The biochemical methane potential and composition of sugar beet pulp silage were investigated using samples taken from six different depths in both open and closed silos (height 3.6 m). The biochemical methane potential (BMP) of pulp silage in open silos ranged from 337 to 420 normal litre (NL) CH₄/kg volatile solids (VS), while the BMP of pulp silage in closed silos varied between 411 and 451 NL CH₄/kg VS. The biochemical methane potential peaked at a depth of 1.45 m with 420 NL CH₄/kg VS for open silos and 451 NL CH₄/kg VS for closed silos. The ethanol concentration and biochemical methane potential showed the same trend with depth throughout the silos. The energy loss correlated to the loss of volatile solids, and the depths described a linear relationship between them for both the open and closed silos (R² = 0.997 for the open silo and R² = 0.991 for the closed silo). The energy potentials and composition of beet pulp silage were highly stratified and there was a risk that the silage samples were not representative in investigations of biomass quality for energy production.

This study investigated biogas production as an alternative treatment of tannery wastewater (TWW) and its use as a pre-treatment medium to increase CH₄ yield from anaerobic digestion (AD) of wheat straw. The TWW had high levels of sulfate and chloride, so biochemical CH₄ potential could be estimated only when the TWW was diluted. Untreated straw yielded 255 NL CH₄ (kg VS) ^-1, whereas straw that had been pre-treated with TWW yielded 314 NL CH₄ (kg VS)^-1 (35% increase). Treatment of TWW by AD with a co-substrate might be possible using a controlled feedstock mixing ratio. Use of TWW as a pre-treatment medium by simple co-storage before AD would be beneficial as an inexpensive treatment of lignocellulosic biomass.