Review Reports - Transition and Implementation of Circular Economy in Municipal Solid Waste Management System in Nigeria: A Systematic Review of the Literature

Round 1

Reviewer 1 Report

Dear Editors:

Thank you very much for the recommendation to review again the manuscript entitled " Transition and Implementation of Circular Economy in Municipal Solid Waste Management System in Nigerian: A Systematic Review of the Literature". I would like to send you my comments on it.

Revision

The study is a systematic review that addresses the issue of transition and Implementation of the circular economy in Municipal Solid Waste Management systems with a focus on Nigeria. However, the analysis of the total 23 articles reviewed only covers 10 from Nigeria, the rest from other developing countries; hence, the focus on Nigeria is very insipid; it should have been formulated for developing countries or Africa as a continent or region. Furthermore, the approach to Nigeria is very superficial, it does not analyse in question how the Circular Economy could be applied in the Municipal Solid Waste Management System. There is no development or analysis of the indicators of the circular economy and how this would contribute to its implementation in Nigeria, but only the theoretical content of the selected articles.

The authors argue that there are potential opportunities for the application of the circular economy by identifying the key indicators, enablers, barriers, and current practises of municipal solid waste management in Nigeria, but this outcome is not well developed in the results and discussion, where only two tables showing similar contents are presented and the presentation of the 23 selected articles becomes repetitive.

For this paper to be publishable in an academic quality journal, the presentation of the results needs to be restructured so that the articles reviewed are relevant to the argument of the study. In addition, aspects such as EC indicators, approaches, SWM elements, stakeholders, and technical, economic, and environmental aspects that reflect the potential of its implementation in the context of the country or region under analysis should be addressed. They even propose the application of reduction, recycling, and reuse (3R), when it is not deeply addressed in the document, but only argue for e-waste. Without considering these elements, it is very difficult to understand what the authors are proposing.

Some minor changes are suggested:

· The systematic review of the literature was conducted up to October 2022, it could have fully included the year 2022 (We are in June 2023).

· Bibliographical references should not be included in the conclusions.

Comments for author File: Comments.pdf

No comments

Author Response

Your professional input is well acknowledged, and your recommendations were received as a guide in ensuring that a quality paper is achieved for publication.

The table below presents the reply in sections, and pages based on the corrections so far made in line with your insightful comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

The research and language of the manuscript are well organized and structured, and the research significance is also quite important. However, the layout of the article is not good, and modifications are needed before considering publication in this journal.

1. The font in the tables is too large, so adjusting it reasonably

2. Adjust the structure of the flowchart more reasonably, without taking up so much space

3. The layout of the pie chart should be reconsidered, as the font is too small

4. The word in Figure 1 is too small, it is better to redraw it to incorporate the author's understanding, rather than simply citing one.

The language is quite good.

Author Response

Thank you so much for dedicating your time to reviewing the manuscript entitled " Transition and Implementation of Circular Economy in Municipal Solid Waste Management System in Nigeria: A Systematic Review of the Literature".
Your professional input is well acknowledged, and your recommendations were received as a guide in ensuring that a quality paper is achieved for publication.
The table below presents the reply in sections, and pages based on the corrections so far made in line with your insightful comments.

Author Response File: Author Response.pdf

Reviewer 3 Report

Introduction

1.1 Conceptual Background is the only subtitle in chapter 1.Introduction so it is not clear why it is used if there are no other subtitles.

Perhaps it can be omitted or another one can be added at the beginning, say 1.1 Solid waste management challenges in Nigeria, so the second is 1.2 Conceptual Background.

The introduction lacks a more detailed explanation of the issue of solid waste management (SWM) in Nigeria, which is the background for this research and the applied methodology.

At the beginning, the general issue of solid waste management (SWM) in modern society and the need to apply the concept of Circular Economy in Nigeria is presented. In addition, four main research questions to which the research should give an answer are clearly set.

At the end of this chapter, it should be briefly stated how the results of the study are transferred into the choice of strategy for the application of CE in Nigeria (approach, methodology, tools), and more specifically what the expected benefits are for Nigeria's natural environment security and socio-economic sustainability.

Methodology

As a methodology, the PRISMA protocol has been used.

An explanation is missing as to why this protocol was used and not another or some other methodology. What are the advantages and disadvantages of the used methodology? The use of this protocol-methodology should be justified through a shorter state of the art review.

The steps of the applied protocol are then explained through separate subsections: 2.1 Protocol and Registration; 2.2 Inclusion Criteria; 2.3 Sources and Search Strategy; 2.4 Study Selection and 2.5 Data Extraction.

From what was presented, it is not clear why someone would apply this procedure. No explanation is given as to why these steps are useful and how each of them, and how as a whole they help solve the problem and to what extent.

What else needs to be done to strengthen transition and implementation to CE?

It follows that the "Inclusion Criteria" are crucial for the success of the analysis and the results of the study, so they should be elaborated in more detail, as well as the connection between the criteria and objectives of the study. It was not presented how to select appropriate criteria related to problem issue. Examples of the application of the criteria used in other studies (literature) should be given, so that the differences and similarities from those used in this work can be assessed.

Results

Main results of literature review are presented: The outcome of the findings from the included 23 studies systematically reviewed is presented; 3.1 Location; 3.2 Themes; and 3.3 Method adapted. The results are clearly presented graphically.

It would be very useful if in this 3rd or next 4th chapter, based on literature data/reports, the general state of application of CE in developed countries (let's say one of them) with longer experience in application of CE in waste management would be presented. This would greatly help in assessing the situation in Nigeria in relation to the possible/desirable situation in the implementation of CE.

Discussion

This is a very important chapter of the work that evaluates the success of the project, so it must be elaborated in more detail. An explanation that better connects the findings in chapter 3 with the extracted information in chapter 4 (discussions) that should otherwise guide the development of CE in Nigeria is missing. How specific is the case of Nigeria compared to others and why?

The elaboration is quite general and insufficiently convincing to get the impression that the applied methodology is useful for the effort invested in the systematic review of the literature. It was not clearly stated what was useful, what was less and what was not useful in the applied procedure and how to improve it.

Indicators: Figure 4 should have the number 7. The units in the picture are not written.

Indicators of circular economy (CE) implementation in MSWM system in Nigerian are very modestly presented and commented. Namely, there is no explanation of the current situation in relation to the standard full list of indicators of CE for all types of MSW. Indicators, conditions and needs (production and consumption, waste management, secondary raw materials, and competitiveness and innovation) should be commented more systematically.

Enables: The key enablers/factors for the implementation of CE in MSWM system in Nigerian are not clearly specified. What exists for now and what should still be done? What are the main enablers of change in Nigeria (inspire, focus, enable, reinforce, and learn)? What or who can help in transition from LE to CE in Nigeria and why?

Barriers: What are the barriers impeding CE implementation in MSWM system in Nigeria? You wrote, barriers for transitioning from LE to CE are enormous. What are the barriers in Nigeria by affiliation/type and significance (financial, structural, operational, attitudinal, environmental, technological), then what is the list of barriers in order of importance for the implementation of CE, and what is the proposed order of removing the barriers, all in brief state clearly so that stakeholders can understand them.

Current practice: What is the current practice of waste management in Nigeria? Show more systematically the state of CE practices in Nigeria (sharing, leasing, reusing, repairing, refurbishing and recycling existing materials and products for as long as possible).

Conclusions

Citation of literature in Conclusions related to existing practices in countries, or technology CE is not acceptable. Current status and methodologies should be covered in the Introduction or Methodology chapters. Conclusions should clearly present whether the objectives of the research have been achieved, to what extent, what are the recommendations for continuing to solve the problem and/or supplementing the research results. Then it should be clearly stated briefly what is the good side and what are the shortcomings of the applied methodology and to what extent the used methodology can help.

It is necessary to emphasize more systematically and comprehensively the critical factors for promoting CE from the perspective of different actors in Nigeria and how waste management can contribute to the transition towards a CE. Namely, these are the main conclusions of the work.

Recommendations related to the conducted procedure "A systematic review of the literature" for Nigeria experts and stakeholders and international audience, are not clearly presented. The conclusion does not provide enough arguments for someone to apply the research concept presented in the paper.

Marketing of the approach and methodology used in solving the problem should be done more convincingly so that it is clearer how much it all pays off, to what level the problem is solved, i.e. at what stage of the solution and why, and how a strategy can be developed based on the results obtained, and action plan.

Author Response

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors improved the presentation of the results, the document is accepted

Author Response

Thank you for your insightful and instructive comments. The latest update has been done and the revised version of the manuscript has been updated.

Reviewer 2 Report

1. Page 10 is empty.

2. The page number has some mistakes, Pls check.

The language is OK

Author Response

Thank you for your insightful and instructive comments. The latest update has been done and the revised version of the manuscript has been updated specifically on the page numbering and blank page.