Evaluation of Maturity and Greenhouse Gas Emission in Co-Composting of Chicken Manure with Tobacco Powder and Vinasse/Mushroom Bran

Round 1

Reviewer 1 Report

The paper represents a descriptive experimental work about the composting of chicken manure using a combination of tobacco powder with vinasse or mushroom spent substrate (mushroom bran) as bulking agents. Different physical chemical variables were measured over time along with specific emissions generated during the composting process. The authors report interesting data related to the influence of mixing vinasse or mushroom bran with the tobacco powder to improve the composting indicators.

 

The paper is coherent among its different sections. The discussion of the results obtained is consistent with the methods employed. The English level of the manuscript should be improved. In particular, there are some confusing sentences that must be corrected to improve the general understanding of the manuscript (e.g., lines 45-51, 54-55, 62-63, 67, 156-158, 162-163, 357-358). In general, the paper could be improved in order to be published in Processes journal.

 

In the Introduction section, the effect of the carbon/nitrogen ratio (C/N) of each feedstock used (chicken manure, tobacco powder, vinasse, and mushroom bran) on the behavior of the composting process should be better explained. If the C/N of chicken manure is low (< 5), it is not clear why the tobacco powder is used as the basic bulking agent considering that the same manuscript states that this material “needs to be mixed with bulking agent with high carbon content”; this means that the C/N of tobacco powder is also low. On the other hand, the presence of bacteria in mushroom residue should be explained, considering the statement presented in lines 159-160; where do these bacteria come from?

 

In the Introduction section, some words should be added about the critical effect of the scale and size of the compost mass on the performance of composting process; in particular, the size of the piles directly affects the ability of the process to reach high temperatures (65-70ºC), required for compost disinfection and enhanced degradation of organic matter. Composting processes conducted in small-scale pilot bioreactors do not necessarily reflect the behavior of the degradation process at the commercial scale (mainly performed in piles arranged in big windrows, not in bioreactors), so the importance of studying small-scale composting processes in bioreactors should be clearly justified.

 

In the Materials and Methods section, it is worthy to describe the determination of the E4/E6 ratio. Why weren't some combinations of vinasse with mushroom bran taken into account?

 

In the Results and Discussion section, it is necessary that the scale issue be briefly analyzed, especially when temperature profiles are discussed. Again, the significance and usefulness of the results obtained at 60 L-bioreactor should be highlighted in the framework of designing more efficient methods for composting chicken manure on a commercial scale.

 

In general, the results are appropriately presented, but the level of discussion should be improved in order not to publish merely descriptive work. In particular, the authors should try to explain in a deeper way why the addition of vinasse or mushroom spent substrate cause beneficial effects on the final compost product. In particular, the authors should explain the differences in the behavior of these two materials when added to the tobacco powder and chicken manure from the chemical or biochemical viewpoint.

 

Some statements or sentences in the text appear to be not sufficiently supported, considering the experimental data provided. In particular, the sentences in lines 152-154 and 274-275 were not adequately supported in the experimental data on degradable organic matter degradation (not presented in the manuscript). Was this degradation estimated based on the total organic content of the samples taken? If so, this calculation was not disclosed in the Material and Methods section. Or was this degradation measured through the CO2 evolved from compost? On the other hand, the pile oxygen concentration is mentioned in lines 183-184. How was the pile oxygen concentration measured considering that oxygen concentrations reported were determined in the exhaust gas? Was an oxygen saturation probe used to determine the pile oxygen concentration (i.e., within the pile)?

 

C/N ratios during the composting process for the different treatments did not show noticeable reductions. In fact, the carbon/nitrogen ratio of the initial mixture of feedstocks should be between 30 and 35 to ensure the appropriate conditions for the microorganisms to decompose and transform the organic matter although values down to 25 can be used but with an increase in the overall time of composting, according to many authors. Moreover, when temperature increases, ammonia evaporation also increases and when C/N ratio is less than 18, the microorganisms transform the nitrogen in a higher degree, favoring its volatilization. In this case, the initial C/N ratios were in the range between 14 and 11. The C/N ratios at the end of the composting process should be in the range between 10 and 20 with the most stable composts falling in the lower end of this range. Considering these facts, the analysis level of the results obtained should be improved, especially if the authors consider the different components of the compost piles assessed. It is worthy to include the initial C/N ratios for each treatment in Table 2. In the introduction, it is stated that the C/N ratio of chicken manure is less than 5 (line 40), but the experimental value obtained for this same material was 15.1. How can this difference be explained?

 

In the supplementary material, provide the ANOVA or other results of the statistical analysis required to support some of the results presented in the text (e.g., when statistically significant differences were obtained between the treatments).

 

The discussion of the data presented in Fig. 4 is somewhat confusing. The text should be improved to clearly present which data correspond to the treatments with the addition of vinasse and which to the treatments with the addition of mushroom bran (lines 276-279). How were the cumulative emissions calculated? (I consider that the citation of previous works that include some key methods is not enough; these methods or calculation procedures should be briefly described in the manuscript). The authors suggest in line 307 that the aerobic microorganisms can inhibit the nitrification process, but the data obtained show that nitrate can increase at the end of the composting process, i.e., the nitrifying bacteria increase their activity; how can the authors interpret this issue?

 

In the Conclusions section (or at the end of the Results and Discussion section), specific recommendations to perform the composting process considering the results obtained and the goals of the process itself should be included, along with some economic considerations. In particular, potential applications in candidate crops could be mentioned.

 

Minor comments:

• Line 34: remove the space before the percentage sign (and unify throughout the manuscript).
• Line 35: “Aerobic composting was an effective…” Why in past, is it not true for the present time? The same comment for line 53.
• All the abbreviations should be deciphered as they first appear; some abbreviations of the methods are not deciphered.
• Table 1: there should be an annotation or remarks stating that the data are determined on a dry basis.
• Line 101: change the multiplication sign for the units (it is not a dot).
• Figure 1 and Table 3: all the abbreviations should be deciphered as remarks or in the captions.
• Line 234: “Good” and not “Well”.
• Line 284: “reduced” and not “reduce”.
• Lines 299-302: too much data; another way to present these results is suggested.
• Line 316: remove the minus signs.

Author Response

Reviewer #1:

1. The English level of the manuscript should be improved. In particular, there are some confusing sentences that must be corrected to improve the general understanding of the manuscript (e.g., lines 45-51, 54-55, 62-63, 67, 156-158, 162-163, 357-358). In general, the paper could be improved in order to be published in Processes journal.

Response: Many thanks reviewer’s comments and suggestions. Modifications have been made accordingly.

 

2. 2.In the Introduction section, the effect of the carbon/nitrogen ratio (C/N) of each feedstock used (chicken manure, tobacco powder, vinasse, and mushroom bran) on the behavior of the composting process should be better explained. If the C/N of chicken manure is low (< 5), it is not clear why the tobacco powder is used as the basic bulking agent considering that the same manuscript states that this material “needs to be mixed with bulking agent with high carbon content”; this means that the C/N of tobacco powder is also low. On the other hand, the presence of bacteria in mushroom residue should be explained, considering the statement presented in lines 159-160; where do these bacteria come from?

Response: We totally agree with review’s opinion, tobacco powder was also with low C/N ratio (mentioned in Line 47) which need to composted with those bulking agents (e.g., mushroom residue) with high C/N ration (22.9). In addition, mushroom residue was the residue of edible fungi, previous studies stated that mushroom residue was rich in bacteria too (Ramteke et al., 2020). We have revised accordingly in Line 55-63

Ramteke A Y, Nayak A, Sagar A, et al. Recent advances in mushrooms preservation[J]. Internatinal Journal of Chemical Sciences, 2020, 8(2): 2376-2381.

 

3. 3.In the Introduction section, some words should be added about the critical effect of the scale and size of the compost mass on the performance of composting process; in particular, the size of the piles directly affects the ability of the process to reach high temperatures (65-70ºC), required for compost disinfection and enhanced degradation of organic matter. Composting processes conducted in small-scale pilot bioreactors do not necessarily reflect the behavior of the degradation process at the commercial scale (mainly performed in piles arranged in big windrows, not in bioreactors), so the importance of studying small-scale composting processes in bioreactors should be clearly justified.

Response: Many thanks for reviewer's comments, we will further explore the difference between the composting process of small-scale pilot bioreactor and that of commercial scale in the future work.

 

4. 4.In the Materials and Methods section, it is worthy to describe the determination of the E4/E6 ratio. Why weren't some combinations of vinasse with mushroom bran taken into account?

Response: The determination of the E4/E6 ratio was highlighted in Line 151-153. In addition, we agree with reviewer’s suggestion that the combination of vinasse and mushroom bran were also good choice for successful chicken manure compost, however, we focused on the effect of these bulking agents on the combined compost of tobacco and chicken manure, so this treatment was not set in this study.

 

5. In the Results and Discussion section, it is necessary that the scale issue be briefly analyzed, especially when temperature profiles are discussed. Again, the significance and usefulness of the results obtained at 60 L-bioreactor should be highlighted in the framework of designing more efficient methods for composting chicken manure on a commercial scale.

Response: Many thanks for reviewer’s valuable suggestions again, lab scale experiment was indeed limited in revealing the compost performance in commercial scale, herein, future recommendation of this work was proposed in the conclusion.

 

6. In general, the results are appropriately presented, but the level of discussion should be improved in order not to publish merely descriptive work. In particular, the authors should try to explain in a deeper way why the addition of vinasse or mushroom spent substrate cause beneficial effects on the final compost product. In particular, the authors should explain the differences in the behavior of these two materials when added to the tobacco powder and chicken manure from the chemical or biochemical viewpoint.

Response: The reason for explaining the beneficial effects of vinasse or mushroom spent were respectively shown in Line 224-226, and Line 256-259. In addition, the proposed reasons for explaining the differences in the behavior of these two materials were attributed to differences among their porosity (Line 307-308), nutrient content (Line 255-258) and microbe community (Line 242-245).

 

7. Some statements or sentences in the text appear to be not sufficiently supported, considering the experimental data provided. In particular, the sentences in lines 152-154 and 274-275 were not adequately supported in the experimental data on degradable organic matter degradation (not presented in the manuscript). Was this degradation estimated based on the total organic content of the samples taken? If so, this calculation was not disclosed in the Material and Methods section. Or was this degradation measured through the CO2 evolved from compost? On the other hand, the pile oxygen concentration is mentioned in lines 183-184. How was the pile oxygen concentration measured considering that oxygen concentrations reported were determined in the exhaust gas? Was an oxygen saturation probe used to determine the pile oxygen concentration (i.e., within the pile)?

Response: In Line 152-154, the description was carefully checked and revised. In Line 274-275, the sentence was revised accordingly (Line 165-169). The organic matter degradation ratio was based on the O₂ concentration which implied the O₂ consumption rate. Actually, the oxygen saturation probe was used to determine the pile oxygen concentration (Line 133-134).

 

 

8. C/N ratios during the composting process for the different treatments did not show noticeable reductions. In fact, the carbon/nitrogen ratio of the initial mixture of feedstocks should be between 30 and 35 to ensure the appropriate conditions for the microorganisms to decompose and transform the organic matter although values down to 25 can be used but with an increase in the overall time of composting, according to many authors. Moreover, when temperature increases, ammonia evaporation also increases and when C/N ratio is less than 18, the microorganisms transform the nitrogen in a higher degree, favoring its volatilization. In this case, the initial C/N ratios were in the range between 14 and 11. The C/N ratios at the end of the composting process should be in the range between 10 and 20 with the most stable composts falling in the lower end of this range. Considering these facts, the analysis level of the results obtained should be improved, especially if the authors consider the different components of the compost piles assessed. It is worthy to include the initial C/N ratios for each treatment in Table 2. In the introduction, it is stated that the C/N ratio of chicken manure is less than 5 (line 40), but the experimental value obtained for this same material was 15.1. How can this difference be explained?

Response: The corresponding discussion was shown in Line 239-241. We have carefully read reviewer’s suggestions, from the aspect of the C/N, negligible differences were found in the GHGs volatilization among all treatments (Table 3). In addition, previous studies have shown that the pre-treatment and storage methods of chicken manure raw materials can affect the of C / N ratio of chicken manure to a certain extent (Nahm et al., 2003).

Nahm KH. Evaluation of the nitrogen content in poultry manure. World's Poultry Science Journal. 2003;59:77-88.

 

9. In the supplementary material, provide the ANOVA or other results of the statistical analysis required to support some of the results presented in the text (e.g., when statistically significant differences were obtained between the treatments).

Response: Many thanks reviewer’s suggestion, standard errors were added in all the tables and figures.

 

10. The discussion of the data presented in Fig. 4 is somewhat confusing. The text should be improved to clearly present which data correspond to the treatments with the addition of vinasse and which to the treatments with the addition of mushroom bran (lines 276-279). How were the cumulative emissions calculated? (I consider that the citation of previous works that include some key methods is not enough; these methods or calculation procedures should be briefly described in the manuscript). The authors suggest in line 307 that the aerobic microorganisms can inhibit the nitrification process, but the data obtained show that nitrate can increase at the end of the composting process, i.e., the nitrifying bacteria increase their activity; how can the authors interpret this issue?

Response: As for the data shown in Figure 4, the text expression has been modified in the manuscript. The brief calculation method of cumulative emissions has been updated in the manuscript (Line 137-143). The nitrate content cannot reveal the real nitrification ratio, as the nitrate content also depend on the mass of the compost product which will decrease with the organic matter degradation (Shi et al., 2018).

Shi M, Wei Z, Wang L, et al. Response of humic acid formation to elevated nitrate during chicken manure composting[J]. Bioresource technology, 2018, 258: 390-394.

 

11. In the Conclusions section (or at the end of the Results and Discussion section), specific recommendations to perform the composting process considering the results obtained and the goals of the process itself should be included, along with some economic considerations. In particular, potential applications in candidate crops could be mentioned.

Response: Thanks, it was revised accordingly in Line 49-54.

 

12. Minor comments:

Line 34: remove the space before the percentage sign (and unify throughout the manuscript).

Response: Thanks, it’s revised through the manuscript.

 

Line 35: “Aerobic composting was an effective…” Why in past, is it not true for the present time? The same comment for line 53.

Response: It was revised in Line 36.

 

All the abbreviations should be deciphered as they first appear; some abbreviations of the methods are not deciphered.

Response: It was revised through the manuscript.

 

Table 1: there should be an annotation or remarks stating that the data are determined on a dry basis.

Response: It was revised in Line 100.

 

Line 101: change the multiplication sign for the units (it is not a dot).

Response: It was revised in Line 108.

 

Figure 1 and Table 3: all the abbreviations should be deciphered as remarks or in the captions.

Response: It was revised accordingly.

 

Line 234: “Good” and not “Well”.

Response: It was revised in Line 260.

 

Line 284: “reduced” and not “reduce”.

Response: It was revised in Line 327.

 

Lines 299-302: too much data; another way to present these results is suggested.

Response: Thanks, it was revised in Line 269-271.

 

Line 316: remove the minus signs.

Response: Thanks, but the minus signs was not found in Line 316.

Author Response File: Author Response.doc

Reviewer 2 Report

The submitted manuscript evaluates the effects of bulking agents (vinasse, mushroom bran, and tobacco powder) on composting maturity and greenhouse gas emissions in chicken manure composting. Although the findings of the manuscript are interesting, it requires significant improvement before further processing, especially in terms of data presentation, interpretation, and discussion.

Specific comments:

1. The language of the manuscript needs extensive editing.
2. The abstracts should be written following the guidelines of the journal.
3. L22-24: Need to mention the statistical significance.
4. Consider adding the practical implications in the abstract section.
5. L29: ‘output’, consider replacing with words like production or generation.
6. L30-32: This statement is not contradictory with the previous one, rather it indicates the issues related to excessive production of chicken manure.
7. L33-34: Livestock manure accounted for around 18% of the global greenhouse gas emissions. To be more specific, it would be better to mention the CH₄ and N₂O emissions from chicken manure as the whole paragraph focused on chicken manure.
8. L37: ‘on the other hand’- this is not in contradiction earlier statement.
9. L44: Consider replacing the word ‘outputted’.
10. The novelty statement should be more robust.
11. Table 1: Report the basis of estimation.
12. L110: ‘certain speed’- Mention the rate.
13. How about the statistical analysis?
14. Figure scales are overlapped.
15. The results need to be presented and discussed from a statistical point of view. How about the statistical difference among the treatments?
16. After completing the statistical analysis, rewrite the whole manuscript based on the statistical outcome.
17. The concluding remarks should be written more precisely, mentioning some general findings are not enough.

Author Response

Reviewer #2: 

The submitted manuscript evaluates the effects of bulking agents (vinasse, mushroom bran, and tobacco powder) on composting maturity and greenhouse gas emissions in chicken manure composting. Although the findings of the manuscript are interesting, it requires significant improvement before further processing, especially in terms of data presentation, interpretation, and discussion.

Response: The feasibility of the experimental method and further scientific discussion have been modified and marked in the manuscript.

 

Specific comments:

 

1. The language of the manuscript needs extensive editing.

Response: The language was further improved through the manuscript, and the revised places were marked in blue.

 

2. The abstracts should be written following the guidelines of the journal.

L22-24: Need to mention the statistical significance.

Response: Thanks, the description here aims to describe the reduction degree of emission amount of diverse gas but not to illustrate if there are significance between diverse treatments. Herein, statistical significance results were not shown here.

 

3. Consider adding the practical implications in the abstract section.

L29: ‘output’, consider replacing with words like production or generation.

Response: Thanks, it was revised in Line 30.

 

4. L30-32: This statement is not contradictory with the previous one, rather it indicates the issues related to excessive production of chicken manure.

Response: Thanks, it was revised in Line 31-32.

 

5. L33-34: Livestock manure accounted for around 18% of the global greenhouse gas emissions. To be more specific, it would be better to mention the CH4 and N2O emissions from chicken manure as the whole paragraph focused on chicken manure.

Response:  Thanks, it was revised in Line 30.

 

6. L37: ‘on the other hand’- this is not in contradiction earlier statement.

Response:  Thanks, it was revised in Line 37.

 

7. L44: Consider replacing the word ‘outputted’.

The novelty statement should be more robust.

Response: Thanks, it was revised in Line 45.

 

8. Table 1: Report the basis of estimation.

Response: All the data was determined by specific methods instead of estimation.

 

9. L110: ‘certain speed’- Mention the rate.

How about the statistical analysis?

Response: Thanks, it was revised in Line 108-109.

 

10. Figure scales are overlapped.

The results need to be presented and discussed from a statistical point of view. How about the statistical difference among the treatments?

Response: Many thanks reviewer’s comment. The results were achieved by evaluating the mean value, peak value and accumulative value of diverse treatments. Detailed discussion were shown in Line 165-170, Line 200-203, Line 238-241 and etc.

 

11. After completing the statistical analysis, rewrite the whole manuscript based on the statistical outcome.

Response: Many thanks for reviewer's recommendation. Actually, standard errors (SE) were added to each data, some SE was too small, and therefore cannot be identified from the figures. We have improved our manuscript discussion, such in Line 165-170, Line 287-289, Line 269-271 and etc.

 

12. The concluding remarks should be written more precisely, mentioning some general findings are not enough.

Response: Thanks, it was revised in Line 417-421.

 

Reviewer 3 Report

I think the paper is of interest, espetially for the discussion of the gas emissions from composting. Some sections need to be improved, the discussion, the materilas and coclusion, for example. The English language could be improved in some phrases. Please check the pdf for detailed comments. 

Also, here are more references that could help improving some parts:

for oxigen range 

Labance, S.E., Heinemann, P.H., Miller, F.C., Graves, R.E., Beyer, D.M., 2000. Evaluation of the effects of forced aeration during phase I maushroom substrate preparation and odor production and microbial heat generation. Proceedings of 2000ASAE Annaul International Meeting, Milwakee, Winsconsin, USA, July 9–12, 2000, pp. 1–20.  

Evolution of temperature

Insam, H., de Bertoldi, M., 2007. Microbiology of the composting process. In: Diaz, L.F., de Bertoldi, M., Bidlingmaier, W., Stentiford, E. Compost Science and Technology. Waste Managemnt Series, Elsevier, Amsterdam, the Netherlands. ISBN-13: 9780080439600. ISSN: 1478–7482, vol. 8, pp. 25–48.  

Nitrates in compost

Kuroda, K., Osada, T., Yonaga, M., Kanematu, A., Nitta, T., Mouri, S., kojima, T., 1996.

Emissions of malodorous compounds and greenhouse gases from composting swine feces. Bioresour. Technol. 56, 265–271.

Thompson, A.G., Wagner-Riddle, C., Fleming, R., 2004. Emissions of N2O and CH4 during the composting of liquid swine manure. In: Environmental Monitoring and Assessment, Kluwer Academic Publishers, The Netherlands, vol. 91, pp. 87– 104.  

Nitrification denitrification in compost

Maeda, K., Hanajima, D., Toyoda, S., Yoshida, N., Morioka, R., Osada, T., 2011. Microbiology of nitrogen cycle in animal compost. Micorbial Biotechnol. 4 (6), 700–709.

Maeda, K., Toyoda, S., Hanajima, D., Yoshida, N., 2013. Denitrifieras in the surface zone are primarly responsible for the nitrous oxide emission of dairy manure compost. J. Hazard. Mater. 248–249 (2013), 329–336.

Szanto, G.L., Hamelers, H.V.M., Rulkens, W.H., Veeken, A.H.M., 2007. NH3, N2O and CH4 emissions during passively aerated composting of straw rich pig manure. Bioresour. Technol. 98, 2659–2670.

Sun, X., Lu, P., Jiang, T., Schuchardt, F., Li

Best Regards

Comments for author File: Comments.pdf

Author Response

Reviewer #3: 

I think the paper is of interest, especially for the discussion of the gas emissions from composting. Some sections need to be improved, the discussion, the materilas and coclusion, for example. The English language could be improved in some phrases. Please check the pdf for detailed comments.

Response: Many thanks for reviewer's valuable comments, we have revised accordingly in Line 30-31, Line 45-48, Line 50-63 and etc.

 

Also, here are more references that could help improving some parts.

Response: Many thanks for reviewer’s recommendation. The recommended references were all cited properly.

Round 2

Reviewer 1 Report

The main issues were modified, but some recommendations were not appropriately taken into account in the last version of the manuscript.

I don’t feel that the authors have thoroughly checked the English level of the confusing sentences I identified in the first version of the manuscript (lines 45-51, 54-55, 62-63, 67, 156-158, 162-163, 357-358). In general, the English level of the paper must be improved in order to be published in Processes journal.

I insist that it is worthy to include the initial C/N ratios for each treatment in Table 2. In the introduction, it is stated that the C/N ratio of chicken manure is less than 5 (line 40), but the experimental value obtained for this same material was 15.1. The answer should be included in the manuscript.

I insist that, in the supplementary material, the ANOVA or other results of the statistical analysis required to support some of the results presented in the text should be included. In fact, two of the tables include the standard deviations, but this is not enough to demonstrate that an appropriate statistical analysis was conducted (actually, there are not error bars in the graphics, but it is difficult to show them because of the space limitations; therefore, an appendix with the ANOVA results is acknowledged).

In the Conclusions section (or at the end of the Results and Discussion section), no economic considerations were included.

Minor comments: Correct the following units: L·kg-1·DM·min-1 (apply superscripts).

 

Author Response

Reviewer’s comments:

The main issues were modified, but some recommendations were not appropriately taken into account in the last version of the manuscript.

Response: Many thanks for reviewer’s valuable comment again, careful revision was conducted accordingly.

 

1. I don’t feel that the authors have thoroughly checked the English level of the confusing sentences I identified in the first version of the manuscript (lines 45-51, 54-55, 62-63, 67, 156-158, 162-163, 357-358). In general, the English level of the paper must be improved in order to be published in Processes

Response: Corresponding revisions were made in Line 43-47, Line 65-68, Line 169-171, Line 370-372.

 

2. I insist that it is worthy to include the initial C/N ratios for each treatment in Table 2. In the introduction, it is stated that the C/N ratio of chicken manure is less than 5 (line 40), but the experimental value obtained for this same material was 15.1. The answer should be included in the manuscript.

Response: The initial C/N ratios for each treatment were shown in Table 3. The reason for why the experimental value obtained for this same material was 15.1 was given in Line 94-98.

 

3. I insist that, in the supplementary material, the ANOVA or other results of the statistical analysis required to support some of the results presented in the text should be included. In fact, two of the tables include the standard deviations, but this is not enough to demonstratethat an appropriate statistical analysis was conducted (actually, there are not error bars in the graphics, but it is difficult to show them because of the space limitations; therefore, an appendix with the ANOVA results is acknowledged).

Response: ANOVA was conducted (Line ) and the corresponding results were shown in Table 3. Actually, the GHGs were continuously collected through the gas collection system, and each treatment was conducted in only one 60-L composting reactor which was same in our previous study (Zhang et al., 2020; Zhang et al., 2021), thus the error bars was not shown.

Zhang, B.; Fan, B.; Hassan, I.; Peng, Y.; Ma, R.; Guan, C.-Y.; Chen, S.; Cui, S.; Li, G. Effects of bamboo biochar on nitrogen conservation during co-composting of layer manure and spent mushroom substrate. Environmental Technology. 2021, 1-24.

Zhang, B.; Xu, Z.; Jiang, T.; Huda, N.; Li, G.; Luo, W. Gaseous emission and maturity in composting of livestock manure and tobacco wastes: Effects of aeration intensities and mitigation by physiochemical additives. Environmental Technology & Innovation. 2020, 19, 100899.

 

4. In the Conclusions section (or at the end of the Results and Discussion section), no economic considerations were included.

Response: The mushroom bran, tobacco powder and vinasse bran were all free of charge, as they are the organic waste in local area. Herein, addition of these organic waste as bulking agents can save the cost of the compost feedstock, e.g., addition of 20% bulking agent can save 20% cost of the compost feedstock (chicken manure). The above illustration was added in Line 401-405.

 

5. Minor comments: Correct the following units: L·kg-1·DM·min-1 (apply superscripts).

Response: Thanks, and it’s corrected in Line 110.

Reviewer 2 Report

The reviewer appreciates the authors’ efforts to improve the quality of the manuscript. However, there are still some issues remaining in the manuscript.

1. In reply to the query regarding statistical significance, the authors’ mentioned ‘the aim of this study was to describe the reduction degree of emission amount of diverse gas from chicken manure. However, in the abstract they stated that 'the 10% mushroom bran combined with 5% tobacco powder was the optimal combination for simultaneously improving the maturity and reducing greenhouse gas emission in chicken manure composting.'- which again arises the question of statistical significance.
2. In introduction, ‘Improper process’ should be ‘Improper processing’. such issues indicate that the writing still needs further significant improvement. It is highly recommended to use professional language editing service
3. The authors were asked to mention CH₄ and N₂O emissions from chicken manure. Although they claimed the information was included in the revised manuscript, no such information was found.
4. ‘On the other hand, a large number of ammonia and GHGs released in the process of aerobic composting, on the one hand, cause serious atmosphere pollution, and on the other hand, the loss of nitrogen and carbon lead to the decline of the quality of the final composting products.’ This statement is more confusing than the previous one. Consider rewriting the statement as: ‘However, a significant amount of ammonia and GHGs released during aerobic composting which causes serious atmospheric pollution and the loss of nitrogen and carbon leads to the decline of the quality of the final composting products [5].’
5. ‘After tobacco powder was added in CM compost, the porosity of pile porosity increased’- write this statement properly.
6. Statistical point of view is still underrepresented in the manuscript.

Author Response

Reviewer’s comments:

The reviewer appreciates the authors’ efforts to improve the quality of the manuscript. However, there are still some issues remaining in the manuscript.

Response: Many reviewer’s valuable comments, we have further improved manuscript.

 

1. In reply to the query regarding statistical significance, the authors’ mentioned ‘the aim of this study was to describe the reduction degree of emission amount of diverse gas from chicken manure. However, in the abstract they stated that 'the 10% mushroom bran combined with 5% tobacco powder was the optimal combination for simultaneously improving the maturity and reducing greenhouse gas emission in chicken manure composting.'- which again arises the question of statistical significance.

Response: The statistical analysis for pH, EC, E4/E6, C/N and GI was conducted and results were shown in Table 3. However, the GHGs were continuously collected through the gas collection system, and each treatment was conducted in only one 60-L composting reactor which was same in our previous study (Zhang et al., 2020; Zhang et al., 2021), thus the statistical analysis for gas emission was not performed.

Zhang, B.; Fan, B.; Hassan, I.; Peng, Y.; Ma, R.; Guan, C.-Y.; Chen, S.; Cui, S.; Li, G. Effects of bamboo biochar on nitrogen conservation during co-composting of layer manure and spent mushroom substrate. Environmental Technology. 2021, 1-24.

Zhang, B.; Xu, Z.; Jiang, T.; Huda, N.; Li, G.; Luo, W. Gaseous emission and maturity in composting of livestock manure and tobacco wastes: Effects of aeration intensities and mitigation by physiochemical additives. Environmental Technology & Innovation. 2020, 19, 100899.

 

2. In introduction, ‘Improper process’ should be ‘Improper processing’. such issues indicate that the writing still needs further significant improvement. It is highly recommended to use professional language editing service.

Response: It’s corrected and the manuscript language was overall improved by native speaker.

 

3. The authors were asked to mention CH₄ and N₂O emissions from chicken manure. Although they claimed the information was included in the revised manuscript, no such information was found.
   Response: The discussions for CH₄ and N₂O emissions from chicken manure were shown in Line 296-Line 310 and Line 317-335 respectively.
   
   
4. ‘On the other hand, a large number of ammonia and GHGs released in the process of aerobic composting, on the one hand, cause serious atmosphere pollution, and on the other hand, the loss of nitrogen and carbon lead to the decline of the quality of the final composting products.’ This statement is more confusing than the previous one. Consider rewriting the statement as: ‘However, a significant amount of ammonia and GHGs released during aerobic composting which causes serious atmospheric pollution and the loss of nitrogen and carbon leads to the decline of the quality of the final composting products [5].’
   Response: Much appreciation for reviewer’s invaluable suggestion, it’s corrected in Line 35-38.
   
   
5. ‘After tobacco powder was added in CM compost, the porosity of pile porosity increased’- write this statement properly.
   Response: It’s corrected in Line 245-246.
   
   
6. Statistical point of view is still underrepresented in the manuscript.

Response: Thanks, It’s corrected in Table 3 and Line 159-162.

Round 3

Reviewer 2 Report

After the revision, the manuscript as a whole is now more scientifically sound and logically described.

Author Response

审稿人 #2 ：

修改后，整个手稿现在更科学、更合乎逻辑。

回复：非常感谢审稿人的推荐。手稿中的更改已用红色标记（第 34、55、144 和 405 行）。

Author Response File: Author Response.doc