Effect of ultrasonic pretreatment on methane production from peat

Abstract

This study investigated the effects of ultrasonic pretreatment on the chemical composition and biomethane production of herbaceous, woody, and mossy peats. The optimal conditions for ultrasonic pretreatment were established through single-factor and orthogonal experiments, utilizing reducing sugar yield as a key metric. Daily gas production, volatile fatty acids concentrations, pH levels, and reducing sugar yields during methane fermentation were measured to assess the effects of ultrasonic pretreatment on peat biomethanation. The optimal pretreatment conditions for mossy, herbaceous plants, and woody peat are 25 min, 35 min, and 2 min of ultrasonic treatment at 50 °C, 70 °C, and 60 °C, respectively. The solid-liquid ratios are 1:5, 1:3, and 1:3, respectively, and the particle sizes are 250 mesh, 250 mesh, and 40 mesh, respectively. After ultrasonic treatment, the contents of hemicellulose, and lignin decreased by 2.32 %, 1.77 %, respectively, in mossy peat; 1.00 %, and 2.70 %, respectively, in herbaceous peat; and 0.76 %, and 2.28 %, respectively, in woody peat. After ultrasonic treatment, the total biomethane production from mossy, herbaceous, and woody peats increased by 119.05 %, 84.69 %, and 13.55 %, respectively. Ultrasonic pretreatment enhances peat's biodegradability and biomethane production, thus being an effective strategy for increasing peat's biomethane yield.