title: Optimization of micro-aeration intensity in acidogenic reactor of a two-phase anaerobic digester treating food waste.
abstract: Micro-aeration is known to promote the activities of hydrolytic exo-enzymes and used as a strategy to improve the hydrolysis of particulate substrate. The effect of different micro-aeration rates, 0, 129, 258, and 387 L-air/kg TS/d (denoted as LBR-AN, LBR-6h, LBR-3h and LBR-2h, respectively) on the solubilization of food waste was evaluated at 35°C in four leach bed reactors (LBR) coupled with methanogenic upflow anaerobic sludge blanket (UASB) reactor. Results indicate that the intensity of micro-aeration influenced the hydrolysis and methane yield. Adequate micro-aeration intensity in LBR-3h and LBR-2h significantly enhanced the carbohydrate and protein hydrolysis by 21-27% and 38-64% respectively. Due to the accelerated acidogenesis, more than 3-fold of acetic acid and butyric acid were produced in LBR-3h as compared to the anaerobic treatment LBR-AN resulting in the maximum methane yield of 0.27 L CH4/g VS(added) in the UASB. The performance of LBR-6h with inadequate aeration was similar to that of LBR-AN with a comparable hydrolysis degree. Nevertheless, higher aeration intensity in LBR-2h was also unfavorable for methane yield due to significant biomass generation and CO2 respiration of up to 18.5% and 32.8% of the total soluble hydrolysate, respectively. To conclude, appropriate micro-aeration rate can promote the hydrolysis of solid organic waste and methane yield without undesirable carbon loss and an aeration intensity of 258 L-air/kg TS/d is recommended for acidogenic LBR treating food waste.
authors.affiliation: Department of Environmental & Low-Carbon Science, School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai, China; Sino-Forest Applied Research Centre for Pearl River Delta Environment, Department of Biology, Hong Kong Baptist University, Hong Kong Special Administrative Region.
authors.forename: Suyun
authors.initials: S
authors.lastname: Xu
authors.affiliation: Sino-Forest Applied Research Centre for Pearl River Delta Environment, Department of Biology, Hong Kong Baptist University, Hong Kong Special Administrative Region.
authors.forename: Ammaiyappan
authors.initials: A
authors.lastname: Selvam
authors.affiliation: Sino-Forest Applied Research Centre for Pearl River Delta Environment, Department of Biology, Hong Kong Baptist University, Hong Kong Special Administrative Region. Electronic address: jwcwong@hkbu.edu.hk.
authors.forename: Jonathan W C
authors.initials: JW
authors.lastname: Wong
mesh_terms: D000388:Air; D000693:Anaerobiosis; D056804:Biofuels / Q000706:statistics & numerical data; D019149:Bioreactors; D005502:Food; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008697:Methane / Q000096:biosynthesis*; D012037:Refuse Disposal / Q000295:instrumentation / Q000379:methods*; D064091:Waste Disposal Facilities / Q000295:instrumentation*; D014874:Water Pollutants, Chemical / Q000378:metabolism
chemical_list: D056804:Biofuels; D014874:Water Pollutants, Chemical; D008697:Methane
keywords: Acetic acid; Butyric acid; Methane production; Micro-aeration; Protein hydrolysis