| Summary: | The aim of this research was to study the influence of various variables on
anaerobic co-digestion process of tofu waste water and cow manure, i.e. the
influence of the addition of active digested sludge as a starter, the influence of O2
removal at the initial process, the influence of the amount of tofu waste water, cow
manure, and active digested sludge, and the influence of the feeding strategies of tofu
waste water on biogas production and methane yield.
Batch and fed batch experiment was done in a closed digester. Batch
experiment was started with putting the tofu waste water, cow manure, and active
digested sludge with a certain ratio to the digester, and mix its until homogen.
Nitrogen gas was flushed into digester, the digester was closed, and the process was
run. Fed batch experiment was started with putting cow manure and active digested
sludge to the digester, and after process occur, tofu waste water fed in to the digester
periodically. In both experiment the formed gas volume was noted every day and at
certain times gas and slurry was taken from the digester for analysis purposes.
The result of this research showed that the addition of active digested sludge
as a starter could cause a formation of methane on biogas production from tofu
waste water. The addition of digested sludge of 1/3 total material weight would
shorten more than 50% production time. The presence of little O2 at the initial
process had no significant effect on gas production and methane yield. The good
weight ratio of tofu waste water, cow manure, and active digested sludge was 3 : 1 :
2. In the right composition, mixing tofu waste water as a co-substrate with cow
manure would increase biogas production from cow manure, and feeding tofu
wastewater frequently would reduce methane production.
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