Enhancement of Biogas Production Potential from Water Hyacinth by Thermal and Waved Pre-Treatment

Abstract

This research aims to study methods for water hyacinth pre-treatment by thermal and waved applications in order to use as a feedstock for anaerobic digestion in attempt to promote biogas production potential and enhancing substrate readily. The thermal pre-treatment techniques applied in this study are hot air oven, temperature controlled water bath, and steam pressure autoclave, while ultrasonic waves are performed at different temperatures and durations. The water hyacinth pre-treatment efficiency was determined by the transformation of organic compounds into soluble form, including CODs and VFAs. It was found that CODs tended to increase with higher temperature and duration of heating and waving. Microwave heating at 220 °C for 10 min yielded the highest CODs at 3,498 mg/L, while the highest CODs increase compared to the absence of conditioning was 17.8 folds at 160 °C for 10 min. Ultrasonic irradiation had the lowest rate of CODs increment of 1.0 - 2.3 folds, and maximum CODs of 533 mg/L was found when ultrasonic was applied for 20 min at room temperature. Direct heating by hot water bath showed maximum CODs of 2,467 mg/L (100 °C 120 min). Hot air oven had a maximum CODs of 2,250 mg/L (110 °C 120 min), whereas an autoclave presented maximum CODs of 924 mg/L (105 °C 20 min). These indicated that the pre-treatment methods of water hyacinth by heating and waving resulted in an increase in organic matter in soluble form which is readily available as a substrate for anaerobic digestion. Therefore, more biodegradable substrate and biogas production potential enhancement could be expected.