Biodesulfurization of Consortia Immobilized on Oil Palm Frond Biochar in Biotrickling Filters under Anoxic Conditions

Round 1

Reviewer 1 Report

Peer Review

Fermentation-2489192 (Sutarat et al.)

 

General comments:

 

I am not an expert on hydrogen sulfide removal, either by biologic or non-biologic means, so I must preface my remarks with that disclaimer; thus, I am not in a good position to judge the significance/usefulness of the study. The English in the manuscript, while not perfect, is quite acceptable. The data seem substantial (see below) and are presented clearly. In addition, the scholarship (citation of the relevant literature) is quite good.

 

One question is whether (as it seems to me from Figures 2, 4, and 6) the data are based on single runs with each of the four columns. If so, I think it would be good to state that explicitly, along with the limitations to the robustness of the data that this entails (I realize that it is challenging to repeat a run that lasts 5 months).

 

Specific comments:

 

1. In the Materials and Methods section at least some information on how the scanning EM’s were performed would seem necessary. Also in that section, I think it would be helpful to expand the description of the sequencing methods, particularly to explain how many individual reads were made from each library and how an unbiased determination of species abundance was ensured from the sequencing protocol.

 

2. I think a better plural for consortium would be “consortia”.

 

3. Lines 219-220, is the nitrate converted to N2 gas, which was or could not be measured. I was unsure of this and it might help to clarify this point.

 

4. Line 224 (and see General Comments above), how many measurements went into the 3.60 +/- 0.41 determination? Were they multiple measurements in a single run or from duplicate runs?

 

5. Line 176, did the authors mean to add “bound to” between were and dissociated?

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The work is relevant in the field of wastewater treatment and biogas treatment biotechnology. This study aims to investigate oil palm frond biochar immobilized with a consortium from industrial wastewater. Its effectiveness in reducing the amount of H2S gas and nitrogen is being investigated. The influence of initial H2S concentration in synthetic biogas, N/S ratio, dissolved oxygen and microbial community on the performance of the biofouling filter under anoxic conditions was investigated. The topic of the manuscript is very relevant in the field of research; therefore, this work should be a contribution to the valued research area. However, I have a few comments/questions that should be reviewed before posting:

1. The keywords do not fully reflect the topic of the work, perhaps "biotrickling filter", "oil palm frond biochar" should be inserted...

2. In analytical methods, the measurement limits and errors of devices/testing methods should be presented. Also, other information is related to the calculation of errors and the reliability of the results.

3. Information on the temperature of the biofilm should be provided;

4. Measurement errors are not presented in the results (figures) or their descriptions;

5. The article should be supplemented with a more detailed discussion based on similar results obtained by other authors. A separate discussion subsection has been inserted.

6. The article explains in more detail how the constant pH of the biofilm was ensured when the biofilm was exposed to H2S.

7. In the article, explain in more detail why SEM research was chosen on the 20th day. Why not during each phase?

8. The article explains in more detail why the efficiency of C-BTF increased so much: from 30% to 100% (in Figure 4).

9. Figure 5 is not clear. Fix layout (reduce characters, letters and text font size).

10. The article explains in more detail why microbiological tests were carried out for 51 days. Why not during each phase?

11. In the article, explain in more detail why there were different initial H2S concentrations (significantly different during all phases and days).

12. The list of references should be supplemented with publications more recent than 5 years.

After careful revision of my comments and revision of work, manuscript can be accepted for publication.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf