Life Cycle Assessment Applied to End-of-Life Scenarios of Sargassum spp. for Application in Civil Construction
, João Adriano Rossignolo 2,*, LetÃcia Missiatto Gavioli 3, Camila Cassola Assunção Sposito 3, Fernando Gustavo Tonin 2, Mariana Matera Veras 4, Maria Júlia Bassan de Moraes 3 and Gabriela Pitolli Lyra 3Round 1
Reviewer 1 Report
The results of “Life Cycle Assessment applied to end-of-life scenarios of Sargassum spp. for application in civil construction” are of potential interest. The introduction section provides background of past literatures. However this section need to be improved a bit. In the result and discussion section, the results are elaborately discussed with figures. The conclusions are supported by the results. All the references are related to this research. However, the following corrections are to be carried out before the acceptance of the Manuscript.
1. Key words: Increase the number of keywords.
2. Introduction: Improve the introduction section by citing more literatures.
3. Mention the research gap of your work clearly.
4. Fig 14,16. Increase the font size, so that the readers will understand easily.
5. Compare your results with existing literatures.
6. Fig.7,8,9,10,11,13,17. What is Y axis indicates?
7. What is your recommendation/future scope of your research? Present it in the conclusion section.
8. Mention your research significance/impact in the manuscript.
Author Response
- Key words: Increase the number of keywords.
Response: The number of Keywords was increased, as transcribed bellow:
“Keywords: Life Cycle Assessment; LCA; Sargassum; Sargassum life cycle; Biomass life cycle, Sargassum end-of-life.”
- Introduction: Improve the introduction section by citing more literatures.
Response: The introduction and references have been revised.
- Mention the research gap of your work clearly.
Response: The research gap is stated in the last two paragraphs of introduction section, as transcribed bellow:
“In addition to the studies on the technical use of Sargassum biomass in construction products, it is very important to understand the possible environmental impact of Sargassum algae deposits and the possible mitigative potentials when used. However, quantitative data that allows for a robust environmental analysis, such as life cycle evaluation (LCA), were not found in recent literature.
Thus, this study aims to produce quantitative data for different end-of-life scenarios for Sargassum algae, focusing on potential applications of this macroalgae, in different forms, in the construction sector, by employing a sequential comparative LCA study.”
- Fig 14,16. Increase the font size, so that the readers will understand easily.
Response: Font size has been increased.
- Compare your results with existing literatures.
Response: There aren´t known similar research on the environmental impacts of sargassum end-of-life on literature. For this reason we developed sections 3.6 and 3.7 in the article, in order to compare the research results to known environmental impacts researched for other types of biomass, as sugarcane one.
- Fig.7,8,9,10,11,13,17. What is Y axis indicates?
Response: The Y axes on percentage scale indicate the relative contributions of each alternative/process for a given indicator. As different indicators have different metrics, a way to compare such contributions is putting it in a relative contributions graphic.
- What is your recommendation/future scope of your research? Present it in the conclusion section.
Response: The future scope of the present research is stated in the last paragraph of the Conclusions section, as transcribed bellow:
“In conclusion, the main objective of comparative analysis was achieved, since our study demonstrated the quantitative and qualitative environmental potential and feasibil-ity of the use of Sargassum biomass for particle and fly ash production. Thus, based on this feasibility analysis, studies can further investigate the potential for application of these materials in different products and components for civil construction, replacing the materials with a high environmental impact potential.”
- Mention your research significance/impact in the manuscript.
Response: We have added the contributions of the research at the final part of Conclusions section, as transcribed bellow:
“Thus, we emphasize that the main contribution of this work to the field of knowledge consists in verifying the environmental viability of processing Sargassum biomass for potential uses in several industries, with a special focus on the civil construction industry.”
Reviewer 2 Report
This original comparative case study research is based on the life cycle assessment approach (LCA). The study considered several end-of-life scenarios of the algae genus Sargassum. The study provided interesting findings to the "Sustainability" readers. However, there are certain areas to be improved before publication. Authors shall highlight the scenarios' environmental pros/cons (i.e., GHG emission reduction) compared to the baseline and provide essential information in the abstract. Moreover, the methods used to produce LCI have certain limitations. Authors need to discuss how these limitations affect the results.
1. Abstract: Better adding some numerical values or % reduction of GHG emissions etc, comparing the best scenario to the baseline scenario (the first part of the abstract is a long description. please make it short and replace it with the numerical outputs of the study in the abstract and conclusions).
2. Keywords: Rather than "Sargassum life cycle," better using "biomass" or a similar keyword.
3. Introduction: The introduction needs to be significantly improved. End-of-life uses of such material in end-of-life scenarios considered in this study must be added (global information). Also, what are the options did not consider in this study but reported in another place also can be added?
4. Revise figure 4: the process is "Energy/ fly ash production with Sargassum algae." However, the output is written as Sargassum Biomass.
5. Lines 210-211: "Thus, emissions were estimated by experimental determination of elemental..." This is not clear. Have you done an experimental study on elemental composition?
6. LCI: Provide all LCI data in a table format also (including the references etc.). See the supplementary document table S2 of this publication. https://www.mdpi.com/article/10.3390/su142114170/s1
7. How about NOx and VOCs emissions?
8. Figure 8: select colors properly to make the data clear and visible.
9. lines 568-572 and Figure 15: The text and figure data contradict. The authors need to discuss the results obtained first.
Author Response
- Extensive editing of English language and style required
Response: The article was submitted to a professional English reviewing process. Please, see the English Review Certificate attached to the presente submission.
- Moreover, the methods used to produce LCI have certain limitations. Authors need to discuss how these limitations affect the results.
Response: In this research, emissions computed at the end of life of Sargassum are limited to the different greenhouse gases, as described in the methodology. This limitation has now been highlighted in the Conclusions section, as transcribed bellow:
“As potential limitations of the research, we highlight the lack of data on the composition and end-of-life emissions of Sargassum. Faced with this gap, the present research has enabled the production of greenhouse gas emissions data, not considering, however, other emissions such as NOx and VOCs.”
- Abstract: Better adding some numerical values or % reduction of GHG emissions etc, comparing the best scenario to the baseline scenario (the first part of the abstract is a long description. please make it short and replace it with the numerical outputs of the study in the abstract and conclusions).
Response: Thanks for your comments. As suggested, the contextualization of the Abstract section was summarized, and quantitative data were inserted in order to make the abstract results more insightful.
- Keywords:Rather than "Sargassum life cycle," better using "biomass" or a similar keyword.
Response: Keywords were adequate, as transcribed bellow:
“Keywords: Life Cycle Assessment; LCA; Sargassum; Sargassum life cycle; Biomass life cycle, Sargassum Eend-of-life.”
- Introduction: The introduction needs to be significantly improved. End-of-life uses of such material in end-of-life scenarios considered in this study must be added (global information). Also, what are the options did not consider in this study but reported in another place also can be added?
Response: The introduction has been revised, however we do not have other works with similar analysis and comparison to compare, precisely this point is the originality of this article.
- Revise figure 4: the process is "Energy/ fly ash production with Sargassum algae." However, the output is written as SargassumBiomass.
Response: Thank you for your observation. The figure has been changed in the text and is now correct.
- Lines 210-211: "Thus, emissions were estimated by experimental determination of elemental..." This is not clear. Have you done an experimental study on elemental composition?
Response: To make the text clearer it was changed to:
“Thus, in the present study the emissions were determined in a semi-empirical way. Initially, the elemental composition of individual samples (S. flutans, S. natans I, and S. natans VII) collected in northeastern Brazil was experimentally determined. Next, the empirical formula of each species was calculated and Boyle's equation was applied to calculate the maximum theoretical emissions. The resulting values ​​were corrected by the degradability indices determined by Milledge et al. (2020) [27] for each species, considering the same index for all gases.”
- LCI: Provide all LCI data in a table format also (including the references etc.). See the supplementary document table S2 of this publication. https://www.mdpi.com/article/10.3390/su142114170/s1
Response: All theoretical greenhouse gas emissions found in this work, which consist of the primary inventory data for the different species of sargassum, are presented in Table 2 of the main article. All other marginal processes used in the inventory modeling used data from Ecoinvent 3.8, as described in the methodology section. Such data are being attached to this submission as Supplementary Material.
- How about NOx and VOCs emissions?
Response: The NOx and VOCs emissions could not be considered in the present study, due to the lack of data regarding such emissions in the literature, and in the Sargassum end-of-life emission process by the applied methods.
In this research, emissions computed at the end of life of Sargassum are limited to the different greenhouse gases, as described in the methodology. This limitation has now been highlighted in the Conclusions section, as transcribed bellow:
“As potential limitations of the research, we highlight the lack of data on the composition and end-of-life emissions of Sargassum. Faced with this gap, the present research has enabled the production of greenhouse gas emissions data, not considering, however, other emissions such as NOx and VOCs.”
- Figure 8: select colors properly to make the data clear and visible.
Response: Colors have been changed to make the graph clearer.
- lines 568-572 and Figure 15: The text and figure data contradict. The authors need to discuss the results obtained first.
Response: Thank you for your insightiful comment and careful observation. In fact, the aforementioned excerpt does not directly describe the results of the graph, but seeks to show how such absolute data can be relativized in different regional scopes, showing that, most likely, for a study carried out in regions of the center-south axis of the country, the impacts related to transport would be much more visible in the sargasso product process than in sugarcane bagasse.
Reviewer 3 Report
It is a good work, they present an integral vision of the problems that can arise in the final destination of the Sargasum biomass, currently a problem in several countries of the tropics.
However, they have a lot of information that lacks a deep discussion of results, especially in analysis of the causes of the different impacts in each method.
Author Response
It is a good work, they present an integral vision of the problems that can arise in the final destination of the Sargasum biomass, currently a problem in several countries of the tropics. However, they have a lot of information that lacks a deep discussion of results, especially in analysis of the causes of the different impacts in each method.
Response: Thanks for your comment. The article presents a large amount of quantitative results of potential impacts for the different proposed end-of-life scenarios, so the authors sought, throughout the entire section presenting the results, to discuss the main causes of the indicators that presented the greatest magnitude, in order to observe the main hotspots in the different processes of the product.
