15 Years After the National Solid Waste Policy in the City of São Paulo: Timid Advances in Recycling

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. The manuscriptused a "longitudinal case study" to analyze the recycling data from 2006 to 2024, but the entire text mainly used descriptive statistics and did not conduct statistical tests on time series changes.
2. The manuscriptrepeatedly attributes changes in recovery rates to the establishment of "governance transition," "institutional restructuring," and "SP Regula," but currently lacks sufficient evidence to prove a causal relationship between them. Suggest adding quantitative analysis.
3. The author mentions that the data sources come from AMLURB and SP Regula respectively, and points out that "the reliability and comparability of historical data" may be affected by institutional adjustments. However, the article did not discuss the potential errors that this factor may bring and its impact on long-term trends.
4. Figure 4, Figure 5, and Figure 6: It is recommended to add corresponding statistical information to not only display but also support statistical inference.
5. The discussion mainly revolves around São Paulo, with relatively insufficient comparison with similar international cities. Suggest adding comparisons with municipal solid waste management or recycling systems in international major cities such as Tokyo, Seoul, Shanghai, and Singapore.
6. The manuscriptuses strong policy statements such as "environmental justice", "selective geography of collection", and "structural barriers". Although it has certain theoretical significance, there is currently a lack of sufficient quantitative analysis support.

Author Response

Thank you for your valuables comments and suggestions.

1. The manuscriptused a "longitudinal case study" to analyze the recycling data from 2006 to 2024, but the entire text mainly used descriptive statistics and did not conduct statistical tests on time series changes.

Reply: We have included statistical tests on time series changes, as described in Methods (Pages 5, 6, and 7)

• 2. The manuscriptrepeatedly attributes changes in recovery rates to the estThankablishment of "governance transition," "institutional restructuring," and "SP Regula," but currently lacks sufficient evidence to prove a causal relationship between them. Suggest adding quantitative analysis.
• Reply: We have added quantitative analysis to verify the effect of governance transition, and, in fact, found no evidence of a causal effect. We have changed the text regarding this issue. It is highlighted in page 8.
•  
• 3.The author mentions that the data sources come from AMLURB and SP Regula respectively, and points out that "the reliability and comparability of historical data" may be affected by institutional adjustments. However, the article did not discuss the potential errors that this factor may bring and its impact on long-term trends.

Reply: This phrase was taken out of the article, as there was no evidence of potential errors in data on long-term trends.

4. Figure 4, Figure 5, and Figure 6: It is recommended to add corresponding statistical information to not only display but also support statistical inference.

Reply: Statistical information was included in the results section, pages 7 and 8.

5. The discussion mainly revolves around São Paulo, with relatively insufficient comparison with similar international cities. Suggest adding comparisons with municipal solid waste management or recycling systems in international major cities such as Tokyo, Seoul, Shanghai, and Singapore.

Reply: In the discussion, we have added references from other international cities as Bogotá, Capetown, San Francisco and cities in England and Wales. We have not included cities from Asia, as we have no previous studies in this area, and the short time to make required changes in the article turned it difficult to attend this suggestion.

6.The manuscriptuses strong policy statements such as "environmental justice", "selective geography of collection", and "structural barriers". Although it has certain theoretical significance, there is currently a lack of sufficient quantitative analysis support.

Reply:We have changed statements for inequalities or difference, instead.

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript presents a longitudinal assessment of household solid waste recycling in São Paulo between 2006 and 2024, examining the implementation of Brazil's National Solid Waste Policy and comparing observed outcomes with the targets established in the Municipal Integrated Solid Waste Management Plan. The topic is relevant and the use of nearly two decades of official municipal data represents a valuable empirical contribution.

However, the manuscript currently reads more like a comprehensive technical report prepared for municipal planning than as an international scientific article. While the dataset is valuable, the scientific novelty, analytical depth, and international framing require substantial strengthening before publication.

After addressing the aspects enlisted below, the paper has potential because it documents long-term implementation of waste management policies in one of the world's largest metropolitan areas.

Overall, the manuscript is written primarily for readers familiar with Brazilian waste policy. To improve international relevance, I would suggest the following research question: what lessons from São Paulo are transferable to other cities?

1. Title could be more concise
2. Abstract reads as overly long, with no novelty element being highlighted- authors are advised to explicitly state why this study differs from previous evaluations. Also, several numerical values are unnecessarily precise.
3. Within the keywords, I would suggest the replacement of the term “public works” with environmental governance or other more appropriate terms
4. In the Introduction section there is an extensive portion that describes local organization of waste collection systems that have little relevance for international readers. The motivation of the study as well as the research gap that is intended to fill is not highlighted. The Introduction section needs organization in terms of length (around 30% of the introduction may be reduced without affecting the comprehensibility of the paper) and in terms of information provided. Authors are advised to replace descriptive administrative information with a stronger literature review.

The novelty features of the paper should be disclosed by the end of this section. The contribution of the authors that would be in my opinion: assembling a long-term municipal dataset, evaluating implementation of public policy, documenting persistent socio-spatial inequalities are useful but need to be explained much more explicitly.

5. In Materials and Methods Section there are several methodological aspects that need to be addressed. Firstly a better organization in order to distinguish between: primary data collection, indicator calculation, statistical analysis, spatial analysis. Currently the spatial analysis is insufficiently explained and no statistical analyses are described. The description of literature searching is superficial. In my opinion, the methodological transparency must improve.
6. Regarding the Results section, the data themselves are valuable and the comparison with MISWMP targets is arguably the manuscript's strongest contribution, however in the current version the interpretation frequently replaces objective reporting. The associations between governance changes and recycling performance are not statistically evaluated. Authors are advised to include trend analysis, confidence intervals, simple regression, correlation analysis, non-parametric trend tests. These additions would substantially improve scientific rigor without requiring new data.

Figures numbers should be revised.

The Spatial Analysis topic is interesting but underdeveloped. The manuscript visually compares recycling and inequality. However, no formal spatial statistics are presented. To improve the quality of the data analysis such as Pearson correlation, Spearman correlation, or geographically weighted regression would considerably strengthen this section.

7. The Discussion section needs substantial improvement. Currently, it mostly repeats the Results. There is a very limited comparison with international studies. The authors should discuss experiences from states in the area at least such as: Colombia, Chile Mexico (with similar mega cities and associated solid waste management problems) to demonstrate broader relevance. The Discussion should also identify transferable lessons for other metropolitan areas.
8. Conclusion section should be reworked around: principal findings, implications, limitations, future research. That would be preferable than introducing additional policy recommendations.

Comments on the Quality of English Language

Professional English editing is essential.

Author Response

Thank you for your valuable comments and suggestions to improve the manuscript.

This manuscript presents a longitudinal assessment of household solid waste recycling in São Paulo between 2006 and 2024, examining the implementation of Brazil's National Solid Waste Policy and comparing observed outcomes with the targets established in the Municipal Integrated Solid Waste Management Plan. The topic is relevant and the use of nearly two decades of official municipal data represents a valuable empirical contribution.

However, the manuscript currently reads more like a comprehensive technical report prepared for municipal planning than as an international scientific article. While the dataset is valuable, the scientific novelty, analytical depth, and international framing require substantial strengthening before publication.

Thank you for recognizing the valuable empirical contribution.

We have pointed the scientific novelty of the manuscript which is the intra-urban differences, improved the analytical depth by including statistical analysis, and including an international framing with scientific references to Bogotá, Capetown, San Francisco and England and Wales.

After addressing the aspects enlisted below, the paper has potential because it documents long-term implementation of waste management policies in one of the world's largest metropolitan areas.

Overall, the manuscript is written primarily for readers familiar with Brazilian waste policy. To improve international relevance, I would suggest the following research question: what lessons from São Paulo are transferable to other cities?

We have included some information Brazilian situation regarding solid waste management on page 15 to inform readers not familiar with Brazilian waste policy.

In the conclusions we point out to a few lessons from São Paulo.

1. Title could be more concise.   Reply: We have turned the title more concise.
2. Abstract reads as overly long, with no novelty element being highlighted- authors are advised to explicitly state why this study differs from previous evaluations. Also, several numerical values are unnecessarily precise.     Reply:    We have shortened the abstract and stated why this study differs from previous ones. We also took out most of the numerical values form the abstract.
3. Within the keywords, I would suggest the replacement of the term “public works” with environmental governance or other more appropriate terms.    Reply:   We have replaced the keyword.
4. In the Introduction section there is an extensive portion that describes local organization of waste collection systems that have little relevance for international readers. The motivation of the study as well as the research gap that is intended to fill is not highlighted. The Introduction section needs organization in terms of length (around 30% of the introduction may be reduced without affecting the comprehensibility of the paper) and in terms of information provided. Authors are advised to replace descriptive administrative information with a stronger literature review.  Reply:  We have accepted the suggestions, reducing the length by 30% and introduced the novelty of the study in page 1.

The novelty features of the paper should be disclosed by the end of this section. The contribution of the authors that would be in my opinion: assembling a long-term municipal dataset, evaluating implementation of public policy, documenting persistent socio-spatial inequalities are useful but need to be explained much more explicitly.

5. In Materials and Methods Section there are several methodological aspects that need to be addressed. Firstly a better organization in order to distinguish between: primary data collection, indicator calculation, statistical analysis, spatial analysis. Currently the spatial analysis is insufficiently explained and no statistical analyses are described. The description of literature searching is superficial. In my opinion, the methodological transparency must improve.     Reply:  The section was re-written with description of primary data collection, method used for indicator calculation, and statistical and spatial analysis used. We also included an appendix with data on recycling for the 19  years from all the regional administrations.
6. Regarding the Results section, the data themselves are valuable and the comparison with MISWMP targets is arguably the manuscript's strongest contribution, however in the current version the interpretation frequently replaces objective reporting. The associations between governance changes and recycling performance are not statistically evaluated. Authors are advised to include trend analysis, confidence intervals, simple regression, correlation analysis, non-parametric trend tests. These additions would substantially improve scientific rigor without requiring new data.   Reply: -We thank you very much for the remarks. In fact, after statistical analysis, we found that governance changed did not affect recycling rates performance, which has persistent growing rates. We have changed the text to reflect this information.

Figures numbers should be revised.  - We have revised the figures' numbers. Thank you for pointing this error.

The Spatial Analysis topic is interesting but underdeveloped. The manuscript visually compares recycling and inequality. However, no formal spatial statistics are presented. To improve the quality of the data analysis such as Pearson correlation, Spearman correlation, or geographically weighted regression would considerably strengthen this section.    - We have included correlation analysis in the paper. it did strengthen this section, as a direct correlation was found between lower recycling rates and social inequalities levels. 

7. The Discussion section needs substantial improvement. Currently, it mostly repeats the Results. There is a very limited comparison with international studies. The authors should discuss experiences from states in the area at least such as: Colombia, Chile Mexico (with similar mega cities and associated solid waste management problems) to demonstrate broader relevance. The Discussion should also identify transferable lessons for other metropolitan areas.    Reply:- We have taken out from the discussion the repeated results and did some comparison with international studies. However, it was impossible to do more exhaustive international research because of time limitation for the review. We are motivated to do next article with international experiences, after doing further research on them.
8. Conclusion section should be reworked around: principal findings, implications, limitations, future research. That would be preferable than introducing additional policy recommendations.  Reply - We have re-worked the conclusions and included your important suggestions.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for the author's response. The reviewer believes that the manuscript can be accepted.

Author Response

Thank you very much for your important suggestions which helped us to improve the paper.

We are very glad of the approval.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have successfully addressed several important concerns by strengthening the methodological framework, incorporating appropriate statistical analyses, clarifying the novelty of the study, and expanding the discussion with comparisons to international experiences. The manuscript now provides a convincing long-term assessment of recycling performance in São Paulo while highlighting the persistent role of socio-spatial inequalities in shaping waste management outcomes. Given the importance of the dataset, the long observation period (2006–2024), and the policy relevance of the findings, I consider the manuscript suitable for publication after minor revision.

1. The reworked abstract is more focused and informative. The aspect that could be improved concerns the broader significance of the work. The concluding sentence could move beyond describing São Paulo and briefly indicate why these findings are relevant for waste governance in other metropolitan areas or in middle-income countries
2. The Introduction section has improved in coherence and the research gap is identified. However, there is still a considerable portion is dedicated to describing the Brazilian legislative framework in detail. While these legal instruments are clearly relevant, the description is too detailed. I would suggest a modest reduction in legislative detail, allowing greater emphasis on the scientific questions addressed by the paper and on the conceptual relationship between governance, socio-spatial inequality and recycling performance.
3. The Results section is clear, logically organized and substantially stronger than in the previous submission. However, minor improvements can be made. At several points, the Results section moves beyond presenting observations and begins interpreting the underlying causes of the observed patterns. In my opinion, some of these explanatory statements would fit within the Discussion section, where they could be examined alongside the international literature.
4. The Discussion is now well developed and provides an effective interpretation of the empirical findings. Occasionally, some of the sections become somewhat normative, presenting specific policy proposals with a level of certainty that exceeds the direct evidence generated by the study. While these recommendations are reasonable, they could be presented more explicitly as possible policy directions rather than as direct conclusions arising from the statistical analyses.

Comments on the Quality of English Language

The manuscript is generally well written, and the quality of the English has improved substantially compared with the previous version. Only minor language editing is recommended to improve fluency, sentence structure, and consistency in scientific style. 

Author Response

The authors have successfully addressed several important concerns by strengthening the methodological framework, incorporating appropriate statistical analyses, clarifying the novelty of the study, and expanding the discussion with comparisons to international experiences. The manuscript now provides a convincing long-term assessment of recycling performance in São Paulo while highlighting the persistent role of socio-spatial inequalities in shaping waste management outcomes. Given the importance of the dataset, the long observation period (2006–2024), and the policy relevance of the findings, I consider the manuscript suitable for publication after minor revision.

 

Thank you for you valuable comments which enriched our paper.

1. The reworked abstract is more focused and informative. The aspect that could be improved concerns the broader significance of the work. The concluding sentence could move beyond describing São Paulo and briefly indicate why these findings are relevant for waste governance in other metropolitan areas or in middle-income countries

We have included this information in the abstract.

1. The Introduction section has improved in coherence and the research gap is identified. However, there is still a considerable portion is dedicated to describing the Brazilian legislative framework in detail. While these legal instruments are clearly relevant, the description is too detailed. I would suggest a modest reduction in legislative detail, allowing greater emphasis on the scientific questions addressed by the paper and on the conceptual relationship between governance, socio-spatial inequality and recycling performance.

We have reduced the Brazilian legislative framework to lines 68 to 73.

1. The Results section is clear, logically organized and substantially stronger than in the previous submission. However, minor improvements can be made. At several points, the Results section moves beyond presenting observations and begins interpreting the underlying causes of the observed patterns. In my opinion, some of these explanatory statements would fit within the Discussion section, where they could be examined alongside the international literature.

We have taken the explanatory statements and put them at the discussion section lines 456 to 466.

1. The Discussion is now well developed and provides an effective interpretation of the empirical findings. Occasionally, some of the sections become somewhat normative, presenting specific policy proposals with a level of certainty that exceeds the direct evidence generated by the study. While these recommendations are reasonable, they could be presented more explicitly as possible policy directions rather than as direct conclusions arising from the statistical analyses.

We have made changes in the language to present recommendations as policy directions and only when conclusions derived from our empirical findings.   Comments on the Quality of English Language

The manuscript is generally well written, and the quality of the English has improved substantially compared with the previous version. Only minor language editing is recommended to improve fluency, sentence structure, and consistency in scientific style. 

We have done minor language editing and hope the fluency is improved.