Aqueous Phase from Hydrothermal Liquefaction: Composition and Toxicity Assessment

Round 1

Reviewer 1 Report

Yuliya et al. presents an original contribution ‘‘Biological Treatment of Hydrothermal Liquefaction Wastewater: composition and toxicity assessment’’. Based on my assessment, there are some points in this draft that needs to be given attention prior to its acceptance. More specifically, I would suggest having the RESULTS and DISCUSSION sections combined because only RESULTS are presented in this draft. There seems to be some discussion mixed with results but no dedicated section for DISCUSSION has been presented; the results need to be discussed in reference to previous studies. The detailed comments are as follows;

MAJOR POINTS

1. Abstract

L18-19, L26: Abbreviations (notably TOC, COD, BOD₅, WWTP and DR₅₀) should ideally be expanded at their first instance of use in the abstract. The same holds true for the main manuscript text.

L19: What are the units for DR₅₀?

 2. Introduction

L70: Unit of temperature should be indicated.

L84: 93,4 % >> 93.4%.

3. Methods

L170-171: Equation (1) should be cited in text, written and labelled appropriately. I suggest using the dedicated MS Word equation tool to do this.

L176, L309: What does DR₅₀ mean? Is it ‘‘Median lethal dilution rate’’ or ‘‘median lethal concentration’’?

L268, 275-276: Is DR the same as DR₅₀?

4. Results

Can we have this as RESULTS AND DISCUSSION?. There seems to be no discussion of results presented in this study.

L203-204: Please recheck the range of 6.5 and 9.3. The lower limit seems quite less compared to the values in Table 3. Or you may revise this line to read: the pH of the samples varied between 6.5 and 9.3.

In Тable 3;

-check the unit of Total inorganic carbon (g//dm3dm3?). In the same table, indicating the units in parentheses could improve the visualization of the data presented.

-Total organic C = TOC?  The presentation of the conditions in this table is rather confusing. What does the (SS, standard) and (PS, standard) mean?; possibly could you define these under the Table note?. Also, assess if you really need the ‘‘2 g’’ appended to some conditions. Why is there time for other conditions, and others not?. Check this ambiguity in Figures as well.

-PH has mean values with standard errors but the rest have no error values. Any explanations for this?

L206-207: Interesting observation, and is to be expected. Why? I would rather have the RESULTS and DISCUSSION sections combined, because this line evidently needs some citation(s). The authors also show some discussion in L209, where a citation of published literature is made.

For Table 6; HT, NT and LT should be defined.

Authors should check the manuscript draft for English language and some minor grammatical fixes

Author Response

Dear reviewer. Thank you so much for your invaluable contribution to improving our article. All your comments have been taken into account. I ask you to consider the full version of the responses to the comments attached to this message. Sincerely, Yulia Kulikova.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments to Authors:

The research article entitled “Biological Treatment of Hydrothermal Liquefaction 2 Wastewater: composition and toxicity assessment” is very interesting approach for surfactants degradation. The manuscript presentation is very good. This research work is valuable and merit publishing in “Water “after some major and minor revisions.

1. The title of manuscript should be revised and changed.

2. Abstract: Revise the keywords list and arrange them alphabetically.

3. Analysis of HTL-AP composition with NMR-spectroscopy method allowed establishing, that share of carbon in aliphatic chains was 34.05-41.82%, content of carbon incarboxyl groups and aromatic rings was 26.42-34.44%. The NMR spectra are missing in paper?

4. Line 43-44: Correct the concentration unit.

5. Phytotoxiciy assay is missing. Only Biotoxicity on Parame- 160 cium caudatum ciliates and nauplii of Artemia salina is not enough.

6. Statistical analysis section should be added in materials and methods.

7. Why Standard deviations (SDs) values are missing in Figure 1 to Figure 6.It is not a scientific measurements errors are possible.  

8. Why Standard deviations (SDs) values are missing in Table 4 to Table  6.

9. Check and revise the references. These should be in same style according to journal format.

10. Check the unit of temperature: 125-350 C

11. Check wether the spelling is correct: (USA, Newark)

12. Check: mgO/dm3

13. Controls are missing in the results.

14. The manuscript should be revised carefully. There are some minor grammatical mistakes throughout the manuscript.

15. What is the practical potential of this research work?

16. The authors should check plagiarism of manuscript.

Comments for author File: Comments.docx

The authors are directed to  revised the manuscript carefully. There are some minor grammatical mistakes throughout the manuscript.

Author Response

Dear reviewer. Thank you so much for your invaluable contribution to improving our article. All your comments have been taken into account. I ask you to consider the full version of the responses to the comments attached to this message. Sincerely, Yulia Kulikova.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

All my concerns has been adressed. However, L223-224 has some words not in English. The authors could recheck this. 

Needs to be edited prior to publication. The normal inhouse (pre-publication) English language correction of MDPI maybe adequate for this revision

Reviewer 2 Report

The authors have made revisions according to reviewer suggestions. I recommend the publication of the manuscript  however the title is not suitable. The title should be " Composition and Toxicity Evaluation of the Biological Treatment of Hydrothermal Liquefaction Wastewater"

Minor grammitical mistakes are still there and minor editing of english language is required required