Biogas production comparison of liquid anaerobic digestion (L-AD) methods on different enzyme addition

Abstract

Biogas, the gas generated from organic fermentation under anaerobic conditions, is an alternative way to combat the energy crisis. Rice husk is a biomass fuel, and as an agricultural country, Indonesia has not utilized this excessive waste opportunity. Bacteria break down organic matter without oxygen, called the Liquid Anaerobic Digestion (L-AD) method with the minimum condition of 10% total solids (TS) and 25% C/N ratio. Lignin content in rice husk could inhibit the degradation processes, hence pretreatment is a prerequisite. This study was designed to determine the optimum pretreatment concentration variation of amylase and cellulase enzyme (9%, 12%, 15%, 18%) in a persistent chemical condition (NaOH 6%). Within 40 days of observation, both biological pretreatments increased biogas yield contrary. The result showed that the pretreatment of a lower concentration of amylase enzyme (9%) produces a significant biogas yield of about 981 ml or 45.82 ml/grTS. On the other way, higher cellulase enzyme concentration (18%) produced 1520 ml or 70.99 ml/TS. The rate of biogas production were (U) 1.27 (ml/gr/TS.day) for amylase and 4.60 (ml/gr/TS.day) for cellulose.