Biomethanation Potential and Enhancement of Acacia Leaves Waste via Pretreatment and Co-Digestion Strategy

Abstract

Acacia leaves waste biomass (AcLW) is an attractive feedstock for biomethane production by its generation amounts practically. This study evaluated the methane productivity of AcLW and its enhancement via alkaline pretreatment and co-digestion strategy. The effect of pretreatment conditions and process configuration on methane yields were investigated. The results showed that raw AcLW digestion in the single-stage process generated about 41.32 m3-CH4/kg VSadded, which increased significantly by 1.94-2.51 times to be 80.05-103.85 m3-CH4/kg VSadded for alkaline and 93.31-182.26 m3-CH4/kg VSadded for alkali-thermal pre-treated samples. The increase of NaOH concentration, soaking time and thermal supplementation affected methane productivity directly, while co-digestion with pulp bio-sludge at identical solid conditions promoted about 3.38 times or 162.7 m3-CH4/kg VSadded compared to raw AcLW digestion. A profitable operation of two separated stages combining leaching bed acidification and CSTR was also depicted with 152.1 m3-CH4/kg VSadded.The maximum gases productivity of AcLW digestion was promoted with alkaline-thermal pre-treated biomass for 3.60-4.41 times increase with 67.02-75.59% of total solids reduction. This finding demonstrated the biomethanation potential of AcLW and its enhancement after pretreatment and co-digestion significantly, which increased its possibility as a biogas feedstock.

Keywords

• pretreatment
• paper waste
• leaves biomass
• methane yield
• alkaline thermal treatment