Light Enables Partial Nitrification and Algal-Bacterial Consortium in Rotating Biological Contactors: Performance and Microbial Community
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe research question of reducing energy consumption by inhibiting NOB using light does not appear correct. When free ammonia concentration is high, NOB is inhibited regardless of light. For energy saving when nitrification is not required, a short-term sludge age (solids retention time) of 1~2 days is typically adopted, like the South San Francisco Wastewater Treatment Plant, where ammonia is not required in the effluent permit. Thus, the authors should explain the reasons for the research before any further evaluation is made. Here are the initial reviews.
Lines 10-11:
Traditional control measures for partial nitrification, such as intermittent aeration, low DO, and FA inhibition, suffer from high energy consumption and complicated operation and management. – This statement needs to be justified. Intermittent aeration, low DO, and FA inhibition are not traditional control measures. A short sludge age operation can minimize nitrification if ammonia is not regulated. This will significantly reduce energy. Wastewater containing high levels of free ammonia used in the study can inhibit NOB.
Line 14: Spell out NOB
Line 16: free nitric acid (FA) -> … (FNA)
Line 18: … rapidly, ARE and … -> … rapidely and ARE and NAR were 64.21% and 69.45%, respectively. -> So what? Needs explanation.
Line 20: Spell out EPS
Line 23: … decreased by 1.74% and 5.15%, respectively. -> Is it significant statistically? So what?
Lines 43-45: Why do you inhibit NOB when partial nitrification occurs due to NOB inhibition by free ammonia?
Comments on the Quality of English LanguageNeeds some editing.
Author Response
Thank you for taking the time to review our manuscript titled Light Enables Partial Nitrification and Algal-Bacterial Consortia in Rotating Biological Contactors: Performance and Microbial Community. We appreciate your valuable feedback and suggestions. We have carefully considered your comments and made the necessary revisions to address the concerns raised. In order to make it easier for you to check the revisions, we have marked the changes in the manuscript in red for content and in blue for grammar. Responses to your comments are attached。
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsCan You explain economic effect of the proposed method with regard to the use of LED lighting.
In Line 169 and 170 please describe in detail used methods because there is a number of derivate methods.
In paragraph 2.3.4. "Oxygen Uptake Rate Analytical Methods" You did not specify which instrument was used.
In paragraph 2.3.5. "Microbilogical Analytical Methods" is missing how did You isolated nucleic acids and how did You prepared libraries. Also which sequence are primers and what was the sequence depth?
Author Response
Thank you for taking the time to review our manuscript titled Light Enables Partial Nitrification and Algal-Bacterial Consortia in Rotating Biological Contactors: Performance and Microbial Community. We appreciate your valuable feedback and suggestions. We have carefully considered your comments and made the necessary revisions to address the concerns raised. In order to make it easier for you to check the revisions, we have marked the changes in the manuscript in red for content and in blue for grammar. Responses to your comments are attached。
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe current Essay is subjected to some improvement before being accepted for publication:
1. There are many factors affecting efficiency of RBC such as light, O2 supply etc. Can author explain which operating parameter has more effect on RBC performance?
2. Section 2.1 Lamp detail is missing such as lamp power, intensity (mW/cm2) etc.
3. A separate abbreviation list should be provided at the end, there is repetition in abbreviation in the manuscript text such as extracellular polymeric substance (EPS) line 352 and line 372, also check others.
4. All Figures font and styles should be consistent.
5. The schematic diagram of nitrification using RBC in presence of light should be provided for better understanding.
Author Response
Thank you for taking the time to review our manuscript titled Light Enables Partial Nitrification and Algal-Bacterial Consortia in Rotating Biological Contactors: Performance and Microbial Community. We appreciate your valuable feedback and suggestions. We have carefully considered your comments and made the necessary revisions to address the concerns raised. In order to make it easier for you to check the revisions, we have marked the changes in the manuscript in red for content and in blue for grammar. Responses to your comments are attached。
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsCurrently, partial nitrification is mostly studied in sequential batch reactors, and some of the methods to realize partial nitrification in continuous flow reactors have problems such as complicated operation and management as well as easy to be destabilized. This study introduces a novel system utilizing light to establish an algal-bacterial consortium within a partial nitrification framework, where oxygen is supplied by algae and a novel rotating biological contactor (RBC). The results are comprehensive and interesting. The novelty of this work is high.
(1)If RBCs are integrated with an algal-bacterial consortia, the biofilm can be fully utilized when exposed to air. Bacteria and algae form a biofilm on the discs, which can receive continuous light as the carousel rotates. However, the traditional disc radius is large and the spacing between discs is narrow, limiting effective light exposure to the microorganisms. This work considered the modifications to the disc design to enhance light efficiency. This point is the key novelty of this work, which should be highlighted in the end of the introduction.
(2)Authors are suggested to provide the working and structural parameters of the RBC in Figure 1.
(3)Equation 5 should be shortened to fit the formatting of the manuscript.
(4)Why MLSS has a minimum value in 100th day in Figure 4?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors have revised accordingly.
Author Response
Dear reviewer：
Thank you for taking the time to review our manuscript titled Light Enables Partial Nitrification and Algal-Bacterial Consortia in Rotating Biological Contactors: Performance and Microbial Community. We appreciate your valuable feedback and suggestions.
Your sciencerely,
Zichun Yan and Zhibin Pei
