Shifts in the Microbial Community of Activated Sludge with Different COD/N Ratios or Dissolved Oxygen Levels in Tibet, China
Round 1
Reviewer 1 Report
Minor inaccuracy is: OTU is in several places and OUT in others. Should it be like that?
The whole text is ok.
Author Response
Dear Editor:
Many thanks for the insightful comments and suggestions of the referees. I have made corresponding revision according to their advice. Words in red are the changes I have made in the text.
The following is the answers and revisions I have made in response to the reviewers' questions and suggestions on an item by item basis.
Reviewer: 1
1. The acronyms of operational unit were OTU. OUT has been modified.
Thank you and best regards.
Yours sincerely,
Jin Xu
Reviewer 2 Report
Most of the comments were made by the authors in the second version
Author Response
Dear Editor:
Many thanks for the insightful comments and suggestions of the referees. I have made corresponding revision according to their advice. Words in red are the changes I have made in the text.
The following is the answers and revisions I have made in response to the reviewers' questions and suggestions on an item by item basis.
Reviewer: 2
1. Most of the comments have been modified in the second version.
Thank you and best regards.
Yours sincerely,
Jin Xu
Reviewer 3 Report
Dear Autor,
Again, you did not put your manuscript in the format provided by MDPI. You can download this format from https://www.mdpi.com/journal/sustainability/instructions.
I cannot see the reference for Chinese standards (Line 121)
The acronyms is OTU (Line 135) or OUT (Line 137)?. Please check carefully.
The letter inside all figures is very small. Again, your figures are very difficult to read. You did not any modification to the letters. Please, improve it. In Figure 8 and 9, the title for x-axis would be Time (days). Remember, the title for x-axis or y-axis in Figure must include name and unity for measured. Recommendation: print your paper and try to read the figures.
I could not understand, why you in this version change the maximum OD level using 4.0 mg/L (Line 101) instead of 5 mg/L (used in your previous version, Line 83). You don´t explain this change. You told anything about the use of this high oxygen concentration with any reference supporting this high use. I believe that you are right regarding the necessity of more oxygen for altitude, however, you did not include any reference supporting this sentence.
Author Response
Dear Editor:
Many thanks for the insightful comments and suggestions of the referees. I have made corresponding revision according to their advice. Words in red are the changes I have made in the text.
The following is the answers and revisions I have made in response to the reviewers' questions and suggestions on an item by item basis.
Reviewer: 3
1. Some format problems have been modified according to the author's instruction.
2. The reference for Chinese standards (Line 121) has been added.
3. The acronyms were OTU (Line 135). OUT has been modified.
4. All figures have been modified. The title for x-axis has been added Time (days) in the Fig. 8 and 9.
5. The DO was controlled at constant and more than 4mg/L to provide adequate oxygen during the different COD/N ratios test stages. Using more than 4mg/L (Line 101) in this version instead of 5 mg/L (used in your previous version, Line 83). I have been added any reference supporting the necessity of more oxygen for altitude.
Thank you and best regards.
Yours sincerely,
Jin Xu
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
Dear authors,
The subject of the manuscript is interesting. However, you must be improved in a significant way the text, if you wish to publish in this journal. You must be more diligent when you are describing your methodology and results. To next some improvements are describing for different parts of the text:
The manuscript is not in the format proposed by Sustainability. Remember, this journal has a specific format. Check the author's instruction.
Abstract: You have to be more specific with your results. For example, in line 20, ¿Are you talking about your numbers?. If the answer is yes, please put the numbers.
Introduction. This section is poor. You did not include enough numbers to understand the results. Line 33, for you, ¿What is a good performance?. Please tell me this with numbers. Line 42 and 43, ¿Are you sure about the correct use of nitration?, I believe you are talking about nitrification. Please check. Line 53, AOB, you did not define this acronymous. Finally, I could not find anything about the importance of developing this study in highlands areas: the variation in oxygen transfer due to variation in pressure and its influence on microbial communities.
Methodology: this part must be improved in a significant way. ¿What is the altitude of your experimental site?. Line 83, ¿How do you adjust the ph?. Line 85, what is the specific COD/N ratio for the different experimental conditions (CN-1, CN-2, CN-3, CN4), you have to include this information into the main text. Same recommendation for variations of dissolved oxygen. ¿Why Do you use the differents COD/N ratio and dissolved oxygen concentrations? Please give me one scientific reason. In my opinion, DO concentration above 5 mg/l is excessive. In line 99, you have to include reference to Chinese procedures for water quality evaluation. Please be more diligent when you describe your materials and methods.
Results and discussion: interesting results. However, the discussion has to be improved. You did not discuss the importance of your results for your experimental site (plateau). Ok, you told me something, but it is too short. The figures have to be improved, the letter inside them is small, very difficult to read. Line 140, you use the word "lot", but only you include two references, for me two no is a lot. Line 141, use the word "research" instead of "investigation", same recommendation for the whole text. ¿What is the importance of the abundance of different groups of microorganism in the organic matter and nitrogen consumption?. Part 3.3, with your figure is impossible to determinate if your description is ok. My suggestion is to find another way to show your results in a Figure, you have to change Figure 8 and 9. Same comment for Pat 3.4.
Conclusions: you have to change the discussion, so you have to change the results.
Reviewer 2 Report
1. The correlation relationship (statistical analysis) between Relative abundance and OTU Rank shown in Figures 1, 2 and 3 should be provided and described in the text.
2. The results shown in figures 8 and 9 should be described in detail in the text. They are currently described briefly.
3. The work is missing statistical analysis of the results shown. Statistical analysis allows a better understanding of the research problem.
4. The chapter "Conclusions" is unacceptable. This chapter should contain a brief description of the results obtained and not give again the purpose of the work
Reviewer 3 Report
The paper is very interesting and the research is ingenious. I read with great interest. It would be nice to add some information. Then it would be better to understand the essence of the research..
1. Lines 83-88 - Do I understand correctly? 1) CN1 ...CN4 COD?N = 4; 5; 7; 10 and DO = 5+-0,5 mg/L? 2) DO1 ...DO4 = 0,5-1,0 ... 2,5-3,0 mg/L COD/N=7 ? If so then 5mg / L is very much, and besides this is a methodical error. More conclusions would be if the DO was one of DO1 ... DO4.
2. I understand that the research reactor was cyclical, i.e. SBR. If so, it would be good to add a decanting factor (fd). So how many wastewater was exchanged in each cycle (Ve). Vd = 0.045 m3; fd = Ve / 0.045.
3. Lines 109-120 - These 3 parts can be combined into one. The vast majority of words are repeated.
4. Fig. 2; 3 i 4 - How was calculated "Relative Ambundance" and how to interpret them? How to understand OTU Rank? Does he have any units? How to understand that part of broken curves ends at lower horizontal axis values? There is no discussion of these charts and the wording of the conclusions.
5. "Relative Ambundance" on Fig. 5; 6 and 7 have units % while in Fig. 2; 3 and 4 there are no units, and there is a logarithmic scale. How were the individual values calculated in each case?
6. In wastewater treatment studies, the temperature of wastewater is important. What was it like in this case? Constant or variable?
7. The sentence in lines 34-36 "Nevertheless, the wstewater..." is very interesting. It is a pity that the authors did not address these specific conditions further in this study. What was the problem with wastewater oxygenation? Was it easier to sediment active sludge as a result of degassing?
