pH-Based Control of Anaerobic Digestion to Maximise Ammonium Production in Liquid Digestate

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The authors set the stage to investigate the ammonia production rates in batch anaerobic digestion under different control pH control strategies. The pH of the AD was controlled at three different set points for three different substrates. This was achieved by using two different set-ups; the DDS and the CDS. Authors discovered that pH of 7 is the optimal set point for both ammonium release and gas production rate. In addition, CDS presents enhanced gas rates compared to DDS. This study seems interesting, but there are some issues that have to be addressed.

1) The authors tested three (3) only separate feeds for their experiments. Have the authors tested more than these 3 feeds? For example, banana peels only sample and/or a sample with the three substrates (banana, cow dung and lentils).

2) The sample 3 (lentils and cow dung) was tested only for the DDS method (Table 2).  Would not make a difference in ammonium concentration and gas production rate if CDS method is used?

3) The NaOH amount, the ammonium concentration and gas concentration are quantified (Fig. 8-10)? An average value should be given for these metrics in order the authors to have a fair comparison between DDS and CDS methods (use of a table). 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

 English language and References are fine/minor spell check required

Reviewer 2 Report

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