Aquatic Plants, Landoltia punctata, and Azolla filiculoides as Bio-Converters of Wastewater to Biofuel

Round 1

Reviewer 1 Report

This manuscript addresses an aquatic plants’ functions to simulate with an operation as for bio-converters of wastewater to biofuel, which is still relatively interesting and is of great current concern to those dealing with treatment data associated with water quality from previous documents. The content of the publication deals with an older problem of wastewater controls and nutrient removals. Nevertheless, the problem and the perspectives are very topical and can make a very significant contribution to solving current problems, i.e., Se concentrations. The efficient aquatic plant restoration of reclaimed wetland can provide very important approaches to solving the need for biofuels. The parameters studied were perfectly analyzed, but may also play a role in assessing aquatic plant management. These could possibly move more into the focus of consideration in the future. I found the manuscript insufficiently original but interesting to warrant future publication after it is revised. Please revise your manuscript that what is the major contribution compared to the previous studies? Did the authors have more findings from the hypothesis. Some comments as indicated as follows.

1. Do you have any dry weight data for the aquatic plants? Was there any significant effect of Se on the plant growth?
2. The authors needed to water the pot once a while to keep plants and shrimps alive during the experiment. Is it possible that some of the Se in the soil might have leaked from the bottom of the pot with the access water? If so, have the authors considered it a loss or included in the “unaccounted for” component?
3. Sulfate might compete for plant uptake with selenate due to their chemical similarity. Did you add any nutrients to the pot (i.e., microcosm) during the experiment?
4. Selenium was detected in the species, accumulated in L. punctata and A. filiculoides biomass, in the control group. Where did the Selenium come from? Were the species contaminated before the experiment? Please confirmed.
5. What do “STD” and “SeSW” mean in the figures? I’d suggest they should be spelled out in all the Figure captions or Table captions to make them more understandable.
6. There’s some mortality and survival rates of P. australiensis observed in each pot. Had the authors measured Se levels in dead earthworms, or just dead shrimps? Or they were missing or unrecognizable by the end of the experiment so the Se that might had been accumulated in the dead shrimps was included in the soil Se section?
7. Is there any reason for choosing L. punctata and A. filiculoides as an alternative carbon source for the study? The authors might have to clarify it more in the introduction.
8. Please define all terms throughout your manuscript upon first reference, e.g., explaining the DW in your abstract (Line 24).

Author Response

Pls see an attachment

Author Response File: Author Response.docx

Reviewer 2 Report

Introduction.
from 94 to 107 ... this part distracts from understanding the objective of the work which must be clearer and more immediate ...

Author Response

We are grateful for this comment and all requested parts were improved

Reviewer 3 Report

This is an interesting work about the potential bioenergy  by sequential treatment by Azolla filiculoides and Landoltia punctata as feedstock of utilitary oleaginous heterotrophic microorganisms and H2 biofuel production.

There are only some corrections to do. In lines 474, 479, 482, 548, 635, 650, 660, 663, 691, 694, 710, 730, 743 and 744, the jorunal names should be given in the abbreviated form.

Author Response

We are grateful for these comments all requested parts were modified