Upgrading Denitrification by Optimal Adsorption of SCFAs from Sludge Alkaline Fermentation Liquid by Acid-Modified Sepiolite

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Comments:

1- It is suggested that the manuscript undergo a language review to enhance its written style.

2- It was advantageous to analyse the concentration of the heavy metals in the extracted short-chain fatty acids solution to understand its impact on the biological process.

3- How can we avoid the alkaline pH affecting methanogenic activity?

   

 

   

comments:

1- It is suggested that the manuscript undergo a linguistic review to improve its writing style.

2- It was useful to analyze the concentration of heavy metals in the extracted short-chain fatty acid solution to understand their effect on the biological process.

3- How can we avoid the effect of alkaline pH on methane production activity?

 

Comments on the Quality of English Language

 

   

 

   

comments:

1- It is suggested that the manuscript undergo a linguistic review to improve its writing style.

2- It was useful to analyze the concentration of heavy metals in the extracted short-chain fatty acid solution to understand their effect on the biological process.

3- How can we avoid the effect of alkaline pH on methane production activity?

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The paper entitled "Upgrading denitrification by optimal adsorption of SCFAs from sludge alkaline fermentation liquid by acid-modified sepiolite" is devoted to an improvement of denitrification under limited range of conditions in the presence of acid-modified sepiolite. It should be noted that this topic is important not only from technological point of view, but also in terms of practical application in several branches of industry. Given the simplicity and low cost of the method disclosed, it definitely has prospects for further development.

In this work, the authors (i) investigated the effects of initial alkaline fermentation liquid concentration, acid-modified sepiolite dosage, pH value and temperature on alkaline fermentation liquid adsorption efficiency and obtain the optimal adsorption condition based on response surface methodology; (ii) explored the underlying adsorption mechanism by kinetic and isotherm study and by the surface and structural feature analysis of acid-modified sepiolite via scanning electron microscope, brunauer-emmett-teller, X-ray diffractometer and fourier-transform infrared analysis; (iii) evaluated the nitrate removal efficiency and carbon utilization with acid-modified sepiolite carried with alkaline fermentation liquid as carbon source. In conclusion, there were given some recommendations for upgrading identification by maximizing short-chain fatty acids extraction efficiency from alkaline fermentation liquid available for denitrifying bacteria.

The findings and recommendations of the authors are based not only on practical observations, but also on a fairly large set of fundamental inferences, which in the long run may contribute to the development of a general model for denitrification in the presence of acid-modified sepiolite. It should be underlined that the methods used by the authors (scanning electron microscopy, brunauer-emmett-teller method, X-ray diffractometer and fourier-transform infrared analysis) are classic for such type of research. Therefore, the results obtained do not raise questions. Generally, the paper is well presented. The graphics is very clear and convincingly illustrates the data described.

However, in opinion of this reviewer, the introduction is too fuzzy and inconsistent that somewhat occludes understanding of the main idea of the paper. The authors should either systematize the information or expand the introduction more clearly justifying the urgency and significance of the work. There is all the more reason for this as in the Materials and methods section, it was mentioned that some of the data were collected from a real enterprise (the Beijiao wastewater treatment plant in Shanxi, China), and were not obtained in a laboratory as model samples.

In addition, it is obvious that the authors have collected quite a large set of data that can be processed statistically. Accordingly, given the current realities, the authors are recommended to use their data for creation of model(s) within the framework of machine learning and artificial intelligence algorithms. This would significantly help in prediction of optimal conditions for dentification and any other side processes.

The authors used model temperatures of 10, 20, 30 and 40 °C for their experiments. It would be interesting to see how the experimental results change at 3-4 °C, i.e. at temperature of maximum density of water.

The paper is not free from errors that should be corrected before publication, namely:

The references are not formatted uniformly: in some cases there is a space between the reference and text, in others it is absent.

The font size in the equations should be the same as in the main part of the text. In addition, the font itself should be uniform in all equations.

The text contains typos, namely, missing spaces ("bySEM"), the absence of lower case in some formulas ("N2 adsorption"), the use of both degrees of centigrade and Kelvin (this should be unified), etc.

Author Response

Please see the attachment.

Author Response File: Author Response.docx