Trihalomethanes in Water Supply System and Water Distribution Networks

Round 1

Reviewer 1 Report

Study of Trihalomethanes in Water Supply System and Water Distribution Networks

 

The authors informs us of the trihalomethane that are found in the water supply system and the water distribution networks in Chiang Mai Province in Thailand. The results show relationships between the formation of trihalomethanes and pH, alkalinity and DOC (Dissolved Organic Carbon).

 

However, some corrections are needed is this paper is to be accepted for publication.

 

ABSTRACT:

The abstract does not have structure, 1) Background: Place the question addressed in a broad context and highlight the purpose of the study; 2) Methods: Describe briefly the main methods or treatments applied. Include any relevant preregistration numbers, and species and strains of any animals used. 3) Results: Summarize the article's main findings; and 4) Conclusion: Indicate the main conclusions or interpretations which is mentioned in the IJERPH website (https://www.mdpi.com/journal/ijerph/instructions#manuscript). There is no methodology used, Background and the results also include some methodology. The structure above should be followed.

 

Introduction.

 

Line 39; The sentence that starts with “At present, the population is increased” needs a reference, specifically where the authors mentioned that At present, the population is increased.

Line 47; The sentence that say “During the disinfection process, the most common disinfectants are chlorine,” maybe the word “used” should be inserted between disinfected and are. This is just a suggestion. The sentence still makes sense the way it is, however, it would read well if used is inserted.

Line 61; “In addition, iodinated DBPs, such as iodinated THMs were found”. The question I have here is where were all those chemicals found? Maybe a reference will assist here or putting the sentese into context.

Line 98: “During each collection, five liters of water “was” sampled”. Insert was.

Results:

Line 130: The measurements were done on samples taken from two seasons: wet and dry season. This sentence is part of the methodology.

 

Line 140: It should be mentioned under the chemical analysis in the methodology that Calcium carbonate was measured representing alkalinity.

 

Line 159: Unless if Results are combined with discussion, then we can have references in the results and discussion. However, in this manuscript they are not, so there should be no references in the results section.

 

Line 160-167: This section should be in the discussion section, justifying what has been identified in the current study.

Discussion.

Line 180: A short sentence for introducing the results will help in this case. Inform us of the effect of trehalomethane formation at different Ph (e.g). This will be based on the results obtained. The struck out sentence is part of the results. It should be in the results section.

 

A paper titled: pH effect on the formation of THM and HAA disinfection byproducts and potential control strategies for food processing” might help.

 

Authors are Yen-Con Hung1, Brian W. Waters2, Veerachandra K. Yemmireddy1, Ching-Hua Huang3

Conclusions.

Line 248-268. This section should be short and conclude on the results obtained. "With the incidence of waterborne diseases on the rise, it becomes increasingly important for consumers to adopt measures to ensure water safety.     Based on the information in this article, pH plays an important role in the determination of the type and amount of DBPs formed, with lower, more acidic, pHs resulting in the formation of less chloroform. Just an example. The authors can also interpret the obtained results.

 

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

1. The novelty of the paper is not highlighted.
2. Most of the references are published before 2013. The new and relevant information about THMs formation in tap water should be integrated into the introduction, discussion.
3. The authors just listed the water quality parameters and THMs levels, but without any deep discussion. Such as is there any relationship between water quality parameters and the THMs formation? which water quality is the best indicator for THMs precursor? UVA or DOC?
4. The authors should check the grammar, logic throughout the text.
5. The water supply system is essential to the people living in Chiang Mai Province, Thailand.
6. the water supply system is not only essential to the people living in Chiang Mai Province, but also for the people all of the world.
7. Line 53, [9-10], more recent and relevant references (such as Journal of Hydrology 591 (2020) 125574) is necessary here.
8. Line 63-65, the factors of bromide, iodine level were also important for DBPs (including THMs) formation. please add relevant reference (e.g. Science of the Total Environment, 590 (2017) 720-728) here.
9. Line 193, From the raised DOC results for both seasons.
10. This sentence is not complete.
11. 3-5, 7, wet season including which months? How about wet season? Please clarify “wet season” and “dry season” in the figure.
12. Line 216, the SUVA was higher than in the dry season and the organic matter in raw water was a double bond type.
13. High SUVA means the organic matter has higher ratio of the double bond, but not means all of the organic matter are double bond type.
14. Line 217-219, These substances must be removed because they did not create carcinogens as the water underwent chlorination with disinfectants in the water supply system.
15. The logic of this sentence is right?
16. From Figure 2, we can see “Chlorination” was used in this water supply. yet in Line 228, the authors said “Substantial amounts of THMs were formed after chlorine dioxide disinfection.”, and in line 240. which one is right??
17. Line 231-232, unit is necessary after these data.
18. Line 235, “the SUVA value of raw water is greater than 2 mg/L, the organic compounds must belong to the double bond group.”
19. The word “must” is not suitable. “Organic compounds dominated by the double bond group” is more scientific.
20. Line 236-237, These substances are precursors to the reaction with chlorine disinfectants in disinfection processes.
21. This sentence is too lengthy and the structure is not reasonable.
22. “These substances are precursors for DBPs (including THMs), which are produced during reaction with chlorine during disinfection process.” may be better.
23. Line 246-266, the TTHM concentration during the wet season was in the range of 31.99-71.72%, while the value was 50.78-75.80% for the dry season. The value is lower during the dry season than the wet season.
24. The statement was inconsistent within these two sentences.
25. The value is lower during the dry season than the wet season possibly due to the higher temperature, causing the TTHMs to evaporate along the water supply line.
26. Usually, the water supply pipeline is closed not open to the air. Therefore, it is difficult for THMs for evaporate. I think, the seasonal difference of water quality may be the key reason that caused seasonal difference in THMs formation. About this point, the authors should integrate the following relevant references into the discussion.
27. Chemosphere, 286 (2022) 131586; Ecotoxicology and Environmental Safety, 171 (2019) 813-822, where there is detailed discussion about the seasonal different of THMs in tap water and the related water quality parameters.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors have made an extensive revision on the manuscript, and have addressed all of my concerns. Since then, I suggest to accept publication of this manuscript in current form.