Effect of liquid hot water pre-treatment on sugarcane press mud methane yield

• Improved biomethanation by LHW pre-treatment compared with untreated press mud.
• A 33% COD solubilisation resulted in the best methane yield (>55% increase).
• Increase of methane yield by a maximum of 63% at 150 °C for 20 min.
• Highest furfural concentration of 1214.17 mg L−1 was found at 200 °C for 5 min.
• HAc release was influenced more by temperature than by pre-treatment severity.

Sugarcane press mud was pretreated by liquid hot water (LHW) at different temperatures (140–210 °C) and pre-treatment times (5–20 min) in order to assess the effects on the chemical oxygen demand (COD) solubilisation, inhibitors formation and methane yield. The experimental results showed that a high degree of biomass solubilisation was possible using LHW. Higher methane yields were obtained at lower severities (log(Ro) = 2.17–2.77) with (i) mild temperatures (140–150 °C) and long contact times (12.5 min, 20 min) or (ii) mild temperatures (175 °C) with short contact time (2 min). The highest increase in methane yield (up to 63%) compared to the untreated press mud was found at 150 °C for 20 min. At temperatures of 200 °C and 210 °C, low methane efficiency was attributed to the possible formation of refractory compounds through the Maillard reaction.