Occurrence Characteristics and Ecological Risk Assessment of Organophosphorus Compounds in a Wastewater Treatment Plant and Upstream Enterprises
Round 1
Reviewer 1 Report
(1) Pls pinpoint the kind of organophosphorus into “Organophosphorus flame retardants” in title and main text;
(2) Pls provide the full name of “ECOSAR, T.E.S.T.” for their first appearance;
(3) Pls add some detail OPFRs concentration data in aquatic environments, especially in WWTPs, in introduction, some references, such as 10.1016/j.emcon.2018.06.001, 10.1016/j.chemosphere.2018.11.150 may be useful;
(4) Pls provide the QA/QC information for OPFRs analysis in section 2.1;
(5) Section 3.1: “with a relative abundance of 0.049%, 0.022%, 0.049%, and 0.01%, respectively.”, the unit for 0.049 is mg/L as provided in Table 2, pls revise them;
(6) A comparison with the literature is missing about OPFRs in aquatic environments, especially in WWTPs, in section 3.1;
(7) Tables 3-5 can be listed in supporting information, pls revise;
(8) The references list should be carefully revised.
Author Response
Dear Reviewer #1:
Thank you for your letter and the comments concerning our manuscript entitled “Occurrence characteristics and ecological risk assessment of organophosphorus in wastewater treatment plant”. (Manuscript No. water-2044394).
The comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made corrections which we hope meet with approval. Revised portion are also marking with yellow in the revised paper. The main corrections in the paper and the responds to the comments of reviewer #1 are as following:
Responds to the reviewer’s comments:
- Pls pinpoint the kind of organophosphorus into “Organophosphorus flame retardants” in title and main text;
Response: The types of organophosphorus flame retardants have been added in the first paragraph of the introduction, and references have been added, shown below.
OPFRs is a family of chemicals that became a re-emerging environmental issue. Tris-b-chloroethyl phosphate (TCEP), phosphoric acid tris (2-chloro-1-methylethyl) ester (TCPP), tris[2-chloro-1-(chloromethyl)ethyl] phosphate (TDCP) and triphenyl phosphate are used in flexible and rigid polyurethane foams, plastics, and textiles[5, 6].
- Pls provide the full name of “ECOSAR, T.E.S.T.” for their first appearance;
Response: Full name has been added in the text as follows.
ECOSAR: Ecological Structure-Activity Relationship Model; T.E.S.T: Toxicity Estimation Software Tool.
- Pls add some detail OPFRs concentration data in aquatic environments, especially in WWTPs, in introduction, some references, such as 10.1016/j.emcon.2018.06.001, 10.1016/j.chemosphere.2018.11.150 may be useful;
Response: Data on concentrations of organophosphorus flame retardants have been added to the introduction, which cites the two references mentioned above, as detailed below.
Municipal landfill leachate is an important source of contamination of OPFRs to aquatic environment. The range of total OPFRs concentrations across China was 29.0-437 and 0.652-32.4 mg/μL in raw and final leachates, respectively, and the annual emissions of OPFRs discharged were estimated to be between 170 and 7094 g [7, 8].
- Pls provide the QA/QC information for OPFRs analysis in section 2.1;
Response: The QA/QC related information of OPFRs has been added in Part 2.1, please see below for details.
All samples were analyzed for quality assurance, a 9-point calibration standard with concentrations ranging from 0.5 to 200 μg/L for the 10 targeted OPFRs was used for the calculation of concentrations in samples. The linear regression co-efficients of the calibration curves were >0.997. Internal standards were spiked into each calibration standard and samples at 20 μg/L.
- Section 3.1: “with a relative abundance of 0.049%, 0.022%, 0.049%, and 0.01%, respectively.”, the unit for 0.049 is mg/L as provided in Table 2, pls revise them;
Response: This part of the text describes the relative abundance of organophosphorus. The value in Table 2 is the concentration of organophosphorus, and the value (Table 2) has been recalculated and corrected according to the reviewer's comment.
- A comparison with the literature is missing about OPFRs in aquatic environments, especially in WWTPs, in section 3.1;
Response: According to the reviewer's comment, the concentration comparison between organophosphorus flame retardants and environmental water bodies and sewage treatment plants has been added in the second paragraph of section 3.1, and the reference has been added.
The concentration of TCEP (organophosphorus flame retardant) is 0.008 mg/L, which is significantly higher than the values in most of the WWTPs [7].
- Tables 3-5 can be listed in supporting information, pls revise;
Response: Table 3-5 has been set as supplementary table 2 and supplementary table 4-5.
- The references list should be carefully revised.
Response: The references have been carefully revised and supplemented according to the reviewer's comment.
In addition, the language and format of the paper had both been revised and marked in yellow to achieve the publication of this manuscript.
We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. We appreciate for your warm work earnestly, and hope that the correction will meet with approval.
Special thanks to you for your good comments.
Kind Regards
Shuo WANG and Guangli CAO
Reviewer 2 Report
The manuscript "Occurrence Characteristics and Ecological Risk Assessments of Organophosphorus in Upstream Enterprises and Wastewater Treatment Plant" is interesting for the scientific community but some aspects must be improved before considered for publication.
1. The lack of line numbering makes it difficult to perform a review.
2. It should be reduce the number of digits after the point, e.g. 125.215 should be 125.2 instead of 125.2. instead of 0.0125698 it should be 0.013 etc.
Please standardize this throughout the manuscript.
3. Materials and methods: sentence: “the treatment process of grid + cyclic activated sludge technology (CAST) + coagulation sedimen-tation + rotary disc filtration + UV disinfection, and the sludge treatment process of belt pressure filtration dehydration” should be redrafted by removing “ + ".
4. How can the Authors be sure that there were no other toxic substances in the tested sewage sludge?
5. Table 2 The column titles are illegible.
6. Fig 1a correct the units describing the X axis.
7. The description of the GC-MS method is missing.
Author Response
Dear Reviewer #2:
Thank you for your letter and the comments concerning our manuscript entitled “Occurrence characteristics and ecological risk assessment of organophosphorus in wastewater treatment plant”. (Manuscript No. water-2044394).
The comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made corrections which we hope meet with approval. Revised portion are also marking with yellow in the revised paper. The main corrections in the paper and the responds to the comments of reviewer #2 are as following:
Responds to the reviewer’s comments:
The manuscript "Occurrence Characteristics and Ecological Risk Assessments of Organophosphorus in Upstream Enterprises and Wastewater Treatment Plant" is interesting for the scientific community but some aspects must be improved before considered for publication.
1.The lack of line numbering makes it difficult to perform a review.
Response: The line number has been added according to the reviewer's comments.
- It should be reduce the number of digits after the point, e.g. 125.215 should be 125.2 instead of 125.2. instead of 0.0125698 it should be 0.013 etc.Please standardize this throughout the manuscript.
Response: All figures in the text and table have been corrected.
- Materials and methods: sentence: “the treatment process of grid + cyclic activated sludge technology (CAST) + coagulation sedimen-tation + rotary disc filtration + UV disinfection, and the sludge treatment process of belt pressure filtration dehydration” should be redrafted by removing “ + ".
Response: The symbols in this part have been corrected according to the reviewer's comments.
The treatment process of grid-cyclic activated sludge technology (CAST) -coagulation sedimen-tation-rotary disc filtration-UV disinfection, and the sludge treatment process of belt pressure filtration dehydration.
- How can the Authors be sure that there were no other toxic substances in the tested sewage sludge?
Response: In this study, the three methods involved in environmental risk assessment all take organophosphorus as the specific assessment object, among which ECOSAR and T.E.S.T methods need to input the analyzed component information in the calculation process. In this step, only the environmental risk of organophosphorus is evaluated after the input of organophosphorus component information. However, the calculation process of risk entropy needs to select the environmental background value of organophosphorus components for calculation. Therefore, the three methods only evaluate organophosphorus components, conversely, other toxic and harmful substances were not involved.
- Table 2 The column titles are illegible.
Response: The column headings in Table 2 have been modified to the corresponding abbreviations as shown in Table 2.
- Fig 1a correct the units describing the X axis.
Response: The text description of X axis in Figure 1a has been corrected and the value of X axis in Figure 1a is a dimensionless value.
- The description of the GC-MS method is missing.
Response: According to the reviewer's comment, relevant information about the equipment used by GC-MS has been added to the materials and methods, as well as the method description.
Moreover, peak materials in the chromatogram were qualitatively analyzed through the automatic retrieval function of the gas chromatograph–mass spectrometer (GC-MS) (Pegasus BT, LECO, America). The sample pretreatment method was solid phase extraction. The water sample was filtered with 0.45 um membrane, and then the pH value was adjusted to 4 by using hydrochloric acid or sodium hydroxide. SPE extraction column (Cleanert PEP-2) was washed with 10 mL methanol and then with 10 mL deionized water. After the extraction is finished, the ultrafints are washed to increase the filtration capacity and drain the extraction column. The extraction column was eluted twice with 4 mL methanol, and the eluent was dried with nitrogen gas. Finally, the eluent was filled to 0.5 mL with methanol containing 0.025% formic acid.
In addition, the language and format of the paper had both been revised and marked in yellow to achieve the publication of this manuscript.
We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. We appreciate for your warm work earnestly, and hope that the correction will meet with approval.
Special thanks to you for your good comments.
Kind Regards
Shuo WANG and Guangli CAO
Reviewer 3 Report
In this study the authors investigated the ecological risk of organophosphorus in upstream enterprises and wastewater treatment plant.
The subject is relevant and the work is on a good level. The manuscript fits within the scope of the journal and is well-written.
In section Materials and Methods please indicate information about the equipment (GC-MS) as name, model, brand, city, country. Also, the authors should present in more detail the method of analysis: GC-MS.
Author Response
Dear Reviewer #3:
Thank you for your letter and the comments concerning our manuscript entitled “Occurrence characteristics and ecological risk assessment of organophosphorus in wastewater treatment plant”. (Manuscript No. water-2044394).
The comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made corrections which we hope meet with approval. Revised portion are also marking with yellow in the revised paper. The main corrections in the paper and the responds to the comments of reviewer #3 are as following:
Responds to the reviewer’s comments:
In this study the authors investigated the ecological risk of organophosphorus in upstream enterprises and wastewater treatment plant.
The subject is relevant and the work is on a good level. The manuscript fits within the scope of the journal and is well-written.
In section Materials and Methods please indicate information about the equipment (GC-MS) as name, model, brand, city, country. Also, the authors should present in more detail the method of analysis: GC-MS.
Response: According to the reviewer's comment, relevant information about the equipment used by GC-MS has been added to the materials and methods, as well as the method description.
Moreover, peak materials in the chromatogram were qualitatively analyzed through the automatic retrieval function of the gas chromatograph–mass spectrometer (GC-MS) (Pegasus BT, LECO, America). The sample pretreatment method was solid phase extraction. The water sample was filtered with 0.45 um membrane, and then the pH value was adjusted to 4 by using hydrochloric acid or sodium hydroxide. SPE extraction column (Cleanert PEP-2) was washed with 10 mL methanol and then with 10 mL deionized water. After the extraction is finished, the ultrafints are washed to increase the filtration capacity and drain the extraction column. The extraction column was eluted twice with 4 mL methanol, and the eluent was dried with nitrogen gas. Finally, the eluent was filled to 0.5 mL with methanol containing 0.025% formic acid.
In addition, the language and format of the paper had both been revised and marked in yellow to achieve the publication of this manuscript.
We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. We appreciate for your warm work earnestly, and hope that the correction will meet with approval.
Special thanks to you for your good comments.
Kind Regards
Shuo WANG and Guangli CAO
Round 2
Reviewer 2 Report
Table 2 The column titles are illegible. Use a smaller font for column titles
