Influence of Subcritical Water Pretreatment Temperature on Pineapple Waste Biogas Efficiency: Experimental and Kinetic Study

Abstract

Anaerobic digestion of pineapple waste appears to be an effective method for non-renewable energy substitution through biogas production. The potential power generation from the exploitation of pineapple waste as fuel is estimated to be roughly 20.8 MW. Nevertheless, the intricate composition of pineapple waste, characterized by the complex arrangement of its structure, poses a significant challenge in attaining a substantial amount of biogas production. This study pretreated pineapple waste with subcritical water to increase biogas production. Two temperature settings (120⁰C and 200⁰C) were used for pretreatment. Combined pre-treatment at low temperatures and short time (120⁰C, 5 minutes, 10 water to solid ratio) resulted in 31.6% higher biogas production than untreated. However, pretreatment at high temperatures and longer reaction time (200⁰C,25 min) reduced the biogas production by 9% as compared to untreated. Using the Modified Gompertz kinetic model, pretreatment improved the lag phase and increased biogas production to 14.41 mL/day. The lignocellulosic composition of pre-treated pineapple waste decreased, while process parameters such as total ammonia nitrogen removal and pH improved after the pretreatment. Subcritical water pretreatment, particularly when conducted at high temperatures, did not yield any enhancements in the anaerobic digestion of pineapple waste. As a result, it is not advisable to employ this method for these purposes.

Optimization of Subcritical Water Pretreatment on Glutinous Rice Husk for Efficient Sugar and Hydrogen Production

“…5 (e) and (f) suggested less time-consuming effects and that mild temperatures were better for biogas yield. This result is consistent with findings by Adila et al [53], where a combined pretreatment of pineapple waste by SCW, at low temperatures and short duration (120°C for 5 minutes with a 10:1 water-to-solid ratio) led to a 31.6% increase in biogas production compared to untreated samples. Conversely, pretreatment at higher temperatures and extended reaction times (200°C for 25 minutes) resulted in a 9% decrease in biogas production relative to untreated samples.…”

“…The GRH surface was substantially altered by SCW pretreatment. The SCW pretreatment condition under high temperature at a sub-critical level caused the disorderliness of hemicellulose and the degradation of the cellulose and lignin structures [53]. The lignocellulosic structure of the GRH experienced increased surface opening following pretreatment, as shown in Fig.…”