Semi-continuous anaerobic digestion of food waste using a hybrid anaerobic solid-liquid bioreactor.
A hybrid anaerobic solid-liquid (HASL) bioreactor was developed to enhance food waste conversion. The HASL bioreactor is a modified two-phase anaerobic digestion system with a solid waste reactor and a high-rate anaerobic wastewater reactor, which was a UASB reactor. In this study, the methanogenesis in the UASB reactor was investigated under a semi-continuous operation of the food waste digestion system. The HASL process, including 7 days of start-up and 23 days of semi-continuous operation followed by 6 days of batch operation, was commenced by loading 2.8 kg of shredded food waste. During the semi-continuous operation, 0.2 kg of the same waste was loaded daily. The leachate from acidification phase, i.e., solid waste reactor, remained acidic (pH 4.9-5.5) and high in total VFA (TVFA), 9,500-11,500 mg/L, and COD (8,000-11,800 mg/L) levels. In the methanogenesis phase, i.e., UASB reactor, effective TVFA and COD removals (88 +/- 5% and 85 +/- 7%, respectively) were obtained, while the methane content was 71%. At the end of operation, about 78% of VS added in the HASL bioreactor was removed, while TOC and total COD reductions were 78% and 79%, respectively. The results showed that the use of UASB reactor in the semi-continuous HASL system can enhance the methanogenesis process and increase the methane content in biogas production.
Wang
J Y
JY
Environmental Engineering Research Centre, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.
Xu
H L
HL
Zhang
H
H
Tay
J H
JH
D001421:Bacteria, Anaerobic / Q000502:physiology*; D019149:Bioreactors; D019649:Food Industry; D008697:Methane / Q000032:analysis; D012037:Refuse Disposal / Q000379:methods*
D008697:Methane