Thermophilic adaptation of a mesophilic anaerobic sludge for food waste treatment

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Journal titleJournal of Environmental Management
Pages517525; # of pages: 9
SubjectAnaerobiosis; anaerobic digestion; animals; bacteria, anaerobic; biomass; bioreactors; biogas production; fermentation; food waste; garbage; heat; malus; milk; refuse disposal; waste products; anaerobic digestion; mesophilic conditions; thermophilic adaptation
AbstractAs opposed to mesophilic, thermophilic anaerobic digestion of food waste can increase the biogas output of reactors. To facilitate the transition of anaerobic digesters, this paper investigated the impact of adapting mesophilic sludge to thermophilic conditions. A 5L bench scale reactor was seeded with mesophilic granular sludge obtained from an up-flow anaerobic sludge blanket digester. After 13 days of operation at 35 degrees C, the reactor temperature was instantaneously increased to 55 degrees C and operated at this temperature until day 21. The biomass was then fed food waste on days 21, 42 and 63, each time with an F/M (Food/Microorganism) ratio increasing from 0.12 to 4.43 gVS/gVSS. Sludge samples were collected on days 0, 21, 42 and 63 to conduct substrate activity tests, and reactor biogas production was monitored during the full experimental period. The sludge collected on day 21 demonstrated that the abrupt temperature change had no pasteurization effect, but rather lead to a biomass with a fermentative activity of 3.58 g Glucose/gVSS/d and a methanogenic activity of 0.47 and 0.26 g Substrate/gVSS/d, related respectively, to acetoclastic and hydrogenophilic microorganisms. At 55 degrees C, an ultimate gas production (Go) and a biodegradation potential (Bo) of 0.2-1.4 L(STP)/gVS(fed) and of 0.1-0.84 L(STP) CH(4)/gVS(fed) were obtained, respectively. For the treatment of food waste, a fully adapted inoculum was developed by eliminating the initial time-consuming acclimatization stage from mesophilic to thermophilic conditions. The feeding stage was initiated within 20 days, but to increase the population of thermophilic methanogenic microorganisms, a substrate supply program must be carefully observed.
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AffiliationNational Research Council Canada; NRC Biotechnology Research Institute
Peer reviewedNo
NRC number49030
NPARC number12332901
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Record identifier12c45449-ed48-4c45-a67a-ac739744672c
Record created2009-09-10
Record modified2016-05-09
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