Preparation of Micron-Scale Activated Carbon-Immobilized Bacteria for the Adsorption–Biodegradation of Diesel Oil

Round 1

Reviewer 1 Report

The authors have prepared Micron-scale activated carbon (MAC) immobilized diesel oil degrading bacteria (bio-MAC), which was employed as a remediation material to remove diesel oil-contaminated water. In the manuscript, the author has covered all of the required aspects. This work still requires additional revisions before it can be published.

Specific comments:

1) Carbon-based absorbent material should be described in detail in the introduction section.

2) The author should discuss additional micron-scale activated carbons that are utilized for oil absorption or similar applications in the introduction section.

3) Check Fig. 6 and its caption.

4) How the bio-MAC shows better efficiency than the MAC/bacteria, should be discussed.

5) The more characterization techniques such as FTIR, XRD, etc. can emphasize the current version of the manuscript.

6) The comparative data of oil absorption with the various bacteria with the bio-MAC should be provided.

7) In the introduction part, author should include the following references as carbon-based materials which are used for oil separation to improve the quality.  

a.https://doi.org/10.1016/j.seppur.2021.118569

b. https://doi.org/10.1016/j.polymertesting.2020.106743

c. https://doi.org/10.1038/s41598-020-67231-y

d. https://doi.org/10.1002/slct.201900115

8) Author should provide a comparative table with other composites.

9) Figure 2. SEM images must be in the same magnification as the scale bar for better comparison.  

10) Author should improve the quality of the English.  

Author Response

Thank you very much for your letter dated May 16, 2022. We are very grateful to your comments for the manuscript (Water-1699203). Based on the comments and requests of you, we have responded to these comments one by one. Please see the attachmen.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study proposed the preparation of micro-scale activated carbon immobilized bacteria for the adsorption-synergic biodegradation of diesel oil. I recommend a major revision of the manuscript.  

      Some concerns and suggestions are listed below for the author's attention.

1. The introduction part needs to be enhanced by adding and discussing recent references. The authors can follow the recent references for improving the introduction part: Global water contamination and problems of poor sanitation & the effectiveness of the adsorption process by using biomaterials.
2. Which is the equations of biodegradation of diesel oil percentage, in this manuscript, please mention it in the method section.

1. Please provide the experimental conditions: adsorbent mass, solution volume, temperature, pH, time, mixing rpm, all the factors which are applicable, in the caption of figure 3&4.

1. Line No. 65 Add some previous studies that confirmed the removal of oil by activated carbon.
2. The paragraph from line 67-71 add what confirms this.
3. From line 72-79 paragraphs which express the aim of the study, this paragraph need language revision.
4. Adjust the order of the title to be: 2. Screening and enrichment of bacteria strains.
5. Add a reference for the media preparation method.
6. Line 127 Add a word (agitated) after 30 hours.
7. Move Table 2 to the Methods and Materials section.
8. Unite magnification for all figures especially figures number 2b in the SEM analysis.
9. Use the physical properties in the Methods section to help explain SEM analysis.
10. From lines 221-223, add confirmation of your interpretation from previous studies, with support this part with further discussion.
11. In line 245, edit the figure number.
12. In figure No. 5 make a redraw (change chart type) to show the species percentage.
13. In Section 3.4 this part needs further explanations.
14. In section 3.5, starting from line 257, the authors mentioned the adsorption-synergic biodegradation could be illustrated in two steps please sort these stages with more discussion and references.
15. The author introduced bacteria and microscale activated carbon can be used as adsorbents. Please introduce and explain the absorption mechanism of adsorbents and diesel oil.
16. Please provide FTIR spectrum of adsorbent to identify functional groups and compare degradation, before and after adsorption of oil.
17. In conclusion, section show the most important propose for future prospects.
18. English Language should be revised all over the manuscript to avoid minor grammatical errors and word typing mistakes in the manuscript.

Finally, I wish you all the best and success.

Author Response

Thank you very much for your letter dated May 16, 2022. We are very grateful to your comments for the manuscript (Water-1699203). Based on the comments and requests of you, we have responded to these comments one by one. Please see the attachmen.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Accept in present form after editing of English language.