Removal of Reactive Yellow 86 from Synthetic Wastewater in Lab-Scale Constructed Wetlands Planted with Cattail and Papyrus
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe novelty of this study is low, but its results for dye removal from wastewater by constructed wetlands may have a potential to benefit others.
Some advices
1) The introduction and methodologies (with citing other references) should be corrected to make it easy and clear understanding, and easy for citation
2) Experimental results and explanation must be reasonable and compared with other similar studies in this field with citing those most related articles
3) Citations should be well organized to justify the key statements.
Comments on the Quality of English LanguageGood advices to polish the manuscript with native English writer
Author Response
Thank you for your kind advices.
1) The introduction and methodologies (with citing other references) should be corrected to make it easy and clear understanding, and easy for citation.
For clear understanding, the citation style slightly improved On. L23, 29.
2) Experimental results and explanation must be reasonable and compared with other similar studies in this field with citing those most related articles.
As far as we know, no report of the relevant literature describes RY86 removal by CWs (L53). Similar researches with our research (dye removal in CWs) were cited as Ref. 10-14.
3) Citations should be well organized to justify the key statements.
For justify our methodology and results the citation Ref. 16,17, 28, 29 were added.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper is well-written, and the results are thoroughly described. The methodology is sound, and the findings are significant. However, some sections could benefit from further clarification.
The introduction (literature review) lacks a clear statement of previous works on the removal of RY86.
The results are presented clearly, with appropriate use of tables and figures. However, the discussion could be expanded to include a comparison with previous studies.
The discussion provides a good interpretation of the findings but would benefit from a more critical analysis of the study's limitations. Please discuss how these limitations might affect the results and their generalizability.
The conclusion effectively summarizes the main findings but should also address the study's implications for future research and practice.
Author Response
1) The introduction (literature review) lacks a clear statement of previous works on the removal of RY86.
Reportedly, RY86 is degraded by photolysis using multi-structured Fe2O3 nanoparticles as catalysts [15, 16,17], the photo-Fenton process [18], electrochemical treatment [19], and laccase released by Bacillus safensis [20]. I added two citation, 16 and 17. As far as we know, no report of the relevant literature describes RY86 removal by CWs.
2) The results are presented clearly, with appropriate use of tables and figures. However, the discussion could be expanded to include a comparison with previous studies.
As far as we know, no report of the relevant literature describes RY86 removal by CWs (L213-214). Discussion was expanded for future research on degradation pathway and toxicity assay of RY86. L255-260.
3) The discussion provides a good interpretation of the findings but would benefit from a more critical analysis of the study's limitations. Please discuss how these limitations might affect the results and their generalizability.
Regrettably, the mineralization efficiency for RY86 in the CWs remained unknown (L244). Phylogenetic identification and characterization of RY86-decolorizing microorganisms found in this study will be helpful for further elucidation of decolorization mechanisms in the CWs. The biodegradation pathway of RY86 by microorganisms should be elucidated because toxic aromatic amines can be accumulated in the azo-dye degradation process. These were added on L255-260.
4) The conclusion effectively summarizes the main findings but should also address the study's implications for future research and practice.
These finding will contribute to establish design and operation of CWs for cos-effective treatment of dye wastewater. This implication was added on L279-280.
Reviewer 3 Report
Comments and Suggestions for AuthorsThis paper reported Removal of Reactive Yellow 86 from synthetic wastewater in lab-scale constructed wetlands planted with cattail and papyrus. After carefully review, some issues still need to be addressed before publication.
Special comments:
1. The innovation should be further improved.
2. The degradation intermediates of Reactive Yellow 86 should be addressed.
3. The degradation pathways of Reactive Yellow 86 should be addressed.
4. The mineralization rate of Reactive Yellow 86 should be addressed.
5. The removal performance of Reactive Yellow 86 by this treatment should be compared with previous studies.
6. The tables and figures should be improved.
7. Discussion depth should be improved.
Author Response
1. The innovation should be further improved.
As far as we know, no report of the relevant literature describes RY86 removal by CWs (L54-55).We found that Papyrus and cattail, especially the former, are suitable plants for CWs intended to treat RY86-containing wastewater (abstract).
2. The degradation intermediates of Reactive Yellow 86 should be addressed.
3. The degradation pathways of Reactive Yellow 86 should be addressed.
As answers to comments 2 and 3, azo dyes can be degraded by azo reductases for the reducing azo bond (-N=N-) by anaerobic/anoxic bacteria [25] and lignin peroxidase, laccases, and peroxidases of fungi [26, 27]. The biodegradation pathway of RY86 should be elucidated in our next study because toxic aromatic amines can be accumulated in the azo-dye degradation process. This was added L252, 255-260.
4. The mineralization rate of Reactive Yellow 86 should be addressed.
Regrettably we could not evaluate the mineralization rate or efficiency. We tried to measure total organic carbon (TOC) concentration in effluent. It was below 10 mg/L but it must contained root exudate of the plant. The mineralization efficiency for RY86 in the CWs remained unknown. It was added on L244.
5. The removal performance of Reactive Yellow 86 by this treatment should be compared with previous studies.
As far as we know, no report of the relevant literature describes RY86 removal by CWs (L54-55). It cannot be compared with other removal processes, such as photodegration.
7. The tables and figures should be improved.
Please give us specific comments. Reviewer No.2 gave us a comment that "The results are presented clearly, with appropriate use of tables and figures".
8. Discussion depth should be improved.
Discussion was expanded on L255-260.
Reviewer 4 Report
Comments and Suggestions for AuthorsThis manuscript describes the removal of reactive yellow 86 from synthetic wastewater in lab-scale constructed wetlands planted with cattail and papyrus. The results are very important in environmental protection field, and support the main conclusions. The manuscript is well organized and MINOR revisions are requested before acceptance. My comments are below:
1. What is the exact meaning of lab-scale? What is the evidence and basis?
2. Data lists are requested for the results in Fig.2.
3. What functional groups are the two observed absorption band for in Fig.3.
4. More discussions should be given based on Fig. 6.
5. More evidence and discussions should be given to explore the removal mechanism.
Author Response
1. What is the exact meaning of lab-scale? What is the evidence and basis?
The word “lab-scale” was revised to “laboratory-scale”. It often expressed as lab-scale. The CWs used in this study was very small and set in a greenhouse (L 10.7 cm × W 8.8 cm × H 25.0 cm). Ref. 13 also used the word “lab-scaled constructed wetland”.
2. Data lists are requested for the results in Fig.2.
Data on Figure 2 was uploaded as non-published Material.
3. What functional groups are the two observed absorption band for in Fig.3.
When a molecule of azo dyes has strong electron-withdrawing and electron-donating groups, the peak generally shifts to longer wavelengths. Other researchers also evaluate RY86 concentration by A416, but a reason for two peaks have not been clearly mentioned.
4. More discussions should be given based on Fig. 6.
It was added that “phylogenetic identification and characterization of RY86-decolorizing microorganisms found in this study (Figure 6) will be helpful for further elucidation of decolorization mechanisms in the CWs.” On L 255-260. Actually it will be reported in our next paper.
5. More evidence and discussions should be given to explore the removal mechanism.
Regrettably our experimental evidence is limited but we will characterize the decolorizing microorganisms and the biodegradation pathway of RY86 should be elucidated because toxic aromatic amines can be accumulated in the azo-dye degradation process [28, 29]. This was added on L259-260.
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsThis paper reported Removal of Reactive Yellow 86 from synthetic wastewater in lab-scale constructed wetlands planted with cattail and papyrus. After carefully review, some issues still need to be addressed before publication.
Special comments:
1. The innovation should be further improved.
2. The degradation intermediates of Reactive Yellow 86 should be addressed.
3. The degradation pathways of Reactive Yellow 86 should be addressed.
4. The mineralization rate of Reactive Yellow 86 should be addressed.
5. The removal performance of Reactive Yellow 86 by this treatment should be compared with previous studies.
6. The tables and figures should be improved.
Author Response
You gave me six questions which were monotonously same with the first round. My answers might be insufficient for your questions , but I have already revised it for Questions 1-6.
For Q1. I have already answered that no report of the relevant literature describes RY86 removal by CWs (L54-55).
For Questions 2-5, I have already answered that those are next research topic for us. Those are out of the scope of this paper.
For Question 6, I have already answer to this that "Please give us specific comments". Actually, Reviewer "No.2" gave us a comment that "The results are presented clearly, with appropriate use of tables and figures".
I have already complained to the editor about your irrelevant comments.
