Enhanced mesophilic anaerobic digestion of food waste by thermal pretreatment: Substrate versus digestate heating

•Thermal pretreatment could enhance biomethanation by more than 40%.•The main effect of the pretreatments was increased solubilization of COD.•Conventional thermal pretreatment at 80°C for 1.5h resulted in the highest BMP.•Similar enhancement was obtained with thermophilic pretreatment at 50°C for 6...

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Bibliographic Details
Published in:Waste management (Elmsford) 2015-12, Vol.46, p.176-181
Main Authors: Ariunbaatar, Javkhlan, Panico, Antonio, Yeh, Daniel H., Pirozzi, Francesco, Lens, Piet N.L., Esposito, Giovanni
Format: Article
Language:English
Subjects:
Anaerobic digestion
Anaerobiosis
Biogas
Bioreactors
Chemical oxygen demand
Conventional thermal pretreatment
Energy requirement
Food waste
Foods
Garbage
Heating
Hot Temperature
Methane - analysis
Oxygen demand
Pretreatment
Renewable Energy
Thermophilic pretreatment
Wastes
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Summary:•Thermal pretreatment could enhance biomethanation by more than 40%.•The main effect of the pretreatments was increased solubilization of COD.•Conventional thermal pretreatment at 80°C for 1.5h resulted in the highest BMP.•Similar enhancement was obtained with thermophilic pretreatment at 50°C for 6–12h.•Thermal pretreatment is more energy efficient than thermophilic pretreatment. Food waste (FW) represents a source of high potential renewable energy if properly treated with anaerobic digestion (AD). Pretreating the substrates could yield a higher biomethane production in a shorter time. In this study, the effects of thermal (heating the FW in a separate chamber) and thermophilic (heating the full reactor content containing both FW and inoculum) pretreatments at 50, 60, 70 and 80°C prior to mesophilic AD were studied through a series of batch experiments. Pretreatments at a lower temperature (50°C) and a shorter time (55°C) and longer operating times (>12h) yielded higher soluble chemical oxygen demand (CODs), but had a negative effect on the methanogenic activity. The thermal pretreatments at the same conditions resulted in a lower solubilization of COD. Based on net energy calculations, the enhanced biomethane production is sufficient to heat up the FW for the thermal, but not for the thermophilic pretreatment.
ISSN:0956-053X
1879-2456
DOI:10.1016/j.wasman.2015.07.045