The Summary of Nitritation Process in Mainstream Wastewater Treatment
, Ze Zhang 1, Chuanfu Wu 1,2, Ming Gao 1,2,* and Feng Liu 3Round 1
Reviewer 1 Report
In this manuscript, recent advances in nitrite production processes and the main species and characteristics involved in the biological nitritation process were reviewed. And also, this review proposes a two-stage process that combines photocatalytic oxidation and inorganic salt oxidation. The article has a positive effect on the summary of progress and future development of the PN/A process. However, moderate revisions are needed in the current edition. It was recommended for acceptance after appropriate revision.
General Suggestion:
1. It is recommended that the structure of the article be optimized as some headline errors may confuse the reader; it is also recommended that a sentence be added after the introduction to biological nitritation, for example by dividing this section into two parts, A and B, for a more detailed introduction, which would make the paper clearer.
Specific suggestion:
1. If it can be modified, the height of the superscript can be adjusted so that the chemical formula can be made more beautiful, such as NH4+.
2. Page 3, The headline, “2.2 Biological nitritation” should be modified to “2 Biological nitritation”.
3. Page 6, Table 2, The table is not fully visible and can be illustrated as supplementary material if it cannot be shown on a horizontal page.
4. Page 8, Equations (9) and (10), The two formulas could be spaced further apart to avoid compromising aesthetics by being too compact.
5. Page 10, section 2.2, It is proposed to preface the introduction of the following 6 aspects with the sentence "This paper will present the factors influencing the assisted nitrification process through these 6 aspects".
6. Page 12, section 3, This section does not provide a supporting explanation for the first paragraph of Part 3 and it is suggested that “This section may be divided by subheadings. It should provide a concise and precise description of the experimental results, their interpretation, as well as the experimental conclusions that can be drawn.” be deleted.
7. Some relevant studies can be cited, Science of the Total Environment, 2023, 857, 159462; Bioresource Technology, 2022, 361, 127750; Journal of Environmental Sciences, 2023, 125, 160-170; Journal of Environmental Management, 2021, 296, 113271; Chemosphere, 2021, 278, 130436.
8. Page 14, section 3, “10.5pH” should be modified to “pH 10.5”.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The current methods of nitrite production are outlined in this paper, along with the main microbial species and characteristics involved in the biological nitrition process, as well as the problems and N2O emissions in the various nitrite production processes. a promising method is presented in this paper
Please add a list of abbreviations
The subtitles must be written in full without abbreviations in clause 2.1.3
7- conclusions without (s)
Standardization of writing Figure or Fig at all paper
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
In the review paper “The Summary of Nitritation Process in Mainstream Wastewater Treatment”, the authors focus on the nitrite production issues in partial nitritation/anammox processes. Both the biological and physicochemical photocatalytic methods for ammonia oxidation are reviewed. The influence of different parameters on nitritation performance is well summarized. The risk of N2O generations is also included. The topic is interesting and relevant to the scope of the journal. The content is informative and well organized, and the length and structure are appropriate. Generally, the manuscript can be accepted after being minor revised.
The detailed comments are as follows:
1. The subtitle number is not correctly set. There are two “2.2” chapters. Please check.
2. The position of Chapter “Biological nitritation” is not logically appropriate. Also, please be very careful to propose the exact percentage of wastewater distribution simply based on the theoretical nitrogen balance calculation. The theoretical value should be supported by a more rigorous model, e.g., the match of wastewater flow rate and microbial metabolic/growth rate should be considered. Besides, a practical number should also be cited for comparisons.
3. In Chapter 2.1.3, it would be better if the abbreviations in the subtitles could be spelled out, e.g., SRT, FNA, FA.
4. The Chapter “N2O emission” should be placed ahead of “Existing problems”.
5. The Chapter “Prospective process” should be deleted or merged into Chapter “Existing problems”.
6. Please check and unify the British/American English spelling, e.g., “summarise” and “summarize”.
7. The conclusion should be more concentrated on the key content of this manuscript. Besides, the novelty should also be emphasized.
Author Response
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Author Response File: Author Response.pdf
