Factors Affecting the Morphology of Granular Sludge in Phosphorus-Accumulating Organism (PAO) and Denitrifying PAO (DPAO) Sequencing Batch Reactors

Round 1

Reviewer 1 Report

The topic is good but it needs a lot of correction before further process:

1. Synthetic wastewater composition is not clear, neither any reference is given for that.

2. Adsorbent in reactor is not explained, neither characterized properly.

3. What is used to check quality of treated water? Explain that method along with instrumentation applied.

4. Give the hazardous effects of sludge used in intro section.

5. Add bar graphs for optimization of operational parameters.

6. Give characteristics of used sludge after removing from reactor and before dumping it. Can it be recycled?/ Check the possibility of recycling it by desorption.

7. Compare process efficiency and also give approximate cost estimate for adopting this method on pilot scale water treatment.

8. Compare your result optimized conditions with recent literature and add latest references to explore the novelty of your work.

Overall poorly presented a good topic, which can be improved further after these corrections.

The topic is good but it needs a lot of correction before further process:

1. Synthetic wastewater composition is not clear, neither any reference is given for that.

2. Adsorbent in reactor is not explained, neither characterized properly.

3. What is used to check quality of treated water? Explain that method along with instrumentation applied.

4. Give the hazardous effects of sludge used in intro section.

5. Add bar graphs for optimization of operational parameters.

6. Give characteristics of used sludge after removing from reactor and before dumping it. Can it be recycled?/ Check the possibility of recycling it by desorption.

7. Compare process efficiency and also give approximate cost estimate for adopting this method on pilot scale water treatment.

8. Compare your result optimized conditions with recent literature and add latest references to explore the novelty of your work.

Overall poorly presented a good topic, which can be improved further after these corrections.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

In the current manuscript, the authors investigated the factors affecting the morphology of sludge granules from the alternating conditions of DPAO SBR and PAO SBR. The obtained results are supported by the relevant characterizations. However, major revisions are required before acceptance;

1.   The scientific language of the manuscript requires major improvement.

2.   The authors must mention why no core was observed in An-Ox granules.

3.   What type of chemical reactions result in the formation of core precipitation?

4.   Why PAO granule did not contain a core precipitate?

5.   The authors should mention the planes of XRD.

6.   Comparison of the obtained relationship between granule size and various operating should be done with recent literature

7.   Why diameter of DPAO granules were larger than PAO granules?

8.   How alkaline conditions can aid in developing HAP core in DPAO granule

9.   The conclusion section should be improved.

10.  The authors should cite recent work, especially from 2020-2023.

Must be improved

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Manuscript can be accepted in the present form. 

Author Response

We appreciate the reviewer’s comments with regards to our manuscript. 

Reviewer 4 Report

The paper is interesting and should definitely be published in Water magazine. The research was carried out professionally and the results were compared with a large number of other references. Analysis of parameters that influence the growth of granules and their structure may contribute to corrections in the operation of sewage treatment plants, especially SBR reactors on a technical scale. The test results may lead not only to improved effectiveness, but also to an increase in the sludge deposition rate.

The article is well written and does not require additional actions after previous correction. Only Fig. 5 is difficult to read and, even at the expense of the size of the article, it should be printed larger. The only doubt was raised about the conclusions regarding hydroxyapatite. Has struvite been detected in addition to hydroxyapatite? They usually appear next to each other. Then it would be necessary to measure the concentration of not only calcium, but also magnesium.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Authors have rectified manuscript, now ok for further process.

Author Response

Thank you for your decision.

Reviewer 2 Report

The authors have addressed all comments and the manuscript can be accepted for publication

Author Response

Thank you for your decision.