Review Reports

Round 1

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

I reviewed the previous version submitted one month ago. The authors addressed the comments that I raised before.  I recommend this paper could be accepted.

Author Response

Thank you to the Reviewers for their overt praise of our manuscript. We are especially grateful for their time in reviewing our manuscript and their appreciation of its value.

Reviewer 2 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

Dear authors,
You have now significantly improved the original version. I would just like to inform you of a few details that you should correct for a final submission.
Figure 1: Here you have made a mistake when converting the data from Plastics Europe: The plastics production in EU 27 + 3 is not 38605, but 58605 kt.
Line 248: Your sentence (... dry entombment ...) suggests that a faster degradation of plastics can be achieved in a moist medium. The fact is, however, that components should never be degraded in a landfill, as methane, which is far more climate-relevant (compared to CO2), is formed under anaerobic conditions. For these reasons, the landfilling of organic waste will therefore be completely abolished in Europe.
Line 331: fibres instead of fibred
Lines 404 / 405 and Figure 8: You should avoid the term "ideal". What is also not clear to me is what is specific to Africa in this illustration, except for the illegally imported plastic waste. In my opinion, the point "energy recovery" should be expanded. It is not limited to incineration in cement factories, but can be extended to energy recovery in general. This point is not sufficiently addressed in your analysis. However, the use of plastics as a substitute fuel should be restricted to plants with adequate exhaust gas purification and by no means in households. Such regulations have long been in force in many European countries.
Lines 430 to 435: Here you give substitute fuels as an example, but primarily for waste containing cellulose and without specific restrictions. However, if textiles made from synthetic fibers are to be used for energy generation, their use must be restricted to large plants with high exhaust gas purification capacity, see the previous paragraph. The uncontrolled incineration of used textiles in households is apparently common practice in many developing countries and can lead to considerable damage to health.
Lines 472 / 473: The above also applies here.

Comments on the Quality of English Language

The overall linguistic quality is okay. However, there are some ambiguous formulations, so your manuscript should be checked again.

Author Response

Thank you to the Reviewers for their overt praise of our manuscript. We corrected the Figure 1 error, about line 248 considering your valuable critique we rephrased our sentence and corrected line 331. We corrected lines 404 / 405 according to your valuable suggestions. We try to give only possibilities of energy recovery use through examples without going deeper into details. We did the same for lines 430 to 435 and lines 472 / 473, and bring your suggestion in conclusion lines 501-503. We are especially grateful for their time in reviewing our manuscript and their appreciation of its value.

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

Line 34: a comma is needed after “is”

Line 52: better to say statement of the problem to presentation of the problem

Line 63: Please write the first statement in a present tense

Lines 63-69: The average plastic production rates of different regions have been expressed in kt, is it per a year, per a day, per dicade…..?

Lines 68-69: “Africa’s and the Middle East‘s production of plastic was 7%” As long as your review focuses on Africa, it is preferable to write Africa's share separately. Moreover, numbers are meaningless unless they are accompanied by sufficient units; what does 7% mean? World plastic production per year?

Figure 2. It is unknown which year the data in figure two refers to.

Line 86. What is the exact location of Egypt? It is Middle East or North Africa?

Lines 86-94: Under the subtopic 'Plastic production in Africa,' you discussed the current situation of the problem only in Egypt and to a lesser extent in Morocco; how do these data represent the problem in Africa as a whole (54 countries)?

Line 108. Figure 3. The year of production should be included in the caption, i.e. kt in which years? 

Line 119: replace the word ‘cheap’ with ‘cheapness’ and ‘which’ with ‘that’

Line 137-138: Did African nations import 172 Mt plastic waste or plastic materials between 1990 and 2017? There is huge difference in plastic waste and plastic material.

Lines 160-163: Please rewrite the statement so that it conveys meaning.

Line 163: it would be good if you explain how plastic contributes to sustainability

Line 184: Please add the word 'average' before the word 'data' in figure 4's caption.

Line 185: what is KPMG? When abbreviations appear for the first time in a text, please write them alongside their full name.

Line 197: Replace the phrase ‘as we will see later in Table 2.’ With ‘as it has been shown in Table 2’

Table 1: What does '2021' refer to in the first line of the second column?

Line 239: ‘In most African countries plastic waste is not orderly land-filling.’ Please provide a reference for this statement.

Line 245: please take the first statement to line 241.

Line 256 and 257: replace the word ‘smaller’ with ‘lower’

Table 3 would be good if it was changed to a three line table

Line 270: write the full name of LDPE and HDPE as they appeared for the first time in the text.

Line 280: I'm not comfortable with the phrase "to "dump" them there." If at all possible, please remove it.

Line 287: SHC, not SCH, must be used in the second statement.

Line 293: In the caption, what is the exception to *Kenya (2018) and **Madagascar? Can't you find the data for the aforementioned years?

Line 299: what is the importance of inserting a statement ‘South Africa is one of the biggest African economies’ here? It has no bearing on the previous or subsequent statements in the paragraph.

Line 460. I am certain that no African countries import "plastic waste."

 

Is it possible to draw any conclusions in the absence of sufficient updated data and studies on plastic exports and imports in Africa?

 

Comments on the Quality of English Language

The English language has an average level of quality. I recommend that the authors polish the paper with a good English language editor before resubmitting it for publication.

Author Response

Thank you for your valuable comments and suggestions. We review the manuscript again after your observations and make corrections to meet your suggestions. Correction of lines 34, 52, and 63 has been done. For lines 68-69, we mentioned the Middle East because our sources are giving the production quantity of both always together, and after, we considered Africa value alone (5%). For lines 86-94, considering already the beginning of the section ‘plastic production in Africa’ we try to find data in North, South, East, and West Africa to cover all parts of the continent, but it is not easy to find data of all African countries. In Figure 3, we added information to answer your observation. Lines 108 and 119 have been corrected. Your remark for lines 137-138 brings us to observe our error and make some corrections. Indeed, in the 27 years, Africa imported 172 million tonnes (Mt) plastic materials and polymers; and 230 Mt plastic product components. In lines 160-163, we try to meet your requirements and explain plastic sustainability. We corrected Lines 184, 185, 193, 239, 245, 256, 257, 270, 280, 287, Table 1, and meet your requirement for Table 3. We corrected the captions on line 293, the data for the aforementioned years for both countries are difficult to find, and we canceled on line 299 the mentioned statement. Concerning line 460, yes, we found some figures in the literature about plastic waste imports from African countries in line 152. Without updated data and studies on plastic imports and exports in Africa, it is difficult or even impossible to draw any accurate conclusions. The manuscript has also been checked and rephrased to improve the English expression. We actively considered the reviewer's request.

Reviewer 4 Report (New Reviewer)

Comments and Suggestions for Authors

The "Abstract" section needs to be refined and detailed according to the manuscript

In the text of the manuscript, highlight the scientific novelty of your manuscript separately, emphasize your scientific contribution

 

The topic of the manuscript does not correspond to a scientific manuscript, I recommend changing it to "Analysis of plastic use in Africa: environmental crisis"

In the Conclusions section, enter more detailed information (perhaps numbers), recommendations for stakeholders (perhaps an assessment of implementation risks). According to the topic, authors should specifically offer their opinions and recommendations to stakeholders. this section needs to be completely reformatted without references to the "references" section.

Author Response

Thank you to the reviewers for their overt praise of our manuscript. We are especially grateful for their time in reviewing our manuscript and their appreciation of its value. The interlinkage and co-dependence of the themes covered means that there will always be some degree of compromise in terms of the manuscript structure. We made some changes in the abstract to meet your request. Your suggestion to change our topic title to "Analysis of plastic use in Africa: environmental crisis" is difficult to implement now because it will be different from our initial concept and the time constraint is not adequate. We tried multiple different configurations and found that presented in the manuscript to work best.

Round 2

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

All the issues that I raised are resolved.

Author Response

Thank you to the Reviewers for their overt praise of our manuscript. We are especially grateful for their time reviewing our manuscript and their appreciation of its value.

Reviewer 4 Report (New Reviewer)

Comments and Suggestions for Authors

Dear authors! I think the "Conclusions" section needs to be reformatted, this section should give answers, not ask questions! Conclusions are your thoughts, results and recommendations!

Author Response

Thank you to the Reviewers for their overt praise of our manuscript. We solve the problem you mention concerning the conclusion by moving those points in the discussion. We are especially grateful for their time in reviewing our manuscript.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Massa and Archodoulaki reviewed the current status of plastic waste mismanagement in Africa. This study provides a very challenging topic to the community and policymakers around the world. I recommend some points should be addressed before the publication.

 

1.      The study should highlight that landfill technology could pollute the groundwater, which may lead to more water crises in drought areas in Africa.

 

2. The study should also highlight that incineration technology may produce tons of toxics air pollutants including dioxin, PAHs, etc. In addition, after-treatment for the incineration plants require a great amount of land and financial resource.

 

3.      The short-term policy for the local government is to restrict single-use plastics as soon as possible. 

Author Response

Thank you to the Reviewer for their valuable comments and suggestions. We are grateful for their time in reviewing our manuscript and their appreciation of its value. The manuscript has also been checked, rephrased in some part to improve the comprehension.

We have inserted sentences about landfill problem, incineration problem on page 13, and recommended on page 15 (conclusion section) the law enforcement of strict restriction of single-use plastic in the short-term for example. We've gone through the three important points you mentioned and found some references to implement these valuable suggestions.

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for submitting your research work to Sustainability. I appreciate the effort put forth by the authors. However, there are areas of concern that prevent me from recommending it for publication in Sustainability.

The structure and content of the paper resemble an essay more than a scientific research paper. It lacks rigor, parsimony, and objectivity. There are apparent theoretical and methodological issues. The paper seems to be positioned as a systematic literature review (SLR). If it is an SLR, the methodology section is missing. Clarification is needed on how the authors selected the papers for the review, the criteria used for selection, and the number of papers included. It would be beneficial to include a PRISMA flow diagram to illustrate the selection process. Additionally, the paper should emphasize its theoretical relevance, managerial implications, and policy recommendations.

Author Response

We reviewed over 300 articles using different key words as mentioned on page 2 to select 102 published documents which helped to realize this paper.

We restructured the manuscript, corrected and reworded some sentences, and added new references. The nature of the content, however, does not lend itself to a single obvious and superior structure. We made also the specified changes requested by the Reviewer.

The interlinkage and co-dependence of the themes covered means that there will always be some degree of compromise in terms of the manuscript structure. We did try multiple different configurations and found that presented in the manuscript to work best.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors,
You describe here a serious problem with global implications and I think it is good that you try to present the facts in the form of a scientific publication. I also see that it is difficult to get robust data especially from African countries specifically on the use and disposal of plastic waste.
However, for a review paper in a scientific journal, the appropriate standards must be applied and adhered to, regardless of the urgency of the problem presented.
However, this is precisely where a major weakness of your manuscript becomes apparent: It is not structured carefully enough, resulting in numerous repetitions. One finds the same or similar arguments in different chapters and the clarity suffers greatly. There is also a lack of clear diagrams for pictorial representation of the facts shown.
A possible structure could be:
a) Introduction with short (!) introduction to the problem.
b) Structured presentation of the problems, separated with subheadings or in separate subchapters, e.g. sorted by:
b 1) Production and import figures
- Production of plastics in Africa as a whole, then the most important countries listed individually, illustrated with two diagrams: a) World production, separated by continent, b) Production in Africa, separated by country.
- Imports of unprocessed plastics and plastics processed into products, sorted by country.
- Imports of finished products or packaging made from plastics
- Imports of plastic waste or "pseudo-products" that are de facto wastes.
c) Waste management in Africa in relation to other regions, e.g. Europe
- Recycling rates
- Energy recovery in large plants and on a small scale (e.g. use of used textiles as substitute fuel in the domestic sector)
- Orderly landfilling
- Irregular landfilling and other methods of irregular disposal (e.g., irregular incineration)
d) Special problem areas, stating quantitative facts where possible, possibly also naming particularly affected countries, e.g.
- Bags for drinking water supplies
- Imported used clothing
- Imported unambiguous plastic waste in the form of used packaging, defective electrical appliances, etc.
e) Successful approaches to combat the problems (e.g. Rwanda)
In all these points, you should first confine yourself to the facts. Consequences from these belong to the Discussion (f) and the Conclusions (g).
Some more specific points where you can see where comprehension problems arise:
Line 84: What do you mean by "units" here?
Lines 159 - 172: What is the reference to Africa here? I can find only one reference to this (47).
Lines 394 - 412: Actually only these lines should be your Conclusions.
A further remark: Your section on the possible contaminations of plastics should be shortened very much, because you can hardly name specific facts and many of the substances have disappeared from the market decades ago. Quite a few are also not plastic additives.
I wish you good luck with the revision and hope for an interesting and dedicated manuscript.

Comments on the Quality of English Language

Overall, the English is good and well understandable. In some cases, however, the logical order or grammatical reference is incorrect, so I would recommend correction by a native speaker.

Author Response

Thank you to the reviewer for his valuable comments and suggestions. We are especially grateful for their time in reviewing our manuscript and their appreciation of its value.

We restructured the manuscript, corrected and reworded some sentences, and added new references. We made also the specified changes and completely new restructured the manuscript following your valuable suggestion.

The interlinkage and co-dependence of the themes covered means that there will always be some degree of compromise in terms of the manuscript structure. We made also the specified changes and completely new restructured the manuscript following your valuable suggestion, considered your suggested section titles (all pages are concerned).

You are absolutely right; the new structure of the manuscript is much better.

Reviewer 4 Report

Comments and Suggestions for Authors

The topic covered by the authors is very interesting. However, the whole article seems a bit chaotic and ill-thought-out to me. The article also contains certain errors and shortcomings that should be taken into account before publication.

1. The Introduction seems a bit chaotic and not well thought out. There is different information in one paragraph; sometimes this information is also repeated. Sometimes the information contained in the Introduction applies to Africa, and sometimes to the whole world. In my opinion, this section requires thorough editing and tidying up.

2. The aim of the manuscript should be distinguished from the entire literature paragraph. Furthermore, it should be formulated more clearly. Is it really "The aim of this work is to increase the awareness of all stakeholders in plastic management"?

3. There is no clear indication of originality and novelty, and there is also no indication of the literature gap that the authors want to fill through their work.

4. Some information on the import, production and consumption of plastic in Africa can be found in the Introduction section, and some in section "2. Current plastic use /waste management in Africa" - please sort it out.

5. Why do the authors in Section 2 describe only selected African countries? What was the reason for this? No data? Please explain this.

6. Please ensure the stylistic and punctuation correctness of the entire text, and try to avoid repeating the same words or phrases in the same sentence or in subsequent sentences.

7. Please also take care of the editorial side, e.g. sometimes there are spaces between subsequent paragraphs and sometimes there are not. There are also some underlined words in the article. Is it necessary?

Author Response

Thank you to the Reviewer for their valuable comments and suggestions. The manuscript has also been checked, rephrased in some part, restructured to improve the comprehension, we restructured the introduction, formulated more clearly the aim of the manuscript on page 2, removed repetitions, gave the reason of the mentioning African countries in the study.

We corrected also punctuations, removed underlines of words on page 13, at the Reviewer's request. This also includes the specified changes requested by the Reviewer. Some new available data concerning plastic waste management in Africa have been highlighted in manuscript.

We added some references, and make sure that only one space between subsequent paragraphs. Errors can occur during the manuscript transmission because of instability in word format text.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

the paper has serious flaws even after revision. I stand with my previous decision.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors,
You received a number of instructions from me to improve the quality of your first manuscript. I considered this action to be absolutely necessary because the manuscript was not suitable for publication in any case.
You have now made some improvements, but the work as a whole is still not suitable for publication.
The current structure with its numerous deletions and shifts also makes it extremely difficult for a reviewer to read the manuscript. Some captions are missing (Figure 4), some images appear twice. Extensive deletions in the middle of a table lead in the same direction.
Some more specific points:
Lines 574 - 583 do not fit the heading "successful approaches..."
Lines 584 - 592: What were the results of the Rwanda measures? If there are no quantitative facts at all, the purpose of the publication is doubtful
Figure 8 is a somewhat confusing representation of a block diagram of processes and their consequences.
The entire Chapter 6 ("Discussion") is not a discussion, but a patchwork of opinions, facts, repetitions, etc.
The conclusions in chapter 7 are also very general and do not do justice to the subject matter.
I am sorry to say it, but unfortunately you did not manage to adequately implement the notes on your first manuscript. I therefore have great doubts that you will be able to deliver an appropriate manuscript in a further attempt.

Comments on the Quality of English Language

The language is difficult to understand in many places, and in some cases even misleading. The manuscript needs definitely a revision by an expert native speaker.

Reviewer 4 Report

Comments and Suggestions for Authors

The authors responded to my comments appropriately. I propose accepting the manuscript in its current form