Drying Characteristics of Chicken Manure Under a Variable Temperature Process

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper investigates the drying process of chicken manure. The problem of sustainable manure management in the poultry industry is emerging. Therefore the topic is up-to-date and in line with the scope of the journal. Nevertheless, the presented research is rather simple and barely sufficient for publication.

My detailed comments are:

The introduction is very brief. I would advise to emphasise, why is drying of chicken manure necessary. Is the manure further utilized, for example as a fuel in combustion units?

Table 2: Please explain TKN. In the case of moisture, ash and volatiles, please add the basis of analysis (as received, dry, dry ash-free etc.)

What was the mass of single manure samples?

Line 149: How did the Authors determine the weights assigned to each response factor?

In the Abstract, focus more on the findings, results and process parameters.

The scientific discussion of the paper is rather poor and should be developed. The same applies to the final conclusion. Please strengthen this aspects of the paper.

 

 

Author Response

Dear Reviewer,

 Thank you very much for your time and constructive comments concerning our manuscript. We all appreciate your hard-working. Those comments are valuable and very helpful for revising and improving our manuscript. Accordingly, we have carefully considered your suggestions and incorporated them into the revised version. We have also polished the whole manuscript again. For ease of identification, the revisions used red highlighted changes and addressed lines. The following are point-by-point responses, in red color, to your comments.

1. The introduction is very brief. I would advise to emphasise, why is drying of chicken manure necessary. Is the manure further utilized, for example as a fuel in combustion units?

Response 1: Thanks for your responsible review and constructive suggestion. Chicken manure drying is mainly aimed at removing the moisture from chicken manure for the production of organic fertilizer granules. Relevant expressions have been added to the manuscript.

2. Table 2: Please explain TKN. In the case of moisture, ash and volatiles, please add the basis of analysis (as received, dry, dry ash-free etc.)

Response 2: Thanks for your responsible comment. TKN (Total Kjeldahl Nitrogen) is the sum of ammonia nitrogen and organic nitrogen. TKN concentration of manure samples was determined using the Kjeldahl method. Moisture, Ash and Volatiles reflected the characteristics of initial fresh chicken manure, the moisture of the manure samples was determined using air drying in the oven. Ash refers to the proportion of inorganic material remaining in the drying process of chicken manure after removing water. Volatiles content is not related to the content studied in this paper, and relevant indicators are deleted. Relevant explanations have been added in the paper.

3. What was the mass of single manure samples?

Response 3:  The manure samples from different groups were placed in perforated tray(Φ=60mm) with the layer thickness of 40 mm, and the initial weight of manure samples was 125g. Relevant data have been added to the manuscript.

4. Line 149: How did the Authors determine the weights assigned to each response factor?

Response 4:  Thanks for your responsible review. Energy consumption, nitrogen loss, and drying time are the three key factors that farmers are most concerned about in the chicken manure drying  process. Given the priority of green production, energy consumption and nitrogen loss are slightly more important than drying time, and considering the field experience and previous research, we assigned them 35%, 35% and 30% weights respectively.

5. In the Abstract, focus more on the findings, results and process parameters.

Response 5:  Thanks for your  constructive suggestion, we have refined the abstract.

6. The scientific discussion of the paper is rather poor and should be developed. The same applies to the final conclusion. Please strengthen this aspects of the paper.

Response 6:  Thanks for your responsible comment and constructive suggestion. Related discussions have been added in the paper. The revised content has been marked in red in the manuscript.

Thank you  for your meticulous review.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

I suggest adding more specific numerical data from the study to the Abstract.

Please clearly indicate the purpose of the study at the end of the Introduction chapter

Table 3 – Where do the temperature changes come from? How did the authors plan this experiment?

216 - Correct the unit "kW h".

397 – The chapter should not end with a table.

Lack of novelity

Author Response

Dear Reviewer,

Thank you very much for your time and constructive comments concerning our manuscript. We all appreciate your hard-working. Those comments are valuable and very helpful for revising and improving our manuscript. Accordingly, we have carefully considered your suggestions and incorporated them into the revised version. We have also polished the whole manuscript again. For ease of identification, the revisions used red highlighted changes and addressed lines. The following are point-by-point responses, in red color, to your comments.

1. I suggest adding more specific numerical data from the study to the Abstract?

Response 1: Thanks for your  constructive suggestion, we have refined the abstract.

2. Please clearly indicate the purpose of the study at the end of the Introduction chapter

Response 2: Thanks for your valuable advice.  Related contents have been added in the paper.

3. Where do the temperature changes come from? How did the authors plan this experiment?

Response 3:  This method uses residual heat from chicken house ventilation in the early drying stage and uses auxiliary heat source in the late drying stage, which belongs to variable temperature process. So, there have a temperature increase during the drying process. In the practical application of utilizing residual heat from chicken house ventilation, the average temperature of the exhaust air in autumn and winter was approximately 20°C. In the second stage, the drying temperature can reach 45–65°C with the aid of auxiliary heating sources. Therefore, the drying temperature for the early stage was set at 20°C, while the second-stage drying temperature was set within the range of 45–65°C. At the same time, the air velocity was maintained between 0.6–1.8 m/s, and when the moisture content drops to the node between 35 and 55%, the auxiliary heat source starts to be used to increase the drying temperature, based on the environmental parameters at the application site. The experimental temperature setting of this study is mainly to simulate the temperature in the actual production process.

4.Correct the unit "kW h"

Response 4:  Thanks for your responsible comment and meticulous review. We have corrected the unit.

5.The chapter should not end with a table

Response 5:  Thanks for your  constructive suggestion. We have corrected the incorrect format.

 

Thank you  for your meticulous review.

 

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The paper titled “Drying characteristics of chicken manure under variable temperature process” is devoted to evaluating the effects of drying temperature, air velocity and moisture content nodes on drying characteristics, using drying time, energy consumption and nitrogen loss rate as key indicators.

The title reflects the paper content, the originality is good, and the interest to the readers is fully centred.

My specific comments are listed below:
Line 94: Could more information be added about chicken manure characteristics, such as pH or TAN? This would help the discussion of the nitrogen loss results.
Line 166: Why do you write "nitrogen loss rate" and not "total nitrogen loss" if it is expressed as a percentage and not as i.e. kg N/ day?
Lines 234-236: Did you measure the nitrogen loss of the early drying stage? Could you add this information?
Lines 329-343: Also, in this case, is it possible to add the nitrogen loss of the early drying stage since it affects the results of the second stage?

Author Response

Dear Reviewer,

Thank you very much for your time and constructive comments concerning our manuscript. We all appreciate your hard-working. Those comments are valuable and very helpful for revising and improving our manuscript. Accordingly, we have carefully considered your suggestions and incorporated them into the revised version. We have also polished the whole manuscript again. For ease of identification, the revisions used red highlighted changes and addressed lines. The following are point-by-point responses, in red color, to your comments.

1. Line 94: Could more information be added about chicken manure characteristics, such as pH or TAN? This would help the discussion of the nitrogen loss results.

Response 1: Thanks for your responsible review and constructive suggestion. We have added the pH to the properties of chicken manure samples.We measured the initial pH value of the chicken manure during the testing process of the characteristics of fresh chicken manure, but it was not presented in Table 1 previously. We regret that the TAN content was not tested in this study and we only studied total nitrogen in this paper.

2. Line 166: Why do you write "nitrogen loss rate" and not "total nitrogen loss" if it is expressed as a percentage and not as i.e. kg N/ day?

Response 2: We sincerely apologize for this mistake in our expression, we have changed  "nitrogen loss rate" to  "total nitrogen loss". We have made the necessary revisions in both the manuscript and the diagram.

3. Lines 234-236:Did you measure the nitrogen loss of the early drying stage? Could you add this information?

Response 3:  Thanks for your responsible review.We are very sorry. In this study, we only focused on the total nitrogen content at the beginning and end of the drying process, and did not test the changes of total nitrogen content during the drying process or in the early drying stage. Thank you again for your suggestion. We will add relevant research in further studies later. In another one of our studies titled "The Effect of Drying Temperature on Nitrogen Loss and Pathogen Removal in Laying Hen Manure", we investigated the changes in nitrogen content throughout the drying process. However, the study was mainly about constant-temperature drying, which is different from this paper.

4. Lines 329-343: Also, in this case, is it possible to add the nitrogen loss of the early drying stage since it affects the results of the second stage?

Response 4:  Thanks for your responsible review. We did not test the total nitrogen loss in the early drying stage, because this study focused more on the difference in total nitrogen at the start and end of the drying process. In the follow-up study, we will focus on the question you raised and the question above. Thank you again for your valuable advice.

 

The revised content has been marked in red in the manuscript. Thank you  for your meticulous review.

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The Authors have improved the manuscript. I can recommend it for publication in Applied Sciences.

Author Response

Thank you for your hard work and meticulous review. We have re-polished the manuscript. Also wish you success in your work, career flourishing.

Reviewer 2 Report

Comments and Suggestions for Authors

-

Author Response

Thank you for your hard work and meticulous review. We have re-polished the manuscript. Also wish you success in your work, career flourishing.