Effects of Nitrogen in Sewage Treatment Plant Effluent on Organic Matter Target Indicator of TMDLs in Korea
Round 1
Reviewer 1 Report
This manuscript describes an effort to predict the total maximum daily load based on models which include the discharged nitrogen load in order to obtain the desired biological oxygen demand of receiving waters after five days. Adjustments were made to reduce the nitrogen oxygen demand that were attributed to ammonium so favorable BOD's could be obtained. Water quality surveys were utilized to provide some ground truth to the modeling effort. The water quality surveys did not analyze water samples for dissolved organic nitrogen directly which would have been an important check of the calculated DON that resulted from difference of total nitrogen minus DIN. In addition, the model has algae as a component but there are apparently no measurements of chlorophyll in the surveys (or the authors choose not to show the data). The absence of chlorophyll is important because ammonium is a very important and energy efficient source of nitrogen uptake for algae growth especially over a time period of five days.
In general the writing is good and the tables and figures are appropriate. The manuscript would be much stronger if more effort had been given to collection of more water quality data (e.g. light transmission and algae growth) in additional surveys throughout all months of the year.
Author Response
Thank you for your comments.
Chlorophyll-a was measured in rivers, but it was not measured in STP and WWTP effluents and thus not included in this paper. I will reflect the opinion of the reviewer when conducting related research in the future.
Thank you once again.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This manuscript examines the relationship between water quality indicators via modeling them at the sewage treatment plants and receiving waters. The application of this technique may be appropriate and potentially applicable to other areas. My suggestion is to express more clearly the focus of this paper and be consistent with it from the abstract until the conclusion as well as to meet the top tier journal's standards in terms of flow, style, and in-depth content. I suggest major revisions. Some major reasons are listed, but not limited to below:
1. A clear explanation of why the paper/problem is critical was not established in the introduction. Previous knowledge was briefly summarised but the authors should further highlight how the new information presented builds on the previous knowledge and why the analysis presented is important in the context of the study area.
2. The structure may be adjusted. Some descriptions associated with the methods in the Results and discussion section should be moved to the Materials and methods section.
3. The link given for at least one reference did not work so they should all be checked.
4. The use of acronyms should be checked and corrected throughout the whole text. When using an acronym, the words should be spelled out at the place where they come first. In addition, Tables and figures should be stand alone, without any text explanation.
5. The quality of figures is extremely poor. Most of the figures should be improved.
6. The manuscript still has many grammatical and editorial errors.
7. Conclusions to the work should be reframed and authors should rather state their findings in relation to the objectives of the work.
Author Response
Thank you for your comments and suggestions, which have helped improve the quality of the text.
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The writing is good and the tables and figures are appropriate.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
