Removal of Micropollutants by Ozone-Based Processes

Round 1

Reviewer 1 Report

I have to read your manuscript with great attention and interest. The material is consistent, comprehensive and complete.  However, please take into account some of my comments:

-Fig. 1, please provide the literature source, 

-Figs 2 and 3 present the author's own research? I request information

-Please provide information about the costs of the process in a few sentences (it can be compared to other methods from the AOP)

Author Response

Review 1

English language and style

( ) Extensive editing of English language and style required
( ) Moderate English changes required
( ) English language and style are fine/minor spell check required
(x) I don't feel qualified to judge about the English language and style

Comments and Suggestions for Authors

I have to read your manuscript with great attention and interest. The material is consistent, comprehensive and complete.  However, please take into account some of my comments:

-Fig. 1, please provide the literature source, 

Figure 1 was made by Andrej Žgajnar Gotvajn and her colleague, based on various reviews. References [27, 49, 114, 117, 120] have been added to the description of Figure 1.

-Figs 2 and 3 present the author's own research? I request information

Figures 2 and 3 are part of unpublished research of authors as an example of effective decolorisation in ozonation experiments with industrial pharmaceutical wastewater. This information was added in the manuscript. (Lines 237-240)

Please provide information about the costs of the process in a few sentences (it can be compared to other methods from the AOP)

The following text was added into manuscript (Lines 1406-1422):

For assessment of feasibility of ozonation and ozone-based process prices of ozone production should be considered. They depend upon type of the ozone generator, ozone dose required for effective removal of target pollutants as well as on actual price of other chemicals (hydrogen peroxide, catalysts, etc.) and energy used (UV, etc.). Regarding estimating average price 0.339 EUR per mg of O₃ produced optimization of the process of water treatment is highly recommended. The same this is also true for waste sludge processing using ozonation [74]. Ozonation of waste sludge prior anaerobic digestion helps to mainly increase the first step of the process, hydrolysis to increase biogas production and methane yield. However, increased production of the methane due to such pretreatment should be considerable regarding the incineration of formed methane and its energetic value (heating value of 50 MJ kg^-1). Due to the average energy price in EU for non-household consumers (0.135 EUR per kWh; Eurostat, 2020) the rationale between price of ozone production and improved energy production should be always addressed. Many authors confirmed that the optimal ozone dose for sludge solubilization is in the range of 0.05 to 0.5 g O₃ g^-1 of total solids, depending on the properties of the sludge and other conditions of the selected pretreatment method [74, 188].

Author Response File: Author Response.pdf

Reviewer 2 Report

The review is excellently written, very good concept, easy to understand and follow what the authors had in mind. There are few comments as suggestions for further improvement of the manuscript.

Comments for author File: Comments.pdf

Author Response

English language and style

( ) Extensive editing of English language and style required
( ) Moderate English changes required
(x) English language and style are fine/minor spell check required
( ) I don't feel qualified to judge about the English language and style

Comments and Suggestions for Authors

The review is excellently written, very good concept, easy to understand and follow what the authors had in mind. There are few comments as suggestions (peer-review-12175535.v2.pdf) for further improvement of the manuscript.

It would be more interesting and clear if you could classify above mentioned organisms into special groups (lines 1571 - 1575, e.g. bacteria, fungi, yeast, mold etc.) Also I do not see the references for all listed organisms. Please add references.

The mentioned organisms were cited according to reference [204] as bacteria, however we classified them correctly in our manuscript (Lines 1518-1524). Bacteria, such as Sphingomonas, Sphingobium, Pseudomonas, Pseudoxanthomonas, Thauera, Novosphingonium, Bacillus, Stenotrophomonas, Clostridium, Arthrobacter, Acidovorax, Maricurvus, Rhizobium, Corynebacterium, Rhodococcus, Burkholderia, Acinetobacter, fungi such as Aspergillus, Pleurotus, Trametes, Clavariopsis, Phanerochaete, Bjerkandera, Fusarium, Metarhizium, yeast Candida, and mould Mucor have been reported as efficient for degradation of NP via its metabolic pathway. The reference [204] was also added in the text.

It would be very good if authors add table with the list of used abbreviations in the text and write their full meaning. In this way, it would be easier for reader to precisely find the meaning of abbreviation he/she is interested in, without going through all the text.

The table with the list of used abbreviations in the text and their full meaning was added (Line 1907).

Please check/edit references so they have recommended style. Note that some reference do not have doi and some of references have hyperlinked doi.

The references were checked/ edited regarding the recommended style. Missing doi numbers were added, hyperlinks were removed from the text. The references were also renumbered due to addition of some new references according to suggestions of the reviewers.

English language and style are fine/minor spell check required.

The manuscript was revised, English language, style and typos were edited and corrected.

Corrections of misprints

Some misprints (brackets, dots, commas, subscripts, Latin names of organisms in italics, full stops, missing words, etc.) were corrected directly in the text.

Author Response File: Author Response.pdf