Enhancing Mesophilic Anaerobic Digestion of Waste-Activated Sludge through Heat Pretreatment and Kinetic Modeling
, Baojian Xu 1, Ruina Zhang 4, Rajeev Goel 5, Mitsuharu Terashima 3 and Hidenari Yasui 3
Johan P.M. Sanders
Round 1
Reviewer 1 Report
the paper is difficult to read because many abbreviations are not mentioned even not in the Nomenclature section. IH, ASMs, ADM, MLSS, ..
The energy section does not give any explanation on how the conclusions have been drawn. What are the boundary conditions of the LCA? is e.g. included that a lot less energy will be required for drying and dewatering?
No economic statements?
Why pH development of the digestions are not mentioned
Why there is no indication of the nitrogen content of the sludge. Is the NH3 formation a considerable part of the total N? Has the NH3 concentration been measured of only inferred?
What happens with heavy metals? are they in these type of sludges?
Author Response
Response to Reviewer 1 Comments
Point 1: the paper is difficult to read because many abbreviations are not mentioned even not in the Nomenclature section. IH, ASMs, ADM, MLSS, ..
Response 1: Each abbreviation has its full name in the text. In addition, a glossary is attached at the end of the article, which provides detailed information. The explanation for IH has been added on line 113. Explanations of other abbreviations can be found in the text, such as ASMs on line 143, and so on.
Point 2: The energy section does not give any explanation on how the conclusions have been drawn. What are the boundary conditions of the LCA? is e.g. included that a lot less energy will be required for drying and dewatering? No economic statements?
Response 2: Thank you for your kind suggestions. At the request of other reviewers, this section has nothing to do with this article and has now been deleted.
Point 3: Why pH development of the digestions are not mentioned
Response 3: Thank you for your valuable suggestions. These influencing factors will be studied in the future.
Point 4: Why there is no indication of the nitrogen content of the sludge. Is the NH3 formation a considerable part of the total N? Has the NH3 concentration been measured of only inferred?
Response 4: Thank you for your valuable suggestions. NH3 of anaerobic fermentation of sludge is produced by protein degradation. The nitrogen content of the sludge was indeed not measured, but the ammonia content in the product was measured.
Point 5: What happens with heavy metals? are they in these type of sludges?
Response 5: Thank you for your valuable suggestions. These influencing factors will be studied in the future.
Reviewer 2 Report
The manuscript looks fine but the method and discussion sections can be better improved. The conclusion section should include limitations of the study and recommendations for future reseachs to overcome the mentioned limitations. Then the manuscript can be accepted for publication
Author Response
Response to Reviewer 2 Comments
Point 1: The manuscript looks fine but the method and discussion sections can be better improved. The conclusion section should include limitations of the study and recommendations for future reseachs to overcome the mentioned limitations. Then the manuscript can be accepted for publication
Response 1: Thank you for your valuable suggestions. At the request of the editor, Part 4 "Discussion" has been added, and the limitations of this study and future research plans have been included.
Author Response File: 
Author Response.docx
Reviewer 3 Report
Dear authors,
I congratulate you for the research presented in the paper.
I recommend publishing the paper after making these minor corrections.
In the abstract section, set it to 95 degrees Celsius.
In the keywords section, on line 18, put other words that are not found in the title of the work.
In line 87, describe what the experimental device in figure 2 consists of.
On line 119, describe what figure 3 contains.
From line 285 to 372, all references must be written according to the writing instructions of the journal.
1. Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range.
Author Response
Response to Reviewer 3 Comments
I congratulate you for the research presented in the paper.
I recommend publishing the paper after making these minor corrections.
In the abstract section, set it to 95 degrees Celsius.
Author’s answer：Thank you for your valuable advice. The error here has been corrected, see line 19
Point 1: In the keywords section, on line 18, put other words that are not found in the title of the work.
Response 1: Thank you for your valuable advice, as the meaning of "sewage sludge" and "waste-activated sludge" is similar, so they appear in both the title and keywords.
Point 2: In line 87, describe what the experimental device in figure 2 consists of.
Response 2: Thank you for your valuable suggestions. This is a schematic diagram of the experimental device. The detailed structure of the device has been described in the previous work, please refer to the study by Liu et al., 2019.
Point 3: On line 119, describe what figure 3 contains.
Response 3: Thank you for your valuable suggestions. The process in Figure 3 is explained in "3.2.4. Promoting effect of heat treatment on metal fertilization " section.
Point 4: From line 285 to 372, all references must be written according to the writing instructions of the journal.1. Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range.
Response 4: Thank you for your valuable suggestions. After verification, all reference formats have met the journal requirements
Author Response File: Author Response.docx
Reviewer 4 Report
This paper, entitled “Enhancing mesophilic anaerobic digestion of waste-activated sludge by heat pretreatment and its kinetics modeling”, is a scholarly work. The content is relevant to Sustainability Journal. Although the paper is well written and in good English, a few improvements must be done to increase its quality.
General comments are as follows:
Page 2, line 54 Please remove “our” from the sentence.
Please check all the acronyms have their meaning the first time they are used. For example, page 2 line 66: MBBR and page 2 line 86: CODcr
Please check acronyms and their full meaning they are used indistinctly though the paper.
Please explain the meaning of 0.5 times a week in page 3 line 93
Although last paragraph (3.3 Life cycle cost) addresses an important topic it could be removed from the paper without any inconvenience. Please consider eliminating or adding more information.
Author Response
Response to Reviewer 4 Comments
This paper, entitled “Enhancing mesophilic anaerobic digestion of waste-activated sludge by heat pretreatment and its kinetics modeling”, is a scholarly work. The content is relevant to Sustainability Journal. Although the paper is well written and in good English, a few improvements must be done to increase its quality.
General comments are as follows:。
Point 1: Page 2, line 54 Please remove “our” from the sentence.Dcr
Response 1: Thank you for your kind suggestions. This word has been deleted.
Point 2: Please check all the acronyms have their meaning the first time they are used. For example, page 2 line 66: MBBR and page 2 line 86: CODcr
Response 2: Thank you for your kind suggestions. The full name of COD has been explained.
Point 3: on line 98. In order to unify the name, the CODcr in line 104 has been changed to COD
Please check acronyms and their full meaning they are used indistinctly though the paper.
Response 3: Each abbreviation has its full name in the text. In addition, a glossary is attached at the end of the article, which provides detailed information.
Point 4: Please explain the meaning of 0.5 times a week in page 3 line 93
Response 4: 0.5 times per week means once every two weeks on average.
Point 5: Although last paragraph (3.3 Life cycle cost) addresses an important topic it could be removed from the paper without any inconvenience. Please consider eliminating or adding more information.
Response 5: Thank you for your valuable suggestions. This section has been deleted and will be studied in the future.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
No comments
