Investigation of the Mechanism for Removal of Typical Pathogenic Bacteria from Three-Compartment Septic Tanks under Low Temperature Conditions

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript entitled "Investigation of the mechanism for removal of typical pathogenic bacteria from three-compartment septic tanks under low temperature conditions" describes the treatment method of the rural three-compartment septic tank to reduce the pathogenic bacteria of Enterococcus faecalis, Escherichia coli, Staphylococcus aureus, and Salmonella enteritidis. It requires minor revisions as follows:

1.  The introduction section needed more details to present the importance of the use of the three-compartment septic tank.

2.  Moreover, the introduction section needed some enhancement by focusing on the previous studies in the same area.

3.  Also, please explain the ability and mechanism of different treatment methods used in the literature to enhance the the three-compartment septic tank.

4.  What is the new novelty of the present study in comparison with previous work, it must be modified on pages 3 and 4 to be clear for readers.

5.  On page 3, a section of (2. Material and methods) line 125, please show the reasons behind the selection of the retention to be for G₁ was set at 20 days, for G₂ 10 days, and for G₃ 30 days.

6.  More discussions are needed for Figures 4 and 5, and also for Table 2 in the results and discussion sections.

 

7.  A comparison of the present work results with the results of other work is needed.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In my opinion the manuscript is carefully and well written.  It can be seen  that the authors have put a lot of work into this work.

However, I have a few comments:

1) “To simulate wastewater input, it was assumed that each person would contribute 5 urinations and 1 defecation per day. Accordingly, six daily wastewater inputs were introduced, with water being added every 4 hours at a rate of 48 mL each time. The retention time for G1 was set at 20 days, for G2 10 days, and for G3 30 days. On the 60th day, G3 reached its full capacity, and the wastewater was extracted through the sludge outlet.” Maybe the author would consider moving this information to the section “2.2. Inflow and inoculum”

2) Page 4, line 154: “The physicochemical parameters, namely pH, COD, and NH3-N, were assessed by the established methodologies [24]”. If it's not a problem I would just list the methods in parentheses.

3) In “2.4. RNA extraction and real-time PCR analysis”

Authors wrote: “Utilizing the aforementioned collected fecal water (at identical time points as the physicochemical indicators), RNA extraction was carried out”. This term (fecal water) first time appears in Material and methods  - please mention in earlier parts of Material and methods what constitutes fecal water.

 

4) There is a table S1 in Supplementary Materials but there is no reference to it in the text.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Editor and Authors:

Investigation of the mechanism for removal of typical pathogenic bacteria from three-compartment septic tanks under low temperature conditions

Overall, this work presents a satisfactory novelty with interesting results, and it deserves to be considered for publication. The work is well written and it has many useful data/results and discussion. In addition, this work presents a technology that has large application worldwide therefore this work has the potential to attract huge attention and be cited. However, the authors are requested to respond to the following comments and suggestions to improve the quality of the manuscript further to publish in Processes.

Some other issues that need to be addressed are:

(1)        The novelty of the work should be more explicated; in addition, the contribution of the topic paper should be better written this paper in relation to the empirical literature.

(2)        The authors should mention the concept of this work with the progress against the most recent state-of-the-art similar studies.

(3)        The authors stressed that the mechanism for the removal of typical pathogenic bacteria was investigated but such a mechanism is not clear in the paper. Perhaps a figure showing the mechanism should be incorporated in the paper.

(4)        Lines 376-379: “The relative abundance of Christensenellaceae_R-7_group decreases during fermentation, from 22.8% to 2.8% at 14 days, and further declines to 0.2% in the effluent. The reduction in Christensenellaceae_R-7_group may be due to the scarcity of sugar-based organic compounds within three-compartment septic tanks.” Why sugar-based organi affects only this class of bacteria and not the others

(5)        Please, provide a set of limitations if any.

 (6)        Please, provide a set of recommendations to be performed in future studies to obtain more reliable and accurate results to use for developing the technology further

Author Response

Please see the attachment.

Author Response File: Author Response.pdf