Sewage Markers as Determinants to Differentiate Origins of Emerging Organic Pollutants in an Urban Sri Lankan Water Drainage Network

Round 1

Reviewer 1 Report

Quyen et al. reported sewage markers that could be used as determinants to differentiate sources of selected emerging organic pollutants in an urban Sri Lankan surface water drainage systems. The report is interesting but surfers some minor flaws.

Comments:

1. Title. There many types of contaminants, it will be necessary to specify the class of contaminants considered in the report. So, I suggest that the title of the manuscript be corrected to "Sewage markers as determinants to differentiate origins of emerging organic pollutants in an urban Sri Lankan water drainage network."
2. The introduction gave little information about global trends of emerging organic pollutants in terms of occurrence, distribution, persistence, transport and fate. A brief paragraph highlighting this would be necessary. Refer to the following papers and revise the section accordingly: https://doi.org/10.1016/j.watres.2017.12.029; https://doi.org/10.1007/s11356-020-10842-9; https://doi.org/10.1016/j.gsd.2017.12.009; https://doi.org/10.1007/s42250-019-00079-6; http://dx.doi.org/10.1007/s00128-015-1639-9; https://doi.org/10.1021/acs.analchem.9b05269; https://doi.org/10.1007/978-981-32-9771-5_4;.
3. Line 18-21: Please specify which compounds gave the concentrations presented in the Abstract. Toxicity or others of contaminants may not necessarily be additive. 
4. Line 23. I think "excreta rate" should be "excretion rate". Correct this all through the manuscript.
5. Line 24: Put a full stop after "respectively". Start a new sentence with "These". Change "emphasized" to "implies".
6. Line 23-24: Correct "suitable for domestic grey and black wastewater" to "suitable to characterize domestic grey and black wastewater."
7. Line 52. correct "preserving" to "preserve".
8. Line 61. Do not start sentence with a number.
9. Line 62. The author refers to statistics reported for 2015 in a cited reference published in 2015. Were the statistics predictions?
10. Line 63: correct to "population rely".
11. Line 70: replace "proper" with "suitable".
12. Line 89-90: Correct to "Three sampling sites were considered."
13. Table 1: Explain the meaning of the abbreviation "CM."
14. Line 282: correct to "disposed off"
15. Line 314: Ref. 34 is not listed in the reference list. 
16. Line 320: Grey or grey?
17. Check the first table in the questionnaire, the spelling of "female" is wrong.
18. Was the questionnaire prepared in English language. Do local respondents use English language for primary communication? Was there translation of the questionnaire? Was there educational level requirement for the respondents to be able to fill the forms of the questionnaire?
19. Check question 6 in the questionnaire, there are some texts that are not in English. 
20. Check the table for "Personal care products" in the questionnaire, correct "disinfection" to "disinfectant".

In general, the report is interesting and provides new information that other future models may be based on to track the sources of emerging organic pollutants. To show global relevance, the introduction section needs to highlight some global trends on the topic. I recommend the manuscript for acceptance, after minor revision of the text. 

Author Response

Thank you  for your time spending on our manuscript. We have reflected every comments and make changes where needed. Please see the attachment for the point-to-point response to your comments. 

With regards,

Author Response File: Author Response.pdf

Reviewer 2 Report

The application of specific sewage markers to characterize contaminant sources is essential for managing urban sanitation and water drainage network. This manuscript presents eight target compounds were evaluated for sewage markers in various water sources within urban Galle City, Sri Lanka. It was found that the labile markers caffeine and acetaminophen were suitable for domestic grey and black wastewater markers, respectively. The conservative marker carbamazepine was useful for tracking hospital residues over long distances. These results emphasized that the city’s drainage system received both domestic greywater and human excreta, likely due to insufficient onsite sanitation systems, and hospital wastewater treatment was not working properly. The results are valuable and good references for other researchers in this field. The manuscript can be published with minor modification. The detailed comments are as follows,

1. Last paragraph in 3.1, L181, at the end of the sentence “into the city’s canals” add “(Supplemetary Information)”.
2. The last two sentences in conclusions “The complicated composition of hospital discharge suggests the need for longer-term monitoring study. Moreover, further data collection is required to determine exactly how seasonal variation affects the flow and concentration in the drainage system.” are recommended to the end of the last paragraph in 3.4. These sentences are not conclusions and should be put in discussion.

Therefore, the current manuscript can be published and the recommendation for this manuscript is minor revision.

Author Response

Thank you  for your time spending on our manuscript. We have reflected every comments and make changes where needed. Please see the attachment for the point-to-point response to your comments. 

With regards,

Author Response File: Author Response.pdf