Pre-treatments for enhanced biochemical methane potential of bamboo waste

• Bamboo waste is a potential feedstock for methane production.
• Methane yields from bamboo waste increased with decreasing particle sizes.
• Pre-treatments led improvements in both sugars and methane yields.
• Mild alkaline pre-treatment was most efficient in enhancing methane yields.
• Competition for biomass for food/feed is avoided by converting bamboo to methane.

Various pre-treatments (acid, alkaline, enzyme and alkaline aided enzyme also termed combined) were evaluated on different fractions of bamboo waste from a chopstick production factory. Chemical oxygen demand (COD) solubilisation, monomeric/dimeric sugar yield, methane yield enhancement and methane production rate were assessed. The biochemical methane potential was determined in batch assays under mesophilic conditions (37 ± 1 °C) using the Automatic Methane Potential Test System (AMPTS-II).Pre-treatments led to enhanced COD solubilisation as compared to raw sample. Alkaline aided enzymatic pre-treatment led to the highest sugar yield, comparable to the theoretical yield. However, high sugar yield did not translate to high methane yield. The best pre-treatment in terms of methane yield was alkaline pre-treatment which resulted in a surplus of up to 88% methane yield. There was a positive correlation between dissolved COD and methane yield. Methane yield and methane production rate also increased with decreasing particle sizes. In all investigated scenarios, pre-treatment led to an improved methane production rate as compared to the raw samples.These results demonstrated that alkaline pre-treatment at ambient temperature was an efficient treatment option to improve methane yield of bamboo waste.