Changes in Organics and Nitrogen during Ozonation of Anaerobic Digester Effluent
Round 1
Reviewer 1 Report
The manuscript is focused on the effects of ozonation on the quantity and quality of organics and nitrogen. The MS is well organized and easy to understand. The results should provide basic data of the dosage and reaction time of O3 for wastewater treatment plant. Minor revised should be made as below:
- Fig. 2c is repeated in Fig. 5d.
- Make clear of legends in Fig. 2.
- Specify the difference of CODcr and CODmn in the section of 3.1.
- Please indicate potential by-products of ozonation treatment in the section of discussion.
Author Response
Response to Reviewer 1
Response: Thank you very much for your previous comments that helped us improve this manuscript.
- 2c is repeated in Fig. 5d.
Response: Fig. 2c has been changed.
- Make clear of legends in Fig. 2.
Response: Revised accordingly.
- Specify the difference between CODcr and CODmn in section 3.1.
Response: The difference between CODcr and CODmn in section 3.1 has been specified.
- Please indicate potential by-products of ozonation treatment in the section of the discussion.
Response: In discussion section regarding about by-products of ozonation treatment has been discussed.
Reviewer 2 Report
An average paper without much insight. No mention of analytical errors or statistical significance. Legends in Fig 2 to 4 sig figs! No attempt to measure the chemical changes during ozonation.
Author Response
Response: Thank you very much for reviewing this manuscript. We have read your comments carefully and tried our best to address them one by one, especially in terms of providing a more specific results evaluation. We hope that the manuscript has been improved toward the standards after this revision. Of course, the evaluation methods are not perfect, but the practice can better the chances of organics by ozone process and in the future, this could help to reduce the load of secondary treatment in the domestic wastewater treatment process.
Reviewer 3 Report
Ozone treatment to the anaerobic effluent is also an interesting topic in wastewater processing.
This study is quite well-designed and conducted systematically but there are more information to append.
1. Seen from the characteristics, the anaerobic effluent is not quite typical. TN is so high, higher than COD. Please specify the source (the raw influent of the anaerobic tank) ? Was that herb or pharmaceutical (including antibiotics) wastewater? The specific description of wastewater will get your paper a better positioning.
2. Please also specify the ORP or sulfide concentration of the wastewater. Such two items will greatly determine the efficiencies of advanced oxidation.
3. BOD/COD, instead of COD_Mn/COD_Cr, should be used to describe biodegradability. The latter only shows the differences of oxidability by chemical oxidants. Please change the way of describing COD_Mn/COD_Cr from "biodegradability". For your further studies, please conduct BOD experiment. If the source wastewater was herb or pharmaceutical wastewater, BOD/COD ratio will show a significant improvement.
4. Please pay attention to the figures. Whether all the legends are shown? Whether the significant digits of y axes are unified? Whether the types of the result points are unified(dots-only or dots with lines)?
5. What are the kinetics for the time-course of the detected items? What are the relations between such kinetic parameters and the ozone dosages?
6. Please mention the quantitative improvements in your abstract and conclusion. e.g. from xx mg/L to yy mg/L, or improved by zz%.
Author Response
Response: Thank you very much for your comments that helped us improve this manuscript.
- Seen from the characteristics, the anaerobic effluent is not quite typical. TN is so high, higher than COD. Please specify the source (the raw influent of the anaerobic tank)? Was that herb or pharmaceutical (including antibiotics) wastewater? The specific description of wastewater will get your paper a better positioning.
Response: The anaerobic digestion tank effluent (not raw influent) used in this experiment was from a sewage treatment plant. Because of the pre-treatment of digestion tank effluent, wastewater didn’t consider pharmaceutical or antibiotics detection.
- Please also specify the ORP or sulfide concentration of the wastewater. Such two items will greatly determine the efficiencies of advanced oxidation.
Response: This study doesn’t demonstrate the ORP or sulfide concentration because biogas production, as well as biogas composition, were not observed. The ORP or sulfide concentration of the wastewater was not detected.
- BOD/COD, instead of COD_Mn/COD_Cr, should be used to describe biodegradability. The latter only shows the differences in oxidability by chemical oxidants. Please change the way of describing COD_Mn/COD_Cr from "biodegradability". For your further studies, please conduct BOD experiment. If the source wastewater was herb or pharmaceutical wastewater, BOD/COD ratio will show a significant improvement.
Response: Revised accordingly.
- Please pay attention to the figures. Whether all the legends are shown? Whether the significant digits of y axes are unified? Whether the types of the result points are unified(dots-only or dots with lines)?
Response: Revised accordingly.
- What are the kinetics for the time-course of the detected items? What are the relations between such kinetic parameters and ozone dosages?
Response: In this work, difficult to determine the contribution of OH• through kinetic models. So, in this case, no kinetic study has been done for the reactions.
- Please mention the quantitative improvements in your abstract and conclusion. e.g. from xx mg/L to yy mg/L, or improved by zz%.
Response: Revised accordingly.
