Assessing the Value of Ecosystem Services in Decentralized Sanitation Systems: A Case Study in a Vulnerable Mountain Area

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

BRIEF SUMMARY

I really enjoyed this work, as a reader. The authors present a very well-written and detailed work, which I believe is almost ready for publication in Sustainability journal, as they follow the main instructions and philosophy. In my review I present some questions and remarks, which I believe if the authors answer/follow, they could improve the quality of their article.

SPECIFIC COMMENTS

1. Lines 42, 55 etc: It is better to avoid to use words like “we”, “our”, “us” etc. Prefer a more general expression, f.e. replace “our linear economy” with “the linear economy” etc.
2. Lines 53-54: Write the references with their number, as you do for the rest text.
3. Line 151: It is important to present AQUANOVA with more details: When, who and where developed it…Comparison and advantages with other similar models…Did someone else use it in other studies or is this the first one?
4. Chapter 2 and Figure 1: Impressive separation system. How easy it to use it in every household? Which is the cost and how much space is needed? My biggest question, how do you succeed this separation? How does the system “realize” the path that each waste should be followed? Please add a small paragraph with these answers.
5. Table 3: What is (1), (2) etc. in formula and result column? Does it mean that these results are coming after the use of the relevant equations?
6. Conclusions: As it is a study with a lot of new information, I believe it is important to point the original parts that they were investigated in this review and why their work is important.

I would like to check the revised version

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The study explores how decentralized sanitation systems influence ecosystem service provision in fragile mountain environments. The focus is both pertinent and timely, given rising concerns about water quality, environmental health, and resilient infrastructure in vulnerable regions. The case study approach helps ground theoretical models in real-world complexity. In general, the study adds to existing knowledge in the fields of environmental science and sanitation engineering. Several aspects of the study require clarification and improvement before the manuscript can be considered for publication.

Some parts of the Materials and Methods are embedded within the Results. Moreover, referencing the Materials and Methods within the Results by inserting parenthesis numbers after each subsection is not appropriate for a scientific article. To improve clarity and structure, the Results should be clearly separated from the Methods.

L2–L3 The title would be clearer and more informative if it specified the location of the case study. For example, adding “Bosconero Hut in Northern Italy” would help readers immediately understand the geographical context.

L15 AQUANOVA can refer to different technologies (e.g., aerated wastewater treatment systems, compact purification equipment, or supercritical water oxidation processes). The authors should explicitly define which AQUANOVA system is being applied at the Bosconero Hut.

L163 Section 2, Case-study: AQUANOVA system at the Bosconero hut, would fit more appropriately under Materials and Methods rather than the Introduction, since it primarily describes the study site and technical system rather than framing the research background.

L205 The phrase ‘As it has been previously shown...’ shows that the information presented in Section 3.1 (Ecosystem services of AQUANOVA) Subsection extends from Section 2 (Case-study: AQUANOVA system at the Bosconero hut). The sections should be revised to ensure a clearer flow of information.

Comments on the Quality of English Language

The English could be improved to more clearly express the research.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript presents a valuable and timely case study on the economic valuation of ecosystem services provided by a decentralized sanitation system (AQUANOVA) in a vulnerable alpine setting. The topic aligns perfectly with the journal's scope, addressing circular economy, sustainable wastewater management, and biodiversity. The application of a mixed-method approach for ES valuation is appropriate, and the study has the potential to make a significant contribution to the field. However, the manuscript in its current form requires major revisions to strengthen the methodology, improve clarity, fully contextualize the results, and address several structural issues before it can be considered for publication.

 

• 1、The introduction is well-written. Please strengthen the link between the circular economy, biodiversity, and decentralized systems earlier in the introduction.
• 2、Several assumptions and data sources are not sufficiently justified or explained. Key parameters (e.g., biogas yield, carbon sequestration rate of plants) need more robust referencing or sensitivity analysis to ensure the validity of the economic calculations.
• 3、The rationale for choosing a 1% social discount rate needs stronger justification with citations, as it is a very low rate.
• 4、Discuss the potential for future research to quantify the non-valued services and to conduct a full cost-benefit analysis (including the high installation costs in mountainous areas) to assess true economic viability.
• 5、Some sentences are overly long and complex; consider breaking them down for improved readability.
• 6、Please carefully check all references for completeness (publisher, page numbers, etc.) and ensure they follow MDPI's formatting guidelines.
• 7、The Supplementary Material is frequently referenced but not available for review. All supporting calculations, data sources, and details must be submitted with the manuscript.
• 8、The detailed formulas presented here are repetitive with the Methods section. I recommend moving some detailed calculations to the Supplementary Material and keeping the Results section for presenting the final values, trends, and high-level comparisons. Would it be possible to present some of this data graphically?
• 9、It is recommended to optimize the details of Figure 1 below, including typography details, font sizes, and image clarity. It is recommended to check the formatting of formulas and tables in the article to ensure consistency.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

All comments have been addressed, and now the manuscript is in good shape. I recommend acceptance for publication.

Reviewer 3 Report

Comments and Suggestions for Authors

After careful revision, I recommend accepting this manuscript in its present form.