Yue-Qin et al (2008) [43] produced ethanol from
kitchen waste in this study. The process consists of
freshness preservation of the waste,
saccharification of the sugars in the waste,
continuous ethanol fermentation of the
saccharified liquid and anaerobic treatment of the
saccharification residue and the stillage. Spraying
lactic acid bacteria (LCB) on the kitchen waste kept
the waste fresh for over 1 week. High glucose
recovery (85.5%) from LCB-sprayed waste was
achieved after saccharification using Nagase N-40
glucoamylase. The resulting saccharified liquid was
used directly for ethanol fermentation, without
the addition of any nutrients. High ethanol
productivity (24.0 g l-1 h-1) was obtained when
the flocculating yeast strain KF-7 was used in a
continuous ethanol fermentation process at a
dilution rate of 0.8h-1. The saccharification residue
was mixed with stillage and treated in a
thermophilic anaerobic continuous stirred tank
reactor (CSTR); a VTS loading rate of 6 g l-1 d-1
with 72% VTS digestion efficiency was achieved.
Using this process, 30.9 g ethanol, and 65.2 l
biogas with 50% methane, was produced from 1
kg of kitchen waste containing 118.0 g total sugar.
Thus, energy in kitchen waste can be converted to
ethanol and methane, which can then be used as
fuels, while simultaneously treating kitchen waste.