Evaluation of the Sustainability of a Prototype for Atmospheric Ammonia Capture from Swine Farms Using Gas-Permeable Membrane Technology
, Leticia Chico-Santamarta 2, Ignacio Alonso Fernández-Coppel 3, Ernesto Gómez 4, Mercedes Sánchez-Bascones 4 and Luis Manuel Navas-Gracia 1,*Round 1
Reviewer 1 Report
The manuscript has relevance and is very important for livestock and procine farms, properly structured, although it is necessary:
include in the summary the main conclusion to which I arrive
In the introduction, despite carrying out a good description of the background on the subject under study, it is not clear why developing the study in pig farms
Author Response
Quality of English Language
Response for the reviewer: We reviewed the English language of the whole article as well as the style of the article. Necessary modifications were completed to the content of the article to improve the overall comprehension of the work described and evaluated.
Comments and Suggestions for Authors
The manuscript has relevance and is very important for livestock and procine farms, properly structured, although it is necessary:
include in the summary the main conclusion to which I arrive
Response for the reviewer: The abstract of the paper was completely modified in order to present a better explanation and reflection of the work included in the whole article, with the key sections summarized in the abstract, which includes the main conclusion achieved.
In the introduction, despite carrying out a good description of the background on the subject under study, it is not clear why developing the study in pig farms
Response for the reviewer: The authors agree on the comment provided by the reviewer, and for this reason, the introduction was modified not only to better describe the importance of doing this work in pig farms, but also, the overall background to reach the hypothesis of the work.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The article on ‚Evaluation of the sustainability of a prototype for Atmospheric Ammonia Capture from seine farms using Gas-Permeable Membrane Technology’ fits well within the scope or ‘agronomy’. Ammonia plays an important role in the production of fertilizers and negative environmental effects of agriculture on the environment. In the paper the LCA approach is used to quantify the effect of a new ammonia capture technology on 12 environmental impact categories.
However, the paper has several drawbacks which make it not acceptable for publication. There needs to be a lot of improvement to reach this aim.
1. Structure: the introduction is too much focussed on GHG emissions which is only one of 12 impact categories, in contrast the importance of ammonia emissions is not treated in enough detail and should be highlighted. In this context it should be explained in which way ammonia emissions affect the 12 impact categories chosen for the analysis. Overall the introduction is too long and is lacking the derivation of specific research questions and hypotheses. The results and discussion sections are below scientific standards as results remain unexplained – just figures and tables are compiled – and the discussion is just presenting results. What is absolutely missing is a critical discussion of the chosen LCA approach and the connected uncertainties, eventually also the system boundaries. It is also strange that slurry ammonia emissions are not considered in the calculations for both treatments which result in negative emissions for the RS treatment and all negative effects of the TS treatment are based on fertilizer production and transport – which is somewhat counter intuitive.
2. Critical discussion of methodology and connected uncertainties. Uncertainties should be given for all calculations. All impact categories need to be motivated in the introduction, treatment of system boundaries and how sources of impacted were considered should be revised.
3. Rather imprecise writing and problems in use of English language. Should be thoroughly revised.
L 18 ff check grammar of sentence
L 20 greenhouse gas (singular)
L 21 closed cycle – give short explanation
L 23ff please check grammar of the sentence
L 27ff reduction ‘of’ or reduction ‘by’? unclear for the whole remaining passage of the abstract.
L 41 Spain was the sixth largest/strongest emitter…
L 45 N2 Emissions? Rather N2O…
L 47 see above
L 47 please specify N application
L 49 manure application
This paper is mainly on ammonia emissions which is an indirect GHG, so the focus of the introduction on GHG is somewhat misleading.
L 51 ammonia is a nitrogen compound
L 52 of application of animal manures….
L 53 % emission of what?
L 54 there are no ammonia emissions from enteric fermentation as such
L 51ff I have the impression that there is a mixup of ammonia and GHG emissions in this section
L 60 I doubt whether gaseous emissions are the main source of nitrogen pollution in aquatic ecosystems. Here, surface runoff, interflow and leaching into the ground water are the main sources of N
L 64 in the form of ammonium…
L …pH of the medium.
L 67 no suggestion, it is a fact of physical chemistry
L 71 this sentence is not clear, in particular the very end
L 80 not in the slurry, in the faeces and urine
L 80 is bound to feed proteins??? Not clear what is intended here
L 82 surface waters
L 90 which reduce
L 92 the norm..
L 96 which can be used
L 110 ‘real’, by defining the system boundaries you always have a different system reality. ‘Real’ should be avoided here…
L 104 ff please show also the limitations and difficulties of LCA i.e. problems in identification of emission factors (often quite or even too simple) and availability of activity data
L 134 pig house
L 135 ff at the first development stage most factors used in the LCA are new and very uncertain, how to deal with this?
Research question quite unclear and hypotheses missing
L 149 ff not to compare the results but to show the effect of the new treatment.
L 158 goal and scope is introduction
L 210Tier 2 level
L 237 x no of places…
L 244 N2 emissions are connected with a particularly high level of uncertainty as they almost cannot be measured
L 305 and probably also because sulphur is a valuable nutrient
L 320 not necessarily, as the transport requirements depend on the specific density and N concentration of the fertilizer
Fig 5: please give also explanation of acronyms in the figure capture. A figure needs to be readable on its own
Results: text BY FAR too short, just presenting figures is not ok and below scientific standard
Discussion is mainly presentation of results
L 388 please indicate production source of ammonium sulfate, as there are huge differences between producers e.g. in Europe, Middle East, or Russia/Asia.
L 389 production rather than manufacture
L 413 per day
L 430 ff why should use of electricity result in PM 2.5 formation?
L 435ff why, ammonia is mainly emitted by the slurry?
L 471 ff why should the production of fertilizer have an effect on Land use?
Author Response
Quality of English Language
Response for the reviewer: We reviewed the English language and style of the article and made the necessary modifications to the content of the article to provide a more comprehensive paper and improve its explanation according to the observations made by the reviewer.
Comments and Suggestions for Authors
The article on ‚Evaluation of the sustainability of a prototype for Atmospheric Ammonia Capture from seine farms using Gas-Permeable Membrane Technology’ fits well within the scope or ‘agronomy’. Ammonia plays an important role in the production of fertilizers and negative environmental effects of agriculture on the environment. In the paper the LCA approach is used to quantify the effect of a new ammonia capture technology on 12 environmental impact categories.
However, the paper has several drawbacks which make it not acceptable for publication. There needs to be a lot of improvement to reach this aim.
- Structure: the introduction is too much focussed on GHG emissions which is only one of 12 impact categories, in contrast the importance of ammonia emissions is not treated in enough detail and should be highlighted. In this context it should be explained in which way ammonia emissions affect the 12 impact categories chosen for the analysis. Overall the introduction is too long and is lacking the derivation of specific research questions and hypotheses.
Response for the reviewer: The authors agree on the comment provided by the reviewer as we focussed the Introduction mainly to the Climate Change impact category, and truly, ammonia plays an important role in all of the other categories. Thus, to improve the work, we have not also changed most of the Introduction by adding information relevant to ammonia emissions and their importance, but also, we have re-written the abstract to reflect this point.
The results and discussion sections are below scientific standards as results remain unexplained – just figures and tables are compiled – and the discussion is just presenting results.
Response for the reviewer: The authors of this paper have followed the guidelines of this journal to present the work, which means that separate results and discussion sections are required. Thus, in the results section we limited ourselves to include purely the results achieved with the LCA simulation and their interpretation; on the other hand, in the discussion section we made the appropriate comments on the results obtained and expand the discussion based on the observations and literature review on the topic area.
“Research Manuscript Sections
Results: Provide a concise and precise description of the experimental results, their interpretation as well as the experimental conclusions that can be drawn.
Discussion: Authors should discuss the results and how they can be interpreted in perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible and limitations of the work highlighted. Future research directions may also be mentioned. This section may be combined with Results. “
What is absolutely missing is a critical discussion of the chosen LCA approach and the connected uncertainties, eventually also the system boundaries.
Response for the reviewer: The authors agree on the comment provided by the reviewer as there was a need of more critical discussion based on literature review on the topic compared with the results obtained. Thus, we have made significant changes in the discussion section to improve the readiness of the paper and the choices applied to the LCA have been explained in more detailed. Some specific clarifications that could help understand our work: The objective of the LCA was the evaluation of the prototype with GPM for NH3 capture, therefore the system boundaries are limited to the operation of the prototype in the pig houses; considering that the prototype produces ammonium sulfate that can be used as fertilizer, the synthetic fertilizer equivalent to ammonium sulfate and its transport to the same point of application was established as a reference scenario.
It is also strange that slurry ammonia emissions are not considered in the calculations for both treatments which result in negative emissions for the RS treatment and all negative effects of the TS treatment are based on fertilizer production and transport – which is somewhat counter intuitive.
Response for the reviewer: The slurry is excluded from the system boundaries, and thus, its emissions were not considered in the final analysis,(however, if we consider the emissions coming from the manure (slurry) while it is inside the shed, according to the calculations explained in paragraph 2.2) only the air that is captured from the pig houses was considered. In fact, when considering the emissions in the two scenarios, the reference scenario has a higher environmental load due to the ammonia that is not captured and is emitted into the atmosphere.
There are no negative emissions; what happens is that when the ammonia is captured, the emissions are reduced, which would normally be emitted if the prototype were not implemented. On the other hand, we analyzed processes in the reference scenario that, although they are not equivalent to those evaluated in the treatment scenario, are those that would be eliminated if only the treatment alternative were used.
- Critical discussion of methodology and connected uncertainties. Uncertainties should be given for all calculations. All impact categories need to be motivated in the introduction, treatment of system boundaries and how sources of impacted were considered should be revised.
Response for the reviewer: According to the reviewer's comment, the discussion section was modified and the methodology used, the results obtained, and the uncertainties associated with the LCA were discussed more critically. Also, as previously mentioned, the introduction was modified and the choices made for the LCA inventory were described.
- Rather imprecise writing and problems in use of English language. Should be thoroughly revised.
Response for the reviewer: The use of English was reviewed completely.
L 18 ff check grammar of sentence
Response for the reviewer: Corrected
L 20 greenhouse gas (singular)
Response for the reviewer: Corrected
L 21 closed cycle – give short explanation:
Response for the reviewer: Corrected
“a closed cycle (i.e. birth, breeding, transition and fattening take place on the same site)”
L 23ff please check grammar of the sentence
Response for the reviewer: Corrected
“Two scenarios were studied: a reference scenario in which there was no NH3 reduction from the air captured in the sheds and one treatment scenario that used the GPM technology.”
L 27ff reduction ‘of’ or reduction ‘by’? unclear for the whole remaining passage of the abstract.
Response for the reviewer: Corrected - Reduction of… Because the reduction in the impact indicator score is being quantified in terms of its unit of measurement.
L 41 Spain was the sixth largest/strongest emitter…
Response for the reviewer: Spain was the largest emitter, However, this part was eliminated in the modifications.
L 45 N2 Emissions? Rather N2O…
Response for the reviewer: They are indeed N2O emissions.
L 47 see above
Response for the reviewer: They are indeed N2O emissions.
L 47 please specify N application
Response for the reviewer: They are indeed N2O emissions.
L 49 manure application
Response for the reviewer: In agreement… Manure application
This paper is mainly on ammonia emissions which is an indirect GHG, so the focus of the introduction on GHG is somewhat misleading.
Response for the reviewer: The introduction was modified to focus a bit more on ammonia emissions; however, as the sustainability assessment considers GHG emissions, they are also taken into account due to their close relationship with climate change.
L 51 ammonia is a nitrogen compound
Response for the reviewer: Exactly, it was modified in accordance with the comment alluding to nitrogen compounds with emphasis on ammonia.
L 52 of application of animal manures….
Response for the reviewer: Corrected … of application of animal manures
L 53 % emission of what?
Response for the reviewer: Greenhouse gas emissions
L 54 there are no ammonia emissions from enteric fermentation as such
Response for the reviewer: Revised
L 51ff I have the impression that there is a mixup of ammonia and GHG emissions in this section
Response for the reviewer: It has been modified to explain better the relevance of ammonia as a pollutant and the relation of the problems generated with respect to the impact category indicators of the methodology used.
L 60 I doubt whether gaseous emissions are the main source of nitrogen pollution in aquatic ecosystems. Here, surface runoff, interflow and leaching into the ground water are the main sources of N
Response for the reviewer: Indeed, gaseous emissions are not the main source of nitrogen pollution, but slurry is a considerable source of ammonia production, which is emitted in different forms and states, polluting different media, in the case of gas reacting with acidic species.
L 64 in the form of ammonium…
Response for the reviewer: In the form of ammonium
L …pH of the medium.
Response for the reviewer: pH of the medium
L 67 no suggestion, it is a fact of physical chemistry
Response for the reviewer: Corrected
L 71 this sentence is not clear, in particular the very end
Response for the reviewer: Corrected
L 80 not in the slurry, in the faeces and urine
Response for the reviewer: Corrected
L 80 is bound to feed proteins??? Not clear what is intended here
Response for the reviewer: Corrected
L 82 surface waters
Response for the reviewer: Corrected
L 90 which reduce
Response for the reviewer: Corrected
L 92 the norm.
Response for the reviewer: Corrected
L 96 which can be used
Response for the reviewer: Corrected
L 110 ‘real’, by defining the system boundaries you always have a different system reality. ‘Real’ should be avoided here…
Response for the reviewer: Corrected
L 104 ff please show also the limitations and difficulties of LCA i.e. problems in identification of emission factors (often quite or even too simple) and availability of activity data
Response for the reviewer: The information used in the LCA was based on primary information obtained from the operation of the prototype on the farm and was complemented with calculations and information from databases. Its sources are explained in the document.
L 134 pig house
Response for the reviewer: Corrected
L 135 ff at the first development stage most factors used in the LCA are new and very uncertain, how to deal with this?
Response for the reviewer: Corrected, It was explained how the uncertainties in the data used for the LCA were reduced.
L 149 ff not to compare the results but to show the effect of the new treatment.
Response for the reviewer: The reference scenario is used as a baseline to show the effect of using GPM technology on a pig farm.
L 158 goal and scope is introduction
Response for the reviewer: This section defines the objective and scope of the LCA.
L 210Tier 2 level
Response for the reviewer: Corrected
L 237 x no of places…
Response for the reviewer: Corrected
L 244 N2 emissions are connected with a particularly high level of uncertainty as they almost cannot be measured
Response for the reviewer: Agree, emissions were "estimated" because they cannot be precisely calculated.
L 305 and probably also because sulphur is a valuable nutrient
Response for the reviewer: In agreement
L 320 not necessarily, as the transport requirements depend on the specific density and N concentration of the fertilizer
Response for the reviewer: Agree, however, in this work we assumed the closest marketing point for the purchase of synthetic fertilizer.
Fig 5: please give also explanation of acronyms in the figure capture. A figure needs to be readable on its own
Response for the reviewer: Corrected
Results: text BY FAR too short, just presenting figures is not ok and below scientific standard. Discussion is mainly presentation of results
Response for the reviewer: Results section shows the results and makes a brief description of the most relevant ones, the discussion section expands its description a little more and seek to discuss them.
L 388 please indicate production source of ammonium sulfate, as there are huge differences between producers e.g. in Europe, Middle East, or Russia/Asia.
Response for the reviewer: For the modeling, the Ammonium sulfate, as N {RoW}| ammonium sulfate production | APOS, S process was taken from the Ecoinvent 3.6 database, the selection was made taking into account that the data was intended to be from a complete production process of a fertilizer with the same conditions as the commercial obtained at the closest point to the farm and the data with respect to the location were not up to date.
L 389 production rather than manufacture
Response for the reviewer: Corrected
L 413 per day
Response for the reviewer: Corrected
L 430 ff why should use of electricity result in PM 2.5 formation?
Response for the reviewer: Due to the electricity production systems, the electricity mix
L 435ff why, ammonia is mainly emitted by the slurry?
Response for the reviewer: Indeed, in swine housing, ammonia is mainly produced by slurry.
L 471 ff why should the production of fertilizer have an effect on Land use?
Response for the reviewer: The industrial production of fertilizers requires equipment in the factories that requires changing the use of the soil, which is what this indicator associates.
Author Response File: Author Response.docx
