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Peer-Review Record

Identifying Hub Wastewater Propagation Chains in China’s National Economic System: A Model Coupled Input-Output Analysis with Graphical Theory

Water 2021, 13(17), 2351;
by 1,2 and 1,2,3,*
Reviewer 1: Marlous Blankesteijn
Reviewer 2: Anonymous
Water 2021, 13(17), 2351;
Received: 1 August 2021 / Revised: 24 August 2021 / Accepted: 25 August 2021 / Published: 27 August 2021

Round 1

Reviewer 1 Report

The paper highlights the importance of waste water reduction and uses a particular method (APL) to attribute the extent to which sectors burden waste water treatment systems in china. It is well written and well documented. Especially section in which methods are explained could use more explanation. The coupling between the models does not become fully clear. The graphs provide interesting insights in the nodes  between sectors at which policy interventions could help to reduce the amount of waste water produced and how these streams are handled.


R 155-162

Provide more info on the method for splitting. Quite fundamental for the study therefore needs more explanation.


R 356-357

Future wastewater reduction policies may be conducted based 356

on HWPCs to reduce direct and embodied wastewater discharge of the entire economic 357

system. > please make more concrete what type of policy interventions could be made based on this study.


R 368

strengthen technological innovations in the full process of produc- 368

tion and wastewater treatment .. which technological innovations could be strengthened?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors have worked to address my comments on the previous version, and have added more explanations of their methods.  Most of my comments on the original manuscript have not been adequately addressed, however.  For example, the objectives of the work are not clearly presented, Figures 1-4 are still not well explained, and there remain significant problems with English language usage.  For publication in an English language journal, the manuscript should be edited by a native English speaker before it is resubmitted.   

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report


The authors have improved the manuscript through explicit presentation of objectives, improved English language usage in the manuscript (some problems remain, as indicated below), and better linkage of the conclusions to the analyses conducted in the work.  Below I suggest some additional modifications to strengthen the manuscript.  



1.  Abstract, line 28:  In the statement "It outperforms WPCs ...", the meaning of "It" is not clear.  Replace "It" with "The APL-HCG model".  Also, insert "APL" after "traditional".  In line 29, insert "model" after "APL-HCG"

2. Page 2, lines 40-41:  Change "The sewage sludge with rapidly growing quantities" to "Rapidly growing quantities of sewage sludge"

3. Page 2, line 43:  delete "available"

4. Page 2, line 46:  change "well-directed" to "focused"

5. Page 2, lines 59-60:  change "the wastewater discharge" to "wastewater discharges"

6. Page 2, line 61:  Change "the wastewater discharge" to "wastewater discharges"

7. Page 2, line 62:  change "the wastewater discharge" to "wastewater discharges"

8. Page 2, line 67:  make "source" and "discharge" plural by adding "s" to the end of each

9. Page 2, line 68:  change "responsibilities to reduce it" to "responsibility to reduce them"

10. Page 2, line 72: change "it has the potentials to simulate" to "such measurements have the potential to enable simulation of"

11. Page 3, line 118: change "aims" to "aimed".  Page 3, line 121: change "intends to utilize" to "utilized."  Past tense is appropriate, as the work is completed

12. Page 3, line 122:  change "traditional model" to "the traditional APL model"

13.  Page 3, lines 123-136:  These statements are summary and conclusions statements and don't belong in the Introduction.  I recommend moving these lines to the beginning of the Conclusions section.  Page 3, line 123:  delete "Therefore," and begin with "We proposed ..."   Page 3, line 127:  change "aforementioned traditional" to "traditional APL"

14. Page 4, line 167:  change "traditional model" to "the traditional APL model"

15. Page 10, line 329:  insert "APL" before "model"

16. Page 11, line 372:  delete "have some basis in"

17. Page 11, lines 377-380:  As given in Comment 13, I recommend moving the text cited there from the Introduction and merging it with the first two sentences of the Conclusions.

18. Page 11, lines 380-389:  Delete "Based on the sequential IOO tables." Begin a new paragraph with "The proposed APL-HGC model ..."  Put the sentences in this section into past tense; the work is completed.

19.  Page 13, line 433:  insert "APL" before "model"



Author Response

Thank you for your comments. We have made modifications to these points. See the manuscript marked red in acceptance mode or the “Track Changes” function in revision mode.

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

The article is rather hard to understand. From my own opinion, although the concept of “Wastewater propagation chains” was unique, it is unclear what does it mean. The raw data in this study was not clearly presented. Also, the input-occupancy-output analysis presented in this study seemed contradict with the input-output graphical model. The reference style in this study was not coherent. Overall, the purpose and implications of this study seemed to be unclear, which need to be clarified.

Reviewer 2 Report

The study presents the identifications of hub wastewater propagation chains in China by a new coupled input-output graphical model. It also outperforms wastewater propagation chains identified by the traditional model and the scenario to sample equal sector number as the hub wastewater propagation chains randomly. The research presents a rather complete study of the subject and is recommended to be accepted without changes.The study presents the identifications of hub wastewater propagation chains in China by a new coupled input-output graphical model. It also outperforms wastewater propagation chains identified by the traditional model and the scenario to sample equal sector number as the hub wastewater propagation chains randomly. The research presents a rather complete study of the subject and is recommended to be accepted without changes.

Reviewer 3 Report


The authors describe the development of an input-output graphical model to evaluate "wastewater propagation chains" in China, but there is not sufficient background and explanation provided about the methods employed and there is insufficient explanation of the results obtained to be able to understand the work presented in the manuscript.  Further, the English language usage in the manuscript has many problems, adding to the difficulty of understanding the work presented.  I sense that the authors have completed some novel analyses that may be potentially useful in relation to system-level understanding of wastewater generation in China, but the present manuscript enables only the most approximate understanding of the work completed by the authors.  I cannot recommend this manuscript for publication.  Below I provide specifics about some of the problems with the manuscript, as well as some suggestions for improving the manuscript, though a complete re-working of the manuscript will be needed.



  1. The urgency and importance of the work are over-stated.  In the Abstract on Lines 13-14, for example, it is stated that understanding of wastewater propagation chains is "urgently needed."  On lines 55-56 of the Introduction it is stated that it is "extremely important" that wastewater propagation chains be studied.  In the Abstract and Introduction the authors do not  explain clearly what is meant by "wastewater propagation chains", and certainly do not make a convincing case that understanding them is "urgently needed" and "extremely important."
  2. Introduction, Lines 35-36:  It is very unusual to discuss amounts of wastewater in weight/mass units (tons).  Wastewater amounts are usually described in volume units (gallons, ft^3, m^3).
  3. Introduction, Lines 48-57:  The authors discuss the concept of wastewater propagation chains here, but only in vague terms.  This is a new concept and a separate paragraph, with appropriate references, should be included to explain the concept at a very basic level.
  4. Introduction, Line 66:  The authors start to use the terms "out-links" and "in-links" without ever formally introducing them or defining them.  The meanings of these terms are unclear.
  5. Introduction, Lines 68-75:  The authors introduce the term "average propagation length (APL)", note that it is used in the field of economics, and mention that it can be used in wastewater propagation chain analysis.  A separate paragraph should be devoted to this important concept, with more explanation of what is meant by APL, and with a tangible example of is relevance to wastewater generation.
  6. Introduction: The objectives of the work presented are not presented.  The last paragraph of the Introduction (Lines 96-103) discussed the content of the manuscript, but the objectives of the work are not stated.  The overall goal and the specific objectives (tasks) of the work should be presented explicitly.  The work seems to be a mixture of presentation of a new model and analysis of China's industrial wastewater generation, but the goals are unclear from the Introduction and from reading the subsequent methods and results sections.
  7. Data and Methodology, Section 2.1, Lines 105-111:  The sources and nature of the data used need to be described in more detail.  Further, the authors need to clarify whether their analysis includes municipal wastewater (domestic sewage), which will comprise the largest amount of wastewater generated.
  8. Data and Methodology, Section 2.2, Lines 112-149:  The model developed and employed by the authors needs to be described conceptually here, and not in purely mathematical terms.  The meanings of most of the variables mentioned are not clear.  The nature of the model and its function are unclear.
  9. Results, Section 3.1, Lines 150-179:  The results presented cannot be understood from the information presented.  Figures 1-4 are not interpretable.  There are no labels on the axes of these x-y plots, and the symbols presented on the plots are not defined either in legends on the plots or in the figure captions.  The results presented in the figures need to be introduced and explained with text.  The explanation of the results presented in the figures in Lines 166-173 is very brief, difficult to understand, and insufficient.
  10. Discussion, Lines 209-219:  This brief section repeats some previous overview statements about the model, and includes one sentence about how the work can be extended in future research.  The section is not well organized and does not present substantial information or insight.  
  11. Conclusions, Lines 220-239:  The conclusions are not well connected to or supported by the results presented.
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