Straw-Based Biopurification Systems to Remove Ibuprofen, Diclofenac and Triclosan from Wastewaters: Dominant Microbial Communities
Round 1
Reviewer 1 Report
Dear Editor,
Dear Authors,
In my view paper “Straw based biopurification systems to remove ibuprofen, diclofenac and triclosan from wastewaters: Dominant microbial communities” by Delgado-Moreno et al. touches actual topic, describes well-designed and well-performed experiment and is written in well scientific style. In general, the paper deserves publication in Agronomy. At the same time in my view some issues need to be clarified prior acceptance.
Lines 294-297 – it is written that abiotic degradation could be due to incomplete sterilization – so, in fact, it also could be biotic degradation (at least in part). Also, it is suggested that photodegradation occurred – but the incubation was performed in the dark – so how photodegradation was possible? Explain, please. Was sterility of the sterile controls inspected in any way?
Section 3.5.1 and below – were the data rarefied for analysis (meaning was the analysis of the subsamples with equal number of reads performed)? Indicate it, please. Otherwise, the differences could be caused by different numbers of reads obtained at sequencing. Also, it would be great to indicate some basic data related to statistical sample volume – numbers of reads analyzed, coverage. It is partially indicated in line 461 (but only regarding average number) – it would be great to move it above, and indicate the volume of the smallest library. Otherwise, questions about sample sizes and coverage arise from the very beginning of Section 3.5.
Lines 472-476 - it is indicated, that sum of Proteobacteria, Actinobacteria and Bacteroidetes in SVS was 61% and sum of Crenarchaeota (Archaea), Acidobacteria, Chloroflexi, Firmicutes, and Planctomycetes in SVS was 7.58%. In total it is ~69%. It arises the question, which bacteria accounted the last ~31%? And the same about SAS and SPS mixtures.
Line 475 – typo – Plantomycetes change to Planctomycetes.
Lines 582-584 – such clustering also could suggest succession, which led to formation of microbial communities resistant to (or able to degrade) PPCPs.
Figure S2 – it indicated in the caption, that rarefaction curves for all mixtures are presented, but in fact there are curves for SPS only. Please add name of the y-axis.
Figure S3 – the letters marking significance of differences are presented on all panels excluding Bacilli – why it is absent for Bacilli?
Table 1 – typo – “ulvic” change to “fulvic”
Line 157 – 932% - is it typo?
Recommendations below in my view are not crucial for the paper acceptance, but it could improve the paper presented or could be taken into account for further work.
It would be great to define which taxa are mainly responsible for the samples clustering (or e.g. to perform PCoA or NMDS analysis and define which OTU/taxa are mainly responsible for ordination) – it could give important additional data and allow to reveal the main microbial groups able to degrade (or resistant to) PPCPs. It would be great to calculate and analyze beta-diversity indexes; comparing the indexes which are based/not based on phylogeny, which take/not take into account the abundance of the different microbial groups could help to reveal, were the differences caused by changes in microbial diversity, or by changes in community structure, was it caused by closely related taxa or not, etc. E.g. common for microbial ecology beta-diversity indices like Bray-Curtis, Sorensen, unweighted and weighted UniFrac could be fruitful.
Author Response
Thank you for your comments and corrections which have helped to improve the quality of the manuscript agronomy-1256780 entitled "Straw based biopurification systems to remove ibuprofen, diclofenac and triclosan from wastewaters: Dominant microbial communities".
Reviewer 2 Report
The manuscript describes the application potential of biopurification systems into the treatment of PPCPs by investigating the impact of biomixtures. It is very interesting that the composition of the biomixtures affected the PPCPs treatment, and the removal was depending on the organic carbon contents. If the following comments are reflected, the manuscript could be more improved.
Line #11.
In the Graphical abstract, the labels on the compositions of biopurification systems are not clear. For example, ‘S’ is used for both soil and straw. It would be better to provide the full description of the BPS microcosm groups from the beginning.
Line #54.
The Introduction section would be more convincing if the authors provide in-depth descriptions or previous studies on microbial communities in the BPS or other biological systems affecting PPCPs treatment.
Line #123.
What is the general range of the PPCPs (ibuprofen, diclofenac, and triclosan) detected from the environment? Mostly, the PPCPs have been discharged in low concentrations (e.g., ppb or ppt level) and they might be varied from the chemicals. The concentrations (25-250 mg Kg-1) used in the manuscript seem to be relatively high.
Line #137.
Typo: 20°C -> 20 °C
Line #154.
What were the limit of detections and limit of quantitation of the method for the PPCPs analysis?
Line #300.
Checking the line in Figure 1 is required. It seems that the TCS line in the SAS plot (the first graph) should be solid.
Line #322.
Compared to Figure 1 and Figure 2, the removal trends of TCS in all BPS do not seem to match the amounts of methyl triclosan. For example, in the SAS condition, the amount of TCS slowly decreased over the 80 days. However, methyl triclosan from the SAS began to show after 40 days. Could this be explained with microbial community analysis results? (Additionally, the line colors in Figure 2 are confusing with the symbol colors on PPCPs shown in Figure 1.)
Line #490.
Table 4: No horizontal lines in the right section of the table
Comments for author File: 
Comments.docx
Author Response
Thank you for your comments and corrections which have helped to improve the quality of the manuscript agronomy-1256780 entitled "Straw based biopurification systems to remove ibuprofen, diclofenac and triclosan from wastewaters: Dominant microbial communities".
Reviewer 3 Report
- What is the biobed biopurification system (line 54)? Consider expanding introduction a bit to explain this term.
- Lines 97-99: What caused this composition of the three mixtures?
- Lines 150-152: “To determine the degradation kinetic param-150 eters for the PPCPs in each biomixture, a single first order dissipation kinetics (Ct = Co x e-151 kt) was used.” Is it desirable to give a link to the source of the info?
4. Lines 157-158: how is it possible to extract more (up to 932%) of substance than it was initially? I am not very familiar with this method, so I am quite confused with such results. Please consider explaining that phenomenon in the text.
5. Line 200. The link does not work correctly. Please check it.
6. Line 202. What sequence homology percentage for OTU grouping? I think you should give it in the text.
7. Lines 288, 295 - not sterilized and not fully sterilized. Please check this information in the Methods section.
8. Color palette fig. 2a, it is desirable to change.
9. Line 584: apart from slower recovery of the microbiota there might be some crucial irreversible changes. Some microbial groups probably were completely displaced by the addition of PPCPs.
10. There are few language mistakes in the text. Please, read once through the text and correct them.
Line 60 “These carbon sources can served as…” should be re-written as “These carbon sources can serve as…”
Line 276 Was correlated
Line 559 SAP => SAS
Table1 lines 106-107. Consider re-writing FA –fulvic acids
Author Response
Thank you for your comments and corrections which have helped to improve the quality of the manuscript agronomy-1256780 entitled "Straw based biopurification systems to remove ibuprofen, diclofenac and triclosan from wastewaters: Dominant microbial communities".
