Abstract: Hydrogen can be obtained by anaerobic fermentation of sewage sludge.
Therefore, in this paper the effects of thermally pretreated temperatures on
hydrogen production from sewage sludge were investigated under different
pre-treatment conditions. In the thermal pretreatment, some microbial matters
of sludge were converted into soluble matters from insoluble ones. As a result,
the suspended solid(SS) and volatile suspended solid(VSS) of sludge decreased
and the concentration of soluble COD(SCOD) increased, including soluble
carbohydrates and proteins. The experimental results showed that all of those
pretreated sludge could produce hydrogen by anaerobic fermentation and the
hydrogen yields under the temperatures of 121°C; and
50°C were 12.23 ml/g VS(most) and 1.17 ml/g VS (least),
respectively. It illuminated that the hydrogen yield of sludge was affected by
the thermally pretreated temperatures. Additionally, the endurance of high
hydrogen yield depended on the translation of microbial matters and inhibition
of methanogens in the sludge. The temperatures of 100°C and
121°C (treated time, 30 min) could kill or inhibit completely the
methanogens while the others could not. To produce hydrogen and save energy,
100°C was chosen as the optimal temperature for thermal
pretreatment. The composition changes in liquid phase in the fermentation
process were also discussed. The SCOD of sludge increased, which was affected
by the pretreatment temperature. The production of volatile fatty acids in the
anaerobic fermentation increased with the pretreatment temperature.
Keywords: anaerobic fermentation, hydrogen production, sewage sludge, thermally pretreated temperature