Study on Aeration Optimization and Sewage Treatment Efficiency of a Novel Micro-Pressure Swirl Reactor (MPSR)
Round 1
Reviewer 1 Report
A very interesting paper, which will be of use in a number of areas.
High variability in the standard of English in different sections.
Check on your statement on SRT.
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewer 1 Comments
Point 1: A very interesting paper, which will be of use in a number of areas.
Response 1: Thank you very much for your recognition and support of our work. At the same time, I would also like to thank you for your careful and patient reading of this manuscript. Your English revision of this manuscript has greatly helped to improve the quality of this manuscript.
Point 2: High variability in the standard of English in different sections.
Response 2: I am very sorry for the bad reading experience, and unfortunately tell you that the English writing of this manuscript was done by myself. Because English is not proficient enough, my grasp of tense and voice is often inappropriate. Based on your language question, I have made changes in the revised draft. I have tried to make the article smooth, but there are inevitably problems. This requires your continued correction, I am felt sorry and disturbed.
Point 3: Check on your statement on SRT.
Response 3: Based on your prompt, we reviewed and modified the part describing the SRT. The revised department is located on lines 146-148, 164-169, and Table 2 of the revised manuscript. But it is worth noting that the part of the problem you pointed out does not involve SRT issues. Described here is the experimental process of the dissolved oxygen distribution in the main reaction zone. We hope to keep the sludge concentration in the reactor at about 4000 mg / L through activated sludge backflow, sludge concentration detection and sludge discharge. For the dissolved oxygen distribution test, it is necessary to ensure a stable sludge concentration, because it is impossible to compare the dissolved oxygen distribution of different sludge concentrations at different aeration rates.
Author Response File: 
Author Response.doc
Reviewer 2 Report
Study on aeration optimization …. (MPSR) by Shengshu et al..
This manuscript describes the efficiency of a novel micro-pressure spiral reactor on sewage treatment in an in-vitro set-up which is quite an interesting technique. The study has been conducted in a scientifically sound manner and the design and results are analyzed and described in a very clear manner. The English is quite good but I only have a suggestion that the description of the results is quite long and need to be quite shortened. The contour figures are good to understand the distribution of oxygen and other parameters in the pressurized micro pressure reactor. I have the following recommendations:
- It is unclear to me how the samples were collected for microbial analyses. How samplings were collected from difference zones of MPSE aseptically? And timing of their collection? As it is evident that with time the circulation patterns changes, DO changes and these will have a significant impact on the microbial distribution within the reactor. The results are very interesting though.
- The changes in nutrient load and COD are also interesting between the influent and effluent waters, but how did these parameters play into each other and their impact on the distribution of microbial community.
- The discussion section is very poor. It is just a synopsis of the work. This needs to be discussed in context of the work done so far and how this is going to impact the sewage treatment.
Author Response
Response to Reviewer 2 Comments
Point 1: It is unclear to me how the samples were collected for microbial analyses. How samplings were collected from difference zones of MPSE aseptically? And timing of their collection? As it is evident that with time the circulation patterns changes, DO changes and these will have a significant impact on the microbial distribution within the reactor. The results are very interesting though.
Response 1: First of all, thank you for your affirmation and support for this manuscript. I would like to explain to you the collection of microbial community test samples. As you said, over time, the circulation pattern will change and the DO will change, which will have a significant impact on the distribution of microorganisms in the reactor. However, the state you said will occur when the MPSR is in the sequential batch mode. When the MPSR is in the continuous flow mode, this effect will be relatively small. The microbial samples obtained in this study were performed in a continuous flow mode of the reactor. Continuous flow mode is different from sequential batch mode, the DO distribution and microbial distribution in the reactor are less affected by time. At the same time, when sampling at points 1-5 and 7-5, due to the fast flow rate, we took two people to take samples at the same time, and when sampling at points 4-3, 4-5, and 4-7, due to the lower flow rate, the sampling operation performed by one person, which may cause certain errors.
Point 2: The changes in nutrient load and COD are also interesting between the influent and effluent waters, but how did these parameters play into each other and their impact on the distribution of microbial community.
Response 2: These are what we will study next. In this research, we mainly want to show our MPSR. The flow velocity distribution test shows that it can form a stable circulating flow pattern in the center of the reactor, which meets the requirements of the aeration tank stirring function. The dissolved oxygen distribution test shows that under the conditions that the volume of the tank is determined and the sludge concentration and the quality of the incoming water are relatively stable, the aerobic, anoxic, and anaerobic coexisting state in the reactor can be achieved by adjusting the aeration amount, Realize the idea of MPSR. The sewage treatment test confirmed that MPSR can operate in continuous flow mode and sequential batch operation mode, and at the same time, the effluent meets the requirements of China's rural pollution control at this stage. Finally, through the detection of microbial flora in continuous flow mode, it was confirmed that MPSR can achieve spatial differences in the distribution of microbial communities through different DO and water flow environments. Subsequent detailed research requires our further work.
Point 3: The discussion section is very poor. It is just a synopsis of the work. This needs to be discussed in context of the work done so far and how this is going to impact the sewage treatment.
Response 3: I'm very sorry for the bad reading experience. Because of the lack of experimental data, I considered that too many relevant comments may lead to lengthy and exaggerated articles. I didn't expect that my consideration would make the level of the paper drop. According to your requirements, we have further written the paper. The relevant amendments are located on lines 259 ~ 266 and 315 ~ 328 of the revised manuscript. Thank you very much for your suggestions. Your related comments have greatly helped the quality of the paper.
Author Response File: Author Response.doc
Round 2
Reviewer 2 Report
Still I am not satisfied with the modification especially on the methodology of collection of microbiological samples and the discussion part.
Author Response
Response to Reviewer 2 Comments
Point 1: Still I am not satisfied with the modification especially on the methodology of collection of microbiological samples and the discussion part.
Response 1: I apologize for the last revision that did not satisfy you, and thank you again for your valuable suggestions for this manuscript. Here, I would like to make a small discussion with you based on your two amendments. This section is mainly about microbial testing. First of all, I would like to emphasize a premise that we collected and detected microbial samples when MPSR was in continuous flow operation mode. Here we wanted to study the differences in the spatial distribution of microbes in MPSR. Due to the severe mixing of activated sludge during the settling, feeding and aeration stages in the sequential batch operation mode, we cannot achieve the expected research goals in this state. At the same time, when MPSR was in continuous flow operation mode, under the premise that the activated sludge concentration was basically stable, the aeration was constant, and the inflow and return sludge flows were constant, we tended to agree that the environmental conditions that affect the survival of microorganisms such as DO distribution, hydraulic conditions, and pollutant distribution in the reactor were basically in a relatively balanced state. At this time, it is a relatively ideal state to study the differences in the spatial distribution of MPSR in microorganisms. Secondly, I would like to explain further our collection of microbial samples. In the response to the last revision, I had explained in detail our sampling process of biological samples. Because of the flow velocity, points 1-5 and 7-5 were operated by two persons at the same time when sampling, and points 4-3, 4-5, and 4-7 were performed by one person at the time of sampling. I understand your concerns very well. With the internal circulation of MPSR, the sample taken at a certain time is often not the sample at this point, because the microorganisms at this point have moved forward with the cycle. For this reason, we cannot do better. We can only ensure that the gloves and sampling tube are sterile when sampling. By the way, the volume of our sampling tube is 10mL, and the sampling is generally completed within 2~3s. However, it is worth noting that the lag in sampling time has little effect on the results of microbiological studies. Due to the solid phase participation of activated sludge, the viscosity of the mixed liquid increases, and the differentiation of the velocity distribution area in the MPSR becomes very obvious. The flow speed of the outside of the reactor due to aeration was faster, and the speed in the central area was almost zero due to the significant increase in viscosity. Correspondingly, the flow velocity in the reactor was lower than that in the flow velocity distribution test also due to the viscosity force. Therefore, the low circulating flow rate and more obvious partitioning make the effect of sampling in a short time negligible. In addition, we agree that sample accuracy caused by the lag in sampling time has no fundamental effect on the conclusions drawn. From the structure of MPSR, it can be seen that when MPSR was in continuous flow operation mode, the material exchange in different areas was mainly the turbulence of the four apex angles of the reactor and the diffusion of water. At the same time, in order to avoid too fast material exchange, we chose sampling points close to the center of the reactor to avoid the four apex angles. The diffusion of the inflow water at the center point was also relatively slow due to the flow velocity limitation. Therefore, the effect of sampling lag on sample quality was relatively small. In addition, we have revised the discussion part again, and the revised part is located in the revised version of lines 462~475. Thanks again for your suggestions.
Author Response File: Author Response.doc
