An Experimental Study of Paddy Drainage Treatment by Zeolite and Effective Microorganisms (EM)
Round 1
Reviewer 1 Report
Dear Author
Effects of Zeolite and Effective microorganisms (EM) on Water Quality of Eco-ditches receiving Paddy Drainage
Using zeolite and EM in removing nutrients (like N, P) from the water is important approach, which some workers focused on it recently to avoid or reduce the risks of eutrophication phenomena!
It could notice that about the half or list of refs. In this MS includes the removing nutrients (mainly N) by zeolite in wastewater, that means this is common idea!
General comments:
1- About the novelty, similar published articles handled this idea like
Xiaotian Li et al. (2020). Enhancing Nitrogen and Phosphorus Removal by Applying Effective Microorganisms to Constructed Wetlands. Water 2020, 12, 2443; doi:10.3390/w12092443
2- For the Keywords, it should avoid any word already mentioned in the title?
3- The author mentioned that “EM bacteria, nitrifying bacteria and 84 denitrifying bacteria” please clarify, which species??
4- The period of this experiment is short (from November 1 to November 9, 2021), I think at least 2 weeks to be able to recommend soothing in this study??
5- The soil total nitrogen 86 of 1.790 g·kg-1 and total phosphorus of 0.430 g·kg-1, please check?
6- Where the pH and EC values of used soil?
7- Any abbreviation must first write in the text in details for the first time and then use them like SDD and CDD???
8- There is no “pure soil,” this is natural soil, please use the correct term like control?
9- Using the “The 2000 mL standard measuring cup was selected for the experiment” is very limited, how can author will give a recommendation? It should use some thing similar to the real ditches?? What was happened in this very limited beaker, definitely can not generalize to be suitable for the real study? May be building or Constructed ditcher is the best for generalization of getting results?
10- One more problem in design this experiment, in the real work for paddy cultivation, many nutrients will be existed not only N or P? and the interactions among these nutrients and used soil will be happened?? Soil is not inert system??? And finally, the results will be different???
11- Therefor, the field NOT Lab experiments are preferable, especially the role of zeolite or EM in this polluted media already studied???
Author Response
please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The comment file is attached below
Comments for author File: Comments.pdf
Author Response
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Author Response File: 
Author Response.docx
Reviewer 3 Report
Dear Authors
In the work Effects of Zeolite and Effective microorganisms (EM) on Water Quality of Eco-ditches receiving Paddy Drainage, the authors analyzed the properties of zeolite and microorganisms in the process of reducing certain pollutants in laboratory conditions. The absorption and filtration properties of zeolites are generally known and recognized. In this case, the experiment is interesting and related to ecological ditches. In my opinion, the selected variants of zeolite and EM application as well as the methodology of laboratory experiments are correct. The results of the analysis are as expected. The use of zeolite and EM in ecological ditches could significantly improve water quality. I believe that the disadvantage of the conducted research is the lack of a field experiment. It seems that the use of natural zeolite in ecological ditches in field conditions may be very difficult. Mainly due to the possibility of obtaining material in the region. The lack of research in the field conditions of ecological ditches does not answer many questions. In the case of laboratory studies, the natural properties of soil or soil were not taken into account, or the methodology did not describe it in detail. Soil is a complex matter containing many components along with a sorption complex. These properties also have an impact on the reduction of indicators, filtration or sorption. The work needs improvement in its current form, in the absence of field trials of convincing appeals.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
The authors based the study on determination of the impact of additives: natural zeolite and effective microorganisms (EM) to eco-ditch in order to improve the quality of received water from paddy drainage.
The work provided an evaluation of the efficiency of different combinations on the nitrogen removal and the possibility of using zeolite and EM bacteria in eco-ditches; and analysis of the variation of pH, dissolved oxygen (DO), ammonium nitrogen concentration (NH+4 -N) and nitrate nitrogen concentration (NO-3-N) from paddy drainage water.
To improve the manuscript, authors should consider the following recommendations:
1- Authors indicated only that EM are based on nitrifying and denitrifying bacteria. They did not indicate the composition and the status (initially active or inactive microorganisms) of effective microorganisms. Information about the main bacterial species or genera have to be included to relate the effects obtained to specific bacterial strains.
2- Effective microorganisms were loaded at which concentration??
3- Table 1: indication for combinaition (Z5; Z10; Z15 xEM) must be corrected: soil instead of soli
4- Authors used statistical analysis to show the difference level between the obtained results. However, no indication was provided in Figure 2 to state the significant differences.
5- Table 3: more indication must be provided to give comprehensible and indicative illustration. For example:
- Values are presented as (means SE) or…
- The asterisk *, ** or *** and ns indication??
- Different letters a, b, c added to the results indication?
6- The legend of figure 3 related to the correlations have to be more understandable:
- Color indications??
- Circle size?
- Indicated values?
7- Authors must justify the choice of 9 days as experiment duration?
8- Reference list: some reference details have to be indicated as required by the journal instructions. Please revise reference: 23, 24, 27 and 30.
9- The manuscript require language revision to ovoid several miss formulated sentences and mistakes.
Author Response
Please see the attachement.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I check the revised MS and I did not find new concerning the wrong design of this experiment as I said in the first round:
Using the “The 2000 mL standard measuring cup was selected for the experiment” is very limited, how can author will give a recommendation? It should use some thing similar to the real ditches?? What was happened in this very limited beaker, definitely can not generalize to be suitable for the real study? May be building or Constructed ditcher is the best for generalization of getting results?
thanks!
Author Response
Thank you very much for your time involved in reviewing the manuscript. We also appreciate your clear and detailed feedback and hope that the explanation has fully addressed all of your concerns.
The main subject of this research is to find out the effects of zeolite and EM on nitrogen removal of paddy drainage. It's only a lab experiment, admittedly, but the ratio between the beaker and real ditch fit together. More details about the methodology were described in Lab Experimental Design: 2000 mL standard measuring cup was selected to simulate the static condition of stored drainage in paddy ditch under laboratory conditions. Bottoms of the cups were filled with 0.4 kg substrates at different mass ratio in Table 1 (soil bulk density 1.40 g·cm-3) to simulate the different ditches. According to ratio of drainage ditch section size to water storage, 1200 mL simulated paddy field drainage was added to the measuring cup respectively (lines 410- 415, page 3).
Besides, statements about the limitations of lab experiment are also added in Conclusions: It should be noted that the conclusions were based on laboratory studies, which was subject to some qualifications (lines 1218- 1220, page 10).
As reviewer’s comments, this lab experiment can not to be generalized as a suitable research for the real study, but the method could be referred to as eco-ditch design. Furthermore, field experiments would be conducted to provide more data for eco-ditch building. Soil properties and other nutrient indicators could be further analyzed and considered in future field experiment. Besides, factors such as cultivation patterns and fertilizer managements would affect the interactions among nutrients and used soil in actual production, but the method could be referred to as eco-ditch design (lines 1220- 1223, page 10).
Reviewer 3 Report
Dear Authors
Thank you for considering the suggestion. Text format needs to be improved.
Author Response
Thank you very much for your time involved in reviewing the manuscript.
We have carefully revised the text format according to Manuscript Submission & Instructions for Authors and sustainability-template.
Author Response File: Author Response.docx
Reviewer 4 Report
Authors provided a cover letter with answers about each indicated point. However, the revised manuscript (pdf file) structure and form did not allow to track the made changes (mainly pages from 6 to 18).
I propose to receive more structured revised version of the manuscript.
Author Response
We feel sorry for the previous revised manuscript. According to reviewer’s comment, we have provided a more structured revised manuscript named revised manuscript_1716472(red) (highlight the changes by using red text).
Author Response File: Author Response.docx
Round 3
Reviewer 1 Report
There is nothing new because it is the same experiment design that has not changed. It is a design error because this is not a preliminary experiment in this subject, but was preceded by many studies. It is illogical to use a 2-liter beaker to conduct the experiment instead of carrying it out naturally. The design of the experiment is wrong. The research remains wrong. It remains rejected even if it is done. Reviewed for the millionth time, thank you
Author Response
Sorry for the confusion, we agree that using 2-liter beakers to simulate the paddy ditches seems illogical. However, we want to investigate whether zeolite and EM would remove the excess nitrogen from paddy drainage water. And to eliminate the effects of other substances on the drainage water which would remove nitrogen in the real ditches, we used beaker experiments, and just observed the effects of zeolite and EM on paddy drainage water.
Results showed that the application of zeolites and EM exerted dramatically increases of NH+ 4-N and NO- 3-N removals from paddy drainage water, via the rapid adsorption in previous stage and bacterial metabolism in latter stage. Next time, we will combined other factors like soil properties of ditches, schedules of irrigation and drainage, fertilization, precipitations, etc.
According to your comments, we added more information in Introduction and Lab Experimental Design to address the reason of beaker experiment (page 2, lines 76- 88; page 3, lines 155- 157). Furthermore, we modified the study limitations and research proposals in Conclusions (page 10, lines 393 -397).
page 2, lines 76- 88:
Previous studies demonstrated the potential to adopt zeolites or EM on water treatment. Given the high nitrogen concentration of paddy field drainage, zeolite and EM bacteria may be important amendments to eco-ditch substrates. However, eco-ditch systems are complex matters containing many components, such as macrophytes, substrates, and microbes [22]. The water residence and biofilm development on macrophytes [23], nutrients content of sediment, water and plants [24] and sorption properties of other components have an impact on the nutrient cycling of ditch system, which may interfere with zeolite or EM’s ability to remove the excess nitrogen from paddy drainage in the real ditches.
For this reason, a laboratory experiment was designed to eliminate the effects of other substances on the drainage water which would remove nitrogen in the real ditches. This research just focused on the effects of zeolite and EM bacteria on water quality from paddy drainage.……
- Nsenga Kumwimba, M.; Meng, F.; Iseyemi, O.; Moore, M.T.; Zhu, B.; Tao, W.; Liang, T.J.; Ilunga, L. Removal of non-point source pollutants from domestic sewage and agricultural runoff by vegetated drainage ditches (VDDs): Design, mechanism, management strategies, and future directions. Sci Total Environ 2018, 639, 742-759, doi:10.1016/j.scitotenv.2018.05.184.
- Soana, E.; Balestrini, R.; Vincenzi, F.; Bartoli, M.; Castaldelli, G. Mitigation of nitrogen pollution in vegetated ditches fed by nitrate-rich spring waters. Agriculture, Ecosystems & Environment 2017, 243, 74-82, doi:10.1016/j.agee.2017.04.004.
- Wang, J.; Chen, G.; Fu, Z.; Song, X.; Yang, L.; Liu, F. Application performance and nutrient stoichiometric variation of ecological ditch systems in treating non-point source pollutants from paddy fields. Agriculture, Ecosystems & Environment 2020, 299, 106989, doi:10.1016/j.agee.2020.106989.
page 3, lines 155- 157:
In order to eliminate the influences of other factors on the drainage water, only natural zeolite (Z) and Effective Microorganisms (EM) were manipulated in this beaker experiment.
page 10, lines 393 -397:
It should be noted that the conclusions were based on laboratory studies, which was subject to some qualifications. During the experiment, this study ignored the effects of some indicators such as soil properties of ditches, schedules of irrigation and drainage, fertilization in the real ditches on the drainage water quality. Therefore, further studies of field experiments should be conducted.
