Effects of Different Heat Treatment Methods on Organic Pollutants and Heavy Metal Content in Oil Sludge Waste and Ecotoxicological Evaluation

Round 1

Reviewer 1 Report

The study evaluates and compares three different methods of thermal treatment of oil sludge waste on organic and inorganic composition of the residues and the effect of their blending with soil on the plant toxicity. The aim of the study is practical (removing toxicants from soil and desert greening) and the paper is interesting. Therefore, it can be accepted for the publication in Applied Sciences journal. Nevertheless, minor revision prior to its publication is recommended, as specified below.

Specific comments and suggestions

Title. In my opinion, “plant toxicity“, “ecotoxicological indices“, “germination“ or “plant growth“ could be mentioned there as it is the most important part of the study (now the end of the title is too general). It could be mentioned also within the keywords.

Section 2.1. including Table 1: I suggest providing the details of all three procedures (pyrolysis, thermal washing, and high-temperature oxidation) within the text. Big pieces of text within the table should be replaced by a brief information on temperature, agents, time etc. Please provide more information on pyrolysis and high-temperature oxidation, I presume that the dominant difference (except the temperature) was that the pyrolysis was conducted without the access of air and the oxidation was carried out using air atmosphere – is it true? Is “high-temperature oxidation“ used for combustion or is there some other difference? Table 1 – the last row – the “residue“ could be deleted as it is not mentioned in case of thermal washing and pyrolysis. All the three samples in Table 1 are residues. It could be mentioned also that Tween 80 is a surfactant (detergent). Table 2 is good.

Fig. 1 – caption. To the current caption (Preparation of residue by different heat treatment) I would add also “and plant experiment“ or “and phytoremediation“ or something like this (as photographs of the potted plants are also displayed there).

Reference list: please check the names of the authors – i) instead of “et al“ all the names of all authors should be mentioned and ii) in some instances the last names are not correct.

Author Response

Thank you for your letter and the referee’s evaluation and comments on our paper “Effects of different heat treatment methods on organic pollutants and heavy metal contents in oil sludge waste and ecotoxicological evaluation” (ID:applsci-1640144). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have revised the manuscript according to you kind advices and referee’s detailed suggestions. Here we attached the revised manuscript in the formats of both PDF and MS word. A response to the referees is enclosed, and the revised parts are marked in red in the paper.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript requires revision of English language before continuing submission. The content of the work is confusing. All plants need organic matter to grow, however the authors make measurements of organic matter. In fact, the authors mention that hexadecane and octadecane have growth properties for plants. However, on the other hand they relate this content to the abnormal growth of plants. This needs to be presented in a more scientific way.
Figure 2 shows chromatograms that will be important for authors, but not for presentation in a scientific article.
Other figures do not present results clearly. Furthermore, figure 4(d) is a consequence of figures 5, or vice versa. Either one should be removed.

Author Response

Thank you for your letter and the referee’s evaluation and comments on our paper “Effects of different heat treatment methods on organic pollutants and heavy metal contents in oil sludge waste and ecotoxicological evaluation” (ID:applsci-1640144). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have revised the manuscript according to you kind advices and referee’s detailed suggestions. Here we attached the revised manuscript in the formats of both PDF and MS word. A response to the referees is enclosed, and the revised parts are marked in red in the paper.

Author Response File: Author Response.docx

Reviewer 3 Report

In the reviewed manuscript, in the title “Effects of different heat treatment methods on organic pollutants and heavy metal contents in oil sludge waste and environmental risk assessment.”

The authors point out that waste in the form of oily sludge is a pressing environmental problem (production of 60 million tons per year). They contain a large number of organic compounds (including undesirable pesticides) and heavy metals. Therefore, it is important to find an effective method to detoxify them and a way to manage them.

The author studied the heat treatment of oil sludge residues from three different treatment methods (pyrolysis, heat washing, and high-temperature oxidation). The residues from treatment methods were chemically characterized and used in toxicity tests. Based on this study author concluded that the residues showed different ecological toxicity due to their organic and inorganic composition (heavy metals). Overall, the manuscript is well written, with data to support the discussion and conclusion. Therefore, I recommend considering this manuscript for publication without any changes.

Author Response

Thank you for your letter and the referee’s evaluation and comments on our paper “Effects of different heat treatment methods on organic pollutants and heavy metal contents in oil sludge waste and ecotoxicological evaluation” (ID:applsci-1640144). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have revised the manuscript according to you kind advices and referee’s detailed suggestions. Here we attached the revised manuscript in the formats of both PDF and MS word. A response to the referees is enclosed, and the revised parts are marked in red in the paper.

Author Response File: Author Response.docx

Reviewer 4 Report

The authors present an interesting study especially considering the environmenta issues the world is currently faced with. 

Comments:

_ There are continuous grammatical errors throughout the manuscript that need to be fixed. We suggest the authors go through the whole article article and also fix some of the construction on the sentences

-In Fig 5, the inner labelling is blurred, the font needs to be increased and expand the figures

_ The novelty within the manuscript is not well docummented , authors are encouraged to highlit it.

_ Within the abstract, especially when stating the findings, that section needs to be rewritten. In the abstract section we cant use words for example should not exceed, but rather we need to be given direct results and what they mean. 

Author Response

Thank you for your letter and the referee’s evaluation and comments on our paper “Effects of different heat treatment methods on organic pollutants and heavy metal contents in oil sludge waste and ecotoxicological evaluation” (ID:applsci-1640144). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have revised the manuscript according to you kind advices and referee’s detailed suggestions. Here we attached the revised manuscript in the formats of both PDF and MS word. A response to the referees is enclosed, and the revised parts are marked in red in the paper.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The manuscript has been adequately improved but a revision of English language is still needed. I consider Figure 2 can be eliminated, not the analytical results, but Figure itself does not give information.

Author Response

Dear Editors and Reviewers:
Thank you for your letter and the referee’s evaluation and comments on our paper “Effects of different heat treatment methods on organic pollutants and heavy metal contents in oil sludge waste and ecotoxicological evaluation” (ID:applsci-1640144). Those comments are all valuable and very helpful for revising and improving our paper, We have made corrections which we hope meet with approval. Revised portions are marked in red on the paper. The main corrections in the paper and the responses to the reviewers’ comments are as follows: 

Comment 1: The manuscript has been adequately improved but a revision of English language is still needed.

Response: Thank you for your helpful comments. In order to make the language and style of English more accurate, we have invited a native English professor to revise the article, and carefully revised and improved the English issue. Revised portions are marked in red on the paper.

Comment 2: I consider Figure 2 can be eliminated, not the analytical results, but Figure itself does not give information.

Response: Thank you very much for reading this manuscript carefully. According to your suggestion, Figure 2 has been deleted. The revised manuscript is shown in the annex.

We are really appreciated the helpful suggestions and thoughtful comments from editor and all of reviewers!!!

We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. We appreciate for Editors/Reviewers’ warm work earnestly, and hope that the correction will meet with approval. Once again, thank you very much for your comments and suggestions.

Best regards

Sincerely yours

Yu Tao

College of Chemistry and Chemical Engineering, Shaanxi Province Key Laboratory of Environmental Pollution Control and Reservoir Protection Technology of Oilfields, Xi’an Shiyou University, Xi’an, 710065 China

TEL: 029-88382699

Fax: 029-88382699

Email: [email protected]

Author Response File: Author Response.pdf