3.2.3. The influence of combined alkali pre-treatment and enzyme
addition
The addition of enzyme caused no significant improvements to
biomethane production from Ca(OH)2 pre-treated wheat straw. On
the contrary, in the initial digestion period the application of
enzyme to Ca(OH)2 pre-treated straw significantly reduced the biomethane
production from the 3 mm wheat straw by 12.3%.
Unexpectedly, the average final biomethane potential yield
recorded from 10 mm Ca(OH)2 pre-treated wheat straw was
20 ± 14 NmL g-VS1 less after the addition of enzyme. The lack of
improvement in the biomethane potential yield from the
combined alkaline pre-treatment with enzyme addition to the
anaerobic digestion of wheat straw, shows that the increase in
biomethane potential yield caused by enzyme supplementation
alone becomes redundant after Ca(OH)2 pre-treatment.