碩士 / 逢甲大學 / 綠色能源科技碩士學位學程 / 99 / The cheap substrate can improve competitiveness for dark
fermentative hydrogen production. In order to develop the pilot
technology of hydrogen production from non-grain feedstock, this study
explored the hydrogen production from desizing wastewater (DW) and
condensed molasses fermentation soluble (CMS) using 60 and 400 L
pilot-scale fermentors, respectively. It is expected that experiment results
obtain several related parameters for scale up and futher connect with
commercial processes. In addition, the microbial community structure in
systems was analysed by using molecular biological techniques.
DW was initially conducted the experiments of environmental
factors and operation strategies with a lab-scale continuous flow stirred
tank reactor (CSTR). The results showed that combination substrate
preheating (60℃, 1 h) and HRT (hydraulic retention time) 12 h could
inhibit the activity of non-hydrogen-producing bacteria and improve the
stability of system operation. The optimum pH value was 5.5, but the
CSTR reactor could not be operated steady at a HRT of 8 h. DW via
saccharification pretreatment could improve this problem, obtaining a H2
production rate (HPR), H2 yield (HY) and overall H2 production
efficiency (HPE) of 15.2 m3/m3/d, 9.77 mmol-H2/g-hexose and 37.5%,
respectively, at a HRT of 8 h. If the pretreatment processes combined
saccharification with alkali (pH 10.0-10.5) treatment, it could further
improve the hydrogen yield.
Unfortunately, the 60 L pilot-scalr reactor could not be started up by
feedimg variously pretreated DW. However, the waste concentrated
beverage added 0-10% (total sugar ratio) DW could be successfully
operated at HRT 6 h, getting a HPR, HY and HPE of 20.2 m3/m3/d, 8.7
mmol-H2/g-hexose and 37.2%, respectively. The analytical results of
microbial community structure showed that hydrogen-producing
Clostridium sp. existed in the reactor for three stages of addition of
0-10% DW, and C. butyricum was the predominant H2-producing
bactrrim in the system. However, hydrogen production decreased to near
zero when the addition of DW was increased to 20%. The analytical
results of microbial community structure showed that C. butyricum still
presented in the reactor. Accordingly, the main cause of stopping
hydrogen production should not result from propagation of non-H2-
producing bacteria in the fermentor. It is highly probable that chemical
substances of hydrogen inhibition existed in desizing water.
The 400 L pilot–scale bioreactor could successfully start up by
feeding CMS at HRT 6 h (Cs = 40 g COD/L). However, the performance
of hydrogen production became periodic fluctuation situation. This
problem could be improved by substrate preheating (60℃, 1 h), obtaining
a HPR and HY of 17.8 m3/m3/d and 9.1 mol H2/g-hexose, respectively, at .
HRT 4 h and substrate concentration 70 g COD/L (total sugar
concentration 17.7 g/L). The analytical results of microbial community
structure showed that Corynebacterium glutamicum presented in the
system became non-predominant bacterium by substrate preheating,
resulting in the shift from lactate fermentation into butyrate fermentation.
In addition, the Megasphaera sp., which can decompose carbohydrates
and lactate to produce hydrogen, was found that existed in the system of
substrate preheating. According to the desrese of lactate content in
soluble metabolites, there was speculatation that Megasphaera sp. gave
some contribution to hydrogen production.
| Identifer | oai:union.ndltd.org:TW/099FCU05160005 |
| Date | January 2011 |
| Creators | Yu-hsiang Hsieh, 謝裕翔 |
| Contributors | Ping-jie Lin, 林屏杰 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 180 |
Page generated in 0.0151 seconds