Charcoal in Anaerobic Digestion: Part 1—Characterisation of Charcoal
, Ruth Freitag 2 and Volker Haag 3
Round 1
Reviewer 1 Report
The study examined various sources of Biochar (BC) in terms of raw materials, production processes, and structural, physical, and chemical properties. The characterization processes of the BC were thoroughly investigated and the results were successfully demonstrated. However, the main focus of the study, which is the impact of these characteristics on anaerobic digestion (AD) efficiency and stability in correlation with the studied characteristics, was not explored. In my opinion, it would have been more advantageous if the authors had used the samples of the studied BC in AD trials to correlate these characteristics with the efficiency and stability of the AD process.
The results of physical, chemical, and biological analyses are well described and presented, requiring no further details.
Author Response
Comment 1: The study examined various sources of Biochar (BC) in terms of raw materials, production processes, and structural, physical, and chemical properties. The characterization processes of the BC were thoroughly investigated and the results were successfully demonstrated. However, the main focus of the study, which is the impact of these characteristics on anaerobic digestion (AD) efficiency and stability in correlation with the studied characteristics, was not explored. In my opinion, it would have been more advantageous if the authors had used the samples of the studied BC in AD trials to correlate these characteristics with the efficiency and stability of the AD process.
Response 1: We changed the title into "Charcoal in anaerobic digestion: Part 1 – Characterization of charcoal" showing that the main issue is BC characterization. Results of BC in AD will be given in a second paper "Charcoal in anaerobic digestion: Part 2 – Influence of charcoal on anaerobic digestion”. If we would put all results in one paper, it would become too big.
Reviewer 2 Report
- Regarding Biblio: some bibliographical references are only in German, if possible supplement with updated English literature, thank you
- units of measurement: check in the text that they are always reported in the same format
- results: although very interesting, check and review the order of the information, sometimes paragraphs do not seem well connected
- beware of aconyms, replace names with their acronyms where possible (e.g. Biochar with BC)
All reported in red in attached file.
Q=Question
Comments for author File: 
Comments.pdf
Author Response
Comment 1: results: although very interesting, check and review the order of the information, sometimes paragraphs do not seem well connected
Response 1: The text passages marked in red in peer-review-38502014.v2.pdf (comments, questions, literature) were edited and integrated into the publication draft. Some comments got their response in the attached document carbon-3055983-review-3 Response.
Comment 2: some bibliographical references are from texts written only in German. Consider implementing some English articles in the bibliography.
Response 2: German titels now are transleted into english. Ref. 1 is the latest overview of biogas plants in Germany. There is no comparable english reference. Ref. 2 is a German statistical document. TZhere is no English version available. Ref. 10 and ref. 11 deal with same topics but Ref. 11 mainly describes american wood species. Ref. 13 is the only existing document, there is no English version. Ref. 17 was changed from a Germa Title to an English written reference.
Author Response File: Author Response.pdf
Reviewer 3 Report
- A more detailed discussion of the results presented in Figures 5 and 6 is highly recommended.
- SI units should be used throughout the manuscript.
The paper presented the production and characterisation of BC cubes of approximately 6 x 6 x 6 mm and rods of Scots pine (Pinus sylvestris) and beech (Fagus sylvatica) produced simultaneously in a 90L batch retort and commercial charcoal powder (CCP). It is a nice paper, worthy of publication in the C Journal of Carbon Research after minor revisions.
- A more detailed discussion of the results presented in Figures 5 and 6 is highly recommended.
- SI units should be used throughout the manuscript.
Author Response
Comments 1: - A more detailed discussion of the results presented in Figures 5 and 6 is highly recommended.
Response 1: results in Figures 5 and 6 are discussed in more detail.
Comments 2. - SI units should be used throughout the manuscript.
Response 2: all units have been changed to SI units.
