Life Cycle Assessment of a Domestic Wastewater Treatment Plant Simulated with Alternative Operational Designs

Round 1

Reviewer 1 Report

 

The authors present important and current issues. Every domestic wastewater treatment plants have impact on natural environment. The used by the authors tool permits chosen the best option in this aspect. In my opinion, a little correction should be made:

Line 186: It is: “the percentage of energy…” . It should be: “The percentage of energy…”

Figure 6. It is: “prposed alternatives”.  It should be: “proposed alternatives”.

Literature: 27, 32, 33 and 46 are not described properly.

Author Response

We appreciate your comments to improve our manuscript. All recommendations in report form and the comments for authors, have been integrated into the manuscript. The red text in the manuscript shows these modifications.

Response on the report form

	Yes	Can be improved	Must be improved	Not applicable
Are all the cited references relevant to the research?	( )	(x)	( )	( )
For empirical research, are the results clearly presented?	( )	(x)	( )	( )
Is the article adequately referenced?	( )	(x)	( )	( )

• The manuscript has been carefully revised, including the references and the presentation of results according to these recommendations and others raised by the reviewers, as can be seen in the revised version.

Response on the Comments and Suggestions for Authors

• Line 186: It is: “the percentage of energy…” . It should be: “The percentage of energy…” :

This modification was made.

• Figure 6. It is: “proposed alternatives”.  It should be: “proposed alternatives”. 

This modification was made.

• Literature: 27, 32, 33 and 46 are not described properly.

We reviewed all references formats, and we have made revisions accordingly.

 

 

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

1. The work is novel and exciting for readers, but the transition between the paragraphs in the introduction is stiff. Please summarize the similarities of the literature rather than simply list the work.

2. Please adjust the resolution or change the font size as some figures cannot be clearly displayed.

3. Please read the journal guide carefully and check that all references used are correctly written.

4. Grammatical errors must be corrected in the manuscript.

5. What is the main originality and novelty of this study? The author should manage to describe the novelty and show the knowledge gap.

6. The authors should follow uniform style while writing references (abbreviated or whole journal name).

Author Response

We appreciate your comments to improve our manuscript. All recommendations in report form and the comments for authors, have been integrated into the manuscript. The red text in the manuscript shows these modifications.

Response on the report form

	Yes	Can be improved	Must be improved	Not applicable
Are all the cited references relevant to the research?	( )	(x)	( )	( )
Are the research design, questions, hypotheses and methods clearly stated?	( )	(x)	( )	( )
Are the arguments and discussion of findings coherent, balanced and compelling?	( )	(x)	( )	( )
For empirical research, are the results clearly presented?	( )	( )	(x)	( )
Is the article adequately referenced?	( )	(x)	( )	( )
Are the conclusions thoroughly supported by the results presented in the article or referenced in secondary literature?	( )	(x)	( )	( )

• The manuscript has been carefully revised, including the clarity, references, the presentation of results, and the conclusion according to these recommendations and others raised by the reviewers, as can be seen in the revised version.

Response on Comments and Suggestions for Authors

1. The work is novel and exciting for readers, but the transition between the paragraphs in the introduction is stiff. Please summarize the similarities of the literature rather than simply list the work.

The introduction section has been modified accordingly, as can be seen in the revised version.

2. Please adjust the resolution or change the font size as some figures cannot be clearly displayed.

The figures' formats and font have been revised accordingly.

 

3. Please read the journal guide carefully and check that all references used are correctly written.

The references format has been checked, and the authors have made revisions accordingly.

4. Grammatical errors must be corrected in the manuscript.

The manuscript has been carefully revised and corrected when applicable.

5. What is the main originality and novelty of this study? The author should manage to describe the novelty and show the knowledge gap.

The clarity of the originality, knowledge gap, and novelty of this study has been improved, particularly in the introduction section, as can be seen in the revised version.

6. The authors should follow uniform style while writing references (abbreviated or whole journal name).

The references format has been checked and corrected as can be seen in the revised version.

 

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Last paragraph of Introduction section must
be enhanced and better clarify both intention
and outcomes of the performed study.

There is no quantified comparison in the
Conclusion section and this issue must be considered.

Author Response

Reviewer 3

We appreciate your comments to improve our manuscript. All recommendations in report form and the comments for authors, have been integrated into the manuscript. The red text in the manuscript shows these modifications.

Response on the report form

	Yes	Can be improved	Must be improved	Not applicable
Is the content succinctly described and contextualized with respect to previous and present theoretical background and empirical research (if applicable) on the topic?	( )	( )	(x)	( )
Are all the cited references relevant to the research?	( )	(x)	( )	( )
Are the research design, questions, hypotheses and methods clearly stated?	( )	( )	(x)	( )
Are the arguments and discussion of findings coherent, balanced and compelling?	( )	(x)	( )	( )
For empirical research, are the results clearly presented?	( )	(x)	( )	( )
Is the article adequately referenced?	(x)	( )	( )	( )
Are the conclusions thoroughly supported by the results presented in the article or referenced in secondary literature?	( )	(x)	( )	( )

• The manuscript has been carefully revised, including the clarity, references, the presentation of results, and the conclusion according to these recommendations and others raised by the reviewers, as can be seen in the revised version.

Response on Comments and Suggestions for Authors

• The last paragraph of the Introduction section must be enhanced and better clarify both intention and outcomes of the performed study.

The last paragraph of introduction has been revised and both the intention and outcomes of the study have been better clarified, as can be seen in the revised version.

• There is no quantified comparison in the Conclusion section and this issue must be considered.

The conclusion section has been revised to include a quantified comparison between the studied simulation scenarios, as can be seen in the revised version.

 

 

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments on Manuscript ID: sustainability-2315872

 

The study evaluates the environmental impacts of the Russtmiya wastewater treatment plant in Iraq and proposes three operational alternatives using LCA. Results show that activated sludge with a membrane bioreactor has the lowest energy consumption and moderate GHG emissions, while activated sludge with a slow sand filter has the best environmental performance due to its lower GHG emissions. Generally, the content of this paper is sufficient and very thorough and the objectives are clear. The results are also well discussed. Please address the following points:

 

1.     Line 37 – please correct the typographical error “WWT”.

2.     Line 47 – please correct the typographical error “us-er-friendliness”.

3.     Line 53 & 56 – please correct the citation format.

4.     Line 186 – please correct the sentence case (“T” in “the”).

5.     WWTP and WWTPs are interchangeably used. Any justification?

6.     Figure 1 can be improved. Don’t cramp the words in the image.

7.     Figure 2, 3, 4 and 5 – the resolution of these figures shall be improved, especially the sharpness of the wordings.

8.     Figure 6, 7, 8, 9 and 10 – the presentation of the graph shall be improved, especially the labelling of the axis, the format of the scale value. Please also add the unit for each axis.

9.     Mind the subscript and superscript.

10.  Please carefully go through the manuscript, make sure there is no typographical error.

 

More Comments:

The study evaluates the environmental impacts of the Russtmiya wastewater treatment plant in Iraq and proposes three operational alternatives using LCA. The research addresses the factors to be considered when designing a WWTP. The topic is relevant to the field in the sense that it applies the established methodologies to estimate the HGH emissions and energy use in the studied WWTP. The study also includes and compares three proposed frameworks namely 1) activated sludge with slow sand filters, 2) activated sludge with nitrogen removal and 3) activated sludge with membrane bioreactor for the assessment, hence providing added values to the subject area. Results show that activated sludge with a membrane bioreactor has the lowest energy consumption and moderate GHG emissions, while activated sludge with a slow sand filter has the best environmental performance due to its lower GHG emissions. Generally, the content of this paper is sufficient and very thorough, and the objectives are clear. The results are also well discussed. However, the figures shall be improved. The conclusions are consistent with the supporting data, and they successfully address the main objective. 

Author Response

Reviewer 4

We appreciate your comments to improve our manuscript. All recommendations in report form and the comments for authors, have been integrated into the manuscript. The red text in the manuscript shows these modifications.

For empirical research, are the results clearly presented?

( )

(x)

( )

( )

• The manuscript has been carefully revised, including the presentation of results, according to this recommendation and others raised by the reviewers, as can be seen in the revised version.

Response on Comments and Suggestions for Authors  

1. Line 37 – please correct the typographical error “WWT”.

This modification was made.

2. Line 47 – please correct the typographical error “us-er-friendliness”.

This modification was made.

3. Line 53 & 56 – please correct the citation format.

This modification was made.

4. Line 186 – please correct the sentence case (“T” in “the”).

This modification was made.

5. WWTP and WWTPs are interchangeably used. Any justification? WWTP.

This modification was made.

6. Figure 1 can be improved. Don’t cramp the words in the image.

Figure 1 was improved accordingly.

7. Figure 2, 3, 4 and 5 – the resolution of these figures shall be improved, especially the sharpness of the wordings.

The figures were revised accordingly.

8. Figure 6, 7, 8, 9 and 10 – the presentation of the graph shall be improved, especially the labelling of the axis, the format of the scale value. Please also add the unit for each axis.

The figures' formats, labels, and units have been revised accordingly, as can be seen in the revised version.

9. Mind the subscript and superscript.

All sub/superscripts have been checked and corrected when applicable, as can be seen in the revised version.

10. Please carefully go through the manuscript, make sure there is no typographical error. This typographical error was correct.
11. The study evaluates the environmental impacts of the Russtmiya wastewater treatment plant in Iraq and proposes three operational alternatives using LCA. The research addresses the factors to be considered when designing a WWTP. The topic is relevant to the field in the sense that it applies the established methodologies to estimate the HGH emissions and energy use in the studied WWTP. The study also includes and compares three proposed frameworks namely 1) activated sludge with slow sand filters, 2) activated sludge with nitrogen removal and 3) activated sludge with membrane bioreactor for the assessment, hence providing added values to the subject area. Results show that activated sludge with a membrane bioreactor has the lowest energy consumption and moderate GHG emissions, while activated sludge with a slow sand filter has the best environmental performance due to its lower GHG emissions. Generally, the content of this paper is sufficient and very thorough, and the objectives are clear. The results are also well discussed. However, the figures shall be improved. The conclusions are consistent with the supporting data, and they successfully address the main objective.

The figures have been improved as can be seen in the revised version.

 

 

Author Response File: Author Response.pdf

Reviewer 5 Report

Reviewer Comments to Author:

The manuscript is a research article type. Several changes and thorough revisions should be performed.

General drawback issues:

1. Language and grammar should be carefully revised in the whole manuscript.

2. Literature review is not enough; it needs more discussion.

3. Functional unit is not clear.

4. Database calculations based on carbon emission.

5. The X-axis for Figs. 6,7 should be the same symbols or the actual name of the cases.

6. Figure 1 is not expressed enough here. A figure can replace it to explain the workflow.

7. References: The authors should be cited some of the 2023 publications in the paper.

Author Response

Reviewer 5

We appreciate your comments to improve our manuscript. All recommendations in report form and the comments for authors, have been integrated into the manuscript. The red text in the manuscript shows these modifications.

	Yes	Can be improved	Must be improved	Not applicable
Are the research design, questions, hypotheses and methods clearly stated?	( )	(x)	( )	( )
For empirical research, are the results clearly presented?	( )	(x)	( )	( )
Is the article adequately referenced?	( )	(x)	( )	( )

• The manuscript has been carefully revised, including the presentation of results and the used references, according to this recommendation and others raised by the reviewers, as can be seen in the revised version.

Response on Comments and Suggestions for Authors  

1. Language and grammar should be carefully revised in the whole manuscript. 

The whole manuscript has been carefully revised and corrected, to eliminate grammatical mistakes.

2. Literature review is not enough; it needs more discussion.

The literature used has been revised and modified when needed to adequately meet the desire of this study, which is based on simulating a case study of full-scale wastewater treatment plant.

3. Functional units are not clear. 

The functional units used in the different analyses have been described adequately, also in the relevant figures.

4. Database calculations based on carbon emission.

The carbon emissions in this study have been estimated within the GPS-X software using Mantis3 model according to IPCC-2006 guidelines. A relevant statement has been included as can be seen in the revised version.

5. The X-axis for Figs. 6,7 should be the same symbols or the actual name of the cases.

The abbreviations used in X-axis have been modified accordingly, as can be seen in the revised version.

6. Figure 1 is not expressed enough here. A figure can replace it to explain the workflow.

Figure 1 was modified accordingly.

7. References: The authors should be cited some of the 2023 publications in the paper.

Relevant references from 2023. 

 

 

 

Author Response File: Author Response.pdf

Reviewer 6 Report

 

Review Report of Manuscript No. sustainability-2315872     

The manuscript entitled “Life Cycle Assessment of a Domestic Wastewater Treatment Plant simulated at different operational alternatives” is quite interesting. In totality, this paper is pleasant to read. However, it needs revision and there are some queries which the authors should kindly respond to make it good.

Some specific suggestions or questions are listed below:

1. The Abstract should be written more precisely and explain novelty of this work.

2. Line 33: WWTP.... Please check throughout the manuscript that abbreviations/acronyms are defined the first time they appear in each of three sections: the abstract; the main text; the first figure or table.

3. Introduction can be improved. Introduction should briefly place the study in a broad context and highlight why it is important. It should define the purpose of the work and its significance. The current state of the research field should be reviewed, and key publications cited. Finally, briefly mention the main aim of the work and highlight the principal conclusions. However, the novelty and significance of the manuscript were not highlighted in the Introduction section, please modify the introduction more clearly.

4. Line 69: [13, 18, 19, 20, 21; 22, 23, 24, 25, 26] please delete some citations.

5. Materials and Methods. Statistical analysis is very important. I suggest the authors add a new section in the Materials and Methods to describe the details of the statistical analysis.

6. Figure 2 should be improved. It’s not clear.

7. Line 147: CO2, correct the error.

8. Results and Discussion. The poor discussion of the results. Author just shows the great amount of results that they have achieved, but they did not use them to develop an interesting discussion which could supplement to earlier studies on Life Cycle Assessment models.

9. Conclusions: This section should be revised for the better understanding of the topic and its future research.

10. References: Many of the references have been superceded and more modern ones are required. In addition, please check the references carefully, some parts are missing.

 

 

Author Response

Reviewer 6

We appreciate your comments to improve our manuscript. All recommendations in report form and the comments for authors, have been integrated into the manuscript. The red text in the manuscript shows these modifications.

	Yes	Can be improved	Must be improved	Not applicable
Is the content succinctly described and contextualized with respect to previous and present theoretical background and empirical research (if applicable) on the topic?	( )	( )	(x)	( )
Are all the cited references relevant to the research?	( )	(x)	( )	( )
Are the research design, questions, hypotheses and methods clearly stated?	( )	(x)	( )	( )
Are the arguments and discussion of findings coherent, balanced and compelling?	( )	( )	(x)	( )
For empirical research, are the results clearly presented?	( )	(x)	( )	( )
Is the article adequately referenced?	( )	( )	(x)	( )
Are the conclusions thoroughly supported by the results presented in the article or referenced in secondary literature?	( )	(x)	( )	( )

• The manuscript has been carefully revised, including the relevant background and literature (when applicable), the methodology, the discussion and presentation of results and the used references, according to these recommendations and others raised by the reviewers, as can be seen in the revised version.

Response on Comments and Suggestions for Authors  

1. The Abstract should be written more precisely and explain novelty of this work.

The abstract has been revised accordingly as can be seen in the revised version.

2. Line 33: WWTP.... Please check throughout the manuscript that abbreviations/acronyms are defined the first time they appear in each of three sections: the abstract; the main text; the first figure or table

  This modification was made.

2. Introduction can be improved. Introduction should briefly place the study in a broad context and highlight why it is important. It should define the purpose of the work and its significance. The current state of the research field should be reviewed, and key publications cited. Finally, briefly mention the main aim of the work and highlight the principal conclusions. However, the novelty and significance of the manuscript were not highlighted in the Introduction section, please modify the introduction more clearly.

We have made revisions accordingly.

4. Line 69: [19, 20, 21; 22, 23, 24, 25, 26] please delete some citations.

This modification was made.

5. Materials and Methods. Statistical analysis is very important. I suggest the authors add a new section in the Materials and Methods to describe the details of the statistical analysis.

The statistical means used in this study are done within the simulation software GPS-X.

6. Figure 2 should be improved. It’s not clear. 

Figure 2 was improved.

7. Line 147: CO2, correct the error.

This modification was made.

8. Results and Discussion. The poor discussion of the results. Author just shows the great number of results that they have achieved, but they did not use them to develop an interesting discussion which could supplement to earlier studies on Life Cycle Assessment models.

The discussion of results has been improved as can be seen in the revised version.

9. Conclusions: This section should be revised for the better understanding of the topic and its future research.

 The conclusion section has been revised as can be seen in the revised version.

10. References: Many of the references have been superceded and more modern ones are required. In addition, please check the references carefully, some parts are missing.

The references have been updated and carefully revised as can be seen in the revised version.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 6 Report

The manuscript was rigorously evaluated by several reviewers, who provided contributions and the authors accepted the suggestions. The manuscript can be accepted for publication according to the revisions carried out.