Treatment of High-Ammonia-Nitrogen Wastewater with Immobilized Ammonia-Oxidizing Bacteria Alcaligenes sp. TD-94 and Paracoccus sp. TD-10

Round 1

Reviewer 1 Report

1.      The work lacks line numbers, so it is difficult to indicate the commented fragment of the text.

2.      In the last paragraph in the Introduction chapter, the aim of the work is given, but it is not very precise. The purpose of the work should be clearly and precisely defined - it should be improved.

3.      In graphs on vertical axes, units should be given in product form (as in the text)

4.      In Figure 6, the values are difficult to read. I believe that a scale of values on two vertical axes should be used depending on the value range of inflow and outflow.

 

The paper, after taking into account the corrections contained in points 1-4, may be published

Author Response

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Reviewer 2 Report

The present manuscript investigates the possible treatment of high ammonium nitrogen wastewater using the nature of Alcaligenes and Paracoccus species. The research is interesting.  However the introduction does not provide any information on these microorganisms and no at least brief description of other similar or identical treatment schemes. Please clearly state the aim of the study. Alkaline activated carbon was the effective approach but the authors do not justify this finding, which actually lies upon the nature of the bacterial species. Please provide in a plain table the physicochemical characteristics of the ammonium nitrogen wastewater. Section 3.3, authors need to justify and enhance the discussion on the statement  ‘’immobilized microbial cells using modified activated carbon were more effective...’’. Please include the % removal rates in the abstract and in the conclusions.

Author Response

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Reviewer 3 Report

In the manuscript, Alcaligenes sp. TD-94 and Paracoccus sp. TD-10 were immobilized on granular activated carbon (GAC) to increase the efficiency of ammonia nitrogen removal from wastewater; modification of GAC was tested to improve removal.

There are a variety of studies and technical plants where ammonia nitrogen is efficiently removed from wastewater by using mixed microbial cultures such as activated sludge, biofilm or aerobic granular sludge, using processes such as nitrification/denitrification, Anammox, depending on the C/N. Therefore, the rationale for using pure microbial cultures for the treatment of synthetic wastewater should be clearly stated.

What was the reason for immobilizing Alcaligenes sp. TD-94 and Paracoccus sp. TD-10? Alcaligenes sp. and Paracoccus sp. are known to be potential denitrifiers capable of heterotrophic nitrification; in the text they are referred to as ammonia-oxidizing bacteria without comment. Section 3.4.2. states: “denitrification performance of (…) ammonia-oxidizing compound bacteria”. This point is unclear.

It is completely unclear what is meant by this: “ammonia-oxidizing COMPOSITE bacteria”, “a COMPOUND of ammonia-oxidizing bacteria”, “ammonia-oxidizing COMPOUND bacteria”, “bacterial AGENT group”.

How can the high accumulation of nitrites in GAC-TD-94+TD-10 and NaOH-GAC-TD-94+TD-10 (Fig. 3b) be explained? In general, nitrogen removal should be discussed in more detail.

The statement “The contributions of adsorption and biodegradation to ammonia nitrogen were 9.73% and 90.27%, respectively, should be evidenced by presenting the results; how were these contributions determined?  

Fig. 5: The x axis should be titled “Reaction time” instead of “Fermentation time”.

The Authors calculated ammonia nitrogen removal rates and efficiency. Removal rates should be expressed in, for example, mg/(L·d), while the removal efficiency in %. The Authors should correct this nomenclature throughout the text.

Author Response

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Round 2

Reviewer 2 Report

The authors have addressed most of the concerns regarding the manuscript, which could be accepted for publication.

Reviewer 3 Report

All my comments have been addressed satisfactorily.