Relationship between GDP and Municipal Waste: Regional Disparities and Implication for Waste Management Policies
Round 1
Reviewer 1 Report
see attached
Comments for author File: 
Comments.pdf
no comments
Author Response
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Reviewer 2 Report
Based on the results of multiple regression analysis and the findings from municipal waste management data in Bulgaria, specific actions are proposed for municipal waste management in the country. Recommendations are made for developing sustainable waste management policies and sharing best practices between regions. Some comments given as follows:
1. Line 26, The novelty in the current article by the authors is too weak. The past has seen extensive published work of written material. It is required to provide more details for more explanation about the present novel in the introductory section.
2. Line 37, what is the basis for examinees EU-27?
3. Line 124, the economic growth trend recommended to provide in form of illustration.
4. Line 189, this section of explanation would be simplified with “Wanger and Weber”, do it with others too.
5. Line 217-232, it is suggested to explain in form of paragraph rather than poin-by-point.
6. Regarding waste management, recycle effort needs to explained, one of them would from: https://doi.org/10.12911/22998993/158564
7. Potential further study incorporating computational simulation needs to provided, it brings several advantages such as lower cost and faster results compared to experimental and analytical. For this purpose, provide the explanation along with relevant reference as follows: https://doi.org/10.3390/su142013413 and https://jurnaltribologi.mytribos.org/v33/JT-33-31-38.pdf
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Author Response
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Reviewer 3 Report
The presented manuscript “Relationship between GDP and Municipal Waste: Regional Disparities and Implication of for Waste Management Policies” discusses the relationship between GDP and Municipal Waste. The manuscript gives insight into the waste management policies which can be valuable information to the readers and researchers related to the areas. The manuscript has been presented well and written in good English. Before publication it requires some improvements. My specific comments are as follow:
1. The review compares the GDP per capita from European Union Countries. Is there any specific reason to choose only European Union Countries? There are several other developed countries which can serve as a role model for this study. In my opinion, the developing countries having less strict norms generate higher amounts of waste.
2. Page 5: Points 1 and 2 mention “incineration” and “composting”. Are these two terms synonymous? If not, it there meaning should be explained. In addition, their correlation should be described. Then only GDP can be correlated.
3. Figure 2: It contains several acronyms such as SE, NL etc. Each acronym should be expanded either in the figure legend or in the running text for better clarity.
4. Figure 4: the legend should be standalone describing what parameter is relevant to correlation coefficients.
5. Figure 5: what parameter is presented in X axis? It should be labelled with axis title with a unit of measure. What are the countries covered in lower, upper and high-income countries?
6. Figure 6: What are the values on X axis presents? It should be either written as axis title or should be explained in the figure legend.
Comments for author File: Comments.pdf
Author Response
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Round 2
Reviewer 1 Report
This manuscript has been improved relative to the original. There are though still issues with the organization and statistical analysis that need to be improved.
Organization: The cluster analysis should come before Fig 1. It helps alot to describe and defend groups of countries to compare. This would also help to reduce repetitive discussion that currently exists in text after Fig 1 and after Fig 2. Given the groupings, I do not believe that you can claim that the higher income countries generate more waste (e.g., L484-485). SE and NL generate less waste than many of the others. The text throughout this section needs to be more acurate in relating the findings with suitable interpretation
Statistics:
Multiple regression analysis. The results still do not provide enough statistical proof that all three independent variables are required. You need p-values (not F values) for the overall model AND each of the coefficients
Correlation analysis: Most of the text describing this analysis and Fig. 4 relates to trends over time. A correlation coefficient is NOT suitable for characterizing these trends. You need to do a regression analysis for both GDP and waste generation in order to support your interpretation. In the methods, you need to clarify that you used data for each year for that analysis, not the overall average.
Other comments
Methods:
define data sets first (L315-318) before the equations for the averages. The fact that you have 20+ years of data should be established first and that in some analyses you use these annual values (regression, correlation) and in others you use the average over that time period.
define "waste generation" In many countries - this includes waste sent to recycling. Are you include all waste generated regardless of fate, or are you only including waste that is sent to a landfill or incineration? It makes a huge difference relative to your later discussion about the value of improved recycling
Fig 1 - need a legend for color coding. This fig. only shows average over 20+years for each country. You cannot use it to establish trends over time (e.g., L461 "the increase is more gradual" for any of the individual countries.
Figure 2 - need better quality figure
Fig 3 - need a y-axis label. Error bars would help these results for upper middle and high income groups
Overall - this paper is trying to report trends and proactifes that have influenced those trends, although no time series analyses are included to support any of that discussion or conclusions.
no comment
Author Response
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Reviewer 3 Report
Suggested corrections have been made. But figures 5 and 6 are missing. So unable to verify the correction to them.
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Round 3
Reviewer 1 Report
The authors have made a lot of substative changes to increase the overall value and interpretation of their waste generation data set. One critical additions was in response to my request that they define what "waste generation" data includes. Based on their added text (L 290-291; 297, 298), my best interpretation is that their data sets include all waste that ends up in a landfill, incionerator ofr is recycled. If my interpretation is correct, then the next point is a major issue with this paper. If my interpretation is wrong, then this section needs to be clarified and you can ignore the next point.
If the waste generation data includes recycled materials, then all of the following interpretations that discuss efficient or sustainable waste management and the value of recycling programs. In this case, the amount of waste is not suitable indicator for rec=yclables or not and cannot be used to assess or describe efficient waste management. Examples of text where I was not conviniced that you had the right information to interpret: lines
375, 411, 434-437, 439-440, 490, 542, 601-605, 623, 627, 632-633, 637-639, 654, 685, 694, 709-712, 736,
(there are other places too, these are just examples)
L570-571 - there is not sufficient information to verify the thesis to show that there is a turning point in waste generation.
L793-818 - these conclusions have already been stated, you do not need to restate
There are some spelling errors introduced with the last round of edits:
L137 "resto"
L184 "countriesng"
L317 groping
In general, better to report p values rather than just p<0.05
needs to be more concise - though that is general writing, not necessarily english
Need to spell check
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Round 4
Reviewer 1 Report
The authors made minor changes in this revision. Their response t the previous comments addresses the main concern - but no changes were made to the manuscript. Overall, by including materials that were recycled in the definition, none of the quantitative analyses support the lengthy discussion about the role of recycling rates in the relationship between GDP and waste generation rates. Yet, the summaries of recycling initiatives for different countries are interesting and have their own value. The connection between the analysis work done and the related discussion still has some very weak point. I suggest these improvements before acceptance:
1. Make it explicitly clear that waste generation includes all waste that is sent to landfll, incineration and recycling. (L290-294)
2. Cut the discussion about the tipping point. The data in Fig. 3 and L568-570 do not offer any evidence that there is a tipping point for waste generation.
3. Put the discussion of recycling rates into its own section. This can be related to GDPs, but should notr integrate anything about total waste rates soince total waste generation does nmot provide any evidence about recycling
4. Add a short discussion of the limitations of this analysis that result from using total waste generation. This can include some of the points of defense that are incxluded in the latest reply to autrhors comments
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