Conversion of Kitchen Waste into Sustainable Fertilizers: Comparative Effectiveness of Biological, Microbial, and Thermal Treatments in a Ryegrass Growth Trial

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The title of the proposed article should be revised to better reflect its content. The way it is presented here gives the impression that we are going to go into the production processes of these different fertilisers when we are only interested in their fertilising or non-fertilising properties.

 

The subtitles in the first part should be removed. There's a big section on compost, but nothing on anaerobic digestion. What are the general characteristics of digestate in terms of NPK? How many anaerobic digestion plants are there in Poland? Is anaerobic digestion of catering waste an industrial sector in Poland and if so, how many sites are involved?

L138. the term EM has already been defined

L109. Add reference.

The Materials and Methods section needs to be improved in several respects.

The abbreviation d.m., which should stand for dry matter, should be replaced by total solids.

Measurement uncertainties should be added to all tables and figures.

The measurement methods should be described before the results obtained using these methods are presented (see Table 1).

Similarly, the operating conditions for the methods used to obtain digestates, fertilisers, etc. (L232-243) in the table should be described before this table so that it can be understood.

Table 4 can be simplified, as most of the data are the same. Table 4 to be simplified

Have the scenarios and measures been triplicated?

Table 2 refers to an olfactory methodology, but no protocol is referenced. Delete this table if there is no protocol.

 

Specify the operating conditions of the tests more clearly, especially for anaerobic digestion. Is it liquid or dry? Is it stirred? What is the I/S ratio? What proportion of kitchen waste was used in the AD? Did the AD process run well? Was there an inhibition phase that could affect the composition of the digestate? Was there a co-digestate? What inoculum was used for DA?

L278 -287 add measurement uncertainties

L312. Delete title.

on all the graphs, delete the abbreviation d.m and enter total solid, i.e. TS

Put the standard deviation on the curves, they are not present on all the curves. this concerns all the figures.

the presence of equations on the graphs in figures 3 and 4 makes the graphs too busy.

Explain the transformation of mineral nitrogen into ammonium nitrogen in digestates

Figure 7 is incomprehensible without a legend. There are large bars and smaller ones of the same colour and it's hard to understand. Please make it easier to understand. The legend above is not clear and only indicates blue and grey.

L497. To be modified. Cannot end with:.

Studies on the agronomic properties of digestates should be added to the discussion. L485-491.

Author Response

Dear Editor

All the answers are contained in the attached file.

Regards

Authors

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors describe greenhouse experiments with organic waste from households (i.e. kitchen and food waste) that is inoculated by "effective microorganisms" (different concentrations, with or w/o foregoing sterilisation). The methods used and the results are presented in an intelligible form. Some unclear points have to be resolved:

• In the Abstract, chicken manure an cow manure are mentioned. From the experimental part I assume that only cow manure was used. Special abbreviations should not be used in the Abstract (or at least be explained like CMG)
• Mineral fertilizer is used for comparison. The results of this batch are only partially presented, e.g. not in Fig. 1-Fig. 3. This should be complemented or explained.
• The "control treatment" (line 401) is not described clearly in the methodology. 
• The effect of the different fertilizers on soluble N, i.e. potential loss into groundwater, should be discussed or - if there are no results - mentioned as a potential problem in the conclusion.

Author Response

Dear Editor

All the answers are contained in the attached file.

Regards

Authors

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have taken the comments into account and improved the document. This article can now be published.

The title corresponds better to the content.