Biochar/Clay Composite Particle Immobilized Compound Bacteria: Preparation, Collaborative Degradation Performance and Environmental Tolerance
Anjie Li
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsI would like to congratulate the authors for this great, exciting work.
The figures and tables are clear and easy to interpret. The language of the work is understandable.
I found some errors, probably due to a typo. Please improve the formula of the compounds: NH4+-N.
Line 61 should not be dotted after Osborne's name.
In line 81, what does it mean that it was obtained from LRE?
In line 290, the letter “i” is missing from the word individual.
Author Response
Thank you for reviewing our manuscript and give us an opportunity to improve our manuscript. We have revised our manuscript carefully and the respond was as following:
[Q1] Please improve the formula of the compounds: NH4+-N.
Response：NH4+-N has been corrected to NH4+-N.
[Q2] Line 61 should not be dotted after Osborne's name.
Response：We have removed the points after Osborne.
[Q3] What does it mean that it was obtained from LRE?
Response：The background of our research is that the combined pollution of ammonia nitrogen and petroleum hydrocarbons in the Liaohe Estuary Wetland (LEW) is serious. In order to ensure the invasion of foreign species and obtain high-efficiency degrading bacteria in sediments contaminated with both ammonia nitrogen and petroleum hydrocarbons, we chose to screen high-efficiency degrading bacterial communities in the sediment of the LEW. In addition, reeds and clay also come from the LEW to achieve efficient utilization and industrialization of resources.
We have made a shorthand error and revised in the manuscript.
The manuscript has revised as following:
The Liaohe Estuarine Wetland (LEW) is an important crab breeding area and also a reused oil extraction area.
Clay and reed stalk materials were obtained from the LEW.
[Q4] In line 290, the letter “i” is missing from the word individual.
Response：The individual has been corrected
Reviewer 2 Report
Comments and Suggestions for AuthorsThe study used BCCP as immobilized microbial material of AOB and some heterotrophic bacteria to remove ammonia and PHCs from natural water. The idea is interesting and deserves to investigate. But there are still some issues that need to be clarified and improved.
1. Why did the author mention wetlands in the introduction? Will BCCP-immobilized bacteria be used in wetlands?
2. What is the size of BCCP? Is it feasible to immobilize BCCP in SA+PVA? Please provide images of the immobilized particle.
3. The author used SA and CaCl2 for gel particle formation. What is the function of PVA?
4. Section 2.5, please clarify the set-up of degradation experiment. Is it a batch test? Did the authors add ammonia and PHCs in the system only once or every day?
5. About the adsorption capability of ammonia by BCCP, please compare with other adsorption agents to show the advantage of BCCP. Besides, adsorption capability of BCCP might change after BCCP was immobilized in SA+PVA.
6. Please revise Figure 3 which is not good to show the difference among samples.
7. The author should provide analyses of bacteria or microbial activity to show the effect of BCCP on bacteria growth.
8. Figure 4, only one data of removal efficiency. How to use one data to show two parameters (ammonia and PHCs)?
9. Please provide error bars for all data to show the statistically significant difference.
Comments on the Quality of English Language
Minor editing of English language required
Author Response
[Q1] Why did the author mention wetlands in the introduction? Will BCCP-immobilized bacteria be used in wetlands?
Response：The background of our research is that the combined pollution of ammonia nitrogen and petroleum hydrocarbons in the Liaohe Estuary Wetland (LEW) is serious. In order to ensure the invasion of foreign species and obtain high-efficiency degrading bacteria in sediments contaminated with both ammonia nitrogen and petroleum hydrocarbons, we chose to screen high-efficiency degrading bacterial communities in the sediment of the LEW.
In addition, the LEW is located in northern China and is affected by the low temperature, high salinity and tides. The application of high-efficiency degrading bacteria is a challenge. Therefore, immobilization methods with BCCP do not only resist low temperature and high salinity, but also avoid being dispersed by tides in the wetland.
[Q2] What is the size of BCCP? Is it feasible to immobilize BCCP in SA+PVA? Please provide images of the immobilized particle.
Response：The average size of BCCP is 10mm. It is feasible to immobilize BCCP in SA+PVA. The image is as following.
[Q3] The author used SA and CaCl2 for gel particle formation. What is the function of PVA?
Response：SA and PVA are both embedding materials, and CaCl2 is used to prepare gel particles. BCCP is added to the embedding mixture and then moved into the CaCl2 solution to form gel particles. In our previous research, we found that the combination of PVC and SA can achieve better results (Sun et al., 2022).
Sun, P., Huang, X., Xing, Y., Dong, W., Yu, J., Bai, J., and Duan, W. (2022). Immobilization of Ochrobactrum sp. on Biochar/Clay Composite Particle: Optimization of Preparation and Performance for Nitrogen Removal. Front. Micobiol. 13. doi: 10.3389/fmicb.2022.838836.
[Q4] Section 2.5, please clarify the set-up of degradation experiment. Is it a batch test? Did the authors add ammonia and PHCs in the system only once or every day?
Response：The set-up of degradation experiment has been clarified in the manuscript and it is not a batch test. We add ammonia and PHCs in the system only once.
[Q5] About the adsorption capability of ammonia by BCCP, please compare with other adsorption agents to show the advantage of BCCP. Besides, adsorption capability of BCCP might change after BCCP was immobilized in SA+PVA.
Response：In our previous studies (Sun et al., 2022), we have demonstrated that BCCP has excellent adsorption performance when applied to adsorption materials such as Biochar. BCCP can withstand the influence of environmental factors and has good adsorption effect. In manuscript, we have proved that the adsorption capability of BCCP increased after BCCP was immobilized in SA+PVA.
Sun, P., Huang, X., Xing, Y., Dong, W., Yu, J., Bai, J., and Duan, W. (2022). Immobilization of Ochrobactrum sp. on Biochar/Clay Composite Particle: Optimization of Preparation and Performance for Nitrogen Removal. Front. Micobiol. 13. doi: 10.3389/fmicb.2022.838836.
[Q6] Please revise Figure 3 which is not good to show the difference among samples.
Response：Figure 3 has been corrected in the manuscript. As shown below
[Q7] The author should provide analyses of bacteria or microbial activity to show the effect of BCCP on bacteria growth.
Response：Thank you for the reviewer's suggestion. This is a very important indicator, and we have also attempted to verify the activity of immobilized microorganisms, which can better support our results. However, we were unable to separate them after microbial immobilization, resulting in unsatisfactory test results. We will continue our research and strive to publish the paper on a separate topic in future research.
[Q8] Figure 4, only one data of removal efficiency. How to use one data to show two parameters (ammonia and PHCs)?
Response：Figure 4 is a combination of NH4+-N removal by Aquamicrobium sp. and PHCs removal by Flavobacterium mizutaii sp., so two parameters can be shown.
[Q9] Please provide error bars for all data to show the statistically significant difference.
Response：All data Error bar have been added to the original text.
[Q10] Please correct the grammar mistake in the article.
Response：Some grammar issues in the article have been corrected. The specific corrections are as follows:
The adsorption method has a wide application range and good treatment performance.
Flavobacterium mizutaii sp. was reported as a predominant bacterial genus in the denitrification process and can effectively degrade NH4+-N in water [4]. Aquamicrobium sp. was found to be effective in degrading alkanes [5].
Meanwhile, environment factors such as salinity and temperature restrict pollutant degradation and it is necessary to study the degradation of pollutants by immobilized bacteria technology in wetlands [6].
When the temperature is lower than the optimal temperature, it affected the growth rate of bacteria, while higher temperatures reduced protein activity and even lead to cell death [8].
Reddy and Osborne (2020) immobilized the Pseudomonas guariconensis in the biocarrier matrix to degrade Reactive red 120, and the degradation efficiency could reach 91% [10]. Yan et al. (2020) found that the degradation efficiency of Ca2+ and Mg2+ can reach 90% and 70% under the action of immobilized Lysinibacillus fusiformis DB1-3 bacteria [11].
In addition, the LEW is located in northern China and is affected by the low temperature, high salinity and tides. The application of high-efficiency degrading bacteria is a challenge. Therefore, immobilization methods with BCCP do not only resist low temperature and high salinity, but also avoid being dispersed by tides in the wetland. Immobilized BCCP is an effective method to solve the above problems, and its tolerance to low temperature and high salt needs to be further explored.
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors have tried their best to revise the manuscript.
