, as landfill gas contains only a fraction of CH44. Reporting based on metering of all gas recovered for energy
utilisation and flaring is consistent with good practice. The use of undocumented estimates of landfill gas
recovery potential is not appropriate, as such estimates tend to overestimate the amount of recovery.
O x ida t io n fa cto r (O X)
The oxidation factor (OX) reflects the amount of CH4 from SWDS that is oxidised in the soil or other material
covering the waste. If the oxidation factor is zero, no oxidation takes place, and if OX is 1 then 100% of CH4 isoxidised. Studies show that sanitary landfills tend to have higher oxidation results than unmanaged dump sites.
For example, the oxidation factor at sites covered with thick and well-aerated material may differ significantly
from sites with no cover or where large amounts of CH4 can escape through cracks in the cover.
The default oxidation factor in the IPCC Guidelines is zero. Results from field and laboratory give a wide range,
but values higher than 0.1 are probably too high for national inventories. Field and laboratory CH4 and CO2
emissions concentrations and fluxes measurements should not be used directly. In general, these field andlaboratory experiments determine CH4 oxidation from uniform and homogeneous soil layers. In reality, only afraction of the CH4 generated will diffuse through such a homogeneous layer. Another fraction will escapethrough cracks or via lateral diffusion without being oxidised. Therefore, results from field and laboratory
studies may lead to overestimations of oxidation in landfill cover soils.
Currently, most industrialised countries with well-managed SWDS use 0.1 for OX, which is a reasonableassumption based on available information. In developing countries with less elaborate management practices,
the average value is probably closer to zero. The use of the oxidation value of 0.1 is justified for well-managed
landfills, in other cases the use of an oxidation value different than zero should be clearly documented andreferenced.
It is important to remember that any CH4 that is recovered must be subtracted from the amount generated before
applying an oxidation factor.

5.1.1.3

C OMPLETENESS

Inventory agencies should make efforts to include emissions from non-MSW SWDS. These include industrial
waste sites and sludge disposal sites as well as construction and demolition waste sites. As with MSW, the DOC
must be assessed to evaluate the potential significance of the sub-source category. Industrial waste generation or
disposal data may be hard to obtain, because they may be confidential or not reported. Usually, the non-MSW
SWDS are less significant contributors to national CH4 emissions than MSW SWDS.
Closed SWDS should not be a completeness issue, because both the FOD and the default methods use yearly
waste disposal. Therefore, the waste that is present in a closed landfill should also have been accounted for.

5.1.1.4

D EVELOPING A CONSISTENT TIME SERIES

Given the differences in approach and expected results between the FOD and default methods, a time series
should be developed using the same method (i.e. methods should not be mixed). Thus, if an inventory agency
decides to move from the default to the FOD method, they need to recalculate the base year and the entire timeseries with the new approach. In this situation, inventory agencies will need to derive a time series of historicalwaste disposal data to support the FOD approach. The method of this derivation and number of years affectedmust be clearly described. To ensure consistency over time, it is good practice to recalculate emissions estimatesusing past and current methods to ensure that any trends in emissions are real and not caused by changes in the

4 CO emissions from landfill gas recovery combustion are of biogenic origin and should not be included in national totals.
2

5.10

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

estimation methodologies. These recalculations should be carried out according to the guidance in Chapter 7,
Methodological Choice and Recalculation, Section 7.3.2.2, Alternative Recalculation Techniques.
Given the significance of this source category in many national inventories, and the limitations of the default
method, inventory agencies should collect and maintain as much historical data as possible to enable futurerecalculations with more accurate methods. Inventory agencies should also take into account the timedependence of several parameters related to waste composition and landfill design.

5.1.1.5

U NCERTAINTY ASSESSMENT

Uncertainty estimates for MSWT and MSWF and the default model parameters are given in Table 5.2. The
estimates are based on expert judgement. If an inventory agency uses national values for these factors, it should
evaluate the uncertainty of these values consistent with the guidance provided in Chapter 6, Quantifying
Uncertainties in Practice.
Some uncertainty information is available on the methane generation potential (L0), which equals MCF • DOC •DOCF • F • 16 / 12, and appears as a factor in the equations for both the default and the FOD methods. In the
Netherlands, where high quality data are available, the uncertainty for CH4 generation per tonne of waste isestimated to be approximately ±15% (Oonk and Boom, 1995). In countries with similar quality data,
uncertainties in quantities of CH4 generation per tonne of waste are expected to be of the same order. For
countries with poor quality data on CH4 generation per tonne of waste, the associated uncertainties could be of
the order of ±50%. The basis for the uncertainty assessment should be well documented.
The data in Table 5.2, Estimates of Uncertainties Associated with the Default Parameters in the IPCC Default
and FOD Methods for CH4 emissions from SWDS, show that the overall uncertainty associated with estimating
CH4 emissions from SWDS is likely to be high, perhaps a factor of two, even when national data are wellcharacterised. National data should be used where possible. Chapter 6, Quantifying Uncertainties in Practice,provides advice on quantifying uncertainties in practice. It includes eliciting and using expert judgements whichin combination with empirical data can provide overall uncertainty estimates.

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.11

WasteChapter 5

TABLE 5.2
ESTIMATES OF UNCERTAINTIES ASSOCIATED WITH THE DEFAULT PARAMETERSa
IN THE IPCC DEFAULT AND FOD METHODS FOR CH4 EMISSIONS FROM SWDS
Uncertainty Range b

Parameter

Country-specific:
Total Municipal Solid Waste (MSWT) andFraction of MSW sent to SWDS (MSWF)>±10% (<–10%, >+10%. The absolute value of the uncertainty
range is greater than 10%.) for countries with high quality data
(e.g. weighing at all SWDS)
For countries with poor quality data: more than a factor of two.

Degradable Organic Carbon (DOC) = 0.21 (maximal
default value in the IPCC Guidelines)–50%, +20%

Fraction of Degradable Organic Carbon Dissimilated(DOCF) = 0.77

–30%, +0%

Methane Correction Factor (MCF)=1–10%, +0%

= 0.4–30%, +30%

= 0.6

–50%, +60%

Fraction of CH4 in Landfill Gas (F) = 0.5–0%, +20%

Methane Recovery (R)The uncertainty range will depend on how the amounts of CH4
recovered and flared or utilised are estimated, but theuncertainty is likely to be relatively small compared to otheruncertainties if metering is in place.

Oxidation Factor (OX)

Include OX in the uncertainty analysis if a value other thanzero has been used for OX itself. In this case the justification
for a non-zero value should include consideration of
uncertainties, as specified in Section 5.1.1.2, Choice ofEmission Factors and Activity Data.

Methane Generation Rate Constant (k) = 0.05

–40%, +300%a

The estimates are valid only for the default values given in the IPCC Guidelines or in the table, and are based on expert judgement.
If the evaluation of additional data on the parameters provides data for the revision of the default values, the uncertainty range should
also be changed. When country-specific values are used, they should be accompanied with appropriate uncertainty values.

bSource: Judgement by Expert Group (see Co-chairs, Editors and Experts; CH4 Emissions from Solid Waste Disposal).

5.1.2

Reporting and documentation

It is good practice to document and archive all information required to produce the national emissions inventory
estimates as outlined in Chapter 8, Quality Assurance and Quality Control, Section 8.10.1, Internal
Documentation and Archiving. Some examples of specific documentation and reporting relevant to this source
category are provided below.
•

If the FOD method is used, historical data and k values used should be documented.

•

The distribution of waste to managed and unmanaged sites for the purpose of MCF should also be
documented with supporting information.

•

If methane recovery is reported, an inventory of known recovery facilities is desirable. Flaring and energy
recovery should be documented separately from each other.

•

Changes in parameters from year to year should be clearly explained and referenced.

It is not practical to include all documentation in the national inventory report. However, the inventory should
include summaries of methods used and references to source data such that the reported emissions estimates aretransparent and steps in their calculation may be retraced.

5.12

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

5.1.3

Waste

Inventory quality assurance/quality control(QA/QC)

It is good practice to conduct quality control checks as outlined in Chapter 8, Quality Assurance and Quality
Control, Table 8.1, Tier 1 General Inventory Level QC Procedures, and an expert review of the emissions
estimates. Additional quality control checks as outlined in the Tier 2 procedures in Chapter 8 as well as quality
assurance procedures may also be applicable, particularly if higher tier methods are used to determine emissions
from this source category. Inventory agencies are encouraged to use higher tier QA/QC for key source categories
as identified in Chapter 7, Methodological Choice and Recalculation.
Furthermore, transparency can be improved by the provision of clear documentation and explanations of work
undertaken in the following areas:
E st i ma t e o f t he e mi s s io n s u si ng dif f e r e nt a p pro a c he s•

If the emissions are estimated with the FOD method, inventory agencies should also estimate them with the
IPCC default method. The results can be useful for cross-comparison with other countries. Inventory
agencies should record the results of such comparisons for internal documentation, and investigate any
discrepancies.

Rev i e w o f e mi s sio n f a c t o r s•Inventory agencies should cross-check country-specific values for estimation with the available IPCC
values. The intent of this comparison is to see whether the national parameters used are consideredreasonable relative to the IPCC default values, given similarities or differences between the national source
category and the emission sources represented by the default.

Rev i e w o f a c t iv it y da t a•Inventory agencies should compare country-specific data to IPCC default values for the following activity
level parameters: MSWT, MSWF, and DOC. They should determine whether the national parameters arereasonable and ensure that errors in calculations have not occurred. If the values are very different,
inventory agencies should characterise municipal solid waste separately from industrial solid waste.

•

Where survey and sampling data are used to compile national values for solid waste activity data, QC
procedures should include:(i)

Reviewing survey data collection methods, and checking the data to ensure they were collected andaggregated correctly. Inventory agencies should cross-check the data with previous years to ensure
the data are reasonable.

(ii)

Evaluating secondary data sources and referencing QA/QC activities associated with the secondary
data preparation. This is particularly important for solid waste data, since most of these data are
originally prepared for purposes other than greenhouse gas inventories.

Inv o lv e me nt o f i nd u st r y a n d g o v e r n me nt e xp e r t s in r e v iew•

Inventory agencies should provide the opportunity for experts to review input parameters. For example,
individuals with expertise in the country’s solid waste management practices should review thecharacteristics of the solid waste stream and its disposal. Other experts should review the methane correction
factors.

V e r if i c a t i o n o f e mi s s i o n s•Inventory agencies should compare national emission rates with those of similar countries that havecomparable demographic and economic attributes. This comparison should be made with countries whose
inventory agencies use the same landfill CH4 estimation method. Inventory agencies should study significant
discrepancies to determine if they represent errors in the calculation or actual differences.

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.13

WasteChapter 5

5.2

EMISSIONS FROM WASTEWATERHANDLING

Handling of domestic and industrial wastewater under anaerobic conditions produces CH4.5 The methodologicalissues concerning CH4 emissions from domestic and industrial wastewater handling systems are consideredseparately in this discussion because the types of activity data and emission factors needed for each sub-source
category are different. Both wastewater systems are discussed in Section 5.2.2, Reporting and Documentation,and Section 5.2.3, Inventory Quality Assurance/Quality Control (QA/QC).

5.2.1

Methodological issues

5.2.1.1

D OMESTI C WASTEWATERIn developed countries, most domestic wastewater is handled in aerobic treatment facilities and lagoons. In
developing countries, a small share of domestic wastewater is collected in sewer systems, with the remainder
ending up in pits or latrines.
Some industrial wastewater may be discharged into municipal sewer lines where it combines with domestic
wastewater.

CHOICE OF METHODThe IPCC Guidelines describe a single method for calculating CH4 emissions from domestic wastewater
handling. Emissions are a function of the amount of waste generated and an emission factor that characterises theextent to which this waste generates CH4. Any CH4 that is recovered and flared or used for energy should be
subtracted from total emissions. The simplified general equation is as follows:
EQUATION 5.5
Emissions = (Total Organic Waste • Emission Factor) – Methane Recovery

Depending on the available activity data and emission factors, this method can be applied at various levels of
disaggregation. The decision tree in Figure 5.2, Decision Tree for CH4 Emissions from Domestic Wastewater
Handling, describes how to determine the appropriate level of disaggregation in applying the IPCC method.
Regardless of the level of disaggregation, the steps in good practice in inventory preparation for CH4 fromwastewater are as follows:(i)

Characterise the wastewater systems in the country;(ii)

Select the most suitable parameters;(iii)

Apply the IPCC method.

5 Good practice methods for estimating indirect nitrous oxide (N O) emissions from sewage disposal were described with2

other indirect N2O sources in Chapter 4, Agriculture, Section 4.8, Indirect N2O Emissions from Nitrogen Used in Agriculture. Given the present state of data availability, the highly simplified method described in the IPCC Guidelines for direct N2Oemissions from wastewater disposal represents good practice as it stands. This is an area where future work is needed,
however, to make possible the level of detail in the corresponding parts of the Agriculture Sector.

5.14

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Figure 5.2

Waste

Decision Tree for CH4 Emissions from Domestic
Wastewater Handling

Determine the fraction of wastewaterfrom industrial sources discharged tocity sewers(See Figure 5.3, Wastewater Flows,
Treatment Systems, and Potential CH4Emissions)

List the sources ofwastewater entering
domestic wastewater
treatment facilities

Box 4
Is therea well-documented
national
method?

Estimate CH4
emissions fromdomestic wastewater
handling using
national method

Yes

No

Are
data available
for wastewater source
characterisation?

No

Ifwastewater
handling is a key
source category, is domestic
wastewater a significant
sub-source category?
(Note 1 andNote 2)

Box 1

No

Estimate CH4
emissions fromdomestic wastewater
handling using the‘check method’

Yes
Yes
Collect data or use
expert judgement tocharacterise
wastewater sourcesAre
country-specificparameters available
for the IPCC
method?

No

Yes
Box 3
Estimate
CH4 emissions fromdomestic wastewater
handling using the IPCC
method and countryspecific parameters

Box 2
Estimate
CH4 emissions fromdomestic wastewater
handling using the IPCC
method and default
parameters

Note 1: A key source category is one that is prioritised within the national inventory system because its estimate has a significant
influence on a country’s total inventory of direct greenhouse gases in terms of the absolute level of emissions, the trend in emissions, orboth. (See Chapter 7, Methodological Choice and Recalculation, Section 7.2, Determining National Key Source Categories.)
Note 2: As a rule of thumb, a sub-source category would be significant if it accounts for 25-30% of emissions from the source category.

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.15

WasteChapter 5

BOX 5.1
CHECK METHOD

Equation 5.6 presents a quick method to check national estimates. Default parameter values areincluded to enable a sample calculation to be made.
EQUATION 5.6
WM = P • D • SBF • EF • FTA • 365 • 10–12
Where:
WM = Annual CH4 emission per country, from domestic wastewater (Tg)
P = Population of country or urban population for some developing countries (person)
D = Organic load in biochemical oxygen demand per person (g BOD/person/day),overall default = 60 g BOD/person/day
SBF = Fraction of BOD that readily settles, default = 0.5
EF = Emission factor (g CH4/g BOD), default = 0.6
FTA = Fraction of BOD in sludge that degrades anaerobically, default = 0.8

Over 50% of the BOD in domestic wastewater is associated with non-dissolved solids, much ofwhich rapidly settle under a wide range of conditions. For example, a conventional settling tanktypically removes 33% of suspended solids, whereas a figure of 50% is more appropriate to many
longer-term processes such as lagoons, septic tanks, latrines, and ungraded sewers. This is SBF in
the equation above. Furthermore, it is believed that in many countries a very large fraction of thissettleable BOD will degrade anaerobically, resulting in the high FTA (0.8). The remaining
parameters are as defined in the IPCC Guidelines.
For countries that are extensively sewered, employ exclusively aerobic processes, and whose
sludge is treated by non-CH4 producing procedures or by anaerobic digestion with combustion ofCH4, the FTA would be significantly lower or zero. In these cases, the full IPCC Guidelines
method would be more accurate. For countries where data are unavailable to determine thepercentage of population connected to the various treatment types in use or, more particularly,
when there is a significant unsewered population, the full IPCC procedure can miss significant
emissions and its results should be reviewed with results from the check method.
This method can be used to make a rough estimate of global CH4 emissions from domestic
wastewater. Setting the global population P to 6 billion and EF to 0.6, one will arrive at total WM
of 32 Tg/yr. This is in the same range as the 29 Tg/yr global estimate in Doorn and Liles (1999).

CHOICE OF EMISSIO N FACTORSThe emission factor for each waste type is a function of the maximum methane producing potential of eachwaste type (Bo) and the weighted average of the methane conversion factors (MCFs) for the different wastewater
treatment systems used in the country, as shown in Equation 5.7. The MCF indicates the extent to which themethane producing potential (Bo) is realised in each type of treatment method.
EQUATION 5.7
Emission Factor = Bo • Weighted Average of MCFs
Where:
Bo = Maximum methane producing capacity (kg CH4/kg BOD or kg CH4/kg COD)
MCF = Methane conversion factor (fraction)

The derivation of each of these terms is described below.

5.16

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

M a xi mu m me t ha n e pro d u ci ng ca pa c it y ( B o )Good practice is to use country-specific data for Bo, expressed in terms of kg CH4/kg BOD removed to beconsistent with the activity data. If country-specific data are not available, a default value can be used. The IPCC
Guidelines suggest a default value of 0.25 kg CH4/kg COD (Chemical Oxygen Demand), based on a theoretical
calculation. Comprehensive field test data (Doorn et al., 1997)6 are in good agreement with the default value.
Note that degradable carbon in organic waste can be measured in terms of either BOD or COD. For typicaldomestic raw sewage, COD (mg/l) is 2 to 2.5 times higher than BOD (mg/l). Therefore, it is important to use
emission factors that are consistent with the measure of degradable carbon being used. The IPCC Guidelines
provide only one default value of Bo that has to be applied to both COD and BOD. This is not consistent with theobserved differences between BOD and COD levels in raw sewage. Given the differences in the amount of BOD
and COD in wastewater this can result in estimates of different emissions levels from the same amount ofwastewater depending on which measure is used. To ensure that the resulting emission estimate from a given
amount of wastewater is the same regardless of the measure of organic carbon is used, the COD-based value ofBo should be converted into a BOD-based value via up-scaling with a default factor of 2.5. Thus, it is goodpractice to use a default value of 0.25 kg CH4/kg COD or a default value of 0.6 kg CH4/kg BOD.
Weig ht e d a v e r a g e o f M CF s
The MCF is an estimate of the fraction of BOD or COD that will ultimately degrade anaerobically. The first stepin determining the weighted MCF is to characterise the wastewater treatment systems in the country by
producing a list of CH4 emission sources. Figure 5.3 below presents a comprehensive picture of the flow ofdomestic and industrial wastewater through various treatment options. Those treatment options shown in bold
are potential CH4 sources.
Figure 5.3

Wastewater Flows, Treatment Systems, and Potential
CH4 Emissions

Industrial/domestic wastewater

Collected

Uncollected

Untreated

TreatedSea,
River,
Lakes

Sewered to
Plant

Aerobic

SludgeAnaerobic
Digestion

Note:

Treated on site(latines, septic systems)
Stagnant
Sewer

UntreatedTogroundSea,
River,
Lakes

Anaerobic

Reactor

LagoonLand
Application

Italic text in a bold frame box indicates areas with the potential for CH4 emissions.

6 This reference indicated a representative value of 0.21 kg CH /kg COD.
4

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.17

WasteChapter 5

In the IPCC Guidelines, the weighted MCF value is determined according to Equation 5.8:
EQUATION 5.8
Weighted MCFi =∑x (WSix • MCFx)

Where:
WSix = Fraction of wastewater type i treated using wastewater handling system x
MCFx = Methane conversion factors of each wastewater handling system x

The IPCC Guidelines propose a separate calculation for wastewater and for sludge removed from thewastewater. The distinction is inappropriate for most countries, however, because sludge is rarely collected
separately. If sludge separation is practised and appropriate statistics are available, then these sub-source
categories should be separated. Such separation will not affect the overall estimate unless there are countryspecific Bo measurements for sludge and wastewater. Typically, the theoretical default Bo values for sludge andwastewater are the same. If default factors are being used, emissions from wastewater and sludge can be
estimated together. In this case, summing across i terms becomes unnecessary. Where a separate estimate foremissions from sewage sludge is not made, the weighted MCF for primary treatment and aerobic secondary
treatment may need to be greater than zero, reflecting the typical sludge processing routes for that country.
Regardless of how sludge is treated, it is important that CH4 emissions from biosolids (sludge) sent to landfills or
used in agriculture are not included in this sector.
As mentioned above, the wastewater characterisation will determine the fraction of each wastewater type treatedby a particular type of system. To determine the use of each type of treatment system, it is good practice to referto national statistics (e.g. from regulatory authorities). If these data are not available, wastewater associations orinternational organisations such as the World Health Organization (WHO) may have data on system usage.
Otherwise, consultation with sanitation experts can help and expert judgement can be applied (see Chapter 6,
Quantifying Uncertainties in Practice, for general guidance on eliciting expert judgement). Urbanisation statistics
may provide a useful tool (e.g. city sizes and income distribution), assuming that rural populations are less likely
to have access to wastewater treatment in most countries.
If no national data are available, then Equation 5.8 can be modified as follows to incorporate the expert
judgement of sanitation engineers and other experts:
EQUATION 5.9
Weighted MCF = Fraction of BOD that will ultimately degrade anaerobically

The determination of weighted MCF through expert judgement should be fully documented. Default data
provided by the IPCC Guidelines can be used as a basis for expert judgement.

CHOICE OF ACTIVITY DATA
The activity data for this source category is the amount of organic waste in a country. Total Organic Waste(TOW) is a function of human population and waste generation per person, and is expressed in terms ofbiochemical oxygen demand (kg BOD/year):
EQUATION 5.10
TOW = P • Ddom
Where:
TOW = Total organic waste (kg BOD/yr)
P = Human population (1000 persons)Ddom = Degradable organic component (kg BOD/1000 persons/yr)

As mentioned previously, the degradable carbon in organic waste can be measured either as BOD or COD, andthe COD-based value should be converted into a BOD-based value by multiplying by a default factor of 2.5. For

5.18

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

domestic wastewater, BOD data are more likely to be available. The IPCC Guidelines provide default values for
BOD for different regions in the world (see Table 6-5, Reference Manual of the IPCC Guidelines).
Total population statistics should be readily available from national statistics agencies or the United Nations. If
significant amounts of waste in rural areas is expected to degrade aerobically, as is the case in some developing
countries, then it is good practice to compute the estimate using only the urban population.

COMPLETENESS
The IPCC Guidelines present the main wastewater handling methods in developed and developing countries (seeTable 6-4, Reference Manual of the IPCC Guidelines). This table mentions sources such as latrines, riverdischarge, sewer lines and septic tanks, but the current method does not allow for their inclusion. (See Doorn andLiles, 1999 for information on emissions from these sources.) A diagram such as Figure 5.3, Wastewater Flows,
Treatment Systems, and Potential CH4 Emissions, may be more useful than Table 6-4, Reference Manual of the
IPCC Guidelines.

DEVELOPING A CONSISTENT TIME SERIESEmissions from domestic wastewater handling should be calculated using the same method and data sets forevery year in the time series. Where consistent data are unavailable for the same method for any years in the timeseries, these gaps should be recalculated according to the guidance provided in Chapter 7, Methodological
Choice and Recalculation, Section 7.3.2.2, Alternative Recalculation Techniques.

UNCERTAINTY ASSESSMENT
Table 5.3 presents uncertainty ranges assigned to the parameters discussed in the text above.
TABLE 5.3
DEFAULT UNCERTAINTY RANGES FOR DOMESTIC WASTEWATER
Parameter

Uncertainty Range

Human Population–5%, +5%

BOD/person–30%, +30%

Maximum Methane Producing Capacity(Bo)–30%, +30%

Fraction Treated Anaerobically

The uncertainty range should be determined by expert judgement, bearing
in mind that this is a fraction and uncertainties cannot take it outside therange 0 to 1.

Source: Judgement by Expert Group (see Co-chairs, Editors and Experts; CH4 and N2O Emissions from Wastewater Handling).

Chapter 6 provides advice on quantifying uncertainties in practice. It includes guidance on eliciting and using
expert judgements which in combination with empirical data can provide overall uncertainty estimates.

5.2.1.2

I NDUSTRIAL WASTEWATER

Industrial wastewater may be treated on site or released into domestic sewer systems. If it is released into thedomestic sewer system, the emissions should be covered there. Therefore, this discussion deals with estimating
CH4 emissions from on-site industrial wastewater treatment.

CHOICE OF METHOD
The method for calculating emissions from industrial wastewater in the IPCC Guidelines is similar to the oneused for domestic wastewater. The development of emission factors and activity data is more complex because
there are many types of wastewater, and many different industries to track.
The most accurate estimates of emissions for this source category are based on measured data from point
sources. Due to the high costs of measurements and the potentially large number of point sources, collecting
comprehensive measurement data is very difficult. Therefore, it is suggested that inventory agencies use a topdown modified IPCC Guidelines approach. The decision tree in Figure 5.4 defines good practice in adapting themethods in the IPCC Guidelines to these country-specific circumstances.

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.19

WasteChapter 5

CHOICE OF EMISSIO N FACTORS
There are significant differences in the CH4 emitting potential of different types of industrial wastewater. To theextent possible, data should be collected to determine the maximum methane producing capacity (Bo) and thefraction of waste treated anaerobically (weighted MCF) in each industry. Good practice is to use country- andindustry sector-specific data that may be available from government authorities, industrial organisations, orindustrial experts. Currently, however, most inventory agencies will find detailed industry sector-specific data
unavailable or incomplete. If no national data are available, it is good practice to use the IPCC COD-default
factor for Bo (0.25 kg CH4/kg COD).
In determining the fraction of waste treated anaerobically, expert judgement based on the advice of engineers
and other experts should be used. A peer-reviewed survey of industry wastewater treatment practices is one
useful technique for estimating these data. Surveys should be conducted frequently enough to account for major
trends in industry practices (i.e. 3-5 years). Chapter 6, Quantifying Uncertainties in Practice, Section 6.2.5,
Expert Judgement, describes how to elicit expert judgement for uncertainty ranges. Similar expert elicitation
protocols can be used to obtain the necessary information for other types of data if published data and statistics
are not available.
Figure 5.4

Decision Tree for CH4 Emissions from Industrial
Wastewater Handling

List industries that
produce large
volumes of organic
wastewater
Identify the top 3 or 4
industries with the largest
potential for wastewater
CH4 emissionsFor
the 3 or 4 mostimportant industries,
is it possible to collect or
estimate COD
data?
Yes
Estimate the share of COD
from the important
industries treated on-site(i.e. not discharged to city sewers)No

If
wastewater
handling is a key
source category, is industrial
wastewater a significant
sub-source category?
(Note 1 andNote 2)

Box 1

No

Estimate CH4
emissions for allindustries using
expert judgement
or default values
for COD data

Yes
Collect or estimate COD
for the 3 or 4 mostimportant industries

Box 2
Calculate CH4 emissions
from industrial
wastewater based on
COD from mostimportant industries
treated on-site
Note 1: A key source category is one that is prioritised within the national inventory system because its estimate has a significant
influence on a country’s total inventory of direct greenhouse gases in terms of the absolute level of emissions, the trend in emissions, orboth. (See Chapter 7, Methodological Choice and Recalculation, Section 7.2, Determining National Key Source Categories.)
Note 2: As a rule of thumb, a sub-source category would be significant if it accounts for 25-30% of emissions from the source category.

5.20

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

CHOICE OF ACTIVITY DATA
The first step in estimating the total industrial organic waste produced is to characterise by listing the industry
sectors in the country which produce large volumes of organic wastewater. Since a limited number of industries
are likely to produce most of the industrial wastewater (e.g. food processing, pulp and paper), it is good practice
to focus on these industrial sectors. National statistics, regulatory agencies, wastewater treatment associations orindustry associations can provide this information.
Next, the COD inputs for the top three or four identified major industrial sectors should be quantified. This may
require some expert judgement. In some countries, COD and total water usage per sector data may be available
directly from a regulatory agency. An alternative is to obtain data on industrial output and tonnes COD produced
per tonne of product from the literature. The IPCC Guidelines present typical COD values for some industries.
However, these values have been updated below (Table 5.4). Both sources are consistent with good practice,depending on national circumstances. For the remaining industries, an overall combined COD output should be
assigned. Production data can be obtained from national statistics.
A significant fraction of industrial wastewater may be discharged into municipal sewers to be treated or disposedof with domestic wastewater. This fraction will likely have to be estimated by expert judgement and should be
added to the domestic wastewater loading.

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.21

WasteChapter 5

TABLE 5.4
INDUSTRIAL WASTEWATER DATA
Industry Type

Wastewater
Wastewater
Generation Generation Range(m3/Mg)BOD

BOD Range

COD

COD Range

(g/l)

(g/l)

(g/l)

(g/l)

(m3/Mg)Animal Feed

NA

NA

NA

Alcohol Refining

24

16-32

NA

3-11

11

5-22

Beer & Malt

6.3

5.0-9.0

1.5

1-4

2.9

2-7

Coffee

NA

5.4

2-9

9

3-15

Coke

1.5

1.3-1.7

NA

0.1

0.1

Dairy Products

7

3-10

2.4

1-4

2.7

1.5-5.2

Drugs & Medicines

NA

0.9

5.1

1-10

Explosives

NA

NA

NA

Fish Processing

NA

8-18

1.5

2.5

Meat & Poultry

13

8-18

2.5

2-3

4.1

2-7

Organic Chemicals

67

0-400

1.1

1-2

3

0.8-5

Paints

NA

1-10

NA

NA

1-10

Petroleum Refineries

0.6

0.3-1.2

0.4

1-8

1.0

0.4-1.6

Plastics & Resins

0.6

0.3-1.2

1.4

1-2

3.7

0.8-5

Pulp & Paper (combined)

162

85-240

0.4

0.3-8

9

1-15

Soap & DetergentsNA

1.0-5.0NA

0.3-0.8NA

0.5-1.2

Soft Drinks

NA

2.0

NA

1.0

NA

2.0

Starch Production

9

4-18

2.0

1-25

10

1.5-42

Sugar Refining

NA

4-18

NA

2-8

3.2

1-6

Textiles (natural)172

100-1850.4

0.3-0.8

0.9

0.8-1.6

Vegetable Oils

3.1

1.0-5.0

0.5

0.3-0.8NA

0.5-1.2

Vegetables, Fruits & Juices

20

7-35

1.0

0.5-2

5.0

2-10

Wine & Vinegar

23

11-46

0.7

0.2-1.4

1.5

0.7-3.0

Notes: NA = Not Available.
When few data points are available, the range is assumed to be from –50 to +100%.
Source: Doorn et al. (1997).

COMPLETENESS
Industries may produce inventories that include emissions from on-site wastewater handling. It is good practiceto use these estimates provided they are transparent and otherwise consistent with the QA/QC principles set out
in Chapter 8, Quality Assurance and Quality Control. The national estimation method should be sufficiently
disaggregated to allow recognition of the separate accounting of these emissions and hence avoid double
counting.

DEVELOPING A CONSISTENT TIME SERIESEmissions from industrial wastewater handling should be calculated using the same method and data sets forevery year in the time series. Where consistent data are unavailable for the same method for any years in the timeseries, these gaps should be recalculated according to the guidance provided in Chapter 7, Methodological
Choice and Recalculation, Section 7.3.2.2, Alternative Recalculation Techniques.

5.22

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

UNCERTAINTY ASSESSMENT
The uncertainty ranges in Table 5.5 were assigned to the parameters discussed in the text above.
TABLE 5.5
DEFAULT UNCERTAINTY RANGES FOR INDUSTRIAL WASTEWATER
Parameter

Uncertainty Range

Industrial Production–25 %, +25%. Use expert judgement regarding the quality of data source toassign more accurate uncertainty range.

Wastewater/unit production

These data can be very uncertain as the same sector might use different
waste handling procedures in different countries. The product of theparameters should have less uncertainty. An uncertainty value can be
attributed directly to kg COD/tonne of product. –50 %, +100% is suggested(i.e. a factor of 2).

COD/unit wastewater

Maximum Methane Producing Capacity(Bo)–30%, +30%

Fraction Treated Anaerobically

The uncertainty range should be determined by expert judgement, bearing
in mind that this is a fraction and uncertainties cannot take it outside therange 0 to 1.

Source: Judgement by Expert Group (see Co-chairs, Editors and Experts; CH4 and N2O Emissions from Wastewater Handling).

5.2.2

Reporting and documentation

It is good practice to document and archive all information required to produce the national emissions inventory
estimates as outlined in Chapter 8, Quality Assurance and Quality Control, Section 8.10.1, Internal
Documentation and Archiving. Some examples of specific documentation and reporting relevant to this source
category are provided below.
The existing sectoral tables accompanied with a detailed inventory report provide good transparency for thissource category. The tables necessarily separate industrial from domestic wastewater treatment. The inventory
report should provide the remainder of the information on activity data, assumptions made and references, as
text. It is particularly important to document the use of default data in developing parameter values. Two
additional columns in the worksheet, one for comments and one for references (e.g. by number), should be
provided by the inventory agency.
It is not practical to include all documentation in the national inventory report. However, the inventory should
include summaries of methods used and references to source data such that the reported emissions estimates aretransparent and steps in their calculation may be retraced (such as changes in default values for MCFs).

5.2.3

Inventory quality assurance/quality control(QA/QC)

It is good practice to conduct quality control checks as outlined in Chapter 8, Quality Assurance and Quality
Control, Table 8.1, Tier 1 General Inventory Level QC Procedures, and an expert review of the emissions
estimates. Additional quality control checks as outlined in the Tier 2 procedures in Chapter 8 as well as quality
assurance procedures may also be applicable, particularly if higher tier methods are used to determine emissions
from this source category. Inventory agencies are encouraged to use higher tier QA/QC for key source categories
as identified in Chapter 7, Methodological Choice and Recalculation.
Furthermore, transparency can be improved by the provision of clear documentation and explanations of work
undertaken in the following areas:
Co mp a r i so n o f e mi s sio n s e st i ma t e us i ng d if f e r e nt a pp r o a c he s•

For domestic wastewater, inventory agencies should cross-check the national estimate, as appropriate, withemissions estimated using IPCC defaults or the ‘check method’. This cross-check should be a standard QC
practice wherever non-default parameters are used in the estimation method. Inventory agencies should
record the results of such comparisons for internal documentation, and investigate any unexplainablediscrepancies.

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.23

WasteChapter 5

Rev i e w o f e mi s sio n f a c t o r s•

For domestic wastewater, inventory agencies should compare country-specific values for Bo with the IPCC
default value (0.25 kg CH4/kg COD or 0.6 kg CH4/kg BOD). Although there are no IPCC default values forthe fraction of waste treated anaerobically, inventory agencies are encouraged to cross-check values for
MCFs against those from other countries with similar wastewater handling practices.

•

Inventory agencies should confirm the agreement between the units used for degradable carbon in the wastewith the units for Bo. Both parameters should be based on the same units (either BOD or COD) in order tocalculate emissions. This same consideration should be taken into account when comparing the emissions tothe check method or to another country’s emissions.

•

For industrial wastewater, inventory agencies should cross-check values for MCFs against those from othernational inventories with similar industrial wastewater characteristics.

Rev i e w o f a c t iv it y da t a•

For industrial wastewater, inventory agencies should review the secondary data sets (e.g. from national
statistics, regulatory agencies, wastewater treatment associations or industry associations) used to estimate
and rank industrial COD waste output. Some countries may have regulatory control over industrial
discharges, in which cases significant QA/QC protocols may already be in place for the development of thewastewater characteristics on an industry basis.

•

Inventory agencies should compare country-specific data (BOD in domestic wastewater or industry COD
output) to IPCC default values. If inventory agencies use country-specific values, they should document
why their country-specific or industry values differ from these default values.

Invo lve me nt of i n du st ry e x pert s in th e r eview•

In some countries, domestic wastewater treatment is highly scrutinised and regulated (especially in urban
areas) and as such, there may be opportunities for expert peer review of the inputs to the emissions
calculations. Peer review should involve experts that have knowledge of the particular input parameter.
Expert peer review is particularly important to verify MCF values and other parameters where IPCC
defaults are not available for cross-checks.

•

For industrial wastewater, inventory agencies should involve industry experts that have knowledge ofparticular input parameters. For example, industry experts should review the characteristics of the industrial
wastewater and its treatment with expertise in their specific industries. Expert peer review is particularly
important to verify MCF values and other parameters where IPCC defaults are not available for crosschecks.

5.24

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

5.3

EMISSIONS FROM WASTE
INCINERATION

5.3.1

Methodological issues

Incineration of waste produces emissions of CO2, CH4 and N2O. Emissions of CH4 are not likely to be significant
because of the combustion conditions in incinerators (e.g. high temperatures and long residence times).
Normally, emissions of CO2 from waste incineration are significantly greater than N2O emissions. Currently,
waste incineration is more common in developed countries, although it is common for both developed anddeveloping countries to incinerate clinical waste.
The methodology described here applies to incineration with and without energy recovery. Emissions from waste
incineration without energy recovery have to be reported in the Waste Sector, while emissions from incineration
with energy recovery should be reported in the Energy Sector.
Consistent with the IPCC Guidelines, only CO2 emissions resulting from the incineration of carbon in waste offossil origin (e.g. plastics, certain textiles, rubber, liquid solvents, and waste oil) should be included in emissions
estimates. The carbon fraction that is derived from biomass materials (e.g. paper, food waste, and woodenmaterial) is not included.

5.3.1.1

C HOICE OF METHOD

The choice of a good practice method will depend on national circumstances. The decision trees in Figures 5.5,
Decision Tree for CO2 Emissions from Waste Incineration, and 5.6, Decision Tree for N2O Emissions from
Waste Incineration, define good practice in adapting the methods in the IPCC Guidelines to these countryspecific circumstances. Figures 5.5 and 5.6 describe respectively the choice of method to estimate CO2 emissions
and N2O emissions.
The most accurate emissions estimates can be developed by determining the emissions for each type of waste(e.g. municipal solid waste (MSW), sewage sludge, clinical waste, and hazardous waste).
The methods for estimating CO2 and N2O from waste incineration differ because of the different factors that
influence emission levels. For this reason, they are discussed separately below.

Estimating CO 2 emissions
The IPCC Guidelines describe one method for estimating CO2 emissions from waste incineration. As shown inEquation 5.11, the activity data are the waste inputs into the incinerator, and the emission factor is based on the
carbon content of the waste that is of fossil origin only. The most accurate CO2 emissions estimates results fromdisaggregating the activity data into different waste types (e.g. municipal solid waste, sewage sludge, clinicalwaste, and hazardous waste). The burn out efficiency of combustion should also be included in the calculation.
EQUATION 5.11
CO2 emissions (Gg/yr) =∑i ( IWi • CCWi • FCFi • EFi • 44 / 12 )Where:
i = MSW: municipal solid waste
HW: hazardous waste
CW: clinical waste
SS: sewage sludge
IWi = Amount of incinerated waste of type i (Gg/yr)
CCWi = Fraction of carbon content in waste of type i
FCFi = Fraction of fossil carbon in waste of type i
EFi = Burn out efficiency of combustion of incinerators for waste of type i (fraction)
44 / 12 = Conversion from C to CO2

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.25

WasteChapter 5

Figure 5.5

Decision Tree for CO2 Emissions from Waste
Incineration

Is wasteincinerated in the
country?

No

Report‘Not Occurring’Box 1
Estimate CO2 emissions
using default carbon
content and fossil
fraction data

Yes

Are
waste
incineration data available
by waste type?
(e.g. MSW)No

Is this a
key source category?
(Note 1)

Assume all waste
is municipal solid
waste

Yes

Yes

Collect
activity data by
waste typeAre
country-specificanalyses of carbon
content
available?

No

Box 2
Estimate
CO2 emissions fromeach waste type using
default carbon content
and fossil fraction data

No

Yes
Box 3
Are
country-specificdata available for the fossil
carbon fraction of
the waste?

No

Estimate
CO2 emissions fromeach waste type using
country-specific carbon
content and default
fossil fraction data

Yes
Box 4
Estimate
CO2 emissions fromeach waste type using
country-specific carbon
content and fossil
fraction data

Note 1: A key source category is one that is prioritised within the national inventory system because its estimate has a significant
influence on a country’s total inventory of direct greenhouse gases in terms of the absolute level of emissions, the trend in emissions, orboth. (See Chapter 7, Methodological Choice and Recalculation, Section 7.2, Determining National Key Source Categories.)

5.26

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

Figure 5.6

Decision Tree for N2O Emissions from Waste
Incineration

Is wasteincinerated in the
country?

No

Report‘Not Occurring’Box 1
Estimate N2O emissions
using default emission
factors for municipal
solid waste

Yes

Are
waste incineration
activity data available
by waste type?
(e.g. MSW)No

Is this a
key source category?
(Note 1)

Assume all waste
is municipal solid
waste

Yes

Yes

Collect
activity data by
waste typeAre
measurement
data available foremissionfactors?

No

Box 4
Estimate
N2O emissions fromeach waste type using
measurement-based
emission factors

Yes

No
Box 3
Are
country-specificemission factors
available for
N2O?

Yes

Estimate
N2O emissions fromeach waste typeusing country-specificemission factors

No
Box 2
Estimate
N2O emissions fromeach waste type using
IPCC default
emission factors

Note 1: A key source category is one that is prioritised within the national inventory system because its estimate has a significant
influence on a country’s total inventory of direct greenhouse gases in terms of the absolute level of emissions, the trend in emissions, orboth. (See Chapter 7, Methodological Choice and Recalculation, Section 7.2, Determining National Key Source Categories.)

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.27

WasteChapter 5

The decision tree in Figure 5.5 can be used to estimate CO2 emissions for each incineration plant as well as for
estimating emissions from all plants. The best results will be obtained if emissions are determined for each plant,
and then summed.

Estimating N 2 O emissions
The calculation of N2O emissions is based on waste input to the incinerators and an emission factor:
EQUATION 5.12
N2O emissions (Gg/yr) =∑i ( IWi • EFi ) • 10–6

Where:
IWi = Amount of incinerated waste of type i (Gg/yr)
EFi = Aggregate N2O emission factor for waste type i (kg N2O/Gg)
Or
EQUATION 5.13
N2O emissions (Gg/yr) =∑i ( IWi • ECi • FGVi ) • 10–9

Where:
IWi = Amount of incinerated waste of type i (Gg/yr)
ECi = N2O emission concentration in flue gas from waste of type i (mg N2O/m3)
FGVi = Flue gas volume by amount of incinerated waste of type i (m3/Mg)
Figure 5.6 provides a general decision tree for the estimation of N2O emissions from waste incineration. The
decision tree can also be used for estimation of other gases (e.g. NOx). The best results will be obtained if N2Oemissions are determined for each plant based on the plant-specific monitoring data, and then summed.

5.3.1.2

C HOICE OF EMISSIO N FACTORS AND ACTIVI TY DATA

CO 2 emissions
CO2 is not normally directly monitored in exhaust gases. It can be calculated from the total carbon content of thewaste. This is commonly undertaken in most countries. CO2 emissions can also be estimated using default data
for the carbon content (see Table 5.6, Default Data for Estimation of CO2 Emissions from Waste Incineration).
However, where the carbon content of the waste is not known but the inventory agency has well-documented
measured data on CO2 emissions from waste incineration, these data can be used to obtain the country-specificcarbon content of the waste.
It can be difficult to differentiate between the biogenic and the fossil part of waste going for incineration. Data to
determine the fractions can be gathered from the waste analysis available in many countries. However, actual
data on the origin of waste is often lacking and may not be up to date.
The fractions of fossil and biogenic carbon are likely to change considerably in the future because of recent
waste legislation adopted in many countries (e.g. Japan, Norway, and the USA). The legislation will influence
the total waste flow incinerated as well as the fossil carbon content of the incinerated waste. It is uncertain how
new legislation will influence the fossil carbon content, and limited current data are available as the changes arestill occurring.
The fraction of fossil carbon will differ for different types of waste. The carbon in MSW and clinical waste is ofboth biogenic and fossil origin (default data are provided in Table 5.6). In sewage sludge the fossil carbon
usually can be neglected (only traces of detergents and other chemicals). The carbon in hazardous waste isusually of fossil origin (default data are provided in Table 5.6).
It is good practice to assume that the composition of incinerated MSW is the same as the composition of MSW
generated in the country. However, if a certain fraction of MSW is incinerated separately, the carbon content forthese streams must be determined specifically.

5.28

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

TABLE 5.6
DEFAULT DATA FOR ESTIMATION OF CO2 EMISSIONS FROM WASTE INCINERATIONC Content of Waste

MSW

Sewage Sludge

Clinical Waste

Hazardous Waste

33-50 % of waste (wet)10-40 % of sludge (drymatter)50-70 % of waste (drymatter) a

1-95 % of waste (wet)default: 30 %default: 60 %:0%30-50 %

90-100 % b

default: 40 %default: 90 %default: 40 %Fossil Carbon as %of Total Carbon

30-50 %
default: 40 %default: 50 %more information isneededEfficiency of
Combustion c

95 -99 %default: 95 %95 %50 -99.5 %95 –99.5 %default: 95 %default: 99.5 %aClinical waste contains mainly paper and plastics. The carbon content can be estimated from the following factors: C-content of paper:
50% and C-content of plastics: 75-85%.
b
The fossil carbon may be reduced if it includes carbon from packaging material and similar materials.
c
Depends on plant design, maintenance and age.
Source: Judgement by Expert Group (see Co-chairs, Editors and Experts; Emissions from Waste Incineration).

N 2 O emissions
Where practical, N2O emission factors should be derived from emission measurements. Continuous emission
monitoring is technically feasible, but not necessary for good practice. Periodic measurements should be
conducted sufficiently often to account for the variability of N2O generation (i.e. due to variable waste
composition), and different types of incinerator operating conditions (e.g. combustion temperature). Chapter 8,
Quality Assurance and Quality Control, Section 8.7.1.3, Direct Emission Measurements, provides further advice
on representativeness. Where measurement data are not available, other reliable means of developing emission
factors should be used (see Figure 5.6, Decision Tree for N2O Emissions from Waste Incineration).
Emission factors for N2O differ with facility type and type of waste. Emission factors for fluidised-bed plants arehigher than from plants with grate firing systems. Emission factors for MSW are lower than for sewage sludge.
Ranges of N2O emission factors reflect abatement techniques (the injection of ammonia or urea as used in someNOx abatement technologies may increase emissions of N2O), temperature, and the occupancy time of the waste
in the incinerator.
If site-specific N2O emission factors are not available, default factors can be used (see Table 5.7, Emission
Factors for N2O from Waste Incineration).
Many countries that use waste incineration should have plant-specific data for the amount of waste incinerated.
For hazardous waste and clinical waste, the activity data may be more difficult to obtain since waste incinerated
in some of these plants (e.g. on-site incinerators in chemical and pharmaceutical industry) may not be included inwaste statistics. For these waste types, plant-specific data may not be available, but overall data for total waste
incinerated may be available from waste regulators.
Categorisation of waste types varies across countries (e.g. in Japan sewage sludge is included in industrial waste)
as well as within countries (e.g. on a municipal or regional level). Therefore comparability of waste types may bedifficult. Where possible, waste should be categorised as above to facilitate consistency and comparability.

5.3.1.3

C OMPLETENESS

Completeness depends on the reporting of waste types and amounts burned. If the method is implemented at thefacility-level and then summed across facilities, it is good practice to ensure that all waste incineration plants areincluded. Inventory agencies should make efforts to report all waste types arising in their country.
It should be noted that there are possibilities of double counting CO2 emissions because waste is often
incinerated in facilities with energy recovery capabilities. Also, waste can be used as substitute fuel in industrial
plants other than waste incineration plants (e.g. in cement and brick kilns and blast furnaces). In order to avoid
double counting, the emissions from such processes should be reported under ‘other fuels’ in the Energy Sector,
not within the waste disposal source category.

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.29

WasteChapter 5

TABLE 5.7
EMISSION FACTORS FOR N2O FROM WASTE INCINERATION
Incineration
Plant TypeHearth or grate

MSW

Sewage Sludge

Clinical Waste

Hazardous Waste(from industry)kg N2O/Gg waste (dry)kg N2O/Gg sewage
sludge (dry matter)kg N2O/Gg waste(dry)

kg N2O/Gg waste(dry)

5.5-66 (Germany)

400 (Japan: wet)NANAaverage 5.5-11
highest value 30 (UK)40-150 (Japan: wet)
Rotating

NA

NA

NA

210-240 (Germany)

Fluidised bed

240-660 (Japan: wet)

800 (Germany)

NANA

100-1500 (UK)
300-1530 (Japan: wet)
Note: NA = Not Available.
Source:Germany: Johnke (1999),
United Kingdom: Environment Agency (1999),
Japan: Yasuda (1993).

5.3.1.4

D EVELOPING A CONSISTENT TIME SERIESEmissions from waste incineration should be calculated using the same method and data sets for every year in
the time series. Where consistent data are unavailable for the same method for any years in the time series, thesegaps should be recalculated according to the guidance provided in Chapter 7, Methodological Choice and
Recalculation, Section 7.3.2.2, Alternative Recalculation Techniques.

5.3.1.5

U NCERTAINTY ASSESSMENT

Tables 5.6 and 5.7 provide default ranges for CO2 and N2O emissions estimates, but inventory agencies should
assign country-specific uncertainties to the emission factors, especially if they used monitored data.
More recent information will have a lower uncertainty because it reflects changing practices, technicaldevelopments, or changing fractions (biogenic and fossil) of incinerated waste. In many developed countries,
uncertainties on the amount of incinerated waste are estimated around 5%, but the uncertainty could be higher
for some wastes, such as clinical waste.
The major uncertainty for CO2 is the estimation of the fossil carbon fraction. There is a high level of uncertainty
related to the separation of biogenic and fossil carbon fraction.
Direct measurement or monitoring of emissions of N2O has less uncertainty. For continuous and periodic
emission monitoring, uncertainty depends on the accuracy of measurement instruments. For periodic
measurement, uncertainty will also depend on the sampling frequency.
If default values for the N2O emission factors are used, uncertainty ranges have been estimated to be as high as
100%.
Chapter 6 provides advice on quantifying uncertainties in practice. It includes eliciting and using expert
judgements which in combination with empirical data can provide overall uncertainty estimates.

5.3.2

Reporting and documentation

It is good practice to document and archive all information required to produce the national emissions inventory
estimates as outlined in Chapter 8, Quality Assurance and Quality Control, Section 8.10.1, Internal
Documentation and Archiving. Some examples of specific documentation and reporting relevant to this source
category are provided below.

5.30

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Chapter 5

Waste

It is not practical to include all documentation in the national inventory report. However, the inventory should
include summaries of methods used and references to source data such that the reported emissions estimates aretransparent and steps in their calculation may be retraced.
Some countries use different categorisation schemes for waste at the local or regional level. In this case, theinventory agency should review consistency with the IPCC categorisation scheme and provide a rationale on
how it transformed the data to fit in the IPCC categories. Inventory agencies should clearly indicate the waste
types included in the waste estimates.
Inventory agencies should also include information on how they obtained the carbon content, the fossil carbon
fraction, and the N2O emission factors.
Many incineration plants produce electricity and heat. Combustion of waste for energy purposes should bereported under the Energy Sector of the IPCC Guidelines (CO2 from stationary combustion). Waste should bereported as ‘other fuel’ in the Energy Sector. These emissions should not be reported in the Waste Sector of the
IPCC Guidelines so as to avoid double counting.
Sometimes gas, oil, or other fuels are used as support fuel to start the incineration process or maintain thetemperature. Consumption of support fuel for this purpose should not be reported under waste incineration but
instead included in the Energy Sector. Support fuels normally account for less than 3% of total calorific input,
but they can be more important with the incineration of hazardous waste.

5.3.3

Inventory quality assurance/quality control(QA/QC)

It is good practice to conduct quality control checks as outlined in Chapter 8, Quality Assurance and Quality
Control, Table 8.1, Tier 1 General Inventory Level QC Procedures, and an expert review of the emissions
estimates. Additional quality control checks as outlined in the Tier 2 procedures in Chapter 8 and quality
assurance procedures may also be applicable, particularly if higher tier methods are used to determine emissions
from this source category. Inventory agencies are encouraged to use higher tier QA/QC for key source categories
as identified in Chapter 7, Methodological Choice and Recalculation.
Furthermore, transparency can be improved by the provision of clear documentation and explanations of work
undertaken in the following areas:
Rev i e w o f d ir e c t e mi s s io n me a s ur e me nt s•

Where direct measurement data are available, inventory agencies should confirm that internationallyrecognised standard methods were used for measurements. If the measurement practices fail this criterion,
then the use of these emissions data should be carefully evaluated.

•

Where emissions are measured directly, inventory agencies should compare plant-level factors among
plants, and also to IPCC defaults. They should review any significant difference between factors.

Rev i e w o f e mi s sio n f a c t o r s•Inventory agencies should compare country-specific or plant-specific values of the carbon content of waste,
the fossil carbon as fraction of total carbon, and the efficiency of combustion for the incinerator to thedefault values in Table 5.6.

•

Inventory agencies should review the QC procedures associated with the waste incineration data andanalysis used to develop site-specific emission factors. If there is insufficient QC, the uncertainty of thenational estimates should be assessed and the use of those data may need to be evaluated.

Invo lve me nt of e x pert s in th e peer rev iew•

Expert peer review should be directed at the characterisations of waste fuel and situations where default data
are not used. This is particularly true for hazardous and clinical waste, because these wastes are often not
quantified on a plant basis and can vary significantly from plant to plant.

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

5.31

WasteChapter 5

REFERENCESMETHANE EMISSIONS FROM SOLI D WASTE DISPOSAL SITES
Bingemer, H.G. and P.J. Crutzen (1987). ‘The production of methane from solid wastes.’ Journal of GeophysicalResearch, 92 (D2), pp. 2181-2187.
Intergovernmental Panel on Climate Change (IPCC) (1997). Revised 1996 IPCC Guidelines for National
Greenhouse Gas Inventories: Volume 3 Reference Manual. J.T. Houghton et al., IPCC/OECD/IEA, Paris,
France.
Oonk, H. and T. Boom (1995). Landfill gas formation, recovery and emissions, TNO-report R95-203, TNO,
Apeldoorn, The Netherlands.

EMISSIONS FROM WASTEWATER H ANDLI NG
Doorn, M.R.J., R. Strait, W. Barnard, and B. Eklund (1997). Estimate of Global Greenhouse Gas Emissions from
Industrial and Domestic Wastewater Treatment, Final Report, EPA-600/R-97-091, Prepared for UnitedStates Environmental Protection Agency, Research Triangle Park, NC, USA.
Doorn, M.R.J. and D. Liles (1999). Global Methane, Quantification of Methane Emissions and Discussion of
Nitrous Oxide, and Ammonia Emissions from Septic Tanks, Latrines, and Stagnant Open Sewers in theWorld. EPA-600/R-99-089, Prepared for U.S. EPA, Research Triangle Park, NC, USA.
Intergovernmental Panel on Climate Change (IPCC) (1997). Revised 1996 IPCC Guidelines for National
Greenhouse Gas Inventories: Volume 3 Reference Manual. J.T. Houghton et al., IPCC/OECD/IEA, Paris,
France.
Lexmond, M.J. and G. Zeeman (1995). Potential of controlled anaerobic wastewater treatment in order toreduce the global emissions of the greenhouse gases methane and carbon dioxide. Report No. 95-1,
Department of Environmental Technology, Agricultural University of Wageningen, P.O. Box 8129, 6700 EV
Wageningen, The Netherlands.

EMISSIONS FROM WASTE INCINERATION
Environment Agency of the United Kingdom (1999). Environment Agency's Technical Guidance Notes,
Environment Agency’s Pollution Inventory (1998 Data), UK.
Intergovernmental Panel on Climate Change (IPCC) (1997). Revised 1996 IPCC Guidelines for National
Greenhouse Gas Inventories: Volume 3 Reference Manual. J.T. Houghton et al., IPCC/OECD/IEA, Paris,
France.
Johnke, B. (1999). ‘Emissions from waste incineration’. Background paper for Expert meeting on good practicein inventory preparation : emissions from waste. IPCC/OECD/IEA National Greenhouse Gas Inventories
Programme, (Unpublished – TSU, Japan)
Yasuda, K. (1993). Emissions of Greenhouse Gases from Waste Incineration. Report of Kanagawa
Environmental Research Center, vol. 16, pp. 49-53, Kanagawa Environmental Research Center, Kanagawa,Japan.

5.32

IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories