Enhanced Sewage Sludge Disintegration and Nutrients Release by Catalytic Microbubbles Ozonation Using Sewage Sludge-Based Char as Catalyst
Round 1
Reviewer 1 Report
The reviewed paper concerns sewage sludge disintegration and nutrients release by catalytic microbubbles ozonation. The manuscript is well prepared and requires only minor corrections before publication. It is not clear to me how the ozone dose was controlled and how the microbubbles were generated. Please define the size of the bubbles, inlet ozone concentration and its flow rat. Please also estimate the ozone consumption during the process by define the concentration of ozone gas at the output of the reactor chamber. These data are necessary to recover experimental conditions and allow their future verification.
Author Response
Point 1: The reviewed paper concerns sewage sludge disintegration and nutrients release by catalytic microbubbles ozonation. The manuscript is well prepared and requires only minor corrections before publication. It is not clear to me how the ozone dose was controlled and how the microbubbles were generated. Please define the size of the bubbles, inlet ozone concentration and its flow rat. Please also estimate the ozone consumption during the process by define the concentration of ozone gas at the output of the reactor chamber. These data are necessary to recover experimental conditions and allow their future verification.
Response 1: Thanks the reviewer for the suggestion. The millibubbles are produced by a stainless-steel diffuser (MBO-75S, China) and the size range of the millibubbles was estimated by analyze the snapshot using Nanoparticle Tracking Analysis Technology. The output flow rate of inlet ozone concentration was controlled at 90 mg/L and ozone concentration is determined by the iodometric method. The Figure R1 show that the whole distribution diagram of bubbles particles in the range of 0 to 600 nm within 20 minutes after Nanoparticle Tracking Analyzer (LM10-HSBFT14) start-on and most of particle were 100 nanometers, which is also relatively stable.
Figure R1. Particle size distribution map of bubbles nanoparticles.
Changes made: We have added the Particle size distribution map of bubbles nanoparticles. (Figure. 2) in the revised manuscript.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear authors,
Dear authors, I congratulate you for your research, the presented manuscript deals with the current global problem. I recommend some corrections, as follows: in the introduction section, point out the objectives of the work to increase the usefulness of the work, additions should be made to increase the scientific value of the manuscript.
Describe table 1, write what the terms MLSS, MLVSS and SCOD represent when they first appear.
Explain what you found in figures 2a and 2b, 3a and 3b.
Row 74, only the table in bold, the name without bold.
Row 95, 3.1 Characterizations of SC, without bold, italic
Row 135, Comparative performance of phosphorus and nitrogen release by microbubble 135 ozonation with and without SC addition bold, italic
In line 149, As most literature suggested, I recommend that you specify some works from the literature.
Characterize figure 4.
Row 154, 155, number the chemical reactions
Row 165, 3.4 Effect of pH on the performance of SC catalyzed microbubble sludge ozonation, without bold, italic
Row 178, 179 number the chemical reactions
The Conclusions section should be improved.
Lines 2 9. 37, 44, 45, 57, 61, 111, 256, 257 [36], [37] correctly pass the sources, not as an index
Lines 306-380, all references written according to the writing instructions of the journal
e.g. 1. Gao, J.; Liu, Y.; Yan, Y.; Wan, J.; Liu, F. ...
Check the writing instructions of the journal.
Author Response
Thanking you very much for your consideration, we remain with kind regards. We are submitting a revised and reformatted manuscript entitled “Enhanced sewage sludge disintegration and nutrients release by catalytic microbubbles ozonation using sewage sludge-based char as catalyst” as research paper for Sustainability. We greatly appreciate the comments by the reviewers and the editor about the manuscript. All suggestions and comments were followed and answered, and several changes were accordingly made to the manuscript. Detailed responses to the reviewers’ criticisms and suggestions can be found below. We hope that the revised manuscript is now suitable for publication. Thank you for your time and effort in considering our manuscript.
Point 1: Describe table 1, write what the terms MLSS, MLVSS and SCOD represent when they first appear.
Response 1: We appreciate the reviewer’s suggestion. According to the comments, we have added what the terms MLSS, MLVSS and SCOD represent in table 1.
Point 2: Explain what you found in figures 2a and 2b, 3a and 3b.
Response 2: We thank the reviewer for the suggestion. According to figures 2a and 2b, we concluded that “These results demonstrated that SC with good crystallinity can provide many stable active sites for the catalytic reaction induced by microbubble ozonation.” Figures 3a and 3b demonstrated that “The obvious synergetic effect on both microbubbles and SC catalyst was mainly attributed the high ozonation utilization efficiency in SC catalyzed sludge oxidation system, which produce the formation of hydroxyl radicals for sludge disintegration and lysis.” These results were provided in the revised manuscript.
Point 3: Row 74, only the table in bold, the name without bold.
Response 3: Thanks the reviewer for the suggestion. We have revised the form with the table in bold and the name without bold in row 74 in the revised manuscript.
Point 4: Row 95, 3.1 Characterizations of SC, without bold, italic.
Response 4: We thank the reviewer for the suggestion. According to the suggestion of the reviewer, we have revised the form with the title “characterizations of SC, without bold” in the revised manuscript.
Point 5: Row 135, Comparative performance of phosphorus and nitrogen release by microbubble 135 ozonation with and without SC addition bold, italic.
Response 5: Thanks for your suggestion. We have revised the form with the title “Comparative performance of phosphorus and nitrogen release by microbubble ozonation with and without SC addition bold” in the revised manuscript.
Point 6: In line 149, As most literature suggested, I recommend that you specify some works from the literature. Characterize figure 4.
Response 6: We appreciate the reviewer’s suggestion. According to the comments, the literature Ref. 35 (Chem. Eng. J. 2021, 409, 128024), 36 (Adv. Sci. 2022, 9, 2204205), 37 (J. Hazard. Mater. 2019, 363, 119) were added in the revised manuscript.
Point 7: Row 154, 155, number the chemical reactions.
Response 7: We appreciate the reviewer’s suggestion. We have added the number of chemical reactions in row 166, 167.
Point 8: Row 165, 3.4 Effect of pH on the performance of SC catalyzed microbubble sludge ozonation, without bold, italic.
Response 8: Thanks the reviewer for the suggestion. We have revised the form with the title “Effect of pH on the performance of SC catalyzed microbubble sludge ozonation” in row 177 in the revised manuscript.
Point 9: Row 178, 179 number the chemical reactions.
Response 9: We thank the reviewer for the comments. We have added the number of chemical reactions in row 190, 191.
Point 10: The Conclusions section should be improved.
Response 10: Thanks for your suggestion. According to the comment of the reviewer, we have improved the conclusions section in the revised manuscript as follow: “Therefore, the novel combination of SC and microbubble ozonation was proven to be a promising solution for sewage sludge disintegration”.
Point 11: Lines 2 9. 37, 44, 45, 57, 61, 111, 256, 257 [36], [37] correctly pass the sources, not as an index.
Response 11: We appreciate the reviewer’s suggestion. We have revised the manuscript carefully.
Point 12: Lines 306-380, all references written according to the writing instructions of the journal e.g. 1. Gao, J.; Liu, Y.; Yan, Y.; Wan, J.; Liu, F. ....
Response 12: Thanks the reviewer for the suggestion. We have revised the form of all references according to the writing instructions of the journal.
Point 13: Check the writing instructions of the journal.
Response 13: Thanks for your suggestion. We have carefully checked the writing instructions of the journal.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
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