Performance Comparison of Conventional and Modified Upflow Anaerobic Sludge Blanket (UASB) Reactors Treating High-Strength Cattle Slaughterhouse Wastewater

Round 1

Reviewer 1 Report

The manuscript aims to evaluate the effect of OLR on a conventional and a modified UASB reactors during treatment of CSWW. The subject and the findings of this study are interesting and its presentation is acceptable. However there are some points that needed to be improved before being accepted for publication

1) The status of English language is rather moderate (several grammatical and syntax errors can be found throughout the manuscript) and needs to be checked and improved by a native speaker.

2) Lines 74 and 76. Please use the same type of units

3) Line 78 Please use one decimal when reporting temperature values

4) I would recommend to the authors to integrate section 2.3 with section 2.1

5) title of section 2.4 Analytical Methods (instead of Analytical Method)

6) Line 95 Please use 'evaluate' instead of 'study'

7) Line 112 Please use 'slight' instead of 'little'

8) I am a bit confused regarding the influent COD concentration to both systems. According to Table 1 and several references in the text (e.g. lines 195-196) the feed COD concentration ranged between 3,5 and 32 g/L. However Table 2 presents values between 1.75-16 g/L and a dilution factor of 1 which practically means that the reference COD concentration of CSWW is 16 g/L and not 32 g/L (as presentd in Table 1). Please explain

9) According to the authors reactor R2 over-performed by exhibiting almost 80% COD removal even at the real influent COD concentrations (32 g/L). I am wondering how realistic is this as it practically corresponds to an effluent COD concentration of more than 6 gCOD/L?

Is this value comparable to the National effluent limits? Based on this, which are the practical implications of the results of this study? 

10) How do the authors verified the presence of the referred micororganisms in the sem photos?

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Author Response

Thank you very much for your wonderful contribution. I find your comments very interesting and knowledge impacting. I have uploaded the revised version of the manuscript for your kind consideration.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments:

Line 25, COD should be moved to behind the “g” in unit gL-1d-1.

Line 28, it says “methanosaeta spp” is stressed and line 354 says “the morphology of the image in fig.9(b) showed poorly active methanosaeta spp,…”. Please use reference to approve your judgement. I am not convinced about the statement purely based on a picture. Please indicate how to evaluate whether the microorganism is stressed.

Line 57, the Parentheses are missing for “SWW”.

Line 97, the word of “wastewater” is missing behind of “slaughterhouse”.

Line 111 and 112 should use the same metric unit for heights. “Inches” should be converted to “cm”.

Line 118, the world “where” should be deleted.

In Table 2, the feed COD and corresponding OLR get mixed up. It should be the opposite.

Line 185 and 197, the first “was” should be replaced with “were”.

The names of BOD and BOD5 are appearing simultaneously. I think BOD should be written as “BOD5”

Line 204 and 250, “VSS/TSS” is mentioned, there is no VSS method included and no data to support that.

Line 228, something is wrong with “10 16gL-1d-1”.

Line 240, the sentence should be rewritten since it is confusing.

Line 243, add “OLR’ after “this” to be clear.

Line 264, “forming” should be “foaming”.

Lien 283 to 285, this statement needs to have reference.

Line 297, double “at OLR”s are showing here.

Line 299, acids should be added after “volatile fatty”.

Line 311, the second “the” should be eliminated.

Line 315, the word “continuous” should be “continues”.

Line 321, “rector” should be written as “reactor”.

Line 321, “… and favorably treat color wastewater as against R1” is very misleading.

The sentence from line 325 to line 328, is not related to the discussion about color removal efficiency.

The sentence from line 363 to line 366 uses double negatives, “could not be unconnected”, which is very confusing. Hopefully it can be rephrased.

Table 3 is missing the title.

Line 409, “subside” should be “subsiding”

Author Response

Thank you very much for your kind and wonderful contribution. Sincerely, I find your comment very interesting, full of knowledge and wisdom. Please find attached a copy of the revised manuscript for your kind consideration.

Author Response File: Author Response.pdf

Reviewer 3 Report

Abstract

UASB should be presented fully, and use the abbreviation in the follow section.

The format of microbial names need to be revised.

1. Introduction

 the advantages or potential for treating SWW should be presented in the last paragraph, it it better to explain the mechanism for this method. 

2. Materials and Methods 

section 2.2 Substrate and seed inoculum should be set as 2.1 instead of the 2.1 Experimental set up.

 section 2.4 and 2.5 can be combined.

4. Conclusions

   This section should generally conclude the results, do not present the detail value obtained in this study.

Author Response

Than you very much for this wonderful contribution. I really benefitted a lot from your comments. They are full of knowledge and wisdom. Please find attached a copy of the revised manuscript for your kind consideration.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The revised form of the manuscript fulfills all my comments. Therefore I suggest its acceptance for publication