Impact of Non-Metallic Organic Tanning Agents with a Double-Triazine Structure on the Microbial Community Structure in Wastewater

Round 1

Reviewer 1 Report

Authors present an interesting manuscript on the microbiological changes in wastewater containing tanning agents as contaminants. Despite their efforts, some changes must be introduced prior to publication in the Water journal:

1. English should be revised. 
2. Line 49. Literally reported is incorrect, pleasse change for "reported in literature"
3. Line 52-53 treatment is repeated twice making the sentence confusing.
4. Line 61. please rephrase using the impersonal mode.
5. Line 85. Till is informal English, please change to until.
6. Table 1. Please teger the units for COD. Do not use abbreviations that are not previously explained in the text, like COD. 
7. Section 2.1, which was the spike concentration of the different NOTAs employed?
8. Section 2.2 please list the equipment employed for the quantification of the different parameters analyzed.
9. The KB sample is unclear, is it a blank sample of wastewater without treatment? If so, how is the TOC lower than in the treated samples?
10. Section 3.1 which kind of degradation takes place? Please refer the technology and main operating parameters.
11. Line 145. Please change the term "amputation" it is incorrect. 

Author Response

• English should be revised. 
• We have used the editing services to rephrase the manuscript.
• Line 49. Literally reported is incorrect, please change for "reported in literature"
• We have revised it as line 46-48.
• Line 52-53 treatment is repeated twice making the sentence confusing.
• We have revised it as line 49-52.
• Line 61. please rephrase using the impersonal mode.
• ØWe have revised it as line 57.
• Line 85. Till is informal English, please change to until.
• We have revised it as line 79.
• Table 1. Please teger the units for COD. Do not use abbreviations that are not previously explained in the text, like COD. 
• We have revised it as Table 1.
• Section 2.1, which was the spike concentration of the different NOTAs employed?
• We havedefined the abbreviation of NOTAs in line 10, it means non-metallic organic tanning agent
• Section 2.2 please list the equipment employed for the quantification of the different parameters analyzed.
• Because the equipmentemployed for the quantification of the different parameters analyzed is very many, so we Attach reference Wei, 2002 .
• The KB sample is unclear, is it a blank sample of wastewater without treatment? If so, how is the TOC lower than in the treated samples?
• The KB sample is a blank sample of wastewater without non-metallic organic tanning agent, so its TOC is lower than in the treated samples.
• Section 3.1 which kind of degradation takes place? Please refer the technology and main operating parameters.
• The information on the criteria of selection of the non-metallic tanning agents tested was added in section 1 and marked with red.
• Line 145. Please change the term "amputation" it is incorrect. 
• We have revised it as line 412-415.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper of Xu et al. aims to evaluate the Non-metal organic tanning agents with double triazine structure as well as the correlation between the physicochemical properties of bistriazine wastewater and microbial communities.

Although the paper is of general good quality, the abstract is very poor, written in what I consider to be an unnecessary complicated manner. The abstract has to be clear and concise, with well determined structure as in the brief presentation of the work and the scope followed by the results and conclusions. Please reformulate the abstract.

The introduction lacks sufficient references and doesn't fully explain the scope of the work, the current situation and the "...insight into the ecological environment assessment of bistriazine non-metal organic synthetic tanning agents. " as well as other possible implication and ramifications. I would like to see data from authors that dealt with biofilms [1] in such industry as well as the adaptation of microorganism in toxic environments [2]. Also, citations need to be formatted in the style required by the journal and the results and discussions need to be split in two categories, Results and Discussions.

One last remark: Line 244 The antagonism of P. aeruginosa in such environments needs to be explained.

 

1. Moga, I.C., Ardelean, I., Petrescu, G., Crǎciun, N., Popa, R. The potential of biofilms from moving bed bioreactors to increase the efficiency of textile industry wastewater treatment. Industria Textila, 2018, 69(5), pp. 412–418. DOI: 10.35530/IT.069.05.1500   2. Stan-Lotter, H., Fendrihan, S. Adaption of microbial life to environmental extremes: Novel research results and application, second edition. Springer, Second Edition, 2017, pp. 1–342

Author Response

• Although the paper is of general good quality, the abstract is very poor, written in what I consider to be an unnecessary complicated manner. The abstract has to be clear and concise, with well determined structure as in the brief presentation of the work and the scope followed by the results and conclusions. Please reformulate the abstract.
• We have revised abstract as line 9-27.
• The introduction lacks sufficient references and doesn't fully explain the scope of the work, the current situation and the "...insight into the ecological environment assessment of bistriazine non-metal organic synthetic tanning agents. " as well as other possible implication and ramifications. I would like to see data from authors that dealt with biofilms [1] in such industry as well as the adaptation of microorganism in toxic environments [2]. Also, citations need to be formatted in the style required by the journal and the results and discussions need to be split in two categories, Results and Discussions.

1. Moga, I.C., Ardelean, I., Petrescu, G., Crǎciun, N., Popa, R. The potential of biofilms from moving bed bioreactors to increase the efficiency of textile industry wastewater treatment. Industria Textila, 2018, 69(5), pp. 412–418. DOI: 10.35530/IT.069.05.1500  
2. Stan-Lotter, H., Fendrihan, S. Adaption of microbial life to environmental extremes: Novel research results and application, second edition. Springer, Second Edition, 2017, pp. 1–342

• We have revised it as line 50-53.
• One last remark: Line 244 The antagonism of P. aeruginosa in such environments needs to be explained. 
• Pseudomonas aeruginosa may becan utilize the non-metal organic tanning agents as a nutrient, thus inhibiting the growth of other microorganisms.  

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper is interesting and refers to the rather difficult problem of tannery wastewater treatment. As it is known, depending on the tanning method (vegetable (tannin) or chrome), the wastewater differs in terms of quality, and thus they differ in their treatment methods. A valuable achievement is the determination of the influence of various tannins on the diversity and abundance of microorganisms in the activated sludge.

Despite the high rating of the article, I have two comments. I would ask the Authors to refer to them. I think that explaining or responding to them will facilitate the interpretation of the paper for future readers.

1. Table 2. There is such a relationship in wastewater                                 N (total) = N (organic) + N (NH4) + N (NO2) + N (NO3).                     In this table, N (NH4) is much greater than N (total). Is it a mistake or are they given in different units?
2. As mentioned in chapter 2.1. "Wastewater sample collection was done at sewage treatment plant's water aeration tanks of Shaanxi University of Science and Technology ...". The article lacks information about this wastewater treatment plant, especially about concentrations and loads of pollutants. What were the wastewater if you had to add glucose and NH 4 Cl, K2HPO4? Can tannery runoff containing such "Non-metal organic tanning agents with double triazine structure ..." be considered to have the same effect of microbial growth in other wastewater treatment plants?

Author Response

• Table 2. There is such a relationship in wastewater N (total) = N (organic) + N (NH₄) + N (NO₂) + N (NO₃).  In this table, N (NH₄) is much greater than N (total). Is it a mistake or are they given in different units?
• We've found this resultbefore, but it's the data that we've actually measured over and over again, we don't know why.
• As mentioned in chapter 2.1. "Wastewater sample collection was done at sewage treatment plant's water aeration tanks of Shaanxi University of Science and Technology ...". The article lacks information about this wastewater treatment plant, especially about concentrations and loads of pollutants. What were the wastewater if you had to add glucose and NH₄Cl, K₂HPO₄? Can tannery runoff containing such "Non-metal organic tanning agents with double triazine structure ..." be considered to have the same effect of microbial growth in other wastewater treatment plants?
• The waterof the sewage treatment plant's of Shaanxi University of Science and Technology is mainly domestic wastewater, its COD₅ is about 200 mg/L, and COD_cr is about 500 mg/L. We think if the tannery runoff containing such "Non-metal organic tanning agents with double triazine structure ..." would have the same effect of microbial growth in other similar wastewater treatment plants.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Author's have improved the writing in this new version. Still, some questions from the first revision remain unanswered (or the given answer has little relation to the question)

1. Please refer the units for COD in Table 1.
2. Section 2.1, which concentration of NOTAs was employed
3. Material and methods. Even though the analytical procedures are listed elsewhere, readers should be able to see in a glance in this paper which equipment were employed. You MUST list it in the article, regardless of the extension. If it is previously listed in another article, it shouldn't be that excesive. 
4. Section 3.1 - which kind of degradation takes place?

Please read thoroughly the questions and answer them carefully.

Author Response

• Please refer the units for COD in Table 1.
• We havereferred the units for COD in Table 1.
• Section 2.1, which concentration of NOTAs was employed
• The concentration of NOTAs was list as line 72-74, according to the ratio of 1.5%, One of the 3 NOTAs, created in a laboratory, was added to a water sample for five continuous days.
• Material and methods. Even though the analytical procedures are listed elsewhere, readers should be able to see in a glance in this paper which equipment were employed. You MUST list it in the article, regardless of the extension. If it is previously listed in another article, it shouldn't be that excesive. 
• We havelisted the equipment employed for the quantification of the different parameters analyzed as line 91-93.
• Section 3.1 - which kind of degradation takes place?
• We think biodegradation was taken place in section 3.1. Because we have determined the BOD₅/COD_Crof T2,T3,T4 before, the result was 0.38, 0.34 ,0.42, which showed that they had good biodegradation character.

Author Response File: Author Response.pdf