Study on the Migration Law of Dissolved Organic Matter in Mine Water Treatment Station

Round 1

Reviewer 1 Report

The paper focuses on the investigation of the systematic characterization of DOM in mine water treatment effluent to ascertain the efficiency of the treatment process. The study is well designed, and the findings are relevant. The authors should consider my comments below to improve the paper.

 

The title does not reflect the work done and should be rephrased.

The authors must refrain from using the personal pronoun; e.g. line 103: “Here, we used EEM combined…”.

The authors must provide the coordinates of the sampling sites for reference.

Fig 5, the authors must write all the axes titles in English.

Page 10, line 280, the authors must properly write the equations and number them.

Fig 6, since the authors carried out the experiments in triplicate, they must provide error bars for each bar graph.

The authors samples at 15 areas, but only reported for one area; why was it important to sample at so many areas if the results are not reported?

The authors must proofread the text to address typo and grammatical mistakes.

Author Response

Dear Editor and Expert，

Thank you for your careful review. I have revised the original text in detail according to experts' opinions. And answered the experts' questions, as follows:

Question 1. The title does not reflect the work done and should be rephrased.

Answer: This work has been completed, and the title is modified as follows: Study on the migration law of dissolved organic matter in mine water treatment station

Question 2. The authors must refrain from using the personal pronoun; e.g. line 103: “Here, we used EEM combined…”.

Answer: The personal pronouns in the text have been modified.

Question 3. The authors must provide the coordinates of the sampling sites for reference.

Answer: The coordinates of sampling points have been marked in the original text,The Cao jia tan(109°48′02.61″E,38°32′27.12″N), Ma huang liang(109°56′47″E,38°25′31″N), Yu shu wan(109°52′36″E,38°28′42″N), Xiao ji han(109°25′72″″E,38°22′17.99″N), Yu bu jie(109°42′00″E,38°24′50″N), Shi la wu su(109°35′00″E,38°59′00″N), Xue miao tan(109°42′00″E,38°25′50″N), Xiao bao dang(109°45′27″E,38°41′50″N), Ba yan gao le(109°19′00″E,38°42′45″N), Shuang shan(109°55′01″E,38°26′25″N), Long de(110°03′05″E,38°43′58″N), Jin jie(110°06′00″E,38°46′30″N), Jin ji tan(109°42′32″E,38°28′15″N), Hang lai wan(109°46′49″E,38°24′52″N) coal mine water treatment plants were selected for this study.

Question 4. Fig 5, the authors must write all the axes titles in English.

Answer: Figure 5 has been modified, see Annex - Figure 5 of the revised version for details.

Question 5. Page 10, line 280, the authors must properly write the equations and number them.

Answer: The chemical reaction equation of nitrate nitrification and denitrification in line 280 on page 10 has been checked and modified.

Question 6. Fig 6, since the authors carried out the experiments in triplicate, they must provide error bars for each bar graph.

Answer: Error bars have been added according to the source data in Figure 6, see Annex - Figure 6 of the revised version for details.

Question 7. The authors samples at 15 areas, but only reported for one area; why was it important to sample at so many areas if the results are not reported?

Answer: This study is mainly divided into three steps. First, take samples from the outlets of mine water treatment stations of 15 large modern mines in Yushen and Shenfu mining areas in the north Shaanxi coal base in northwest China, and carry out EEMs analysis and PARAFAC calculation. The purpose is to understand the current situation of DOM pollution of mine water in the region and the possible environmental risks after discharge; Secondly, specific analysis is carried out for Caojiatan Coal Mine, which has the largest output in the area. The water inlet and outlet of its mine water treatment station are analyzed respectively to investigate the removal efficiency of organic and inorganic pollutants under the treatment process; Finally, it was found that protein tyrosine like was not degraded in the whole treatment process. It was analyzed that the current treatment process could not realize chain breaking due to the high bond energy of macromolecular polycyclic aromatic hydrocarbons. Based on this, a combined process of "ozone air flotation" was proposed. Therefore, it is equally important to take samples from 15 mines, which is of far-reaching significance for understanding the current situation of DOM pollution in the region.

Question 8. The authors must proofread the text to address typo and grammatical mistakes.

Answer: Finished proofreading.

I have no conflicts of interest to disclose.

Please address all correspondence concerning this manuscript to me at [email protected].

Thank you for your consideration of this manuscript.

Sincerely,

Xiyu Zhang

Author Response File: Author Response.docx

Reviewer 2 Report

Dear author,

I have some comments to your interesting paper.

- Please, check your English, e.g. in the introduction you switch the tense from past perfect, simple past to present. In some cases it is not clear whether active or passive is used.

- Please introduce all abbreviations after first use and not after the second or even later, e.g. COD within the abstract. You explain it later. 

- In Fif. 1 black on blue is hard to read (groundwater). White would be better.

- Where exactly did you collected your samples? Can you show the point in Fig. 2 or is this irrelevant according to Fig. 3? 

- Your samples have been stored in glass bottles. Were they sealed to avoid oxygen ingress? I assume that oxygen leads to side reactions as you mention by the oxidation of ammonium.

- What are the zone I-V in Fig. 4? It is not mentioned in the text (lines 214-221).

- Please transform the Chinese signs in English (Fig. 5).

- Cu can form complex compounds with your amino acids. Does this have any impact?

- Cu, F, SO4, Cl are inorganic pollutants. They are substantially descibed in the results section but in the abstract and the introduction.

- Potassium permanganate for measuring COP is not according to ISO 1060?!

- What do you mean reduction by 300% via UV?

Regards

Reviewer

Author Response

Dear Editor and Expert，

Thank you for your careful review. I have revised the original text in detail according to experts' opinions. And answered the experts' questions,as follows:

Question 1. Please, check your English, e.g. in the introduction you switch the tense from past perfect, simple past to present. In some cases it is not clear whether active or passive is used.

Answer: The English tenses and voices of the full text have been checked and revised (see the revised version for details).

Question 2. Please introduce all abbreviations after first use and not after the second or even later, e.g. COD within the abstract. You explain it later.

Answer: The abbreviations in the full text have been checked and the full name remarks have been added at the first occurrence.

Question 3. In Fif. 1 black on blue is hard to read (groundwater). White would be better.

Answer: Figure 1 has been modified as required by experts.

Question 4. Where exactly did you collected your samples? Can you show the point in Fig. 2 or is this irrelevant according to Fig. 3?

Answer: The samples were collected from the inlets and outlets of the mine water treatment stations of 15 large-scale mechanized mines in Yushen and Shenfu mining areas of the North Shaanxi Coal Base in northwest China. The locations of these 15 mines have been marked in Figure 3. Figure 2 refers to the commonly used "coagulation filtration disinfection" treatment process for these mine water.

Question 5. Your samples have been stored in glass bottles. Were they sealed to avoid oxygen ingress? I assume that oxygen leads to side reactions as you mention by the oxidation of ammonium.

Answer: As experts said, oxygen leads to side reactions as you mention by the oxidation of ammonia. Therefore, the glass sampling bottle used in this study is equipped with a sealing plug to prevent oxygen from entering. At the same time, after sampling, it will be quickly sent to the testing agency for sample analysis, so as to avoid side reactions caused by sample oxidation as much as possible.

Question 6. What are the zone I-V in Fig. 4? It is not mentioned in the text (lines 214-221).

Answer: To better understand the fluorescence characteristics of mine water samples of the experiment, the whole spectral range was divided into five regions The three-dimensional fluorescence spectrum is divided into five regions, representing tyrosine like (region I), tryptophan like (region II), fulvic acids (region III), dissolved microbial metabolites (region IV) and humic acids (region V) organics respectively.

Chen, W., Westerhoff, P., Leenheer, J.A., Booksh, K., 2003. Fluorescence excitation emission matrix regional integration to quantify spectra for dissolved organic matter. Environ. Sci. Technol. 37 (24), 5701e5710.

Zhu, B., Ryan, D.K., 2016. Characterizing the interaction between uranyl ion and fulvic acid using regional integration analysis (RIA) and fluorescence quenching.J. Environ. Radioact. 153, 97e103.

Question 7. Please transform the Chinese signs in English (Fig. 5).  

Answer: The modification has been completed (see the revised draft for details).       

 Question 8. Cu can form complex compounds with your amino acids. Does this have any impact?

Answer: Owning to the presence of functional groups, such as hydroxylic, carboxylic and alcohol hydroxylic groups, dissolved organic matter (DOM) can interact with metal ions in a number of ways including complexation, ion exchange and reduction, which indicates that DOM plays an important role in heavy metals speciation and migration. For instance, humic acids can react with iron and manganese ions, causing discoloration and quality deterioration of water. inding properties between heavy metals and DOM from different sources had been widely reported in many samples, including surface water, soil, sediment, landfill eachate, and mine water. However, during the migration of mine water,previous studies did not fully consider the potential impacts of the geochemical process of mine water and rock media on the binding characteristics of DOM and heavy metals. In this study, the concentration of Cu2+in mine water is always lower than 0.01 mg/L, so the formation of complex with DOM can be ignored。

Question 9. Cu, F, SO4, Cl are inorganic pollutants. They are substantially descibed in the results section but in the abstract and the introduction.

Answer: According to experts' suggestions, the removal efficiency of this treatment process for Cu2+, F-, SO42- and Cl- has been increased in the conclusion.

Question 10. Potassium permanganate for measuring COP is not according to ISO 1060?!

Answer: Sorry, because of my own reasons, I can't understand what indicators COP refers to, so I may not be able to answer this question.

Question 11. What do you mean reduction by 300% via UV?

Answer: The concentrations of UV254 increased significantly after treatment because the system had no oxidation unit. In water, this mostly represented aromatic hydrocarbons and heterocyclic organic compounds with a benzene ring structure. In the process of treatment, the macromolecular organic compounds with ring structure can not really break the chain, so the UV254 value changes.

 

I have no conflicts of interest to disclose.

Please address all correspondence concerning this manuscript to me at [email protected].

Thank you for your consideration of this manuscript.

Sincerely,

Xiyu Zhang

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Satisfied with the changes.