Semi-continuous anaerobic digestion of food waste using a hybrid anaerobic solid-liquid bioreactor

Abstract

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.

Comparison of lab-scale and pilot-scale hybrid anaerobic solid–liquid systems operated in batch and semi-continuous modes

“…3b). Biogas production rates were from 42 l day À1 to 150 l day À1 during the start-up (day 0-4) and from 116 l day À1 to 168 l day À1 during semi-continuous operation (day [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. The methane content in biogas was in the range from 60% to 78% with an average value of 74%.…”

“…The hybrid anaerobic solid-liquid (HASL) system was developed to improve food waste bioconversion in conventional two-phase anaerobic digester [15,20,21]. The HASL system includes an acidogenic reactor (Ra) to treat solid food waste and an upflow anaerobic sludge blanket (UASB) methanogenic reactor (Rm) to treat liquid leachate from acidogenic reactor (Fig.…”

Anaerobic Digestion of Dairy Manure in a Hybrid Reactor with Biogas Recirculation

“…This is clear from the fact that they have been successively used for digestion of food wastes containing high solids concentrations (Hai-Lou et al 2002;Wang et al 2002Wang et al , 2003 as well as that of swine (Lo et al 1994) and dairy (Co´rdoba et al 1995) operations. Even though it represents a viable option, hybrid process configurations for anaerobic digestion of manure have been the subject of a very limited number of investigations on poultry and swine manure (Yang et al 1989(Yang et al , 1993 and none on dairy manure.…”

Performance assessment of two-stage anaerobic digestion of kitchen wastes

“…[10][11][12] Due to the high moisture and high organic matter content of kitchen wastes, two-stage wet anaerobic digestion has usually been employed in methane recovery from kitchen wastes. Cho and Park [13] applied the two-stage anaerobic digestion process to experiments on Korean food wastes, Bouallagui et al [14] on fruit and vegetable wastes and Wang et al [15,16] developed a hybrid bioreactor for food wastes. Most of these studies focused on the evaluation of the ultimate bioenergy production potential.…”