Review Comments by Experts on Second Order Draft of Volume 5 of 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories
Comment ID Volume7998

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Comment

ExpertResponse

Authors noteThis chapter, unlike the previous ones, does not offer and does not cite methods ofmeasuring GHG from solid waste, either by fires that occur in open dumps; fires that canbe caused by third parties or autonomous by the presence of volatile substances that are
combusted with oxygen.

Alma Vargas

Noted

No action can be taken because comment is out of scope of 2019 Refinement.
In addition, Chapter 2 is dealing with waste data. Methodological issues foropen burning are covered under chapter 5.

Jean Bogner

Noted

No action can be taken because comment is out of scope of 2019 Refinement.

Pablo Aviles Hernández

Accepted withmodification

The part related to the use of country specific data and surverys are included in
the 2019 Refinement from the 2006 IPCC Guidelines in this section to clarify
that it was not deleted.

The section 2.3.2 was fully redrafted to clarifiy the TSS and VSS issues.. Also
table2.4A provided default value of treated and untreated sludge.

In countries like ours, the Dominican Republic, almost all solid waste landfills are openpit, and fires are very common, which produce a large smoke that lasts up to a week,
leaving a trail of pollution that not only affects the atmosphere, but also affects thepeople who reside in the neighboring cities and rural communities.
Considering the above, it is very pertinent that techniques are developed to measure thevolume and the dangerousness of these gases, in order to sensitize local governments thatthey must focus on establishing sanitary landfills in their territories and to classify thewaste before disposal final to avoid further contamination of the environment.
Obviously, awareness must reach households, companies and institutions, which is wherewaste is generated
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end

Please see two uploaded files which should be consulted together:

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101 UPDATING FROM 2006 IPCC GUIDELINES.
Country-specific data
It is desirable that each country use specific data about its territory on the generation,
composition and management practices of the DSM as a basis for the estimation of its
emissions. Therefore, as part of the implementation of good practices, efforts should bemade to promote the generation of official waste statistics in the countries, as well as theuse of standardized activities in the collection of sampling data in the SEDS.
Preferably, country-specific data should be obtained for the generation, composition andmanagement practices of the DSMs from official statistics on waste generated bynational statistical agencies, municipalities or other relevant government agencies, as well
as by elaborate surveys by companies or waste management organizations, among
others; or in its absence, through research projects (World Bank, OECD, IDB, JICA,
U.S. EPA, IIASA, EEA, etc.).
Large countries, with marked differences in the generation and treatment of waste fromone region to another, are recommended to use data from those regions, as far as
possible. See Chapter 2, Methods for Data Collection, of Volume 1, for more guidanceon general data collection and waste surveys.

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134

In the text (as in lines 146 to 147) you added information on VSS (and TSS), and type ofsludge (raw/stabilized). But in table 2.4 A there is no link with this information although
it is said that "it is good practice to differentiate […]". So I don't really understand what
for this information on TSS and VSS is provided. If it is for referencing purpose of the
DOC values, it could be more transparent just to add the information as a note in thetable 2.4A.
Moreover, if it is good practice to differentiate between raw and stabilized sludge,
UNFCCC reviews will expect annex 1 countries to do it. Please could you provide
separate defaults values for carbon content, nitrogen content and DOC ?

Céline Gueguen

Accepted

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128

It is indicated in the text that it is "good practice to split between "BIODEGRABLE"
and "FOSSIL" shares…". Do you mean between "biogenic" and " fossil" ? I guess yes(for CO2 emissions purpose), so it will be more transparent and consistent with the otherpart of the GL to use this wording “biogenic”.

Céline Gueguen

Accepted withmodification

The sentence has been deleted as it may cause confusion.

Comment ID Volume

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ExpertResponse

Muhammad Mohsin Iqbal

Accepted

Table 2.1 in FOD also contained data for Melanesia, Micronesia and Polynesia. They are
now missing from the SOD.

Mingming Wang

Accepted withmodification

SOD contains the available information on waste generation rates for Fiji,
Solomon Islands, Vanuatu (Melanesia) and Tonga (Polynesia) that is the same
as for FOD. Data were neither added nor deleted for mentioned regions in the
SOD.

In Table 2.3, the % of all composition categories for each region add up to 101% or99%, not 100%. Please rectify.

Mingming Wang

Noted

Footnote number 2 below the table explains the reasons for such descrepancy.

140

For Same reason in comment for Table 2.1, I will recommand to delete Table 2.3 andregional (mean) value in Annex 2A.2.

Masato Yamada

Rejected

Regional values are included so that they can be used for countries which do
not have data. Therefore, this table cannot be deleted.

139

140

Table 2.3: Region Western Europe: This table has been updated. The total of all waste
types including "others" now amounts to 100%. The waste type "others" still is very high(29,1%). For this type the content of organic carbon content can not be determined.
It would be helpful, if the waste types in table 2.3 correspond to the waste types in Line122 (especially "nappies" and "garden (yard) and park waste" are missing in table 2.3

Christoph Lampert

Accepted

Available data for nappies and garden and park waste was included in table 2.3.
Also, guidance has been added in the text on how to handle nappies and garden
and park waste.

2

150

151

To be consistent with Table 2.4A, this sentense should be "Sewage, food industry, paperindustry, textile industry and chemical industry will generate organic sludge".

Masato Yamada

Accepted

The section 2.3.2 was fully redrafted

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Muhammad Mohsin Iqbal

Accepted

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162

What is "WWT" sludge?

Masato Yamada

Accepted withmodification

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162

The use of uncertainty in percent makes this table abiguous. What does the percent of
uncertainty refer to (percent of dry matter as shown in the caption, or percent of theresulting carbon content)?

Andrea Tilche

Accepted

These are percents of uncertainty of the value in preceding column. Column
headings were updated.

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The sentence 'Information C and N content... waste water and agriculture', is not clear.
May please be clarified.

Muhammad Mohsin Iqbal

Accepted

The section 2.3.2 was fully redrafted .

181

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'In wet basis' is suggested to be written as 'on wet basis'

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'were added' is suggested to be changed to 'was added'

Authors note
Sentence has been changed

The section 2.3.2 was fully redrafted.
The word has been changed to "wastewater"This entire section is poorly written and needs to be reworded.

Andrea Tilche

Accepted

The section 2.3.2 was fully redrafted

In Annex 2A.1, for countries with empty cells, does it mean data not available or not
applicable (none-existent)? And if country level data is not available, is the default
approach to use regional data? Please clarify.

Mingming Wang

Accepted

A footnote has been added under the table to clarify that blank cells means thatno data is available and that regional data can be used in such cases.

188

Table 2A1. Isn't this table a little inconsistent with the Table 2.1? For example Southern
Asia moved from 0.21 to 0.5 t/cap/year but when I look at the countires the only one thathas a value larger than 0.5 is Maledives (0.91) so how come that the suggested default
for the region is 0.5?

Zbigniew Klimont

Accepted withmodification

The authors are very thankful for such detailed analysis of tables 2A.1 and 2.1,
eg. for region of Southern Asia. In SOD, the value for Sri Lanka is missing.
Taking into account that the MSW generation per capita for Sri Lanka is equal
to 1.86 t/cap/year the average MSW generation for Southern Asia region isequal to 0.50 t/cap/year. The data for Sri Lanka is added to the table.

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189

In order to increase the transparency of annex 2A2, please add a table including the titleof column at the beginning of each column.

Céline Gueguen

Accepted

Corrected as suggested

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189

Table 2A2 : Please consider that, for many countries, the default value for the category"other" is very high.
Considering the list of of waste (ligne 122), this category is supposed to include "(2)garden waste", "(6) nappies" and "(11) other (e.g. ash, dirt, dust, soil, electronic waste).
So, this category covers type of wastes very different in terms of DOC, carbon content(FC) and fossil carbon content (FCF) (see 2006 GL, vol 5, Chap 2, table 2.4) andtherefore in terms of CH4 emission .
There is a riskq that countries make a link between the "other" category in thecomposition table (2A2) and the "other, inert waste" category in table of default values
proposed in the the2006 GL . This would result in an underestimation of emissions.

Céline Gueguen

Accepted

We consider disaggregate Other to nappies and garden waste to be more in linewith Waste model. Available data for nappies and garden and park waste wasincluded in table 2.3. Also, guidance has been added in the text on how tohandle nappies and garden and park waste.

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Waste composition provided for France is supposed to come from Dong Qing Zhang etal. (2010) "Municipal solid waste management in China: Status, problems andchallenges". This document does not include any waste composition for France. Pleasecheck the references.

Céline Gueguen

Accepted withmodification

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replace "imagery" by "spatial" in "higher imagery resolution"

Brice Mora

Noted

The data for France used are from the 2018 NIR.

SOD Volume 5 Chapter 2 from lime 191-395 are references section. Comment
is not in line with text in Chapter 2. It may belong to other Volume or other
Volume.

Comment ID Volume

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ExpertResponse

Authors note

Brice Mora

Noted

SOD Volume 5 Chapter 2 from lime 191-395 are references section. This
comment is not in line with text in Chapter 2. It may belong to other Volume
or other Volume.

Table 2,1 - note 2 : "the per capita values should be multiplied with the population
WHOSE WASTE IS COLLECTED […] this encompasses ONLY urban population." In
the view of an inventory compiler for waste, capacity building to non annex 1 countries,
this is not complete: rural population is also generating waste (maybe with anothergeneration rate than urban one). These waste, even when not collected, are in some cases
discharges in collective dumps out of the villages where anaerobic decomposition
definitely occurs. These emissions must be considered in the inventory to ensurecompleteness. Otherwise there is an underestimation.
Therefore, in this view, the production ratio has to be multiplied with the TOTAL
national population AND, the fact that a part of rural waste may not be disposed in
dump/landfills could be considered using the parameter " fraction of MSW disposed to
SWDS" (and therefore has to reflect that a part of national waste is not collected) OR
could be considered using an additional national parameter "fraction of waste collected").

Céline Gueguen

Accepted withmodification

The paragraph above table 2.1 and footnotes under tables 2.1 and 2 A.1 havebeen modified to clarify that for developing countries using regional waste
generation rates provided in the updated Table 2.1 and for developing countries
in italics in the Table 2 A.1, the generation rates should be multiplied by theurban population only to obtain the total waste generated in the country. The
publication where data for most developing coutries are obtained "Hoornweg,
D., and Bhada-Tata P. (2012). What a Waste: A Global Review of Solid Waste
Management, Urban Development and Local Government Unit of the
Sustainable, The World Bank, 116 pp.Development Network" explains in themethodology that the waste generation rates per capita are estimated based on
total MSW generated in the country divided by the urban population. The total
waste generated in the country includes all types and sources subjects of waste.

62

Do the proposed default generation rates correspond to waste generated by the national
population only ? What about very touristic areas/countries (islands especially) where afraction of waste is generated by tourists ? Not considering tourists in the estimation of
the amount of waste disposed in landfills may lead to an underestimation.

Céline Gueguen

Noted

The waste generation rates per capita, especially for developing countries, weretaken from the publication "Hoornweg, D., and Bhada-Tata P. (2012). What a
Waste: A Global Review of Solid Waste Management, Urban Development andLocal Government Unit of the Sustainable, The World Bank, 116
pp.Development Network". The report explains in the methodology that thewaste generation rates per capita are estimated based on total MSW generated
in the country divided by the urban population. The total waste generated in the
country includes all types and sources/subjects of waste, including fromtourists. This is clear in the island- tourist countries such as Tonga, Fiji, etc. intable 2A.1.

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80

These two parameters are subject to change over time.....values provided in Tables 2.A.1
and 2A.2 can be used. This part does not cover details of the factors that influencemunicipal domestic waste. I'd reocmmend reading Alexis M.and James R's "Sustainable
recycling of municipal solid waste in developing countries".

Xiangzheng Deng

Accepted

The authors agree with the comment from the reviewer. This is why different
values for waste generation rates are provided in Table 2 A.1 so that thecompliers can construct proper time series which takes change in generation
rate over time. For waste composition, the available data from reference
between the period 2005 and 2018 were used to obtain representative values forthis period as data on composition for different periods are not available.
Moreover, the waste composition does not change as rapid as the waste
generation rates.

2

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69

Explain the term FOD as First Order Decay

Andrea Tilche

Acceptedrevised as suggested

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74

Change "are also" to "also"

Andrea Tilche

Accepted"are" have been removed

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189

The methodology defines a range of different MSW management options, of which theunspecified also covers recycling (at least for some countries), and for some countries
this fraction covers 60% or more. Given that this category may cover situations with bothvery low emissions (recycling) or relatively high, it is highly problematic to have a large
proportion of unspecified. Also there should be a special category for recycled waste.

Andrea Tilche

Noted

Although the authors acknowledge the issue raised by the reviewer,
unfortunately, data is not available to provide a specific category for recycling
or treatment technologies other than those included in the table. If a country has
the split of unspecified e.g. recycling, then the country may use the percentage
of such treatment technolgy and subtract from the total of unspecified as per theguidance provided under section 2.2.1 in the 2006 IPCC Guidelines for country
specific data (this part is copied back in the 2019 Refinement).

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98

In some countries, waste generated by tourists could be a substantial part of the total
waste generation. It is not clear if/how this is taken into account.

Ole-Kenneth Nielsen

Noted

The waste generation rates per capita, especially for developing countries, weretaken from the publication "Hoornweg, D., and Bhada-Tata P. (2012). What a
Waste: A Global Review of Solid Waste Management, Urban Development andLocal Government Unit of the Sustainable, The World Bank, 116
pp.Development Network". The report explains in the methodology that thewaste generation rates per capita are estimated based on total MSW generated
in the country divided by the urban population. The total waste generated in the
country includes all types and sources/subjects of waste, including fromtourists. This is clear in the island- tourist countries such as Tonga, Fiji, etc. intable 2A.1.

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234

replace "might introduce" by "may introduce".

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Comment ID Volume

ExpertResponse

Authors note

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It is said that for developing countries the data provided shall be multiplied with theurban population. Does this mean that it can be assumed that the rural population indeveloping countries does not produce any waste?

Comment

Christoph Lampert

Accepted

The paragraph and footnotes under tables 2.1 and 2 A.1 have been modified toclarify that for developing countries using regional waste generation rates
provided in the updated Table 2.1 and for developing countries in italics in the
Table 2 A.1, the generation rates should be multiplied by the urban population
only to obtain the total waste generated in the country since these rates assume
that the waste is generated by urban population only and not rural population.

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100

For Table 2.1, rates in the table seems to arithmetical means of rates for each countries
included in a certain region in Annex 2A.1. There are two problems for these
representative values. First is that the simple arithmetical mean of rates is not adequate
for this purpose because denominators of each rate are different. The representative value
should be calculated as the sum of numerators over the sum of denominators (both areamount of waste) for all countries included in a certain region. Secondaly, countries in acertain region may be in similer social and climate conditions. However, their are indiverse economical level. The MSW generation rates, component of MSW andintroduced waste management technologies is strongly affected to economy in a country.
Then, the mean rate of a certain region is not adquate to use for a specific rate for acertain country. I think country specific values in Annex 2A.1 is enough to show default
value in this guidline. So I will recommand to delete Table 2.1 and regional (mean) value
in Annex 2A.1.

Masato Yamada

Noted

The purpose of updating the regional values in Table 2.1 (which was also usedin 2006 IPCC Guidelines) is to provide default values for countries which do
not have data. Therefore, the table will not be deleted. The idea of using thearithmatic mean is to provide an average for the generation rates in countries insimilar regions which can be a good proxy for countries which don't have data.
Therefore, estimating the average generation rate based on the total waste
divided by the total population of the region will still have uncertainties. In
many cases, the raw data is not availble and therefore, the simple arithmaticmean was used.

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100

Please show the mean of "-" in the table.

Masato Yamada

Noted

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Table 2.1. I am surprised to see that there is no numbers waste management for Southern
Asia where India is central. To my knowledge there are several reports from thegovernment, regional offices, and also research papers reporting/estimating waste
generation for urban and rural population including estimates of collection efficiency,
open duming and also burning or waste. Also the generation rate for MSW of 500
kg/cap/year seems to be rather high compred to often quoted rates of about 0.5
kg/cap/day (urban) and about 0.3 (rural) which woudl give even less than half of that; infact probably about .16 ton/cap/year. As a matter of fact I suggest checking if thenumbers in the column with MSW Generation are not in fact in kg/cap/day (?).

Zbigniew Klimont

Accepted withmodification

The reference used for waste treatment practices in table 2.1 does not include
data for India or other countries in Southern Asia. Therefore, no data wasincluded for these countries. The reviewer did not provide any references tosource data from. The value 0.5 t/cap/year is typical for this region and may be
used for GHG emission estimation as a regional default value as well. In casecounrty-specific data is available, it is good practice to use such data. Guidanceon country specific data was added in section 2.2.1.

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Table 3.0 provides DOCf for different types of waste and also for bulk waste. It is
unclear if a country/city should use the specific DOCf for different types of waste (basedon the default fraction provided in Volume 5.2), or use the value for bulk waste because
different types waste are not collected separately in some nations or areas. Please clarify.

Mingming Wang

Noted

It is recommended that the country should use specifc DOCf value for eachwaste category if waste composition are available to them. DOCf value for bulk
waste should be used only when waste composition is not available. There is afootnote in Table 3.0 suggesting that bulk waste is used when waste
composition is not known.

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392

Overall the text, though improved from the FOD, still needs thorough editting to improvereadability - e.g Box 3.0A and 3.0B need substantial work

Fabiano Ximenes

Accepted withmodification

Box 3.0A and 3.0 B are revised particulry with Box 3.0B. In Box 3.0 B, theinformation exerpted from the literatures regarding the evidence of DOC
leacing from SWDS containing wet wastes during high rainfall events isprovided. The latter part describing the DOC calculation procedure is removed
as the box intends to provide information only.

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104

Recommend replacing "pipes and certain the number of gas exhausting (ventilation)
pipes" with "pipes and gas exhausting (ventilation) pipes"

Jeffrey Coburn

Accepted"-" is delete from table to be consistent across the chapter.

Corrected as suggested.

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107

Recommend replacing "of sunk of drainage pipe" with "of sunken drainage pipes"

Jeffrey Coburn

Accepted

Corrected as suggested.

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109

Jeffrey Coburn

Accepted

Corrected as suggested.

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131

Recommend replacing "In the case of drainage sunk, " with "In the case of sunken
drainage pipes, ""Less decomposable wastes were wood components including tree branches and leaves(Eleazer et al., 1997) harvested wood products such as sawn and engineered woodmaterials. "This reference is from a book published in 1997, and I suggest to replace itwith some literatures published after 2006.

Xiangzheng Deng

Accepted

More updated references are used for less decomposable waste (Wang et al.
2011, Wang and Balaz 2016, Ximines et al, 2018).

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131

Fabiano Ximenes

Accepted

More updated references are used for less decomposable waste (Wang et al.
2011, Wang and Balaz 2016, Ximines et al, 2018).

Would be better to quote more recent studies that have included a wide range of
harvested wood products - Eleazer's paper did not have that focus. Alternative text
suggested: "Less decomposable waste include harvested wood products such as sawn andengineered wood materials (e.g. Wang et al 2011).

Comment ID Volume

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135

This sentence may read better as follows: "Structural organization of the organic matterin the waste materials, particularly the lignin-like residual fraction present, was found tobe the predominant factor affecting their biodegradability (Bayard et al., 2017)."

Jeffrey Coburn

Accepted

Corrected as suggested.

Authors note

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Suggested alternative text: "The biodegradation yield of the waste components underanaerobic condition varies greatly depending on the material type, ranging from minimal
yield for wood and wood products (e.g Wang et al 2011) to high percentage (60-80%)
for food wastes and office paper (Eleazer et al 1997; Wang et al 2015).

Fabiano Ximenes

Accepted

Corrected as suggested.

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138

Suggest this alternative text: "Meanwhile, biogenic carbon conversion of paper products
varies greatly (21 to 96% - REF) depending on the type of paper".

Fabiano Ximenes

Accepted

Corrected as suggested.

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140

Suggest deleting "Meanwhile the diaper exhibited limited biodegradability (Wang et al.,2015)" - out of context and already included in the range above, no need to single it out.

Fabiano Ximenes

Accepted

Deleted as suggested.

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145

Please rewrite - I made the suggestion to include the text, but not in this way - in order tobe have a better flow from the previous sentences which talked about findings from lab
based experiments please change to: "From landfill excavation studies, carbon loss forwood was found to be low and climate did not influence much on decay of wood in
landfills - the observed higher levels of decay for some wood samples were attributed todifferences in wood species rather than climate (Ximenes et al., 2015)."

Fabiano Ximenes

Accepted

Corrected as suggested.

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152

The recommended DOCf values are not yet included in the IPCC waste spreadsheet
model. I assume this will happen in the final draft.

Hans Oonk

Accepted

The proposed DOCf values has integrated in the spreadsheet.

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152

Type of waste - first description would be more accurate if it stated instead "lessdecomposable wastes e.g. wood, engineered wood products and tree branches". Also
please correct the spelling for "Ximenes et al 2018".

Fabiano Ximenes

Accepted

Corrected as suggested.

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174

This section introduces the accournting of DOC leaching as something to account forwhen estimating emissions from degradable organic carbon in SWDS. However, there isno concerns that the degradability of the leaching DOC could be different from that of
the remaining DOC. Such differences in degradability are highly likely and should be
accounted for.

Andrea Tilche

Accepted withmodification

All DOC originally presented in solid waste should be accounted for inestimation of emission. Whenever the DOC lost with the leachate can bequantified and not considered in the estimation of emission in solid waste
category, the emission arising during leachate treatment should be estimated.
The degradability of DOC in leachate is likely to be different from theremaining DOC but accounted for in wastewater treatment and discharge

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154

"However, DOC leached from the SWDS was reported to be significant under extremely
wet condition" - Reference required

Fabiano Ximenes

Accepted withmodification

The references in which high rainfall intensity and high percentages of foodwaste reported to yield significant carbon lost from SWDS are provided in Box
3.0B.

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174

The introduction of lines 153-157 allow to skip Box 3.0B. The relevance of the DOC
leaching is still based only on 1 literature (Zahn et al (2017)). Furthermore, several
undefinded terms are used like "extremely wet conditions" of "high percentage of foodwaste". Furthermore, the sentence in line 160 and 162 is contradictory: "Recent literaturereported that the operation of anaerobic landfills under wet conditions yielded higherorganic carbon release in gas and leachate forms while reducing landfill gas production
potential due to carbon washout by leachate (Jiang et al., 2007)." In the first part of thesentence higher organic carbon releases in gas are mentioned, in the second part a
reduced landfill gas production is mentioned.

Christoph Lampert

Accepted withmodification

The evidences of siginificant DOC leaching were reported in high rainfall
intensity (Karanjekar et al., 2015) and high percentages of food wastes (Zhan etal., 2017) conditions. The extremely wet conditions refer to these reported
conditions. The first sentence between line 160-162 is also revised mentioning
high organic carbon in leachate yield lower gas production from SWDS.

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3 categories of SWDS have been added in the table. The "poorly managed semiaerobically SWDS" is defined with very detailled managing conditions. These conditions
may be known at the level of one site but could not be estimated at the national level.
Even if a questionnaire is sent to the SWDS (for those which are not closed yet) the
fraction ofd waste disposed in such condition may evolved from one year to another.
Do you have examples of countries, having such a precise and exhaustive historical
dataset of managing parameters of its landfills ?
...so, the criteria defining if a site is "poorly managed" is too "micro" (level of a site) andshould be more "macro" to become really applicable by inventory compilers.

Céline Gueguen

Accepted withmodification

Clear definition on criteria for well-managed active aeration has been given in
Table 3.1, as well as responding to comments No.4796.

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192

Verify bibliographic citation format of table 3.1

Poot-Delgado Carlos
Antonio

Accepted

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222

Verify bibliographic citation format

Poot-Delgado Carlos
Antonio

Accepted withmodification

Corrected as suggested.
Information have been mentioned to reflect the same references from table 3.0(New).

Comment ID Volume

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ExpertResponse

Authors note

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365

This is the only place where changes in the methane oxidation is mentioned as nessesary
to consider. However, no guidance on how to consider this parameter is provided, andnot mentioning of passive aerobation (i.e. biocover) is included in the revised guidelines!

Ole-Kenneth Nielsen

Rejected

Information in Appendix does not give the specific guidance of emission
estimation. This part provides technical materials where emission is poorly
understood or where there is insufficient information available. See the detail in
Chapter 1.3, Volume 1 in original 2006 IPCC Guidelines.

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376

Change "...and representative data is obtained." to "…and representative data are
obtained."

Jeffrey Coburn

Accepted

Corrected as suggested.

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49

Change "complier" to "compiler"

Jeffrey Coburn

Accepted

Corrected as suggested.

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49

50

This sentence implies that the document is about active aeration data, when that is only aminor component of the overall document. Should it say instead: "This refinementattempts to guide the inventory complier on estimation of CH4 emissions from SWDS
sites to the extent of current knowledge and data available"

Fabiano Ximenes

Accepted

Corrected as suggested.

780

5

3

50

50

Change "current knowledge and data available" to "current knowledge and available
data" for proper parallel structure of clauses

Jeffrey Coburn

Accepted

Corrected as suggested.

4644

5

3

57

58

In this sentence: "the fraction of the degradable organic carbon that decomposes underanaerobic conditions (DOCf)", "under anaerobic conditions" should be deleted

Ole-Kenneth Nielsen

Accepted

Corrected as suggested.

4808

5

3

60

60

"The parameter that is related to aerobic condition is expressed in terms of MCF." Thissentence is unclear - need to explicity define what MCF is here.

Fabiano Ximenes

RejectedDefinition on MCF is given in orginal text in 2006 Guideline

3418

5

3

62

63

In this sentence 'many countries'countries is in contradiction with the part in between
brackets '(e.g. Germany and some European countries)'. I think there is some
implementation in Germany and USA, while in some other countries the option is
explored in pilot projects.

Hans Oonk

Accepted

Corrected as suggested.

4812

5

3

63

64

"Decomposition of the organic matter is promoted about 3-4 times" - this sentence isincomplete - is the intention to say that under aerobic conditions decomposition is 3-4
times quicker than under anaerobic conditions? Please clarify

Fabiano Ximenes

Accepted

Corrected as suggested.

4814

5

3

66

74

This text would flow better if it was placed directly before the text in Line 61 - it seems
out of place now.

Fabiano Ximenes

Rejected

Sequence of current sentences is to explain clearly about MCF. And theparagraph that you pointed out was modified to cover the refinment in thischapter appropriately.

782

5

3

69(→63?)69

Add "an" prior to "abatement measure"Jeffrey Coburn

Accepted

Corrected as suggested.

784

5

3

70

70

Change "This idea had also expanded for" to "This idea has also been expanded for"Jeffrey Coburn

Accepted

Corrected as suggested.

4650

5

3

75

113

Provided the significant amount of literature on the impact of biocover on the methane
oxidation rate, it seems strange not to include this type of managemenet design of SWDSin the guidelines. From a scientific point of view it makes sence to adjust the MCF for
active aerated landfills as less methane is produced. However, for the biocover design,
the process do not change the anaerobic conditions in the lower layers of the SWDS.
Instead the technology aims at oxidising the methane moving upwards passing an aerobic
compost top-layer through which the methane is oxidised to CO2. For this reason, ascientific explanatory approach would be to introduce biocover technology design
specific values for the oxidation rate (resulting from introducing an aerobic
compost/compost like material top cover layer at SWDSs).

Ole-Kenneth Nielsen

Noted

No action can be taken because comment is out of scope of 2019 Refinement.

3432

5

3

75

113

I think the methodology for estimating emissions from aerobic landfills is thin as ice, sice
it is based on two demonstrations. It is at best a Tier 1 approach. When well designed,
the actual MCF can be much lower than 0.4, as suggested by your interpretation of Hrad.
Generally aeration pojects are well monitored and when monitoring data are madeavailable by the landfills, this will open up the possibility of a higher Tier methodology,
based on actual monitoringdata. To facilitate future inventory compiling and review, youneed to mention a Tier-2 /Tier-3 method as well, based on actual on-site monitoring.
Comparable to your (possible) interpretation of Hrad, site specific MCF might beestimated from the CO2/CH4 ratio in the extracted gas as (e.g. by assuming at a certain
moment in time (MCF(t)) being equal to 1-CO2-CH4)/CO2+CH4). an alternative option
is to calculate generation using a conventional FOD model and correct for the amount ofC removed via gas extraction (similar to the correction of emissions for R at
conventional landfills).

Hans Oonk

Accepted withmodification

We address higher tier of methodology for on-site monitoring given in
Appendix 3A.2 and we have added the instruction to refer it in the sentences.

Comment ID Volume

To lineComment

ExpertResponse

3420

5

Chapter From line
3

79

80

You need a clear definition of an aerobic landfill. Line 79-80 can be interpreted as adefinition, but is very vague 'in addition to air injection … certain design of piping … arerequired'. I read this as follows: 'having active air injection is insufficient to be qualified
as an aerobic landfill. In order to qualify, it needs certain design'. This really leaves me
confused. Either you need to elaborate 'certain design' into clear criteria, or you have todefine aerobic landfills simply as a landfill with active air injection.

Hans Oonk

Accepted withmodification

Authors note

3422

5

3

86

88

There are several options to aerate landfills. Low-pressure aeration one of them. I do notunderstand this reference to low-pressure aeration in this sentence. As far as I know, lowpressure aeration is not convincinly demonstrated to be superior (reduced energy use;saving cost of production) to other ways of aerating. On the contrary Van Turnhout in
his PhD-thesis performed CFD-calculations and demonstrated that the traditional designof low-pressure aeration (as promoted by IFAS with vertical wells with relative longfilters, relative far apart) results in inhomogeneous aeration of waste, compared to a moredensily welled system with low filter wells. So low-pressure aeration seems also to resultin inhomogeneus aeration and a relative small proportion of the waste that is actuallysubject to aerobic degradation. Actual design, operation and efficiency of aerobic
landfills is an ongoing discussion and there is no scientific agreement on what systems topromote. Please remove all references to low-pressure aeration from the text.

Hans Oonk

AcceptedBox 3.0A is the information on calculation of MCF for new category at thelevel of current knowledge. Low pressure aeration can categorize to be poorly
managed-active aeration when clearly scientific clarifications are met. In casemonitoring evidence is presented, country specific value or higher Tier can beused. Not only low-pressure aeration, knowledge on any kind of management
related to active aeration are required to develop an appropriate methodology
and parameter in the future .

786

5

3

87

87

Change "...SWDS(reducing..." to "...SWDS (reducing..." [I.e., add space after "SWDS"]

Jeffrey Coburn

Accepted

Corrected as suggested.

788

5

3

87

88

Change "… reducing energy use and savingcost of production." to "… reducing energy
use and processing costs." This provides better parallel structure of terms. If you prefer"production costs", that is OK, but not really producing a product, so the term processing
seems more appropriate. If keep current phrasing (not recommended) need a space
between "saving" and "cost".

Jeffrey Coburn

Accepted

Corrected as suggested.

4646

5

3

88

88

"savingcost of production" should be correted to "saving cost of production" even if it isunclear which cost of production the text refers to

Ole-Kenneth Nielsen

Accepted

Corrected as suggested.

3424

5

3

88

90

You mention that low-pressure aeration projects have shown, that aerobic conversion ofcarbon is 25-75%, based on two demonstrations. These articles specify the compositionof the gas extracted. From the ratio of CH4 and CO2 you can estimate the part of organic
waste that decomposes aerobically (I think it can be calculated as (CO2CH4)/(CO2+CH4)). However this is measured in the extracted gas and is only true forthe part of the waste that is within the influence spheres of the gas wells. it is possible andmaybe even highly likely (see PhD-thesis of van Turnhout), that using low-pressure
aeration in large part of the waste anaerobic conditions remain, methane is generated andemitted. In such a case part of the methane is emitted through the top-surface and does
not end up in the aerations off-gases. I do agree that the range of 25-75% is likely andwhen properly designed, even higher values can be expected. However there isinsufficient R&D to come to such a conclusion.

Hans Oonk

Noted

Considering various comments recieved, this part has been removed. But
authors agree that anaerobic zone would be remained by low-pressure aeration,
and we need the further research and development. Authors have added thesentences regarding with it.

3426

5

3

88

90

The aerobic carbon conversion of 25-75% is based on two demonstrations of lowpressure aeration. Does this imply that the MCFs you propose only refer to low-presure
aeration?

Hans Oonk

Accepted withmodification

Considering various comments recieved, this part has been removed. MCF andthe information in the Box is not corresponding. And MCF is not calculated
from two references. That is just examples of minimum and maximum.

790

5

3

88

91

The sentence starting with "These projects have shown..." seems to have additional,
redundant phrases at the start. I assume one study looked at (aerobic) decomposition ofcarbon and one looked at methane emissions, but it seems simpler to state this more
directly. Recommend complete re-write of this sentence as follows: "These projects haveshown that aerobic conversion of carbon in SWDS can reduce methane emission from25% (Raga and Coussu, 2014) to 75% (Hrad et al., 2013), which corresponds to a MCF
of 0.75 to 0.25, respectively."

Jeffrey Coburn

Accepted withmodification

Considering various comments recieved, this part has been removed.

6206

5

3

90

90

The two literatures presented in line 79 in the FOD (lin e 90 in the SOD) have beenchanged, however still showing very large differences in respect to the reduction of
methane emissions. Probably the literature (Raga ad Cossu, 2014) reflects only not wellmanaged aeration sytems (see line 99 of the SOD) whereas Hrad et al reflects wellmanaged aeration systems? In this case this information should be provided in line 90.

Christoph Lampert

Accepted withmodification

This part has been removed by the comment from other reviewer. Authors
understand this point and the information derived from these references areprovided in table 3.1.

Clarification of definition was given in Box.3.0A (New) and Table 3.1(Updated).

Comment ID Volume

To lineComment

ExpertResponse

Authors note

3430

5

Chapter From line
3

96

100

You need to realise that inventory compilers need to work with this refinement toestimate emissions from aerobic landfills. In the end inventory compilers need to be ble
to justify the proportion of aerobic landfills that are wll managed. Reviewers need to beable to check whether this justification suffices. This process requires a clear definitionof well managed and not well managed. If you are not able to provide such a clear
definition, the refinement will cause a lot of discussions upon implementation andreview. How can a country as e.g. Germany prove to a reviewer, that e.g. 90% of their
aerobic landfills are well managed?

Hans Oonk

Noted

Difinition of the well-managed and poorly-managed SWDS is clearly given intable 3.1. In the countries that dispose the waste into SWDS with different typeof management, such as Japan, survey on the ratio of each category ofmanagement is conducted and the results are reflected to their inventory.

Jeffrey Coburn

Accepted

Corrected as suggested.

Hans Oonk

Accepted

These two references are just examples of minimum and maximum.
Corresponding references are added as well as those given in table 3.1.
Corrected as suggested.

792

5

3

96

96

Change "waste is SWDS" to "waste in SWDS"

3428

5

3

96

98

The best results of aerobic conversion of 50-75% … Where do the 50-75% come from?
The only information gven are the aerobic conversions of Raga (25%) and Hrad (75%)
Please provide a reference.

4648

5

3

97

97

"coversion" should be corrected to "conversion"

Ole-Kenneth Nielsen

Accepted

4172

5

3

97

98

Check spelling errors

Andrea Tilche

Accepted

Corrected as suggested.

794

5

3

98

99

Spacing, puncutation and grammar issues. Should read: "For active aration systems thatare not well-managed, a default MCF of 0.7 was derived from the average of available
literature…"

Jeffrey Coburn

Accepted

Corrected as suggested.

8886

5

5

In Table 5.3A, default CH4 emission factors for pyrolysis of waste vary a lot by different
reactor types and operating temperatures. However, it can be challenging forcountries/cities to find out such level of details about each of their waste incineration
plants. Therfore it is recommended that IPCC also provides some default
situation/emissions factors for each region/nation if it is not possible to determine which
specific ones to use. It is also recommended that IPCC or UNFCCC requests country
level research (or regular surveys) on current incineration technology deployment in eachcountry.

Mingming Wang

Rejected

There are limited data of EF of pyrolysis and gasification, particulary on acommercial scale. To our current knowledge, Table 5.3 A in Final draft provide
data of emission by processs and temperature. To this end emssion factor byregion is not appropriate but country specific data (if availabel) can be used inhigher Tier.

8888

5

5

It is known that uncontrolled burning of domestic waste is a common activity in many
developing regions, and many cities do not have the facilities to carry out adequate
collection and treatment of urban solid waste, so it is recommended that IPCC provides
more guidance on estimating those emissions.

Mingming Wang

Noted

No action can be taken because comment is out of scope of 2019 Refinement.

3270

5

5

1008

1009

Verify bibliographic citation format of table 6A.3

Poot-Delgado Carlos
Antonio

Noted

Not in Volume 5 content. Transferred to Volume 4.

1690

5

5

101

101

Edit "… non-condensible fractions which…"

Robert Lanza

Rejected

non-condensable' is right word, 'not non-condensible'.

1692

5

5

102

102

Edit "… by a quenching process. The gas products are composed mainly of volatileorganic..."Robert Lanza

Accepted

We have changed in line with the comment.

1694

5

5

104

104

Edit "… Solid products of the pyrolysis process include carbon-containing and inorganic
components. The solid products may be burned for energy recovery within the pyrolysis
process or transferred outside of the process for external energy or chemical feedstock orother use."

Robert Lanza

Accepted withmodification

Solid poducts of the pyrolysis process include carbon residues (Char) andinorganic components. The solid products may be combusted in situ for energy
recovery within pyrolysis process or transferred outside for external energy or
chemcial feedstock use

1696

5

5

105

106

Edit "The gas products (pyrogas) may be recirculated back into the pyrolysis process toprovide energy to the pyrolysis reactor, or the gas products may be transferred outside of
the process for external energy or chemical feedstock use."

Robert Lanza

Accepted withmodification

The gas products (Pyrogas) may be recirculated back into the pyrolysis reactor
to provide energy to the pyrolysis reactor or transferred outside for externalenergy or chemical feedstock use.

3272

5

5

1053

1054

Verify bibliographic citation format of table 6A.4B

Poot-Delgado Carlos
Antonio

Noted

1700

5

5

106

107

Delete the sentence "Although CH4 is…"

Robert Lanza

Accepted

We have changed in line with the comment.

1698

5

5

106

109

Edit "… for external energy or chemical feedstock or other use. The energy-supplying
system to the pyrolysis reactor is…"

Robert Lanza

Accepted

We have changed in line with the comment.

1702

5

5

109

109

delete "of organic wastes."

Robert Lanza

Accepted

We have changed in line with the comment.

4926

5

5

111

111

"estimated" should be completed by "and reported"?

Céline Gueguen

Accepted withmodification

We have changed in line with comment 1704.

Not in Volume 5 content. Transferred to Volume 4.

Comment ID Volume

To lineComment

ExpertResponse

1704

5

Chapter From line
5

111

112

Add: Greenhouse gas emissions associated with use of gas, liquid, and solid products ofthe pyrolysis process that are transferred outside of the process for external use, whether
used as fuel, chemical feedstock, or for other purposes, are reported at the point of use of
the products, and are not reported as emissions from the pyrolysis process itself.

Robert Lanza

Accepted withmodification

3242

5

5

113

113

Verify bibliographic citation format

Poot-Delgado Carlos
Antonio

NotedLine 113 in Chapter 5 is the beginning of Box5.0B (New) not related tobibliographic formate

1706

5

5

116

117

Edit "… Depending upon reaction conditions, gasification of solid carbon-containing(organic) wastes are accounted for by four primary reactions."

Robert Lanza

Accepted

Depending upon reaction conditions, gasification of solid organic wastes areaccounted for by four primary reactions.

3244

5

5

121

121

Verify bibliographic citation format

Poot-Delgado Carlos
Antonio

NotedLine 121 in Chapter 5 is the reaction of water gas reaction which is not related
to biblographic format

1708

5

5

123

123

Edit "… These same four reactions would also describe processes for gasification of coal
or coke, Greenhouse gas emissions from coal/coke gasification would be reported as anenergy conversion process under Energy. [emission factors for coal gasification are notbeing provided in the Waste section of the guidelines)

Robert Lanza

Noted

Box5.0B explains gasification process which is in general. If gasification using
coal and coke, this to be reported in energy sector. Pyrolysis and gasification ofwaste if used for energy purposes will be reported in Energy sector as well. We
have clearly indicated in the chapter.

1710

5

5

123

123

Edit" The above gasification reactions reveal that the product gas primarily consists of
H2, CO, and CH4, referred to as synthesis gas (syngas)."Robert Lanza

Accepted

We have changed in line with the comment.

1712

5

5

127

127

Edit "… system following the gasified…"

Robert Lanza

Accepted

We have changed in line with the comment.

1714

5

5

128

128

Edit…" The clean syngas may be used as fuel…"

Robert Lanza

Accepted

We have changed in line with the comment.

1716

5

5

129

129

Edit "… or steam, or may be exported to another process or used as a chemical
feedstock." [there are various other uses for syngas besides being combusted as fuel.]

Robert Lanza

Accepted

We have changed in line with the comment.

1718

5

5

131

131

Edit "… are know as tars, which…"

We have changed in line with the comment.

1776

5

5

1318

1318

What is the definition of "aeration"? An ambiguous term.

1720

5

5

132

132

Edit "… solid products consist of carbon and inorganic components."

1778

5

5

1326

1330

Would "Non-flooded pre-season >365 d" imply the upland-paddy rotation? Although not Kazunori Minamikawa
explicitly mentioned in the text.

Noted

Not in Volume 5 content. Transferred to Volume 4.

1780

5

5

1341

1352

Continuous parameter only for the amount of organic amendment (i.e., not for thedecomposition rate of rice straw (1 vs. 0.19 even 1-day difference)).

Kazunori Minamikawa

Noted

Not in Volume 5 content. Transferred to Volume 4.

1722

5

5

135

136

Edit "… since syngas generated from gasification processes may be used for fuel,exported to another process, or used as a chemical feedstock, CH4 emissions are rarely
expected from the gasification process itself (unless the syngas is vented directly to theatmosphere without being used for fuel or process purposes)." [edited to include thepossibility of uncombusted/unprocessed syngas being vented directly to the atmosphere.
This would be expected to be a rare occurrence.]

Robert Lanza

Accepted withmodification

We have accomodated reviewer's comment and revised some parts.

1724

5

5

136

136

Edit "…Otherwise, the energy-supplying system to the gasification process is…"

Robert Lanza

Accepted withmodification

Paragraph has been rewriten to address clearer understanding

1726

5

5

143

144

Edit "… Since plasma processes are operated…"

Robert Lanza

Accepted

We have changed in line with reviewer's comment.

1728

5

5

145

145

Edit "…nearly completely converted into clean syngas. Reaction residues of the plasma
process consist of inorganic components including slag and metals." [syngas isn't always
used as fuel.]

Robert Lanza

Accepted

We have changed in line with reviewer's comment.

1730

5

5

150

150

Edit "… since syngas generated from gasification processes may be used for fuel,exported to another process, or used as a chemical feedstock, CH4 emissions are rarely
expected from the gasification process itself (unless the syngas is vented directly to theatmosphere without being used for fuel or process purposes)." [edited to include thepossibility of uncombusted/unprocessed syngas being vented directly to the atmosphere.
This would be expected to be a rare occurrence.]

Robert Lanza

Accepted withmodification

We have totally revised the sentence to adopt comment 1730 but have notfollowed the reviewer's suggested sentence.

1732

5

5

151

151

Edit "…Otherwise, the energy-supplying system to the plasma process is…"

Robert Lanza

Accepted withmodification

We have totally revised the sentence to adopt comment 1730 but have notfollowed the reviewer's suggested sentence.

Robert Lanza

Accepted

Kazunori Minamikawa

Noted

Robert Lanza

Accepted withmodification

Authors note
We have elaborated incorporating the sentence into the refinement.

This is not in chapter 5 of Volume 5. Transferred to Volume 4.
We have changed in line with the comment; we use inorganic components and alittle carbon residue.

Comment ID Volume

Chapter From line

6198

5

5

172

1734

5

5

172

To line172

ExpertResponse

On the Table 5.2 (updated), the description of note 3 “When waste is open-burned,
refuse weight is reduced by approximately 49 to 67 percent (US-EPA, 1997, p.79)“ ,related to old default oxidation factor, should be deleted.

Comment

Takefumi Oda

Accepted

Corrected as suggested.

Authors note

Note 6 -- The residue after open burning contains unburned carbon in the form of ash orother solid residue; the fate of the unburned carbon is to be tracked and the GHG
emissions from the disposition of the unburned carbon is to be accounted for in theappropriate category (e,g., landfill).

Robert Lanza

Accepted

Corrected as suggested.

1736

5

5

172

172

Note 6 -- define "SWDS" acronym

Robert Lanza

Rejected

This is a common word in Volume 5 and has been elaborated earlier.

1738

5

5

172

172

Note 6 -- define "DOC" acronym

Robert Lanza

Rejected

This is a common word in Volume 5 and has been elaborated earlier.

1740

5

5

172

172

Table 5.2 -- suggest retitling the table "… CO2 emission factors from conventional
incineration and open burning of waste" to indicate that emission factors for advanced
processes e.g., plasma and gasification, are not included in this table.

Robert Lanza

Rejected

Title is to be in line with 2006 IPCC Guidelines.

1742

5

5

172

172

Has consideration been given to presenting conversion factors (conversion efficiency)
for non-conventional waste management processes, e.g., gasification, plasma, in addition
to the factors presented for conventional MSW incineration and open burning? Suchfactors wouold be useful for inventory compilers assessing the amount of CH4 and CO
and H2 produced from various processes, which could then be useful in combustion
calculations for the Energy section of the inventory.

Robert Lanza

Noted

No action can be taken because comment is out of scope of 2019 Refinement.

6152

5

5

172

173

The oxidation factor of open-burning in Table 5.2 is 58% in the 2006 IPCC Guidelines. I
assume that this value is obtained by the median of upper and lower end of refuse weight
reduction rate mentioned in Note 3 of the table, i.e. (49%+67%)/2=58%. The orginal
document is available at the USEPA website. According to Table 4-4 of the document,
waste sample include fossil waste (e.g. plastics) as well as biomass waste (e.g. paper) andincombustible waste (e.g. metals). If the fraction is recalculated by excluding
incombustible waste (glass/ceramics and metals), the fraction will become 71%. It is
exactly the same as Yamada (2010) in the SOD. I believe the new oxidation factor isreliable.

Naofumi Kosaka

AcceptedThank you for confirmation updated value.

4176

5

5

173

206

Section 5.4.2 presents methane emission factors for new technologies of pyrolysis andgasification. Emission factors for melting plants of MSW is presented in Table 5.3A,
whereas emission factors from laboratory scale studies of pyrolysis and gasification are
shown in Tables 5.3B and 5.4C, respectively. The values in Table 5.4A differ from thosein Tables 5.3B and 5.4C by more than a factor of 1000. The text provides no guidanceon which of these factors should be used. It is also unclear whether the laboratory scale
emissions refer to methane produced or methane leaked from the system. This is aconsiderably need for clarification of which factors and which approaches should be used
for assessing methane emissions from pyrolysis and gasification.

Andrea Tilche

Noted

Table 5.3B and 5.3C were supplied for information not for use as EF ofpyrolysis and gasification plant on a commercial scale. Table 5.3B and 5.3C
were deleted in the final draft to avoid confusion.

1744

5

5

174

176

Edit ".. . Although laboratory-scale data are available from scientific research literature
for CH4 emissions from pyrolysis and gasification of solid wastes (new Box 5.2), very
few data are available for commercial plants of these new technologies."

Robert Lanza

Accepted

We have deleted the table related to laboratory results. See also comment 4176.

3246

5

5

174

177

Verify bibliographic citation format

Poot-Delgado Carlos
Antonio

Noted

Citation are in table 5.3A(New).

1746

5

5

177

177

Suggest that supporting text for New Table 5.3A should describe the mechanism(s) bywhich CH4 emissions arise from gasification/pyrolysis/melting processes, e.g., fugitive
emissions of uncombusted / unpocesses synthesis gas, or other mechanisms.

Robert Lanza

Noted

CH4 emissions from the stack of pyrolysis-melting and gasification-melting
plant are made by incomplete oxidation of the product gases (eg. CH4, C2H6,
H2, and CO) generated from operating the processes. This one is well describedin the BOXs revised text.

Comment ID Volume

To lineComment

ExpertResponse

Authors note

4930

5

Chapter From line
5

183

183

Could you precise if the default CH4 EF proposed in the table 5.3A (new) correspond to
EF for the destruction step (gasifier, pyrolysis reactor) or to the complete plants
including the energy recovery system ?
It is not clear for me as in the pyrolysis scheme you are presenting an "EXTERNAL"
energy use of the pyro-gas and in the gasification scheme you are presenting thatemissions are from the "energy recovery system". However, you are proposing an EF for
both system. In order to increase transparency, you may add the "CO2, N2O, CH4" flow.

Céline Gueguen

Accepted withmodification

We add one sentence in the revised text to answer the comments as follows:"The emissions of greenhouse gases from the combined system with energy
recovery system are reported under the Energy Sector". In a broad sense,
external energy supplying system is the same concept as the energy recovery
system where heat and energy are recovered by heat exchange process. Externalenergy supplying system combusts the product gases to supply the energy toreactor. In boxes related to pyrolysis and gasfication, we mentioned as "Theexternal energy-supplying system to the gasifier is considered as the only
emission source of greenhouse gases in the gasification plant. The emissions ofgreenhouse gases from the energy-supplying system within the gasification
plant are reported under the Energy Sector" in the revised text.

1748

5

5

183

183

Previous statements (e.g., line 136, line 151, line 200) indicate that the energy-supplying
system for the gasification/pryolysis process is the only source of GHG emissions fromthe process. If that is the case then the emission factors for CH4 in Table 5.3A should all
be zero. Suggest editing line 136, line 151, line 200, and etc. to indicate that some CH4
emissions are anticipated to be emitted directly from the gasification/pyrolysis processes.

Robert Lanza

Accepted withmodification

In case product gases from pyrolysis-melting and gasification-melting plant areused internally for the purpose of using as fuel to supply energy to system, someCH4 could be emitted as a result of its incomplete oxidation. The CH4
emissions from the internal use of product gases would be reported under
Energy Sector not Waste Sector if pyrolysis and gasification process withenergy recovery system. On the other hand, the product gases can be collected
and transported to outside for using as fuels. In case of the external uses of
product gases, the CH4 emission can be anticipated as a result of its incomplete
combustion by external combustion facilities. The CH4 emissions would bereported under Energy Sector not Waste Sector.

1750

5

5

183

184

Suggest that supporting text for New Table 5.3A should describe the specificpyrolysis/gasification/melting processes that are described in the references Yoon (2016)
and GIO (2017), potentially including process flow diagrams for each processe. This
information would support the text discussion of the mecnahism(s) by which CH4emissions arise from the gasification/pyrolysis/melting processes, e.g., fugitive emissionsof uncombusted / unpocesses synthesis gas, or other mechanisms.

Robert Lanza

Noted

We have already described the generation mechanisms of CH4 from pyrolysis
and gasification in the boxes 5.0A and 5.0B. In addition Table 5.3A has beenrevised for better understanding.

1752

5

5

183

184

The table heading refers to "CH4 emission factors (g/kg pyrolyzed waste on a wet basis)"but only one of the two processes listed in the table is a pyrolysis process.

Robert Lanza

Accepted

We will change the table heading to : CH4 emission factors (g/kg on a wetbasis).

1754

5

5

183

184

Reference GIO (2018) Page 7-34 indicates that " Different emission factor is used foreach furnace type (shaft furnace, fluidized bed, and rotary kiln) for waste
gasification/melting, based on (Reference #21) in the GIO (2018)

Robert Lanza

Accepted withmodification

We have updated our information in line with the reviewer's comment.

1756

5

5

183

184

Reference #21 in GIO (2018) is "Survey Study on Improving the Accuracy of Emission
Factors for Greenhouse Gas Emissions from the Waste Sector, 2010" Suggest accessing
2010 reference to assess availability of emission factors for shaft furnace, fluidized bed,
and rotary kiln processes.

Robert Lanza

Accepted withmodification

We have updated our information in line with the reviewer's comment.

1758

5

5

183

184

Reference Yoon (2016) title indicates that the subject matter of the reference is N2Oemission factors, not CH4 emission factors, suggest clarifying

Robert Lanza

Accepted

1760

5

5

187

187

Edit "… Information on CH4 emissions…"

3248

5

5

193

194

Verify bibliographic citation format

1762

5

5

193

194

1764

5

5

199

1766

5

5

200

The title of the table was wrong. So, we have changed the CH4 emission factor
to N2O emission factor in the revised text.

Robert Lanza

Rejected

We cannot understand reviewer's comment.

Poot-Delgado Carlos
Antonio

Noted

Box 5.2 (New) was revised and 3 references were quoted with standard format.

Emission factors in Tables 5.3B and 5.3C are a factor of 10 E+04 higher than theemission factors in Table 5.3A (derived from commercial operating data cited in GIO
2018). Suggest providing rationale/criteria for when to use the emission factors in Table
5,3A and when to use the emission factors in Table 5.3B and 5.3C. laboratory scale data
may not be representative of commercial operations

Robert Lanza

Noted

Table 5.3B and 5.3C were supplied for information not for use as EF ofpyrolysis and gasification plant on a commercial scale. We consider dropping
Table 5.3B and 5.3C to avoid confusion .

199

Edit "… collected and may be used either as fuel or as chemical feedstock…"

Robert Lanza

Accepted withmodification

We totally rewrote the box and decided to only explain the CH4 emission
pattern in the box, not used for fuel and chemical feedstock.

200

Line 200 indicates that CH4 emissions are not expected from pyrolysis processes. This
statement (see also line 13 and line 151) seems to be inconsistent with the presentation ofCH4 emission factors in Table 5.3A and particularly with the CH4 emission factors in in
Tables 5.3B and 5.3C. Suggest that text be added to indicate when (under what criteria)
the emission factors in Table 5.3A and Table 5.3B and Table 5.3C should be used.

Robert Lanza

RejectedBox 5.2 (New) was revised. Even if the CH4 emissions would be negligible
during the pyrolysis-melting and gasification-melting operation, those were
measured from the stacks and can be used as CH4 EFs.

Comment ID Volume

To lineComment

ExpertResponse

Authors note

1768

5

Chapter From line
5

201

201

Suggest including a discussion here that the syngas may not be combusted at the same
physical location at which it is produced, and that the CO2 and CH4 emissions fromsyngas combustion should be attributed to the specific Energy sector location in which
the combustion takes place and not reported under "waste incineration" in the Waste
sector of the inventory.

Robert Lanza

Noted

The Final draft explain clearly that the refinement provided information forCH4 and N2O emission from pyrolysis and gasification that is directly emit toatmosphere.

7170

5

5

226

226

“ a few official data...” change to be "few official data..."Luhui Yan

Noted

There are data for CH4 and N2O emission factor from new technologies.

1770

5

5

232

233

Reference GIO (2018) Page 7-34 indicates that " Different emission factor is used foreach furnace type (shaft furnace, fluidized bed, and rotary kiln) for waste
gasification/melting, based on (Reference #21) in the GIO (2018)

Robert Lanza

Accepted

We have updated our information in line with the reviewer's comment.

1772

5

5

232

233

Reference #21 in GIO (2018) is "Survey Study on Improving the Accuracy of Emission
Factors for Greenhouse Gas Emissions from the Waste Sector, 2010" Suggest accessing
the 2010 reference to assess the availability of separate emission factors for shaft
furnace, fluidized bed, and rotary kiln processes.

Robert Lanza

AcceptedSame as comment 1756.

3250

5

5

260

261

Verify bibliographic citation format

Poot-Delgado Carlos
Antonio

Rejected

260-261 is the references.

1782

5

5

3167

3198

Citation from a published paer is crucial to this report. Request review after the
publication because we cannnot know the details of the annex 5a.2.

Kazunori Minamikawa

NotedThis comments is not with Volume 5 content. Transferred to Volume 4.

3252

5

5

387

435

Verify bibliographic citation format

Poot-Delgado Carlos
Antonio

Noted

3254

5

5

438

439

Verify bibliographic citation format of table 6.3

Poot-Delgado Carlos
Antonio

Noted

3256

5

5

469

470

Verify bibliographic citation format of table 6.12

Poot-Delgado Carlos
Antonio

Noted

1652

5

5

48

48

Edit "…and have become important in…"

Robert Lanza

Accepted

We have changed in line with the reviewer's comment.

1654

5

5

50

50

Edit "… oxidation factors for the…"

Robert Lanza

Accepted

We have changed in line with the reviewer's comment.

1656

5

5

51

51

Edit "… based on experimental data, and including uncertainty."

We have changed in line with the reviewer's comment.

3258

5

5

528

529

Verify bibliographic citation format of table 6.13

1658

5

5

53

53

1660

5

5

54

54

Robert Lanza

Accepted

Poot-Delgado Carlos
Antonio

Noted

Edit "… are generally combusted for use as fuel either on site or off site."

Robert Lanza

Accepted

We have changed in line with the reviewer's comment as follows: Since gas
products containing CH4 and N2O produced by new technologies such as
pyrolysis, gasification, and plasma processes are collected and used mostly as
fuel or chemical feedstock, in situ CH4 and N2O emissions from the newtechnologies are expected to be quite low unless gas products containing CH4 isdirectly vented to the atmosphere. Greenhouse gas emissions resulting from theoutside uses of gas, liquid, and solid products generated from new technologies
are not reported as those from the new technologies themselves, but at the pointof their use.

Edit "… from the combustion of fuels derived from these new technologies are …" The
text should make a distinction here between the reporting the [residual] CO2 emissions
that would arise from the waste thermal treatment process itself and the CO2 emissions
that would arise from combusting the fuel produced by the thermal treatment process.
The fuel created by the waste thermal treatment process may be exported (e.g., CH4 fed
into a natural gas pipeline) and burned off site, and in this case the CO2 emissions fromthe combustion of the fuel would be reported at the point of fuel use (e.g., the natural gas
comsumer), not at the point of fuel generation (i.e., the waste thermal treatment process).
Also, certain thermal treatment processes (e.g., pyrolysis) produce liquid products(aliphatic and aromatic hydrocarbons) that may not be burned for energy but rather may
be used as chemical feedstocks or for other purposes. Thereby the total CO2 emssions
from conventional incineration of the waste would be higher than the total CO2
emissions from thermal treatment (e.g., pyrolysis) of the waste, as some of the carbon
content of the waste would be converted into liquid products for commerical use and not
be converted directly into CO2 emissions from the thermal treatment process.

Robert Lanza

Accepted withmodification

We have changed in line with the reviewer's comment as follows: Since gas
products containing CH4 and N2O produced by new technologies such as
pyrolysis, gasification, and plasma processes are collected and used mostly as
fuel or chemical feedstock, in situ CH4 and N2O emissions from the newtechnologies are expected to be quite low unless gas products containing CH4 isdirectly vented to the atmosphere. Greenhouse gas emissions resulting from theoutside uses of gas, liquid, and solid products generated from new technologies
are not reported as those from the new technologies themselves, but at the pointof their use.

Comment ID Volume

Chapter From line

To lineComment

ExpertResponse

Robert Lanza

Rejected

Authors note

Poot-Delgado Carlos
Antonio

Noted

Robert Lanza

Rejected

We have deleted this sentence as a result of incorporating 2006 IPCC
Guidelines.

Accepted

Refer to comment '1764'

1662

5

5

56

56

Edit "… Incineration is defined in the …"

We have deleted this sentence as a result of incorporating 2006 IPCC
Guidelines.

3260

5

5

561

562

Verify bibliographic citation format of table 6.14

1664

5

5

58

58

Edit "… definitions of…"

1666

5

5

60

60

Edit "… process that thermochemically converts…"

Robert Lanza

1668

5

5

65

65

Edit "… is referred to as synthis gas (syngas) and is mainly used as fuel. Syngas may
also be used as a feedstock for chemical production.

Robert Lanza

1670

5

5

67

67

Edit "… The highly reactive…"

Robert Lanza

Accepted

We have changed in line with the reviewer's comment.

1672

5

5

72

72

Edit "… plastics, and they are also used to treat MSW to avoid generation of air
pollutants that would arise from conventional MSW incineration."

Robert Lanza

Accepted

We have changed in line with the reviewer's comment.

3262

5

5

744

745

Verify bibliographic citation format of table 6.17

Poot-Delgado Carlos
Antonio

Noted

1674

5

5

76

76

Edit "… are available for the…"

Robert Lanza

Accepted

We have changed in line with the reviewer's comment.

1676

5

5

80

80

Edit "… both with separate reporting of fossil and biogenic carbon dioxide emissions."

Robert Lanza

Rejected

This sentence was adopted from 2006 guideline

3264

5

5

846

847

Verify bibliographic citation format of table 6.18

Poot-Delgado Carlos
Antonio

Noted

1678

5

5

85

86

Edit "… collected and used either as fuel or as chemical feedstock…"

Robert Lanza

Rejected

1680

5

5

87

87

Edit "… unless the CH4 produced by the thermal treatment process is directly emitted tothe atmosphere without being captured for fuel or feedstock use."

Robert Lanza

Accepted withmodification

We have changed as follows: Since gas products containing CH4 and N2O
produced by new technologies such as pyrolysis, gasification, and plasma
processes are collected and used mostly as fuel or chemical feedstock, in situ
CH4 and N2O emissions from the new technologies are expected to be quite
low unless gas products containing CH4 is directly vented to the atmosphere.

1682

5

5

87

88

Edit "… CH4 (and CO2, and N2O) emissions from combustion of the fuel produced bywaste thermal treatment processes may be estimated using the emission factors inVolume 2.

Robert Lanza

Accepted withmodification

We have changed as follows: Greenhouse gas emissions resulting from theoutside uses of gas, liquid, and solid products generated from new technologies
are not reported as those from the new technologies themselves, but at the pointof their use.

1684

5

5

88

89

Edit "When the CH4 and other gas products generated by the thermal treatment process
are not recovered for fuel or feedstock use, it is good practice to estimate both the CH4
and CO2 emissions from the thermal treatment process in the Waste sector." In the caseof a waste thermal treatment technology that does not collect the syngas for use as fuel orfeedstock, there would be both CH4 and CO2 emissions directly from the thermal
treatment technology, as the syngas generally would contain both CH4 and CO2 (as well
as CO and H2). If would be highly unusal to operate a thermal treatment syngas plant
without actually collecting the syngas, but the inventory method should account for the
possibility of the release of uncollected/uncombusted syngas from waste thermal
treatment processes.

Robert Lanza

Accepted withmodification

We have changed as follows: Greenhouse gas emissions resulting from theoutside uses of gas, liquid, and solid products generated from new technologies
are not reported as those from the new technologies themselves, but at the pointof their use.

3266

5

5

915

946

Verify bibliographic citation format

Poot-Delgado Carlos
Antonio

Noted

1686

5

5

92

92

Edit "… is a reductive and…"

Robert Lanza

Accepted

We have changed in line with the reviewer's comment.

1688

5

5

93

93

Edit "… molecular weight compounds…"

Robert Lanza

Accepted

We have changed in line with the reviewer's comment.

3268

5

5

951

952

Verify bibliographic citation format of table 6A.1

Poot-Delgado Carlos
Antonio

Noted

4928

5

5

96

96

"commingled" could be replaced by "mixed" ?

Céline Gueguen

Rejected"Commingled" is common word used in waste field

7492

5

6

General comment: There will not be any updates to Table 6.5? Some of the values in thetable are close to 20 years old which would motivate an update.

Klara Westing

Rejected

No action can be taken because comment is out of scope of 2019 Refinement.

We have changed in line with the reviewer's comment.

Refer to comment 1764.

Comment ID Volume

ExpertResponse

Authors note

6228

5

Chapter From line
6

To lineGeneral remark: For the methane emissions the number of literature justifying the
introduction of this new source is very small. The new emission factors resp. MCF
factors or emissions from aerobic waste water treatment systems shall be as robust as
possible in order to avoid future adjustments of the MCF. The derivation of the MCF
shall be included in the guideline (see also remark above line 22).

Comment

Christoph Lampert

Accepted withmodification

The literature clearly identify that there are methane emissions associated withcentralized aerobic treatment systems, and as such, it would be inappropriate toretain an emission factor of zero. An annex has been added to the document topresent the derivation of the revised emission factor.

6230

5

6

Equation 6.10 (TOTAL NITROGEN IN DOMESTICWASTEWATER BY
TREATMENT PATHWAY) and Table 6.13 (DEFAULT FACTORS FOR DOMESTICWASTEWATER) shall be reconsidered as total N-flows most likely are significant
overestimated (see also remark above in the lines 25 and 26).

Christoph Lampert

Rejected"DEFAULT FACTORS FOR DOMESTIC WASTEWATER" is not Table 6.13
but Table 6.16. The authors disagree that total N-flows are significantly
overestimated. However, we have updated this table to include geographicbased data obtained from FAOSTAT. In addition, inventory compilers can use
country-specific data to calculate total nitrogen entering treatment plants, if
such data exist for a Tier 2 or Tier 3 methodolodgy.

8890

5

6

Figure 6.1 only provides two types of treatment of sludge, which is not aligned with thesludge pathway given in Box 2.1A of Volume 2. Please clarify and consider making
reference to the pathway given in Box 2.1A.

Mingming Wang

Accepted

Figure 6.1 has been updated and Box 2.1A has been removed.

8892

5

6

Figure 6.1a only provides a range of values for each country, which is not easy to use.
Please also provide exact figures in a table format if possible.

Mingming Wang

Rejected

The detailed data are provided in "Annex 6A.1 Summary data for pit latrineuse, no sanitation facility, and groundwater use by country"

3500

5

6

1037

1052

I am not an expert in N2O-emissions and as a non expert, I like this approach. I would
like to refer to the additional information on N2O-emissions from WWTP in the PhDthesis of Delré. In table 3 and 4 Delré presents information from literarture. The bestinterpretation of Delrés measurement is given in the supporting information of the article
https://doi.org/10.1016/j.scitotenv.2017.06.177 (for copyright reasons, I can not give
you this supporting information).

Hans Oonk

Noted

Thank you for your information. Unfortunately the recommended scientificpaper reported GHG emissions including on-site sludge incineration. So thesedata cannot be included in our EF data source.

4184

5

6

1039

1051

Annex 6A.5 argues for different nitrous oxide emission factors for BNR and non-BNR.
However, this difference relies on one single data point, which could be considered an
outlier. The text does not include a statistical analysis of whether these emission factors
are statistically significant. This would require some transformation of data, since thedata is clearly not normal distributed. There is considerable reason to doubt whether
there is data to substantiate a difference in emission factors between BNR and non-BNR.

Andrea Tilche

Accepted

We revisited outliers in the data, and decided to remove the data point
addressed by the commenter. In addition, we have reviewed the difference in
EF for BNR versus non-BNR systems and are now providing one N2O EF forcentralized wastewater treatment plant.

4182

5

6

1048

1051

This text develops

Andrea Tilche

Noted

3434

5

6

127

155

The overview of changes from the 2006 Guidelines to the 2019 refinement is incomplete.
One change compared to the 2006 GL is removal of 'I' from the methodology. This is not
mentioned, nor motivated in the SOD. Please mention this and motivate this change.

Hans Oonk

Rejected

The correction factor "I" has not been removed from the guidelines. It is now
located in Equation 6.3A.

3436

5

6

127

155

Another important change compared to the 2006 GL are indirect emissions fromdischarge of TOW with the effluent of WWTP. Please include this in the overview ofchanges.

Hans Oonk

Accepted withmodification

Changes compared to the 2006 Guidelines have been updated and are now
located in Section 6.1.5.

3490

5

6

156

863

You encourage countries to quantify both CH4 and N2O emissions for separate
pathways: direct discharge, non-BNR-WWTP; BNR-WWTP; septic tanks. Table 6.3 (EFCH4) and 6.15 (EF N2O) are in this version well synchonised. However tables 6.12 6.13
and 6.17 have different terminology. Where Table 6.3 and 6.15 use BNR and non-BNR,
6.12, 6.13 and 6.17 uses 'secondary' and 'tertiary'. Please use similar terms throughout, so
BNR/non-BNR or secondary/tertiary. A definition of 'secondary' and 'tertiary' is only
provided below 6.13 and 6.17. If you decide to keep this terminology, please introduce
this definition as well below Table 6.12. Table 6.3 and 6.15 also include the effect of'primary treatment' only. The pathway of 'only primary treatment' is no part of 6.3 and6.15. If you think 'primary treatment only' is a relevant pathway to consider, please
include EF for CH4 and N2O in 6.3 and 6.15 (so countries will collect activity data forthis). If not, please remove this pathway from tables 6.12, 6.13 and 6.17. You might
consider to combine all tables into one big table with overview of pathways, with CH4
and N2O-EF per pathway; C and N removal efficiencies, default sludge generation, etc.

Hans Oonk

Accepted

We have updated the text to ensure all terms are defined and that there issynchronicity between the tables.

6210

5

6

162

162

In the undermost box of Figure 6.1 on "Sludge treatment at Wastewater Treatment Plant"
the treatment "aerobic stabilisation" shall be added as this treatment is typically used atsmall treatment plants

Christoph Lampert

Accepted

Figure has been updated.

Comment ID Volume

To lineComment

ExpertResponse

Authors note

6212

5

Chapter From line
6

177

179

It is said that there is insufficient data to quantify emissions directly from the sewercollection system, the emission factors presented for centralised
treatment plants account for dissolved methane entering the treatment systems. How canthe emission factors presented include these emissions as a quantification is not possible
due to insufficient data?

Christoph Lampert

Rejected

6214

5

6

192

195

There is also literature showing, that the major part of N2O-emissions stems from thedenitrification step - the literature enclosed includes a broad overview on N2O emissions
from sewage treatment plants.

Christoph Lampert

Accepted withmodification

There are insufficient data to reflect emissions that occur directly fromcollection systems as wastewater is collected and transferred to a centralized
treatment plant. However, we recognize that emissions data used to develop
EFs for centralized treatment plants include a contribution of dissolved CH4that is being generated within the collection system and transferred to thetreatment plant. Therefore, the treatment plant EF does include suchib tiThet sentence
has been revised to say that both nitrification and denitrification
are the important reaction for N2O emission.

3494

5

6

221

224

Definition of BNR. You need to realise that the methodology is used by people,
performing inventories. Such a person has different topics to work with and is notnecessarily an expert on waste water treatment. I guess > 95% of the processes you referto are units for nitrification/denitrification, so you might include'nitrification/denitrification' in your definition. Does it include others as well (e.g.
Anammox?)? I am also confused by the 'and' in nitrogen and phosphorus. If a WWTP
removes nitrogen, but not phosphorus, does is still qualify as BNR? My proposal would
be: These “biological nutrient removal” (BNR) systems have unit-operations, dedicatedto biological removal of nitrogen. In most cases, BNR will consists of zones fornitrification and denitrification, but other processes might also be relevant (e.g.
Anammox). WWTP with BNR is often referred to be as part of 'tertiary treatment' or'more stringent treatment (EU-UWWTD)'. In other definitions, BNR is considered partof secondary treatment.

Hans Oonk

Accepted

Text has been revised based on the comments.

3496

5

6

222

223

You write: ' which also results in higher potential for CH4 and N2O emissions.' BNR isdemonstarted to result in higher N2O-emissions. Its impact on CH4-emissions is unclear
and at the moment insufficient information is available to distinguish between CH4-EF
for WWTP with BNR and without BNR. please adapt the text accordingly.

Hans Oonk

Accepted

Text has been revised based on the comments.

7172

5

6

234

234

"24h to 72hr" change to be "24hrs to 72hrs"?

Luhui Yan

7174

5

6

266

266

"CH4irrespective" change to be "CH4 irrespective"

Luhui Yan

Accepted withmodification
Accepted

3438

5

6

269

269

The title of paragraph 6.1.1 should be 'Changes compared to the 2006 Guidelines'.

Hans Oonk

Rejected

This is incorrect. Section 6.1.1 of the SOD is related to the original section in
the 2006 Guidelines, which compared the 2006 Guidelines to the 1996
Guideline and Good Practice Guidelines. There is no update to this section;
however, for ease of reading, this section has now been moved to Section 6.1.4
and a new section (Section 6.1.5) has been added to discuss the changes of the2019 Refinement related to the 2006 Guidelines.

3440

5

6

329

329

Third box at the left: 'Are measurements available'. This is not clear to me. Whatmeasurements do you refer to? Measurements of methane emissions from individual
pathways? Or measurements of amount of TOW discharged via individual pathways.
With regards to the latter, many countries have information available on TOW treatedper WWTP (E.g. all EU-countries have information available per WWTP of PE treated
per year, through monitoring of implementation of the UWWTD). If you want countries
to use measured TOW per discharge pathway, before they start estimating TOW via a percapita default values, you should include this guidance in the text. please be aware thatsome countries will have statistics available on PE treated/removed; others may havemeasurements of COD or BOD available.

Hans Oonk

Accepted withmodification

The decision trees for both methane and nitrous oxide have been updated tomore clearly define Tier 1, Tier 2, and Tier 3 approaches. If a country has
country-specific data on TOW or N discharged via individual pathways, they
may use a Tier 3 approach to estimate emissions from treatment and/or
discharge.

The text has been updated.
The text has been updated.

Comment ID Volume
6200

5

Chapter From line
6

To line329, 564, 62

Comment

ExpertResponse

Authors note

In the termination of the decision trees, there are a description of “Are activity data
available to categorize discharge by type of waterbody？” or “Are activity data available
to categorize discharges to hypoxic environments?” when we use Tier 1a emission
factors.

Takefumi Oda

Accepted withmodification

We have revised our previous approach and have now provided additional
guidance on the types of activity data which allow for receiving environments to
be categorised as "nutrient-impacted" or otherwise. We have also provided
guidance on the types of activity data and where to find existing data (including
examples of existing databases online for some global regions) to help classify
wastewater discharge receiving environments by type ("nutrient-impacted" or"non-impacted"). The methodology has also been revised to a Tier 3 method
and provided with new guidance as above.

1) It is necessary to provide a guidance to categorize and collect activity data for eachwaterbody to which wastewater is discharged.
2) To elaborate adoption of the new EFs, it is necessary to develop an advanced
methodology by using information of relationship between each source of wastewater
and waterbody type to which wastewater is discharged. Please provide the realistic
methodologies, If you have already prepared.
3) Related to the estimation of N2O emissions from discharged wastewater, Hypoxic
environment is not always stable condition but can often irregularly
appear/disappear/move in public water. Therefore, the severe adoption of suchmethodology is thought to be not easy. Providing current findings related to this matteris welcomed.
4) It is thought to be that adoption of EFs of Tier 1 (or average of Tier 1 and Tier 1a) is
enough for all AD of non-key category.
5) Iｔ is suggested that the decision tree is divided into those for “treatment” and“discharge” to elaborate selection of methodology to estimate emissions from discharged
wastewater if the refinement focuses on the elaboration of emissions from wastewater
discharge.
3442

5

6

334

335

The SOD reads 'For systems for which […] appropriate statistics are available it is goodpractice ….'. Note: the refinement gives guidance to calculate emissions on a nationallevel. For performing the calculation according to this SOD, national statistics are
required on (i) amount of sludge generated and (ii) the way sludge is treated on-site (x%composting, y% anaerobic digestion, z% drying, etc.). Most countries will not havethese statistics available. What guidance do you give when these statistics are notavailable. The 2006 Guidelines suggest that in such a case, S can be assumed to be 0.
Does this still apply in the 2019-refinement? And if so, did you really solve the problem
with possible negative emissions?

Hans Oonk

Rejected

The text has been revised to remove the reference to whether or not appropriate
statistics are available; countries must estimate the amount (mass) of sludge
they generate from wastewater treatment. Data are available for a number ofcountries in the Eurostate and OECD databases, and other country-specificdatabases, and Annex 2A.1 gives information on management of municipal
solid waste. Using a default value of zero for "S" is no longer applicable.

3444

5

6

338

339

The SOD reads 'calculate emissions and any CH4 recovery directly associated'. The
methodology in chapter 4 and the defaults in table 4.1 do not use nor produce data on
CH4-recovery.

Hans Oonk

Accepted

Text was changed.

7480

5

6

340

340

Spelling error; "reports" should be "report"

Klara Westing

Accepted

The text has been updated.

4178

5

6

340

340

Change "reports" to "report"

Andrea Tilche

Accepted

The text has been updated.

Comment ID Volume

To lineComment

ExpertResponse

Authors note

3446

5

Chapter From line
6

349

349

In the SOD you propose to calculate indirect methane emissions due to discharge of
effluent from WWTD to open waters. This might affect equation 6.1. TOW enters a
WWTP/setic tank/etc and part of it is removed as sludge; part of it is discharged with theeffluent. The remainder is biologically mineralised and the MCF describes what part ofmineralisation takes place via anaerobic degradation (at least this is my understanding).
For WWTP, only small part of TOW is discharged with the effluent, the the error here issmall. But for septic tanks it becomes important: 50% of TOW is removed as sludge(when a septic tank is in compliance with the sludge removal instruction, see new
equation 6.3A) and 50% of TOW ends up in the effluent (see New table 6.13). Still
application of equation 6.1/table 6.3 results in 25% of TOW being emitted as methane.
So in total 125% of TOW leaves the septic tank (either as sludge, with the effluent or as
gas through mineralisation). You might rethink equation 6.1 to be something like"emissions = MCF *B0* (TOWinfluent - S - TOWeffluent)". Alternatively, for septic
tanks, when sludge production is known and the TOW concentration in the effluent is
known, methane emissions can be quantified from the mass balance (emissions = MCF*B0* (TOWinfluent - S - TOWeffluent), assuming that conversion of TOW to gas
proceeds for 100% through anaerobic processes (so MCF=1).

Hans Oonk

Rejected

For septic systems, the MCF of 0.5 has been derived from literature
measurement data (Leverenz et al, 2010; Diaz-Valbuena et al, 2011; Truhlar etal, 2016) accordingly with the default Bo, considering that the Activity Data is(TOW-S). So, changing the activity data would result in new MCF for septic
systems and all other treatment/discharge pathways. Moreover, the total TOW
leaving the septic tank is not 125%. For example, lets consider that 100 kg of
TOW is entering the septic tank. With the application of the new Equation 6.3C,
using the default F value of 0.5, the amount of TOW removed as sludge(Sseptic) is 25 kg, and therefore 75 kg remains in the tank. The MCF of 0.5(derived from measurements and consistent with the activity data) means that
50% of the TOW remaining in the septic tank (37.5 kg) is subject to anaerobic
decomposition and methanogenesis (NB. the MCF is not the same as themethane emission factor "EF" of Table 6.3 and applying the EF to this example
does not produce a 25% methane yield from TOWseptic as the commentsuggests, but rather closer to 10% of TOWseptic being emitted as methane once
you apply the EF). A new Equation 6.3D was also added to allow the estimationof TOW discharged in septic tank effluent (TOW_EFF treat) which can then be
applied in Equation 6.1 for CH4 emissions estimation from both the septic tankunit and discharged effluent.

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Our remarks on equation 6.1A (lines 259 to 261 in the FOD) have not been included.
This equation seems to be incomplete if waste water is treated: (this is also true for the2006 guideline): In a typical modern waste water treatment plant about 55% of the BOD
ends up in the sludge and 10% is in the discharge. But: about 35% of the TOW is used
up by the biomass and leaves the system as CO2 which is not included in the formula.

Christoph Lampert

Rejected

The EF is estimated as Bo multiplied by the MCF. Bo represents the theoreticalmaximum CH4 that can be liberated from a type of waste, which by definition
includes complete decomposition. The estimation of Bo already includes thefact that a part of the organic load is emitted as CO2 (see annex 6A.1). Carbon
dioxide (CO2) emissions from wastewater are not considered in the IPCC
Guidelines because these are generally derived from modern (biogenic) organic
matter in human excreta or food waste of biogenic origin and should not be
included in national total emissions.

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One of my main problems with the SOD is that methane collected from anaerobic
digesters and methane from sludge production is treated differently. This implies thatinventory compilers need to collect data on methane collection from WWT&D in asegregated way. Assume a case in which emissions from waste water ponds and sludge
treatment are calculated seperately. Emissions from the waste water ponds are calculatedusing equation 6.1. R refers to methane recovered from the waste water ponds
themselves (e.g. in case anaerobic treatment is part of the process) and is subtracted fromgross emissions. Emissions from sludge are calculated using equation 4.1. R from sludge
is included in the EF and is not subtracted from gross emissions. Countries will haveproblems to understand the correct way of calculating from the your guidance. If you
decide to keep the calculation this way, I think you will need to describe this much moreclearly in the 2019 refinement.

Hans Oonk

Noted

As wastewater treatment in ponds (anaerobically or aerobically) and sludge
digestion are separate pathways, and if every pathway is calculated separately(including R, which in most cases is 0) as it is proposed in this refinement,
there should not be a problem with emission estimation.

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Emissions from the waste water ponds are calculated using equation 6.1. R refers tomethane recovered from the waste water ponds themselves (e.g. in case anaerobic
treatment is part of the process) and is subtracted from gross emissions. Emissions fromsludge are calculated using equation 4.1. R from sludge is included in the EF and is not
subtracted from gross emissions. So the 2019 refinement requires more information on
R, than the 2006 Guidelines: it requires information on a national level, what part of R
comes from the waste water ponds and what part of R is due to anaerobic digestion ofsludge (one is subtracted and the other one is not). What guidance do you give tocountries, that do have information on total R, but not on R from water ponds and sludge
treatment separately.

Hans Oonk

Rejected

The 2019 refinement does not require additional information. The methodology
in chapter 6 allows estimatioin of emissions as in IPCC 2006 guidelines.
Use of the Chapter 4 methodology is simpler as it does not need R, just amountof sludge undergoing anaerobic digestion.

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Calculation of emissions via the 2019 refinement requires on a national level, what partof R comes from the waste water ponds and what part of R is due to anaerobic digestionof sludge (one is subtracted and the other one is not). The CRF-tables provide
information, relevant for quantification of emissions. The current version of the CRFtables only contain information on total methane flared and utilised (Table 5D, cell H10and I10 for domestic waste water and cell H11 and I11 for industrial waste water). When
your method of calculating emissions is accepted, the CRF-table 5D should be expanded
and both methane collected at waste water ponds and sludge treatment should bereported separately.

Hans Oonk

Rejected

From the point of reporting (methane flared / utilised) there is no difference if
the methane was captured from waste water treatment or from sludge digestion
and there is no need to expand CRF Table 5D as suggested.

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Methane recovered from the waste water ponds is treated differently from methane
recoverd during sludge treatment. One is included in the EF/MCF; the other one not.
This will cause problems, which are avoided by treating R from both parts of the system
the same way. My preference would be to include R in the EF/MCF, with EF/MCF for
both parts describing emissions (generation-recovery), comparable to eq. 4.1. Additional
advantage is that this approach is more accurate that the alternative, because propagationof errors is much less advantageous in the alternative. In this case R is still reported in the
CRF-Tables 5D, but only for information purposes (comparable to R for anaerobic
digestion of solid waste in Table 5B).

Hans Oonk

Rejected

Incorporation of R into EF/MCF is not possible in general guidelines. The
range of technologies used is very wide and also option for capturing methane
are wide. Such approach would result in a huge number of technology specific
EF/MCF.
However this approach could be used in a country-specific model.

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Please make clear that B0 is the theoretical methane generation, assuming all organic C
to be convcerted to biogas. B0 is not the same as the biological methane potential, which
excludes organic material, that does not degrade under anaerobic conditions. 'Improving'
B0 can only be done by determining the average composition of TOW (CxHyOzNaSb)
and calculate the theoretical amount and composition of its biogas upon complete
conversion via the Busswell-equation. Refer to appendix 6A.3

Hans Oonk

Accepted withmodification

Discussion in the text is revised to make clear that Bo represents the complete
conversion of organic C to biogas. No country-specific calculation on domestic
Bo is encouraged by the authors as that would also require an update to the
MCF for each specific type of treatment system. A clarification has been added
to mention that "Inventory compilers should compare country-specific
COD/BOD ratio in domestic wastewater to IPCC default values of 2.4."

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The suggested default value of 0.6 kg CH4/kg BOD is totally unrealistic. As shown inAnnex 6A.1 the theoretical value is 0.25 kg CH4/kg BOD removed. The figure 0.6 kg
CH4/kg BOD is formed by multiplication of 0.25 with 2.4 which is a common ratio
between COD and BOD in domestic wastewater. But with this operation all organic
matter (measured as COD) is supposed to be degradable (normally measured as BOD,
the part of COD that is readily degradable). Of course it could be stated that given
enough time all organic matter will be degraded, but this takes at least several thousand
years. It is probably not even true under anaerobic (methane producing) conditions, lookat peat and crude oil.In the different listed systems in Table 6.3 the actual retention timeis in most cases from 10 hours to one year. During this time it is very unlikely that morethan BOD is degraded, giving methane. This means that the actual maximum methane
formation is 0.25 x BOD. Using the factor 0.6 will overestimate the methane formation
by at least the factor 2.4.The overestimation is probably even greater since the value of
BOD is determined in aerobic systems. The actual anaerobic degradation is normally lessthan BOD. This is due to both the fact that more compounds are aerobically degradable
than anaerobically, and to the presence of some oxygen, nitrate and sulphate in mostwastewaters.If the factor 0.6 kg CH4/kg BOD is used to calculate the estimated methane
formation from a certain amount of BOD this will lead to a great overestimation of
methane emissions. We hope we have misunderstood the use of the factor 0.6 kg CH4/kg
BOD. It is less embarrassing for us to be wrong, than it would be to have given totallywrong figures in the statistics.

Klara Westing

Rejected

The authors disagree that the default value for Bo is "totally unrealistic."
Although one might argue there is an overestimation of the maximum methane
generation capcitity (Bo in kg CH4/BOD) for some types of wastewater, it is areasonable approximation for domestic wastewater, which contains a highpercentage of biodegradable organic matter. In addition, the MCFs presented inthis chapter are derived as the product of (measured emissions) / (Bo) using thedefault value of Bo. Therefore, any change to the default Bo value would
trigger a need to reevaluate the default MCFs as well.

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Please make sure that the equations to be used for calculation of indirect emissions ofmethane due to disposal of treated waste water is covered by the general equation 6.1A,
or include a seperate equation for indirect emissions of methane. If you don't include aclear equation, you might open up room for misunderstanding (note people can be very
creative in misunderstanding things). In my interpretation, calculation of indirect
methane from effluent of WWTP should calculated as a separate pathway. Equation 6.1A
could be used, when TOWij refers to the TOW in the effluent of the waste water
treatment plant/septic tanks and S is considered zero.

Hans Oonk

Accepted withmodification

The emissions in question are no longer referred to as indirect emissions as in
the 2006 Guidelines to avoid confusion with indirect emissions of N2O from
deposition of nitrogen compounds. Direct emissions from discharge to aquatic
environments are now captured in the final draft version of the Refinement(Equation 6.1A) for all discharge pathways.

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For the effluent of WWTP I don't believe indirect emissions are a substantial source of
methane. Assuming TOW removal to be about 90%, and your MCF of 0,035, emissions
will be less than 10% of the emissions of the WWTP itself. Indirect emissions areimportant for e.g. septic tanks, where 50% of the TOW is discharged with the effluent.
Please make clear that indirect emissions should be calculated for all discharge pathways.

Hans Oonk

Accepted withmodification

The emissions in question are no longer referred to as indirect emissions as in
the 2006 Guidelines to avoid confusion with indirect emissions of N2O from
deposition of nitrogen compounds. Direct emissions from discharge to aquatic
environments are now captured in the final draft version of the Refinement(Equation 6.1A) for all discharge pathways.

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The MCF will be affected by oxic conditions. You mention some literature indicatingthat methane might be generated under oxic conditions. However under oxic conditions
MCF is unlikely to be as high as under anoxic conditions., due to competition of TOWremoval through other pathways (bacteriological aerobic degradation; consumption byhigher lifeforms as fish, worms, water fleas, etc.).

Hans Oonk

Noted

No action is requested from this comment. We already have a factor 6 times
higher when conditions are assumed to be more conducive to methanogenesis(benthic environments in lakes and reservoirs).

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Dishcarged BOD values are even lower for "new" processes such as the MBR process. It
usually generates discharged concentrations of BOD < 2 mg/L. This is also common inwell managed conventional activated sludge processes.

Klara Westing

Noted

No action is requested from this comment. The purpose of this test is to give
general guidance that BOD is typically present in treated wastewater effluents.
We cannot provide effluent BOD concentrations for every wastewater treatment
technology type. Additoinally, MBRs globally are very uncommon (total treatedwastewater volume in 2017 of ~12 GL/d; or ~4% of global sewered wastewater
volume), so this makes it less relevant to provide such specific guidance ingeneral introductory text.

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No arguments are given, why "well managed" and "not well managed" systems shallshow the same MCF-value. However, especially the O2-concentration in the waste waterstrongly influences methan generation.
The TOW (organics in the wastewater) does not reflect if a plant is overloaded. Maybein some cases the relation between TOW an Smass (organic component removed as
sludge) can give a hint of overloading.

Christoph Lampert

Accepted withmodification

If a plant is overloaded, the removal of organic material as sludge will be
reduced and should be reflected in the calculation of S in Equation 6.1 andSaerobic in Equation 6.3B. Therefore, compliers do NOT have to consider
different emission factors for well managed versus not well managed since theamount of organics removed from overloaded systems will be reduced and will
result in a higher amount of methane emissions compared to well managed
systems. The text was revised to elaborate on this topic.

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For "Treated waste water treatment system" the derivation of the MCF (0,028) from thestudies provided should be provided in the Annex. The number of literature provided for
the MCF is still very low. The results obtained in the small number of literature provided
show large differences.
The production of Methane strongly depends on the temperature. The MCF presented inTable 6.3 relate to which temperature of the waste water (compare text in line 426 and427 of the SOD)?

Christoph Lampert

Accepted withmodification

The literature clearly identify that there are methane emissions associated withcentralized aerobic treatment systems, and as such, it would be inappropriate toretain an emission factor of zero. An annex has been added to the document topresent the derivation of the revised emission factor.
Regarding the impact of temperature on methane emissions, the authors
acknowledge that there is an impact of temperature on the MCF. However,there is insufficient data to derive temperature-dependent default EFs. In
addition, reference documents rarely contain information on the temperature of
the system and the authors want to emphasize the fact that the MCF relateswith the temperature of the system and not with ambient temperature. In
WWTP, additional heat can be provided to optimise the treatment system and in
septic systems the tank is located in the ground and additional heat comes fromhot water used in the household.

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For emissions from on-site sludge treatment (AD, composting, burning) is referred tochapter 4 and 5. In these chapters, emissions are calculated as W * EF, where W is theamount of waste entering the treatment. My interpretation of the second order draft isthat emissions from sludge treatment should be calculated in a similar way as S*EF.
Following this approach, S has to refer to the amount of raw sludge, coming thetreatment ponds and entering the on-site sludge treatment, and not the amount ofstabilised sludge that leaves the perimeter of the WWTP. This should be properly
explained in the text, and the definition of S (line 357) should match this approach.

Hans Oonk

Accepted withmodification

The variable "S" in Equation 6.1 refers to the organic component within sludge
and has not been changed as suggested. The variable "Smass" in Equation 6.3B
refers to the mass of sludge produced from wastewater treatment. Table 6.12
provides Krem value also for sludge from various types of treatment systems.
The text has been updated to clarify this approach.

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For emissions from on-site sludge treatment (AD, composting, burning) is referred tochapter 4 and 5. Following this approach, emissions are calculated as S*EF, where S
refers to the amount of raw sludge, coming the treatment ponds and entering the on-site
sludge treatment. I think this is not a practical approach, since on a national scale nostatistics will be available of the amount of raw sludge produced by the WWTP. Only
stabilised sludge that leaves the perimeter will be recorded and reported. If you want tofollow this apporach, you need to include a conversion factor, that allows inventory
compilers to estimate raw sludge from stabilised and dried sludge as available fromstatistics.

Hans Oonk

Accepted withmodification

See response to Comment 3462.

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Hans Oonk

Accepted withmodification

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Most countries have no data on sludge generation from waste water treatment (the SOD
acknowledges this in line 609). Only few countries may have sludge removal data. Your
current aproach requires even more detail (amount of sludge removed per type of sludge
treatment). What guidance do you supply for countries, that don't have this information
available? I see three options: (i) you either allow them to neglegt S (in line with themethodology for N2O - see line 609); (ii) you encourage them to collect sludge data; (iii)
you provide a default sludge generation per unit of TOW removed. If the methodology
becomes dependent on availability of sludge generation data, guidance on methodology
used should also be included in the decision tree in figure 6.2.
For sludge treatment, you give EF for composting, anaerobic digestion and incineration.
However this overview is incomplete. Other sludge treatment options are: dewatering,
thickening, drying (gas engines exhaust), spread-drying. My preference would be tosimplify on-site sludge treatment and give seperate emission factors for (i) 'generalsludge treatment' (when no information available on type of sludge treatment), 'anaerobic
digestion' and 'other (non-anaerobic digestion)'.

Authors note

Hans Oonk

Noted

The refinement has guidance on estimating emissions from anaerobic
stabilisation. All other sludge treatment mentioned in the comment areconsidered to have negligible emissions - no emission factors.
Engines used in operating WWT plant or sludge management are not reported
under wastewater category.

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For emissions from sludge treatment, you propose to apply the defaults from the 2006
GL for biological treatment of solid waste. I think this is a major step back, for a few
reasons (i) these defaults are based on only few measurements and (ii) AD or compostingof solid waste is different from treatment of sludge. In line 113 in the SOD you state that
"The refinements [...] provide new and improved defaut values and emission factors [...]
based o further scientific research. For both composting and anaerobic digestion of solid
waste much more information has become available (see the overview by Oonk, 2017,attached). Specific for emissions from waste water treatment plants (including anaerobic
sludge digestion), recent emission measurements are performed by Daelmans, Delre andArs (the latter two PhD-theses are included in another comment of mine). Thesepublications do not directly give EF for sludge treatment, but can serve as a basis toquantify your EF.

Hans Oonk

Rejected

The calculation of emissions from sludge treatment should be consistent withthe calculation of emissions from similar processes not located at a wastewater
treatment plant; therefore, it is appropriate to reference the methodologies given
in other chapters.

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You propose to use the emission factors in chapter 4. However moisture content ofsludge and solid organic waste differs. So it makes a difference if you apply the emission
factors for wet waste or dry waste. Which ones do you propose to use.

Hans Oonk

Accepted

All values are based on dry mass of sludge; therefore, values for dry waste
should be used.

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In Table 6.3 in the SOD under anaerobic digestion of sludge, you indicate that CH4recovery is not considered here. Maybe I misunderstand what you mean by this. However
the default EF for anaerobic digestion in table 4.1 of the 2006 GL already accounts foralready account for CH4 recovery (see note uder table 4.1). The EF refers to net
emissions (difference between generation and recovery). Methane recovery is alreadyconsidered in the default value and emissions should not be corrected by subtracting
recovery once more.

Hans Oonk

Accepted

Text in table 6.3 changed.

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Under footnote 4) The publication of Kozak (Kozak, J.A., O’Connor, C., Granato, T.,
Kollias, L., Belluci, F. & Sturchio, N. (2009) Methane and nitrous oxide emissions fromwastewater treatment plant processes. In: Proceedings of the Water Environment
Federation, 1239 WEFTEC 2009, pp. 5347–5361) can not be found. It seems to be aconference publication and not a publication in e.g. a peer-reviewed journal. I personally
do not believe that 'peer-review' is sufficient quality criterion (lots of good research does
not make it to peer-reviewed publications, simply because they are performed by researchorganisation who do not focus on publication. And peer reviewed publications focus on
new methodologies. Once a method is accepted standardised, its results are not publishedin peer reviewed journals). However an article needs to be accessible in order to be able
to review it.

Hans Oonk

Accepted withmodification

The reference noted by the commenter is available online through the Water
Environment Federal or throughhttps://doi.org/10.2175/193864709793952530. The reference list has been
updated.

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There is no table 6.2. Does this mean that the table 6.2 in the 2006 Guidelines still
applies?

Hans Oonk

Accepted withmodification

Table 6.2 is still valid. The relevant portions of the 2006 methodology havebeen added to the 2019 Refinements document to make the guidance more clear
to the reader.

See response to Comment 3462.

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In the last year, two new PhD-theses are published on greenhouse gas emissions from
WWTP. Sébastien Ars and Antonio Delré (DTU, Denmark) performed measurements atseveral installations, using tracer-plume measurements. Delré included a review ofavailable measurements in his thesis and expressed emissions as EF (kg CH4 per kg
COD in the influent Table 1 page 11). His own measurements and the emission
measurements of Ars et al are not included in this overview. The best interpretation of
Delrés measurement is given in the supporting information of the article
https://doi.org/10.1016/j.scitotenv.2017.06.177 (for copyright reasons, I can not give
you this supporting information). Ars himself reports emissions and does not report EF.
The names of the WWTP are given and the actual load in the year of measurement canbe obtained. So the data from Ars can also be used to estimate EF. I took the effort andextracted the data from both theses in the spreadsheet attached.

Hans Oonk

Accepted withmodification

Additional peer-reviewed and published data sources, including Delre 2017 andNoyola 2018, among others were reviewed and Delre 2017 was accepted foruse in the development of the MCF for aerobic wastewater treatment systems.
The text and supporting annex have been updated accordingly.

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It appears that your MCF for WWTP is for a large part based on Daelmans, who
proposes exactly this EF of 0.007 kg methane per kg COD in the influent (so based on
TOW as activity data). However Daelmans proposed this value as an overall EF for all
activities of the WWTP (both the water ponds and the sludge-treatment) with COD in theinfluent as activity data (not TOW-S). Daelmans also concludes that most of theemissions are generated by sludge treatment, this value can not be used to justify an EF
for only the water ponds with (TOW-S) as activity. More in general, you need to realisethat emission measurements methods vary. Three types of measurements can be
distinguished: spot-measurements (using floating boxes); plume measurements and induct measurements. The scope (the parts of the WWTP from which emissions aremeasured) is different for these measurements. Spot measurements measure emissions
from the water ponds (not sludge treatment). Tracer-plume measurements (as used by
Ars and Delré) give plant-integral emssions (water ponds and sludge treatment), withsometimes an opportunity to identify the different sources on the site (through dispersion
modelling, when seperate plumes can be identified, see the PhD-thesis of Sebastien Ars).
In-duct measurements (Dealmans, STOWA) allow only measurements of emissions inventilated confined spaces and its scope depends on what unit operations are performedin such confined spaces.
Is it intentional that the same MCF values and EFs are listed for both 'Conventional
activated sludge (non-BNR) processes' and 'Biological nutrient removal (BNR)
processes'?

Hans Oonk

Accepted withmodification

The MCF for aerobic wastewater treatment systems is based on data collectedfrom 15 different plants, as documented in 8 different data sources. Therefore,
it is not accurate to say that the proposed MCF is based on Daelman. In
addition, the MCFs were developed from the measured methane emissions data
presented in the published literature, and taking into account the influent
organics (TOW) and the amount of organics removed in sludge (S), consistent
with the Tier 1 methodology proposed.

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The SOD guides countries to quantify emissions from the water ponds and sludge
treatment seperately. This only makes sense when this results in a more accuratequantification. I don't see the added value of this, compared to a simpler method
estimating emissions from water ponds and sludge treatment combined, using an overall
EF. If necessary you might distinguish between WWTP with anaerobic digestion ofsludge and WWTP without. The complications of quantifying emissions from sludge
treatment seperately are huge. To name a few (also addresed in individual comments): (i)most countries do not have data on sludge treatment available (you might provide default
sludge generation). (ii) If they have data available, it will be data on stabilised sludge
removed from the site and not sludge generated at the site (required as an input for the
methodology for emissions from biological treatment of solid waste in 4.1, that you
propose to use). So even when sludge data are available, a recalculation is required to getappropriate activity data. (iii) The EF for sludge treatment (chapter 4.1.) are outdated(based on few measurements) and measured for treatment of solid waste. Most emissions
are from post-treatment of solid waste digestate and this is different from post-treatmentof sludge-digestate. (iv) Recently more accurate emissin measurements are performed at
WWTP with and without anaerobic digestion of sludge. Both Daelman and Delré
proposes an overall EF for the total WWTP. The measurements might be used to
improve EF from sludge treatment, but you will need to make assumptions to do so. The
result will however be only an estimate of the actual EF for sludge treatment. So in
conclusion, I don't see added value in estimating emissions from water ponds and sludge
treatment seperately and large part of the problems mentioned might be solved bysimplifying the methodology, allowing the use of an overall emission factor for WWTP.

Regarding the various methods for measuring emissions, please note that only
data from plants where the wastewater emissions could be differentiated fromsludge digester emissions were used in developing the MCF.

Ole-Kenneth Nielsen

Rejected

Yes. Two rows are presented in this table to be consistent with the similar table
presenting N2O Efs. However, data were unavailable to differentiate Efs forthese two types of systems.

Hans Oonk

Noted

The key reason for guiding countries to quantify emissions from WW andsludge separately is that combined estimation has led to negative emissions
when countries have not properly estimated the methane generated by sludge.
This refinement stresses the need to estimate emissions by pathways (including
methane recovery, if any) to avoid this situation. If the methodology in Chapter
4 is used, estimation of emissions from anaerobic sludge treatment is simplified.

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This paragraph in the SOD gives guidance to quantify the amount of TOW removed as
sludge from the mass of sludge. I do miss the definition of sludge. From the context inthis paragraph it appears that Smass refers to the amount of sludge, removed from thewaste water treatment ponds, but before on-site treatment (composting, anaerobic
digestion). The definition of Smass in line 498 provides no clarity, since it simply reads'the amount of sludge removed from the waste water treatment'. Does it refer to raw
sludge (coming from primary/secondary treatment) before on-site post-treatment. Or
does it refer to stabilised sludge, leaving the perimeter of the WWTP?

Hans Oonk

Noted

It refers to raw sludge, and the text has been updated to reflect this. Table 6.12
allows recalculation of sludge (tons) to organics removed as sludge (BOD) for
various types of sludge (e.g. if data on sludge are based on anaerobicallystabilised sludge, Krem = 1). The definition of sludge is located in Section
2.3.2.

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Table 6.12 is not entirely clear. You need to keep in my the level of knowledge of people
performing an inventory. My understanding is: (i) first line: raw sludge primary
sedimentation refers to sedimentaion for WWTP with only primary treatment andsedimentation during primary treatment of more advanced WWTP. (ii) raw sludge fromseconday treatment: sludge removed from secondary treatment, after primary treatment.
(iii) the rest is obvious. My problem with the table is the following: line (ii) can bemisread as sludge from non-BNR

Hans Oonk

Accepted

Table 6.12 was changed and text clarified.

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Please check, whether the decision tree makes sense. As I read it now, when measured
COD-data are available, but no CS-EF, emission factors must be estimated, using areview of industry waste water treatment practices. I don't understand the lastrecommendation. What does it imply. Do you encourage countries to measure? And does
the recommendation also apply when the amount of COD treated is that large, the theindustrial waste water is no key category?

Hans Oonk

Accepted

We have revised the decision tree to clarify the three tiers related to emissions
from treatment and emissions from discharge. We have also clarified in the textthat countries that have COD or BOD measurement data (i.e., country-specificactivity data) may use a Tier 2 method.

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6

609

609

Even though only a few countries have sludge removal data, all countries have some kindof sludge removal. I therefore find the default value of zero too low, even though we alsofind it difficult to quantify a specific default value.

Klara Westing

Accepted

The new approach presented in this refinement is not based on default S=0.

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5

6

623

623

Third box at the left: 'Are measurements available'. This is not clear to me. Whatmeasurements do you refer to? Measurements of nitrous oxide emissions from individual
pathways? Or measurements of amount of N discharged via individual pathways? Somecountries have statistics available on N in the influent/effluent of all WWTP.

Hans Oonk

Accepted

Decesion tree has been revised to make it clear.

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6

719

720

It is said: "Bath and laundry water can be expected to contribute an additional 10% tonitrogen loadings as well." What is the source of this additional 10%? If it is e.g. skinflakes, than this would be allready included in the protein consumption.

Christoph Lampert

Accepted withmodification

More detailed explanation on the additional amount of nitrogen from householdproducts and the method of emission estimation was added to the text.

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723

724

Same comment as in our remarks on the FOD: Table 6.13: the logic is not clear. If a
default value of 0,85 for protein consumed is assumed (Line 717) the resulting TNDOM
differs depending on the Basis of Protein activity data:
e.g. activity data "protein available", in-sink disposal: 100 % protein * 1,1 = 110%e.g. activity data "protein consumed", in-sink disposal: 0,85 * 100 % protein * 1,25 =106%But even more important: How is it possible, that finally more than 100% of the protein
available ends up in the sewer system if there is no significant additional N-source in thehouseholds (in sink disposal). The same is true for Waste bin disposal: if the FAOSTAT
data includes the available amount of protein, how is it possible that 100% of this protein
ends up in the sewer system even some part of the protein is disposed of in waste bins
(again, there is no signifiicant additional N-source)?
The current equation 6.10 leads to a significant overestimation of the N-load in domestic
waste water!

Christoph Lampert

Accepted

The section was reformulated, parameters were simplified, and method ofemission estimation was adjusted. The data on protein available is related tofood contributions only, and does not account for nitrogen contributions fromother household products.

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742

742

Should NREM always be taken from Table 6.17, even if more country specific data isavailable? Please specify.

Klara Westing

Accepted withmodification

This is a general comment that applies to all default factors for Tier 1
methodology provided in the 2019 Refinement second order draft and some
additional guidance has now been added to the final draft to make clear that it isgood practice for countries to use the default factors provided for Tier 1
assessments, but where country-specific data and factors are available, this canbe used in higher order Tier 2 or Tier 3 assessments.

Comment ID Volume

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Authors note

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744

744

Table 6.17: in this new table the proposed default value for the N-removal for thetreatment type "secondary (biological)" shall be reconsidered, as the value of an N
removal of 40% is too high. Plants of this treatment type typically show an N-removal of
15-25%. This would mean, that also the lower value of the range on N-removal should be
adjusted. Higher N-removals (e.g. 40%) can occur if uncontrolled processes ofdenitrification takes place, but this is not the typical case for these plants.

Christoph Lampert

Rejected

The numbers in Table 6.17 are taken from a combination of international
literature as referenced in the table footnote and have also been cross-checkedby Lead Authors with real plant performance data from local national
wastewater treatment facilities. N removal rates for various secondary
wastewater treatment processes including extended aeration activated sludge,
lagoons, trickling filters and wetlands for Australian and New Zealand national
performance data from 243 wastewater treatment plants are in the range of 5590% (de Haas et al., 2018; https://doi.org/10.21139/wej.2018.023 ), so ourcurrent values for N removal in Table 6.17 are assumed valid.

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5

6

780

780

In New Figure 6.6, it might be a good idea to refer to Table 6.18 for examples ofindustries with large N2O emission potential.

Klara Westing

Accepted

A note is included in Figure 6.6.

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956

975

Amongst EU experts on waste, we had a discussion on the value of B0. I've beenrethinking this topic, and I think the real discussion is about the meaning of the word
'theoretically' in line 958. I agree with B0=0.25 for COD, when "theoretically" meansthat all COD is assumed to be biodegradable under anaerobic conditions. So nobiochemical limitations are assumed to exist and components, that are known to be notbiodegradable under anaerobic conditions (e.g. fibers, part of the bacterial biomass) arestill assumed to degrade. Under this definition B0 is something else than the'Biochemical methane potential' (BMP), which is the amount of methane generated froma sample under favourable, non-inhibited conditions. BMP excludes organic material,that does not biodegrade under anaerobic conditions. BMP can also be considered atheoretical methane potential, because in practice conversion of substrate to methanemight be hindered by low temperatures, lack of nutrients, product inhibition (e.g. VFA),
substrate morphology (larger substrates take more time to digest) and time. So B0 issomething else than BMP: B0 is the theoretical methane potential, neglecting limitations
to biodegradability of the substrate and BMP is the theoretical methane potential, taking
into account limitations to the biodegradability of the substrate. I think this has impact on
the guidelines: (i) I think this needs a bit more explanation in the text of Annex 6A.3, andyou might change line 958 into: "The maximum CH4 producing potential, assuming nobiochemical limitations exist for conversion of organic material into biogas, (B0) for
domestic wastewater" and you might add a sentence "Please note that B0 is not the sameas the biochemical methane potential (BMP), as determined in a lab-test, because BMP
does take limitations to the biodegradability of the substrate into account". (ii) This isvery important for the recommendation to develop CS-values of B0. It doesn't makemuch sense to develop a CS-value for B0, because it will be worldwide the same (organic
material might be described as cellulose and this degrades as mentioned in line 960). If
someone wants to improve B0, they have to determine the overal composition of TOW
in waste water (CxHyOzSaNb) and apply the Busswell equation to determine B0. They
should not base their CS-value of B0 on BMP-tests of waste water (because this will
result in about 50% of the value of B0). (iii) The values of Bo for industrial waste waterin New Table 6.14 are most likely based on BMP-tests and therefore somewhat lower
than the B0=0.25 kg/g COD.
It is mentioned that the BOD/COD ratio is 2.4. This is wrong, since it is the COD/BOD
ratio that is about 2.4. Throughout the text COD/BOD should be used instead of
BOD/COD.

Hans Oonk

Accepted withmodification

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973

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Annexes

2.24

2.28

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191

192

We accept the comments and have added a clarification in Annex A6.3 toemphasize that Bo is calculated considering total degradation of organic matter.
In addition, although one might argue there is an overestimation of the
maximum methane generation capcitity (Bo in kg CH4/BOD) of wastewater,
the emission factors presented in this chapter are derived as the product of(Bo)x(MCF) and the values of MCF are based on results of actual emission
measurements and the default value of Bo. Therefore, any change to the Bo
value would trigger a need to reevaluate the default MCFs as well.
Regarding the values on table 6.14, and upon further review of the data source,
we have determined these values represent emission factors for specific industry
wastewater treated in an anaerobic digester, and have removed them from thechapter.

Andrea Tilche

Accepted

These changes have been made to the text.

In Annex 2A.2 (New): There are some countries for which waste composition is not
given (e.g. Pakistan, Iran, Maldives), although there MSW generation and management
data are given in Annex 2A.1/updated. Is it due to lack of relevant data?

Muhammad Mohsin Iqbal

Noted

It is difficult to fiind waste compostion data from the mentioned countries.

"Unmanaged-deep (>5m waste）" in Table 3.1 (Updated) should be modified to"Unmanaged-deep(≧5m waste）" to reflect the annotation document No.6 in the table
3.1.

Ueda Hiroyuki

Rejected

This is to be in line with 2006 IPCC Guidelines.

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To lineComment

ExpertResponse233

Although N2O emission factor for gasification and melting (shaft furnace) in Japan's
NIR (GIO 2017) is 19.3 gN2O/t waste, quoted emission factor in the table 5.4A is "15.5
gN2O/kg waste". Further, although GIO 2017 provides N2O emission factors for
gasification fluidized bed type as 5.8 gN2O/t waste and gasification rotary type as 9.9
gN2O/t waste, these data are not quoted in the table 5.4A and much larger N2O emission
factors of 0.829 and 12.0 gN2O/kg waste are quoted instead. Rationale for thisintentional selection of N2O emission factors should be provided or values should be
revised.

Ueda Hiroyuki

Accepted

Authors note
We have updated our information in line with the reviewer's comment.