Utilization of Thermophilic Aerobic Oxidation and Electrocoagulation to Improve Fertilizer Quality from Mixed Manure Influent

Round 1

Reviewer 1 Report

Comments:

1. Your introduction is really laconic. With such a poor justification for the research, the lack of information about the achievements of other scientists on similar topics, I don’t see a good reason for implementation of the result obtained. The aim of the study was also laconic. Work on the introduction, please and use the literature cited: you have over 70 items.

2. Diagrams, photos and  charts are so small and illegible. Enlarge them, please.

3. Formulate a discussion of the results, please - this chapter is missing in your article and present the implementation perspectives of the proposed method.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

I have read the manuscript and I have the following comments and required suggestions.

1. The title of the paper must be revised to become a clear statement of the goal of the paper.  As it stands, the reader is not really sure what the primary purpose of the paper is.
2. There are many editorial changes needed to improve the clarity of the paper throughout. Perhaps a editorial service could help.
3. The abstract assumes that the reader is familiar with term "maturity " as used by the authors. As it turns out it refers to a germination test developed by an author. I recommend eliminating such terms in the abstract. You will define them later in the paper.
4. From the abstract and the remainder of the paper the authors lead the reader to think that swine manure is full of toxic pollutants. In fact, the only element that was tested for that is not a major or minor plant nutrient is Cr. All of the others are required by plants in small amounts.  Please change the tone of the entire paper. The main value of this process is to remove excess amounts of P, Cu, Ni, and Zn from manure and to decrease the Cr content (typically small in content).
5. It was not till I read the methods section that I learned that some type of food waste was included.
6. The Introduction must be revised to explain the actual problem that this process is trying to solve. What are the important characteristics of the particular waste stream? What are the nutrients and elements that are causing a problem with using swine manure and food waste as a fertilizer substitute? How will this process address the problem? Then based on this focus of the goal, please end the Introduction with a clear, explicit statement of the objective or objectives.  As it stands, all the Introduction tells the reader is that pollutants are contained in swine manure and a well known biological an electrochemical processes can remove them. 
7. The Materials and Methods are too brief. 
8. Figure 1 show the reader very little. The two processes need to be described in more detail. Many different steps in the TAO process are mentioned far too quickly. The pH adjustment step has almost no details. Figure 1 does not add anything since nothing can be seen in the drawing and it has no labels or dimensions. 
9. The description of the electrocoagulation process is also way too short.  This requires more detail. 
10. The goal of the methods section is to provide enough detail to allow another researcher to replicate your study in the future. You have not met that goal.
11. The Sample Analysis section is also too short. You have given no reasons for the plant nutrients  and elements selected. 
12. You use the term removal efficiency in equation 7. This should be called concentration reduction. If you can provide results based on mass (CV) then removal efficiency would be appropriate.
13. You gave no description of the food waste and the swine waste that were combined. Why did you choose the proportions that you used for your mixture?
14. How many replications were performed? What were the statistical methods used? These all must be in Materials and Methods.
15. You referenced your paper on LFGI. However, you told the reader nothing about how this was carried out in this study. We must have the details on this. What was used exactly for germination trials? How?
16. The Results section is also lacking in information and details.
17. I suggest the following order. (1) Present detailed information concerning the composition of the food waste used, the swine waste used, and the composition of the mixture. Give means and standard deviations for each item measured. How does the composition of the swine manure used compare to what is encountered on Korean Swine farms? What precludes using the swine manure from being applied to cropland based on an agronomic rate for plant available-N, P2O5, K2O? That is point out explicitly the problem that your two step treatment process will address. (2) Provide the complete results for step 1 - TAO. Explain what it removed or added and why (you have some of this related to nitrate) using the concentration reduction (CR) or mass reduction (RE) if you can. Just use a well designed table just for TAO. Figure 3 added nothing.  I am not sure that we call changes in pH and  Then explain if the first step addressed the main problem.  Explain that the effluent of TAO became the influent for step 2 - the EC treatment. Do not include the LFGI results here at all. They need a separate section. (3) Provide all of the results for the two step process in the next section. Still do not include LFGI yet. For clarity, provide another well designed table that shows the CR for TAO+EC. Did the two step process address the main problem? Did it remove things that the user would rather not remove? Yes it did. I generally want all the N. It is very valuable. Where did the N and P and other elements go? Is there a concentrated waste stream that can be used or did you just create a concentrated and more hazardous waste?  Why would using this process be better than just applying the waste to cropland at the agronomic rate for P2O5? As the paper is written, I have no idea why I would ever want to implement this two-step treatment process. (4) Provide the complete results for the LFGI study in this final section. I should be able to refer back to the Materials and Methods to understand what was done and now why it is important. Currently, the paper is way too short. Did you try to germinate seeds in pure manure or pure treated manure? In practice no one would ever do this. Therefore you need to add much more information and detail on this.
18. Please stop calling fertilizer such as N, P, K, and minor nutrients pollutants. They are only pollutants if they are in excess or are in water.
19. Figure 4 adds very little. Well designed tables will do much more. Eliminate Figure 4.
20. Revise the conclusions to address each of the explicit objectives that should be at the end of the Introduction.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript entitled “Combined Application of the Thermophilic Aeration Oxidation and Electrocoagulation to Improve the Liquid Fertilizer Quality Based Swine Manure” submitted to agronomy needs corrections and improvements. Below are major and minor comments for the improvement of the manuscript.

1. English language revision is needed.
2. It will be better to select key words that are not mention in the title.
3. Section 3 should be results and discussion as the authors not only presented their findings.
4. Figure 3 needs correction. Remove the units in the X axis of physical parameters (mS/cm and %).
5. The authors reported related to seed germination. Did you test seed germination?
6. The figures shown that the authors make comparison among three methods (MI, TAO, and EC). There is no explanation on MI. Also, there is some confusion in the Table 3, where is MI here? Is it influent? If yes, unify it.
7. The authors should present the results based on the obtained data illustrated in the figures and Tables. They claimed that the total reduction efficiency by the combination of TAO and EC led to a 35% conductivity decrease; however, conductivity is reduced in the EC.
8. The authors presented the same data and values of Table 3 in figures. The Figures look unnecessary and duplicated.
9. Check the references thoroughly and unify them based on the guidance of the journal.

Author Response

please check the attached file. 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

This version is much more clear. Thank you. I was able to understand the seed germination test and results much better.

The introduction shows that the authors view the concentrations of plant nutrients and metals to be problematic. The reader is left with the impression that the two materials, liquid swine waste (LSW) and food waste AD effluent (FWAD) could not be land applied without treatment.  I have attached a pdf file that shows land application calculations for 112 kg N/ha, 45 kg P2O5/ha, and 45 kg K2O/ha. I calculated the liquid application rate based on providing 112 kg N/ha and then looked at all other nutrient application rates. I just did this for LSW and the LSW and FWAD mix. I would have no problems using LSW as a fertilizer substitute. After the LSW results it was obvious that the FWAD was much stronger than LSD. 

I also noted that sodium was not measured and would be key component in EC. However K is also associated with high EC because it is often in KCL form. 

The land application calculations with the mix prior to treatment would also not present a problem. 

The Introduction needs to be greatly improved. The purpose of the LSW is to dilute the FWAD to make it easier to use as a fertilizer substitute. You should be testing mixing with mixing and treatment. 

The germination test is extreme. If you look at the application calculations it should be obvious that the soil environment will not be so harsh on the seeds. Such a test only correlates to field conditions in extreme cases. At best, it is an index. 

I also saw several typos, but I am more concerned with the extreme tone of the introduction that also demonstrates lack of understanding concerning the fact that the mass of nutrient applied to a field is far more important than the concentration. Since this is for Agronomy I think the treatment should be evaluated based on the impact on land application.

Also - the fact that EC was reduced more by mixing than by your two step treatment is the main thing. Since Na was not measured the results and conclusions should state that and that EC is your only general indicator of NaCl.

Comments for author File: Comments.pdf

Author Response

Please check the attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

All my concerns have been solved. I have no more comments.

Author Response

Thanks for your help