Optimizing ADM1 Calibration and Input Characterization for Effective Co-Digestion Modelling

Round 1

Reviewer 1 Report

In general, this is a well-written article. However, more can be done to improve its quality. Authors are advised to revise based on the following comments.

1. No reference cited in this work is published in year 2020 and 2021. Authors should quote up-to-date references to reflect to importance of this study in Introduction.
2. Some of the tables are not necessarily included in main text. For instance, Table 1 and 3 can be arranged in supplementary file.
3. Figure 3(b) – Please explain why PR_TKN was excluded from the figure.
4. Figure 4(c) – Please explain why the experimental hour was much shorter (only 140 h).
5. Section 4 – Authors should compare the findings with up-to-date studies.
6. Conclusion is too short and there is no highlight at all on the key findings (in number/value). Besides, authors are advised to include recommendation (for future work) at the end of this section.

Author Response

Please see the attachment.

Best regards,

Arianna Catenacci

Reviewer 2 Report

The reviewed manuscript is significant and interesting from a theoretical and practical point of view. Anaerobic digestion of waste sludge from municipal wastewater treatment plants is the most efficient way of sludge treatment. In addition to purified wastewater stabilised sludge represents an additional value in the form of produced energy usable biogas. Anaerobic co-digestion of organic waste, in addition to its treatment, it also contributes to the energy benefits of the wastewater treatment plant in question.

 

ADM1 presents as a state of art in mathematical modelling of aerobic digestion of organic substrate. However, the use of this model requires characterizing the substrate composition and the values ​​of the kinetic parameters of the model.

The authors of the paper present a proposed and verified combined protocol, including tests of biochemical potential of methane and analytical determinations, which was applied to characterize the inflow of substrates for simulation of anaerobic pilot-digester in which co-digestion of waste sludge and expired yogurt was operated. They have also developed and verified an iterative procedure to improve the adaptation of dose tests to identify kinetic parameters.

The work has a logical structure and is written transparently. The results show that the iterative procedure significantly improved the adaptation of the alkalinity model, total volatile fatty acids, pH, COD, volatile solids and ammonium nitrogen  within the scope of the performed iterations.

The results show that the proposed and verified procedure for characterization of the input state variables of the ADM1 program is effective. The iterative calibration procedure of this model improves the quality of its prediction.

The authors also predict the expected further improvements, which motivates further research in this field.

 

Author Response

Please see the attachment.

Best regards,

Arianna Catenacci

Author Response File: Author Response.docx